Heterogeneous Catalyst Research Articles

Heterogeneous catalysts for electro-Fenton degradation of cytostatic drug cytarabine

In the present work, a reduced graphene oxide (rGO) modified-Fe3O4 doped bifunctional carbon felt cathode (rGO-Fe3O4/CF) that is capable of generating and converting H2O2 into hydroxyl radicals (•OH) on-site was fabricated, thus removing the need for an external catalyst. In addition, an rGO-modified cathode (rGO/CF) with high H2O2 production efficiency and a heterogeneous Fenton catalyst (CNT-Fe3O4) with magnetic properties were fabricated. The study examined the degradation and mineralization of the cytostatic drug cytarabine (CYT) using two HEF configurations: (i) a bifunctional cathode rGO-Fe3O4/CF and (ii) a combination of the rGO/CF cathode with CNT-Fe3O4 catalyst. The effects of parameters such as catalyst concentration, initial pH, and applied current were studied. HPLC and ion chromatography analyses were used to identify carboxylic acids and inorganic end-products, respectively. The results show that 0.1mM CYT was completely degraded within 18min at an applied current of 300mA in the HEF system with the rGO-Fe3O4/CF bifunctional cathode. Total organic carbon (TOC) analysis revealed that the bifunctional cathode system achieved 98.2% mineralization of CYT after 4h of treatment at 300mA. Using the rGO/CF cathode and CNT-Fe3O4 catalyst cell, total degradation of 0.1mM CYT occurred within 7min, and nearly total mineralization (97.3% TOC removal) was achieved at 300mA after 4h.

Electronic interactions between neighboring functionalized guest Sb single atoms and Pt clusters enhance CO tolerance

Platinum-based (Pt) catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide (CO) poisoning. Overcoming this poisoning deactivation of Pt-based catalysts while enhancing their catalytic activity, selectivity, and durability remains a major challenge. Herein, we propose a strategy to enhance the CO tolerance of Pt clusters (Ptn) by introducing neighboring functionalized guest single atoms (such as Fe, Co, Ni, Cu, Sb, and Bi). Among them, antimony (Sb) single atoms (SAs) exhibit significant performance enhancement, achieving 99% CO selectivity and 33.6% CO2 conversion at 450 °C. Experimental results and density functional theory (DFT) calculations indicate the optimization arises from the electronic interaction between neighboring functionalized Sb SAs and Pt clusters, leading to optimal 5d electron redistribution in Pt clusters compared to other functionalized guest single atoms. The redistribution of 5d electrons weaken both the σ donation and π backdonation interactions, resulting in a weakened bond strength with CO and enhancing catalyst activity and selectivity. The redistribution of 5d electrons weaken both the σ donation and π backdonation interactions, resulting in a weakened bond strength with CO. In situ environmental transmission electron microscopy (ETEM) further demonstrates the exception thermal stability of catalyst, even under H2 at 700 ℃. Notably, the functionalized Sb SAs also improve CO tolerance in various heterogenous catalysts, including Co/CeO2, Ni/CeO2, Pt/Al2O3, and Pt/CeO2-C. This finding provides an effective approach to overcome the primary challenge of CO poisoning in Pt-based catalysts, making their broader applications in various industrial catalysts.

Heterogeneous bismuth catalyst for the selective hydrogenation of nitroarenes to arylamines using molecular hydrogen

Heterogeneous bismuth catalyst for the selective hydrogenation of nitroarenes to arylamines using molecular hydrogen

A stable Bi-functional 2D Zn(Ⅱ)-CP as efficient heterogeneous solvent-free catalyst for the formation of C−C bond reactions

A stable Bi-functional 2D Zn(Ⅱ)-CP as efficient heterogeneous solvent-free catalyst for the formation of C−C bond reactions

Enhanced Phthalate Degradation in Sewage Plant by Heterogeneous Electro-Fenton modifiedd bimetallic Single-Atom Catalyst

Enhanced Phthalate Degradation in Sewage Plant by Heterogeneous Electro-Fenton modifiedd bimetallic Single-Atom Catalyst

A Novel Reusable Polymer Supported Palladium Catalyst for HeckReaction

With the rapid development of “green” chemistry; researchers are highly interested towards more sustainable approaches and prefer to choose eco-friendly synthetic routes and materials. This paper deals with the development of a novel reusable heterogeneous palladium catalyst for Heck reaction. The catalyst (mPAN-Pd) was developed by a simple procedure via synthetic modification of polyacrylonitrile (PAN) with monoethanolamine (MEA) followed by complexation with palladium chloride (PdCl2). After detailed characteristic studies, the catalytic efficiency of mPAN-Pd in Heck coupling reaction was systematically evaluated and optimised the reaction condition through a set of experiments. This heterogeneous catalytic system was found be applicable over a series of aryl halides and terminal alkenes leading to corresponding coupling products in good yields. Furthermore, this catalyst offers easy recyclability by simple filtration and reused for at least 5 cycles of Heck reaction without losing much of its activity.

