Mesoporous Catalysts Research Articles

1,4-Bis(pyridin-1-ium)benzene trifluoroacetate coordinated to chloropropyl functionalized SiO2-nano-NiFe2O4 (BPBTCSF): as a novel and effectual mesoporous bi-functional magnetic catalyst for the synthesis pyrido[2,3-d:6,5-d']dipyrimidines

Here in, we report the synthesis of 1,4-Bis(pyridin-1-ium)benzene trifluoroacetate coordinated to chloropropyl functionalized SiO2-nano-NiFe2O4 (BPBTCSF). Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), elemental mapping analysis, Brunauer-Emmett-Teller (BET), thermal gravimetric analysis (TGA), vibrating-sample magnetometry (VSM) and X-ray diffraction (XRD) techniques characterized the framework of this catalyst. The catalytic activity of this nano-composite was then examined in the one-pot four-component reaction of 2-thiobarbituric acid, NH4OAc, and aldehyde for synthesis of pyrido[2,3-d:6,5-d']dipyrimidines under optimal conditions (5 mg of BPBTCSF, H2O, 25°C). BPBTCSF exhibits benefits as a heterogeneous catalyst, such as exciting performance in the production of derivatives (2 to 5 min, 90% to 98%), six times reproducibility with a slight decrease in catalytic activity, the simultaneous presence of acidic and basic sites (Hydrogen attached to the electronegative nitrogen atom and CF3COOˉ, respectively), convenient purification and separation from the reaction mixture.

Integrated in situ spectroscopic characterization of bi-functional nanoporous hybrid catalysts

Bi-functional catalysts possess various catalytic sites and can catalyze different types of reactions in a single-pot cascade manner. Herein, we report the synthesis and characterization of mono- and bifunctional silica-based mesoporous hybrid catalysts involving acid and base active sites. The ability for cooperative catalysis has been investigated using a multi-technique approach involving powder X-ray diffraction, FT-IR, and multinuclear MAS NMR spectroscopy, as well as thermogravimetric analysis. To elucidate the nature and strength of multifunctional catalytic sites, different types of probe molecules were employed and studied using spectroscopic techniques. The results show that the activity of the mesoporous surface-grafted acid and/or base sites is directly related to the intimacy criterion, the separation between the different types of catalytic sites. The presence or absence of mutual interactions between the different catalytic sites dictates the selectivity and yield of the reactions.

Effect of Hierarchical Architecture of Nickel Modified Mesoporous Catalysts on the Knoevenagel Condensation Reaction

AbstractA series of ordered mesoporous silicas (MCM‐41, SBA‐15 and KIT‐6) were successfully synthesized and modified with nickel by incipient wetness impregnation method. The supports and catalysts were characterized by N2 adsorption‐desorption, XRD, TEM, H2‐TPR, UV vis‐DR, XPS, ICP and Py FT‐IR techniques. All the materials were evaluated in the Knoevenagel condensation reaction between vanillin and malononitrile under microwave irradiation. The catalytic results show the key role that the chosen porous structure plays in the deposition of the active phase and its catalytic behaviour. Thus, by designing a suitable mesoporous catalyst it was possible to carry out such Knoevenagel condensation to obtain 2‐(4‐hydroxy‐3‐methoxybenzylidene) malononitrile through a highly efficient and environmentally friendly process, without solvents and reducing reaction times by employing microwave heating.

Selective Oxidation of p-Cymene over Mesoporous LaCoO3 by Introducing Oxygen Vacancies.

The liquid-phase catalytic oxidation of p-cymene to 4-methylacetophenone is an industrially significant reaction. However, the targeted oxidation of a specific C-H bond of p-cymene is extremely difficult due to there being many branched chains in p-cymene. In here, we designed a simple method to synthesize mesoporous LaCoO3 catalysts with rich oxygen vacancy (Oov) sites. The as-prepared mesoporous LaCoO3 after 550 °C calcination (mLaCoO3) exhibits remarkable catalytic activity for solvent-free oxidation of the p-cymene reaction, with a selectivity of over 80.1% selectivity for 4-methylacetophenone and a conversion of 50.2% for p-cymene (120 °C, 3 MPa). Besides, recycling studies have demonstrated that the mLaCoO3 catalysts can be reused ten times in the aerobic oxidation of the p-cymene reaction without significant catalytic activity reduce. The experimental and characterization results indicated that the mesoporous structure of the catalyst is conducive to the generation of surface Oov, which can properly facilitate ion spread during the catalytic process and afford enough O2 for intermediate species, thus is beneficial for the generation of 4-methylacetophenone. This work demonstrates that the selectivity oxide p-cymene with an O2 employing mLaCoO3 catalyst is highly promising for chemical industrial applications.

