Type Zeolite Research Articles

Cytotoxicity and Genotoxicity Effects of a Magnetic Zeolite Composite in Daphnia magna (Straus, 1820).

Zeolite type 5A combined with the magnetic properties of maghemite nanoparticles facilitate the rapid absorption of heavy metals, which makes them an interesting proposal for the remediation of water contaminated with lead and arsenic. However, the physicochemical analysis related to concentration and size for the use of this magnetic zeolite composite (MZ0) in water bodies and the possible toxicological effects on aquatic fauna has not yet been carried out. The main objective of the research work is to determine lethal concentrations that cause damage to Daphnia magna based on LC50 tests, morphology, reproductive rate, and quantification of the expression of three genes closely involved in the morphological development of vital structures (Glass, NinaE, Pph13). To achieve this objective, populations of neonates and young individuals were used, and results showed that the LC50 for neonates was 11,314 mg L-1, while for young individuals, it was 0.0310 mg L-1. Damage to morphological development was evidenced by a decrease in eye size in neonates, an increase in eye size in young individuals, variations in the size of the caudal spine for both age groups, and slight increases in the heart size, body, and antenna for both age groups. The reproductive rate of neonates was not affected by the lower concentrations of MZ0, while in young individuals, the reproductive rate decreased by more than 50% from the minimum exposure concentration of MZ0. And for both ages, Glass gene expression levels decreased as the MZ0 concentration increased. Also, the MZ0 evidenced its affinity for the exoskeleton of D. magna, which was observed using both light microscopy and electron microscopy. It is concluded that MZ0 did not generate significant damage in the mortality, morphology, reproductive rate, or gene expression in D. magna at lower concentrations, demonstrating the importance of evaluating the possible impacts on different life stages of the cladoceran.

Immobilization of 137Cs in NaY type zeolite matrices using various heat treatment methods

The accumulation of liquid radioactive waste presents a significant global challenge, necessitating effective strategies for safe management. This study investigates the immobilization of 137Cs radionuclides, a prominent component of liquid radioactive waste, in ceramic matrices based on 137Cs-saturated NaY Faujasite zeolite. Various thermal methods were employed, including cold pressing and sintering, cold pressing and sintering with microwave assistance, hot pressing, and spark plasma sintering, to enhance immobilization capabilities. Zeolite powder was saturated with 137Cs radionuclides using an adsorption technique with low-activity model liquid radioactive waste. In-situ XRD and dilatometry methods were used to study the thermal behavior during NaY Faujasite annealing. The influence of calcination temperature on lattice parameters and crystallite size was assessed. Immobilization effectiveness was evaluated through relative density, Vickers microhardness, compressive strength, and metal ion leaching kinetics. Mechanistic evaluation was performed using XRD and SEM-EDX studies. Results showed that spark plasma sintering exhibited the highest efficiency for immobilizing 137Cs radionuclides in NaY Faujasite matrices. This research contributes to liquid radioactive waste management by providing insights into the thermal behavior and enhanced immobilization capabilities of ceramic matrices.

Analysis of nitrogen adsorption capability at various activation temperatures of Klaten natural zeolite

The Pressure Swing Adsorption (PSA) method operates by passing air through an adsorbent to produce concentrated oxygen gas. Zeolites are commonly utilized as adsorbents due to their ability to adsorb nitrogen from the surrounding air. Two types of zeolites commonly employed are natural and synthetic zeolites. While the utilization of natural zeolites as adsorbents in oxygen purification remains limited, their potential as an alternative adsorbent is worth exploring in this field. This study focused on developing physically activated Klaten natural zeolite as an adsorbent to enhance oxygen purity. Physical activation involved heating for 1.5 hours using an electric oven at four temperature variations (250ºC, 300ºC, 350ºC, and 400ºC). Additionally, four distinct flow rates were tested: 0.1; 0.5; 1.0; and 1.5 lpm. Oxygen purification testing revealed that higher activation temperatures led to greater increases in oxygen concentration. The highest increase of 2.45% was achieved at an activation temperature of 400ºC, while the lowest increase of 1.75% was observed at 250ºC with a flow rate of 0.1 lpm. With a 10-minute holding period, oxygen content during the adsorption process ranged from 1.35% to 2.45%, compared to 0.60%-0.75% without holding. Physical activation of zeolite from Klaten enhanced its nitrogen absorption capacity, indicating the potential of natural zeolite from Klaten for oxygen purification through optimized activation processes, possibly via chemical activation

