Zeolite Catalysts Research Articles

Comparative Study of Organics Removal from Refinery Wastewater by Photocatalytic Fenton Reaction Coupled with Visible Light and Ultraviolet Irradiation

The study investigates photocatalytic advanced oxidation processes using iron-doped zeolite catalysts in heterogeneous Fenton reactions to degrade organic contents as chemical oxygen demand. The research revealed that the heterogenous photocatalytic Fenton process was the most successful treatment method under acidic circumstances and generated a greater rate of chemical oxygen demand degradation in a concise amount of radiation time. Compared to the heterogenous Fenton process with ultraviolet irradiation, it increased oxidation and was affected by catalyst load, power of hydrogen pH, hydrogen peroxide amounts, and temperature. The findings showed that the iron-doped zeolite catalyst, pH, and temperature significantly degraded the chemical oxygen demand. The experiment determined that the optimal conditions were obtained at a catalyst load of 0.07 g, pH of 3, with 20% excess of hydrogen peroxide, 40 °C in 2 hours for the ultraviolet/ iron-doped zeolite/hydrogen peroxide system that gave 99.84 % of the removal of the chemical oxygen demand. The heterogeneous photocatalytic Fenton method accompanied the reactions by hydroxyl radical production, which quickly reached its maximal reduction.

The Effect of Catalyst Amount and Time on the Results of Converting Rubber Wood Chip Waste by Catalytic Pyrolysis into Alternative Energy

In the rubber plantations of South Sumatra, covering an area of 1,013,969 hectares, there exists an underutilized waste stream known as rubber wood waste. This waste can be subjected to pyrolysis to Yield char, bio-oil, and syngas products. This research is centred on pyrolyzing rubber wood waste, employing various zeolite catalysts and time durations, to explore the potential of alternative energy sources and calculate the Specific Energy Consumption (SEC). The pyrolysis results, with variations in catalysts and time, indicate that the optimal combination is at a temperature of 390°C, using 6% zeolite catalyst, and a duration of 70 minutes. The resultant Yields comprise char at 21.73% with a calorific value of 6264.87 kcal/g, bio-oil at 22.50%, and syngas at 45.28% with a CH4 content of 55.52%. The most SEC-optimal variation is at a temperature of 390°C, using a 6% zeolite catalyst, and 30 minutes, with an SEC value of 3.25 kWh/L.

Oxidative carbonylation of methane into acetic acid: Effect of metal (Zn, Cu, La, and Mg) doping on Rh/ZSM-5 activity

It was shown that the nature and method of the second element-modifier (Zn, Si, La, and Mg) introduction have a significant effect on the acidic properties of the zeolite catalysts and the active component (Rh) localization, which leads to a change in their catalytic properties in the oxidative methane carbonylation into acetic acid. The most active second components were Cu and Zn, introduced by impregnation (acetic acid yield was 919 and 819 μmol·gcat−1, respectively). Using temperature-programmed desorption of NH3, Fourier-transform infrared spectroscopy of pyridine adsorption and X-ray photoelectron spectroscopy it was found that an improvement of catalyst efficiency was associated with an increased acidity and a greater content of Brѳnsted acid sites together with an increase in the proportion of Rh atoms inside microporous channels and/or channel intersection voids, that are active in the acetic acid formation.

Effects of transition metal doping on the properties and catalytic performance of ZSM-5 zeolite catalyst on ethanol-to-hydrocarbons conversion

In this study, the effects of transition metal-doping on the physicochemical properties and catalytic performance of HZSM-5 catalysts for the conversion of ethanol to hydrocarbons are investigated using experimental data and secondary data from the literature. Hydrothermally synthesized novel ZSM-5 catalysts were modified with different concentrations (0.5 and 10 wt%) of transition metals (Co, Fe, Ni). Characterizations, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, particle size distribution, N2 adsorption and NH3 temperature-programmed desorption, revealed the changes in catalyst properties. The introduction of transition metals affected the surface area, particle size and acidity without altering the MFI structures. In particular, a reduction in surface area was observed, ranging from 2.6 to 23 %, corresponding to the different metal loading of 0.5–10 wt% compared to the surface area of the pure catalyst (397.5 m²/g). In addition, metal-doping led to an increase in Lewis acid sites, accompanied by a decrease in strong acid sites. Catalytic evaluation at 350 °C and a space velocity of 12 h−1 showed improved performance in metal-doped ZSM-5 catalysts, which exhibited high selectivity towards fuel-range hydrocarbons, compared to the unmodified catalyst. Catalysts with low metal doping showed optimal catalytic activity, while high metal doping led to increased coke deposition and deactivation of the catalyst due to an increased concentration of strong acids. These results underline the suitability of metal-modified ZSM-5 for hydrocarbon reactions and provide valuable insights for the optimization of catalysts for ethanol conversion to fuel-range hydrocarbons.

