Gas-Phase Catalytic Hydrochlorination of Acetylene in a Two-Stage Fluidized-Bed Reactor

Production of vinyl chloride monomer (VCM) by the hydrochlorination of acetylene with HCl was investigated in both a single-stage fluidized bed (SSFB) and a two-stage fluidized bed (TSFB) at different reaction temperatures and space velocities of acetylene. The conversion of acetylene increases with increasing temperature and decreases with increasing space velocity. Over a wide range of operating conditions, a higher conversion of acetylene was achieved in the TSFB than in the SSFB, with the selectivity of VCM being almost 100%. This process can be described by a two-dimensional dispersion and reaction model. A new catalyst, HgCl 2 supported on a coconut-shell-type activated carbon, which has a much higher mechanical strength than the industrial catalyst (HgCl 2 supported on a coal-based activated carbon), was employed in the fluidized beds. Evaluation of the catalyst lifetime in a fast sublimation experiment at high temperature showed that the new catalyst has a longer lifetime than the industrial catalyst. The novel TSFB technology, combined with the new catalyst, is effective in providing a higher throughput and quality of the VCM product than the conventional PB reactor.