ZSM-5 Catalysts Research Articles

Pyrolysis-catalysis of waste tire to enhance the aromatics selectivity via metal-modified ZSM-5 catalysts

Excessive untreated waste tires (WT) have posed threats to the environment and human health. Pyrolysis-catalysis, as a promising treatment technology, could convert WT into high-valued products such as pyrolysis oil. Moreover, BTX compounds (Benzene, toluene, and xylene) were important raw materials in the chemical industry. In order to sharply increase the BTX selectivity in the pyrolytic oil, transition metals (Ni and Fe) were impregnated on the ZSM-5 catalyst. Furthermore, this paper also explored the effect of catalysis modes, catalysts-to-feedstock mass ratios, and catalysis temperatures on the distribution of the aromatics in the WT pyrolysis-catalysis oil. The results suggested that the optimal operating parameters for BTX compound production with a selectivity of 39.87% were in-situ mode, catalysis temperature=600 °C, and catalyst-to-feedstock mass ratio=1:1 by applying Ni/ZSM-5. According to the GC-MS identification results, it proposed that the Diels-Alder reaction of isoprene and cracking and recombination of limonene in the aliphatic hydrocarbon pool were the main paths to generate the aromatics, while the addition of ethylene radicals in the monocyclic aromatic hydrocarbon (MAH) and polycyclic aromatic hydrocarbon (PAH) pools was dominant in the growth of the aromatics. The study provided a viable approach for upgrading WT to produce high-value aromatic products.

Optimization of plastic waste pyrolysis using carbon-metal oxide hybrid nanocomposite catalyst: Yield enhancement and energy resource potential

In this study, plastic waste was efficiently converted into valuable energy resources using a unique pyrolysis technique. A carbon-metal oxide hybrid nanocomposite was introduced as a catalyst, and analyses of structural and surface morphology were conducted. Pyrolysis process parameters such as temperature (PTemp), process time (PTime), and catalyst concentration (CC) were optimized through response surface methodology for a higher yield of energy resources. Char underwent proximate and ultimate analyses, oil underwent physicochemical and Fourier transform infrared analyses, and syngas composition was determined. Optimal conditions were found: PTemp 300 °C, PTime 60 min, CC 1 % for char; PTemp 465 °C, PTime 150 min, CC 1 % for oil; PTemp 550 °C, PTime 60 min, CC 4 % for syngas. Compared to the ZSM-5 catalyst, char, oil, and syngas yields increased by 7.9 %, 10.8 %, and 7.2 %, respectively, at optimum conditions. These findings suggest that waste plastic pyrolysis can effectively meet energy demands with enhanced energy outputs.

The effect of natural waste filter on dimethyl ether production from low calorific coal gasification

In Indonesia, rapid population growth has increased energy demand, especially in the transportation and power generation sectors. The Indonesian government has been active in promoting the use of renewable energy, but the transition from fossil energy is still faced with various challenges, including limited technology and adequate infrastructure. Apart from that, Indonesia's large potential in coal is the main factor slowing down this energy transition. One promising alternative is to convert coal into Dimethyl Ether (DME) through the gasification process, which is a thermochemical process for converting solid fuel into gas, producing syngas containing H2, CO, and CH4. Synthesis purification is essential to produce high-purity DME. This process involves the use of filter materials such as zeolite and rice husk charcoal to remove contaminants such as sulfur. Zeolite, with its chemical absorption properties and regular pore structure, is effective in absorbing H2S from syngas. Meanwhile, rice husk charcoal, which is an agricultural waste rich in silica and has a porous structure, has shown potential as an absorbent material to reduce H2S content in gas. In research on the use of various filter material compositions in the up-draft type coal gasification process with CuO–ZnO–Al2O3 and ZSM-5 catalysts, it was found that a 3:7 ratio for zeolite and rice husk charcoal provided optimal performance. This ratio not only increases CH4 and CO levels in syngas, but is also effective in reducing H2S content. The research results showed that the highest DME production reached 90.10% at a ratio of 3:7, while at a ratio of 2:8 and 5:5, production was 81.61% and 73.64% respectively. These findings emphasize the importance of using diverse filter materials in improving syngas quality and DME synthesis efficiency, strengthening steps to accelerate the energy transition towards more sustainable solutions in Indonesia.