ZIF-8 metal organic framework, carboxymethylcellulose and polyvinyl alcohol bio-nanocomposite controlled-release phosphorus fertilizer: Improved P management and tomato growth

This study is concerned with the synthesis, characterization, and application of bio-nanocomposite films using a mixture of carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA) integrated with zeolitic imidazolate type 8 (ZIF-8) nanoparticles (NPs). The advanced bio-nanocomposites were employed as a coating for triple superphosphate (TSP) fertilizers, and their impact on tomato plant growth was evaluated. The successful integration of ZIF-8 into the composite matrix was determined by distinct changes in Fourier transform infrared (FTIR) spectra, indicating significant structural modifications. Morphological analyses by scanning electron microscopy (SEM) revealed alterations in the surface characteristics of the CMC/PVA films. Furthermore, energy dispersive X-ray (EDX) analysis confirmed the elemental composition of the resulting nanocomposite. The precision-coated TSP fertilizers exhibited a notable enhancement in mechanical strength, as evidenced by their superior resistance to crushing. The coated TSP also exhibited a controlled release of phosphorus over time, prolonging the release of phosphorus for up to 9 days in water and 50 days in soil. In soil, the 0.5 % ZIF-8 NP coating delayed the release of phosphorus, with only 12.29 ± 2.75 % released after five days compared to 96.96 ± 2.03 % for uncoated TSP. The application of coated TSP fertilizers to tomato plants (of the MARIA variety) resulted in a 13.79 % increase in leaf number and a 15.83 % increase in plant height compared to uncoated TSP. This research underscores the pivotal role of advanced coating fertilizers in fostering sustainable and efficient agricultural practices, thereby making a substantial contribution to the advancement of innovative agrochemical solutions.

Regulating cerium location in Y zeolite and its influence on adsorptive desulfurization for thiophene in benzene

CeY zeolite sorbent was reported to have a high adsorptive desulfurization selectivity for thiophene. However, only the cerium in the supercage, which is larger than the thiophene molecule, is effective for thiophene adsorption. In this case, regulating the cerium location to anchor it more in the surpercage of Y zeolite is an important issue. Herein, the glycine was used as a complexing agent with cerium to control its size, ensuring that the cerium precursor is in the supercage. G0.1CeY were prepared by ion exchange technique with glycine and cerium coordination from NaY. The adsorption capacity of sorbents was measured, and their physical and chemical properties were characterized by XRD, SEM, N2 adsorption/desorption, NH3-TPD, and in situ FT − IR. The glycine complexation could effectively control the location of Ce, so that the G0.1CeY has the highest content of Ce located in the supercage. Moreover, in order to further explore the influence of zeolite type, HY was used as the raw material to prepared G0.1CeHY in the same way. G0.1CeHY has a higher desulfurization performance than that of G0.1CeY, whereas the Ce content in its supercage is lower. The NH3-TPD and Py-FT − IR results that the medium-strong Brønsted acid of the G0.1CeHY sorbent is also effectively for the improvement of desulfurization efficiency. The G0.1CeHY exhibits the hightest desulfurization effectiveness (51 %) and the highest breakthrough adsorption capacity of 5.42 mg/g.

Tuning the Hydrothermal Synthesis of FAU-type and ANA-type Zeolites Derived from the Philippine Bentonite

The synthesis of zeolites from local resources has been an attractive route to address the demand for more economical means in the production of zeolites for commercial applications. In particular, Philippine bentonite – a local clay material –has been used as a raw ingredient to synthesize zeolites, faujasite-type (FAU), and analcime-type (ANA) via hydrothermal synthesis. The silicon-aluminum ratio (SAR) and crystallization temperature were varied to investigate the conditions in the synthesis of pure FAU and ANA-type zeolites. X-ray diffraction allowed the identification of zeolite phases upon comparison to reference patterns from the International Zeolite Association database. The sample with the highest degree of crystallinity of 98% (ANA-type) was prepared at a temperature of 150 °C and an initial SAR of 1.18. This sample also exhibited the largest particle size of 29.1 μm in diameter. Scanning electron micrographs showed octahedral, spherical, and cross morphologies of the products, with average particle size ranging from 1.24 (± 0.13) to 29.1 (± 1.66) μm. The transformation of Philippine bentonite to different types of zeolites demonstrates the viability of local clays as raw resource material for hydrothermal synthesis of a wide range of zeolite frameworks.

