摘要
苯与合成气的烷基化反应旨在利用非石油资源生产甲苯、二甲苯等烷基苯,本工作采用甲醇蒸气预积炭制备一系列的ZSM-5分子筛,并与ZnCrOx复合形成双功能催化剂,探索对苯和合成气烷基化制烷基苯的影响。通过对预积炭时间的考察,发现适当的预积炭能显著提高ZSM-5分子筛的催化性能。在450℃、4.0 MPa的反应条件下,预积炭改性24 h的催化剂苯转化率达到20.18%。对预积炭改性的ZSM-5分子筛和反应后的复合催化剂进行分析,表明预积炭改变了分子筛的酸性。预积炭覆盖了ZSM-5分子筛上的一些B酸位点,降低了B/L酸比,从而提高苯的转化率。最后,通过烃池机理对苯与合成气烷基化反应的失活机理进行合理推测。
Toluene,xylene and other alkylbenzenes are important basic chemical raw materials,which mainly come from the petrochemical industry.With the increasing foreign dependence of petroleum resources in China,the development of coal-to-aromatics technology can not only alleviate the problem of shortage of petroleum resources in China,but also promote the transformation and upgrading of consumption in the traditional coal chemical industry and promote the clean and efficient use of coal.In this paper,methanol-modified ZSM-5 molecular sieves were used and mechanically milled with ZnCrOx in a mass ratio of 3∶1 as a composite catalyst,so as to investigate the catalytic effect of pre-preg carbon modified ZSM-5 molecular sieves.Under the reaction conditions of 450℃and 4.0 MPa,the catalytic performance of the catalyst modified with pre-built carbon for 24 h was the best,in which the conversion of benzene reached 20.18%and that of CO reached 46.55%.It was found that the catalytic performance of the pre-built carbon modified ZSM-5 sieve was mainly affected by the B acid/L acid ratio,and the pre-built carbon covered some B acid sites on the ZSM-5 sieve,which reduced the B acid/L acid ratio and led to an increase in the benzene conversion,while the crystalline and pore structures of the pre-built carbon modified ZSM-5 sieve did not undergo significant changes.changed significantly.In order to better understand the deactivation mechanism of the carbon-modified ZSM-5 catalyst,TG-MS,Raman and GC-MS were used to further analyze the carbon species,and it was found that the carbon species of the carbon-modified ZSM-5 molecular sieves were mainly low-temperature carbon,which was mainly due to the fact that the strong acid was partially covered by the carbon-modified composite catalyst with the reduced amount of acid,and the carbon species were alkanes,olefins,aromatics and other oligomers mainly.Soluble carbon,high-temperature carbon and graphitic carbon are less,so as to avoid the reduction of catalyst activity caused by excessive
作者
刘秀全
赵志仝
唐明兴
徐红
代璞
葛晖
李学宽
LIU Xiuquan;ZHAO Zhitong;TANG Mingxing;XU Hong;DAI Pu;GE Hui;LI Xuekuan(Shanxi Key Laboratory of Chemical Product Engineering,College of Chemical Engineering and Technology,Taiyuan University of Technology,Taiyuan 030024,China;Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China)
出处
《燃料化学学报（中英文）》
EI
CAS
CSCD
北大核心
2024年第10期1516-1528,共13页
Journal of Fuel Chemistry and Technology
基金
国家自然科学基金(22078351,22072173,U1910202)
山西省自然科学基金青年科学研究项目(20210302124465)
国家重点研发计划(2023YFB4103300)
山西省重点研发计划(202102090301005)
师市重大科技揭榜挂帅项目(2022JB02)资助。
关键词
ZSM-5
预积炭
B/L酸比
苯烷基化
ZSM-5
pre-accumulation of carbon
B/L acid ratio
phenylalkylation
