Obtaining Zeolites from Natural Materials of Volcanic Origin for Application...

[Full title: Obtaining Zeolites from Natural Materials of Volcanic Origin for Application in Catalytic Pyrolysis for the Sustainable Chemical Recycling of Polymers]

[Find the meaning and references behind the names: De La Cruz, Luis Fernando, Angel Gabriel, La Cruz, Natural, Nacional, Doi, June, Jonathan, Basel, San, Peru, Silva, Almir, Churata, Gas, Yuan, Angel, Fernando, Zone, Ring, Santa, Madrid, Low, Luis, Present, Ning, Huaman, Francisco, Show, Central, Edu, Large, Henry, Part, Gabriel, Ability, Cercado, Under, Iii, Ing, Catalina, Mamani, Proton, Pacific, Cruz, Cooling, Cost, July, Open, Quispe, Andes, Arequipa, Chemical, Spain, Carlos, Fuentes, Jose, Southern, Rate, Alejandro, Velasco, Calle, Sandro, Light, Bet, Study, Strong, Min, Tel, Sem, Vela, Flow, Valencia]

Citation: Valencia-Huaman, A.G.; Fuentes-Mamani, S.H.; Mamani-De La Cruz, L.F.; Velasco, F.; Churata, R.; Silva-Vela, A.; Mamani-Quispe, J.; Almir ó n, J. Obtaining Zeolites from Natural Materials of Volcanic Origin for Application in Catalytic Pyrolysis for the Sustainable Chemical Recycling of Polymers Sustainability 2024 , 16 , 5910. https://doi.org/ 10.3390/su 16145910 Academic Editor: Ning Yuan Received: 7 May 2024 Revised: 23 June 2024 Accepted: 2 July 2024 Published: 11 July 2024 Copyright: © 2024 by the authors Licensee MDPI, Basel, Switzerland This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/) sustainability Article Obtaining Zeolites from Natural Materials of Volcanic Origin for Application in Catalytic Pyrolysis for the Sustainable Chemical Recycling of Polymers Angel Gabriel Valencia-Huaman 1 , Sandro Henry Fuentes-Mamani 1 , Luis Fernando Mamani-De La Cruz 1 , Francisco Velasco 2 , Rossibel Churata 3 , Alejandro Silva-Vela 3 , Jose Mamani-Quispe 1 and Jonathan Almir ó n 1, * 1 Escuela Profesional de Ingenier í a Ambiental, Facultad de Ingenier í a de Procesos, Universidad Nacional de San Agust í n de Arequipa, Calle Santa Catalina Nro. 117 Cercado, Arequipa 04001, Peru; avalenciah@unsa.edu.pe (A.G.V.-H.); sfuentesm@unsa.edu.pe (S.H.F.-M.); lmamanidel@unsa.edu.pe (L.F.M.-D.L.C.); josmamaniqui@unsa.edu.pe (J.M.-Q.) 2 Materials Science and Engineering Department, IAAB, Universidad Carlos III de Madrid, 28005 Madrid, Spain; fvelasco@ing.uc 3 m.es 3 Escuela Profesional de Ingenier í a de Materiales, Facultad de Ingenier í a de Procesos, Universidad Nacional de San Agust í n de Arequipa, Calle Santa Catalina Nro. 117 Cercado, Arequipa 04001, Peru; rchurataa@unsa.edu.pe (R.C.); asilva@unsa.edu.pe (A.S.-V.) * Correspondence: jalmiron@unsa.edu.pe; Tel.: +51-95-0000426 Abstract: The present investigation studies the use of three natural precursors of volcanic origin (pozzolana, ignimbrite and pumice) in the synthesis of low-cost and environmentally friendly zeolites. The developed zeolites were evaluated as sustainable catalysts for the catalytic pyrolysis process in the chemical recycling of polypropylene. A zeolite was synthesized from each precursor. The hydrothermal treatment was performed with NaOH (3 M) at 160 ◦ C for 72 h and NH 4 Cl (1 M) was added to convert it into proton form. The synthesized zeolites were characterized by FTIR, XRD, SEM and BET. The evaluation of the catalytic ability of the obtained zeolites was carried out with polypropylene mixed with a 4, 6 and 8 wt.% catalyst in a ceramic crucible. Pyrolysis was always carried out at 450 ◦ C and for 30 min in a tubular furnace with a continuous flow rate of 250 L · min − 1 of gaseous nitrogen. The gases generated were captured in the cooling system. The characterized zeolites show a resemblance to the ZSM-5 commercial zeolite, especially for the ignimbrite and pozzolan zeolites. Likewise, in pyrolysis, liquid products, gases and waxes were obtained. As the amount of catalyst was increased (from 4 to 8%), the yield of the desired liquid–gas products was also increased. The synthesized zeolites showed similar pyrolytic characteristics to ZSM-5, although they did not reach the same pyrolytic efficiency. Zeolites improved the pyrolysis products, especially at 8 wt.%, when compared to thermal pyrolysis. This study highlights the potential of the developed zeolite catalysts to efficiently convert PP into valuable light olefins, advancing sustainable polyolefin recycling technologies Keywords: zeolite; synthesis; pyrolysis; polypropylene; ZSM-5; volcanic materials; catalytic efficiency; chemical recycling 1. Introduction Southern Peru is located in the central volcanic zone of the Andes, part of the Pacific Ring of Fire. This region has witnessed a large number of volcanic phenomena, with large emissions of volcanic material throughout history [ 1 ]. Depending on the specific formation and cooling conditions during volcanic activity, different volcanic materials can form (ignimbrite, pumice, pozzolana, obsidian, etc.). These materials present optimal properties in terms of their chemical stability, thermal stability, hardness, etc., and, thanks Sustainability 2024 , 16 , 5910. https://doi.org/10.3390/su 16145910 https://www.mdpi.com/journal/sustainability

[Find the meaning and references behind the names: Williams, New, Act, Better, Seed, Zang, Stone, Commerce, Active, Fields, Time, Carbon, Paula, Main, Exceptional, Size, Zaarour, Hand, High, Mass, Fau, Acid, Nap, Energy, Bags, Market, Evolution, Due, Alkali, Lower, Pore, Target, Santoso, Good, Common]

Sustainability 2024 , 16 , 5910 2 of 15 to their high Si and Al proportions [ 2 ], they show characteristics that make them valid as precursors for the formation of geopolymers [ 3 ] or synthetic zeolites [ 4 , 5 ]. Synthetic zeolites are solid minerals composed of Si, Al and O in high proportions, with well-organized three-dimensional structures. They act as a selective molecular sieve [ 6 , 7 ] in terms of the type, size and polarity of the molecule [ 8 ], taking advantage of the acid sites This enhances their applicability to different needs in industry and science. Moreover, the synthesis conditions (concentration, temperature and time) [ 9 ] can be easily controlled. The current specialized routes (seed-assisted synthesis, microwave, sonic, etc.) are efficient for the synthesis of zeolites, such as the synthesis of Soconi Mobile Zeolite (ZSM) [ 10 – 12 ], which is widely used at an industrial scale. However, ZSM synthesis requires immense logistics and a considerable energy demand, and presents difficulties in terms of its scalability to the industry. In contrast, the conventional route used in this research has a low cost, takes advantage of the abundance and properties of sustainable natural precursors, can be easily replicated and can be assisted through the use of an organic template as a directing agent to control the formation of the desired structure. Nevertheless, all of these methods involve hydrothermal conditions, that promote nucleation processes, changes in intermediate phases and selective crystallization [ 8 ]. In 2022, the zeolite market reached a production of 2.1 Mt, projecting an evolution rate of 2.3% by 2028. Expected market demand will be satisfied with new industrial methodologies [ 6 ] since the flexibility of their application covers many fields of study The research of Zaarour et al. found photovoltaic and antimicrobial applications that could increase the efficiency of zeolites after doping with cation Ag [ 9 ]. Williams et al gathered information on the potential applications of zeolites [ 13 ]. One of their very common applications is in environmental treatment, taking advantage of the size of the pore for the absorption of metals such as Pb +2 , in which good results were obtained with the NaP 1 zeolite and Sodalite [ 14 ]; on the other hand, the use of pumice stone as a precursor served to synthesize NaP 1 zeolite and Phyllipsite, which also obtained optimal results for environmental remediation [ 4 , 13 , 15 ] and improvements in agricultural soil as a water retainer [ 16 ]. In addition to the aforementioned studies, zeolites are often used as heterogeneous catalysts by the catalytic cracking industry due to their potential ability to chemically recycle petroleum-based polymers into functional monomers (depolymerization) [ 17 – 19 ]. Different catalysts in catalytic pyrolysis and the gasification of waste plastics are used to improve product selectivity. The selection of the appropriate catalyst for the decomposition of waste plastics can improve the conversion rate and promote high yields of gaseous products and syngas [ 20 ]. The catalytic effect of ZSM-5 (MFI type; 10-membered rings; constructed from a pentasyl unit) and zeolite-y (FAU type; 12-membered rings; constructed from a sodalite unit) catalysts has been extensively studied. It has been identified that structural changes in zeolite catalysts can increase the yield of valuable products, isomerize the main carbon structure and decompose heavy compounds and convert them into aromatics [ 21 ]. Research conducted on catalytic cracking by Zang et al., with low-density polyethylene (LDPE) and the synthesized zeolite ZSM-5, evidenced a better performance for oils and a clear pyrolysis temperature decrease of more than 50 ◦ C [ 22 ]. Furthermore, the acid-active sites generate compounds of a lower molecular mass [ 23 ]. There is also polypropylene (PP), a similar polymer with exceptional chemical resistance and the ability to withstand high temperatures, which is widely used in domestic and industrial activities (containers, plastic bags, packaging, pieces of machinery, etc.). Together with PE, up to 2021, plastic producing industries represented 76% of plastic production in Peru, with the construction, commerce, beverage and chemical products manufacturing industries serving as the target markets [ 24 ]. Santoso et al. activated a natural zeolite, abundant in the mordenite phase, for the pyrolysis of PP and LDPE, obtaining mostly alkanes, alkenes and phenols [ 25 ]. Paula et al worked with mordenite, ZSM-5 and their alkali modifications for the pyrolysis of PP, PS and PE mixed plastics, obtaining more aromatic and light fraction compounds for the

