CuCl2 promoted low-gold-content Au/C catalyst for acetylene hydrochlorination prepared by ultrasonic-assisted impregnation

•The interaction between Au and Cu atoms increases the reduction activation energy of Au3+ → Au0.•The addition of 4 wt% Cu to Au/C increases the catalytic activity and the Au loading is decreased to 0.25 wt%.•Au(0.25%)Cu(4%)/C exhibits more Au3+ species than Au(0.25%)/C catalyst.

A detailed study of low-gold-content Au(0.25%)/C and Au(0.25%)Cu(4%)/C catalysts prepared via ultrasonic-assisted impregnation method is described and discussed. The addition of 4 wt% Cu to Au/C increases the initial activity and the Au loading is decreased to 0.25 wt%. Au(0.25%)Cu(4%)/C exhibits best catalytic performance with an acetylene conversion of 97.4% and the selectivity to VCM of more than 99% at a space velocity of 720 h−1 and 150 °C. The observations are rationalized in terms: (i) Au(0.25%)Cu(4%)/C exhibits relative larger specific surface area (562 m2/g) than Cu(4%)/C (385 m2/g), which provides more active sites for acetylene hydrochlorination; (ii) the reduction activation energy of Au3+ → Au0 in Au(0.25%)Cu(4%)/C (45.5 kJ/mol) is much higher than that of Au(0.25%)/C (35.6 kJ/mol), which indicates that the Au3+ species in Au(0.25%)Cu(4%)/C catalyst is more difficult to be reduced, the reduction activation energy of Cu+ → Cu0 in Au(0.25%)Cu(4%)/C (48.9 kJ/mol) is higher than that of Cu(4%)/C (43.1 kJ/mol) as a result of the electronic interaction between Au and Cu atoms; (iii) Au(0.25%)Cu(4%)/C possesses more Au3+ species (28%) than Au(0.25%)/C (16%) determined by XPS. Free-mercury low-gold-content Au(0.25%)Cu(4%)/C catalyst is environmental-friendly, making it a potentially green catalyst for acetylene hydrochlorination.

Graphical abstractA low-gold-content Au(0.25%)Cu(4%)/C catalyst was prepared via ultrasonic-assisted impregnation method for the first time and applied to acetylene hydrochlorination. Figure Catalytic performance of Au(0.25%)Cu(4%)/C and the deduced reaction mechanism for acetylene hydrochlorination over Au(0.25%)Cu(4%)/C catalyst.Figure optionsDownload full-size imageDownload as PowerPoint slide