Development Of New Catalytic Materials Research Articles

Kinetics of Hydrogen Evolution Reaction on Monometallic Bulk Electrodes in Various Electrolytic Solutions

The hydrogen evolution reaction (HER) holds pivotal significance in electrochemical energy conversion. In this study, we present essential HER kinetic parameters encompassing nine metals (Ag, Au, Co, Cr, Fe, Ni, Pt, W, and Zn) evaluated within seven distinct electrolytes (0.1 mol dm−3 HClO4, 0.1 mol dm−3 HCl, 0.5 mol dm−3 NaCl, 1 mol dm−3 KH2PO4, 0.1 mol dm−3 KOH, 0.1 mol dm−3 LiOH, and 1 mol dm−3 KOH). Through careful measures to restrain oxide formation, HER activity was measured on clean electrodes, while the assessment of HER activity on oxidatively treated metals was also performed. By correlating HER exchange current densities with calculated hydrogen binding energies, we show that the shape of HER volcano curves is largely preserved in studied electrolytes, at least around their apexes. Additionally, depending on the metal–electrolyte combination, the presence of surface oxide can have both positive and negative effects on HER kinetics. Finally, we collated HER kinetic data for bulk surfaces from diverse literature sources, offering a comprehensive overview of the kinetic parameters governing hydrogen evolution across distinct electrolytic environments. These insights have practical significance, guiding the development of new catalytic materials for different water electrolysis technologies, optimizing electrolyte formulations for boosting HER, and enhancing energy efficiency and catalytic performance through catalyst–electrolyte synergies.

Unveiling the promoting effect of potassium on the structural evolution of iron catalysts during CO2 hydrogenation

Understanding and modulating the dynamic structural evolution is of great significance in developing high-performance heterogeneous catalysts. This work investigates the effect of potassium (K) promoter on the carburization and oxidation of Fe phases during CO2 hydrogenation over an iron-based catalyst using in-situ X-ray diffraction, in-situ infrared spectroscopy, and temperature-programmed techniques. The addition of K enhances CO2 adsorption of the catalyst, promotes the reaction of CO2 with the dissociated hydrogen, and accelerates the carburization of Fe(0) to Fe3C and then to Fe5C2. In addition to impacting the reactive microenvironment of the catalyst surface on the competitive adsorption and reactions, the addition of K also prevents the active Fe5C2 phase from oxidation during CO2 hydrogenation. With an optimized content of K and CO pretreatment, the iron-based catalysts were endowed with high catalytic activity for CO2 conversion to C2-C4 olefins and C5+ long-chain hydrocarbons. This work provides insight into the correlation between the reactive microenvironment and the structural evolution of Fe catalysts doped with K promoter and shall be beneficial for future development of new catalytic materials for CO2 hydrogenation, and possibly other reactions.

Delayed In Vivo Encapsulation of Enzymes Alters the Catalytic Activity of Virus-Like Particle Nanoreactors.

Encapsulation of enzymes inside protein cage structures, mimicking protein-based organelle structures found in nature, has great potential for the development of new catalytic materials with enhanced properties. In vitro and in vivo methodologies have been developed for the encapsulation of enzymes within protein cage structures of several types, particularly virus-like particles (VLPs), with the ability to retain the activity of the encapsulated enzymes. Here, we examine the in vivo encapsulation of enzymes within the bacteriophage P22 derived VLP and show that some enzymes may require a delay in encapsulation to allow proper folding and maturation before they can be encapsulated inside P22 as fully active enzymes. Using a sequential expression strategy, where enzyme cargoes are first expressed, allowed to fold, and later encapsulated by the expression of the P22 coat protein, altered enzymatic activities are obtained in comparison to enzymes encapsulated in P22 VLPs using a simultaneous coexpression strategy. The strategy and results discussed here highlight important considerations for researchers investigating the encapsulation of enzymes inside confined reaction environments via in vivo routes and provide a potential solution for those that have been unable to produce active enzymes upon encapsulation.

MOF-Mediated Synthesis of Supported Fe-Doped Pd Nanoparticles under Mild Conditions for Magnetically Recoverable Catalysis*.

