摘要
为了调控HZSM-5分子筛酸性,提升二甲苯异构化反应性能,对HZSM-5分子筛进行碱金属或碱土金属离子(M)交换制备不同nM/nAl(M=Li、Na、K、Rb、Cs、Mg、Ca、Sr、Ba)的HZSM-5分子筛样品,采用XRD、XRF、27Al MAS NMR、氮气物理吸附-脱附、吡啶吸附红外等手段对分子筛样品进行表征,并考察其催化二甲苯异构化反应性能。结果表明:碱金属及碱土金属离子交换不会明显影响HZSM-5分子筛孔道结构;随着制备过程初始配比n_(M)/n_(Al)从0.1逐渐增加至1.3,金属离子交换HZSM-5分子筛样品的n_(M)/n_(Al)逐渐升高,导致其Bronsted(B)酸酸量/Lewis(L)酸酸量比值(简称B/L酸量比)呈现降低趋势;同族金属中,金属离子交换HZSM-5分子筛样品的B/L酸量比降幅随原子序数的升高而增大,碱金属离子交换样品的B/L酸量比降幅较碱土金属离子交换样品更为显著。尽管HZSM-5分子筛样品中较低的B/L酸量比会降低乙苯转化率,但是有利于降低分子间歧化与烷基转移反应与分子内甲基顺位迁移反应比值,提高反应产物中对二甲苯/邻二甲苯摩尔比,可以获得更高的二甲苯收率和对二甲苯在二甲苯异构体中的占比。
To regulate the acidity of HZSM-5 zeolite and enhance its performance in xylene isomerization,a series of HZSM-5 zeolite samples with varying nM/nAl ratios(M=Li,Na,K,Rb,Cs,Mg,Ca,Sr,Ba)were prepared by alkali metal or alkaline earth metal ion(M)exchange.The zeolite samples were characterized using XRD,XRF,27Al MAS NMR,nitrogen physisorption-desorption,and pyridine adsorption infrared spectroscopy(Py-IR),and their catalytic performance in xylene isomerization was investigated.The results show that alkali metal and alkaline earth metal ion exchange has no significant effects on the pore structure of HZSM-5 zeolite.As the initial n_(M)/n_(Al) ratio in the preparation process increases from 0.1 to 1.3,the corresponding n_(M)/n_(Al) values of the metal ionexchanged HZSM-5 samples also increases.This has led to a decreasing trend in the ratio of B acid amount to L acid amount(referred to as the B/L acid amount ratio).For the homologous metals,the B/L acid amount ratio of metal ion-exchanged HZSM-5 samples decreases more significantly with increasing atomic number.Moreover,the decrease in the B/L acid amount ratio of alkali metal ionexchanged samples is more significant than that of alkaline earth metal ion-exchanged samples.Although a lower B/L acid amount ratio in metal ion-exchanged HZSM-5 samples can reduce the conversion rate of ethylbenzene,it helps to decrease the ratio of intermolecular disproportionation and alkyl transfer reactions to intramolecular methyl group migration reactions,and then increase the molar ratio of pxylene to o-xylene in the reaction products,thus achieving the enhanced xylene yield and a high proportion of p-xylene among xylene isomers.
作者
王宇
高宁宁
钟进
拓鹏飞
高俊魁
陈甜甜
王辉国
WANG Yu;GAO Ningning;ZHONG Jin;TUO Pengfei;GAO Junkui;CHEN Tiantian;WANG Huiguo(SINOPEC Research Institute of Petroleum Processing Co.,Ltd.,Beijing 100083,China)
出处
《石油学报(石油加工)》
北大核心
2026年第1期33-42,共10页
Acta Petrolei Sinica(Petroleum Processing Section)
基金
中国石油化工股份有限公司科研开发项目(224177)基金资助。