Production of low sulphurated diesel-like fuel from waste mineral and tire oils by pyrolytic distillation

In this study is to produce diesel-like fuel (DLF) from waste mineral and waste tire oil which are harmful to the environment and human health, desulfurization process of these fuels, and to compare these DLF according to diesel fuel (DF) standards. In this direction, DLF was produced by pyrolysis method from waste mineral and waste tire oil in a pyrolysis reactor. Depending on the temperature (200-380 °C), it was determined that the liquids obtained from pyrolysis have a high amount of sulfur content. In order to reduce the sulfur, a two-stage desulfurization method was applied. In the first stage, both DLF were treated with 10% perlite, CaO and zeolite catalysts in the basic desulfurization process. Since the sulfur content in diesel-like mineral fuel (DLMF) was within the limits of 0.1% (EN ISO 8754) DF pyrolysis liquid, it was determined that there was no decrease in sulfur content. However, the sulfur content of diesel-like tire fuel (DLTF) was removed by 25.3% with 10% volumetric perlite application. After desulfurization process, the second stage of acidic desulfurization was applied. As a result, using the basic approach reduced the sulfur level in the DLF, but applying an acidic solution increased it.

Synthesis and Determination of Active Acidic/Basic Sites on Zn Loaded Zeolite (ZSM-5) Catalyst & Its Role in Catalytic Reforming of Naphtha Using HPMR Reactor

Synthesis and Determination of Active Acidic/Basic Sites on Zn Loaded Zeolite (ZSM-5) Catalyst & Its Role in Catalytic Reforming of Naphtha Using HPMR Reactor

Transformation of Single‐Use Plastics into Lighter Hydrocarbons via an Economical Coal Fly Ash based Zeolite Catalyst

AbstractA mixture of zeolite X and A, derived from coal fly ash (CFA), was protonated and utilized as an acid catalyst to decompose single‐use plastics (SUP) waste into lighter hydrocarbons. Low‐density polyethylene (LDPE) was selected as the source of SUP, and this study aimed to investigate the catalytic effects of the protonated CFA‐derived zeolite (H‐XA) as an economical option on the LDPE pyrolysis temperature and output. CFA converted into H‐XA through the conventional alkali fusion, followed by sonication and simplified hydrothermal and protonation processes. The impact of the alkali agent ratio on the resulting product was investigated, and outcomes were evaluated. The product with optimum properties was then selected for investigation in the LDPE pyrolysis studies. Finally, the results were compared with commercial Protonated Zeolite Socony Mobil‐5 (H‐ZSM5) and thermal decomposition without catalysts. Regarding LDPE degradation temperature, H‐XA could lower that by 97 °C compared to thermal degradation, which was almost the same as commercial H‐ZSM5 with 110 °C. The pyrograms obtained through the Pyrolysis‐gas chromatography‐mass spectrometry (Py‐GCMS) analysis indicated the elimination of heavier hydrocarbons in the presence of H‐XA and the product spectra laid in the range of C3 to C9, which was entirely different from the LDPE with hydrocarbons of varying lengths. Moreover, kinetic studies on the LDPE decomposition reactions in this work have revealed that LDPE conversion occurs at a lower activation energy level in the presence of H‐XA, which is comparable to the energy level observed when H‐ZSM5 is used as the catalyst. The synthesis of H‐XA with desirable catalytic activity, such as the ability to lower the LDPE degradation temperature and make lighter hydrocarbons as the pyrolysis output, suggests the great potential of the CFA‐based acid catalyst for use in SUP recycling. This represent a game of waste versus waste within the framework of the circular economy, where the environment is the ultimate winner.

