摘要
采用等量浸渍法制得一系列不同担载量的Mo/HZSM - 5催化剂 ,运用XRD和FTIR方法考察了Mo物种在催化剂表面的分散状态 ,首次采用微分吸附量热技术对Mo/HZSM - 5催化剂的表面酸性进行表征。同时研究了催化剂对丙烷芳构化的反应活性。结果表明 :对于担载Mo的HZSM - 5分子筛催化剂 ,Mo物种在HZSM - 5分子筛表面上的分散作用 ,覆盖了HZSM - 5分子筛本身表面的酸性位 ,导致Mo/HZSM - 5催化剂表面酸性的降低 ,酸性强度减少的顺序为HZSM - 5 >1 %Mo/HZSM - 5 >2 %Mo/HZSM - 5 >5 %Mo/HZSM - 5。在Mo/HZSM - 5催化剂中 ,定位在HZSM - 5分子筛孔道内处于高分散状态的钼物种 ,中等大小的HZSM - 5分子筛孔结构和适当强度数量的酸中心 ,有利于芳构化产物的生成。催化剂的反应活性大小顺序为 2 %Mo/HZSM - 5 >1 %Mo/HZSM - 5 >5 %Mo/HZSM - 5。即当酸性和Mo担载量均处于适当值的时候 。
A series of Mo/HZSM-5 catalysts were prepared by incipient wetness impregnation method with various of Mo loadings The dispersion of Mo species on catalysts surface was investigated by XRD and FTIR The surface acidity property of Mo/HZSM-5 catalysts was characterized by microcalorimetry adsorption technique first time, and the activity of propane aromatization reaction over those catalysts was also studied It was found that when the HZSM-5 catalysts modified by Mo was used, Mo species dispersed on the HZSM-5 surface covered the stronger acid sites of HZSM-5 zeolite surface to decrease the surface acidity The order of acid strength decrease is HZSM-5>1%Mo/HZSM-5>2%Mo/HZSM-5>5%Mo/HZSM-5 It is favorable to the formation of propane aromatization product that Mo species disperse highly on the HZSM-5 surface in HZSM-5 aperture structure with the appropriate strength acid sites The activity order of catalysts is 2%Mo/HZSM-5>1%Mo/HZSM-5>5%Mo/HZSM-5 It is found that only when both of the acidity and the Mo loading of catalysts are appropriate, the catalytic activity of the Mo/HZSN-5 catalysts can be optimum
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2000年第1期20-23,共4页
Journal of Fuel Chemistry and Technology
基金
国家自然科学基金!( 2 9973 0 1 3 )
科技部资助项目
关键词
催化剂
吸附量热
丙烷芳
构化
催化
Mo/HZSM-5 catalysts, microcalorimetry adsorption, propane aromatization reaction
