Heterogeneous Catalyst Research Articles

Design of low temperature La2O3 oxidative coupling of methane catalysts using feature engineering and automated sampling

Machine learning with feature engineering is employed to design heterogeneous catalysts for the oxidative coupling of methane, resulting in the identification of four active catalysts whose catalytic activities are experimentally validated.

Sustainable fabrication of NiCuFe2O4 nanospheres: a highly effective palladium-free heterogeneous catalyst for biaryl scaffold synthesis via a Suzuki–Miyaura cross-coupling reaction

Herein, a Pd-free and recyclable NiCuFe2O4 nanoparticles with hierarchical nanosphere architecture, magnetically well-separable and stable, demonstrates excellent catalytic activity in Suzuki–Miyaura cross-coupling reactions.

Comprehensive sampling of coverage effects in catalysis by leveraging generalization in neural network models

A combination of generalization in neural networks and fast data pipelines enables comprehensive sampling coverage and co-adsorption effects in heterogeneous catalyst models.

A pathway to cyclic carbonates: Cycloaddition of carbon dioxide to epoxidized methyl oleate on grafted heterogeneous catalysts

A pathway to cyclic carbonates: Cycloaddition of carbon dioxide to epoxidized methyl oleate on grafted heterogeneous catalysts

Catalytic Synthesis of Xanthene and Unprecedented Evolution of Naphthopyrans Using Heteropoly Acid‐Tantalum(V) Oxide Hybrid Composite as Promoter

AbstractXanthene derivatives are prepared by using tantalum(V) oxide (Ta2O5)‐supported heteropoly acid (HPA), Keggin 12‐phosphotungstic acid (PTA)‐based heterogeneous catalyst PTA@Ta2O5 under neat conditions. The composite is prepared by the wetness impregnation method and is characterized by various techniques. Under optimized conditions, xanthenes are synthesized with prominent yields in remarkably short reaction times. The green chemistry metrics are appraised for the xanthene reaction. Surprisingly, a few novel naphthopyran derivatives are isolated instead of the conventional xanthene derivatives when cinnamaldehyde analogous are introduced under the same reaction protocol. Unprecedented naphtho[2,1‐b]pyran‐type derivatives of 3m, 3n, and 3o are isolated, depending on the specific substituted cinnamaldehyde used, and interestingly, the nature of the substituent in cinnamaldehyde decides the different reaction pathways leading to the formation of respective pyrans. Diverse possible mechanisms are encountered with the PTA@Ta2O5 catalyst based on the respective transformations. The solid‐state structures of xanthenes and naphthopyrans are thoroughly investigated. Furthermore, some derivatives are studied in vitro to assess their antimicrobial activity, and the findings are compared with those of reference standard antibiotics.

Heterogeneous catalyst production from waste cucumber stems and investigation of production potential in biodiesel

Heterogeneous catalyst production from waste cucumber stems and investigation of production potential in biodiesel

Hydrogenation of CO2 to formic acid over non-precious metal based polymeric catalyst

Catalytic hydrogenation of CO2 using non-precious metal based heterogeneous catalyst presents significant challenge and a promising opportunity for exploration. Herein, we demonstrate the catalytic hydrogenation of CO2 using iron loaded...

Regulation of TS-1 Zeolite Morphology by Crystallization Modifiers to Boost the Oxidative Reactions

TS-1 zeolite is a heterogeneous catalyst renowned for its remarkable catalytic performance in oxidation processes, tailoring its morphology is crucial for targeted reactions. Herein, we present a facile and versatile...

Efficient Photocatalytic Degradation of RhB in Water via Co3O4 and F‐Doped Carbon Nitride Heterojunction

AbstractPhotocatalysis is an effective solution to degrade organic dye discharge in wastewater treatment due to its efficiency, environmental friendliness and cost‐effectiveness. However, issues such as limited visible light absorption and rapid charge carrier recombination hinder its practical use. In this research, the heterojunction (Co─FCN) composed of carbon fluoride nitride and cobalt tetroxide (Co3O4) was successfully prepared by a simple one‐pot pyrolysis method. The obtained nanocomposites showed their efficiency as photocatalyst in the photodecomposition of Rhodamine B (RhB). The relationship between microstructure and properties of photocatalyst was studied in detail by means of characterization techniques. The results showed that the RhB degradation efficiency of Co3─FCN was 92.91% within 60 min irradiation time. The results of free radical scavenging experiments show that superoxide anion (·O2−) and hydroxyl radical (·OH) are the main active species in Co─FCN composite catalysts. In addition, the potential degradation pathway of RhB was inferred based on the intermediates detected by liquid chromatography mass spectrometry (LC‐MS), and the preliminary photocatalytic reaction mechanism of Co─FCN heterogeneous catalyst was constructed accordingly. Therefore, this research provides new insights into the preparation and modification of CN photocatalysts, thereby promoting the application potential of efficient photocatalysts in the degradation of organic pollutants.

