Shell Catalysts Research Articles

Spontaneous Corrosion Induced Scalable Fabrication of Bayberry‐Like Ni@Ni3S2 Core–Shell Catalysts for 5‐Hydroxymethylfurfural Oxidation

Spontaneous Corrosion Induced Scalable Fabrication of Bayberry‐Like Ni@Ni₃S₂ Core–Shell Catalysts for 5‐Hydroxymethylfurfural Oxidation

Direct Synthesis of H2O2 over AuCu@AuPd Core–Shell Catalysts with Highly Dispersed Pd Sites

Direct Synthesis of H₂O₂ over AuCu@AuPd Core–Shell Catalysts with Highly Dispersed Pd Sites

Polydopamine and NaCl template approach to develop a microporous RuO2@IrOx Core–Shell catalyst for an efficient oxygen evolution reaction in polymer electrolyte membrane water electrolyzers

To obtain a stable and active catalyst for the oxygen evolution reaction (OER) in polymer electrolyte membrane water electrolysis (PEMWE), a microporous RuO2@IrOx core–shell was synthesized using a polydopamine (PDA) coating and a NaCl filler method. A durable IrOx shell was homogeneously formed on the surface of the RuO2 core via impregnation of the PDA coating, which improved the catalytic stability. The NaCl filler created micropores within the nanostructures, increasing the number of active catalytic sites. The strong interaction between the RuO2 core and protective IrOx shell, along with the micropores, significantly improved OER activity, showing an overpotential of 182 mV at 10 mA cm−2. Furthermore, a PEMWE exhibited excellent performance, achieving a current density of 1 A cm−2 at a cell voltage of 1.57 V. These findings provide valuable insights into the potential of RuO2@IrOx as a robust and efficient catalyst for green hydrogen production.

Fabrication of core–shell Fe3O4@SiO2/graphite catalyst to improve the charge separation for enhanced photocatalytic toluene oxidation

Magnetite (Fe3O4) has been regarded as a potential photocatalyst for VOCs degradation. Nevertheless, the magnetism of Fe3O4 always leads to the aggregation of particles, which is adverse for gaseous VOCs degradation. Meanwhile, the fast charge recombination of Fe3O4 seriously limits the photocatalytic activity. Herein, a layer of SiO2 was coated on the surface of Fe3O4, and Fe3O4@SiO2 particles were combined with graphite to prepare the core–shell catalyst for photocatalytic toluene oxidation. Fe3O4@SiO2/G catalyst showed the toluene degradation efficiency of 85.09%, which was 3.2 and 1.3 times than those of Fe3O4 and Fe3O4/G. The coating of SiO2 prevented the aggregation of Fe3O4 and greatly enhanced the specific surface area. Experimental and theoretical calculation proved that the existence of SiO2 promoted the spatial charge separation and inhibited the charge recombination, resulting in the generation of abundant reactive oxygen species. These findings offered an insight into the catalyst design for photocatalytic VOCs oxidation.

Highly Efficient Ni@SiO2 Core–Shell Catalysts for Dry Reforming of Methane Prepared by One-Pot Microemulsion Nucleation and Coating Method

Highly Efficient Ni@SiO₂ Core–Shell Catalysts for Dry Reforming of Methane Prepared by One-Pot Microemulsion Nucleation and Coating Method

Electrochemical Oxidation of Ethanol and Methanol at Rh@Pt Catalysts at 80 °C in Proton Exchange Membrane (PEM) Cells

