Density-functional theory study on hydrogenation of dimethyl oxalate to methyl glycolate over copper catalyst: Effect of copper valence state

Alkaline earth modified activated carbon supported Cu catalysts with enhanced selectivity in the hydrogenation of dimethyl oxalate to methyl glycolate

In this work, the effect of alkaline earth metal modification on the catalytic performance of activated carbon supported Cu was investigated. The experimental results showed that the introduction of Ca and Sr improved the selectivity of methyl glycolate (MG) during hydrogenation of dimethyl oxalate (DMO) in gas phase. The optimal loading amount of Ca was 0.1 wt%, and under the optimal conditions (temperature 240 °C, pressure 2 MPa, hydrogen-ester ratio of 80, feedstock 15% DMO methanol solution, and WLHSVDMO = 0.9 h-1) the selectivity of MG was as high as 94%, and the conversion of DMO was 97%. The optimal loading of Sr was 0.2 wt% with MG selectivity up to 89% and DMO conversion of 98%. The results of catalyst characterization showed that both Ca and Sr modifications were beneficial to further reduce the particle size of Cu, improve the dispersion of Cu, increase the basicity of the catalyst, and improve the stable presence of Cu+ during the reaction process. Cu+ was beneficial to the stabilization of the MG species, in which Cu+ accounted for more in the Ca-modified catalysts Cu+/(Cu+ + Cu0) = 0.65, and in the Sr-modified ones Cu+/(Cu+ + Cu0) = 0.51. Therefore, both Ca and Sr modified catalysts showed improvement in the selectivity of MG.

Selective Hydrogenation of Dimethyl Oxalate to Methyl Glycolate over Boron-Modified Ag/SiO2 Catalysts

The addition of boron (B) as a promoter to the Ag/SiO₂ catalyst for the selective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) was investigated. A comparison of the preparation method for incorporation of B found that the addition during the ammonia evaporation deposition-precipitation synthesis of the Ag/SiO₂ catalyst (Ag-B/SiO₂) was inferior to incipient wetness impregnation introduction of the Ag/SiO₂ catalyst (B/Ag/SiO₂). Moreover, the effects of B contents (0.5-5 wt %) on the physicochemical properties and catalytic performance of the B/Ag/SiO₂ catalysts were investigated by XRF, N₂-physisorption, XRD, FTIR, TEM, EDX mapping, H₂-TPR, NH₃-TPD, XPS, and catalytic testing. The results indicated that both the catalytic activity and stability of the Ag/SiO₂ catalyst were noticeably enhanced after the introduction of B. The B/Ag/SiO₂ catalyst with 1 wt % B showed the best catalytic performance of 100% DMO conversion and 88.3% MG selectivity, which could be attributed to the highest dispersion of the active metal and the smallest Ag particle size stabilized by the strong interaction between silver and boron species.

Ni-Modified Ag/SiO2 Catalysts for Selective Hydrogenation of Dimethyl Oxalate to Methyl Glycolate

Ni-modified Ag/SiO₂ catalysts containing 0~3 wt.% Ni were obtained by impregnating Ni species onto Ag/SiO₂ followed by calcination and reduction. The catalysts’ performance in the hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) was tested. Ag-0.5%Ni/SiO₂ showed the highest catalytic activity among these catalysts and exhibited excellent catalytic stability. The effects of the Ni content on the structure and surface chemical states of catalysts were investigated by XRF, N₂-sorption, XRD, TEM, EDX-mapping, FT-IR, H₂-TPR, UV–vis, and XPS. The better catalytic activity and stability of Ni-modified Ag/SiO₂ (versus Ag/SiO₂) are ascribed to the improved dispersion of active Ag species as well as the higher resistance to the growth of Ag particles due to the presence of Ni species.

Computer-aided bimetallic catalyst screening for ester selective hydrogenation

Bimetallic catalyst screening for ester selective hydrogenation has been performed by combining microkinetic analysis and machine learning methods.

A DFT and microkinetic study of propylene oxide selectivity over copper-based catalysts: effects of copper valence states

The development of high-performance copper-based catalysts is critical for the selective oxidation of propylene in both technology and scientific fields.