李对春,邢斌,刘红艳,刘平,王宝俊,李瑞丰
LI Duichun,XING Bin,LIU Hongyan,LIU Ping,WANG Baojun,LI Ruifeng

• 1:太原理工大学化学化工学院
• 2:大同大学化学与环境工程学院
• 3:中国科学院山西煤炭化学研究所
• 4:太原理工大学煤科学与技术教育部和山西省重点实验室

摘要(Abstract)：

为明确分子筛对MTO反应的催化活性和产物选择性的影响,采用色散力矫正的密度泛函理论方法,以SAPO-34分子筛为催化剂,考察了3种不同金属Fe、Co和Ni改性的SAPO-34分子筛布朗斯特(Brnsted,B酸)酸强度的变化,并研究不同酸性的催化剂对甲醇制烯烃(MTO)反应中的低碳烯烃催化活性和选择性的影响及2者间的关联。通过计算去质子化能比较改性前、后SAPO-34分子筛的酸性强度变化,酸性强度顺序为Fe APO-34>Co APO-34>SAPO-34>Ni APO-34。通过计算MTO反应克服的反应能垒,比较低碳烯烃的催化活性和选择性,Fe、Co、Ni金属改性的SAPO-34分子筛对乙烯生成反应的催化活性顺序为Fe APO-34≈Ni APO-34>Co APO-34;对丙烯生成反应的催化活性顺序为Fe APO-34≈Co APO-34>Ni APO-34;Ni原子的引入比Fe、Co原子的引入提高了乙烯的选择性,而Fe、Co原子的引入比Ni原子的引入提高了丙烯的选择性。
In order to clarify the effect of molecular sieve on the catalytic activity and product selectivity of MTO reaction,density functional theory including dispersion correction( GGA-PBE-D2) has been employed to study the effect of acidic strength on the activity and selectivity of methanol-to-olefins( MTO) conversion over Fe,Co and Ni modified SAPO-34 zeolites.The relationship between acidic strength and catalytic activity of different Me APO-34 zeolites was discussed.The deprotonation energy was calculated to measure the acidic strength of different Me APO-34 zeolites,and the energy barrier and reaction heat of different MTO reaction steps over Me APO-34 zeolites were calculated to compare the activity and selectivity. Results show that the acidic strength order is Fe APO-34 > Co APO-34 > SAPO-34>Ni APO-34.The catalytic activity of ethylene formation is in order of Fe APO-34≈Ni APO-34>Co APO-34,and the catalytic activity order of propene formation is Fe APO-34≈Co APO-34>Ni APO-34.The introduced of Ni atoms into the SAPO-34 zeolite framework can enhance the selectivity towards ethylene compared with that of Fe and Co atoms,however,the introduced of Fe and Co atoms into the SAPO-34 zeolite framework has higher selectivity towards propene than that of Ni atom.

关键词(KeyWords)： Fe,Co和Ni金属改性;SAPO-34分子筛;MTO;密度泛函理论;Br■nsted酸强度
Fe,Co and Ni modification;SAPO-34 zeolite;MTO reaction;density functional theory;Br■nsted acidic strength

Abstract:

Keywords:

基金项目(Foundation): 山西省留学回国人员科研资助项目(2016-104)

作者(Author): 李对春,邢斌,刘红艳,刘平,王宝俊,李瑞丰
LI Duichun,XING Bin,LIU Hongyan,LIU Ping,WANG Baojun,LI Ruifeng

DOI: 10.13226/j.issn.1006-6772.18071302

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