Enhanced Catalytic Properties of Molybdenum Promoted Mesoporous Cobalt Oxide: Structure‐Surface‐Dependent Activity for Selective Synthesis of 2‐Substituted Benzimidazoles

Abstract

High‐valent molybdenum ions were substituted into the cobalt oxide lattice through a one step, sol‐gel method and investigated for selective synthesis of 2‐substituted benzimidazoles. Catalyst synthesis involves surfactant assisted soft templating inverse micelle method, which forms mesopores by interconnected intraparticle voids. Substitutional doping of Mo6+ resulted in materials with modified structural, morphological, surface, and redox properties. The catalytic activity increased with Mo concentration until an optimum amount (3 % Mo incorporation). Modified material shows lattice expansion, increased surface oxygen vacancies, and high surface area, which are responsible for the higher catalytic activity in selective benzimidazole synthesis reaction. A strong correlation between surface properties of the catalyst and the product selectivity was observed and plausible mechanistic and kinetic data are proposed and collected, respectively.

Cobalt-Molybdenum Oxides for Effective Coupling of Ethane Activation and Carbon Dioxide Reduction Catalysis

“…This change is much larger than that observed in the bimetallic 8CoO–13.5MoO x catalyst (Figure ), where only 15.8% of Co atoms are reduced. This result confirms that, without Mo, Co species are more reducible, that is, Co 3 O 4 or CoO species (in the monometallic 10CoO catalyst) are more likely to be reduced to metallic Co particles than the Co embedded in the CoMoO 4 structures, as also reported by others. − As established, metallic Co, , together with other late transition metals (Ni, , Pt, ,, Pd, Ru, − Rh , ), is extremely reactive for alkane reforming reactions rather than the oxidative dehydrogenation reaction. The reduced 10CoO sample displayed much higher turnovers, >20 times higher than those of CoO–MoO x series, but these C 2 H 6 turnovers led exclusively to reforming products (CO and H 2 ) without producing any ethylene.…”

Microwave Hydrothermal Synthesis of Mesoporous First-Row Transition Metal Ferrites

“…These materials show exceptional catalytic activity in many applications. 18,19,21,22,36 The surface area, pore sizes, and nanocrystallinity of these materials are tunable. 27 Based on the synthesis procedure, 2-line ferrihydrite (UCT-5), which is an amorphous mesoporous iron oxide, was synthesized.…”

“…The interest in multivalent mesoporous transition metal oxides originates from their catalytic, electronic, sorption, and magnetic properties, which are superior to those of the respective nonporous material. , Mesoporous structures possess interconnected networks and high surface areas and have shown advantages when used for different catalytic applications, with improved characteristics such as electron transport, dye loading, electrolyte permeation, and oxidative capabilities when compared to those of typical nanostructured catalysts . Our lab has done a considerable amount of work on the synthesis of mesoporous metal oxides in the past few years. − The structural properties of tunable metal oxides, such as surface area, pore volume, and size, and nanocrystalline walls make this oxide class attractive. Expanding these studies to mixed metal oxides has been of interest in the hope that combining the unique advantages of the previously reported inverse micelle synthesis of mesoporous materials with those of mixed metal oxide systems would yield superior catalysts.…”

Graphene Oxide: An Efficient and Recyclable Nano Catalyst for the Synthesis of 2-Substituted Benzimidazoles from Aldehydes and Diamines at Ambient Temperature

“…Finally, high yields, simple and comfortable separate operation provided several special advantages this protocol. [52,54] The suggested mechanism for the graphene oxide-catalyzed synthesis of 2-substituted benzimidazoles has been described by a sequence of reactions as shown in Scheme 18. This involves formation of GO-activated of aldehyde carbonyl groups 1 following nucleophilic attacking of ophenylenediamine 3 to 2 afford benzilidine iminium 4.…”