Optimization of catalyst service cycle and start-up considering the reactor-distillation-HEN integration and climate

Considering the catalyst deactivation and seasonal temperature variation, a systematic method is proposed for clarifying the dynamic variation of system operating parameters and targeting the optimal catalyst regeneration cycle and start-up date. Relationships between catalyst activity, reactor inlet and outlet temperatures, reactor heat load, and running time are deduced, as well as that between column temperatures, pressures, energy demands, processing capacity, and production month. Diagrams are constructed to illustrate the parameter variations. With the energy consumption and processing capacity combined, an evaluation index is introduced for integrating the reactor-separator-heat exchanger network (HEN) and optimizing the production start-up date. The proposed method is intuitive and efficient and can be used for system design, guiding production, or fault diagnosis. A benzene alkylation process is studied; the optimal regeneration cycle of the ZSM-5 catalyst is 11 months, and the best start-up date is August, saving 2.32 × 105 kgce (kg standard coal) per production cycle.

Effect of method of preparation of Ni and/or Cu supported on ZSM-5 catalysts for the aqueous phase hydrogenation of levulinic acid to γ-valerolactone

A series of Cu and Ni supported on ZSM-5 catalysts were synthesized by ion exchange (IE) and impregnation (IMP) techniques and examined for the aqueous phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) at atmospheric pressure. Hydrogenation of LA to GVL proceeds through LA dehydration to AL (angelica lactone) and subsequent hydrogenation of it to GVL, emphasizing the combined role of an acid and a metal site present on the catalyst surface. The interaction of Cu and/or Ni with ZSM-5 was elucidated using various characterization techniques such as powder XRD, XPS, H2-TPR, NH3-TPD, CO and/or H2 pulse chemisorption and SS NMR techniques. The CO chemisorption results indicated a lower uptake on Cu-ZSM-5(IMP) than on Cu-ZSM-5(IE). The H2 uptake was lower on Ni-ZSM-5(IE) than on Ni-ZSM-5(IMP). In the comparative analysis, the Ni-ZSM-5(IMP) catalyst exhibited a high rate of GVL formation, while the Cu-ZSM-5(IE) catalyst displayed a larger proportion of AL formation than the other catalysts prepared under similar protocols. The influence of the surface active sites on the product distribution was rationalized based on the physico-chemical characteristics of the fresh and reduced catalysts.

Catalytic pyrolysis of fish waste oil using ZSM-5 catalyst for the production of renewable biofuel

This present study enlightens the eco-friendly green synthesis of ZSM-5 from natural clay montmorillonite, and its proper incorporation with ‘Ni’. Nickle (Ni) was wet impregnated onto HZSM-5 and the resulting catalyst was characterized by various techniques including XRD, BET, N2 Sorption Studies, TPD, SEM and TEM techniques. The SEM images revealed the uniform distribution of Ni over HZSM-5 zeolite catalyst and the XRD results indicated the undistorted crystalline structure of HZSM-5 even after impregnation of Ni. The latter part of the work concentrates on the strength of the catalyst in cracking oil derived from discarded fish parts. Discarded fish waste was pyrolyzed to obtain the fish oil, which was then used for cracking studies. The fish oil was efficiently converted (99% conversion) by Ni/ZSM5 (50 wt %) and yielded 70% liquid fractions, which formed gasoline (78.6%), kerosene (12.3%) and diesel (9.1%). The research is a complete parcel to examine the working potential of the produced biofuel in pre-existing engines. The quality of gasoline fraction was tested according to ASTM standards, which showed that the heating value was slightly lower compared to fossil gasoline. The torque and brake fuel consumption were also examined and it indicated that the fish oil derived gasoline fuel may need to be mixed with the commercial gasoline to optimize its performance.

