[BMIM]Cl-AlCl_3离子液体酸性调变对催化正戊烷异构化性能的影响

Influence of acidity adjustment on catalytic performance of [BMIM]Cl-AlCl_3 in isomerization of n-pentane

氯铝酸离子液体具有优良的催化轻质烷烃异构化性能,为研究该类离子液体酸性调变对其催化异构化性能的影响,分别向1-丁基-3-甲基咪唑氯铝酸离子液体([BMIM]Cl-AlCl_3)中添加ZnCl_2(L酸)和氯化(1-甲基-3-羧甲基咪唑)([cmmim]Cl,B酸),并通过紫外-可见吸收光谱和乙腈吸附红外光谱对改性离子液体酸性进行测定,考察了其对离子液体催化正戊烷异构化反应活性的影响。结果表明,改性离子液体的酸性随ZnCl_2质量分数的增加而逐渐减弱,催化正戊烷异构化反应活性也随之减弱,但异构烷烃的选择性增强;而添加少量[cmmim]Cl后的改性离子液体酸性先增加后降低,但随着[cmmim]Cl质量分数的增加,离子液体黏度不断上升,催化正戊烷异构化的活性呈现逐渐降低趋势。

Chlorine aluminate ionic liquid has an excellent catalytic performance on isomerization of light paraffin.In order to investigate the effect of acidity adjustment on the catalytic isomerization performance of chlorine aluminate ionic liquid,ZnCl2( L acid) and [cmmim]Cl( B acid) are added into [BMIM]Cl-AlCl3 ionic liquid,respectively.The acidity of the modified [BMIM]Cl-AlCl3 ionic liquids is characterized by UV-Vis spectra and acetonitrile adsorption FT-IR spectra,while the catalytic performance of the modified [BMIM]Cl-AlCl3 ionic liquid on n-pentane isomerization is also studied.The results show that with the increasing amount of ZnCl2,both the acidity and the catalytic activity of the modified ionic liquid decrease while the selectivity of iso-paraffins is improved. The acidity of the ionic liquid adding a few amounts of [cmmim]Cl becomes stronger firstly and then drops.But these two indexes both drop when the amount of[cmmim]Cl increases continuously.