The Catalytic Properties Of MCM-22 And β Molecular Sieve In The Reaction Of Benzene With Propene

The catalytic properties of MCM-22 and βzeolites in the alkylation ofbenzene with propylene, as well as the relations between catalyticproperties and acidity and textural properties of catalyst, was studiedsystematacially. A better catalyst was screened out, which has animportant meaning for promoting the industrialization of new catalyst.MCM-22 zeolite was synthesized with hexamethylenimine as template,by hydrothermal motional crystallization method. The physicochemicalproperties of MCM-22 has been characterized. The synthesis of cumenewas carried out in a fixed-bed microreactor under liquid-phase overMCM-22, the catalytic performance and the influence of reactionconditions on the distribution of products were discussed. Under thestudied conditions, MCM-22 exhibits excellent reaction stability; theselectivity of cumene increased with increasing temperature, the contentof n-propylbenzene increased and oligomers decreased; high B/P ratio isfavor to purpose product, however, the separation of products is difficult;the change of space velocity (referred to propylene) has little influence on III北 京 化 工 大 学 硕 士 论 文the selectivity of products. The acidity and textural properties ofβand MCM-22 zeolites as alsotheir catalytic properties were compared by means of FTIR spectra, TG ,N2 sorption and reaction characterization. Results show that both theacidities and pore structures have great effects on the catalytic propertiesof zeolite. MCM-22 zeolite exhibits a lower initial activity, the selectivityof cumene is lower about 3-4% thanβzeolite, but the amount ofn-propylbenzene is lower about 1-3 times thanβzeolite and the rate ofdeactivity is clearly lower thanβzeolite. As well as physicochemical properties of catalyst having relations withits catalytic properties, the composition of reactants has also some effectson the catalytic properties of catalyst. We analyzed the hydrocarbonimpurities in benzene and propylene by GC-MS and gas chromatogram,respectively. The influence of impurities in reactants on the catalyticproperties of βzeolite over the alkylation of benzene with propylene andthe removal of impurities were discussed. Results show that the contentof water in reactants as well as nitrifier and butadiene has some effects onthe activity and stability of catalyst. An absorbent was used to remove theimpurities of propylene, which can improve the stability of catalyst.