复合离子液体C_4烷基化催化性能的红外光谱判据研究

采用傅里叶变换红外光谱(FTIR)对(C_2H_5)_3NH]Cl/xAlCl_3-yCuCl 复合离子液体进行了表征,着重比较了 CuCl 含量不同的复合离子液体的 FFIR 谱图;在288 K、搅拌转速1 500 r/min、异丁烷与2-丁烯摩尔比为10:1的条件下,考察了复合离子液体催化剂对异丁烷/2-丁烯烷基化反应的催化性能。实验结果表明,当复合离子液体的 FTIR 谱图在1636～1685 cm~(-1)区域内仅在1 636 cm~(-1)处出现吸收峰时,烷基化产物中三甲基戊烷(TMP)的质量分数小于40%,而当1636～1685 cm~(-1)区域内出现分裂峰(1 636,1 685 cm~(-1)处)时,产物中 TMP 的质量分数大于80%。根据复合离子液体的 FTIR 谱图在1636～1685 cm~(-1)区域内的变化,可以判断复合离子液体中是否存在大量 Al-Cu 配位离子,并可作为评价复合离子液体催化剂烷基化性能的判据。

FTIR Criterion in Determination of Catalytic Performance of Composite Ionic Liquids for Isobutane/Butene Alkylation

The composite ionic liquids of(C_2H_5)_3NH]Cl/xAlCl_3-yCuCl were characterized by FTIR.The effect of CuCl content on FTIR spectrum of the composite ionic liquids was particularly investigated.Under operational conditions:288 K,stirring speed 1 500 r/min,n(isobutane):n(2- butene)10:1,alkylation of isobutane with 2-butene by using the composite ionic liquid as catalyst were studied.For producing alkylate(mass fraction of trimethylpentanes less than 40%),only one 1 636 cm~(-1)absorption peak of composite ionic liquids emerged at FTIR absorption band of 1 636- 1 685 cm~(-1).But in case of producing alkylate(mass fraction of trimethylpentanes more than 80%), the absorption band of 1 636-1 685 cm~(-1)was splitted into 1 636,1 685 cm~(-1)absorption peaks. Therefore the variation of FTIR absorption band of composite ionic liquids in range of 1 636- 1 685 cm~(-1)can be taken as criterion to determine quickly and reliably the quality of composite ionic liquids and its performance in alkylation.