Biodiesel synthesis via heterogeneous catalysis: application of new material based on mixed oxides (Na-FeAlO) obtained from the microstructural transformation of red mud

ABSTRACT This paper investigated the application of a new material based on mixed oxides (Na-FeAlO) as a catalyst, which was synthesized from red mud (RM) and sodium carbonate and named CLV98/900, in the production of fatty acid alkyl esters (FAAE) from waste cooking oil (WCO) via transesterification reaction. The synthesized catalysts were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), and Fourier transform infrared spectrometer (FTIR). The characterization of the catalyst indicated that the microstructural transformation of red mud into CLV98/900 efficiently obtained new crystallographic phases. The influence of several operational parameters, such as oil/alcohol molar ratio (1/15 – 1/45), temperature (65–75°C), percentage of catalyst (0–5%) and reaction time (60–180 min), was evaluated on the yield and conversion, resulting in yield values that ranged from 2% to 74%, 25% to 67.5%, 8% to 67.5% and 2% to 74%, respectively. In parallel, the conversion values ranged from 52% to 82%, 58% to 82%, 4% to 63% and 54% to 74%, respectively. The operational parameters fixed at an oil/ethanol molar ratio of 1/30, 70°C, 1% catalyst and 60 min provide the highest yield (82%) and conversion (82%). GC-MS analysis confirmed the formation of biodiesel. Therefore, CLV98/900 shows excellent potential as a catalyst for biodiesel production via WCO transesterification.

Surface Coverage Tuning for Suppressing Over-Oxidation: A Case of Photoelectrochemical Alcohol-to-Aldehyde/Ketone Conversion.

Suppressing over-oxidation is a crucial challenge for various chemical intermediate synthesis in heterogeneous catalysis. The distribution of oxidative species and the substrate coverage, governed by the direction of electron transfer, are believed to influence the oxidation extent. In this study, we presented an experimental realization of surface coverage modulation on a photoelectrode using a photo-induced charge activation method. Through the surface coverage modulation, both pre-oxidized alcohol substrates and surface coverage were increased, which not only improved the reaction kinetics but also suppressed the over-oxidation of the generated aldehydes/ketones. As a demonstration, the Faradaic efficiency for the conversion of glycerol to dihydroxyacetone increased from 31.8 % to 46.8 % (with selectivity rising from 47.6 % to 71.3 %), from 73.4 % to 87.8 % for benzyl alcohol to benzyl aldehyde (selectivity increasing from 76.7 % to 92.4 %) and from 4.2 % to 53.6 % for ethylene glycol to glycolaldehyde (selectivity increasing from 6.2 % to 62.7 %). Our findings offer a promising strategy for the production of high-value carbon products in heterogeneous catalysis.

Reticulating Crystalline Porous Materials for Asymmetric Heterogeneous Catalysis

AbstractAsymmetric catalysis is essential for addressing the increasing demand for enantiopure compounds. Recent advances in reticular chemistry have demonstrated that metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) possess highly regular porous architectures, exceptional tunability, and the ability to incorporate chiral functionalities through their open channels or cavities. These characteristics make them highly effective and enantioselective catalysts for a wide range of asymmetric transformations. The chiral microenvironments within these frameworks facilitate precise control over reactant orientation and transition states, enhancing both catalytic activity and enantioselectivity, thereby offering significant advantages over traditional systems. This review overviews recent developments in chiral MOFs (CMOFs) and chiral COFs (CCOFs), focusing on their design strategies, and synthetic methods, and highlights the structure–property relationships that connect key structural features to asymmetric catalytic performance. Additionally, the current challenges and future prospects in this field are addressed, highlighting the pivotal role of reticular chemistry in the creation of chiral porous materials. It is anticipated that this review will inspire further research into the application of crystalline porous materials in asymmetric catalysis and promote the rational design of novel chiral heterogeneous catalysts for industrial use.

Towards Rational Design of Confined Catalysis in Carbon Nanotube by Machine Learning and Grand Canonical Monte Carlo Simulations.