[Find the meaning and references behind the names: Steel, Debris, Change, Plant, Purity, Ball, India, Cool, Nex, Raw, Left, Cao, Chosen, Wang, Stainless, Mesh, Mexico, Basic, Sio, Areas, Gel, Ray, Tio, Area, Table, Room, Aldrich, Barcelona, Fine, Mill, Quality, Austin, Kansas]

Sustainability 2024 , 16 , 5910 3 of 15 modified mordenite and a higher liquid fraction for the modified ZSM-5 [ 26 ]. Wang et al worked with PP to obtain abundant C 3–C 5 alkenes after its thermal pyrolysis, together with benzene, toluene and xylene (BTX) at a temperature of 300 ◦ C using the HZSM-5 zeolite [ 27 ]. This study presents an application of the catalytic pyrolysis of polypropylene to obtain the polymer precursor raw materials using synthetic zeolites prepared from natural precursors (pozzolana, pumice and ignimbrite). Those precursors were chosen as they are abundant in the southern Peruvian regions, being cheap and with suitable compositions for this application. The zeolitization of these precursors will improve the catalytic activity (cracking) and optimize chemical recycling alternatives for polymers in the country 2. Materials and Methods 2.1. Materials The zeolites were synthesized from three precursor materials such as pozzolana (PO), pumice (PU) and ignimbrite (IG), which were collected from different areas of the province of Arequipa (Peru). These 3 materials are abundant in the area. Composition of each precursor may change among different locations and it should be checked if a scalable process would be developed The collected precursor materials were initially conditioned by removing impurities (plant debris and rocks), then dried, crushed and subsequently ground in a ball mill. Then, they were sieved to obtain fine particles, using a sieve of mesh N ◦ . 140 (106 µ m). The raw material obtained after sieving was characterized by X-ray fluorescence (XRF), using a Rigaku NEX QC + QuantEZ dispersive fluorescence equipment (Austin, TX, USA). Table 1 shows the results obtained, with the three precursors having more than 87% silicon and aluminum oxides in their composition, which are the basic components for the synthesis of zeolites Table 1. Chemical composition of pozzolan, pumice and ignimbrite Oxide PO (%) PU (%) IG (%) SiO 2 77.90 78.60 67.60 Al 2 O 3 15.10 14.80 20.30 K 2 O 3.65 3.49 2.29 Fe 2 O 3 1.33 1.35 4.43 CaO 1.30 1.14 4.22 TiO 2 0.25 0.23 0.60 Others 0.47 0.39 0.56 All chemicals and reagents were used of analytical quality without further purification The materials used included NaOH (Scharlau, Barcelona, Spain), sodium silicate (Na 2 SiO 3 ) from Scharlab (Barcelona, Spain), tetrapropylammonium bromide (TPABr) at 98% purity (Sigma-Aldrich, Bangalore, India), concentrated sulfuric acid (H 2 SO 4 ) and NH 4 Cl from CV avantor (Ecatepec, Mexico), and commercial zeolite (ZSM-5) from Zeolyst International (Kansas City, MO, USA) 2.2. Zeolite Synthesis For the synthesis of the different zeolites, the procedure performed by Vichapund et al. [ 28 ] and Soongprasit et al. [ 29 ] was followed, with certain modifications. In total, 12 g of each precursor were mixed with 100 mL of NaOH (3 M) solution and stirred under a reflux condition at 60 ◦ C for 3 h to form a mixed solution of silicate and aluminate [ 29 ]. Then, over a period of 10 min at room temperature and under stirring, 31.9 g of Na 2 SiO 3 was added. Subsequently, 18.93 g of TPABr was added, fractionating the application to 0.42 g · min − 1 and then agitated for 3 h at room temperature. After agitation, the pH of the gel obtained was reduced to 11 with H 2 SO 4 , subjected to hydrothermal treatment in a Teflon-coated stainless steel autoclave at 160 ◦ C for 72 h and then left to cool at room

[Find the meaning and references behind the names: Step, Range, Band, Sabic, Final, Long, Tokyo, China, Gram, Elmer, Nir, Tube, Sample, Free, Non, Cuk, Image]

Sustainability 2024 , 16 , 5910 4 of 15 temperature overnight. Material was then washed and filtered until a pH < 9 was reached, and then it was dried in an oven at 100 ◦ C for 24 h. To remove the organic fraction of TPABr, it was then calcinated in a tubular furnace at 540 ◦ C for 5 h. With the intention of obtaining an acidified zeolite [ 28 ], the cooled product of the previous step was mixed with NH 4 Cl (1 M), in the following relation: 30 mL of NH 4 Cl for each gram of product. The obtained solution was subjected to reflux at 50 ◦ C for 4 h; then, filtration and washing were carried out in order to remove the chloride ions. The whole procedure was repeated, extending the stirring time to 6 h in this phase. To obtain final zeolites, the material was dried at 100 ◦ C for one night and then calcinated at 540 ◦ C for 5 h. The 3 zeolites obtained this way are labeled as HZ-PO (pozzolana zeolite), HZ-IG (ignimbrite zeolite) and HZ-PU (pumice zeolite) throughout the text The commercial zeolite (ZSM-5), the powdered precursor materials (PO, IG and PU) and the products obtained from the synthesis (HZ-PO, HZ-IG and HZ-PU) were subjected to Fourier Transform Infrared (FTIR) analysis, which was performed on a Perkin Elmer Frontier FT-IR/NIR model (Waltham, MA, USA), within a scanning range of 4000–650 cm − 1 In addition, in order to identify and characterize the crystalline phases, X-ray diffraction (XRD) tests were performed using a Rigaku Miniflex 600 X-ray diffractometer (Tokyo, Japan), which involved a source of radiation CuK α , measuring at 40 kV and 15 mA, in the 2 θ range of 3–90 ◦ . The morphological characteristics of the materials were analyzed using a Hitachi SU 8230 scanning electron microscope (Hitachi High-Tech, Tokyo, Japan), with backscattered electrons (BSE), with image magnifications of 20,000 × and 25,000 × 2.3. Catalytic Pyrolysis Catalytic pyrolysis was performed on 5707 N commercial polypropylene (PP) from SABIC (Ningbo, China) and was carried out in a 1 m long, 6 cm diameter quartz tube coupled to a horizontal tube furnace. The pyrolysis conditions were a temperature of 450 ◦ C and 30 min. For each sample, catalytic pyrolysis was replicated three times, varying the zeolite amount at 4, 6 and 8 wt.% in relation to the PP. N 2 was used, at a flow rate of 250 L · min − 1 , in order to have the chamber free of oxygen and avoid combustion reactions The sample was placed in a rectangular ceramic crucible containing PP mixed with the synthesized zeolite. The sample was introduced into the quartz tube for 30 min and the nitrogen flow was maintained. The gases generated were captured in the cooling system consisting of a gas trap immersed in liquid nitrogen. A fraction of the gases was condensed in the traps and the fraction of non-condensed gases was released. After the pyrolysis time had elapsed, the sample was removed to cool to room temperature and, finally, the products generated were classified into three groups: liquid products, gaseous products and residues. Then, the liquid fraction was characterized by Fourier Transform Infrared (FTIR), on a model machine the Perkin Elmer Frontier FT-IR/NIR model, within a scanning range of 4000–650 cm − 1 3. Results 3.1. FTIR in Precursors and Synthesized Zeolites The results of the characterization of the precursor materials, the synthesized zeolites and the commercial zeolite ZSM-5 are presented in Figure 1 within the range of the spectrum of 4500–650 cm − 1 . The spectra show prominent features attributed to silica and wastewater Table 2 summarizes the band peaks presented in all materials Band spectra in the range 1700–650 cm − 1 were magnified and superimposed in Figure 2 to differentiate the shift of the bands and the increase in the intensity of the peaks. The spectra of the precursor materials observed in the bands of the 1007 and 996 cm − 1 (Figures 1 and 2 ) correspond to the asymmetrical stretching vibrations of the T-O (T = Si or Al), as reported in other studies, being approximations [ 30 ] or within the range [ 31 ]. This would indicate the high concentration of silicon and aluminum, fundamental for the formation of zeolites, corroborating the XRF analysis (Table 1 ).

