La_2O_3协同增强SAPO-34的二甲醚制烯烃催化性能  

La_2O_3 synergetic effect to improve catalytic performance of SAPO-34 molecular sieve used for dimethyl ether to olefins reaction

作　　者：曹迎倩 高玉李[1] 陈胜利[1] 袁桂梅[1] 王涯 朱茹月 陈楠 

机构地区：[1]中国石油大学(北京)重质油国家重点实验室,北京102249

出　　处：《化工学报》2017年第12期4607-4614,共8页CIESC Journal

基　　金：国家自然科学基金项目(91534120)~~

摘　　要：La_2O_3不需要与SAPO-34接触,便可显著延长SAPO-34的二甲醚制烯烃(DTO)反应寿命,并且La_2O_3与SAPO-34比例越大,SAPO-34的反应寿命越长。当La_2O_3和SAPO-34的质量比为1:1时,SAPO-34寿命提高了约1倍。进一步的研究表明,只有当La_2O_3层夹在SAPO-34层中间时,才能提高SAPO-34的寿命,La_2O_3无论是处于SAPO-34上游还是下游,均不能提高SAPO-34的寿命。动力学和催化剂的积炭量研究表明,La_2O_3是通过降低SAPO-34的积炭速度提高其反应寿命的。初步提出了La_2O_3提高SAPO-34寿命的机理:在DTO反应过程中,二甲醚在SAPO-34分子筛上形成一种积炭前体,这种积炭前体转移到La_2O_3的表面上,反应生成不能积炭的化合物(CO、CO2和H2等),从而降低了SAPO-34的积炭失活速度,提高了其寿命。The working lifetime of SAPO-34 for dimethyl ether to olefins（DTO） reaction was increased by non-contact La2O3. Increasing ratio of La2O3 to SAPO-34 prolonged working lifetime of SAPO-34. When the mass ratio of La2O3 to SAPO-34 was 1：1, the working lifetime of SAPO-34 was almost twice as much as that of SAPO-34 alone. La2O3 sandwiched in SAPO-34 had improvement, whereas La2O3 in upstream and downstream of SAPO-34 did not. Reaction kinetics and coke amount on SAPO-34 indicated that La2O3 decreased coking rate of SAPO-34. A synergetic mechanism for SAPO-34 and La2O3 was proposed that a coke precursor created on SAPO-34 during DTO was converted to non-coke forming species（such as CO, CO2 and H2） upon traveling onto La2O3 surface such that SAPO-34 coking rate was decreased and its working lifetime was increased.

关 键 词：SAPO-34 分子筛 混合 失活 二甲醚制烯烃 甲醇制烯烃 协同作用 

分 类 号：O643[理学—物理化学]