The microenvironment is recognized to be as crucial as active sites in heterogeneous catalysis. It was found that the catalytic activity of a set of chemical reactions can be significantly influenced by the confined space of carbon nanotubes (CNTs), with some reactions showing superior activity, while others experience a negative impact. The rational design of confined catalysis must rely on the accurate insights of confined microenvironment. However, the structural complexity of confined catalysts and the interaction with microenvironment hinders the deciphering of chemical origins behind experiments. In this work, Grand-canonical Monte Carlo (GCMC) simulations are conducted for confined catalysis in CNTs at various reaction atmospheres, accelerated by machine learning potentials. The statistical outcomes of GCMC simulations corroborate a general feature that the electronic interaction (binding energy) inside CNTs is weaker than outside cases. By using Random Forest (RF) model, we ascertain that the shortening of the bond lengths of catalysts within the confined space is the dominant factor, resulting in the weakened binding energy and the downshift of the d-band center. Using the bond length variation as a simplified descriptor, our microkinetic models successfully reproduced the seemingly contradictive experiments, namely, the observed enhancement and suppression for the same reaction.

Towards Rational Design of Confined Catalysis in Carbon Nanotube by Machine Learning and Grand Canonical Monte Carlo Simulations

The microenvironment is recognized to be as crucial as active sites in heterogeneous catalysis. It was found that the catalytic activity of a set of chemical reactions can be significantly influenced by the confined space of carbon nanotubes (CNTs), with some reactions showing superior activity, while others experience a negative impact. The rational design of confined catalysis must rely on the accurate insights of confined microenvironment. However, the structural complexity of confined catalysts and the interaction with microenvironment hinders the deciphering of chemical origins behind experiments. In this work, Grand‐canonical Monte Carlo (GCMC) simulations are conducted for confined catalysis in CNTs at various reaction atmospheres, accelerated by machine learning potentials. The statistical outcomes of GCMC simulations corroborate a general feature that the electronic interaction (binding energy) inside CNTs is weaker than outside cases. By using Random Forest (RF) model, we ascertain that the shortening of the bond lengths of catalysts within the confined space is the dominant factor, resulting in the weakened binding energy and the downshift of the d‐band center. Using the bond length variation as a simplified descriptor, our microkinetic models successfully reproduced the seemingly contradictive experiments, namely, the observed enhancement and suppression for the same reaction.

Electronic Promoter Breaks the Linear Scaling Relationship: Ultra‐Rapid High‐Temperature Synthesis of Heterostructured CoS/SnO2@C as a Bifunctional Oxygen Catalyst for Li‐O2 Batteries

AbstractLi‐O2 batteries urgently needs high discharge capacity and stable cycling performance, requiring effective and reliable bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Hovenia acerba Lindl‐like heterostructure composed of cobalt sulfide and tin dioxide supported on carbon substrate (CoS/SnO2@C) is prepared via CO2 laser irradiation technology. The half‐wave potential of CoS/SnO2@C for the ORR is 0.88 V, while the overpotential of the OER at 10 mA cm−2 is as low as 270 mV. The Li‐O2 batteries employing the bifunctional CoS/SnO2@C catalyst displays a high discharge specific capacity of 3332.25 mAh g−1 and long cycling life of 226 cycles. Additionally, theory calculations demonstrate that the construction of heterostructure decreases energy barrier of the rate‐determining step (RDS) for both ORR and OER. Notably, SnO2 behaves as the electronic promoter to optimize the electronic structure of heterostructure interface and triggers charge redistribution of CoS, which weakens the adsorption strength of the *O‐intermediates and allows to break the linear scaling relationship, thus further enhancing the catalytic performance of CoS/SnO2@C. This research furnishes directions for the design of heterogeneous catalysts, highlighting its great potential for application in rechargeable Li‐O2 batteries.

Tailoring the Porous Structure of Carbon for Enhanced Oxidative Cleavage and Esterification of C(CO)-C Bonds.

The cleavage and functionalization of carbon-carbon bonds are crucial for the reconstruction and upgrading of organic matrices, particularly in the valorization of biomass, plastics, and fossil resources. However, the inherent kinetic inertness and thermodynamic stability of C-C σ bonds make this process challenging. Herein, we fabricated a glucose-derived defect-rich hierarchical porous carbon as a heterogeneous catalyst for the oxidative cleavage and esterification of C(CO)-C bonds. Systematic investigations revealed that the hierarchical porous structure enhances the adsorption of O2 and ketones, thereby boosting the catalytic efficiency of defects. This catalyst exhibits performance comparable to that of the reported nitrogen-doped or metal nanoparticle-supported carbon materials, as well as transition metal-based homogeneous catalytic systems. This work deepens our understanding of the reaction process underlying this transformation and provides insights for designing efficient carbon-based materials for oxidative transformations.