CatTestHub: A benchmarking database of experimental heterogeneous catalysis for evaluating advanced materials

CatTestHub: A benchmarking database of experimental heterogeneous catalysis for evaluating advanced materials

Oxalamide-derived ionic polymer/carbon nanotube composites: Highly active heterogeneous catalyst for promoting cycloaddition of carbon dioxide to epoxides

Oxalamide-derived ionic polymer/carbon nanotube composites: Highly active heterogeneous catalyst for promoting cycloaddition of carbon dioxide to epoxides

Solid waste derived heterogeneous catalysts for synthesis of sustainable glycerol carbonate from glycerol

Solid waste derived heterogeneous catalysts for synthesis of sustainable glycerol carbonate from glycerol

Single-Atom Metal Species as A Promoter to Enhance Heterogeneous Catalysis.

Single-atom catalysts (SACs) have emerged as a focal point of research in the field of heterogeneous catalysis. This paper reviews the progress in the studies of single atoms as promoters in various catalytic reactions, elucidating their distinctive role in comparison to the dominant active sites. We provide a discussion on the application of single-atom promoters (SAP) within host-guest systems in various catalysts, including metal oxide supported catalysts, molybdenum carbide-based catalysts, bimetallic catalysts, and others. The behavior of SAP is diverse. They often promote the formation of oxygen vacancies for oxide support, leading to local site reconstruction that creates specific reaction route. Moreover, they can also precisely modify the electronic structure of hetero-metal atomic or nanoparticle sites, then regulating the adsorption of reactants or intermediates and catalytic performance. Finally, the potential for the development of SAP is outlined, proposing novel approach for the design of SACs with enhanced activity and stability.

N-Hydroxyphthalimide/TiO2 Catalyzed Addition of Ethers, Alkylarenes and Aldehydes to Azodicarboxylates under Visible Light.

The addition of carbon-centered radicals to double bonds is one of the most atom-efficient approaches to the formation of new C-C or C-heteroatom bonds. Existing approaches for the generation of carbon-centered radicals often require elevated temperatures, UV radiation or expensive transition metal catalysts. In this work, a photocatalytic system based on a heterogeneous TiO2 catalyst and a redox organocatalyst N-hydroxyphthalimide is proposed for the generation of carbon-centered radicals from C(sp3)-H substrates or aldehydes at room temperature under visible light irradiation. The developed approach was successfully applied to the coupling of ethers, alkylarenes and alhehydes with azodicarboxylates. Titanium oxide was used to initiate the organocatalytic process involving phthalimide-N-oxyl radicals in solution. Phthalimide-N-oxyl radicals act as photosensitizer and catalytically active species that cleave C-H bonds to form carbon-centered radicals.

Facing the "Cutting Edge:" Edge Site Engineering on 2D Materials for Electrocatalysis and Photocatalysis.

The utilization of 2D materials as catalysts has garnered significant attention in recent years, primarily due to their exceptional features including high surface area, abundant exposed active sites, and tunable physicochemical properties. The unique geometry of 2D materials imparts them with versatile active sites for catalysis, including basal plane, interlayer, defect, and edge sites. Among these, edge sites hold particular significance as they not only enable the activation of inert 2D catalysts but also serve as platforms for engineering active sites to achieve enhanced catalytic performance. Here it is comprehensively aimed to summarize the state-of-the-art advancements in the utilization of edge sites on 2D materials for electrocatalysis and photocatalysis, with applications ranging from water splitting, oxygen reduction, and nitrogen reduction to CO2 reduction. Additionally, various approaches for harnessing and modifying edge sites are summarized and discussed. Here guidelines for the rational engineering of 2D materials for heterogeneous catalysis are provided.

Accelerated Design of Dual-Metal-Site Catalysts via Machine-Learning Prediction.

Dual-metal site catalysts (DMSCs) supported on nitrogen-doped graphene have shown great potential in heterogeneous catalysis due to their unique properties and enhanced efficiency. However, the precise control and stabilization of metal dimers, particularly in oxygen activation reactions, present significant challenges in practical applications. In this study, we integrate high-throughput density functional theory calculations with machine learning techniques to predict and optimize the catalytic properties of DMSCs. Transfer learning is employed to enhance the model's generalization capability, successfully predicting catalytic performance across new metal combinations. Additionally, the application of the SISSO method enables the derivation of interpretable symbolic regression models, revealing critical correlations between electronic structure features and catalytic efficiency. This approach not only advances the understanding of dual-metal site catalysis but also provides a novel framework for the systematic design and optimization of highly efficient catalysts, with broad applicability in catalytic science.

