Metathesis of Butylene-2 and Ethylene to Propylene over 3.0Mo／（Hβ＋γ-Al2O3） Catalysts with Different γ-Al2O3 Contents

A series of 3. OMo/(Hβ γ-Al2O3) samples with γ-Al2O3 contents in the range of 0-100% (mass fraction) was studied by means of XRD, NH3-TPD, TPR and BET determinations for characterizing their structures. The Hβ zeolite structure in the 3.0Mo/Hβ sample can be effectively stabilized by adding some γ-Al2O3 to Hβ zeolite. γ-Al2O3 mainly favors the formation of polymolybdate or multilayered Mo oxide, while Hβ mainly forms the Al2(MoO4)3 species, as evaluated by the TPR technique. When used as the catalyst for the metathesis of butylene-2 and ethylene to propylene, there exists a close correlation between the specific surface area and stability of the catalyst. The specific surface area of the catalyst shows the maximum when (Hβ γ-Al2O3) contains 30%γ-Al2O3, which is in agreement with that of the time needed for the reaction stablization. In the case of maximum surface area, the rate of coke deposition is the minimum.