Metal-organic framework (MOF)-driven synthesis is considered as a promising alternative for the development of new catalytic materials with well-designed active sites. This synthetic approach is used here to gradually transform a new bimetallic MOF, with Pd and Fe as the metal components, by the in situ generation of aniline under mild conditions. This methodology results in a compositionally homogeneous nanocomposite formed by Fe-doped Pd nanoparticles that, in turn, are supported on iron oxide-doped carbon. The nanocomposite has been fully characterized by several techniques such as IR and Raman spectroscopy, TEM, XPS, and XAS. The performance of this nanocomposite as an heterogeneous catalyst for hydrogenation of nitroarenes and nitrobenzene coupling with benzaldehyde has been evaluated, proving it to be an efficient and reusable catalyst.

A stable and highly selective metalloporphyrin based framework for the catalytic oxidation of cyclohexene.

A new metalloporphyrin framework of molybdenum Mo2O4(C48H28N4O8)·(CH3)2NH·5H2O·2DMF (Mo2TCPP) was synthesized from tetrakis(4-carboxyphenyl)porphyrin (H4TCPP) and sodium molybdate dihydrate by a hydrothermal method. Mo2TCPP is a 3D network with two sub-units, in which both TCPP ligands and each Mo2 dimer act as four connection nodes. The crystal structure was determined by single crystal analysis and further characterized by FTIR, SEM, EDX, PXRD, XPS and TGA. Here cumene hydrogen peroxide and hydrogen peroxide were used as oxidants to study the catalytic activity of new metalloporphyrins in the oxidation of cyclohexene at different temperatures. The conversion rate of cyclohexene and the selectivity of epoxycyclohexane were both higher than 99%, which was better than the previously published research results. The stability of the catalyst before and after the reaction was further tested for 10 runs without obvious degradation. The catalyst was stable in different solutions such as acidic, water and alkaline. These results shed light on the future development of new catalytic materials based on metalloporphyrin.

Facile Preparation of Unsubstituted Iron(II) Phthalocyanine/Carbon Nitride Nanocomposites: A Multipurpose Catalyst with Reciprocally Enhanced Photo/Electrocatalytic Activity

The development of new catalytic materials is conducive to solving the global energy crisis and environmental problems. In this work, multipurpose catalyst unsubstituted iron(II) phthalocyanine/car...

Polymer-Brush-Templated Three-Dimensional Molybdenum Sulfide Catalyst for Hydrogen Evolution.

Earth-abundant hydrogen evolution catalysts are essential for high-efficiency solar-driven water splitting. Although a significant amount of studies have been dedicated to the development of new catalytic materials, the microscopic assembly of these materials has not been widely investigated. Here, we describe an approach to control the three-dimensional (3D) assembly of amorphous molybdenum sulfide using polymer brushes as a template. To this end, poly(dimethylaminoethyl methacrylate) brushes were grown from highly oriented pyrolytic graphite. These cationic polymer films bind anionic MoS42- through an anion-exchange reaction. In a final oxidation step, the polymer-bound MoS42- is converted into the amorphous MoSx catalyst. The flexibility of the assembly design allowed systematic optimization of the 3D catalyst. The best system exhibited turnover frequencies up to 1.3 and 4.9 s-1 at overpotentials of 200 and 250 mV, respectively. This turnover frequency stands out among various molybdenum sulfide catalysts. The work demonstrates a novel strategy to control the assembly of hydrogen evolution reaction catalysts.

Support effect and metals interactions for NiRu/Al2O3, TiO2 and ZrO2 catalysts in the hydrodeoxygenation of phenol

The bio oil of pyrolysis can be upgraded via hydrodeoxygenation to remove unfavorable characteristics related to high levels of oxygen. Sulfided NiMo and CoMo catalyst have been studied extensively in hydrodeoxygenation. However, significant deactivation may occur, due to the lack of sulfur in the charges or to coke deposition, induced by strong acidic supports. Therefore, development of new catalytic materials with alternative supports and active phases is relevant. In this work, Ni, Ru, and Ni-Ru catalysts were prepared by wet impregnation of Ni(NO3)2·6H2O and Ru(NO)(NO3)3 solutions. Al2O3, TiO2, and ZrO2 were used as supports, evidencing influence on hydrodeoxygenation (HDO) of phenol activity and selectivities. TPR and XPS characterization revealed a promoter effect of ruthenium over Ni reducibility and in some cases, a synergetic effect on catalytic activity in phenol HDO reaction was observed. The metallic ruthenium particles were reduced at low temperatures, and they enhanced reduction of Ni by H2 spillover effect, due to a close contact between metals. Furthermore, TPD-NH3 indicated a possible correlation between catalyst acidity and HDO reaction rate.

