Green Electrochemical Synthesis Of Succinic Acid

This dissertation aims at the development of a green electrochemical synthetic process of succinic acid. The basic principle of the electrosynthesis of succinic acid was investigated firstly. Then, operation factors of the process at pilot scale were studied in detail and optimized by orthogonal experiments. Finally, the process of industrial-scale production of succinic acid by electrochemical method was designed based on the experimental results obtained.First of all, the basic principle of the electrosynthesis of succinic acid was validated and the applicability of multi-component Pb-based alloy as the cathode in this process was investigated. The results show that the Pb-Sb-Cd-Sn alloy with 1.7% Sb, 3.15% Cd and 0.34% Sn is the best cathode material for the electrosynthesis of succinic acid.Then, cathode current density, electrolyte temperature, concentration of maleic acid and flow rate of electrolyte were selected as the main factors of the electrosynthesis of succinic acid and studied in detail. The experiments show that current efficiency decreases gradually with the increasing of cathode current density, and increases with the increasing of electrolyte temperature, concentration of maleic acid and flow rate of electrolyte, respectively.In succession, the electrosynthetic process was optimized by orthogonal experiments based on the following 5 main factors: cathode current density, electrolyte temperature, concentration of H₂SO₄, concentration of maleic acid and flow rate of electrolyte. The results show that cathode current density is the major factor for the electrosynthesis of succinic acid, and the significance of the other four factors is in the following turn: concentration of H₂SO₄, concentration of maleic acid, electrolyte temperature and flow rate of electrolyte. Based on the results of orthogonal experiments and taking the practical industrial production into account, the most suitable operating condition is determined, i.e., current density of 10.0 A/dm², 0.50 mol/L H₂SO₄, 160 g/L maleic acid, electrolyte temperature of 50℃and electrolyte flow rate of 0.15 m/s.Based on the above experimental results, the process of industrial-scale production of succinic acid by electrochemical method was designed. Specially, a computerized scheme is projected to control the process of electrosynthesis of succinic acid. During the design of the industrial production process, an optimizing route of electrosynthesis is selected, and a electrolytic reactor with the production capability of 1000 t/a succinic acid is schemed out. The material balance and cost-effectiveness analysis are carried out based on the 1000 t/a process of electrosynthesis of succinic acid.For computerized controlling of the electrolytic process, a chief monitoring system with a factory-station-layer framework and an interval monitoring subsystem are devised. The computerization of the controlling of the electrolytic process is achieved by the organic combination of these two systems. To meet the special demands of the electrolytic process, a CSC2000 system with tailor-made equipments is introduced to fulfill the computerized controlling.The experimental results show that, compared with batch production, the continuous electrolytic process designed in our work is more suitable for the production of succinic acid. The average current density and current efficiency increase 15% （i.e. space-time yield of the devices increases 15%） and 2～3%, respectively, which result in the great decrease of energy consumption. In addition, computerization of the electrolytic process benefits for eliminating higher harmonic wave and improving power factor during the industrial production.