Effect of the Nature, the Content and the Preparation Method of Zeolite‐Polymer Mixtures on the Pyrolysis of Linear Low‐Density Polyethylene

The effect of the preparation method of the mixture catalyst/polymer on the linear low‐density polyethylene (LLDPE) pyrolysis is studied by comparing the results obtained when the polymer and the catalyst (Hβ or HZSM‐5) are extruded or simply mixed in powder form. By improving the polymer/catalyst contact through extrusion, the polymer degradation took place at lower temperature. The effect of extrusion is more pronounced with Hβ compared to HZSM‐5 owing to the highest external surface of Hβ. While the yields of gas/liquid/coke do not differ with the preparation method when HZSM‐5 is used as catalyst, more significant amount of liquid phase and high production of paraffins are observed when Hβ/LLDPE mixture is extruded, according to random scission pathway reactions. The subsequent reactions are limited by the size of the pore, which impede hydrogenation reactions, producing high molecular weight molecules. Regardless of zeolite type, the micropores of the zeolite are more affected by deactivation by coke when extrusion method is used, this effect being much more important for HZSM‐5. This result is a consequence of a polymer pre‐degradation during the extrusion process in which the first cracks of the polymer at low temperature and the first pore blockages can be generated.

Mechanical properties of low calcium alkali activated binder system under ambient curing conditions

These days, the construction industry is facing sustainability issues, leading to the selection of greener, low-carbon, alkali-activated materials. This study examines a low calcium alkali activated system composed of three constituents (ceramic brick, metakaolin waste, and phosphogypsum). The AAB compositions consist of the primary precursor, waste ceramic brick, which is increasingly (20–100 wt%) replaced with waste metakaolin. The alkaline solution was made of sodium hydroxide and water; dosage depended on the Na2O/Al2O3 ratio (1.00–1.36). The AAB specimens were inspected by using XRD (X-ray diffraction) and FT-IR (Fourier transform infrared spectroscopy) methods for the evaluation of mineral composition, accompanied by SEM–EDS (scanning electron microscopy & energy dispersive X-ray spectroscopy) for the analysis of the microstructure. The compressive strength after 7, 28 and 90 days, along with water absorption and softening coefficient were determined. Also, mixture calorimetry was established. The results have shown that the initial materials are suitable for producing medium-strength alkali-activated binder under ambient temperature. The maximum compressive strength was reached by using the combination of 80% CBW and 20% MKW (13.9 and 21.2 MPa after 28 and 90 days respectively). The compressive strength development was linked with the formation N–A–S–H gel and faujasite type zeolite. A higher level of geopolymerization in composition with metakaolin waste led to lower compressive strength. Consequently, binding materials with low demand of high final and especially early compressive strength could be produced under ambient temperature curing, making them more sustainable.

Structural Characterisation of Zeolites Derived from Lithium Extraction: Insights into Channel- and Cage-Type Frameworks

This study investigates the structural and adsorption characteristics of channel- and cage-type zeolites obtained through lithium extraction. Through XRD, FT-IR spectroscopy, and adsorption isotherm analyses, distinct adsorption behaviours of CH4 and CO2 were observed in both zeolite types. Cage-type zeolites exhibited higher adsorption capacities attributed to their structural advantages, highlighting the importance of structural framework selection in determining adsorbent efficacy. The presence of structural defects and an amorphous phase influenced adsorption behaviours, while thermodynamic data underscored the role of adsorbate properties. Kinetics studies revealed the influence of the structural framework on CH4 adsorption and CO2 adsorption kinetics. Analysis of adsorbate–adsorbent interactions demonstrated robust interactions, particularly with LPM16-Y. These findings offer insights into the potential applications of zeolites in gas adsorption processes, emphasising the importance of structural properties and adsorbate characteristics in determining adsorption performance.

Kinetic Relationships of the Adsorption of Lysozyme and Bovine Serum Albumin onto Zeolites of BEA and MFI Structural Types

Kinetic Relationships of the Adsorption of Lysozyme and Bovine Serum Albumin onto Zeolites of BEA and MFI Structural Types

Embryonic zeolite-directed synthesis of ZSM-34 and SSZ-13 zeolites

The use of an organic structure-directing agent (OSDA) makes zeolite synthesis expensive and environmentally non-friendly. Seeded zeolite synthesis offers an environmentally benign alternative that avoids using an OSDA while providing a high purity, crystallinity, and yield in the product. In this study, we report using embryonic zeolites (EZs) as efficient seeds to obtain industrially important zeolites such as ZSM-34 and SSZ-13 in an OSDA-free synthesis system. Our results showed that zeolites ZSM-34, SSZ-13 and LTL could be obtained depending on the Al/Si ratio in the synthesis system. The synthesis time was considerably shorter than other ZSM-34 and SSZ-13 syntheses methods reported in the literature, achieving more than 90% crystallinity. The physicochemical analysis showed that highly crystalline zeolites with characteristics similar to the OSDA synthesized counterparts were obtained. Furthermore, the EZs seeding approach is facile, low cost, and environmentally friendly, provided the synthesis is OSDA-free. In addition, the EZs seeds can be obtained under hydrothermal synthesis conditions. The method can be potentially applied to the synthesis of other zeolite types.