[Find the meaning and references behind the names: Stage, Mode, Double, Four, Rice, Magni, Peer, Ash, Dey, Success, Place, Case, Bonds, Small, Shown]

Sustainability 2024 , 16 , 5910 5 of 15 The band range between 1200 and 650 cm − 1 , which is shown in Figures 1 and 2 , relates to Si-O-T vibrations, taking place in the tetrahedral TO 4 mode for the synthesized zeolites [ 32 ]. The peaks of higher intensity in the synthesized zeolites located within the band range of 1075–1024 cm − 1 are related to the internal asymmetric stretching vibrations of the Si-O-T. In addition, these peaks (in the case of HZ-PO, HZ-IG and ZSM-5) are accompanied by shoulders in the 1210, 1219 and 1222 cm − 1 bands, respectively, corresponding to the external asymmetric stretching vibrations of structures containing four fivemembered ring chains arranged around a double screw axis [ 33 ]. The peaks in the range of 784–790 cm − 1 found in ZSM-5, HZ-IG, HZ-PU and HZ-PO zeolites correspond to the external symmetrical stretching vibrations of Si-O-T [ 34 ], as reported by Dey [ 35 ] for the ZSM-5 zeolites obtained from rice husk ash. The presence of peaks near the 1220, 1080 and 790 cm − 1 bands represents the formation of ZSM-5 type zeolites [ 33 , 35 , 36 ], with HZ-IG and HZ-PO zeolites showing the greatest similarity and which would represent the greatest success in the synthesis of this type of zeolites Sustainability 2024 , 16 , x FOR PEER REVIEW 5 of 17 Table 2. Characteristic FTIR bands of the synthesized zeolites, where T is Si or Al. Material/Zeolite Bending Stretching H-O-H Asymmetric Stretching Si-O-T Symmetric Stretching Si-O-T cm − 1 cm − 1 cm − 1 cm − 1 PO - 1007 780 724 IG - 1007 792 729 PU - 996 - 705 HZ-PO 1629 1052 785 - HZ-IG 1626 1065 793 - HZ-PU 1630 1024 787 722 ZSM-5 1620 1075 798 - Figure 1. FTIR of precursor materials (PO, IG, PU), synthesized zeolites (HZ-PO, HZ-IG, HZ-PU) and commercial ZSM-5. Band spectra in the range 1700–650 cm − 1 were magni fi ed and superimposed in Figure 2 to di ff erentiate the shift of the bands and the increase in the intensity of the peaks. The spectra of the precursor materials observed in the bands of the 1007 and 996 cm − 1 (Figures 1 and 2) correspond to the asymmetrical stretching vibrations of the T-O (T = Si or Al), as reported in other studies, being approximations [30] or within the range [31]. This would indicate the high concentration of silicon and aluminum, fundamental for the formation of zeolites, corroborating the XRF analysis (Table 1). Figure 1. FTIR of precursor materials (PO, IG, PU), synthesized zeolites (HZ-PO, HZ-IG, HZ-PU) and commercial ZSM-5 The presence of peaks in the band range 1618–1632 cm − 1 in the synthesized zeolites and ZSM-5 is related to the H-O-H stretching and bending vibrations, which correspond to the water absorbed in the structure [ 30 , 37 , 38 ]. This could have occurred in the synthesis process, specifically in the washing stage, and its low intensity would indicate a small presence of water since most of it was removed in the drying and calcination processes The presence of water in the structure can modify the zeolite skeleton upon temperature increase, causing hydrolysis of Si-O-Al bonds and removal of Al by dehydroxyla-

[Find the meaning and references behind the names: Tion, Ance, Cally, Share, Angles, Fly, Halo, Positive]

Sustainability 2024 , 16 , 5910 6 of 15 tion [ 39 ]. The removal of aluminum would lead to an increase in the Si/Al ratio and, consequently, to an increase in zeolite acidity Table 2. Characteristic FTIR bands of the synthesized zeolites, where T is Si or Al Material/Zeolite Bending Stretching H-O-H Asymmetric Stretching Si-O-T Symmetric Stretching Si-O-T cm − 1 cm − 1 cm − 1 cm − 1 PO - 1007 780 724 IG - 1007 792 729 PU - 996 - 705 HZ-PO 1629 1052 785 - HZ-IG 1626 1065 793 - HZ-PU 1630 1024 787 722 ZSM-5 1620 1075 798 - Sustainability 2024 , 16 , x FOR PEER REVIEW 6 of 17 Figure 2. FTIR transmi tt ance spectra, in the range of band 1700 – 650 cm − 1 . The band range between 1200 and 650 cm − 1 , which is shown in Figures 1 and 2, relates to Si-O-T vibrations, taking place in the tetrahedral TO 4 mode for the synthesized zeolites [32]. The peaks of higher intensity in the synthesized zeolites located within the band range of 1075–1024 cm − 1 are related to the internal asymmetric stretching vibrations of the Si-O-T. In addition, these peaks (in the case of HZ-PO, HZ-IG and ZSM-5) are accompanied by shoulders in the 1210, 1219 and 1222 cm − 1 bands, respectively, corresponding to the external asymmetric stretching vibrations of structures containing four fi ve-membered ring chains arranged around a double screw axis [33]. The peaks in the range of 784–790 cm − 1 found in ZSM-5, HZ-IG, HZ-PU and HZ-PO zeolites correspond to the external symmetrical stretching vibrations of Si-O-T [34], as reported by Dey [35] for the ZSM-5 zeolites obtained from rice husk ash. The presence of peaks near the 1220, 1080 and 790 cm − 1 bands represents the formation of ZSM-5 type zeolites [33,35,36], with HZ-IG and HZ-PO zeolites showing the greatest similarity and which would represent the greatest success in the synthesis of this type of zeolites. The presence of peaks in the band range 1618–1632 cm − 1 in the synthesized zeolites and ZSM-5 is related to the H-O-H stretching and bending vibrations, which correspond to the water absorbed in the structure [30,37,38]. This could have occurred in the synthesis process, speci fi cally in the washing stage, and its low intensity would indicate a small presence of water since most of it was removed in the drying and calcination processes. The presence of water in the structure can modify the zeolite skeleton upon temperature increase, causing hydrolysis of Si-O-Al bonds and removal of Al by dehydroxylation [39]. The removal of aluminum would lead to an increase in the Si/Al ratio and, consequently, to an increase in zeolite acidity. 3.2. XRD Figure 3 shows the XRD pa tt erns of the precursor minerals. The peaks that appear in the PO precursor are mainly crystalline phases of anorthoclase, muscovite and albite; in the IG precursor, the main crystalline phase is also anorthoclase, followed by cristobalite and albite. On the other hand, the main crystalline phase in PU is pyrite, followed by tremolite and anorthoclase. In the study by Vichaphund et al. [28] to synthesize zeolites Figure 2. FTIR transmittance spectra, in the range of band 1700–650 cm − 1 3.2. XRD Figure 3 shows the XRD patterns of the precursor minerals. The peaks that appear in the PO precursor are mainly crystalline phases of anorthoclase, muscovite and albite; in the IG precursor, the main crystalline phase is also anorthoclase, followed by cristobalite and albite. On the other hand, the main crystalline phase in PU is pyrite, followed by tremolite and anorthoclase. In the study by Vichaphund et al. [ 28 ] to synthesize zeolites from a fly ash precursor, quartz was the main crystalline phase. Although the three selected precursors used for zeolite synthesis have differences, they share in common that their crystalline phases present mainly silicon and aluminum. Anorthoclase is the crystalline phase that exists in the greatest amount of the three precursors studied. It is a feldspar consisting of aluminum silicates combined with varying percentages of potassium, sodium and calcium [ 40 , 41 ]. Likewise, from the precursor patterns shown in Figure 3 , it can also be noted that the peaks are mainly located between the angles 15 ◦ and 40 ◦ (2 θ ). The presence of the open halo, especially in PU and PO, would also indicate the presence of thermodynamically metastable amorphous aluminosilicate structures with high pozzolanic activity [ 3 ]. Considering the above, positive results can be expected for obtaining zeolites since the basis of the synthesis consists of using the characteristics of silicon and aluminum,

[Find the meaning and references behind the names: Alkaline, Less, Broad, Ojha, Verrecchia, Still, General, Peak]