Efficient oxidation of ethanol to carbon dioxide is crucial for the development of sustainable electrochemical generation of power and hydrogen from bioethanol. However, high anode overpotentials and partial oxidation to acetaldehyde and acetic acid result in low efficiencies and waste management issues. Bimetallic Rh-Pt catalysts have shown enhanced activities and CO2 production in aqueous electrolytes, but not in proton exchange membrane (PEM) cells. In this work Rh@Pt core–shell catalysts, prepared from commercial carbon-supported Rh, have been evaluated in both aqueous H2SO4 and PEM cells. Cyclic voltammetry of aqueous methanol and ethanol has shown that the catalytic activity of the Pt shell is increased by the compressive strain induced by the Rh core, and that there is also a significant bifunctional effect at low Pt coverages. In PEM cells, these effects also increase selectivity for cleavage of the C–C bond of ethanol to produce CO2, which will enhance the efficiencies of ethanol fuel and electrolysis cells for producing power and hydrogen, respectively. Deposition of 0.5 monolayers of Pt onto the Rh core produced the highest CO2 yields at the lowest anode overpotentials, while higher coverages of Pt increased performances and CO2 yields at higher potentials.

Enhanced coke resistant Ni/SiO2@SiO2 core–shell nanostructured catalysts for dry reforming of methane: Effect of metal-support interaction and SiO2 shell

Suppressing coke formation on nickel-based catalysts used in methane-dry reforming is one of the most important issues. We investigate the effect of nickel metal-support interaction and outer porous silica shells on the coke formation in methane dry reforming over Ni/SiO2@SiO2 core–shell catalysts. Using a simple ammonia evaporation method, the Ni/SiO2_AE catalyst, which has highly dispersed nickel nanoparticles with ca. 7 nm, was synthesized and coated with an outer porous silica shell to produce a Ni/SiO2_AE/SiO2 core shell catalyst. Based on the TEM and N2 isotherm results, a 20 nm thick SiO2 shell having pores with a size of about 2 nm was uniformly coated on the Ni/SiO2_AE catalyst. H2-TPR, and XPS analysis results suggest that the Ni/SiO2_AE and Ni/SiO2_AE@SiO2 catalysts have high nickel dispersion. This high dispersion is due to strong metal-support interactions and the formation of Ni phyllosilicate species. On the other hand, the ones synthesized by wet impregnation method have low nickel dispersion due to weaker metal-support interactions. The Ni/SiO2_AE@SiO2 core–shell catalyst showed stable catalytic activity under methane dry reforming conditions at 600 °C. On the other hand, the Ni/SiO2_WI and Ni/SiO2_AE catalysts showed rapid deactivation due to severe coke formation. It can be concluded that the strong metal-support interaction and the silica shell can suppress catalyst deactivation caused by coke formation very effectively.

Insights into the role of Mo in boosting CHx* oxidation for CO2 methane reforming

CHx* oxidation is one of the most vital routes to alleviate the carbon deposition problem of CO2 reforming of methane (DRM) reaction. Whereas, little experimental evidence has been observed on NiMo catalysts where the CHx* oxidation was dominant over its dissociation reaction. Herein, to experimentally unveil the CHx* oxidation route of NiMo catalysts, we design three catalysts with different particle sizes and structures. Among them, Mo/Niphy@SiO2 core shell catalyst demonstrated the dominant CHx* oxidation route over its dissociation based on in-situ diffuse reflectance infrared Fourier transform spectroscopy experiments. This was attributed to the confinement effect of SiO2 and the formation of Ni–Mo alloy, inhibiting the CHx* dissociation reaction. It exhibited relatively stable CH4 and CO2 conversions (77 % and 75 % respectively) within 180 h. By contrast, on Mo/Niphy catalyst which has a big Ni size, CHx* was mainly dissociated to C* and oxidized to CO which further underwent a disproportion reaction to produce CO2 and C*, leading to the severe carbon deposition and unstable DRM performance. The strategy to unveil the dominant role of CHx* oxidation via design catalysts with different sizes and structures sheds light on the study of reaction mechanism of other reactions.

Identifying the Active Site and Structure–Activity Relationship in Hydrodeoxygenation of Ester to Alcohols over an Al2O3@CuZn Core–Shell Catalyst

Identifying the Active Site and Structure–Activity Relationship in Hydrodeoxygenation of Ester to Alcohols over an Al₂O₃@CuZn Core–Shell Catalyst

Transesterification of Castor Oil for Biodiesel Production Using H2SO4 Wet Impregnated Snail, Egg and Crab Shell Catalyst.

