Multi-component Composite Non-precious Metal Mercury-free Catalyst For Acetylene Hydrochlorination

Vinyl chloride?VCM?is the raw material for the synthesis of polyvinyl chloride?PVC?.In China,vinyl chloride was prepared by hydrochlorination of acetylene wit-h mercuric chloride as catalyst.Due to the increasingly depletion of mercury resour-ces and the serious environmental pollution caused by the use of mercury,research-ers began to develop environmentally friendly mercury-free catalysts to replace mer-curic chloride.At the beginning of the study,the precious metal catalyst represente-d by Au is the main one,which has good conversion,selectivity and stability at t-he beginning of the catalysis,but it is difficult to be used in actual production due to its high cost.Mercury-free non-noble metal catalysts have been studied for many years,among which three-component catalysts are the main ones.The results show that the three-component catalyst has the drawbacks of short life,poor stability and poor catalytic performance.In this paper,mercury-free non-noble metal catalysts wit-h four-component and trace transition metal element Fe were studied and their app-lications in the hydrochlorination of acetylene was investigated.In this paper,a series of catalysts were prepared with high valence tin and co-pper as the main active components.The effects of different pre-treatment of the su pport on the performance of the catalyst were investigated.The differences of the a-ctivity between the high component and the single or double component non-noble metal mercury-free catalysts were compared.The changes of the activity of the hig-h valence tin copper mercury-free catalyst with different alkaline earth metals as th-e secondary active components were discussed.The effects of the addition of BiCl₃,CeCl₃and trace transition metal element Fe on the high valence tin copper catalyst were investigated;In order to confirm whether the trace transition metal element Fe has synergistic effect with the active components,a comparative experiment was ad-ded;the material ratio between the active components was optimized by the orthog-onal method,and the process conditions were optimized.At the same time,the anti-interference experiment was carried out to investigate the stability of the non-noble metal high component mercury-free catalyst.The research results are as follows:?1?After pretreatment,the catalytic performance of activated carbon carrier was improved significantly.The results show that the catalytic performance of the treate-d coal-based activated carbon is significantly improved.The catalytic performance o-f coconut shell activated carbon is similar to that of washed coal activated carbon.The effect of water washing or acid catalysis on coal based activated carbon has lit tle change.?2?The increase of the component of non-noble metal mercury-free catalyst ca-n improve the catalytic performance,and the multi active components show synergi stic effect.The multi-component catalyst has better stability and longer life than the single and two-component catalyst.?3?The addition of cerium to the multi-component non-noble metal mercury-fre e catalyst makes the catalyst more stable,reduces the loss of active components an-d improves the conversion of acetylene.?4?The optimal ratio of SnCl₄-CuCl₂-BiCl₃-CeCl₃-FeCl₃/C composite mercury-fr ee catalyst is 2%SnCl₄/10%CuCl₂/1.5%BiCl₃/1.5%CeCl₃/0.15g FeCl₃.The results s-how that the most suitable conditions for catalyst reaction are:activation time 1 h,r-eaction temperature 140?,space velocity 90 H^-1,material ratio V?HCl?/V?C₂H₂?=1.05.Under the above conditions,the initial catalytic activity of the multi-component com-posite mercury-free catalyst is close to that of the mercury catalyst,and it has good stability and strong anti-interference ability.The conversion of acetylene is 95.2%,a-nd the selectivity of vinyl chloride is 99.5%.