MgO-Cr_(2)O_(3)/Al_(2)O_(3)催化剂对丙烷脱氢反应的再生性能  

Regeneration performance of MgO-Cr_(2)O_(3)/Al_(2)O_(3) catalyst for propane dehydrogenation

作　　者：卢素敏[1] 宋美华 李渊[1] 赵立国 Lu Sumin;Song Meihua;Li Yuan;Zhao Liguo(College of Chemical Engineering and Technology,Tiangong University,Tianjin 300387,China;Tangshan Natural Gas Co.,Ltd.,Tangshan Hebei 063000,China)

机构地区：[1]天津工业大学化学工程与技术学院,天津300387 [2]唐山市天然气有限公司,河北唐山063000

出　　处：《石油化工》2022年第2期124-129,共6页Petrochemical Technology

基　　金：国家自然科学基金资助项目(91745116)。

摘　　要：制备了Mg改性Cr_(2)O_(3)/Al_(2)O_(3)催化剂,利用XRD,UV-Vis,XPS,H_(2)-TPR,NH_(3)-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Cr^(6+)含量降低,Cr^(6+)组分逐渐不可逆还原为Cr^(3+)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。Mg-modified Cr_(2)O_(3)/Al_(2)O_(3) catalyst was prepared and the structure and performance of fresh and regenerated catalysts were investigated by XRD,XPS,H_(2)-TPR,NH_(3)-TPD,UV-Vis,TG.The experimental results show that the addition of Mg boost the phase stability of Cr_(2)O_(3)/Al_(2)O_(3) 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 Cr^(6+),because part of Cr^(6+)is going to gradually convert to be a stable state of Cr^(3+)and the conversion is irreversible.The surface of the MgO-Cr_(2)O_(3)/Al_(2)O_(3) 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 Al_(2)O_(3) 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%.

关 键 词：丙烷脱氢 催化剂再生 铬催化剂 镁改性 

分 类 号：TQ426.83[化学工程]