Sustainability 2024 , 16 , 5910 7 of 15 which easily dissolve in an alkaline solution [ 4 ]. Furthermore, this assumption is also supported by the studies of Rajakrishnamoorthy et al. [ 42 ] and Verrecchia et al. [ 43 ], to obtain ZSM-5 and NaX zeolites, respectively, from fly ash, showing both of them XRD patterns with crystalline phases of silicon and aluminum, whose peaks were also in the range of 15 ◦ –40 ◦ (2 θ ) Sustainability 2024 , 16 , x FOR PEER REVIEW 8 of 17 the one that is closer to the commercial zeolite. This result shows that the used synthesis suits PO the best, while it scarcely performs on PU. The fact that crystalline phases of greater intensity were obtained in PO and IG could be due to the fact that they presented in their chemical composition a greater amount of Al 2 O 3 , since according to the study of Shigemoto et al. [49], Na-A zeolites were obtained that increased their crystallinity with the increase in the added NaAlO 2 content. From this result, it can be assumed that the type of precursor in fl uences the results of zeolite synthesis. In general, it can be clearly seen that the zeolites synthesized show higher crystallinity and less amorphous phases than their precursors. Figure 3. XRD pa tt erns of PO, IG and PU mineral precursors, and main crystalline phases found. Figure 3. XRD patterns of PO, IG and PU mineral precursors, and main crystalline phases found It can also be seen in Figure 3 that, among studied precursors, IG presents peaks of greater intensity, followed by PO and, with less intensity, PU. The latter presents more amorphous phases, resulting in the precursor with the lowest crystallinity [ 44 ]. This is also confirmed in the study by Wu et al. [ 4 ], showing that amorphous phases were predominant in the XRD pattern of pumice, with no evident peak, but a broad one from 10 ◦ to 40 ◦ (2 θ ) Figure 4 shows the XRD patterns of the synthesized zeolites and the commercial ZSM-5. It can be observed that the intensity of the anorthoclase and the other crystalline phases have decreased since those peaks are no longer visually prominent. Instead, new peaks, with higher intensity, appear. Likewise, the HZ-PO shows a greater reduction in the anorthoclase intensity; on the other hand, for the HZ-IG and HZ-PU, this peak is also reduced, but it is still maintained. This reduction in the initial crystalline phases may be due to the dissolution of the precursors with an alkaline solution, which contributes to the increase in silicate and aluminate solutions present in the HZ-IG and HZ-PU [ 28 ]. The assumption is supported by the results of the study by Ojha et al. [ 45 ], where a reduction in quartz and mullite intensity after the synthesis process using NaOH was also observed On the other hand, the XRD patterns of the three synthesized zeolites show the appearance of peaks between 7 ◦ and 9 ◦ and between 22 ◦ and 25 ◦ (2 θ ), similar to the peaks presented by the commercial zeolite used in the present study. Those peaks are characteristic of the presence of ZSM-5 zeolite structures [ 31 , 46 ], and these ranges are shaded in Figure 4 . Likewise, Soongprasit et al. [ 29 ] found XRD peaks at the same 2 θ range (assigned to JCPDS 44-0003). However, Yu et al. [ 47 ] found XRD peaks of their synthesized zeolites located at those mentioned ranges and argued that they correspond to the characteristic peaks of the MFI (inverted mordenite framework) structure type of HZSM-5, indicating the formation of HZSM-5. This is supported by Zang et al. [ 22 ] and Rajaei et al. [ 48 ]. Thus, everything would indicate that, in the present study, it has been possible to synthesize zeolites of the HZSM-5 type, which is the protonated ZSM-5 zeolite.

[Find the meaning and references behind the names: Quite, Mtt, Ern, Tun, Sousa, Movil, Original, Few, Simple, Fared, Mean, Ion, Iza, Ton]

Sustainability 2024 , 16 , 5910 8 of 15 Sustainability 2024 , 16 , x FOR PEER REVIEW 9 of 17 Figure 4. XRD pa tt erns of synthesized zeolites HZ-PO, HZ-IG y HZ-PU. 3.3. SEM Analysis The SEM images of the natural precursors and the synthesized zeolites are shown in Figure 5. The amorphous structures are evident, with the presence of fl a tt ened layers and irregular crystals of di ff erent sizes for the precursors (PO (Figure 5 A), IG (Figure 5 B) and PU (Figure 5 C)). After the alkaline hydrothermal synthesis process, those mineral precursors formed ordered structures according to their silica-alumina proportions [50,51]. This can be seen for HZ-PO (Figure 5 D), which had pozzolan as a precursor and presented abundant consolidated structures with an elongated hexagonal morphology of di ff erent sizes (between 2 and 3 µm). This form is typical for MFI (mobile fi ve-membered ring)-, TON (Theta One Niner)- and MTT (Movil to TUN)-type structures. Those acicular crystalline aggregates (rods) are also similar to ZSM-5 and ZSM-22 [52]. Kocirik et al. found the same mean MFI pa tt ern for Silicalica-1, which shares structure with ZSM-5, according to the International Zeolite Association (IZA) [53]. Verboekend et al. and Sousa et al. found that the intergrown phases between ZSM-5 and ZSM-22 by desilication had an in fl uence on the formation of phases under simple synthesis conditions [54,55], since the structure of ZSM-22 and ZSM-23 zeolites, when having a longer duration in time in its crystallization phase, favors the formation of the mineral cristobalite and broadens the synthetic range for ZSM-5 [56,57]. For HZ-IG zeolite (Figure 5 E), which had ignimbrite as a precursor, it fared relatively be tt er. Although it presented a considerable amount of amorphous material in the form of grains, the zeolitized section had a hexagonal morphology (co ffi ns) of approximately 1 µm, typical of ZSM-5 zeolite as mentioned in the study of Krisnandi et al. [31]. This type of zeolite was also synthesized by Yu et al. establishing a hierarchical HZSM-5 mesopore between 2 and 6 µm [47]. On the contrary, the zeolite HZ-PU (Figure 5 F), which had pumice with a very evident vitreous form as a precursor, did not zeolitize in its totality in consolidated structures and formed very few elongated hexagonal structures of approximately 2 µm typical of the zeolites ZSM-5 and ZSM-22. Quite amorphous material remains in the shape of columns similar to its precursor. The previous results were compared with the SEM images of the commercial zeolite ZSM-5 (Figure 5 G) which presented the typical co ffi n shape, a hexagonal morphology of approximately 120 nm in size; comparable results found by Zang et al. with a mean size of 40 nm con fi rmed the presence of MFI type zeolites [22]. Figure 4. XRD patterns of synthesized zeolites HZ-PO, HZ-IG y HZ-PU According to Figure 4 and considering the shaded ranges, it is confirmed that, after the synthesis process, new crystalline phases corresponding to zeolite HZSM-5 have formed, which are not observed in the XRD patterns of the precursors. These results are due to the specific synthesis process of the precursors: they are placed in a NaOH solution which destroys the original structure and, when heated, a new mineral phase is formed by crystallization [ 4 ]. Finally, using NH 4 Cl resulted in the zeolite acquiring that acidic character, which is known as the ion exchange method and was similarly used by Rajaei et al. [ 48 ] to protonate ZSM-5 but making use of NH 4 NO 3 In Figure 4 , it can be observed that the HZ-PO zeolite presents peaks of higher intensity, followed by HZ-IG, and HZ-PU showing the lowest intensity, which would indicate that the synthesized HZ-PO zeolite is the one that presents higher crystallinity [ 31 ] and the one that is closer to the commercial zeolite. This result shows that the used synthesis suits PO the best, while it scarcely performs on PU. The fact that crystalline phases of greater intensity were obtained in PO and IG could be due to the fact that they presented in their chemical composition a greater amount of Al 2 O 3 , since according to the study of Shigemoto et al. [ 49 ], Na-A zeolites were obtained that increased their crystallinity with the increase in the added NaAlO 2 content. From this result, it can be assumed that the type of precursor influences the results of zeolite synthesis. In general, it can be clearly seen that the zeolites synthesized show higher crystallinity and less amorphous phases than their precursors 3.3. SEM Analysis The SEM images of the natural precursors and the synthesized zeolites are shown in Figure 5 . The amorphous structures are evident, with the presence of flattened layers and irregular crystals of different sizes for the precursors (PO (Figure 5 A), IG (Figure 5 B) and PU (Figure 5 C)). After the alkaline hydrothermal synthesis process, those mineral precursors formed ordered structures according to their silica-alumina proportions [ 50 , 51 ]. This can be seen for HZ-PO (Figure 5 D), which had pozzolan as a precursor and presented abundant consolidated structures with an elongated hexagonal morphology of different sizes (between 2 and 3 µ m). This form is typical for MFI (mobile five-membered ring)-, TON (Theta One Niner)- and MTT (Movil to TUN)-type structures. Those acicular crystalline aggregates (rods) are also similar to ZSM-5 and ZSM-22 [ 52 ]. Kocirik et al. found the same mean MFI pattern for Silicalica-1, which shares structure with ZSM-5, according to the International Zeolite Association (IZA) [ 53 ]. Verboekend et al. and Sousa et al. found that the intergrown phases between ZSM-5 and ZSM-22 by desilication had an influence on the formation of phases under simple synthesis conditions [ 54 , 55 ], since the structure of

[Find the meaning and references behind the names: Joyner, Coffin, Teller, Barre, Emme]

