Honeycomb-structured solid acid catalysts fabricated via the swelling-induced self-assembly of acidic poly(ionic liquid)s for highly efficient hydrolysis reactions  

酸性聚离子液体溶胀诱导自组装形成类蜂窝状固体酸催化剂及其高效催化水解反应

作　　者：Bihua Chen Tong Ding Xi Deng Xin Wang Dawei Zhang Sanguan Ma Yongya Zhang Bing Ni Guohua Gao 陈必华;丁桐;邓熹;王鑫;张大卫;马三罐;张永亚;倪兵;高国华(华东师范大学化学与分子工程学院,上海市绿色化学与化工过程绿色化重点实验室,上海200062;剑桥大学化学系,英国剑桥CB21EW;华东师范大学生命科学学院,上海200241)

机构地区：[1]Shanghai Key Laboratory of Green Chemistry and Chemical Processes,School of Chemistry and Molecular Engineering,East China Normal University,Shanghai 200062,China [2]Department of Chemistry,University of Cambridge,Cambridge CB21EW,U.K. [3]School of Life Sciences,East China Normal University,Shanghai 200241,China

出　　处：《Chinese Journal of Catalysis》2021年第2期297-309,共13页催化学报（英文）

基　　金：国家自然科学基金(21773068,21573072,21811530273);国家重点研发计划(2017YFA0403102);上海市重点学科建设项目(B409).

摘　　要：The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging.In this study,acidic poly(ionic liquid)s with swelling ability(SAPILs)were designed and synthesized via the free radical copolymerization of ionic liquid monomers,sodium p-styrenesulfonate,and crosslinkers,followed by acidification.The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength.The thermogravimetric analysis results in the temperature range of 300–345°C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H)(245°C).Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional(3D)honeycomb structure in water,which was ascribed to the swelling-induced self-assembly of the molecules.Moreover,we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol,and determined that their catalytic activity was much higher than that of homogeneous acid catalysts.The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures.Depending on the reaction mixture,the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5–23.3 times higher than that outside of it,which suggested the high enrichment ability of SAPILs for cyclohexyl acetate.The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate,which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.酸催化反应在化学工业中占据着十分重要的地位.传统的液体酸催化剂催化性能优异,但面临着能耗高,腐蚀设备和环境污染严重等问题.相比于传统的液体酸催化剂,固体酸催化剂,如分子筛和磺酸树脂等大大缓解了经济和环境方面的问题,但也存在着催化活性差和易失活等缺陷.酸性聚离子液体因其高密度的反应活性位点,可设计调变的结构和酸性以及可循环利用等特性而成为一种新型的高效多相酸催化剂,引起了广泛的研究兴趣.然而,当酸性聚离子液体用作催化剂时,由于其酸中心不能充分地暴露在反应底物中,使得它们的催化活性难以达到甚至超越均相催化剂的水平.因此,发展一种催化活性高于均相的酸性聚离子液体催化剂仍是一个巨大的挑战.我们研究组发现在反应底物中溶胀的聚离子液体可作为一种准均相催化剂,其催化活性与相应的均相离子液体相当,这为提高多相催化剂的催化活性提供了一种新的策略.本文报道了一种在水中溶胀且自组装成类蜂窝状网络结构的酸性聚离子液体催化剂,该催化剂在水解和水合反应中表现出优异的催化性能,其活性高于均相酸催化剂.首先通过自由基聚合和酸化两步合成了一系列在水中高度溶胀的酸性聚离子液体(SAPIL-1-6).以三甲基磷氧(TMPO)为探针分子,用31P魔角旋转核磁共振(31P-TMPO NMR)对SAPILs的酸性进行了分析.结果表明,SAPILs具有中等强度的单一酸性.热重分析表明SAPILs拥有优异的热稳定性能(300-345℃),显著地优于商用磺酸树脂Amberlite IR-120(H)(245℃).扫描电镜和冷冻电镜表明,当SAPILs在水中溶胀时,无孔的结构会自发地形成微米级三维类蜂窝状网络结构.这些类蜂窝状网络结构的酸性聚离子液体在催化乙酸环己酯水解制备环己醇中表现出卓越的催化性能,其催化活性明显高于多相酸催化剂(Amberlite IR-120(H)和H-ZSM-5)和均�

关 键 词：Heterogeneous acid catalyst Acidic poly(ionic liquid) SWELLING 3D honeycomb structure Enrichment Hydrolysis HYDRATION 

分 类 号：TQ116.2[化学工程—无机化工] TQ426