引入Al_(2)O_(3)对Pt/ZSM-23催化剂加氢异构性能的调控  

Manipulation of hydroisomerization performance on Pt/ZSM-23 by introducing Al_(2)O_(3)

作　　者：白迪 孟记朋 邹驰 李闯[1] 梁长海[1] BAI Di;MENG Ji-peng;ZOU Chi;LI Chuang;LIANG Chang-hai(Laboratory of Advanced Materials and Catalytic Engineering,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学化工学院先进材料与催化工程实验室,辽宁大连116024

出　　处：《燃料化学学报（中英文）》2023年第2期175-185,共11页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(22038008);辽宁省“兴辽英才计划”(XLYC1908033);大连市支持高层次人才创新创业项目计划(重点领域创新团队支持计划项目2019RT10);中央高校基本科研业务费(DUT21TD103)资助。

摘　　要：采用双模板剂合成了ZSM-23分子筛,并制备ZSM-23-Al_(2)O_(3)复合载体,通过引入Al_(2)O_(3)调控Pt/ZSM-23催化剂的正十六烷(n-C_(16))加氢异构性能。采用XRD、SEM、TEM、N_(2)物理吸附-脱附及NH_(3)-TPD等方法探讨Al_(2)O_(3)对催化剂结构性质和化学性质的影响。结果表明,引入Al_(2)O_(3)可以提高Pt在复合载体上的分散度,降低催化剂的酸性位点浓度,有效调控了催化剂的金属-酸性浓度平衡(C_(Pt)/C_(A))。适宜的金属-酸性浓度平衡有利于提高对异构产物的选择性并抑制裂化副反应。Al_(2)O_(3)同时对ZSM-23晶粒起到了分散作用,改善了其分子筛纳米晶粒团聚现象,增加了ZSM-23中孔口的暴露数量,促进反应物和中间体的扩散。复合载体催化剂呈现了出色的异构选择性,其中,Pt/(9Z-1Al)催化剂由于具有适宜的金属-酸性浓度平衡呈现最高的异构产物收率,可达60%,明显高于Pt/ZSM-23催化剂的异构体收率(42%)。反应温度低于310℃时,Pt/ZSM-23催化剂的吸附模型符合孔口吸附,而高温时则为锁钥吸附。引入Al_(2)O_(3)后ZSM-23有更多相邻孔口暴露,吸附模型以锁钥择形为主,导致了7/8Me-C_(15)异构产物的大量生成。ZSM-23 zeolite was successfully synthesized in a dual-template system,and ZSM-23-Al_(2)O_(3)composites with different ratios were also prepared.The hydroisomerization performance of Pt/ZSM-23 catalyst was manipulated by introducing Al_(2)O_(3),and the influence of Al_(2)O_(3)on physicochemical properties was investigated by XRD,SEM,TEM,N_(2) physical adsorption-desorption and NH_(3)-TPD characterizations.The results showed that Al_(2)O_(3)improved the dispersion of Pt,significantly reduced the acid sites concentration of the catalyst,and regulated the metal-acid balance in quantitative.The suitable metal-acid balance concentration could improve the selectivity of isomers and suppress the cracking reactions.Meanwhile,Al_(2)O_(3)dispersed the ZSM-23 grains,which improved the dispersion and increased the number of exposed pores in ZSM-23.Thus the diffusion efficiency of reactants and intermediates could be promoted and the isomer products selectivity could be improved.All composite catalysts showed high selectivity of isomer products,among which,Pt/(9Z-1Al)had the highest yield of isomer products due to its suitable metal-acid concentration balance,reached 60%at 340℃,which was a significant improvement compared with Pt/ZSM-23(42%).When the reaction temperature was lower than 310℃,the pore mouth mechanism dominated in Pt/ZSM-23,while the key-lock mechanism was significantly strengthened at higher reaction temperature.After the introduction of Al_(2)O_(3),more adjacent pores in ZSM-23 were exposed and the key-lock mechanism became the domination,which led to a large number of 7/8Me-C_(15) isomers.

关 键 词：ZSM-23 Al_(2)O_(3) 加氢异构 正十六烷 

分 类 号：O643.32[理学—物理化学]