MoO3-LaHY催化剂的固相反应制备及其加氢脱硫性能研究
Hydrodesulfurization performance of MoO3-LaHY catalyst prepared by solid-state reaction
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摘要: 在空气气氛中由钼酸铵和LaHY分子筛固相反应制备了MoO3-LaHY催化剂，用XRD和NH3-TPD对其进行了表征，并以二苯并噻吩/正癸烷溶液为模型反应物（二苯并噻吩的质量分数为0.6%），评价了MoO3-LaHY的加氢脱硫催化性能。结果表明，在520℃下进行固相反应制备催化剂时，4.36%的Mo物种可借助固相反应进入到分子筛的体相形成单相复合体nMoOx·LaHY，剩余的Mo物种仍以MoO3的形式分散在分子筛外表面。由于单相复合体的形成，催化剂的晶胞参数增大，酸量有所下降。硫化处理后得到的硫化态MoO3-LaHY催化剂在310℃、4.0MPa、反应空速为20h-1的条件下进行加氢脱硫时，二苯并噻吩转化率达到了86.74％。随固相反应温度的升高，所制备的催化剂中Mo物种进入LaHY体相中的量有所增大，但其硫化态催化剂的二苯并噻吩加氢脱硫活性的变化幅度并不大。Abstract: MoOx-LaHY catalysts were prepared with the mixture of (NH4)6Mo7O24·4H2O and LaHY through solid-state reaction under air atmosphere and characterized by XRD and NH3-TPD techniques; their hydrodesulfurization (HDS) performance was evaluated by using the solution of dibenzothiophene (DBT, 0.6% by mass) in decane as a model reactant. The results indicated that by using solid-state reaction at 520℃, 4.36% of Mo species is incorporated into the molecular sieve LaHY, which forms the single-phase complex nMoOx·LaHY, while the rest Mo species is dispersed on the outer surface of LaHY. As a result of forming the single-phase complex, the lattice parameters of MoOx-LaHY catalysts are enlarged and their acidity is reduced. Over the sulfided MoOx-LaHY catalysts, the conversion of DBT reaches 86.74% for the HDS under the conditions of 310℃, 4.0MPa and a space velocity 20h-1. Raising the solid-state reaction temperature may increase the content of the single-phase complex incorporated in the resultant MoOx-LaHY catalysts, but it cannot significantly enhance their HDS activity.
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