Study On The Synthesis Of Succinic Acid And Cyclic Carbonate From CO₂ And Olefins

Carbon dioxide is one of the green house gases.The emission and accumulation of a large amount of CO₂ causes a big negative effect on the global environment.From the view of chemistry,carbon dioxide is a safe and abundant C1 resource and can replace harmful reactants?such as CO and phosgene etc.?in chemical reaction process,to afford high value-added chemicals.So the conversion of utilization of CO₂ has a theoretical and application significant.This paper focused on the addition reaction of olefins with CO₂ to produce carboxylic acids and cyclic carbonates.It mainly consists of two parts,including the electrochemical synthesis of succinic from CO₂ and ethylene,and synthesis of cyclic carbonates via reaction of olefins with O₂ and CO₂ catalyzed by using mesoporous Co₃O₄/KI composite catalyst.?1?Succinic acid was synthesized from ethylene and carbon dioxide by an electrochemical route.With Ni as the cathode and Al as the sacrificial anode,ethylene could be successfully electrocarboxylated with CO₂?1.0 MPa?in an undivided cell containing n-Bu₄NBr-DMF electrolyte at a constant current under room temperature.After the electrolysis,succinic acid with a high selectivity and a high yield could be obtained by filtration,washing,acidification of filter residue,extraction and re-crystallization steps.The experimental results showed that the type of electrolytes,solvents,electrolytic time and electrode materials have great influence on the yield of succinic acid.?2?Cyclic carbonates were synthesized via the reaction of olefins with O₂ and CO₂catalyzed by using mesoporous Co₃O₄/KI composite catalyst.Firstly,Co₃O₄ catalysts were prepared by a microemulsion method with P123 as the template,a hydrothermal method and a solid-state method,respectively.The prepared Co₃O₄ catalysts were characterzed by powder X-ray diffraction,Nitrogen sorption studies,Scanning electron microscope,Transmission electron microscope,X-ray photoelectron spectroscopy and Thermogravimetric analysis.The Co₃O₄ catalyst obtained by a microemulsion method displays mesoporous sheet-like nano-structures with about 7 nm nano-pore,while the Co₃O₄ catalyst prepared by hydrothermal method or solid-state method exhibits rod and spherical nanoparticles with mesoporous structures respectively.For catalyzing the reaction of olefins with O₂ to form epoxide intermediates,the Co₃O₄ catalyst with mesoporous sheet-like nano-structures has better catalytic activity than the rod-Co₃O₄ and spherical-Co₃O_4.The effects of solvents,the way oxidant O₂ added and amount of O₂,pressure of CO₂ and types of co-catalyst on the reaction were systematically studied.The results showed that high yields of cyclic carbonates could be obtained by using DMF as the solvent and Co₃O₄/KI as the composite catalyst under100?via multiple process in one-pot.In addition,the catalytic activity of Co₃O₄ could be almost kept after reused several times.According to the relevant literature and the experimental results,the reaction mechanism was proposed.Namely,olefins undergo oxidation radical reaction to generate epoxy intermediates,followed by the cycloaddition reaction with CO₂ to form cyclic carbonates.