Rational Design of Mesoporous ZnFe2O4@g-C3N4 Heterojunctions for Environmental Remediation and Hydrogen Evolution.

Mesoporous catalysts with a high specific surface area, accessible pore structures, and appropriate band edges are desirable for optimal charge transfer across the interfaces, suppress electron-hole recombination, and promote redox reactions at the active sites. The present study demonstrates the rational design of mesoporous ZnFe2O4@g-C3N4 magnetic nanocomposites (MNCs) with different pore sizes and pore volumes following a combination of facile thermal itching and thermal impregnation methods. The MNCs preserve the structural, morphological, and physical attributes of their counterparts while ensuring their effectiveness and superior catalytic capabilities. The morphological analysis confirms the successful grafting and confinement of ZnFe2O4 nanoparticles with the polymeric g-C3N4 nanosheets to form heterojunctions with numerous interfaces. The MNCs possess uniformly distributed small mesopores (pore size <4 nm), ample active sites, and a high specific surface area of 62.50 m2/g. The mesoporous ZnFe2O4@g-C3N4 notably improve hydrogen evolution rate and methylene blue dye degradation. The optimal loading weight of ZnFe2O4 is 20 %, in which the MNCs display the highest hydrogen evolution rate of 1752 μmol g-1 h-1 and photo-Fenton dye degradation rate constants of 0.147 min-1, upon solar-light illumination. Furthermore, the photocatalysts demonstrate recyclability over five consecutive cycles, confirming their stability, while easy separation using a simple magnet underscores practical utility.

Developing highly stable and reusable WO3 on mesoporous cellular foam silica for dilute bioethanol dehydration to ethylene

This study developed a highly stable and reusable WO3 on mesoporous cellular foam silica catalyst (MCF-Si) for dilute bioethanol (70%v/v) dehydration to ethylene. WO3/MCF-Si exhibited exceptional performance during reaction, maintaining a high yield of ethylene ranging from 79.6% to 76.3% even in the final cycle over five consecutive cycles (20 h each), operating without requiring regeneration. Characterization of the spent catalyst revealed the preservation of key textural properties and a shift in the acidity profile. The strength of acidity transitioned from weak to strong acidity, while the type of acid sites evolved from Lewis to Bronsted acid sites. However, the remaining acidity remained sufficiently high to promote efficient ethylene production. Additionally, WO3/MCF-Si demonstrated outstanding resistance to coke formation, with a coke content measured below 0.9 wt%. In light of these findings, WO3/MCF-Si emerges as a promising candidate catalyst for developing sustainable processes for converting dilute ethanol to ethylene.

Hydrothermal Liquefaction of Microalgae to Bio-oil Using Zeolite Catalysts

Mesoporous zeolite silica-alumina catalysts were investigated for their impact on the hydrothermal liquefaction (HTL) to convert Nannochloropsis oculata into bio-oil. The commercial catalysts were characterized using characterization instruments which are XRD, SAP, and TPD-NH3 analysis, revealing distinctive structural and physicochemical properties. The catalytic screening was conducted at varied reaction temperatures (160–240 °C), durations (60–120 min), and catalyst loadings (1–5 wt.%). The result revealed that ZSM-5 demonstrates effectiveness as a catalyst for the HTL of Nannochloropsis oculata, yielding high bio-oil production under optimized conditions. Strong acid sites and high surface area density are highlighted as the key factors contributing to the catalyst's enhanced performance in promoting valuable bio-oil components.

Non-hydrolytic sol-gel synthesis of amine-functionalized silica: Template- and catalyst-free preparation of mesoporous catalysts for CO2 valorization

Carbon dioxide utilization presents an important and topical research topic. However, the performance of catalysts needed for CO2 transformations does not achieve the necessary levels for their widespread application. To this end, we decided to study non-aqueous condensations providing amine-functionalized silica catalysts, possibly active in CO2-epoxide cycloaddition reaction. While non-hydrolytic sol-gel method is well-known for its efficiency in providing highly porous Lewis and Brønsted acid metallosilicates, here we show for the first time its application for the preparation of silica-based catalysts containing basic groups. First, the reaction conditions were screened to reproducibly obtain porous materials with preserved amine moieties. These were identified as follows: silicon tetraacetate and bridging tertiary amine silanes as precursors, toluene as a solvent, and temperature between 160 and 180 °C. In such a way, materials with up to 776 m2 g−1 and 1.58 cm3 g−1 were obtained in one-step process, without any template, after conventional drying step. Next, the amine-functionalized materials were tested in CO2-epoxide coupling providing cyclic organic carbonates with high selectivity (>99 %) and moderate activity (up to 86 % epichlorohydrin conversion after 1 h at 120 °C and 10 bar CO2). The characterization of spent catalysts revealed a presence of cyclic organic carbonates at the catalyst surface as well as conversion of tertiary amine groups to quaternary ammonium moieties.

