Study on quantitative structure of coke deposition in UDH catalyst for acetylene hydrochlorination

The catalyst made of Au, Cu and K according to a certain ratio which is defined as a UDH catalyst has a great catalytic effect on acetylene hydrochlorination. In order to clarify the formation mechanism of coke deposition in catalyst, the structure of coke deposition was quantified. Carbon deposits in the UDH catalyst are separated using Soxhlet extraction and rotary evaporation. Experimental techniques like gel chromatography, elemental analysis, H-NMR and FT-IR were applied for the characterization of coke deposition. The quantitative structure of the coke deposition was evaluated by the improved B-L method. The results show that the average molecular formula of the coke deposition is C40.82H33Cl15.55 which is a complex multiple-ring structure containing seven aromatic rings and five six-membered cycloalkane rings. The aromatic carbon fraction of the calculated coke deposition is 0.623, and the ratio of hydrogen to carbon atomic which are not replaced in aromatic ring moieties is 0.313. These results indicate that in the side reaction of acetylene hydrochlorination, substances with the ring structure are more likely to be generated, and the ring structure continues to increase, eventually forming coke deposition.