Activated carbon supported nitrogen-containing diheterocycle mercury-free catalyst for acetylene hydrochlorination

An original nonmetallic mercury-free catalyst for the production of vinyl chloride monomer (VCM) by acetylene hydrochlorination was studied in this work. It was first found that a nitrogen-containing diheterocycle, 1,8-diazabicyclo[5.4.0]undec-7-ene hydrochloride ([DBU][Cl]), displayed excellent catalytic performance in acetylene hydrochlorination. The 20%[DBU][Cl]/AC catalyst exhibited an acetylene conversion of 86.7% and a selectivity to VCM of 99.2%, and the deactivation rate was only 0.033 %/h during the 200 h lifetime evaluation under the conditions of a bed temperature of 240 °C, GHSV(C 2 H 2 ) of 30 h −1 and V(HCl)/V(C 2 H 2 ) of 1.2. TPD characterizations and intermittent flow experiments revealed that the 20%[DBU][Cl]/AC catalyst has a larger HCl adsorption capacity and smaller VCM adsorption capacity, which may be one of the reasons for the good catalytic activity and stability. The catalytic mechanism over [DBU][Cl] was proposed based on DFT calculations.