Sustainability 2024 , 16 , 5910 9 of 15 ZSM-22 and ZSM-23 zeolites, when having a longer duration in time in its crystallization phase, favors the formation of the mineral cristobalite and broadens the synthetic range for ZSM-5 [ 56 , 57 ]. For HZ-IG zeolite (Figure 5 E), which had ignimbrite as a precursor, it fared relatively better. Although it presented a considerable amount of amorphous material in the form of grains, the zeolitized section had a hexagonal morphology (coffins) of approximately 1 µ m, typical of ZSM-5 zeolite as mentioned in the study of Krisnandi et al. [ 31 ]. This type of zeolite was also synthesized by Yu et al. establishing a hierarchical HZSM-5 mesopore between 2 and 6 µ m [ 47 ]. On the contrary, the zeolite HZ-PU (Figure 5 F), which had pumice with a very evident vitreous form as a precursor, did not zeolitize in its totality in consolidated structures and formed very few elongated hexagonal structures of approximately 2 µ m typical of the zeolites ZSM-5 and ZSM-22. Quite amorphous material remains in the shape of columns similar to its precursor. The previous results were compared with the SEM images of the commercial zeolite ZSM-5 (Figure 5 G) which presented the typical coffin shape, a hexagonal morphology of approximately 120 nm in size; comparable results found by Zang et al. with a mean size of 40 nm confirmed the presence of MFI type zeolites [ 22 ]. Sustainability 2024 , 16 , x FOR PEER REVIEW 10 of 17 Figure 5. SEM images of natural precursors: ( A ) pozzolana PO, ( B ) ignimbrite IG, ( C ) pumice, PU; synthesized zeolites ( D ) HZ-PO, ( E ) HZ-IG, ( F ) HZ-PU and ( G ) ZSM-5. 3.4. BET Analysis Table 3 summarizes the textural characteristics obtained by the Brunauer–Emme tt – Teller (BET) and Barre tt –Joyner–Halenda (BJH) methods. As can be observed, the HZ-PO zeolite is the one that presents a higher speci fi c surface area, but a smaller pore diameter. For the HZ-PU zeolite, the opposite occurs: a lower speci fi c surface area, a larger pore diameter and additionally smaller micropore area and volume compared to the others. Figure 5. SEM images of natural precursors: ( A ) pozzolana PO, ( B ) ignimbrite IG, ( C ) pumice, PU; synthesized zeolites ( D ) HZ-PO, ( E ) HZ-IG, ( F ) HZ-PU and ( G ) ZSM-5.

[Find the meaning and references behind the names: Makes, Barrett, Wax, Cases, Char, Emmett]

Sustainability 2024 , 16 , 5910 10 of 15 3.4. BET Analysis Table 3 summarizes the textural characteristics obtained by the Brunauer–Emmett– Teller (BET) and Barrett–Joyner–Halenda (BJH) methods. As can be observed, the HZ-PO zeolite is the one that presents a higher specific surface area, but a smaller pore diameter. For the HZ-PU zeolite, the opposite occurs: a lower specific surface area, a larger pore diameter and additionally smaller micropore area and volume compared to the others Table 3. Textural properties of the synthesized zeolites Zeolite Surface Specific Area Micropore Area Micropore Volume Pore Diameter m 2 /g m 2 /g cm 3 /g nm HZ-PO 229 144 0.076 3.8 HZ-IG 205 147 0.076 4.8 HZ-PU 156 101 0.053 5.8 The HZ-PO and HZ-IG zeolites present a high specific surface area while HZ-PU has a moderate one. All zeolites have a relatively low porosity (low pore volume), with mesopores predominating. Compared to the textural properties found in other research about the synthesis of ZSM-5 zeolites, it was found that the specific surface area and pore diameter range from 329 m 2 /g and 3.7 nm [ 29 ] to 453 m 2 /g and 3.3 nm [ 28 ], which makes a considerable difference to those synthesized in this research 3.5. Pyrolysis Products Figure 6 shows the distribution of the products obtained after the pyrolysis of PP using three different amounts (4, 6 and 8 wt.%) of the synthesized zeolites, as well as the products using the ZSM-5 commercial zeolite and the products obtained after a conventional thermal pyrolysis process Sustainability 2024 , 16 , x FOR PEER REVIEW 12 of 17 Figure 6. Percentage of pyrolysis products by using synthesized zeolites, commercial zeolite and thermal pyrolysis. Figure 6. Percentage of pyrolysis products by using synthesized zeolites, commercial zeolite and thermal pyrolysis Thermal pyrolysis (when no catalyst is used) produces a high amount of wax, and hence low percentages of liquid and gas. The use of zeolites varies the distribution, helping in some cases to obtain better products. However, it can be seen that the use of zeolites at 4% by weight does not change very much the obtained products when compared to those of thermal pyrolysis, since even slightly more wax is produced with HZ-IG and HZ-PU In all cases (thermal and catalytic pyrolysis), the amount of solids (Char) produced is always below 0.5%, without any noticeable difference among studied conditions. The

[Find the meaning and references behind the names: Ole, Panda, Plane, Chain, Tekin, Wong, Zhou, Bond, Rolling]

Sustainability 2024 , 16 , 5910 11 of 15 fact that synthesized catalysts do not promote the formation of greater amounts of char is positive Increasing the proportion of zeolite from 4 to 8% decreases the amount of wax, indicating a better performance of zeolites when increasing the amount of catalyst. The maximum yield for liquid products is obtained for 8% of HZ-PO. In the case of HZ-PU, the amount of liquids is similar for the three percentages, although slightly higher for 4%. In the case of gases, the maximum yield for HZ-IG and HZ-PU is obtained for 8% addition, while the maximum yield for HZ-PO is 6%. Considering together the amount of gas and liquid produced and these being the main products to be obtained, it could be said that, in general, the best results are obtained for 8% of zeolite. Taking, then, into account that 8% of zeolite is necessary to obtain better pyrolysis products, HZ-PU stands out among the three synthetic zeolites, followed by HZ-IG However, although the three synthesized zeolites improve the results of the pyrolysis products when compared to thermal decomposition, they did not reach the efficiency of the commercial ZSM-5 zeolite, which shows higher percentages of liquid and gas with very little presence of wax. This may be due to the fact that the same textual characteristics of porosity and surface area of a ZSM-5 were not obtained [ 29 ]. This is supported by the study of Wong et al. [ 58 ] about PP pyrolysis with ZSM-5, obtaining up to 75.2% by weight of gas, up to 35.9% by weight of liquid and a low percentage of wax, similar to the majority of tests carried out. On the other hand, Zhou et al. [ 59 ] obtained good results when using ZSM-5 on polypropylene, where more liquid than gas was generated, which may be due to the different microwave-assisted pyrolysis methods 3.6. Analysis of Pyrolysis Liquid Products Qualitatively, the three FTIR spectra of the liquid products of pyrolysis with the synthesized zeolites present similar characteristic bands, with slight differences, as can be seen in Figure 7 . The assignment of bands is indicated in Table 4 . Sustainability 2024 , 16 , x FOR PEER REVIEW 13 of 17 3.6. Analysis of Pyrolysis Liquid Products Qualitatively, the three FTIR spectra of the liquid products of pyrolysis with the synthesized zeolites present similar characteristic bands, with slight di ff erences, as can be seen in Figure 7. The assignment of bands is indicated in Table 4. Figure 7. FTIR transmi tt ance spectra of pyrolysis oils from PP with 8% zeolites. Table 4. Functional groups from FTIR spectra of PP pyrolysis oils. Bands (cm − 1 ) Bond Functional Group 2957 Asymmetric C-H stretching of CH 3 Methyl-alkanes 2925, 2924 Asymmetric C-H stretching of CH 3 Methyl-alkanes 2872, 2871 Symmetric stretching C-H of CH 3 Methyl-alkanes 1650 Stretching C=C Alkenes 1458, 1457 Asymmetric bending C-H of CH 3 ; flexion in the plane C-H (scissoring) of CH 2 Methyl and methylene Alkanes 1378 Symmetric C-H bending of CH 3 Methyl-alkanes 967, 966 C-H bending Alkenes 888 Flexion out of the C-H plane Alkenes 795 Flexion out of the C-H plane Aromatics 728 Bending in the plane C-H (rolling) of CH 2 Methyl-alkanes 694 Flexion out of the C-H plane Aromatics The analysis reveals that the composition of the oils is largely dominated by para ffi ns followed by ole fi ns. There is li tt le presence of aromatics, and this can be explained by the absence of aromatic rings in the polymer main chain. Similar results were reported by Panda et al. [60] after the individual pyrolysis of PP. On the other hand, Miandad et al. [61] reported a composition of kerosenes, ole fi ns, aldehydes and aromatics, being this a very complex composite composition. The result of the la tt er study may be due to the type of pyrolysis, which was exclusively thermal. Also, Tekin et al. [62] obtained similar results, Figure 7. FTIR transmittance spectra of pyrolysis oils from PP with 8% zeolites.

