MgO-Cr2O3/Al2O3催化剂对丙烷脱氢反应的再生性能

制备了Mg改性Cr₂O₃/Al₂O₃催化剂，利用XRD,UV-Vis,XPS,H₂-TPR,NH₃-TPD,TG等方法考察了新鲜和再生后催化剂的结构与性能。实验结果表明，助剂Mg的添加有利于催化剂再生后的物相结构稳定；随再生次数的增加，催化剂孔径增大，比表面积降低，催化剂表面Cr⁶⁺含量降低，Cr⁶⁺组分逐渐不可逆还原为Cr³⁺等稳定状态；催化剂表面主要为弱酸和中强酸，随再生次数的增加，酸量减少，但酸强度增加，Cr物种价态及其与载体的相互作用影响了表面酸性进而影响了催化剂活性；新鲜催化剂催化活性略高于再生催化剂，经多次再生后催化剂性能趋于稳定，丙烷转化率稳定在30%左右，丙烯选择性在88%以上。

Regeneration performance of MgO-Cr2O3/Al2O3 catalyst for propane dehydrogenation

Mg-modified Cr₂O₃/Al₂O₃ catalyst was prepared and the structure and performance of fresh and regenerated catalysts were investigated by XRD,XPS,H₂-TPR,NH₃-TPD,UV-Vis,TG.The experimental results show that the addition of Mg boost the phase stability of Cr₂O₃/Al₂O₃ catalyst after regeneration.With the increase of regeneration times,the pore size of the catalyst gets enlarged,but the specific surface area decreases.Also,the regeneration process leads to decrease of the surface species of Cr⁶⁺,because part of Cr⁶⁺is going to gradually convert to be a stable state of Cr³⁺and the conversion is irreversible.The surface of the MgO-Cr₂O₃/Al₂O₃ catalyst is mainly distributed with weak acid and medium strong acid sites.With the cycles of regeneration increasing,the number of acid sites decrease while the acid strength gets enhanced.The valence state of Cr species and the interaction between Cr with the support Al₂O₃ affect the surface acidity and then influence the activity of the catalyst.The catalytic activity of the fresh catalyst is slightly higher than that of the regenerated catalyst.The catalytic performance of the catalyst tends to be stable after multiple regenerations.The conversion rate of propane is about 30%and the selectivity of propylene is above 88%.