An optimal combination of Na+ and H+ co-ions for high-performance Cu-impregnated *BEA zeolites: Unravelling the trade-off between the cold-start hydrocarbon trap activity and hydrothermal stability

A Cu-impregnated *BEA (denoted as BEA) type zeolite can serve as an effective hydrocarbon (HC) trap, but its long-term hydrothermal stability should be improved for real uses. However, designing robust high-performance HC traps, which is closely related to the confined environment that accommodates active Cu species and strengthens the zeolite structure, remains elusive. In this study, to the best of our knowledge, we, for the first time, systematically varied the Na content in the BEA zeolite prior to Cu impregnation. Intriguingly, we found a trade-off between the cold-start test (CST) activity (a simplified trap test for simulated HC emissions) and hydrothermal stability of the Cu-impregnated BEA zeolites. Specifically, increasing Na content decreased the CST performance monotonically, whereas it increased the hydrothermal stability. The decreased CST performance could be attributed to the less formation of the active Cu species (both Cu cations inside for preferred HC adsorption and CuO particles outside for facile HC oxidation). In addition, the improved hydrothermal stability benefited from dual features: Na+ ions could alleviate the zeolite structural collapse/damage during hydrothermal treatment (HT) at 800 °C by reducing the amount of most easily hydrolyzed Si-O(H)-Al bonds and avoid the formation of large CuO particles, which are known to destroy the zeolite structure during HT. As a net, we revealed that the Cu-impregnated BEA zeolite with an optimal Na/Al ratio of ca. 0.7 was key to achieving marked CST efficiencies in the HT state (22 %) in contrast to the H-form-based counterpart that exhibited extremely poor performance (i.e., nil).

WITHDRAWN: An Investigation of a Hybrid Solar-Mineral Disinfection Technique Using Zeolite and Dead Sea Clay

Effluents from water treatment plants (WTP) can often contain a complex mixture of residual micro-contaminants and organisms, not removed during wastewater treatment. A combined trickling filter, activated sludge treatment, ozonation, membrane filtration, and suspended biofilm reactors have been shown to reduce these contaminants in waste effluent but at high capita cost. This study examined an inexpensive method of purifying water, which combines solar water disinfection with natural mineral clays (SOMIN-DIS). The study involved the addition of two types of mineral clays, Zeolite and Dead Sea minerals, to containers of polluted wastewater, at varying concentrations. The containers were then subjected to different durations of sunlight exposure. Then, samples were taken from all of the containers to quantify the overall numbers of Total Coliform, Pseudomonas aeruginosa (P.aeruginosa), and Escherichia coli (E.coli), utilizing the IDEXX system. The findings indicated that incorporating Dead Sea clay and Zeolite into SODIS-treated wastewater decreased the overall number of harmful microorganisms and shortened the disinfection duration, as compared to using natural minerals and solar water disinfection (SODIS) independently. Additionally, the study determined that the most effective concentration of Dead Sea minerals, resulting in the least amounts of harmful microorganisms and shortest purification duration, was 0.001g/ml. In contrast, the optimum concentration of Zeolite was 0.002g/ml. In general, the addition of Dead Sea and Zeolite minerals to the wastewater increased the inactivation of bacteria under SODIS from 40% to 65%.

Cooperative and Bifunctional Adsorbent-Catalyst Materials for In-situ VOCs Capture-Conversion.

Volatile organic compounds (VOCs) are gases that are emitted into the air from products or processes and are major components of air pollution that significantly deteriorate air quality and seriously affect human health. Different types of metals, metal oxides, mixed-metal oxides, polymers, activated carbons, zeolites, metal-organic frameworks (MOFs) and mixed-matrixed materials have been developed and used as adsorbent or catalyst for diversified VOCs detection, removal, and destruction. In this comprehensive review, we first discuss the general classification of VOCs removal materials and processes and outline the historical development of bifunctional and cooperative adsorbent-catalyst materials for the removal of VOCs from air. Subsequently, particular attention is devoted to design of strategies for cooperative adsorbent-catalyst materials, along with detailed discussions on the latest advances on these bifunctional materials, reaction mechanisms, long-term stability, and regeneration for VOCs removal processes. Finally, challenges and future opportunities for the environmental implementation of these bifunctional materials are identified and outlined with the intent of providing insightful guidance on the design and fabrication of more efficient materials and systems for VOCs removal in the future.

