Effect of Different Nano-Sized Silica Sols as Supports on the Structure and Properties of Cu/SiO2 for Hydrogenation of Dimethyl Oxalate

Abstract

Cu/x-SiO 2 catalysts with 4, 10, and 20 nm silica sols as supports was produced by ammonia evaporation method and characterized. Different nano-sized silica sols as supports significantly affected the structure and catalytic properties of the copper catalysts for ethylene glycol synthesis from dimethyl oxalate. Compared with Cu/20-SiO 2 and Cu/4-SiO 2 catalysts, the catalytic performance and stability of Cu/10-SiO 2 catalyst were greatly enhanced. The Cu/10-SiO 2 catalyst showed 99.9% conversion with 94% EG selectivity and a lifetime of over 3080 h if it is calculated by industrial weight liquid hourly space velocity (WLHSV) of 0.5 h −1 . The Cu/10-SiO 2 catalyst has one of the longest lifetimes among the catalysts and is a good alternative catalyst for this reaction. Improvement in the catalytic performance and stability of Cu/10-SiO 2 is attributed to the proper S BET , D p and larger dispersion of copper. In addition, the supports of Cu/10-SiO 2 catalyst have smaller particles than that of Cu/20-SiO 2 ; thus, the migration and growth of copper species in catalysts are restrained during the reaction.

Perspectives on the Active Sites and Catalyst Design for the Hydrogenation of Dimethyl Oxalate

“…However, its potential in industrial applications was limited by its poor stability (<100 h), which was caused by the aggregation of Cu NPs, carbon deposition, and the loss of silica via the formation of tetramethoxysilane with methanol. , To enhance the long-term properties of Cu-SiO 2 based catalysts, several methods have been introduced in the literature. Using nanosized silica sols to regulate Cu NP size and dispersion. For instance, silica sols 10 nm in size have been demonstrated to be capable of restraining the migration and growth of copper species Confining Cu NPs in phyllosilicate nanotubes by a hydrothermal method. ,, Using ordered mesoporous SiO 2 (OMS) as the support for Cu NPs.…”

“…Using nanosized silica sols to regulate Cu NP size and dispersion. For instance, silica sols 10 nm in size have been demonstrated to be capable of restraining the migration and growth of copper species …”

“…For instance, silica sols 10 nm in size have been demonstrated to be capable of restraining the migration and growth of copper species. 104 (2) Confining Cu NPs in phyllosilicate nanotubes by a hydrothermal method. 69,86,87 (3) Using ordered mesoporous SiO 2 (OMS) as the support for Cu NPs.…”

“…As catalysts need to be prepared on a large scale for DMO hydrogenation in industry, a deep understanding of the steps involved in the catalyst preparation method, particularly in the ammonia-evaporation method, is mandatory to understand the structure of the material and to design nextgeneration catalysts for DMO hydrogenation. For the catalysts synthesized by the ammonia-evaporation method, the effects of the raw materials (e.g., different nanosized silica sols), 104 evaporation temperature, 17 calcination temperature, 157 hydrothermal procedure, 158 and the ratio between ammonia and copper on the structure and performance of the catalysts have been well studied. 159 However, two main challenges for the ammonia-evaporation method, namely the filtered copper species and the large volume of evaporated ammonia, need to be solved in industrial preparations.…”

Preparation of Highly Active Cu/SiO2 Catalysts for Furfural to 2-Methylfuran by Ammonia Evaporation Method

“…It is reported that Cu has a good hydrogenation ability of C-O bonds, while it does not favor the hydrogenolysis of C-C bonds [13,14], thus showing good catalytic activity in the hydrodeoxygenation of FFA. Copper-chromium catalysts are commonly used in the hydrogenation of aldehydes, ketones or esters [15][16][17][18][19]. Adkins et al [20] found that the earliest copper-chromium catalyst, Cu 2 Cr 2 O 5 , could be utilized in catalytic hydrogenation.…”