Synthesis of Self-Assembled Mesoporous ZnO Microspheres Designed for Microwave-Assisted Photocatalytic Degradation of Tetracycline.

Microwave-assisted photocatalysis offers a novel approach for degrading antibiotics, while the mechanism of enhancement of microwave-induced photocatalysis remains poorly understood. In this study, tetracycline (TC) was degraded using the method of microwave-assisted photocatalysis with a ZnO catalyst, which was synthesized by the combination of hydrothermal and calcination methods. The self-assembled mesoporous ZnO catalyst exhibited superior catalytic activity in degrading TC. It is found that the degradation efficiency of TC by the ZnO catalysts with microwave-assisted photocatalysis is 4.27 times higher than that of photocatalysis alone. Of particular significance, we found that the optical absorption range of ZnO increased and the band gap decreased when microwave was introduced into the photocatalytic system. Semi-in situ photochemical tests demonstrated that more photogenerated electron-hole pairs were detected under microwave, thus further improving the photocatalytic activity of ZnO. The separation efficiency and charge transfer efficiency of photogenerated electron-hole pairs also improved due to the increase of oxygen vacancies in the synergistic effect. Meanwhile, h+ and ·OH were the main active species in the degradation system. The mechanism of microwave-induced photocatalysis is illustrated, and an efficient way for degrading antibiotic is provided in this work.

Oxidation of Toluene over the Pt-Embedded Mesoporous CeO2 Hollow Nanospheres with Advanced Catalytic Performances.

In this study, the novel Pt-embedded mesoporous CeO2 hollow nanospheres (Pt-MS-CeO2-H) with varying Pt contents (0.5-3.0 wt %) were facilely prepared. The Pt nanoparticles were one-pot embedded within the mesoporous shell of Pt-MS-CeO2-H and assisted with the reduction Ostwald ripening process. The traditional preparation methods often face challenges, such as the uneven distribution or aggregation of nanoparticles, as well as difficulty in maintaining high catalytic activity at low Pt content. Compared with the traditional supported Pt/MS-CeO2 catalyst, the embedding strategy facilitated precise control over the position, distribution, and uniformity of Pt nanoparticles within the CeO2 mesoporous shell. Additionally, the encapsulation process of Pt nanoparticles played a pivotal role in generating oxygen vacancies and activating surface chemical adsorption of oxygen. Resultantly, the toluene oxidation performances of 1Pt-MS-CeO2-H catalyst showed much lower T90 (171 °C) than 1Pt/MS-CeO2 (311 °C). To elucidate the underlying reasons, in situ diffuse reflectance infrared Fourier transform spectroscopy of toluene oxidation was employed to identify the reaction intermediates and pathways over these catalysts. In summary, the Pt-embedded mesoporous CeO2 hollow nanosphere catalysts were considered as potential candidates when designing high-performance toluene catalytic oxidation catalysts.

Improving H2S remediation efficiency through metal-free biochar modification: Nitrogen introduction and mesopore formation

Hydrogen sulfide (H₂S) poses substantial risks to human safety and infrastructure due to its toxicity and corrosive properties. In this study, we present a novel approach to enhance the selective catalytic oxidation of H₂S by synthesizing a nitrogen-doped mesoporous carbon catalyst (denoted as M/B-X-PZ-T) through pyrolysis at 600–800 °C. Our catalyst, derived from commercial biochar, incorporates melamine as a nitrogen source and employs KCl and ZnCl₂ as porogens via the salt-templating method. The resulting catalyst, M/B-1-PZ-700, exhibits an impressive specific surface area of up to 1269.77 m²/g and a high mesopore ratio, with effective nitrogen doping reaching up to 15.35 at%. Remarkably, M/B-1-PZ-700 demonstrated exceptional performance, achieving 100 % H₂S conversion and 94 % sulfur selectivity at 170 °C, surpassing previous nitrogen-doped carbon catalysts. Furthermore, our optimized catalyst maintained over 95 % H₂S conversion and superior sulfur yield for 36 h, indicating excellent long-term stability. This metal-free catalyst derived from biochar offers a promising, sustainable, and eco-friendly solution for effectively mitigating hazardous H₂S emissions.

