A series of 3.0Mo/(Hβ+γ-Al_2O_3) samples with γ-Al_2O_3 contents in the range of 0_100%(mass fraction) was studied by means of XRD, NH_3-TPD, TPR and BET determinations for characterizing their structures. The Hβ ...A series of 3.0Mo/(Hβ+γ-Al_2O_3) samples with γ-Al_2O_3 contents in the range of 0_100%(mass fraction) was studied by means of XRD, NH_3-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-Al_2O_3 to Hβ zeolite. γ-Al_2O_3 mainly favors the formation of polymolybdate or multilayered Mo oxide, while Hβ mainly forms the Al_2(MoO_4)_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-Al_2O_3) contains 30%γ-Al_2O_3, 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.展开更多
文摘A series of 3.0Mo/(Hβ+γ-Al_2O_3) samples with γ-Al_2O_3 contents in the range of 0_100%(mass fraction) was studied by means of XRD, NH_3-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-Al_2O_3 to Hβ zeolite. γ-Al_2O_3 mainly favors the formation of polymolybdate or multilayered Mo oxide, while Hβ mainly forms the Al_2(MoO_4)_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-Al_2O_3) contains 30%γ-Al_2O_3, 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.