[Find the meaning and references behind the names: Salt, Ones]

Sustainability 2024 , 16 , 5910 12 of 15 Table 4. Functional groups from FTIR spectra of PP pyrolysis oils Bands (cm − 1 ) Bond Functional Group 2957 Asymmetric C-H stretching of CH 3 Methyl-alkanes 2925, 2924 Asymmetric C-H stretching of CH 3 Methyl-alkanes 2872, 2871 Symmetric stretching C-H of CH 3 Methyl-alkanes 1650 Stretching C=C Alkenes 1458, 1457 Asymmetric bending C-H of CH 3 ; flexion in the plane C-H (scissoring) of CH 2 Methyl and methylene Alkanes 1378 Symmetric C-H bending of CH 3 Methyl-alkanes 967, 966 C-H bending Alkenes 888 Flexion out of the C-H plane Alkenes 795 Flexion out of the C-H plane Aromatics 728 Bending in the plane C-H (rolling) of CH 2 Methyl-alkanes 694 Flexion out of the C-H plane Aromatics The analysis reveals that the composition of the oils is largely dominated by paraffins followed by olefins. There is little presence of aromatics, and this can be explained by the absence of aromatic rings in the polymer main chain. Similar results were reported by Panda et al. [ 60 ] after the individual pyrolysis of PP. On the other hand, Miandad et al. [ 61 ] reported a composition of kerosenes, olefins, aldehydes and aromatics, being this a very complex composite composition. The result of the latter study may be due to the type of pyrolysis, which was exclusively thermal. Also, Tekin et al. [ 62 ] obtained similar results, although with a reduction in olefinic compounds due to the use of the AlCl 3 basic salt catalyst Figure 7 shows the disappearance of the characteristic peaks of the aromatics (795 and 694 cm − 1 ) and the reduction in the intensity of the 728 cm − 1 band in the spectrum of the HZ-PU (8%) zeolite product, which would indicate that this zeolite tends to produce compounds clearly from the alkane and alkene family 4. Conclusions It was possible to synthesize zeolites similar to commercial ZSM-5. Probably, they are found in a protonated form (as HZSM-5) due to the use of NH 4 Cl during the synthesis The precursors considered were favorable for their high content of aluminosilicates, fundamental for the formation of zeolites, resulting in synthesis success, particularly for the IG and PO precursors, according to XRD and FTIR The SEM analysis indicates that the shapes obtained after the hydrothermal synthesis process are typical of the MFI structures for HZ-IG (ignimbrite), which has the greatest similarity to the ZSM-5 zeolite, followed by HZ-PO (pozzolana) and finally HZ-PU (pumice) with a higher amorphous index. According to the BET analysis, zeolites formed with ignimbrite and pozzolana precursors were the ones that obtained the highest specific surface area, and due to their pore size, they are considered mesopores and are very comparable to ZSM-5 According to the results obtained from pyrolysis, regardless of whether it is thermal or catalytic, the production of solids was minimal. When using the catalyst, it was evidenced that wax production was lower than in thermal pyrolysis, except when working at 4% with HZ-PU and HZ-IG. With respect to the amount of zeolite, it was concluded that 8% of zeolite decreased the amount of wax and increased the production of liquid-gas, for all the zeolites used. The highest liquid production was 29.42% and 52.91% in gas with 8% of HZ-PU. However, these results are slightly insufficient in relation to the results achieved by ZSM-5 which had a minimum presence of waxes and higher percentages of liquid and gas, which indicates a better cracking of the polymer. The closest to this result is the HZ-PU and, in general, the use of these zeolites synthesized improved the production of liquids and gases.

[Find the meaning and references behind the names: Eng, Zhang, Ortiz, Resources, Wiley, Iba, Rimer, Song, Wen, Pir, Board, Nico, Amal, Dong, Miner, Zeng, Soc, Gao, Eco, Hsu, Gil, Urban, Sons, Vargas, Scott, Read, John, Zeyad, Chem, Pol, Berlin, Elangovan, Masini, Jain, Joca, Germany, Torres, Almalki, Nez, Data, Zhu, Toc, Arab, Cataldo, Beta, Guang, Catal, Mico, Mater, Prod, Progress, Tulloch, Gob, Salvi, Mart, Role, Thank, Peng, Valdivia, Chen, Vaughan, Author, Fucile, Zardo, Tica, Paoli, Prd, Lima, Lava, Manzi, Springer]

Sustainability 2024 , 16 , 5910 13 of 15 Author Contributions: Conceptualization, S.H.F.-M., A.G.V.-H. and L.F.M.-D.L.C.; methodology, S.H.F.-M., A.G.V.-H. and L.F.M.-D.L.C.; software, S.H.F.-M., A.G.V.-H. and L.F.M.-D.L.C.; validation, J.A., R.C. and F.V.; formal analysis, J.A.; investigation, S.H.F.-M., A.G.V.-H. and L.F.M.-D.L.C.; resources, J.A., R.C., A.S.-V. and J.M.-Q.; data curation, R.C.; writing—original draft preparation, S.H.F.-M., A.G.V.-H. and L.F.M.-D.L.C.; writing—review and editing, J.A., R.C. and F.V.; visualization, R.C. and F.V.; supervision, J.A.; project administration, J.A.; funding acquisition, J.A. All authors have read and agreed to the published version of the manuscript Funding: This research was financed by the Universidad Nacional de San Agust í n de Arequipa-Per ú with the project: “Obtenci ó n de Zeolitas a partir de Materiales Naturales de Origen Volc á nico para Aplicaci ó n en Pir ó lisis Catal í tica para el Reciclaje Qu í mico Sostenible de Pol í meros” (contract number: IBA-IB-39-2020-UNSA) Institutional Review Board Statement: Not applicable Informed Consent Statement: Not applicable Data Availability Statement: The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author Acknowledgments: The authors thank the National University of San Agust í n de Arequipa through Contract N ◦ IBA-IB-39-2020-UNSA for its funding of this research Conflicts of Interest: The authors declare no conflicts of interest. The funders had no role in the design of the study, in the collection, analyses, or interpretation of data, in the writing of the manuscript, or in the decision to publish the results References 1 Ingemmet. ¿Por qu é en Per ú no son frecuentes las erupciones con flujos de lava? Ingemmet. Available online: https://www.gob. pe/institucion/ingemmet/noticias/494029-por-que-en-peru-no-son-frecuentes-las-erupciones-con-flujos-de-lava (accessed on 13 June 2023) 2 Zeyad, A.M.; Almalki, A. Role of particle size of natural pozzolanic materials of volcanic pumice: Flow properties, strength, and permeability Arab. J. Geosci 2021 , 14 , 107. [ CrossRef ] 3 Churata, R.; Almir ó n, J.; Vargas, M.; Tupayachy-Quispe, D.; Torres-Almir ó n, J.; Ortiz-Valdivia, Y.; Velasco, F. Study of Geopolymer Composites Based on Volcanic Ash, Fly Ash, Pozzolan, Metakaolin and Mining Tailing Buildings 2022 , 12 , 1118. [ CrossRef ] 4 Wu, T.-L.; Chen, Y.-H.; Hsu, W.-D. Phase transition pathway of hydrothermal zeolite synthesis Phys. Chem. Miner 2021 , 48 , 1 [ CrossRef ] 5 Lima, R.C.; Bieseki, L.; Melguizo, P.V.; Pergher, S.B.C. Zeolite Eco-friendly Synthesis. In Engineering Materials ; Springer Science and Business Media B.V.: Berlin/Heidelberg, Germany, 2019; pp. 65–91. [ CrossRef ] 6 Research and Markets. Zeolite Market: Global Industry Trends, Share, Size, Growth, Opportunity and Forecast 2023–2028. Research and Markets. Available online: https://www.researchandmarkets.com/reports/5820578/zeolite-market-globalindustry-trends-share?utm_code=fxhbx 3&utm_exec=joca 220 prd#product--toc (accessed on 13 June 2023) 7 Yoldi, M.; Fuentes-Ordoñez, E.; Korili, S.; Gil, A. Zeolite synthesis from industrial wastes Microporous Mesoporous Mater 2019 , 287 , 183–191. [ CrossRef ] 8 Gao, S.; Peng, H.; Song, B.; Zhang, J.; Wu, W.; Vaughan, J.; Zardo, P.; Vogrin, J.; Tulloch, S.; Zhu, Z. Synthesis of zeolites from low-cost feeds and its sustainable environmental applications J. Environ. Chem. Eng 2023 , 11 , 108995. [ CrossRef ] 9 Zaarour, M.; Dong, B.; Naydenova, I.; Retoux, R.; Mintova, S. Progress in zeolite synthesis promotes advanced applications Microporous Mesoporous Mater 2014 , 189 , 11–21. [ CrossRef ] 10 Jain, R.; Mallette, A.J.; Rimer, J.D. Controlling Nucleation Pathways in Zeolite Crystallization: Seeding Conceptual Methodologies for Advanced Materials Design J. Am. Chem. Soc 2021 , 143 , 21446–21460. [ CrossRef ] [ PubMed ] 11 Mart í nez, C.; Corma, A. Inorganic molecular sieves: Preparation, modification and industrial application in catalytic processes Coord. Chem. Rev 2011 , 255 , 1558–1580. [ CrossRef ] 12 Kamimura, Y.; Iyoki, K.; Elangovan, S.P.; Itabashi, K.; Shimojima, A.; Okubo, T. OSDA-free synthesis of MTW-type zeolite from sodium aluminosilicate gels with zeolite beta seeds Microporous Mesoporous Mater 2012 , 163 , 282–290. [ CrossRef ] 13 Williams, C.D. Application of Zeolites to Environmental Remediation. In Urban Pollution ; John Wiley & Sons, Ltd.: Chichester, UK, 2018; pp. 249–258. [ CrossRef ] 14 Scott, J.; Guang, D.; Naeramitmarnsuk, K.; Thabuot, M.; Amal, R. Zeolite synthesis from coal fly ash for the removal of lead ions from aqueous solution J. Chem. Technol. Biotechnol 2002 , 77 , 63–69. [ CrossRef ] 15 Wen, J.; Dong, H.; Zeng, G. Application of zeolite in removing salinity/sodicity from wastewater: A review of mechanisms, challenges and opportunities J. Clean. Prod 2018 , 197 , 1435–1446. [ CrossRef ] 16 Cataldo, E.; Salvi, L.; Paoli, F.; Fucile, M.; Masciandaro, G.; Manzi, D.; Masini, C.M.; Mattii, G.B. Application of Zeolites in Agriculture and Other Potential Uses: A Review Agronomy 2021 , 11 , 1547. [ CrossRef ]

