不同钼锆质量比MoO3-ZrO2复合氧化物的结构及催化活性研究

采用溶胶凝胶法制备介孔MoO₃-ZrO₂复合氧化物,考察MoO₃/ZrO₂的质量比对其晶相结构、比表面积、孔径以及形貌特征的影响。利用XRD、N₂吸附-脱附、SEM及FT-IR表征对所制得的复合氧化物进行分析。以FCC汽油馏分为原料,对MoO₃-ZrO₂经预硫化后制得的催化剂进行加氢脱硫评价。结果表明,含有MoO₃的ZrO₂与不含MoO₃的ZrO₂相比单斜相减少,主要以稳定的四方相存在。适当的提高MoO₃/ZrO₂的质量比有利于MoO₃-ZrO₂复合氧化物的比表面积和平均孔径的增大,但过大的质量比并不利于介孔的生长,并且有新的化合键和少量Zr(MoO₄)₂相产生。当MoO₃/ZrO₂的质量比为30%时,ZrO₂表面出现蠕虫状结构,此时脱硫率最高。由此,适当提高MoO₃/ZrO₂质量比可使催化剂的脱硫率升高。

Study on the structure and performance of MoO3-ZrO2 composite catalysts with different Mo/Zr mass ratios

Mesoporous MoO₃-ZrO₂ composite oxides were prepared by sol-gel method. The influence of the mass ratio of MoO₃/ZrO₂ on the crystal phase, specific surface area, pore size and morphology characteristics were investigated. The synthesized composite oxides were characterized by XRD, BET, SEM and FT-IR. With FCC gasoline fraction as the raw material, the catalytic activity was evaluated by hydrodesulfurization reaction after the prevulcanization of the composite oxides. The results show that the ZrO₂ containing MoO₃ had less monoclinic phase than ZrO₂ and mainly existed in stable tetragonal phase. The appropriate improvement of the mass ratio of MoO₃/ZrO₂ were beneficial to the increase of specific surface area and average pore size. The excessive mass ratio of MoO₃/ZrO₂ depressed the formation of mesopores and produced a new type chemical bond and a small amount of Zr(MoO₄)₂ crystal phase. When the mass ratio of MoO₃/ZrO₂ was 30%, the worm structure appeared on the surface of ZrO₂, and the desulfurization rate reached its maximum. Thus, the appropriate improvement of the mass ratio of MoO₃/ZrO₂ could obtain a higher desulfurization rate.