Immobilization of metalloporphyrin on organosilicon microsphere mixed with ceria as a new catalyst for oxidation of cyclohexane

Highly Active Catalysis of Cobalt Tetrakis(pentafluorophenyl)porphyrin Promoted by Chitosan for Cyclohexane Oxidation in Response-Surface-Methodology-Optimized Reaction Conditions

We aimed at elevating catalytic performances of cobalt tetrakis(pentafluorophenyl)porphyrin (Co TPFPP) through axial coordination, nanocavities, and covalently grafting action. The Co TPFPP was immobilized onto nanoporous and nonporous chitosan, forming Co TPFPP/np‐ and nonp‐CTS catalysts, respectively. The catalysts were characterized by various spectroscopic techniques. The catalytic performances of these catalysts for cyclohexane oxidation under response‐surface‐methodology‐optimized oxidation reaction conditions were estimated and compared. Co TPFPP/np‐CTS was an excellent catalyst at aspect of catalytic activity, exhibiting the considerable potential reusability, 24.2 mol % yields (KA oil : cyclohexanone and cyclohexanol) in average, and total turnover frequencies (TOFs) of 3.25×10⁶ h⁻¹. This is attributed to the structural characteristics of the Co TPFPP/np‐CTS catalyst: the cobalt porphyrin molecules could be highly scattered on CTS, forming the independent active sites, and were not leached. The axial coordination exerted the most important effect on the catalytic activity, and the covalent grafting action had a decisive effect on the increase of the total TOFs and on the reusability of the catalyst.

High performance of a cobalt-nitrogen complex for the reduction and reductive coupling of nitro compounds into amines and their derivatives

Replacement of precious noble metal catalysts with low-cost, non-noble heterogeneous catalysts for chemoselective reduction and reductive coupling of nitro compounds holds tremendous promise for the clean synthesis of nitrogen-containing chemicals. We report a robust cobalt-nitrogen/carbon (Co-N _x /C-800-AT) catalyst for the reduction and reductive coupling of nitro compounds into amines and their derivates. The Co-N _x /C-800-AT catalyst was prepared by the pyrolysis of cobalt phthalocyanine-silica colloid composites and the subsequent removal of silica template and cobalt nanoparticles. The Co-N _x /C-800-AT catalyst showed extremely high activity, chemoselectivity, and stability toward the reduction of nitro compounds with H₂, affording full conversion and >97% selectivity in water after 1.5 hours at 110°C and under a H₂ pressure of 3.5 bar for all cases. The hydrogenation of nitrobenzene over the Co-N _x /C-800-AT catalyst can even be smoothly performed under very mild conditions (40°C and a H₂ pressure of 1 bar) with an aniline yield of 98.7%. Moreover, the Co-N _x /C-800-AT catalyst has high activity toward the transfer hydrogenation of nitrobenzene into aniline and the reductive coupling of nitrobenzene into other derivates with high yields. These processes were carried out in an environmentally friendly manner without base and ligands.

Preparation of Co–N–C supported on silica spheres with high catalytic performance for ethylbenzene oxidation

In this study, Co–N–C supported on silica spheres is prepared through heat-treatment of supported metalloporphyrin in an N₂ atmosphere.

Influence of pH on the catalytic performance of CuO–CoOx–CeO2 for CO oxidation

Ternary catalysts, namely CuO–CoO_x–CeO₂, are prepared by coprecipitation with different pH and characterized by techniques such as N₂ adsorption/desorption, XRD, TPR, TEM and XPS.

Immobilization of metalloporphyrin on a silica shell with bimetallic oxide core for ethylbenzene oxidation

In this study, metalloporphyrin has been immobilized on a core–shell structured SiO₂@CeO₂ doped with transition metals such as Fe, Cu, Co and Mn.

A zinc sulfide-supported iron tetrakis (4-carboxyl phenyl) porphyrin catalyst for aerobic oxidation of cyclohexane

Fe TCPP/ZnS catalyst, which possessed much higher catalytic activity than Fe TCPP, was conveniently prepared and was easily recovered by simple isolation from the reaction mixture, and it was a promising catalyst in industrial applications.