The 8th International Congress on Ionic Liquids (COIL-8) was held in Beijing from May 13 to 17. This is the first time in China since the COIL was founded in 2005. This conference not only explored the latest academic frontiers in the field of ionic liquids, but also demonstrated the growing influence of ionic liquids in large-scale industrial applications. During the congress, JIANG Xiaochuan, an expert in the development and application of ionic liquids in China (also the deputy chief engineer of Yankuang Cathay Coal Chemicals Co., Ltd, and the Post-doctor of Chemistry of Beijing University of Chemical Technology), also released his achievements in the development of new ionic liquids, as well as the latest progress in research and industrial application of industrial catalysis and acid gas desulfurization using ionic liquids.
Ionic liquids, also known as low-temperature molten salts, are a class of organic liquids composed of ions entirely near room temperature. Its molecular structure determines its unique physicochemical properties, especially its non-volatility, conductivity and designability. as a new type of green solvent, Ionic liquids has attracted more and more attention in the field of reaction and separation technology. In recent years, due to the high attention to cleaner production, environmental protection and circular economy paid by the international community, as well as the scientific exploration value and great application potential of ionic liquids, ionic liquids have achieved rapid development. Many applications of ionic liquids are undergoing pilot or industry tests, and even have entered the stage of industrialization.
For the industrial application of ionic liquids, it is necessary to select environment-friendly ionic liquids with simple preparation process, high efficiency, low cost, low toxicity and biodegradability from many kinds of ionic liquids. JIANG Xiaochuan’s team has developed a new class of ionic liquids whose anion is alkyl phosphate. these ionic liquids are prepared in one step with mild reaction condition, simple operation, easy separation and high purity, its application prospects in some key chemical separation processes and environmental pollution control processes lay the foundation for the industrial application of ionic liquids.
The vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE) data of ionic liquid-containing systems are important components of basic chemical data. They are essential for evaluating the affinity between solvents and ionic liquids, developing thermodynamic models suitable for multicomponent systems containing ionic liquids, designing unit operations and optimizing chemical processes. For this reason, JIANG Xiaochuan’s team carried out the determination of the VLE data of ionic liquid-containing ethanol-methanol-water system and the LLE data of ionic liquid-gasoline-thiophene derivatives system, which laid the foundation for the application of ionic liquids in ethanol/water distillation separation and gasoline extraction desulfurization.
In recent years, JIANG Xiaochuan’team has also carried out research and industrial application of ionic liquids in industrial catalysis and acid gas desulfurization, and achieved good results. The results show that alkyl phosphate ionic liquids can promote carbonylation as well as esterification of acids and alcohols. In the reaction of methanol carbonylation, this ionic liquid can greatly improve the stability of rhodium complex, reduce the water content in the reaction system from 15% to less than 5%, and increase the reaction rate exponentially. Using ionic liquid catalytic system, JIANG Xiaochuan’s team increased the output of traditional industrial plants by more than twice with minimum investment, and achieved great economic benefits. In the esterification synthesis, ionic liquids were used instead of traditional sulfuric acid catalysts to develop reactive distillation for synthesis of methyl acetate and Ethyl acetate. These two processes have been successfully applied to the production of raw materials for carbonylation of methyl acetate to acetic anhydride and indirect hydrogenation of acetic acid to ethanol. these reactive distillation processes are characterized by less equipment, short process, nearly 99% conversion, 100% selectivity and low energy consumption.
Alkyl phosphate ionic liquids aqueous solution can efficiently absorb SO2 and H2S from the tail gas of Claus reactor by adding a small amount of activator, antioxidant and buffer and adopting the cycle-regeneration method. The sulfur emission from Claus tail gas is close to zero by regeneration reaction to form elemental sulfur, and the desulfurization method has been verified by industrialization and has good popularization value.
With the deepening of research, room temperature ionic liquids have shown good application prospects in many fields, such as reaction, separation, catalysis, desulfurization and so on. Ionic liquids are another kind of green solvents after water and supercritical carbon dioxide, which has become one of the hotspots in the research and application of green chemistry and chemical industry.