Hydrothermal Synthesis of Fenton Catalyst from Soybean Curd Residue Biochar for Tetracycline Degradation

In this study, heterogeneous catalysts were synthesized by hydrothermal method to load nano goethite to biochar derived from soybean curd residue, which served as catalysts for the heterogeneous degradation of tetracycline hydrochloride (TCH) in an aqueous solution. The catalytic tests using this composite material demonstrated significant TCH degradation. After 90 min of reaction, the optimum degradation of TCH in the aqueous solution was achieved. The initial pH value and TCH concentration were set at 2 and 50 mg/L, respectively, and the ambient conditions were maintained. The results showed that 0.5 g/L of catalyst and 60.0 mM H2O2 were the ideal catalyst and reagent dosages. Experimental data showed that the second-order kinetic model accurately described the degradation process than the first-order kinetic model. The study showed that biochar-loading goethite could be prepared from soybean crud residue and used for the degradation of TCH in an aqueous solution. Additionally, these results also provide a new approach for catalyst generation by the hydrothermal method that might help reduce costs and be environmentally friendly.

Stabilized Gold Nanoparticles on -Hydroxy Amide-Functionalized Graphene Oxide as a Robust Catalyst for Environmentally Benign Oxidation of Primary and Secondary Alcohols

Multi-component reactions (MCRs), one of the most powerful approaches to synthesizing complex structures from the fastest path, have grabbed much attention and have recently been used to functionalize the surface of nanomaterials. Here, we focus on an isocyanide-based multi- component reaction for one-pot functionalization of the graphene oxide surface. This led to α- hydroxy amide decorated graphene oxide with the ability to immobilize Gold nanoparticles and serve as a neoteric catalytic system. This nanocatalyst was characterized by means of SEM, TEM, ICP-OES, FTIR, XRD, Raman, and BET techniques. This employed multifunctional nanostructure as an efficient and recyclable heterogeneous aerobic catalyst for the oxidation of primary and secondary aliphatic and aromatic alcohols to their aldehydes and ketones in water at mild temperature in good to excellent yields. Further, this method showed that recycling of heterogeneous catalysts has a high possibility of being re-used with their performances as it was new with no sign of gold leaching.

Anomalous Role of Carbon in Pd‐Catalyzed Selective Hydrogenation

AbstractCarbonaceous species, including subsurface carbidic carbon and surface carbon, play crucial roles in heterogeneous catalysis. Many reports suggested the importance of subsurface carbon in the selective hydrogenation of alkynes over Pd‐based catalysts. However, the role of surface carbon has been largely overlooked. We demonstrate that subsurface carbon in Pd is not responsible for the selectivity in acetylene hydrogenation. In contrast, the structure of surface carbonaceous species plays a decisive role in hydrogenation selectivity. Electron microscopy and spectroscopy evidence, along with theoretical modelling, reveal that partial graphitization of surface carbonaceous species results in unique spatial confinement of surface reaction intermediates, thus altering the reaction energy landscape in favour of ethylene desorption as opposed to over‐hydrogenation. This mechanism for selectivity control is analogous to enzyme catalysis, where the active centers selectively attract reactants and release products. Similar mechanism may be present in CO/CO2 hydrogenation and alkane dehydrogenation reactions.

The Interfacial Interpenetration Effect for Controlled Reaction Stability of Palladium Catalysts.

Tailoring well-defined interfacial structures of heterogeneous metal catalysts has become an effective strategy for identifying the interface relationships and facilitating the reactions involving multiple intermediates. Here, a particle-particle heterostructure catalyst consisting of Pd and copper oxide nanoparticles is designed to achieve high-performance alkaline methanol oxidation electrocatalysis. The strong coupling particle-particle heterostructure catalyst induced a unique interfacial interpenetration effect to improve the interfacial charge redistribution and regulate the d-band structure for optimizing the adsorption of CO intermediates on the catalyst. The resulting catalyst shows impressive mass activity (4.0 A mgPd-1) and current density (215.8 mA cm-2) for the methanol oxidation reaction (MOR) in alkaline media, which is 80.0 and 154.1 times higher than 10% Pd/C. The catalyst also exhibited outstanding stability for the MOR without obvious mass activity decay after 30,000 cycles. Experimental results and theoretical simulation (DFT) studies show that the chemical bond of the Cu-O-Pd interface can be regulated by the Pd penetration effect, greatly improving the activity and stability of the MOR. The present work exhibits the superiority of the metal particle-metal oxide heterostructure interface toward the rational design of advanced electrocatalysts.