Conversion of NOx over Aluminosilicate Cu-CHA Zeolite Catalysts Synthesized Free of Organic Structure-Directing Agents

Cu-CHA zeolites have proven to be effective for NOx reduction, but a drawback in using CHA zeolites is the cost associated with using expensive organic structure-directing agents. To overcome this drawback, we are reporting here the synthesis of Cu-CHA zeolite catalysts in both their NH4-form as well as K-form that do not require the use of organic structure-directing agents. After comprehensive characterization by XRF, XRD, 27Al NMR spectroscopy, FE-SEM, SEM/EDS, N2-adsorption/desorption, NH3-TPD, H2-TPR, and XPS, the zeolite catalysts were tested for NOx conversion by NH3-selective catalytic reduction (NH3-SCR). Cu-NH4-CHA zeolite catalysts exhibited remarkable activity and thermal stability over a wide temperature window, outperforming their counterpart K-forms. Among the NH4-forms of CHA zeolite catalysts, the 0.1 M Cu-NH4-CHA showed the best catalytic performance, achieving 50% NOx conversion at a temperature as low as 192 °C, and reaching full conversion of NOx at 261 °C. These Cu-based CHA zeolite catalysts are promising thanks to their environmentally friendly synthesis and offer the opportunity of maximizing DeNOx strategies in applications for NOx pollution abatement.

Direct Conversion of CO2 into Alcohols Using Cu-Based Zeolite Catalysts.

The direct hydrogenation of CO2 into alcohols is an attractive but challenging catalytic reaction. Herein, it was shown that Cu nanoparticles supported on MFI and BEA zeolites have high catalytic activity and selectivity for converting CO2 into ethanol and isopropanol. Furthermore, we investigated the effect of introducing mesopores via carbon templating and encapsulating the Cu nanoparticles via subsequent recrystallization. All the catalysts were characterized by N2 physisorption, XRD, SEM, TEM, NH3 TPD, XPS, and XRF, before we tested them in a high-pressure water-filled autoclave with a constant partial pressure of CO2 (1 MPa) and an increasing partial pressure of H2 (3-5 MPa). In general, the mesoporous zeolite catalysts resulted in a higher CO2 conversion and selectivity toward ethanol than their non-mesoporous equivalents, while the recrystallized catalyst with encapsulated Cu nanoparticles had a higher selectivity towards isopropanol. For example, Cu@m-S1 showed the highest isopropanol productivity among the recrystallized mesoporous zeolites, corresponding to 20.51 mmol g-1 h-1 under the given reaction conditions. These findings highlight the importance of mesopores in zeolite catalysts for CO2 hydrogenation to alcohols and point a new direction for further research and development.

Greenhouse Gas Conversion into Hydrocarbons and Oxygenates Using Low Temperature Barrier Discharge Plasma Combined with Zeolite Catalysts

Global warming occurs as a result of the build-up of greenhouse gases in the atmosphere, causing an increase in Earth’s average temperature. Two major greenhouse gases (CH4 and CO2) can be simultaneously converted into value-added chemicals and fuels thereby decreasing their negative impact on the climate. In the present work, we used a plasma-catalytic approach for the conversion of methane and carbon dioxide into syngas, hydrocarbons, and oxygenates. For this purpose, CuCe zeolite-containing catalysts were prepared and characterized (low-temperature N2 adsorption, XRF, XRD, CO2-TPD, NH3-TPD, TPR). The process of carbon dioxide methane reforming was conducted in a dielectric barrier discharge under atmospheric pressure and at low temperature (under 120 °C). It was found that under the studied conditions, the major byproducts of CH4 reforming are CO, H2, and C2H6 with the additional formation of methanol and acetone. The application of a ZSM-12 based catalyst was beneficial as the CH4 conversion increased and the total concentration of liquid products was the highest, which is related to the acidic properties of the catalyst.

One-Pot Synthesized Fe-AEI Zeolite Catalysts Contribute to Direct Oxidation of Methane

One-Pot Synthesized Fe-AEI Zeolite Catalysts Contribute to Direct Oxidation of Methane

Enhanced lactide yield in catalytic conversion of L-lactic acid from passivation of external acidic sites on aluminosilicate Beta zeolites by coating siliceous Beta zeolite

