Enhancement of the catalytic performances and lifetime of Ni/γ-Al2O3 catalysts for the steam toluene reforming via the combination of dopants: inspection of Cu,Co, Fe,Mn, and Mo species addition

In this work, the influence of metallic dopant addition in 10 wt % Ni/γ-Al₂O₃ catalyst on the material physico-chemical properties and catalytic activity for the toluene steam reforming was studied. Seventeen doped Ni/γ-Al₂O₃ catalysts were synthesized by the sol–gel process. The aim of this study was to determine which elements were the most suitable for the doping of 10 wt % Ni/γ-Al₂O₃ catalysts. The influence of the dopants was studied through different physico-chemical techniques. It appeared that some dopants showed lower catalytic performances due to high carbon deactivation. On the contrary, some dopants increased the resistance to coking while also improving the catalytic activity. Different mechanisms were proposed to explain these modifications of catalytic behavior. Among all doped Ni/γ-Al₂O₃ catalysts, the samples that combined Mn + Mo or Co + Mo dopants showed the best catalytic performances at 650 °C. Both samples showed high toluene reforming activity and low amounts of carbon deposit.     

Versatile carbon supported mono and bimetallic nanocomposites: synthesis,characterization and their potential application for furfural reduction

Biomass conversion has been developed by testing various metal based carbon catalysts. Most of the reported catalysts either use very expensive metals or support that provides lower selectivity. In this context, we fabricated new carbon based nanocomposites and studied their catalytic application for furfural reduction – a promising biomass derived molecule. The mono (Cu, Co and Ni) and bimetallic (CuCo and CuNi) nanoparticle supported on commercial graphite (CG) were prepared and characterized by TEM, EDS, XRD and Raman spectroscopy. The analysis revealed that the nanocomposites are made up of metallic nanoparticles with average particle size of 5–13 nm on the graphite matrix. The obtained results indicated that the Cu+Ni@CG catalyst exhibited high catalytic activity for furfural reduction, thus leaving Cu+Ni as the finest and cost effective catalyst for this study.     

Biochar-Based Graphitic Carbon Nitride Adorned with Ionic Liquid Containing Acidic Polymer: A Versatile,Non-Metallic Catalyst for Acid Catalyzed Reaction

A novel biochar-based graphitic carbon nitride was prepared through calcination of Zinnia grandiflora petals and urea. To provide acidic and ionic-liquid functionalities on the prepared carbon, the resultant biochar-based graphitic carbon nitride was vinyl functionalized and polymerized with 2-acrylamido-2-methyl-1-propanesulfonic acid, acrylic acid and the as-prepared 1-vinyl-3-butylimidazolium chloride. The final catalytic system that benefits from both acidic (–COOH and –SO₃H) and ionic-liquid functionalities was applied as a versatile, metal-free catalyst for promoting some model acid catalyzed reactions such as Knoevenagel condensation and Biginelli reaction in aqueous media under a very mild reaction condition. The results confirmed high activity of the catalyst. Broad substrate scope and recyclability and stability of the catalyst were other merits of the developed protocols. Comparative experiments also indicated that both acidic and ionic-liquid functionalities on the catalyst participated in the catalysis.     

Selective Oxidation of Ethane to Acetic Acid Catalyzed by a C-Scorpionate Iron(II) Complex: A Homogeneous vs. Heterogeneous Comparison

The direct, one-pot oxidation of ethane to acetic acid was, for the first time, performed using a C-scorpionate complex anchored onto a magnetic core-shell support, the Fe₃O₄/TiO₂/[FeCl₂{κ³-HC(pz)₃}] composite. This catalytic system, where the magnetic catalyst is easily recovered and reused, is highly selective to the acetic acid synthesis. The performed green metrics calculations highlight the “greeness” of the new ethane oxidation procedure.     

Highly Selective Production of Ethylene by the Electroreduction of Carbon Monoxide

Conversion of carbon monoxide to high value‐added ethylene with high selectivity by traditional syngas conversion process is challenging because of the limitation of Anderson‐Schulz–Flory distribution. Herein we report a direct electrocatalytic process for highly selective ethylene production from CO reduction with water over Cu catalysts at room temperature and ambient pressure. An unprecedented 52.7 % Faradaic efficiency of ethylene formation is achieved through optimization of cathode structure to facilitate CO diffusion at the surface of the electrode and Cu catalysts to enhance the C?C bond coupling. The highly selective ethylene production is almost without other carbon‐based byproducts (e.g. C₁–C₄ hydrocarbons and CO₂) and avoids the drawbacks of the traditional Fischer–Tropsch process that always delivers undesired products. This study provides a new and promising strategy for highly selective production of ethylene from the abundant industrial CO.     

