摘要
以多壁碳纳米管(CNTs)为载体制备了负载型Pt催化剂Pt/CNTs并将其用于催化甲苯加氢脱芳(HDA)反应.结果表明,在1.0%Pt/CNTs催化剂上,在0.4MPa,373K,PhCH3/H2摩尔比=6/94和GHSV=120L/(h.g)的反应条件下,甲苯转化率可达100%,比反应速率为0.0523mmol/(s.m2),分别是γ-Al2O3和AC负载各自最佳Pt负载量催化剂1.4%Pt/γ-Al2O3和2.4%Pt/AC上相应值的1.17和1.18倍.甲苯加氢产物全部为甲基环己烷,其他可能的加氢产物均在气相色谱检测限以下.催化剂的表征研究揭示,用CNTs代替γ-Al2O3或AC作为载体并不会引起所负载Pt催化剂上甲苯HDA反应的表观活化能发生明显变化.与γ-Al2O3或AC负载的相应催化剂相比,一方面,CNTs负载的Pt催化剂易于在较低温度下还原活化,并且其工作态催化剂表面催化活性Pt物种(Pt0)所占表面Pt摩尔分率有所提高;另一方面,CNTs负载的Pt催化剂对H2具有较高的吸附/活化和储存能力.这些促进效应对催化剂HDA活性的提高都有重要贡献.
Using home-made multiwalled carbon nanotubes （CNTs） as the support, the Pt/CNTs catalyst was prepared by an incipient wetness method. Performance of the catalyst for hydrogenation-dearomatization （HDA） of toluene was evaluated and compared with the reference catalysts supported onγ-Al2O3 and activated carbon （AC）. Over the 1.0 % Pt/CNTs catalyst under the reaction conditions of 0.4 MPa, 373 K, PhCH3/H2 = 6/94 （mol/mol） and GHSV= 120 L/（h·g）, the observed conversion of toluene HDA reached 100%, and the corresponding specific reaction rate was 0.052 3 mmol/（s·m2）. This value was 1.17 and 1.18 times that of the 1.4 % Pt/γ-Al2O3 and 2.4 % Pt/AC catalysts with the respective optimal Pt loading, respectively. It was experimentally found that using CNTs in place of γ-Al2O3 or AC as the support of the catalyst did not cause a significant change in the apparent activation energy for the toluene HDA reaction but led to a slight increase in concentration of catalytically active Pt species （Pt^0） at the surface of the functioning catalyst. In addition, the Pt/ CNTs catalyst could reversibly adsorb a greater amount of hydrogen under atmospheric pressure at temperatures from room temperature to 573 K. This unique feature would help to generate a microenvironment with higher stationary state concentration of active hydrogen-adspecies at the surface of the functioning catalyst. These effects favored the toluene HDA reaction.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第3期210-216,共7页
基金
国家自然科学基金(20473063)
福建省科技重大项目(2005HZ01-3).
关键词
多壁碳纳米管
铂
负载型催化剂
甲苯
加氢脱芳
Key words, multiwalled carbon nanotube
platinum
supported catalyst
toluene
hydrogenation-dearomatization
作者简介
周敏，女，1980年生，硕士研究生．