Effect of zeolites on the reduction of the ecotoxicity of carbamazepine in the environment

In this study, the impact of calcination of zeolites on the ecotoxicity of carbamazepine solutions in two matrices, water and synthetic sewage, was assessed. Two types of zeolites were tested: natural zeolite, in the form of a zeolite rock consisting mainly of clinoptilolite, and a synthetic zeolite type 5 A. Additionally, zeolites were calcined at a temperature of 200 °C. The kinetics of carbamazepine adsorption in aqueous solutions and in synthetic sewage matrix was determined. Higher adsorption capacity was obtained for carbamazepine aqueous solutions as well as zeolites after the calcination process. Considering type of zeolite, the highest and fastest uptake of carbamazepine was observed for natural zeolite after calcination. In the case of ecotoxicity, carbamazepine solutions before adsorption was the most toxic towards Raphidocelis subcapitata, next Aliivibrio fischeri and Daphnia magna, regardless to the matrix type. The differentiation in toxicity regarding the type of matrix was observed, in the case of algae and bacteria, higher toxicity was demonstrated by carbamazepine solutions in the water matrix, while in the case of crustaceans—the sewage matrix. After the adsorption process, the toxicity of carbamazepine solutions on zeolites decreased by 34.5–60.9 % for R. subcapitata, 33–39 % for A. fischeri and 55–60 % for D. magna, thus confirming the effectiveness of the proposed method of carbamazepine immobilization.

Effects of Cu species in Cu-SSZ-13 zeolites on the performance of NOx reduction reactions

In diesel vehicle exhaust after-treatment systems, high silica Cu-SSZ-13 has received increasing attention as a commercialized catalyst owing to its high efficiency in selective catalytic reduction reactions with NH3 (NH3-SCR). However, research on the regulation of Cu2+ species within metal active centers in the pore structure of chabazite (CHA)-type zeolite to improve catalytic performance lacks sufficient depth. Herein, SSZ-13 zeolite with various Al distributions was prepared by adjusting the proportion of N,N,N-Trimethyl-1-adamantanaminiumhydroxide (TMAdaOH) and Na in the initial gel. Moreover, three representative Cu-SSZ-13 catalysts with different Cu2+ species were synthesized via an ion exchange method. 23Na MAS NMR and NO adsorption infrared spectroscopy results revealed that with increasing Na content and decreasing TMAdaOH concentration in the initial gel, the number of paired Al in the CHA framework gradually increased. Consequently, this increased the number of Cu2+-2Z sites near six-membered ring (MR) and reduced the amount of [Cu(OH)]+-Z sites near eight-MR. The fresh Cu-SSZ-13 catalyst, with a moderate amount of Cu2+-2Z and [Cu(OH)]+-Z, exhibited optimal catalytic performance across the entire temperature window. After hydrothermal aging, Cu-SSZ-13 with a higher concentration of Cu2+-2Z species featured optimal performance among all Cu-SSZ-13 catalysts above 400 °C. These findings indicated the significance of balancing the amount of both Cu2+-2Z and [Cu(OH)]+-Z in the Cu-SSZ-13 zeolite. Additionally, the results elucidated the reaction intermediates involved in the NH3-SCR process catalyzed by Cu-SSZ-13 with various Cu species.

Kinetic analysis of monomolecular cracking of normal Alkanes (C4[sbnd]C6) over Brønsted Acid site of Zeolitic type catalyst with energetic evaluation of transition states using Quantum-Chemical modeling

