Preparation Of Alkaline Catalyst And Its Catalytic Performance In Hydrolysis And Transesterification Reactions

With the development of environment protection and sustainable chemistry,green chemistry has been attracted more and more attention.In order to overcome drawbacks of traditional alkaline catalysts such as equipment corrosion,environmental pollution and difficulty of catalyst recycle,study on new type of alkaline catalyst is growing rapidly with significant progress.In this thesis,two kinds of alkaline catalysts functionalized ionic liquids and bimetal oxides CeO₂/MgO were synthesized and their catalytic activities were also explored in hydrolysis and transesterification reactions.The details are as follows:1.Four tetramethylammonium-based amino acid ionic liquids were designed and synthesized.The hydrolysis of cinnamaldehyde to natural benzaldehyde was investigated systematically using these four amino acid ionic liquids.The results indicated that tetramethylammonium prolinate?[N1111][Pro]?can be a powerful catalyst for the highly efficient hydrolysis of cinnamaldehyde,in which natural benzaldehyde was obtained with almost 94% yield and over 99% selectivity in 1 h.Moreover,kinetic study showed that compared with other catalysts,the catalytic system of [N1111][Pro] has a lower activation energy of 38.30 kJ·mol-1in the hydrolysis reaction,indicating superior catalytic performance of [N1111][Pro].Quantum-mechanical calculations further manifested that such high performance originates from the cooperative catalysis of the secondary amino and carboxyl group in the anion [Pro].2.Three carboxylate ionic liquids were designed,prepared and used for the synthesis of diethyl carbonate?DEC?via the transesterification reaction of dimethyl carbonate?DMC?with ethyl alcohol?EtOH?.The results indicated that the more carboxylate groups the ionic liquids have,the higher catalytic activities the ionic liquids show.The sequence is as follows: [N2222]3[NTA] > [N2222]2[IDA] >[N2222][Pipe].The optimized reaction conditions was time of 2 h,temperature of95 °C,catalyst amount of 1 wt.%,Et OH:DMC molar ratio of 4:1,in which the yieldwas 61%.3.A series of bimetal oxides CeO₂/MgO with different mole ratio?x = 2.5,6.5,8.5?were synthesized and used as catalysts for the synthesis of 5-hydroxymethyl furfurol ester?5-HMF ester?.The results indicated that?2.5?CeO₂/MgO showed the best catalytic performance with 94% yield of 5-HMF ester.It is validated from the characterization results of XRD and CO₂-TPD that?2.5?CeO₂/MgO has the smallest crystallite size and possesses the largest amount of base site from surface lattice oxygen,resulting in the excellent yield of 5-HMF ester.In addition,the transesterification reaction of other alcohols such as cyclic alcohol and long chain alcohol using?2.5?CeO₂/MgO as catalyst were further studied and all the yields of product esters were more than 80%.