Efficient conversion of used palm cooking oil into biogasoline over hydrothermally prepared sulfated mesoporous silica loaded with NiMo catalyst

Fossil-based fuels remain a primary global energy source, but their finite and non-renewable nature raises concerns about long-term sustainability. These issues underscore the urgent need for renewable and eco-friendly alternatives such as converting vegetable oil into biofuel. The present work reported biogasoline production from used palm cooking oil catalyzed by sulfated mesoporous silica impregnated with nickel-molybdenum bimetal using the hydrothermal method for both steps. We evaluated the effect of sulfuric acid concentration and metal loading amount on the acidity of the resulting catalysts. Catalysts' performance was assessed through the catalytic cracking and hydrocracking processes with a catalyst-to-feed ratio of 1% at 550°C and an atmospheric pressure. In comparison to mesoporous silica (MS) and sulfated mesoporous silica (SMS-2), along with an increase in acidity, NiMo-impregnated mesoporous silica (NiMo 1/SMS-2) exhibited superior catalytic performance in biogasoline production in the presence of H2 gas, achieving liquid product conversion and gasoline selectivity of 55.9% and 52.37%, respectively. These results are an excellent step for developing biogasoline in a safer process and confirm the capability of mesoporous silica-based catalysts in biofuel production.

Dielectric Barrier Discharge Plasma Combined with Ce-Ni Mesoporous catalysts for CO2 splitting to CO

Dielectric Barrier Discharge Plasma Combined with Ce-Ni Mesoporous catalysts for CO2 splitting to CO

Ni-Electrocatalytic CO2 Reduction Toward Ethanol.

The electroreduction of CO2 offers a sustainable route to generate synthetic fuels. Cu-based catalysts have been developed to produce value-added C2+ alcohols; however, the limited understanding of complex C-C coupling and reaction pathway hinders the development of efficient CO2-to-C2+ alcohols catalysts. Herein, a Cu-free, highly mesoporous NiO catalyst, derived from the microphase separation of a block copolymer,is reported, which achieves selective CO2 reduction toward ethanol with a Faradaic efficiency of 75.2% at -0.6V versus RHE. The dense mesopores create a favorable local reaction environment with CO2-rich and H2O-deficient interfaces, suppressing hydrogen evolution and maximizing catalytic activity of NiO for CO2 reduction. Importantly, the C1-feeding experiments, in situ spectroscopy, and theoretical calculations consistently show that the direct coupling of *CO2 and *COOH is responsible for C-C bond formation on NiO, and subsequent reduction of *CO2-COOH to ethanol is energetically facile through the *COCOH and *OC2H5 pathway. The unconventional C-C coupling mechanism on NiO, in contrast to the *CO dimerization on Cu, is triggered by strong CO2 adsorption on the polarized Ni2+-O2- sites. The work not only demonstrates a highly selective Cu-free Ni-based alternative for CO2-to-C2+ alcohols transformation but also provides a new perspective on C-C coupling toward C2+ synthesis.

Catalytic Pyrolysis of Polyethylene with Microporous and Mesoporous Materials: Assessing Performance and Mechanistic Understanding.

Testing the performance for the catalytic pyrolysis of plastic waste is hampered by mass transfer limitations induced by a size mismatch between the catalyst's pores and the bulky polymer molecules. To investigate this aspect, the behavior of a series of microporous and mesoporous materials was assessed in the catalytic pyrolysis of polyethylene (PE). More specifically, a mesoporous material, namely sulfated zirconia (Zr(SO4)2) on SBA-15, was synthesized to increase the pore accessibility, which reduces mass transfer limitations and thereby enables to better assess the effect of active site density. To demonstrate this approach, mesoporous SBA-15 wascompared to microporous zeolite Y. Using the degradation temperature during thermogravimetric analysis as a measure of activity, no correlation between acidity and activity was observed for microporous zeolite Y. However, depending on the Mw of PE, the reactivity of the mesoporous catalysts increased with increasing Zr(SO4)2 weight loading, showing that utilizing a mesoporous catalyst can overcome the accessibility limitations at least partially, which was further confirmed by polymer melt infiltration and in situ X-ray diffraction. Product analysis revealed that more aromatics and coke were produced with zeolite Y. The mesoporous material remained active and structurally intact and catalyses PE degradation via acid- and radical-based pathways.

