Mechanism exploring of acetylene hydrochlorination using hexamethylenetetramine as a single active site metal-free catalyst

An activated carbon (AC) supported hexamethylenetetramine (HMT), with a single tertiary amine N active site, was proposed to be used as a novel metal-free catalyst for acetylene hydrochlorination reaction. The 25% HMT/AC catalyst provided acetylene conversion of similar to 60% and C2H3Cl selectivity above 99% at 220 degrees C with a gas hourly space velocity (GHSV) of 30 h(-1). X-ray photoelectron spectra suggested the tertiary amine nitrogen was the only N species in the catalysts. Theoretical calculations and experimental studies showed that HCl is adsorbed by HMT preferentially. The insertion of acetylene into Cl-H bond of HCl is the key step.