不同钼锆质量比MoO_3-ZrO_2复合氧化物的结构及催化活性研究

Study on the structure and performance of MoO_3-ZrO_2 composite catalysts w ith different Mo/Zr ratios

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。

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,SEMand FT-IR. With FCC gasoline fraction as the rawmaterial,the catalytic activity was evaluated by hydrodesulfurization reaction after the prevulcanization of the composite oxides. The results showthat 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 newtype chemical bond and a small amount of Zr（MoO4）2crystal 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.