Study On The Green Process Of Preparing Fumaric Acid By The Isomerization Of Maleic Acid

Fumaric acid is a kind of tetra-carbon unsaturated dicarboxylic acid,which is widely distributed in the natural environment and is often used in food,chemical,biological and other fields.In recent years,with the continuous expansion of the application of fumaric acid in materials,food preservation,and environmental fields,its market demand has continuously increased.Due to the problems of environmental pollution and low utilization rate of raw materials in traditional chemical synthesis and biotransformation fumaric acid production methods,it is urgent to develop a new green fumaric acid production method.Conventional fumaric acid preparation processes usually use substances such as strong acid and antimony pentoxide as catalysts,and thus generate a large amount of environmentally harmful waste water.In this paper,the green preparation of fumaric acid was achieved by a simple one-step hydrothermal synthesis method without using a catalyst.The product was identified by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy,and the obtained product was confirmed to be pure fumaric acid.Combined with scanning electron microscopy,the feasibility and stability of the method were verified.The optimal reaction conditions were determined by orthogonal experiment:the initial maleic acid concentration was 90%,the reaction time was 1 hour,and the reaction temperature was 200?.In addition,the specific variation of fumaric acid yield with various influencing factors was obtained by single factor experiment,which provided guidance for subsequent research.In order to further explain the influence of reaction temperature,reaction time and initial maleic acid concentration on the yield of fumaric acid,a kinetic model of the mutual conversion reaction of fumaric acid,maleic acid and malic acid was established.The reaction kinetic parameters of the reaction were calculated,and the simulation results were in agreement with the experimental data.Through the analysis of the kinetic parameters,the influence of various factors on the reaction is theoretically explained,and the reaction mechanism is revealed.In order to realize the green production of fumaric acid,the washing liquid is treated by washing liquid circulation and activated carbon adsorption separation,respectively.The research results show that the washing liquid circulation process can effectively increase the yield of fumaric acid without affecting the quality of the product,and the number of cycles can reach 6 times.In the activated carbon adsorption separation experiment,activated carbon can effectively adsorb the maleic acid and fumaric acid components in the washing liquid,so that the less selective malic acid can be separated and used as a by-product.Through the above research,the preliminary development of the related process of preparing fumaric acid with maleic acid as raw material and without catalyst was completed,which provided guidance for the development of green chemical process of fumaric acid and malic acid.