甲苯歧化与烷基转移催化剂的积碳行为  

Carbon Deposition on a Toluene Disproportionation and Transalkylation Catalyst

作　　者：蒙根[1] 孔德金[1] 祁晓岚[1] 许中强[1] 

机构地区：[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

出　　处：《物理化学学报》2010年第11期3017-3022,共6页Acta Physico-Chimica Sinica

基　　金：上海市科委科技攻关项目(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110kJ·mol-1;反应1000h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1000h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.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.

关 键 词：甲苯歧化 烷基转移 积碳 催化剂 热重-差热分析 

分 类 号：TQ203.2[化学工程—有机化工]