Designing Supported Nanoparticles via Synergistic Ex-Solution and Phosphorization for Tailored Active Site Generation.

Supported nanoparticles incorporating catalytically attractive nonmetal elements have gained significant attention as a promising strategy for enhancing catalytic activity in various industrial applications. This study presents an innovative one-pot synthesis method for fabricating hybrid catalysts, which simultaneously modifies surface properties through the precipitation of nanoparticles with the concurrent incorporation of nonmetal elements. The underlying concept is to synchronize the temperature required for particle formation with that of nonmetal incorporation by adjusting the oxygen chemical potential of the host oxide. As a case study, Ir- and Ru-doped WO3 are selected as the starting material, with phosphorus (P) as the representative nonmetal for surface functionalization. Notably, the hybrid catalyst, composed of amorphous (Ir,Ru)Px particles dispersed on P-rich WO2.9 sheets, is synthesized through a single heat treatment at 500°C, avoiding undesirable sintering of the host material. When used as a hydrogen evolution catalyst, this material exhibits outstanding mass activity, durability, compared to state-of-the-art Pt/C catalysts. Density functional theory calculations further reveal that the superior performance of the hybrid catalysts attributes to improved water dissociation and favorable adsorption and desorption of key reaction intermediates. This novel synthesis strategy offers considerable potential for advancing diverse areas of heterogeneous catalysis.

Synergizing Mg Single Atoms and Ru Nanoclusters for Boosting the Ammonia Borane Hydrolysis to Produce Hydrogen.

Development of efficient catalysts with high H2O molecule activation ability holds great importance for H2 production. Herein, enzyme-mimic Mg single atoms catalysts (SACs) coordinated by B/N-doped carbon nanotube (BNC), was constructed as a high-performance support for ruthenium (Ru) nano-clusters. Dual functions of Mg SACs were discovered, where the Mg atoms beneath Ru catalysts built an interfacial electron polarization, inducing electron transfer from Ru to the Mg-BNC support. In addition, the oxyphilic Mg SACs adjacent to the Ru catalysts could actively participate in H2O adsorption. The combination of experimental characterization, reaction kinetics study and density functional theory (DFT) calculations validated a stronger intrinsic H2O activation capability at the positive Ru sites. Meanwhile, the synergistic Mg SACs jointly contribute to the acceleration of the sluggish H2O dissociation process in ammonia borane (AB) hydrolysis reaction, resulting in exceptional hydrogen production activity and catalytic stability, outperforming most state-of-the-art Ru-based catalysts. This work provides a new strategy for utilizing alkaline earth metals as both the electronic promoter and the reactant activator, offering inspiration for the development of advanced heterogeneous catalysts.

Valorization of nano-scrap carbon iron filings as heterogeneous electro-Fenton catalyst for the removal of anticancer drug: insight into degradation mechanism.

This study employs mechanically synthesized nano-scrap carbon iron filings (nSCIF) as a cost-effective and sustainable catalyst in heterogeneous electro-Fenton process. The catalytic behaviour of nSCIF was studied for the oxidation of cytarabine (CBN) under the influence of various experimental parameters such as pH, catalyst dose and applied current density. The highest removal efficiency (~ 99%) was achieved in 90min of reaction at pH 3, 0.4g L-1 of nSCIF dose and applied current density of 40mAcm-2. Being a solid catalyst, nSCIF enhances the production of •OH radicals and promotes the cathodic regeneration of iron species (Fe3+ to Fe2+). The mineralization efficiency reached 78% within 3h of reaction time. The daughter products generated during the reaction were identified through mass spectrometry analysis where eight major transformation productions were identified. The degradation of CBN was mainly contributed by the oxidation of aromatic ring. These findings corroborate the potential of utilizing industrial waste in the electrocatalytic oxidation of persistent pollutant.

Ligand-Shell Cooperativity in a Bilayer Silica-Sandwiched Mixed-Metals Nanocatalyst Design for Absolute Selectivity Switch.

Unlike homogeneous metal complexes, achieving absolute control over reaction selectivity in heterogeneous catalysts remains a formidable challenge due to the unguided molecular adsorption/desorption on metal-surface sites. Conventional organic surface modifiers or ligands and rigid inorganic and metal-organic porous shells are not fully effective. Here, we introduce the concept of "ligand-porous shell cooperativity" to desirably switch reaction selectivity in heterogeneous catalysis. We present a nanocatalyst design strategy consisting of bilayer silica-sandwiched 2D mixed metal islands. The intimate 2D/2D nanoscale interfacing between porous silica layers and flat island-like mixed-metal sites, combined with organic ligands, creates a nanoconfined microenvironment that enables reliable control of molecular orientation-dependent reactivity, affording the desired product in 100% selectivity. This design simultaneously leverages the hydrophobicity and flexibility of organic ligands and the nanoscale geometric rigidity of the pores inside the inorganic silica shell. Our strategy is effective with simple amorphous silica, random Cu-alloy, and commonly used metal-coordinating ligands. We demonstrate the applicability in industrially significant reactions: selective hydrogenation of alkynes, α,β-unsaturated esters/aldehydes, and nitroarenes. Our findings offer the valuable scope of a multicomponent compact nanoscale design strategy in next-generation switchable, sustainable, and recyclable catalysis.