Catalytic biodiesel production from Jatropha curcas oil: A comparative analysis of microchannel, fixed bed, and microwave reactor systems with recycled ZSM-5 catalyst

In this study, we studied the conversion of Jatropha curcas oil to biodiesel by using three distinct reactor systems: microchannel, fixed bed, and microwave reactors. ZSM-5 was used as the catalyst for this conversion and was thoroughly characterized. X-ray diffraction was used to identify the crystalline structure, Brunauer–Emmett–Teller analysis to determine surface area, and temperature-programmed desorption to evaluate thermal stability and acidic properties. These characterizations provided crucial insights into the catalyst's structural integrity and performance under reaction conditions. The microchannel reactor exhibited superior biodiesel yield compared to the fixed bed and microwave reactors, and achieved peak efficiency at 60 °C, delivering high FAEE yield (99.7%) and conversion rates (99.92%). Ethanol catalyst volume at 1% was optimal, while varying flow rates exhibited trade-offs, emphasizing the need for nuanced control. Comparative studies against microwave and fixed-bed reactors consistently favored the microchannel reactor, emphasizing its remarkable FAME percentages, high conversion rates, and adaptability to diverse operating conditions. The zig-zag configuration enhances its efficiency, making it the optimal choice for biodiesel production and showcasing promising prospects for advancing sustainable biofuel synthesis technologies.

Conversion of C8 aromatics over a dual-bed catalyst.

A dual-bed catalyst was prepared for the conversion of C8 aromatics. The upper bed layer consisted of ZSM-5 covered with SiO2, primarily utilized for ethylbenzene dealkylation. By employing tetraethyl orthosilicate (TEOS) as a deposition agent through the chemical liquid deposition (CLD) method, the modified ZSM-5 catalyst exhibited optimal catalytic performance at a TEOS addition of 0.6 g per gram of catalyst. The lower bed layer contained ZSM-39 catalyst, mainly employed for xylene isomerization reaction. ZSM-39 was synthesized using pyrrolidine as the template, and the best catalytic performance was achieved when the OH-/SiO2 molar ratio in the synthesis system was 0.05. The mass ratio between the upper and lower agents was maintained at 1 : 1. Compared to traditional single-bed ZSM-5 catalysts, the dual-bed catalyst demonstrated enhanced activity and selectivity.

Metal-assisted low-temperature cracking of n-hexane over Rh-encapsulated ZSM-5 catalysts

Naphtha cracking is the most common process for producing light olefins such as ethylene, propylene, and butene. This process consumes enormous amounts of energy, so decreasing the energy consumption and operating temperature is an urgent issue. To decrease the reaction temperature for naphtha cracking, we focused on the metal-assisted cracking reaction, in which paraffin is first dehydrogenated into the corresponding olefin on a metal catalyst, and the produced olefin is then decomposed into light olefins. To effectively realize metal-assisted cracking, we considered metal-encapsulated zeolite catalysts to be useful. In metal-encapsulated zeolite catalysts, the dehydrogenation reaction proceeds inside the zeolite particles, and the dehydrogenated intermediates can access the solid-acid sites frequently. In this study, Rh nanoparticle encapsulated ZSM-5 catalysts (Rh@ZSM-5) were employed for the metal-assisted cracking of n-hexane. Rh@ZSM-5 exhibited significantly high activity for n-hexane cracking below 450 °C owing to the metal encapsulation structure and close proximity between the metal and solid-acid sites. Furthermore, the effects of reaction conditions, reaction temperature, amounts of metal and solid-acid sites, and contact time on metal-assisted n-hexane cracking over the Rh@ZSM-5 catalysts were investigated. The highest light-olefin yield of 38.6 carbon mol% was achieved by the conversion of n-hexane over Rh@ZSM-5 using 0.3 wt% Rh loading, an Si/Al ratio of 100, temperature of 450 °C, reaction time of 0.5 h, and W/F of 2 h.

Micelles Cascade Assembly to Tandem Porous Catalyst for Waste Plastics Upcycling.

