摘要
采用晶种导向的方法,以四丙基溴化铵为模板剂,乙胺为矿化剂,硅溶胶为硅源,氯化铝为铝源,60 nm Silicate-1为晶种,于水热条件下合成了具有不同b轴厚度及硅铝比的二维HZSM-5纳米片.采用不同碱源对分子筛进行碱处理,其中经NaOH处理以及NaOH与四丙基氢氧化铵(TPAOH)联合处理得到了二维多级孔HZSM-5纳米片.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、Ar吸附-脱附、氨-程序升温脱附(NH3-TPD)、X射线荧光光谱(XRF)和X射线光电子能谱(XPS)等手段对催化剂的结构和酸性进行了表征,考察了硅铝比和b轴厚度对催化苯与稀乙烯烷基化反应的影响.研究结果表明,在360℃,1. 4 MPa,苯烯比为6,乙烯体积分数为15%,乙烯质量空速(WHSV)为1. 5 h-1的反应条件下,随着硅铝原子比从80提高至200,苯的转化率略有下降,乙基选择性保持在99. 2%以上,但甲苯及二甲苯选择性分别从0. 11%和0. 09%均下降至0. 05%.将不同b轴厚度的HZSM-5纳米片催化剂在苯烯比为1的条件下进行实验发现,硅铝比为160的大晶粒HZSM-5催化剂失活严重,反应50 h时苯的转化率从34. 6%下降至8%,二甲苯选择性达到0. 37%;而b轴厚度为100 nm的二维HZSM-5纳米片作为催化剂时苯的转化率稳定在44. 0%,乙基选择性为94. 8%,二甲苯选择性下降至0. 22%,并在100 h内保持反应性能不变.
2D HZSM-5 nano-sheet with different b-axis thickness and Si/Al atom ratios were synthesized by seed-induced method under the hydrothermal conditions,using tetrapropylammonium bromide as the template,ethylamine as the mineralizer,silica sol as the silicon source,aluminium chloride as the aluminium source and the 60 nm silicate-1 as the crystal seed,respectively.And the 2 D hierarchical HZSM-5 nano-sheet were obtained by alkaline treatment with different sources,including NaOH treatment,tetrapropylammonium hydroxide(TPAOH)treatment,and NaOH with TPAOH co-alkaline treatment.The structure and acidity of the samples were characterized by means of X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Ar adsorption-desorption,ammonia temperature-programmed desorption(NH3-TPD),X-ray fluorescence(XRF)and X-ray photoelectron spectroscopy(XPS).The effects of Si/Al atom ratio and the thickness of b-axis on the alkylation of benzene with dilute ethylene were investigated.The research results show that,under the reaction conditions of 360℃,1.4 MPa,the molar ratio of benzene/ethylene is 6,and the concentration and weight hourly space velocity(WHSV)of ethylene were 15%and 1.5 h-1,the conversion of benzene decreased slightly with the increasing of Si/Al atom ratio,the ethyl selectivity maintained above 99.2%,while the selectivity of toluene and xylene decreased from 0.11%and 0.09%to 0.05%,respectively.The HZSM-5 catalysts with different b-axis thickness were evaluated under the condition of benzene/ethylene is 1,the microscale HZSM-5 with the high silica content deactivated seriously.The conversion of benzene declined from 34.6%to 8%during 50 h,and the ethyl selectivity was 88%.While the benzene conversion of 2D HZSM-5 nano-sheet with same Si/Al atom ratio was stable at 44.0%,the ethyl selectivity reached to 94.8%,and the xylene selectivity reduced from 0.37%to 0.22%.
作者
边凯
候章贵
段欣瑞
李孝国
常洋
曹辉
张安峰
郭新闻
BIAN Kai;HOU Zhanggui;DUAN Xinrui;LI Xiaoguo;CHANG Yang;CAO Hui;ZHANG Anfeng;GUO Xinwen(State Key Laboratory of Fine Chemicals,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,China;CNOOC Research Institute of Refining and Petrochemicals,Beijing 102209,China)
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第4期784-792,共9页
Chemical Journal of Chinese Universities
关键词
HZSM-5分子筛
酸催化
乙苯
苯与乙烯烷基化
HZSM-5 zeolite
Acid catalysis
Ethylbenzene
Alkylation of benzene with ethylene
作者简介
联系人:张安峰,男,博士,副教授,主要从事分子筛酸催化方面的研究.E-mail:zhangaf@dlut.edu.cn;联系人:郭新闻,男,博士,教授,博士生导师,主要从事分子筛酸催化及二氧化碳加氢还原方面的研究.E-mail:Guoxw@dlut.edu.cn。