Recent advances in heterogeneous selective oxidation catalysis for sustainable chemistry

Oxidation catalysis not only plays a crucial role in the current chemical industry for the production of key intermediates such as alcohols, epoxides, aldehydes, ketones and organic acids, but also will contribute to the establishment of novel green and sustainable chemical processes. This review is devoted to dealing with selective oxidation reactions, which are important from the viewpoint of green and sustainable chemistry and still remain challenging. Actually, some well-known highly challenging chemical reactions involve selective oxidation reactions, such as the selective oxidation of methane by oxygen. On the other hand some important oxidation reactions, such as the aerobic oxidation of alcohols in the liquid phase and the preferential oxidation of carbon monoxide in hydrogen, have attracted much attention in recent years because of their high significance in green or energy chemistry. This article summarizes recent advances in the development of new catalytic materials or novel catalytic systems for these challenging oxidation reactions. A deep scientific understanding of the mechanisms, active species and active structures for these systems are also discussed. Furthermore, connections among these distinct catalytic oxidation systems are highlighted, to gain insight for the breakthrough in rational design of efficient catalytic systems for challenging oxidation reactions.

Improving the Methanation Process

AbstractThe production of substitute natural gas based on coal or biomass is once again back in focus, initiated by rising natural gas prices and the desire to become independent from natural gas imports. It is necessary to optimize the commercial process, e.g., by using harsher process conditions to reduce the recycle ratio. In line with this the development of new catalytic materials as well as the understanding of the reaction kinetics to control the heat of reaction and predict the lifetime of the catalyst is required.

Chemically stable electrospun NiCu nanorods@carbon nanofibers for highly efficient dehydrogenation of ammonia borane

We describe the preparation of bimetallic NiCu nanorods (NRs) incorporated on carbon nanofibers (NFs). The synthesis nanofibers were prepared by low cost and facile technique; electrospinning. Typically, sol–gel consisting of nickel acetate, copper acetate, and poly (vinyl alcohol) was electrospun. Sintering of the electrospun nanofiber mats in argon atmosphere led to partial elimination of the utilized polymer and abnormal decomposition of the metallic acetates to finally produce NiCu nanorods incorporated in carbon nanofibers. The as-obtained nanofibers were characterized by SEM, FE-SEM, XRD, TGA, XPS, TEM, and TEM-EDX standard techniques. The introduced bimetallic nanofibers revealed superior catalytic activity toward hydrogen release from ammonia borane. Also, they showed a good chemical stability due to covering the bimetallic nanorods by carbon shells. Interestingly, nanofibers were reused for 6 successive cycles with good catalytic activity. Moreover, the prepared nanofibers showed low activation energy about 28.9 kJ/mol. Finally, development of new catalytic materials in the field of energy is considered as a key objective of the modern research.

Design of Optimum Zeolite Pore System for Central Hydrocracking of Long-Chain n-Alkanes based on a Single-Event Microkinetic Model

Model based catalyst design is an emerging methodology in the development of new catalytic materials with properties tailored to the needs of specific industrial applications. A Single-Event MicroKinetic model (SEMK) was used to assess the hydrocracking behavior of n-dodecane, 4,4,6-trimethyl nonane and 2,5,8-trimethyl nonane, on a non-selective USY zeolite. The differences in cracking pattern exhibited by the various feed molecules provide guidelines for the control of the cracked product distribution through modifications of the zeolite pore structure. The connection of ZSM-22 type channels to the zeolite Y super cage is considered in this work. The percentage of C6 products obtained by central cracking in the chain can be increased from 25% up to 93% by the design of an appropriate zeolite topology combining USY-like super cages with ZSM-22 like channel segments. This is a promising approach for the development of zeolite catalysts for the selective hydrocracking of Fischer Tropsch waxes into middle distillates.

ChemInform Abstract: Environmental Catalysis: A Push to the Development of New Catalytic Materials

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.