Development And Thermal Degradation Properties Of New High-performance CO₂ Absorbent

The CO₂emitted from the combustion of fossil fuels such as coal,oil,and natural gas is the main cause of the greenhouse effect,among which coal-fired power plants are the largest source of CO₂emissions.At present,the chemical absorption method based on organic amine aqueous solution is the most mature and commercialized technology for CO₂capture in industry.The chemical absorption method has the advantages of high capture efficiency,low cost and simple process,but the traditional absorbent MEA used in this method has problems such as foaming,easy degradation,easy corrosion equipment,difficult regeneration and high energy consumption during operation.Therefore,the development of new absorbents with high efficiency,low energy consumption and stability to replace MEA has become the focus of current research.The main work of this paper is as follows:（1）Diethylene triamine（DETA）and organic amine NI were selected as the main absorbent,with tertiary amine CE,N-hydroxyethyl piperazine（ACP）and 2-amino-2-methyl-1-propanol（AMP）were selected as the auxiliary absorbent.Mixed them according to different mass ratios,and systematically studied the absorption and desorption properties of the mixed absorbent.The30 wt%DETA+10 wt%CE and 40 wt%NI+10 wt%CE showed better absorption and desorption properties.Then we performed multiple absorption and desorption cycle experiments on 40 wt%NI+10 wt%CE and 30 wt%DETA+10 wt%CE,and found that the NI+CE compound absorbent had better cycling stability.The absorption capacity of NICE absorbent was 3.71 mol/L,the desorption capacity was 3.55 mol/L and desorption rate was 95.62%,which was 1.35 times,1.46 times and 1.09 times of 30 wt%MEA respectively.（2）In order to further verify the industrial application potential of NICE absorbent,the reaction heat,corrosiveness and energy consumption of NICE and MEA were investigated.The results showed that the reaction heat of the absorbent NICE was between 55 and 82 k J/mol,which was 25.45-38.89%lower than that of MEA.Its average corrosion rate was 0.016 mm/a,which was 80%lower than that of MEA.The regeneration energy consumption and liquid-gas ratio of its pilot test process were 2.85 GJ/t CO₂and 1.83 L/m³,respectively.Compared with the MEA pilot test results,its energy consumption was reduced by 28.75%,and the liquid-gas ratio was reduced by49.7%.（3）In order to solve the problem of easy degradation of organic amine absorbent in industrial application,the thermal degradation experiment was conducted by using autoclave.Firstly,the effects of various organic amine absorbents on the degradation of organic amines at different temperatures,CO₂loadings and mass fractions were investigated.The study found that the degradation rate was positively correlated with temperature,CO₂loadings and mass fractions.In addition,the organic amine NI at 130℃and the degradation at 150℃is more obvious.Then,the thermal degradation performance of NI was improved by adding 1.5 wt%of different anti-degradants（A～F）,in which the best antidegradant was F.It decreased the degradation rate of Ni by15.19%at 130℃and 12.9%at 150℃.