The development of efficient Beta zeolite for conversion of L-lactic acid (L-LA) to L,L-lactide (L-LT) is in urgent need but still remains challenging. Herein, we reported an enhancement of the L-LT yield by passivation of external acidic sites on aluminosilicate Beta zeolites by coating pure silica Beta (Al-Beta@Si-Beta). The passivation of external acidic sites was strongly evidenced by in situ 2,4,6-tritertbutylpyridine (TTBP) adsorption FT-IR spectra, where the external acidic sites of Al-Beta@Si-Beta were effectively covered. In the tests for conversion of L-LA to L-LT, the Al-Beta@Si-Beta exhibited much higher L-LT yield than commercial microporous Beta zeolite, which is reasonably attributed to that the passivation of external acidic sites of the Beta zeolite significantly decreases molecular weight of the reaction intermediates, favoring for reduction of coke formation. Furthermore, this strategy is extended to passivate mesoporous Beta zeolite (Al-Beta-meso@Si-Beta). As expected, the Al-Beta-meso@Si-Beta displayed higher L-LT yield than the Al-Beta@Si-Beta because the presence of mesoporosity in the zeolite catalyst is favorable for mass transfer in the conversion of L-LA to L-LT. The strategy for coating pure siliceous zeolite might offer a new opportunity to develop highly efficient zeolite catalysts for the production of L-LT in the future.

Ce-modified USY zeolite catalysts for catalytic oxidation of chlorinated VOCs: Effect of the location of CeO2 and its synergistic effect with USY zeolite

The catalytic behavior of a catalyst for chlorine-containing volatile organic compounds (CVOCs) oxidation largely depends on the synergistic interaction between the oxidizing and acidic sites. In the present work, two catalysts with different distributions of CeO2 on the inner and outer surfaces of 4.0Ce-USY-ex and 4.0Ce-USY-dp (USY zeolite) were prepared respectively by ion exchange and deposition methods, with a purpose of finding out how the location of the oxidation sites (CeO2) influence its synergistic effect with the acidic sites of zeolite. The results show that 4.0Ce-USY-ex is much more active for catalytic degradation of 1,2-dichloroethane (DCE), while 4.0Ce-USY-dp catalyst exhibit higher catalytic degradation activity for other structured CVOCs (dichloromethane (DCM), trichloroethylene (TCE), chlorobenzene (CB)). CeO2 in 4.0Ce-USY-ex catalyst mainly disperses in the pore channels of USY zeolite, and there are many strong acid centers on the surface, which is conducive to the dechlorination conversion of CVOCs. However, CeO2 in 4.0Ce-USY-dp catalyst is mainly distributed on the outer surface of USY and has strong oxidation ability, which contributes to the deep oxidation of CVOCs. Moreover, the presence of a large number of strong acid centers on the catalyst surface of 4.0Ce-USY-ex catalysts leads to severe accumulation of surface carbon species and significantly decreases its stability towards DCE. However, a large number of active oxygen species on the surface of 4.0Ce-USY-dp and CeO2 catalysts are beneficial to the deep oxidation of DCE, reducing the formation of surface carbon and thus improving the stability of the catalyst. Thus, the influence of the location of the oxidation sites on its synergistic effect with the acidic sites was established in the present work, which could provide some new ideas for the rational design of CVOCs degradation catalyst with appropriate distribution of active sites.

Analysis Of Isothermal Pyrolysis Process Of Municipal Waste Into Bio-Oil With The Addition Of Natural Catalyst (Zeolite) In Supporting National Energy Security

Conversion technology will continue to evolve. These developments started from the industrial revolution 1.0 to the industrial revolution 4.0, but in these developments even though technology solves a problem, it has the potential to cause new problems such as environmental problems. Environmental problems that can occur starting from energy conversion that is not environmentally friendly as well as the use of several technologies that cause pollutants that are quite dangerous if high intensity can even cause health problems, acid rain and climate change. The pyrolysis process has been proven capable of converting municipal solid waste (SPP) into bio-oil (BO) where most of the BO produced is hydrocarbon fuel with light oil (naphtha) and diesel types. Many studies have been carried out by various groups, but the raw materials used are single SPP components such as plastic, biomass, tire rubber, paper and not the real SPP. Therefore, this research was conducted to see the effect of using variations in zeolite catalyst concentration on the bio-oil produced. Variations in zeolite catalyst concentration are divided into concentrations of 0.25; 0.5; 0.75 and 1. For the pyrolysis test, it was carried out at a temperature of 400 ° C, with a reaction time of 60 minutes. From the results of experiments that have been carried out, the most ideal concentration for producing the most bio-oil products is at a concentration of 0.5. This indicates that the more catalysts are used in the pyrolysis process, the more syngas products will be produced. So the use of catalysts in the pyrolysis process can increase thermal efficiency and the pyrolysis process can be carried out at low temperatures for the production of bio-oil from mixed waste. If following national oil needs and these reserves continue to be exploited, Indonesia will only have oil reserves for the next 7-8 years or until 2028. Another problem is that the use of conventional fuel oil will produce large amounts of CO2 and will make a major contribution to climate change and global warming.