Catalytic upcycling of polyolefins into high-value chemicals represents the direction in end-of-life plastics valorization, but poses great challenges. Here, we report the synthesis of a tandem porous catalyst via a micelle cascade assembly strategy for selectively catalytic cracking of polyethylene into olefins at a low temperature. A hierarchically porous silica layer from mesopore to macropore is constructed on the surface of microporous ZSM-5 nanosheets through cascade assembly of dynamic micelles. The outer macropore arrays can adsorb bulky polyolefins quickly by the capillary and hydrophobic effects, enhancing the diffusion and access to active sites. The middle mesopores present a nanoconfinement space, pre-cracking polyolefins into intermediates by weak acid sites, which then transport into zeolites micropores for further cracking by strong Brønsted acid sites. The hierarchically porous and acidic structures, mimicking biomimetic protease catalytic clefts, ideally match the tandem cracking steps of polyolefins, thus suppressing coke formation and facilitating product escape. As a result, light hydrocarbons (C1-C7) are produced with a yield of 443 mmol gZSM-5 -1, where 74.3 % of them are C3-C6 olefins, much superior to ZSM-5 and porous silica catalysts. This tandem porous catalyst exemplifies a superstructure design of catalytic cracking catalysts for industrial and economical upcycling of plastic wastes.

Solid-conversion synthesis of three-dimensionally ordered mesoporous ZSM-5 catalysts for the methanol-to-propylene reaction

Solid-conversion synthesis of three-dimensionally ordered mesoporous ZSM-5 catalysts for the methanol-to-propylene reaction

Product regulation and kinetics for fast pyrolysis of corncob over niobium oxide modified zeolite

Catalytic fast pyrolysis is considered as a promising technology for converting biomass into biofuels. In the present research, a series of NbOx modified ZSM-5 catalysts were developed and applied for the selective fast pyrolysis of corncob into aromatics. Depolymerization and hydrodeoxygenation of lignin constituents as well as the aromatization of polysaccharide fractions were the major source of aromatics. The introduction of niobium oxide into ZSM-5 remarkably enriched the Lewis acids and improved the porous structures. The presence of synergistic effect between acid sites and porous structure of NbOx modified ZSM-5 contributed to the aromatics formation in a certain degree. Under the catalysis of 3Nb/ZSM-5, the optimum aromatic content was 86.4 % at 450 °C with a heating rate of 104 °C/s. In the meantime, 3Nb/ZSM-5 presented good stability and recyclability in the fast pyrolysis of corncob, and over 75 % aromatics was achieved even after 3 cycles. Kinetical study revealed that the Ea value for corncob pyrolysis could be lowered to ∼ 250 kJ/mol with conversion rate range of 0.4–0.7.

Site-Specific Activity Maps Observed during Methanol-to-Olefin Conversion over ZSM-5 Catalysts

Site-Specific Activity Maps Observed during Methanol-to-Olefin Conversion over ZSM-5 Catalysts

Characterization and mechanism elucidation of high-quality bio-oil production from co-pyrolysis of waste low-rank coal fines and de-oiled microalgae biomass using bimetallic (Cu-Cr) ZSM-5 catalyst

The present study provides a cleaner co-pyrolysis strategy for high-quality bio-oil production by utilizing low-cost residues such as low-rank coal (CL), de-oiled microalgae (ALG), and their blends (CLALG). The heavy metal-loaded Cu-Cr-ZSM-5 catalyst is synthesized by using ion-exchange method and investigated in the CL, ALG and CLALG pyrolysis bio-oil upgradation at different catalyst feed ratios (0.5:1, 1:1, 2:1). The synthesized catalyst was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and brunauer-emmett-teller (BET) analysis. The synthesized catalyst is nano-crystalline of average size 7 nm. The microstructure of the synthesized catalyst shows stacked nanorods packing with connected intercrystal and intracrystal mesopores. The catalytic and non-catalytic pyrolysis of CL, ALG and CLALG are performed at 600 °C, 10 °C/min for 60 min. The non-catalytic ALG pyrolysis has shown maximum bio-oil yield (35.7%). The synergistic effect of nanorod morphology, active acid sites and excess mesoporosity of catalyst facilitates efficient deoxygenation, denitrogenation and aromatization of pyrolysis bio-oil with oxygen content from 2.1⎼3.1%, nitrogen content 3.5⎼5.1% and aromatic content 49.4⎼54.4% at catalyst feed ratio of 1:1. The maximum obtained higher heating value (HHV) of bio-oil from catalytic pyrolysis of CL (40.1 MJ/kg) followed by CLALG (38.6 MJ/kg) and ALG (36.5 MJ/kg) is very close to diesel oil with HHV (42⎼46 MJ/kg). Further, a co-pyrolysis mechanism is proposed to systematically investigate possible catalytic action sites to yield high-quality bio-oil. Thus, outcomes of the present study enrich information regarding catalyst development, catalyst feed interaction, and thermocatalytic cracking as emerging efforts towards industrial-scale upgradation of bio-oil to engine fuels.

