不同氧化物对WO_(3)/SiO_(2)催化烯烃异构-歧化串联反应的影响

Effect of Different Oxides on Olefin Isomerization-Metathesis Catalyzed by WO_(3)/SiO_(2) Catalyst

为了提高烯烃歧化催化剂的性能,以WO 3/SiO 2为研究对象,研究了不同氧化物(MgO、CaO、BaO、SiO 2)对其催化性能的影响。首先比较了各种氧化物对1-丁烯异构反应的作用强弱,之后考察了不同氧化物与WO 3/SiO 2催化剂混合装填对1-丁烯自歧化反应的影响。结果表明:不同氧化物的异构活性由大到小的顺序为CaO、BaO、MgO、SiO 2;掺混MgO与SiO 2可以使反应体系稳定性更强;而与SiO 2相比,MgO更好地促进了交叉歧化反应,使丙烯的选择性提高。最后研究了MgO掺混量对乙烯和顺-2-丁烯歧化制丙烯反应的影响,发现MgO的最佳掺混质量分数为30%。

Currently,WO 3/SiO 2 catalyst is the only industrialized olefin metathesis catalyst due to its low cost and strong anti-toxicity,but it needs to mix with promoters to maintain the high activity and stability.In order to improve this process,the effects of different oxides(MgO,CaO,BaO,SiO 2)on the catalytic performance of WO 3/SiO 2 catalyst were investigated.The effects of oxides on 1-butene isomerization were tested firstly,with a descending order of CaO,BaO,MgO,SiO 2.The self-metathesis of 1-butene was then studied under the catalysis of WO 3/SiO 2 mixed with different oxides,in which MgO and SiO 2 can make the reaction more stable.While the propylene selectivity in the MgO system was higher than that in SiO 2 system,due to the accelerated cross-metathesis between 1-butene and 2-butene,which generates from the isomerization of 1-butene over MgO.Finally,the effects of different loading mass fraction of MgO in the metathesis of ethylene and cis-2-butene was studied.Results show that the optimum loading mass fraction of MgO is 30%.