Effects of space velocity, reaction temperature and support acidity on product distribution and induction period in 1-butene isomerization and metathesis over Mo/mordenite-alumina were investigated. As revealed by the catalytic performance results, induction period and objective product were closely related to the reaction conditions. Lower space velocity led to longer induction period and higher propene yield. The optimal reaction temperature for propene production is around 150C and it shifted to 100C for ethene production. 1-Butene auto-metathesis predominated in the reaction network if the support with lower degree of sodium exchanged. And propene gradually became the dominant product upon increasing the support sodium exchange degree. 6Mo/H 100 Na 0 M-30Al catalyst with a support of full sodium exchange degree exhibited the highest propene yield.
A series of 3.0Mo/MCM-22-Al2O3 catalysts with γ-Al2O3 contents in the range of 0-100 wt%were prepared and applied in the metathesis reaction of ethene and butene-2.Addition of γ-Al2O3 did not affect the structure of MCM-22 zeolite as evidenced by XRD and N2 adsorption measurements.It was deduced from TPR experiments that γ-Al2O3 phase favored the formation of polymolybdate or multilayered Mo oxide,while more Al2(MoO4)3 species were generated over MCM-22 zeolites.Alumina content in the support was directly related to the metathesis activity of ethene and butene-2 to propene.Mo species with higher valence(Mo6+or Mo5+)contributed more to the excellent performance of catalyst than metallic Mo.The best catalyst activity and stability was obtained over 3.0Mo/(MCM-22-30%Al2O3)under the reaction condition of 1.0 MPa and 125℃ using N2 as the pretreatment gas.