The work aims to determine the kinetic parameters of reactions for production of light olefins via catalytic cracking reactions of C4–C6 n-alkanes based on the energy characteristics of the transition state using quantum chemical calculations. Cracking reactions of C4–C6 n-alkanes proceed via protolytic mechanism on the Brønsted acid sites of zeolite-containing catalysts. For kinetic studies in this work, the thermochemical parameters of the intermediate stages, including hydrocarbon adsorption and transition state were determined, then the activation energies and rate constants were determined over the temperature range of catalytic cracking process from 773 to 903 K (500–630 °C).The results showed that DFT method in combination with B3LYP and ωB97X-D functionals, and 3–21 G basis demonstrated quite high accuracy in determining thermochemical parameters, including enthalpy, entropy and Gibbs free energy at both energetic levels of adsorption and transition state. Then, modeling continued by calculations of activation energies and rate constants of reactions. Obtained kinetic parameters made it possible to determine the reactivity of hydrocarbons with different chain length. It was obtained that the rate constants of butane cracking reactions with the formation of ethylene are 54–90 times higher than the formation of propylene. The rate constants of pentane cracking reactions with the formation of butylene are on average 5 times higher than the formation of propylene. The rate constants for hexane cracking reactions with the formation of butylene are 2.9–3.7 times higher compared to the formation of propylene.

Interzeolite Transformation from FAU-to-EDI Type of Zeolite.

This study reports for the first time the transformation of the pre-made FAU type of zeolite to the EDI type of zeolite. The concentration of the KOH solution controls this interzeolite transformation, which unusually occurs at both room temperature and under hydrothermal conditions. The transformation involves the amorphization and partial dissolution of the parent FAU phase, followed by the crystallization of EDI zeolite. At room temperature, the transformation (11-35 days) provides access to well-shaped nano-sized crystals and hollow hierarchical particles while the hydrothermal synthesis results in faster crystallization (6-27 h). These findings reveal an example of an interzeolite transformation to a potassium zeolite that lacks common composite building units with the parent zeolite phase. Finally, this work also demonstrates the first room-temperature synthesis of EDI zeolite from a gel precursor.

Low energy synthesis of crystalline mesoporous aluminosilicate consisting of Na-P1 zeolite derived from coal fly ash

Worldwide every year massive amount of coal fly ash is being generated as by product in the power plants which creates economic, environmental and most importantly health problems. Usually coal fly ash is used in cement production worldwide. At present, in Bangladesh, about 95 % of fly ash remains still unutilized. The alkali activation of fly ash has become a top research topic as it is possible to synthesize low cost and ecologically sound mesoporous zeolite type materials. In the present work, to the best of our knowledge, for the first time in Bangladesh, synthesis and characterization of crystalline mesoporous (H3 type hysteresis) aluminosilicate consisting of Na-P1 zeolite with a high BET specific surface area and a high pore volume from coal fly ash based on hydrothermal alkali activation technique have been successfully done. This product has versatile applications like catalysis, gas separation, water softening, water purification, gas sensing etc. The variable of alkali concentration was studied which has the notable influence on the development of the framework of the pores. The untreated coal fly ash (CFA) and the synthesized modified fly ashes (MFAs) were tested by WDS-XRF, XRD, N2 physisorption, FE-SEM, FT-IR, XPS, EDAX-mapping, particle size analysis and other technologies. The BET specific surface area, total pore volume and average pore diameter of the CFA were only 3 m2/g, 0.01 cc/g and 6.3 nm respectively based on nitrogen gas physisorption technique, whereas, after alkali activation at a specific temperature and time, and then curing, significant and promising increased values of the said parameters of 45 m2/g, 0.11 cc/g and 9.8 nm were obtained respectively. In methylene blue dye adsorption experiment, MFA showed higher adsorption capacity (23.87 mg/g).

The Role of Zeolite (Microporous Crystalline Aluminosilicates) In Catalytic Pyrolysis of Waste High- and Low-Density Polyethylene Bags for Production of Fuel and Chemicals: A Review

This review provides a state-of-the-art summary of the role which zeolite plays as a catalyst via pyrolysis as a way of recovering fuels and chemicals from waste high and or low density polyethylene bags. It also highlighted the two types of zeolite (natural or synthetic) which are used as a two-stage pyrolysis−catalysis in giving a free waxing product to pure fuel and chemicals which can be subjected to further analyzing and or upgrading. As yield of oil/wax decreased with the addition of a zeolite as catalyst from 44 and 51 wt.%, (depending on the waste high density polyethylene “HDPE” or low density polyethylene bags “LDPE” and other factors). However, the composition of the pyrolysis−catalysis oils significantly increased in aromatic hydrocarbon content accordingly. In addition, the composition of the oils shifted from high molecular weight hydrocarbons (C16+) to fuel range hydrocarbons (C5−C15), with a high content of single-ring aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylenes, and styrene. This process shows great potential for production of fuels or chemicals, and also addresses the urgent issue of waste HDPE and or LDPE disposal.