酸催化山梨醇脱水制异山梨醇的研究进展

Isosorbide is a biomass-derived functional diol, with wide applications in the synthesis of several pharmaceutical molecules and fine chemicals. It attracted much attention recently due to its potential applications in the polymer industry. The catalytic dehydration of sorbitol represents a key and challenging step in the synthesis of isosorbide from biomass. Up to now, the acid catalytic system has been extensively explored and significant progresses were made with respect to both of catalyst designing and process optimization. This review mainly provides the relationship between structure and activity of different acid catalyst types. The first section comprehensively introduces the acid-catalyzed dehydration of sorbitol to isosorbide and the mechanism involved. The following two sections describe the progresses made in the homogenous and heterogeneous catalysts, respectively. The homogeneous catalyst mainly includes Brφnsted mineral acids, Lewis acids and ionic liquids, and the focus of was put on the influence of acid sites, acidity, stability and reaction solvent to sorbitol dehydration. The heterogeneous catalyst mainly includes acid resin, zeolite, supported metal oxide, heteropolyacid, sulphate and phosphate metal oxides, acid polymer and macromolecule catalyst. In addition to acid sites, acidity and stability, the acid capacity, pore structure, and surface structure and nature also have importantly effects on the activity of heterogeneous catalyst. Moreover, the effects of preparation methods of heterogeneous catalysts on their properties will be discussed. This article pointed out that Brφnsted mineral acids of strong acidity provided better catalytic activity, which, however, had the worst corrodibility and are difficult to be recycled. Latest reported acidic ionic liquids with tunable acidity and non-volatility in principle enables catalyst recycling, which may become competitive catalysts to replace mineral acids. For the heterogeneous catalytic system, the catalytic activity is closely related to the composition and structure of catalysts launched. More researches about the relationship between structure and activity needs to be carried out to develop efficient solid catalyst.