Hydrogenolysis of Dimethyl Maleate on Cu/ZnO/Al2O3 Catalysts

New insight into the catalytic mechanism of ester hydrogenation over the Cu/ZnO catalyst: the contribution of hydrogen spillover

The dimethyl maleate hydrogenation activity of Cu, ZnO-X and physically mixed Cu+ZnO-X samples was systematically investigated to probe the essential role of ZnO in ester hydrogenation processes. Cu samples exhibited high CC bond hydrogenation ability with dimethyl succinate as the main product. Comparatively, ZnO was inactive in hydrogenation due to its weak ability to dissociate hydrogen while the CO group could be activated and adsorbed on the ZnO surface. Interestingly, physical mixing with ZnO significantly improved the CO hydrogenation activity of Cu samples. The H2-TPD results reveal the origin of "Cu-ZnO synergy": hydrogen atoms formed on the copper surface can spill over to the ZnO surface and react with the adsorbed CO group.

Efficient and Eco-Friendly Perspectives for C-H Arylation of Benzothiazole Utilizing Pd Nanoparticle-Decorated Chitosan

In this contribution, an eco-friendly, sustainable, and efficient palladium nanoparticle-decorated chitosan (Pd@Chitosan) catalyst was synthesized by a simple impregnation method. The synthesized material was utilized as a heterogeneous catalyst for the C-H arylation of benzothiazole under ultrasonic irradiation. The Pd@Chitosan catalyst efficiently catalyzed the conversion of aryl iodides and bromides to 1-(4-(benzothiazol-2-yl)phenyl)ethan-1-one selectively. A single product of 83–93% yield was obtained in N,N-dimethylformamide solvent at 80 °C for 2.5h. This study reveals that Pd@Chitosan is an efficient catalyst, which catalyzes the C-H arylation with good reaction yields. The activity of the Pd@Chitosan is due to the presence of highly dispersed Pd(0) nanoparticles on the surface of the chitosan and Pd2+; a tentative mechanism was proposed based on the XPS results of the fresh catalyst and spent catalyst.

Recent progress in hydrogenation of esters on heterogeneous bimetallic catalysts

The development and research of highly effective heterogeneous catalysts for the hydrogenation of esters, providing high activity and selectivity of the formation of the corresponding alcohols, is an urgent task of modern heterogeneous catalysis.

Recent progress in improving the stability of copper-based catalysts for hydrogenation of carbon–oxygen bonds

Five different strategies to enhance the stability of Cu-based catalysts for hydrogenation of C–O bonds are summarized in this review.

Hydrogenation of dimethyl malonate to 1,3-propanediol catalyzed by a Cu/SiO2 catalyst: the reaction network and the effect of Cu+/Cu0 on selectivity

1,3-Propanediol was synthesized via the hydrogenation of dimethyl malonate over a Cu/SiO₂ catalyst. The reaction network and active sites were revealed for the first time.

Dynamic redox cycle of Cu0 and Cu+ over Cu/SiO2 catalyst in ester hydrogenation

Esters can oxidize Cu⁰ to Cu⁺ and the obtained Cu⁺ can be reduced back to Cu⁰ by H₂ under reaction conditions. Cu⁰ and Cu⁺ are in a dynamic cycle during ester hydrogenation.