物理化学学报 >> 2010, Vol. 26 >> Issue (11): 3017-3022.doi: 10.3866/PKU.WHXB20101118

催化和表面结构 上一篇    下一篇

甲苯歧化与烷基转移催化剂的积碳行为

蒙根, 孔德金, 祁晓岚, 许中强   

  1. 中国石油化工股份有限公司上海石油化工研究院, 上海201208
  • 收稿日期:2010-04-22 修回日期:2010-07-07 发布日期:2010-10-29
  • 通讯作者: 孔德金 E-mail:kongdj.sshy@sinopec.com
  • 基金资助:

    上海市科委科技攻关项目(08521101900)资助

Carbon Deposition on a Toluene Disproportionation and Transalkylation Catalyst

MENG Gen, KONG De-Jin, QI Xiao-Lan, XU Zhong-Qiang   

  1. Shanghai Research Institute of Petrochemical Technology, SINOPEC, Shanghai 201208, P. R. China
  • Received:2010-04-22 Revised:2010-07-07 Published:2010-10-29
  • Contact: KONG De-Jin E-mail:kongdj.sshy@sinopec.com
  • Supported by:

    The project was supported by the Scientific and Technological Project of Shanghai Science and Technology Commission, China (08521101900).

摘要:

采用热重-差热分析(TG-DTA)、X射线光电子能谱(XPS)、傅里叶变换红外(FT-IR)光谱、低温氮吸附/脱附和氨程序升温脱附(NH3-TPD)等技术对甲苯歧化与烷基转移催化剂的积碳行为进行了研究.结果表明: 硬积碳的烧碳动力学过程近似符合一级反应, 表明它是以单层分散状态存在, 其表观烧碳活化能为110 kJ·mol-1; 反应1000 h后Cat-1000催化剂的近表面主要存在三种碳物种, 其中以碳氧单键方式存在的C占C 总量的22.7%, 以碳氧双键方式存在的C 占C 总量的9.1%, 以—C—C—方式存在的C 占C 总量的68.1%, 表明形成的碳物种主要是石墨型碳; 催化剂Cat-1000 上的积碳主要是硬积碳, 占总积碳量的3/4, 其余为软积碳; 尽管反应1000 h后 催化剂的比表面积下降较多, 但酸强度基本未改变, 仍具有良好的反应活性和稳定性, 表明覆盖在催化剂活性位上的积碳较少,积碳可能更易于沉积在载体的孔道中.

 

关键词: 甲苯歧化, 烷基转移, 积碳, 催化剂, 热重-差热分析

Abstract:

The nature of carbon deposition on a toluene disproportionation and transalkylation catalyst was characterized using thermogravimetry and differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, N2 adsorption/desorption and NH3-temperature programmed desorption (NH3-TPD). Result showed that the kinetics of hard coke combustion approximately fitted a first order reaction with respect to the amount of coke and, therefore, most of the coke existed in a monolayer state and the corresponding apparent activation energy was about 110 kJ·mol-1. There were three kinds of carbon species on the surface of the Cat-1000 catalyst, which presented the catalyst after 1000 h reaction. The C atom fractions in the presence of C—O, C=O, and —C—C— were 22.7%, 9.1%, 68.1%, respectively. The formed carbon species on the Cat-1000 catalyst surface was mostly a graphite structure. The results showed that three quarters of the total carbon deposition on Cat-1000 was hard coke and the rest was soft coke. The specific surface area of the Cat-1000 catalyst decreased obviously compared with the catalyst without reaction (Cat-0). The Cat-1000 had almost unchanged acid intensity as well as high activity and stability. This shows that the cokes mainly deposit on the binder.

 

Key words: Toluene disproportionation, Transalkylation, Carbon deposition, Catalyst, Thermogravimetry and differential thermal analysis

MSC2000: 

  • O643.36