级孔HZSM-5分子筛上超临界正十二烷催化裂解.pdf

石油化工
2015年第44卷第3期
PETROCHEMICAL TECHNOLOGY
级孔HZSM-5分子筛上超临界正十二烷催化裂解
刁振恒,王莅12,刘国柱2,张香文2
(1.天津大学化工学院,天津300072;2.先进燃料与化学推进剂教育部重点实验室,天津300072
摘要]以四丙基氢氧化铵( IPAOA)和四丁基氢氧化铵为碱源,在十六烷基三甲基溴化铵存在下,通过脱硅和再晶化合成了级
孔HZSM-5分子筛。采用XRD、TEM、N2吸附-脱附、原位Py-IR和NH3-TPD等方法表征了分子筛的结构和酸性,在500
℃、4MPa下考察了级孔HZSM-5分子筛涂层上超临界正十二烷催化裂解的性能。实验结果表明,用 TPAOH脱硅得到的级
FL HZSM-5分子筛具有较大的外比表面积、微孔体积及酸量,其活性较未处理的HZSM-5原粉提高了76%,失活速率下降了
61%。再晶化后,试样表面被MCM-41和HZSM-5碎片包裹,活性反而下降。表明 TPAOHI可缓和脱硅过程,保护分子筛的
微孔结构;开放的介孔结构和中等的强酸量,有利于改善级孔H2ZSM-5分子筛的催化裂解性能。
关键词]催化裂解;正十二烷;超临界;级孔HZSM-5分子筛;脱硅;再晶化;碳氢燃料
文章编号]10008144(2015)03-0287-06
中图分类号]TQ517,2
[文献标志码]A
Catalytic rackin of Super al -Dodecane over Hierarchical Hsm-5zeolites
Diao Zhenheng, Wang Li, Liu Guozhu2, Zhang Xiangwen 2
(1. School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China;
2. Key Laboratory for Advanced Fuel and Chemical Propellant of Ministry of Education, Tianjin 300072, China
I Abstract] Hierarchical HZSM- zeolites were prepared by desilication and recryst allization in the
presence of cetyl trimethyl ammonium bromide with tetrapropy lammonium hydroxide(TPAOH )or
tetrabutyl ammonium hydroxide as alkali source, and characterized by means of XRD, TEM, N2
adsorption otion n t P -R and NH - PD The a alytic cracking of supercritical n-dodecane over
the hierarchical HZSM-5 zeolite coatings was investi ated under the conditions of 500 and 4 Mpa. The
TPAOH desilicated zeolite exhibited larger external specific surface area, micropore volume and acidity
The average conversion of n-dodecane increased by 76% and the deactivation rate of the hierarchical
HZSM-5 zeolite decreased by 61% compared with he part HZM zli e After he recry allization
of TPAOH desilicated zeolite, its crystal surface was covered by MCM-41 and HZSM-5 fragments
which led to the decrease of the catalytic activity. This indicated that TPAOH as alkali source could protect
micropore structure of the zeolite ue o the slow desilication High opened mesopore structure and moderate
amount of strong acid were beneficial to the improvement of the catalytic cracking performances of the
catalysts
L Keywords] catalytic cracking; n-dodecane; supercritical; hierarchical HZSM-5 zeolite;
desilication recrystallization; hydrocarbon fuel
超临界条件下(3.4~6.9MPa,>400℃)进“热障”问题的一个有效途径,因而得到越来越广
行的碳氢燃料催化裂解过程,是解决高超声速飞行泛的关注12)。但超临界烃分子在分子筛微孔孔道
[收稿日期]2015-01-26;[修改稿日期]2015-01-28
[作者简介]刁振恒(1986一),男,山东省枣庄市人,博士生,电话02-27892340,电邮dacheng@tju.edu.cn。联系人:张香文,电话02
27892340,电邮zhangxiangwene@tju.edu.cn。
[基金项目]国家自然科学基金项目(21476168)。