New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH3

5Cu-USY and Ce-doped 5Cu8Ce-USY zeolite catalysts were prepared by the conventional impregnation method. The obtained catalysts were subjected to the hydrothermal ageing process. The catalytic performance of the selective catalytic reduction of NOx with NH3 (NH3-SCR) was evaluated on both fresh and aged catalysts. Physical/chemical characterizations such as X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS) were performed, along with detailed in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) experiments including CO adsorption, NH3 adsorption, and NO + O2 reactions. Results showed that, for the 5Cu-USY catalyst, hydrothermal ageing treatment could somehow improve the low-temperature SCR activity, but it also led to significant formation of unfavorable byproducts NO2 and N2O. Such an activity change can be attributed to hydrothermal ageing inducing the migration of isolated Cu+ species in the sodalite cavities towards the super cages of the USY zeolites. The increased content of Cu+ species in the super cages was beneficial for the low-temperature activity improvement, but, at the same time, it also facilitated ammonia oxidation at high temperatures. Ce doping after hydrothermal ageing has a “double-edged sword” effect on the catalytic performance. First of all, Ce doping can inhibit Cu species migration by self-occupying the internal cage sites; thus, the catalytic performance of 5Cu8Ce-USY-700H remains stable after ageing. Secondly, Ce doping introduces a CuOx–CeO2 strong interaction, which facilitates lattice oxygen mobility by forming more oxygen vacancies so as to increase the concentration of surface active oxygen. These changes, on the one hand, could help to promote further oxidative decomposition of nitrate/nitrite intermediates and improve the catalytic performance. But, on the other hand, it also causes the byproduct generation to become more severe.

Recent Advances in Metal−Zeolite Catalysts for Direct Propane Dehydrogenation

Recent Advances in Metal−Zeolite Catalysts for Direct Propane Dehydrogenation

From Biomass to Fuel Blendstocks via Catalytic Fast Pyrolysis and Hydrotreating: An Evaluation of Carbon Efficiency and Fuel Properties for Three Pathways.

Biomass was upgraded to fuel blendstocks via catalytic fast pyrolysis (CFP) followed by hydrotreating using three approaches: ex situ CFP with a zeolite catalyst (HZSM-5), ex situ CFP with a hydrodeoxygenation catalyst (Pt/TiO2) and cofed hydrogen, and in situ CFP with a low-cost mixed metal oxide catalyst (red mud). Each approach was evaluated using a common pine feedstock and the same hydrotreating procedure. The oxygen contents in the CFP oils ranged from 17 to 28 wt % on a dry basis, and the carbon efficiencies for the CFP processes were in the range of 28-38%. The residual oxygen was reduced to <1 wt % during hydrotreating, which was operated for 104-140 h for each CFP oil without plugging issues. The hydrotreating carbon efficiencies were 81-93%. The CFP pathway with the hydrodeoxygenation catalyst gave the highest overall carbon efficiency from biomass to fuel blendstocks (34%) but, at the same time, also the highest cumulative hydrogen consumption during CFP and hydrotreating. The zeolite pathway produced the largest fraction boiling in the gasoline range and the highest estimated octane number due to the high aromatic content in that CFP oil. The in situ red mud pathway produced the largest fraction of diesel-range products with the highest derived cetane number. However, advances in the CFP and hydrotreating process are required to improve the fuel blendstock properties for all pathways.