[Find the meaning and references behind the names: Da Rosa, Ryabova, Saravanan, Neto, Shu, Real, Santos, Yanti, Class, Murti, Diaz, Caldeira, Marques, Life, Zhao, Ong, Asadi, Chung, Roudet, Jiang, Datta, Russ, Liang, Int, Wojciechowska, Adv, Sci, Boca, Flame, Fast, Dell, Power, Atong, Saito, Huang, Ser, Multi, Monteiro, Novel, Rosa, Eller, Bio, Rachman, Duquesne, Luo, Era, Brouwers, Frantz, Souza, Raton, State, Klima, Post, Ghosh, Wijaya, Naskar, Szostak, Kim, Saffar, Pan, Run, Ruiz, Karthikeyan, April, Clay, Jones, Oil, Flight, Scarsella, End, Yang, Deng, Cafiero, Cheng, Oliveira]

Sustainability 2024 , 16 , 5910 14 of 15 17 Datta, J.; Kopczy ´nska, P. From polymer waste to potential main industrial products: Actual state of recycling and recovering Crit Rev. Environ. Sci. Technol 2016 , 46 , 905–946. [ CrossRef ] 18 Jones, H.; Saffar, F.; Koutsos, V.; Ray, D. Polyolefins and Polyethylene Terephthalate Package Wastes: Recycling and Use in Composites Energies 2021 , 14 , 7306. [ CrossRef ] 19 Almir ó n, J.; Huaman, A.V.; Mamani, S.F.; De La Cruz, L.M. A review of the interaction of natural and synthetic zeolites in the pyrolysis of plastics. In Proceedings of the 20 th LACCEI International Multi-Conference for Engineering, Education and Technology: “Education, Research and Leadership in Post-Pandemic Engineering: Resilient, Inclusive and Sustainable Actions, Boca Raton, FL, USA, 18–22 July 2022 ; Latin American and Caribbean Consortium of Engineering Institutions: Arequipa, Peru, 2022. [ CrossRef ] 20 Al-Asadi, M.; Miskolczi, N.; Eller, Z. Pyrolysis-gasification of wastes plastics for syngas production using metal modified zeolite catalysts under different ratio of nitrogen/oxygen J. Clean. Prod 2020 , 271 , 122186. [ CrossRef ] 21 Miskolczi, N.; Juzsakova, T.; S ó ja, J. Preparation and application of metal loaded ZSM-5 and y-zeolite catalysts for thermo-catalytic pyrolysis of real end of life vehicle plastics waste J. Energy Inst 2019 , 92 , 118–127. [ CrossRef ] 22 Zang, Y.; Wang, J.; Gu, J.; Qu, J.; Gao, F.; Li, M. Cost-effective synthesis of hierarchical HZSM-5 with a high Si/TPA+ ratio for enhanced catalytic cracking of polyethylene J. Solid State Chem 2020 , 291 , 121643. [ CrossRef ] 23 Lima, R.B.; Neto, M.M.; Oliveira, D.S.; Santos, A.G.; Souza, L.D.; Caldeira, V.P. Obtainment of hierarchical ZSM-5 zeolites by alkaline treatment for the polyethylene catalytic cracking Adv. Powder Technol 2021 , 32 , 515–523. [ CrossRef ] 24 Instituto Nacional de Estadistica Informatica (INEI). Industria del Pl á stico en el Per ú . INEI. Available online: https://www.inei. gob.pe/media/MenuRecursivo/boletines/industria-plastico-peru.pdf (accessed on 4 April 2024) 25 Santoso, A.; Sholikhah, A.; Sumari, S.; Asrori, M.R.; Wijaya, A.R.; Retnosari, R.; Rachman, I.B. Effect of Active Zeolite in the Pyrolysis of Polypropylene and Low Density Polyethylene Types of Plastic Waste J. Renew. Mater 2022 , 10 , 2781–2789. [ CrossRef ] 26 Paula, T.P.; Marques, M.D.F.V.; Marques, M.R.D.C.; Oliveira, M.S.; Monteiro, S.N. Thermal and Catalytic Pyrolysis of Urban Plastic Waste: Modified Mordenite and ZSM-5 Zeolites Chemistry 2022 , 4 , 297–315. [ CrossRef ] 27 Wang, Y.; Huang, Q.; Zhou, Z.; Yang, J.; Qi, F.; Pan, Y. Online Study on the Pyrolysis of Polypropylene over the HZSM-5 Zeolite with Photoionization Time-of-Flight Mass Spectrometry Energy Fuels 2015 , 29 , 1090–1098. [ CrossRef ] 28 Vichaphund, S.; Aht-Ong, D.; Sricharoenchaikul, V.; Atong, D. Characteristic of fly ash derived-zeolite and its catalytic performance for fast pyrolysis of Jatropha waste Environ. Technol 2014 , 35 , 2254–2261. [ CrossRef ] [ PubMed ] 29 Soongprasit, K.; Sricharoenchaikul, V.; Atong, D. Pyrolysis of Millettia (Pongamia) pinnata waste for bio-oil production using a fly ash derived ZSM-5 catalyst J. Anal. Appl. Pyrolysis 2019 , 139 , 239–249. [ CrossRef ] 30 Gollakota, A.R.; Volli, V.; Munagapati, V.S.; Wen, J.-C.; Shu, C.-M. Synthesis of novel ZSM-22 zeolite from Taiwanese coal fly ash for the selective separation of Rhodamine 6 G J. Mater. Res. Technol 2020 , 9 , 15381–15393. [ CrossRef ] 31 Krisnandi, Y.K.; Yanti, F.M.; Murti, S.D.S. Synthesis of ZSM-5 zeolite from coal fly ash and rice husk: Characterization and application for partial oxidation of methane to methanol IOP Conf. Ser. Mater. Sci. Eng 2017 , 188 , 012031. [ CrossRef ] 32 Wojciechowska, K.M.; Kr ó l, M.; Bajda, T.; Mozgawa, W. Sorption of Heavy Metal Cations on Mesoporous ZSM-5 and Mordenite Zeolites Materials 2019 , 12 , 3271. [ CrossRef ] [ PubMed ] 33 Frantz, T.S.; Ruiz, W.A.; da Rosa, C.A.; Mortola, V.B. Synthesis of ZSM-5 with high sodium content for CO 2 adsorption Microporous Mesoporous Mater 2016 , 222 , 209–217. [ CrossRef ] 34 Szostak, R Molecular Sieves ; Springer: Dordrecht, The Netherlands, 1989. [ CrossRef ] 35 Dey, K.P.; Ghosh, S.; Naskar, M.K. Organic template-free synthesis of ZSM-5 zeolite particles using rice husk ash as silica source Ceram. Int 2013 , 39 , 2153–2157. [ CrossRef ] 36 Kim, D.J.; Chung, H.S. Synthesis and characterization of ZSM-5 zeolite from serpentine Appl. Clay Sci 2003 , 24 , 69–77. [ CrossRef ] 37 Liang, G.; Li, Y.; Yang, C.; Hu, X.; Li, Q.; Zhao, W. Synthesis of ZSM-5 zeolites from biomass power plant ash for removal of ionic dyes from aqueous solution: Equilibrium isotherm, kinetic and thermodynamic analysis RSC Adv 2021 , 11 , 22365–22375 [ CrossRef ] 38 Luo, W.; Yang, X.; Wang, Z.; Huang, W.; Chen, J.; Jiang, W.; Wang, L.; Cheng, X.; Deng, Y.; Zhao, D. Synthesis of ZSM-5 aggregates made of zeolite nanocrystals through a simple solvent-free method Microporous Mesoporous Mater 2017 , 243 , 112–118. [ CrossRef ] 39 Erofeev, V.I.; Adyaeva, L.V.; Ryabova, N.V. Effect of High-Temperature Steam Treatment of High-Silica Zeolites of the ZSM-5 Type on Their Acidity and Selectivity of Formation of Lower Olefins from Straight-Run Naphthas Russ. J. Appl. Chem 2003 , 76 , 95–98 [ CrossRef ] 40 Klima, K.; Schollbach, K.; Brouwers, H.; Yu, Q. Enhancing the thermal performance of Class F fly ash-based geopolymer by sodalite Constr. Build. Mater 2022 , 314 , 125574. [ CrossRef ] 41 Cruz S á nchez, E.; Torres, M.E.; Diaz, C.; Saito, F. Effects of grinding of the feldspar in the sintering using a planetary ball mill J Am. Acad. Dermatol 2004 , 152 , 284–290. [ CrossRef ] 42 Rajakrishnamoorthy, P.; Karthikeyan, D.; Saravanan, C. Emission reduction technique applied in SI engines exhaust by using zsm 5 zeolite as catalysts synthesized from coal fly ash Mater. Today Proc 2020 , 22 , 499–506. [ CrossRef ] 43 Verrecchia, G.; Cafiero, L.; de Caprariis, B.; Dell’Era, A.; Pettiti, I.; Tuffi, R.; Scarsella, M. Study of the parameters of zeolites synthesis from coal fly ash in order to optimize their CO 2 adsorption Fuel 2020 , 276 , 118041. [ CrossRef ] 44 Almir ó n, J.; Vargas, M.; Tupayachy-Quispe, D.; Duquesne, S.; Roudet, F.; Silva-Vela, A. Influence of the Process of Synthesis of Zeolites from Volcanic Ash in Its Synergistic Action as a Flame-Retardant for Polypropylene Composites Buildings 2021 , 12 , 24 [ CrossRef ]