Transesterification of Castor Oil for Biodiesel Production Using H2SO4 Wet Impregnated Snail, Egg and Crab Shell Catalyst.

Carbon nitride coupled two-dimensional metal–organic framework core–shell catalyst for photo-enzymatic synergistic degradation of bisphenol A

Carbon nitride coupled two-dimensional metal–organic framework core–shell catalyst for photo-enzymatic synergistic degradation of bisphenol A

Core–Shell catalyst particles for tandem catalysis: An experimental/numerical approach towards optimal design

Tandem catalysis is a promising approach to intensify chemical processes and increase their efficiency. On the other hand, the design of efficient, optimal and targeted tailored tandem catalysts is yet so challenging as the optimal catalyst loading is difficult to assess a priori. In this article, we present a concise route towards the design of optimal core–shell tandem catalyst particles on the example of coupled RWGS and FTS reactions for any specific spherical morphology. The route features five consecutive steps including: tandem system identification, catalyst synthesis, i.e. mono- and tandem-functional, catalyst characterization and initial performance test, kinetic modeling with parameter estimation if necessary, and optimal design of catalysts. The initial step features thermodynamic equilibrium calculations for RWGS and FTS showing a common operational window. Then, Pt and Co are selected as active metals and the formulation of the tandem catalyst is designed. For the second step, the synthesis route for the tandem catalyst Pt,CeO2@SiO2-Co, and the mono-functional catalysts, Pt@SiO2 and CeO2@SiO2-Co are presented. For the third step, all catalysts were tested for CO2 hydrogenation as an exemplary tandem process. A reduced transport model from literature was adjusted for RWGS and FTS reactions with kinetic expression from literature to enable numerical optimization. The kinetic parameters are estimated based on the performance tests of the mono-functional reference materials, i.e. Pt@SiO2 for RWGS and CeO2@SiO2-Co for FTS. The model is validated by cross comparison to the data from the tandem reaction setup. In the fifth step, the model was used for the numerical optimization of the catalyst loading on core and shell leading to the identification of the optimal design, resulting in a significant increase of C2+ Yield.

Unraveling the function of monolayer shell structure over Pt-based alloy catalysts in tuning ethane dehydrogenation reactivity and coking resistance

Ethane direct dehydrogenation (EDH) operated at high temperature easily leads to coke formation. The new core–shell catalysts with monolayer shell exhibited better catalytic performance, and the function of monolayer shell structure is of great importance. This work fully investigated catalytic performance of EDH over six types of core–shell Pt3M@Pt and Pt@Pt3M (M = Fe, Co, and Ni) catalysts with Pt3M and Pt monolayer shell under the experimental conditions. Here, density functional theory (DFT) calculations with kinetic Monte Carlo (kMC) simulations were employed. The results show that the metal M over Pt3M@Pt surface decreases coordination number of Pt-Pt and restricts deep dehydrogenation reactions. The Pt3M@Pt catalysts with d-band center close to Fermi level exhibit higher C2H4(g) formation activity than Pt@Pt3M catalysts at 873.15 K. H2(g) co-feeding significantly decreases the coverage of coking C*+CC* species. The screened Pt3Ni@Pt catalyst presents the highest C2H4(g) formation activity and 100 % selectivity at the H2(g) partial pressure of 0.1 bar and reaction temperature 873.15 K, which is superior to previously reported Pt, Pt3Sn, 1Pt3Sn@4Pt, Pd1-NDG, Pt2/Al2O3 and Rh/ZrO2 catalysts. H* adsorption energy is proposed as a descriptor to quickly evaluate C2H4(g) formation activity. This work provides a useful strategy for designing alkane dehydrogenation catalysts by tuning monolayer shell structure and coordination environment of active site.