Bio-fuel production from catalytic microwave-assisted pyrolysis of the microalgae Schizochytrium limacinum in a tandem catalytic bed

The formation of oxygenated and nitrogenated compounds during microalgae pyrolysis interferes with bio-oil usage as a viable competitor against fossil fuels. Aiming to reduce these undesirable substances and improve aromatic hydrocarbon production, the catalytic microwave-assisted pyrolysis of the microalgae Schizochytrium limacinum in a tandem catalytic bed was investigated. This study evaluated the effects of the reaction temperature and the tandem catalytic bed (NiHTC/SiC and NiHZSM 5/SiC: hydrotalcite and zeolite catalysts) on the product distribution and bio-oil composition. Experimental results showed that ex-situ catalytic microwave-assisted pyrolysis was able to produce satisfactory liquid yields, reaching 58 % in the optimal test. The results showed that NiHTC/SiC (hydrotalcite) favored de-acidification and de-nitrification reactions, leading to more intermediate compounds, such as ketones and alcohols. These compounds were then converted into hydrocarbons over the acid sites of the NiHZSM-5/SiC (zeolite) catalyst. Maximum hydrocarbon and benzene yields of 95 % and 78 %, respectively, were reached at 500 °C and a NiHTC/SiC:NiHZSM-5/SiC catalyst ratio of 1:1. In addition, the regeneration and recycling of the catalytic bed were successfully performed and did not affect catalytic activity regarding hydrocarbon generation. This study also provided crucial data on improving energy recovery (which ranged from 70 to 94 %) and bio-oil quality during the catalytic pyrolysis of microalgae. The satisfactory results indicated that the biomass energy was successfully stored as a liquid fuel.

Influence of the synthesis method of Cu/Y zeolite catalysts for the gas phase oxidative carbonylation of methanol to dimethyl carbonate

Dimethyl carbonate is an environmentally friendly molecule with increasing applications as reactant, solvent, and fuel additive. Oxidative carbonylation of methanol, with reactants in the gas phase and catalyzed by copper-exchanged Y zeolites, is a promising alternative route for dimethyl carbonate production. This work is focused on the improvement of the catalyst formulation and preparation methods. Catalysts were prepared using two methodologies: solid-state ion exchange and liquid-ethanol ion exchange. Five different copper salts were used as precursors and the NH4+ and Na+ forms of the Y zeolite as supports. The Na+ form of the Y zeolite removed the Brønsted acidity of the support and, therefore, the reaction rate of acid-catalyzed undesired dehydration and decomposition reactions was reduced. The use of copper chloride salts as precursors was crucial to obtain suitable catalysts for dimethyl carbonate formation. Among all the tested catalysts, those prepared using CuCl2 precursor and the Na-Y zeolite by the liquid-ethanol ion exchange method showed the best performance (0.72 molDMC/molCu h). This catalyst exhibited the highest surface chloride content and Lewis acidity.

3D-printed monolithic ZSM-5@nano-ZSM-5: Hierarchical core-shell structured catalysts for enhanced cracking of polyethylene-derived pyrolysis oils

The catalytic upgrading of polyethylene-derived pyrolysis oils using ZSM-5 zeolites enables the cost-effective production of valuable chemicals from plastic waste, fostering a circular economy through resource recycling. To achieve high-performance catalyst design, balancing active site accessibility and selectivity is crucial. Here, we report a monolithic ZSM-5 @nano-ZSM-5 core-shell catalyst (mZ@nZ) fabricated via vat photopolymerization, in situ crystal engineering, and a one-step desilication-recrystallization treatment. The micromorphologies and microstructures of the core-shell catalysts are investigated using electron microscopies and physical adsorption methods. The mZ@nZ catalyst features a self-supporting face-centered cubic macrostructure with a layer of compositionally heterogeneous ZSM-5 zeolites, which comprises a catalytically benign nano-ZSM-5 shell (Si-rich) and a catalytically active ZSM-5 core (Al-rich). Abundant mesopores are created in mZ@nZ through desilication and zeolite agglomeration processes. This design offers three significant advantages: (1) enhanced active site accessibility via in situ zeolite growth, (2) surface passivation using a Si-rich shell to minimize side reactions, and (3) improved diffusion facilitated by the hierarchical structure, reducing light olefin secondary reactions and coke formation. Compared to pristine monolithic ZSM-5 and a reference pelletized catalyst, the mZ@nZ catalyst demonstrates superior performance in terms of higher light olefin yields and selectivities, with enhanced resistance to coking in the model compound and real LDPE pyrolysis oil cracking reactions. This research showcases a rational design approach at both macroscopic and microscopic scales, offering valuable insights for advancing polyolefin waste upgrading and novel zeolite catalyst design.