Designing alkali-exchanged ZSM-5 catalysts for the dehydration of lactic acid to acrylic acid

This report shows that complete control of the degree of alkali exchange is possible by controlling the pH strength, and that is possible to distinguish the selectivity of the cations themselves in the lactic acid (LA) dehydration reaction by excluding undesired active sites arising from excess salts. We discovered that strong base conditions induced by alkali hydroxides (e.g., KOH) increase the degree of alkali ion exchange, and that in the absence of additional salts−such as halogen anions, oxides−the KOH-ZSM-5 catalyst exhibited high acrylic acid (AA) selectivity (∼70%) and durability (100 h). Characterization via temperature-programmed desorption (TPD) and pyridine-infrared (Py-IR) analysis revealed a full exchange of the protons bound to the Si–O–Al sites with potassium in commercial ZSM-5. In addition, structural pore expansion due to the desilication by KOH leads to significant enhancement in the selectivity for AA. The mechanistic impact of KOH treatment on lactic acid dehydration is also systematically verified by in situ IR spectroscopy.

A Study of ZSM-5 Molecular Sieve Shaping for an Innovative Cyclohexene Hydration Process

The development of the zeolite molecular sieves (ZSM-5) molding technique is essential for the cyclohexene hydration reaction distillation process in both industrial and research settings. The reactive distillation process can solve many of the drawbacks associated with the existing technique of manufacturing cyclohexanol via cyclohexene hydration, such as high catalyst digestibility, low conversion rate, and operational challenges. This study developed a series of molded ZSM-5 catalysts with various binder types and contents were constructed. The suggested pseudo-boehmite and hydroxypropyl methylcellulose were chosen as binders for extrusion molding of ZSM-5. The effects of binders on the strength reliability were investigated by strength tests and statistical analysis of the Weibull function. The effects of binders on the physical structure, acidity, and catalytic performance of ZSM-5 were investigated by X-ray diffraction, scanning electron microscopy, physical adsorption of N2, and desorption of NH3. The findings demonstrate that the addition of binder has no effect on ZSM-5's crystal structure. The experiment's results showed that the molded catalyst could be used for the hydration process with over 95% selectivity and a yield of 10.45% cyclohexanol. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Boosted Bio-Jet production: Unveiling the potential of a one-stage concurrent process of deoxygenation/upgrading versus two-stage sequential processes using Pt/Cl-Al2O3@Ni/ZSM-5 catalysts

Bio-jet fuel production from renewable bioresources is an increasingly attractive approach for mitigating the environmental impacts of aviation. Among the different methods available for deriving bio-jet fuel from fatty acids, catalytic hydroprocessing has emerged as a promising and commercially viable technique. Recent studies have focused on identifying suitable catalysts to produce kerosene-type bio-jet fuel, which can serve as blend stocks for aviation fuel after further cracking and isomerization. In this study, a bi-layer catalyst Pt/Cl-Al2O3@Ni/ZSM-5 catalyst was prepared and characterized using various techniques (including XRD, TEM, NH3–TPD, FTIR, H2–TPR, XPS, surface area, and pore size measurements). The thus-prepared catalyst is tested for bio-jet fuel production from Palm kernel oil (PKO). A novel one-stage process yields a high iso-alkane content with a low freezing point of –57 °C. The proposed Pt/Cl-Al2O3@Ni/ZSM-5 bi-layer catalysts in a one-stage process provided satisfactory results, with a conversion rate of 96%. The primary component of the resulting bio-jet fuel was alkanes in the C8-C16 range, with an isomers/normal-alkane (I/N) ratio of 2 and a proportion of 75.6 wt%. Interestingly, the produced bio-jet fuel using the one-stage strategy has significant potential for use as a blend stock to enhance the properties of traditional jet fuels (Jet A and Jet A-1, JP-5, and JP-8).

