Investigation On The Absorption Of CO₂ Catalyzed By Carbonic Anhydrase In Rotating Packed Bed

After the Industrial Revolution,greenhouse gas emissions have soared,leading to an increase in global average temperature,which has brought great challenges to normal production and life of human beings.Therefore,it is very important to control the emission of greenhouse gas CO₂.The chemical absorption method using organic alcohol amine solvent as absorbent is the most widely used and mature technology in CO₂capture process.However,the high cost of absorbing liquid regeneration and high equipment investment limit the popularization and application of this technology.Therefore,the development of absorbent formulation systems with low regeneration energy consumption and the use of high-efficiency absorption equipment are the keys to improving the feasibility of chemical absorption methods for industrial CO₂capture.This work intends to use tertiary amines with good chemical stability and low energy consumption such as methyldiethanolamine（MDEA）as absorbents to reduce the energy consumption of CO₂capture process.By adding carbonic anhydrase catalyst（Carbonic Anhydrase,CA）with good catalytic effect,the reaction rate of MDEA and CO₂was significantly improved.A high-gravity reactor with significant advantages in mass transfer,Rotating Packed Bed（RPB）,is used as an absorption device to reduce equipment investment.In this work,the reaction kinetics of CA catalyzed tertiary amine solution with CO₂was studied by stopped-flow spectrometer,and the catalytic mechanism and catalytic effect of CA were analyzed.Then,using RPB as the absorption equipment,the actual strengthening effect of CA on the absorption of CO₂by tertiary amine solution was studied,which provided data support for the technical development of RPB and CA to synergistically enhance the absorption of CO₂by tertiary amine solution.Finally,a simple low pressure desorption process was designed and built,and the low pressure desorption process of CO₂absorbent was studied.The main contents of the study are as follows:1.The reaction rates of tertiary amine solutions with and without CA added and CO₂were measured by stopped-flow spectrometer,and the catalytic mechanism of CA was described by Michaelis-Menten equation.The results show that the addition of CA can greatly accelerate the reaction rate of the tertiary amine solution with CO₂.The enzyme concentration was positively correlated with the enzymatic reaction rate.Empirical power-law equations are applied to describe the kinetics of the reaction between aqueous tertiary amines and CO₂.The Michaelis-Menten equation model can accurately predict the reaction rate of CA-catalyzed tertiary amine solution with CO₂.2.The effects of different tertiary amine absorbents and operating conditions on CO₂removal were investigated in an RPB with an outer diameter of 10 cm,and the RPB with an outer diameter of 30 cm was used as the absorption device to carry out a scale-up experiment.The study showed that the CO₂removal rate increased with the increase of CA concentration,RPB rotational speed and liquid flow rate,and finally leveled off,while the increase of gas flow rate and CO₂loading in the absorbent would lead to the decrease of CO₂removal rate.Tertiary amine absorbents with higher p Ka values have higher CO₂removal with or without the addition of CA.The results of absorption experiments in RPB with an outer diameter of 30 cm verified the effect of several operating conditions on the CO₂removal rate,and the data showed that the CO₂removal rate of tertiary amine solution was improved to 94%under the catalysis of CA.3.The influence of operating conditions on the desorption rate in the low-pressure desorption unit was explored.The results showed that the increase of MDEA concentration would prolong the desorption time.The degree of vacuum,desorption temperature and stirring speed all had positive effects on the desorption rate.