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

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 degrees C. The observations are rationalized in terms: (i) Au(0.25%)Cu(4%)/C exhibits relative larger specific surface area (562 m(2)/g) than Cu(4%)/C (385 m(2)/g), which provides more active sites for acetylene hydrochlorination; (ii) the reduction activation energy of Au3+ -> Au-0 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+ -> Cu-0 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. (C) 2016 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.