Gold and Carbene Relay Catalytic Enantioselective Cycloisomerization/Cyclization Reactions of Ynamides and Enals

The combined use of gold as transition metal catalyst and N‐heterocyclic carbene (NHC) as organic catalyst in the same solution for relay catalytic reactions was disclosed. The ynamide substrate was activated by gold catalyst to form unsaturated ketimine intermediate that subsequently reacted with the enals (via azolium enolate intermediate generated with NHC) effectively to form bicyclic lactam products with excellent diastereo‐ and enantio‐selectivities. The gold and NHC coordination and dissociation can be dynamic and tunable events, and thus allow the co‐existence of both active metal and carbene organic catalysts in appreciable concentrations, for the dual catalytic reaction to proceed.     

π‐Interactions between Cyclic Carbocations and Aromatics Cause Zeolite Deactivation in Methanol‐to‐Hydrocarbon Conversion

The understanding of catalyst deactivation represents one of the major challenges for the methanol‐to‐hydrocarbon (MTH) reaction over acidic zeolites. Here we report the critical role of intermolecular π‐interactions in catalyst deactivation in the MTH reaction on zeolites H‐SSZ‐13 and H‐ZSM‐5. π‐interaction‐induced spatial proximities between cyclopentenyl cations and aromatics in the confined channels and/or cages of zeolites are revealed by two‐dimensional solid‐state NMR spectroscopy. The formation of naphtalene as a precursor to coke species is favored due to the reaction of aromatics with the nearby cyclopentenyl cations and correlates with both acid density and zeolite topology.     

Preparation of Ag/C fiber with nanostructure through in situ thermally induced redox reaction between PVA and AgNO3 and its catalysis for 4‐nitrophenol reduction

A novel synthesized Ag/C fibrous catalyst based on in situ thermally induced redox reaction of PVA/AgNO₃ composite fibers was proposed. Utilizing the plasticization and complexation of AgNO₃ solution, the melt spinning of PVA/AgNO₃ composites was accomplished. Through the in situ thermally induced redox reaction on PVA/AgNO₃ composite fibers combined with carbonization of PVA and reduction of Ag+, the synthesized Ag/C fibrous catalyst was prepared with nanosilver particles with average diameter of 130 nm immobilized on the loose microstructural carbon layers. The synthesized Ag/C fibrous catalyst exhibited excellent catalytic activity and reused for at least five cycles for the reduction of 4‐nitrophenol, which may hold great promise in effective and eco‐friendly waste water treatment.     

反应条件对铜催化CO2电还原的影响

工业规模的化石能源消耗导致大气中二氧化碳含量不断增加,CO₂转化利用成为人们日益关注的热点问题. 金属铜因其成本低廉、储量丰富,并且具有独特的CO₂亲和力能够生成多碳化合物,是目前CO₂电还原中研究最为广泛深入的电极材料. 由于阴、阳离子的特征吸附对Cu电极性能有显著影响,并且不同反应体系中对Cu电极上CO₂吸附、活化影响也有所不同,因此导致金属Cu电极上报道的电催化活性、产物种类与选择性等都非常宽泛. 基于此,有必要系统地研究各种反应条件对金属Cu电极电催化CO₂还原性能的影响. 作者选择了平均粒径为600 nm的商品化金属Cu颗粒作为电还原CO₂的催化剂,研究了不同反应条件包括各种常用电解质溶液、KHCO₃的浓度以及H型电解池和流动池. 实验结果表明,浓度为0.5 mol·L ^-1的KHCO₃作为电解质溶液具有较好催化活性和较高的产物分电流密度,流动池可以进一步提高主要产物甲酸盐和CO的分电流密度. 本研究工作从反应条件的角度对CO₂还原的电催化转化进行了系统研究,有助于理解电解液和反应器等因素对CO₂电还原反应过程的影响规律.     

Aluminum chloride-functionalized silica gel synthesis as a catalyst for the preparation of biologically active oxazolidinethiones: Antioxidant and molecular docking studies

The aim of this research paper was the preparation of aluminum chloride bonded to silica gel catalyst and its application in the modification of steroidal molecules. Steroidal oxazolidinethiones were prepared using silica-supported aluminum chloride (SiO₂-AlCl₃) under Microwave irradiation, which is common in organic synthesis to achieve high yields in shorter reaction times. The advantage of this method is that the usual procedure can be carried out without tiring and without a secondary product at the end of the reaction. Physicochemical techniques were used to identify the chemical structure of the prepared oxazolidinethiones. A rationalization of the conversion pathways from steroidal epoxides to oxazolidinethiones is sketched on the basis of current and previous results. Antioxidant activities i.e. DPPH assay, total antioxidant capacity and total reductive capability were performed for steroidal compounds, including reactants, and the results indicated that steroidal oxazolidinethione with acetoxy group had a promising activity among the tested steroids. In correlation with antioxidant activity, a promising steroid derivative was subjected to a molecular docking study for binding to tyrosine kinases, the target protein and showed a negative binding energy −7.8 Kcal/mol suggesting good affinity to the active pocket and can be considered as a better antioxidant in the biological system.