[Find the meaning and references behind the names: Van Dyk, Liu, Lee, Pacheco, Transport, Abdullah, Singh, Ram, Ramadhani, Ismail, Thomas, Fang, Aluminium, Pradhan, Kumar, Armenise, Excellent, Nizami, Rehan, Prior, Nov, Zik, Elem, Dyk, Rez, Dai, Towers, Munusamy, Mowla, Arcanjo, Teixeira, Yamamoto, Ideas, Lett, Barakat, Ruan, Gilson, Crystal, Meng, Guo, Samanta, Green, Shibata, Rich, Pai, Lei, Hayashi, Property, Nano]

Sustainability 2024 , 16 , 5910 15 of 15 45 Ojha, K.; Pradhan, N.C.; Samanta, A.N. Zeolite from fly ash: Synthesis and characterization Bull. Mater. Sci 2004 , 27 , 555–564 [ CrossRef ] 46 Ramadhani, A.N.; Abdullah, I.; Krisnandi, Y.K. Effect of Physicochemical Properties of Co and Mo Modified Natural Sourced Hierarchical ZSM-5 Zeolite Catalysts on Vanillin and Phenol Production from Diphenyl Ether Bull. Chem. React. Eng. Catal 2022 , 17 , 225–239. [ CrossRef ] 47 Yu, D.; Chen, W.; Zhang, S.; Chilivery, R.; Li, F.; Lu, X.; Song, Y.; Fang, Y. Synthesis of HZSM-5 zeolites with excellent DME aromatization properties by orthogonal test Phosphorus Sulfur Silicon Relat. Elem 2020 , 195 , 464–473. [ CrossRef ] 48 Rajaei, H.; Esmaeilzadeh, F.; Mowla, D. Synthesis and Characterization of Nano-Sized Pt/HZSM–5 Catalyst for Application in the Xylene Isomerization Process Catal. Lett 2022 , 152 , 139–150. [ CrossRef ] 49 Shigemoto, N.; Hayashi, H.; Miyaura, K. Selective formation of Na-X zeolite from coal fly ash by fusion with sodium hydroxide prior to hydrothermal reaction J. Mater. Sci 1993 , 28 , 4781–4786. [ CrossRef ] 50 Zhang, K.; Van Dyk, L.; He, D.; Deng, J.; Liu, S.; Zhao, H. Synthesis of zeolite from fly ash and its adsorption of phosphorus in wastewater Green Process. Synth 2021 , 10 , 349–360. [ CrossRef ] 51 Murayama, N.; Yamamoto, H.; Shibata, J. Mechanism of zeolite synthesis from coal fly ash by alkali hydrothermal reaction Int. J Miner. Process 2002 , 64 , 1–17. [ CrossRef ] 52 Dai, S.; Tan, Y.; Yang, Y.; Zhu, L.; Liu, B.; Du, Y.; Cao, X. Organotemplate-free synthesis of Al-rich ZSM-35 and ZSM-22 zeolites with the addition of ZSM-57 zeolite seeds CrystEngComm 2022 , 24 , 6987–6995. [ CrossRef ] 53 Kocirik, M.; Kornatowski, J.; Masaˇr í k, V.; Nov á k, P.; Zik á nov á , A.; Maixner, J.; Koˇcˇr é , M. Investigation of sorption and transport of sorbate molecules in crystals of MFI structure type by iodine indicator technique Microporous Mesoporous Mater 1998 , 23 , 295–308 [ CrossRef ] 54 Verboekend, D.; Chabaneix, A.M.; Thomas, K.; Gilson, J.-P.; P é rez-Ram í rez, J. Mesoporous ZSM-22 zeolite obtained by desilication: Peculiarities associated with crystal morphology and aluminium distribution CrystEngComm 2011 , 13 , 3408–3416. [ CrossRef ] 55 Sousa, L.V.; Silva, A.O.; Silva, B.J.; Teixeira, C.M.; Arcanjo, A.P.; Frety, R.; Pacheco, J.G. Fast synthesis of ZSM-22 zeolite by the seed-assisted method of crystallization with methanol Microporous Mesoporous Mater 2017 , 254 , 192–200. [ CrossRef ] 56 Munusamy, K.; Das, R.; Ghosh, S.; Kumar, S.K.; Pai, S.; Newalkar, B. Synthesis, characterization and hydroisomerization activity of ZSM-22/23 intergrowth zeolite Microporous Mesoporous Mater 2018 , 266 , 141–148. [ CrossRef ] 57 Song, C.-Y.; Meng, J.-P.; Li, C.; Zeyaodong, P.; Liang, C.-H. Synthesis of ZSM-22/ZSM-23 intergrowth zeolite as the catalyst support for hydroisomerization of n-hexadecane J. Fuel Chem. Technol 2021 , 49 , 712–725. [ CrossRef ] 58 Wong, S.L.; Armenise, S.; Nyakuma, B.B.; Bogush, A.; Towers, S.; Lee, C.H.; Wong, K.Y.; Lee, T.H.; Rebrov, E.; Muñoz, M. Plastic pyrolysis over HZSM-5 zeolite and fluid catalytic cracking catalyst under ultra-fast heating J. Anal. Appl. Pyrolysis 2023 , 169 , 105793. [ CrossRef ] 59 Zhou, N.; Dai, L.; Lv, Y.; Li, H.; Deng, W.; Guo, F.; Chen, P.; Lei, H.; Ruan, R. Catalytic pyrolysis of plastic wastes in a continuous microwave assisted pyrolysis system for fuel production Chem. Eng. J 2021 , 418 , 129412. [ CrossRef ] 60 Panda, A.K.; Singh, R.K. Experimental Optimization of Process for the Thermo-catalytic Degradation of Waste Polypropylene to Liquid Fuel Adv. Energy Eng 2013 , 1 , 74–84 61 Miandad, R.; Barakat, M.; Aburiazaiza, A.S.; Rehan, M.; Ismail, I.; Nizami, A. Effect of plastic waste types on pyrolysis liquid oil Int. Biodeterior. Biodegrad 2017 , 119 , 239–252. [ CrossRef ] 62 Tekin, K.; Akalın, M.K.; Kadı, Ç.; Karagöz, S. Catalytic degradation of waste polypropylene by pyrolysis J. Energy Inst 2012 , 85 , 150–155. [ CrossRef ] Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Other Environmental Sciences Concepts:

[back to top]

Discover the significance of concepts within the article: ‘Obtaining Zeolites from Natural Materials of Volcanic Origin for Application...’. Further sources in the context of Environmental Sciences might help you critically compare this page with similair documents:

Silica, Alkaline solution, Catalytic activity, Transport, Chemical composition, X-ray diffraction, Raw material, Scanning electron microscope, Chemical stability, FTIR Analysis, SEM analysis, FTIR, Thermal stability, Thermal decomposition, Plastic waste, Methanol, Crystalline phase, Chemical resistance, FTIR spectra, Ion Exchange Method, Protonated form, Crystal morphology, Functional group, Amorphous phase, Heterogeneous catalyst, Liquid nitrogen, Wastewater, Specific surface area, Rice Husk Ash, Open access article, Textural properties, Hydrothermal treatment, Zeolite, Experimental optimization, SEM image, Polypropylene, Ball mill, Pore diameter, Volcanic origin, Liquid product, Amorphous material, Gaseous products, Sorption, Fast synthesis, Pyrolysis, Tubular furnace, Conventional route, Aluminosilicate, Catalytic efficiency, Alkene, Cooling system, Sodium silicate, Acidic character, Precursor materials, Pyrolysis products, Thermal pyrolysis, Catalytic pyrolysis, Fuel production, Waste Plastic, Micropore volume, Syngas, BET analysis, Liquid fuel, Catalytic degradation.