Study On The Degradation Performance Of Ethylethanolamine Non-aqueous CO₂ Absorbent

CO₂ capture by alkanolamine method is one of the most effective ways,which is beneficial to alleviate the greenhouse effect.Organic alkanolamine method includes aqueous alkanolamine solution method and non-aqueous alkanolamine method.The non-aqueous alkanolamine solution is an ideal CO₂ absorbent with the advantages of high CO₂ absorption and low energy consumption compared to the aqueous alkanolamine solution.The non-aqueous solution of N-ethylethanolamine?EMEA?+Diethylaminoethanol?DEEA??denoted as EMEA non-aqueous solution?is a novel nonaqueous alkanolamine solution,which has high CO₂absorption loading?0.68 mol CO₂/mol EMEA?,high regeneration efficiency?91%?and low energy consumption?7554 kJ/kg solvent?.However,occur degradation mechanisms of EMEA include deethylation reaction,intramolecular cyclization reaction and intermolecular dehydration reaction,which lead to device corrosion,solution foaming,and solvent loss.The purpose of this thesis is to explore the degradation mechanism of EMEA non-aqueous solution and to find an effectiveanti-degradation method.For oxidative degradation,the ESI-MS was used to explore the oxidative degradation mechanism of EMEA non-aqueous solution.The experimental results show that the oxidation degradation mechanisms of EMEA are deethylation reaction,intramolecular cyclization reaction and intermolecular dehydration reaction,the main degradation products are glycolic acid,oxalic acid and other carboxylic acid compounds.The oxidation degradation mechanisms of DEEA are carboxylation reaction and intermolecular dehydration reaction,the main degradation products are polyamine compounds.The effect of oxidative degradation on the relative alkalinity,the EMEA mass content and the CO₂ absorption were explored,The experimental results show that the relative alkalinity is reduced by 9.88%the degradation rate of EMEA is 7.33%,and the reduction rate of CO₂ capacity is 6.74%after 30 days of oxidative degradation.The antioxidant effects of the six oxidation inhibitors?butanone oxime,acetaldoxime,acetone oxime,N,N'-Bis?salicylidene?-1,2-diaminopropane?BPPD?,pyrogallol and carbohydrazide?were studied.The experimental results show that the effects of the six oxidation inhibitors are in the order of:acetaldehyde oxime>butanone oxime>acetone oxime>BPPD?carboxhydrazide,pyrogallol has no effect,acetaldehyde oxime reduced the degradation rate of EMEA by 45.43%For thermal degradation,the ESI-MS was used to explore the thermal degradation mechanism of EMEA non-aqueous solution.The experimental results show that the thermal degradation mechanisms of EMEA are intramolecular cyclization reaction,intermolecular dehydration reaction and ethylation reaction,the main degradation products are oxazolidinone compounds and polyamine compounds.the thermal degradation mechanism of DEEA is intramolecular dehydration reaction,deethylation reaction,intermolecular dehydration reaction,intramolecular cyclization reaction and carboxylation reaction,the main degradation products are oxazolidinone compounds and polyamine compounds.The effect of thermal degradation on the relative alkalinity,the EMEA mass content and the CO₂ absorption were explored,The experimental results show that the relative alkalinity is rised by 7.30%,the degradation rate of EMEA is 43.53%,and the reduction rate of CO₂ capacity is 30.88%after 20 days'thermal degradation.The thermal degradation resistance of three non-aqueous compound solutions?PZ non-aqueous solution,ODZ non-aqueous solution and DEA non-aqueous solution?were studied.The experimental results show that the effects of the three compound solution are in the order of:PZ non-aqueous solution>ODZ non-aqueous solution.DEA non-aqueous solution has no thermal degradation resistance,and the PZ compound system has the best thermal degradation resistance,which reduces the degradation rate of EMEA by 21.50%.