Pemanfaatan Cangkang Kerang Darah Sebagai Katalis dan Filter Rokok Sebagai Adsorben Dry Washing dalam Pembuatan Biodiesel Minyak Kesambi

These three wastes can be used as raw materials for biodiesel in the transesterification and purification processes. The purpose of this study was to determine and analyze the variations of blood clam shell catalysts and cigarette butt adsorbents and to compare the most optimal quality of biodiesel (producing the highest yield) based on SNI 7182:2015. The method used in this research consists of FFA testing, degumming, esterification, tranesterification and purification processes. In the transesterification process, a catalyst was added in the range of 2-6% m/v and 75% methanol, while in the refining process, active charcoal filter cigarette adsorbents were added in the range of 5-10% m/v. The data obtained was subjected to statistical analysis using the Response Surface Methodology (RSM) Central Composite Design (CCD) method. Based on statistical analysis, a linear model equation was obtained and there were no optimum and minimum points. This research also obtained the highest bisodiesel yield of 73.33% at a catalyst concentration of 6% m/v and adsorbent of 5% m/v. Some of the quality characteristics of the biodiesel produced are in accordance with SNI standards.

Non-oxidative ethane dehydrogenation reaction over molybdenum and chromium incorporated MgO encapsulated carbon-core catalysts in microwave reactor

Chromium and molybdenum incorporated MgO and MgO–C catalysts were synthesized for hydrogen production from a non-oxidative ethane dehydration reaction. Hydrogen production studies were carried out using a microwave-heated reactor system. The study investigated the effects of reaction temperature, type of active metal, and catalyst preparation method (physical mixture or core–shell structure) on hydrogen selectivity and ethane conversion during dehydrogenation reactions. The results showed that the optimal reaction temperature for the non-oxidative ethane dehydration reaction was 450 °C. Above this temperature, the selectivity of undesired byproducts increased. Catalysts containing molybdenum exhibited higher ethane conversion. Moreover, a comparison of MgO–C-supported catalysts with MgO-supported catalysts revealed that the core–shell catalysts exhibited superior ethane conversion. Notably, the 5Mo@MgO–C catalyst demonstrated exceptional catalytic activity, achieving a high ethane conversion rate of 72% along with excellent stability.

Core–Shell Catalyst Pellets for Reaction Heat Release Control in Fixed-Bed Reactors

Core–Shell Catalyst Pellets for Reaction Heat Release Control in Fixed-Bed Reactors

ZSM-5@Zn/ZSM-5 core@shell nanocrystals as integrated catalysts for efficient methanol conversion into aromatics

The use of ZSM-5@Zn/ZSM-5 core@shell nanocrystals as integrated catalyst for efficient aromatic production from methanol aromatization is demonstrated. By combining the attributes associated with core@shell structural and acidic features, ZSM-5@Zn/ZSM-5 exhibited synergistic and improved catalytic performance toward methanol aromatization. The effect of Zn/ZSM-5 shell thickness and the acid density of the ZSM-5 core on synergistic performance was systematically investigated. Results showed that aromatic selectivity could be increased with shell thickness and the acid density of the ZSM-5 core, while catalytic stability was subject to the optimization on both shell thickness and core acid density. The strengthening of dehydroaromatization on the shell catalyst after Zn introduction and the hydrogen transfer for aromatization with increasing core acid density was confirmed. A double boost on catalytic stability from methanol conversion along with 40.7% increase on aromatic selectivity could be achieved for core@shell catalyst with a coating ratio of 0.3 compared with that on single core catalyst. The fabrication of ZSM-5 core with low SiO2/Al2O3 ratio for Zn/ZSM-5 not only provided more acid sites to promote the aromatization, but also promoted the dealkylation of the formed aromatics, which could enhance the selectivity of light aromatics and catalytic lifetime. The findings in the work not only enrich the family of core@shell composite zeolite catalysts, but also provide the fundamental understanding on the aromatization process over core@shell structural features.