Metal-organic frameworks-derived CaO/ZnO composites as stable catalysts for biodiesel production from soybean oil at room temperature

Biodiesel presents a sustainable alternative to fossil fuels, yet traditional homogeneous catalysts like sodium and potassium hydroxide face challenges with separation and reuse. Calcium oxide (CaO) is an effective heterogeneous catalyst for biodiesel production, but its chemical instability under reaction conditions restricts its long-term performance. This study introduces MOF-mediated synthesis (MOFMS) of heterogeneous catalysts, specifically CaO@ZnO and ZnO@CaO nanocomposites, from inexpensive and non-toxic metal salts and linkers in water. Comprehensive characterization techniques, including XRD, FT-IR, BET, FE-SEM, ICP, and CO2-TPD, were employed to analyze these catalysts. When applied to biodiesel production from soybean oil at ambient temperature and pressure, CaO@ZnO and ZnO@CaO achieved impressive biodiesel conversion rates of 99% and 92%, respectively, within 25 min. Both catalysts maintained their activity over six utilization cycles, with Ca²⁺ leaching remaining below 4% (2% for CaO@ZnO and 4% for ZnO@CaO) after the sixth run. These results provide valuable insights into catalyst preparation and leaching control, enhancing reusability in biodiesel production. Future research should aim to improve the long-term stability and reusability of these catalysts, investigate their performance with various feedstocks, and evaluate the feasibility for industrial applications.

Production of biodiesel from hemp oil and oleic acid with sulfonated camphor catalysts is to be evaluated with controlled tests in a diesel engine

Abstract This research examines the performance variables, combustion, and the amounts of NOx, CO, HC, and K emissions in a diesel engine, using blends of hemp biodiesel and oleic acid biodiesel with conventional diesel. To obtain biodiesel from hemp oil and oleic acid, a heterogeneous sulfonated camphor catalyst (CASU-AL) was used for the transesterification of hemp oil and the esterification of oleic acid respectively. Several characterization tests were performed on the CASU-AL catalyst such as the acid-base titration method for the quantification of acid sites, XRD analysis to determine the areas of the carbonaceous material, images and composition of CASU-AL were obtained with SEM and EDX, the porosity characteristics and surface properties were assessed with BET analysis. Constant operating conditions were used in the autogenous reactor with a temperature of 200 °C, a reaction time of 23 min, and a quantity of sulfonated camphor catalyst of 0.033 % w. Several analyses were applied to the CASU-AL, several mixtures were made with conventional diesel, and different biodiesels were obtained in the laboratory. The mixtures were conventional diesel (DIE-100), hemp oil biodiesel (BAC-100), oleic acid biodiesel (BAO-100), Diesel-BAC mixture with 30 % hemp oil biodiesel (MDBAC-30), and Diesel-BAO mixture with 30 % oleic acid biodiesel (MDBAO-30). For the tests in a diesel engine, three speed zones were selected in the engine to identify the behavior at low speed at 1,200 rpm, medium speed at 1,400 rpm, and high speed at 1800 rpm. Combustion tests reveal that no significant variation is observed in the characteristics and performance of the diesel engine, however, in the gaseous products derived from combustion, significant reductions in carbon monoxide, unburned hydrocarbon, and an increase in nitrogen oxide emissions were achieved when using DIE-100 compared to BAC-100 and BAO-100. The tests showed a reduction in NOx, CO, HC, K, and smoke emissions when testing MDBAC-30 and MDBAO-30 in a laboratory diesel engine. A comparison of the properties of hemp oil-oleic acid biodiesels BAC-100 and BAO-100 with conventional diesel DIE-100 revealed that the different biodiesels used could be used alone or in a blend of 70 % diesel and 30 % biodiesel to fuel diesel engines by decreasing air pollutants and promoting lubricity in the engine. Our findings revealed that MDBAC-30 and MDBAO-30 showed the best engine performance and lowest emissions among all the tested fuels. In other words, MDBAC-30 and MDBAO-30 are the ideal fuel blends for diesel engines and do not require any modification to the engine.

A Highly Dispersed Heterogeneous Cobalt Catalyst for Efficient Domino Hydroformylation Reductive Amination of Olefins

A Highly Dispersed Heterogeneous Cobalt Catalyst for Efficient Domino Hydroformylation Reductive Amination of Olefins