Spatially Confined Alloying of Pt Accelerates Mass Transport for Fuel Cell Oxygen Reduction.

Pt-based alloy with high mass activity and durability is highly desired for proton exchange membrane fuel cells, yet a great challenge remains due to the high mass transport resistance near catalysts with lowering Pt loading. Herein, an extensible approach employing atomic layer deposition to accurately introduce a gas-phase metal precursor into platinum nanoparticles (NPs) pre-filled mesoporous channels is reported, achieved by controlling both the deposition site and quantity. Following the spatially confined alloying treatment, the prepared PtSn alloy catalyst within mesopores demonstrates a small size and homogeneous distribution (2.10 ± 0.53nm). The membrane electrode assembly with mesoporous carbon-supported PtSn alloy catalyst achieves a high initial mass activity of 0.85 A at 0.9V, which is attributed to the smallest local oxygen transport resistance (3.68 S m-1) ever reported. The mass activity of the catalyst only decreases by 11% after 30000 cycles of accelerated durability test, representing superior full-cell durability among the reported Pt-based alloy catalysts. The enhanced activity and durability are attributed to the decreased adsorption energy of oxygen intermediates on Pt surface and the strong electronic interaction between Pt and Sn inhibiting Pt dissolution.

Effect of Acid Properties of Fluorinated Beta and ZSM-5 Zeolites Used as Supports of Ni Catalysts for the Catalytic Hydrodeoxygenation of Guaiacol

Commercial NH4-Beta and Na-ZSM-5 zeolites were fluorinated with different amounts of NH4F and using different procedures (room temperature, conventional refluxing, microwave refluxing). Samples were characterized by XRD, N2 physisorption, FTIR, 1H NMR, SEM-EDS, and TGA of adsorbed cyclohexylamine. An increase in the concentration of NH4F led to fluorinated zeolites with higher surface areas and slightly lower amounts of Brønsted acid sites due to some dealumination. Fluorination by conventional or microwave refluxing at shorter times did not dealuminate ZSM-5, resulting in the formation of higher particle sizes. Ni/fluorinated beta catalysts were more active than Ni/fluorinated ZSM-5 catalysts for the hydrodeoxygenation of guaiacol at 180 °C and 15 bar of H2 for 1 h due to their higher amount of acid sites. The appropriate proportion of metallic and Brønsted acid centers allowed for the selective obtention of cyclohexane (58%) for the Ni supported on beta fluorinated with NH4F 0.1 M catalyst. The combination of this fluorinated beta to a Ni/ordered mesoporous carbon catalyst significantly boosted its selectivity to cyclohexane from 0 to 65%. Fluorinated ZSM-5 samples, although having stronger Brønsted acid sites, as observed by 1H NMR, they had lower amounts, leading to higher selectivity to cyclohexanol when used as catalytic supports.

Comparative study of two mesoporous magnetic and MCM-41 supported Cu complex: High-performance heterogeneous catalysts for aqueous synthesis of tetrazole