Effect of Na+ migration and the component proximity on direct conversion of aromatics into aromatics over Fe-based zeolite bifunctional catalysts

Direct conversion of syngas into aromatics (STA) via Fischer-Tropsch (F-T) synthesis, using Fe-based zeolite bifunctional catalysts, has recently become a topic of great interest. The catalytic performance of the Fe-based zeolite bifunctional catalyst is influenced by the component proximity in the STA reaction, in addition to their physicochemical properties. However, the mechanism by which the component proximity affects the STA performance is still unclear. Herein, we investigate the effect of Na+ migration and the component proximity on the F-T reactivity, the aromatic distribution, and catalyst stability in a Fe-based ZSM-5 catalyst system. The correlation between the proximity of two components, the migration of alkali-metal promoters, the evolution of the Fe-based active phase, and the coke on the zeolite is analyzed using XRD, XPS, FT-IR, TG, Mössbauer spectroscopy techniques. The findings indicate that when the components are closer to each other, it encourages the formation of iron carbides and inhibits the coke deposition on the zeolite. However, the migration of alkali metals and the acidic environment of zeolite can decrease the catalyst’s stability and F-T reactivity. Moreover, by improving the hydrophobic nature of the zeolite, we can prevent the transfer of alkali-metal promoters from the Fe-based component to zeolite. This enhances the stability of Fe-based ZSM-5 catalysts in the STA reaction, suggesting a new approach to improve their STA performance.

Maximized energy recovery by catalytic co-pyrolysis of dewatered sewage sludge and polystyrene to contribute in bio-circular economy: Synergistic compositional analysis of bio-oil and syngas through artificial neural networking

Sewage sludge and polystyrene are considered very challenging for the waste management authorities in urban centers across the globe. In the current study, catalytic co-pyrolysis of the dewatered sludge (DS) and waste polystyrene (PS) was conducted. The co-pyrolysis of DS and PS; 60% polystyrene+40% dewatered sludge was concluded as optimum ratio with 11.21% higher energy production as compared with other compositions. The produced bio-oil were investigated having higher slags/wax and lower aromatics. Therefore, ZSM-5 (3% weight basis) catalyst was employed, and it had enriched the bio-oil quality, provided higher aromatic hydrocarbon yields with reduced wax and slag formation. To understand the thermodynamic behavior of all dewatered sewage sludge and polystyrene, detailed TGA analysis was carried out. The relative abundance of the aromatic hydrocarbons was identified by GC-MS and FTIR analysis. The synergist compositional analysis of the bio-oil and syngas was carried out by using artificial neural networking techniques. The aromatic components in bio-oil were found to have positive correlations when catalyst were employed. The proposed energy recovery model had capacity of generating 20,863 KWh/d of electrical energy, dealing 10 tons/d of biowaste: and leads the societies towards cleaner environment and positive contribution to bio-circular economy.

Influence of retention time and catalyst concentrations on catalytic pyrolysis yields of polyethylene and polystyrene

ABSTRACT The present work focuses on enhancing the liquid fraction yields having hydrocarbons in the diesel fuel range from pyrolysis of PS/PE (1:1 wt.%) under the influence of ZSM–5 catalysts in an autoclave reactor. The pyrolysis product yields and their compositions were investigated for varied catalyst concentrations (0%, 5%, 7.5%, and 10%), reaction temperatures (250–500°C), and retention times (20–60 min). The physical and chemical characterization of the feedstocks, catalysts, and thermally and catalytically derived oils were carried out along with elemental analysis of the liquid products. It was observed that 7.5% catalyst concentration exhibited the maximum liquid fraction yields (71.2 wt.%) at 350°C and a retention time of 30 min. Catalytic cracking with a retention time of 20–30 min produced maximum liquid yields with aromatic, aliphatic, and isomerized hydrocarbon contents of 42.9%, 30.15%, and 14.3%, respectively. Expedite weakening of the catalytic activity of the ZSM-5 catalyst was observed with process retention time higher than 30 min. The calorific values of catalytically derived oils were found to be in the range of 44.2–44.8 MJ/kg, and their carbon numbers were between C11 and C19. Thus, these characteristics make these oils a potential candidate to be used as an alternative to diesel fuel. Further, the higher proportions of aromatics and aliphatic compounds present in catalytically derived oils compared to that obtained from thermal pyrolysis affirmed its superiority as a potential diesel substitute.