Exploring the effect of different precursor materials on Fe-loaded biochar catalysts for toluene removal

Rice husks, camphor tree leaves, and corn stalks were selected as raw materials from shell, leaf, and stem biomass, respectively, to prepare Fe-loaded biochar catalysts, and the removal efficiency of toluene by the three catalysts was determined. The removal efficiencies of shell catalyst (ARHB-Fe) and stem catalyst (ACSB-Fe) were 89.68% and 90.97%, respectively, both lower than that of leaf catalyst (ACLB-Fe), which was 92.01%. ARHB-Fe and ACSB-Fe exhibited a fibrous structure, while ACLB-Fe exhibited a three-dimensional honeycomb structure. ARHB-Fe had the largest specific surface area at 284.65 m²/g, exhibiting excellent physical adsorption performance for toluene. A cross-comparison of the existing forms of Fe in the three catalysts was conducted. The highest Fe2+ content in ARHB-Fe was 45.64%. The highest Fe3+ content in ACLB-Fe was 46.76%. Fe3+ underwent electrostatic reactions with the benzene ring, enhancing the adsorption of toluene. The highest Fe3C content in ACSB-Fe was 18.20%. At high temperatures, Fe3C decomposed to produce Fe0, possessing strong reducing ability and high reactivity, which effectively promoted the catalytic cracking of toluene. ARHB-Fe and ACSB-Fe were mainly influenced by n–π interactions (C–O functional groups). ACLB-Fe exhibited the combined effects of hydrogen bonding interactions (–OH functional groups), n–π interactions, and π–π interactions (CC functional groups). Furthermore, ACLB-Fe possessed the most abundant acidic sites and the highest acidity.

Explainable AI for optimizing oxygen reduction on Pt monolayer core–shell catalysts

AbstractAs a subfield of artificial intelligence (AI), machine learning (ML) has emerged as a versatile tool in accelerating catalytic materials discovery because of its ability to find complex patterns in high‐dimensional data. While the intricacy of cutting‐edge ML models, such as deep learning, makes them powerful, it also renders decision‐making processes challenging to explain. Recent advances in explainable AI technologies, which aim to make the inner workings of ML models understandable to humans, have considerably increased our capacity to gain insights from data. In this study, taking the oxygen reduction reaction (ORR) on {111}‐oriented Pt monolayer core–shell catalysts as an example, we show how the recently developed theory‐infused neural network (TinNet) algorithm enables a rapid search for optimal site motifs with the chemisorption energy of hydroxyl (OH) as a single descriptor, revealing the underlying physical factors that govern the variations in site reactivity. By exploring a broad design space of Pt monolayer core–shell alloys ( candidates) that were generated from thermodynamically stable bulk structures in existing material databases, we identified novel alloy systems along with previously known catalysts in the goldilocks zone of reactivity properties. SHAP (SHapley Additive exPlanations) analysis reveals the important role of adsorbate resonance energies that originate from ‐band interactions in chemical bonding at metal surfaces. Extracting physical insights into surface reactivity with explainable AI opens up new design pathways for optimizing catalytic performance beyond active sites.

Production Biodiesel from Vegetable Oils Using Duck Egg Shell Catalyst

Population growth causes energy needs to increase. Energy needs in Indonesia currently still depend on petroleum fuel. This research aims to determine the effect of the concentration of adding catalyst from egg shells on the production of biodiesel and determine the quality of biodiesel produced using egg shell catalyst. This research was carried out in 2 stages, namely catalyst preparation and the biodiesel manufacturing process. In catalyst preparation, egg shells that have been washed clean are then dried and crushed, then calcined using a furnace at a temperature of 1000°C for 7 hours. Next is the stage of making biodiesel using the conventional method which is carried out with variations in catalyst concentration of 1%, 2%, 3%, 4% and 5% (w/w). The research results showed that the best product yield was 78% at a concentration of 3% in 2 hours with a specific gravity of 0.889 gr/cm3 and a viscosity of 5.74 cSt.