Influence of oxygen-containing groups of activated carbon aerogels on copper/activated carbon aerogels catalyst and synthesis of dimethyl carbonate

Abstract

Active catalysts that were prepared by dispersing copper (Cu) nanoparticles on potassium hydroxide (KOH)-activated carbon aerogels (ACAs) were investigated in the synthesis of dimethyl carbonate (DMC) by vapor-phase oxidative carbonylation of methanol. The effect of mesopores and surface oxygen-containing groups (OCGs) including C = O, COOH and OH of the ACAs on the dispersion of active species and catalytic properties was determined. An increase in molar ratio of resorcinol to anhydrous sodium carbonate (R/C) lead to the creation of mesopores within the original carbon aerogels (CAs), which benefits to molecules mass transport. The amount of surface OCGs increased positively with KOH/CAs mass ratio, which affected the valence distribution of Cu species, improved the Cu dispersion and enhanced the catalytic activity. For an optimum R/C of 500 and a KOH/CAs mass ratio of 4, the Cu/ACAs catalyst maintains a prominent DMC space time yield of 338.7 mg/(g h) and a methanol conversion of 2.5%. Density functional theory calculations indicate that of the different surface OCGs of the carbon support, enrichment in C = O group enhances the interaction between the metal and the ACAs support significantly and contributes to the formation of the smallest Cu nanoparticles and the highest catalytic activity.