The effects of the carrier were studied in the synthesis of tetrazole. Copper catalysts supported on CoFe2O4 and MCM-41 with serine ligands were prepared. Two mesoporous catalysts, CoFe2O4/Ser/Cu and MCM-41/Ser/Cu, (denote Serine with (Ser)) were synthesized and compared the activity of these catalysts in converting nitrile to tetrazole. The prepared material was characterized using powder X-ray diffraction (XRD),field emission scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDS), elemental mapping, vibrating-sample magnetometer (VSM), and nitrogen adsorption–desorption isotherm. The relation between the textural properties of the catalysts and the catalytic performance was investigated. The X-ray diffraction patterns showed the spinel ferrite type for CoFe2O4/Ser/Cu and amorphous SiO2 for MCM-41/Ser/Cu. The distinctive diffraction peaks in the diffraction curves of CoFe2O4/Ser/Cu, and MCM-41/Ser/Cu were identical to those of CoFe2O4, and MCM-41, confirming the preservation of these phases of supports throughout the functionalization processes and formation of -Ser/Cu moiety on the crystalline CoFe2O4 structure and non-crystalline silica structure. FE-SEM images showed the particles in CoFe2O4/Ser/Cu had an average diameter of 20–50 nm and in MCM-41/Ser/Cu had an average diameter of 50–250 nm. The images showed the uniformity and well-ordering of the particles. The slight aggregation in CoFe2O4/Ser/Cu particles implied that their clustering may be the result of modest attraction forces between them. MCM-41/Ser/Cu sample exhibited a type IV isotherm with an H1-type hysteresis loop and diagrams of the CoFe2O4/Ser/Cu showed a type IV isotherm (type H2 hysteresis loop). The MCM-41/Ser/Cu and CoFe2O4/Ser/Cu showed a mesoporous structure and capillary condensation occurred in the nearly cylindrical and ink bottle channels with non-uniform size or shape. The CoFe2O4/Ser/Cu showed surface area by BET and t-plot of 71.17 m2/g and 64.92 m2/g respectively, mean pore size of 14.06 nm, and pore volume of 0.250 cm3/g. The MCM-41/Ser/Cu showed surface area by BET and t-plot of 639.2 m2/g and 484.6 m2/g respectively, with a mean pore size of 5.44 nm, and pore volume of 0.869 cm3/g. The BJH pore size distribution was between 1 and 10 nm for the MCM-41/Ser/Cu and 1–20 nm for the CoFe2O4/Ser/Cu. Two catalysts were used for the synthesis of tetrazole. The CoFe2O4/Ser/Cu shows better activity in the synthesis of 5–substituted 1H-tetrazoles than the MCM-41/Ser/Cu sample despite its lowest surface area (71.17 m2/g). There is no reduction in the conversion of nitrile to tetrazole after the 6 cycles for CoFe2O4/Ser/Cu and after the 4 cycles for MCM-41/Ser/Cu.

Hydrolysis of carbonyl sulfide using non-ionic surfactant-modified mesoporous γ-Al2O3 catalysts with high efficiency

Carbonyl sulfur (COS) was difficult to be removed by conventional desulfurization technologies because of its stable chemical properties. Mesoporous γ-Al2O3 (MA) showed excellent potential for hydrolysis of COS, but the catalyst life was greatly shortened with the progress of the reaction. Therefore, improving the catalyst life is the key to MA which can apply to hydrolysis of COS. In this study, P123 modified mesoporous γ-Al2O3 (P-MA) catalyst was prepared by sol–gel method, and it was regulated by template agent and acidity regulator. These preparation conditions of P-MA were optimized to improve the hydrolysis efficiency of COS. The effects of temperature, space velocity, relative humidity and oxygen concentration for the hydrolysis efficiency of COS were studied. The results show that the optimized P-MA catalyst is suitable for COS low-temperature hydrolysis reaction, and it can maintain 99 % for 10 h under the tough reaction conditions. The only crystal of P-MA was γ-Al2O3 with large specific surface area and uniform distribution pore, which are beneficial to the COS hydrolysis. In addition, the hydrolysis efficiency of COS can also remain 97 % for 10 h in the O2 and CO2 atmosphere, indicating that the P-MA catalyst has a specific anti-poisoning ability. The kinetics and reaction mechanism of COS catalytic hydrolysis were studied, which showed that the adsorption of H2S was the key to hindering the continuous reaction. The P-MA can effectively inhibit the adsorption of H2S, which greatly improved COS hydrolysis life of P-MA. This study provided a theoretical basis for the application of Al2O3 catalyst in the COS hydrolysis.

High coke resistance Ni-based CH4/CO2 reforming catalysts with strong spatial confinement effect: Effect of CeO2 shell thickness

Ni-based catalysts show promise as candidates for the dry reforming of methane (DRM), yet the susceptibility to sintering and carbon deposition is a major obstacle to industrialization. This work demonstrates a mesoporous Ni-based catalyst with a thickness-tailorable CeO2 shell for enhanced spatial confinement effect for the DRM. The Ni-MCM-41@xCeO2 catalysts are prepared at various CeO2 shell thickness through a two-step hydrothermal reaction. The kinetic studies have shown that the Ni-MCM-41@2CeO2 catalyst has the lowest activation energy, producing a high conversion of CH4 and CO2 as high as around 80 % at 700 °C. Our characterizations reveal that the Ni core is tightly confined in the mesoporous skeleton of MCM-41 and within a CeO2 shell. The Ni-MCM-41@2CeO2 catalyst is able to sustain high activity for more than 10 h of operation, with a remarkably reduced carbon deposition (0.28 %) as compared with a conventional Ni-Ce/MCM-41 catalyst (8.77 %). Furthermore, the density functional theory (DFT) calculation supports that the CeO2 shell layer significantly reduces dissociation potential barrier for CH4 and CO2, hence enhancing the catalytic activity of the DRM.