催化学报

催化学报 ›› 2008, Vol. 29 ›› Issue (9): 913-920.

• 研究论文 • 上一篇    下一篇

Co/Pd催化剂上CH4/CO2等温两步反应直接合成乙酸的热力学

章日光,黄伟,王宝俊   

  1. 太原理工大学煤科学与技术教育部和山西省重点实验室, 山西太原 030024
  • 收稿日期:2008-09-25 出版日期:2008-09-25 发布日期:2012-07-19

Thermodynamics of Direct Synthesis of Acetic Acid from CH4 and CO2 by a Two-Step Isothermal Reaction Sequence on Co/Pd Catalysts

ZHANG Riguang, HUANG Wei*, WANG Baojun   

  1. Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
  • Received:2008-09-25 Online:2008-09-25 Published:2012-07-19

PDF

1114

被引次数

26

摘要： 采用量子化学密度泛函理论对CH4/CO2两步法合成乙酸反应中表面碳化物CHx (x=0～3)在Co和Pd模型表面上不同吸附活性位上的吸附能、空间构型和反应吉布斯自由能进行了系统性的比较研究. 计算结果表明, CH4/CO2两步反应在单一金属Co或Pd催化剂上在常压等温条件下不能有效进行,但在Co和Pd组成的双金属催化剂上,两步反应在常压等温下可以进行. 在Co和Pd双金属催化剂上,金属Co活化CH4生成金属碳化物CHxCo(x=0, 1)为热力学允许反应,其后CHx溢流到金属Pd上形成CHyPd (y=1～3)碳化物,最后CO2插入CHyPd生成乙酸,后两者在常压等温情况下也为热力学允许反应,并且在435 K以上可以与前者构成等温循环. 计算结果与实验结果吻合.

关键词: 表面碳物种, 钯, 热力学, 机理, 密度泛函理论, 甲烷, 二氧化碳, 乙酸

Abstract: The reaction sequence of the direct synthesis of acetic acid by CH4/CO2 two -step reaction on binary Co/Pd catalysts under isothermal conditions, which is favored in thermodynamics, goes through as follows: first, Co activates CH4 le ading to CHxCo (x=0,1); then， the overfall of CHx f r om Co to Pd generating CHyPd (y=1-3); last, CO 2 inserts into CHyPd forming acetic acid.

Key words: carbon species, cobalt, palladium, thermodynamics, mechanism, density functional theory, methane, carbon dioxide, acetic acid