Carrier Selection And Experimental Study On Regeneration Reaction Of Potassium Based Sorbent For CO₂Capture

CO2removal technology using solid alkali-based sorbents is a new emerging carbon dioxide capture and separation technology in recent years, it is curing sorbents on the basis of absorption separation, the main reaction agent of alkali metal carbonate loads on the surface of the porous material, through the gas-solid reaction to achieve the purpose of CO2capture. The technology with the advantage of low energy consumption, no corrosion to equipment, high recycled utilization efficiency, no secondary pollution and the low reaction temperature requirements has become a current research hot spot.The potassium based sorbent is not easy to produce sintering phenomenon in the process of reaction, and it is advantageous to the reaction. In addition, the microstructure and morphology of the hexagonal system K2CO3is better than the monoclinic system K2CO3, so this article selects KHCO3as the active components of the potassium based supported sorbent Through the chemical composition analysis of coal fired fly ash, Suzhou river sediment and zeolite, at the same time, in view of the zeolite has the advantage of large specific surface area, developed stable channel and stable nature, and its rich reserves in our country, this article chooses zeolite as the carrier material of preparation of carbon dioxide dry absorbent. Through comparison and analysis, this paper chooses13X zeolite with the larger specific surface area as the carrier material, the analogue regenerant of potassium based zeolite molecular sieves supported dry sorbent is mainly composed of active component, carrier materials and binder, pure KHCO3is determined to be the active component,13X zeolite is choosed as the carrier materials, Na2SiO4is used to be the binder, the sorbent preparation steps mainly include grinding, mixing, drying and calcination.First of all, scanning electron microscope (ESEM) has been used to characterize the potassium based coal fired fly ash supported sorbent and potassium based13X zeolite molecular sieves supported sorbent, and analysis their surface morphology and microstructure. Secondly, KHCO3decomposition experiment was carried out, the characteristics of KHCO3decomposition was studied in different heating rate and at different final temperature under nitrogen atmosphere. Then, potassium based zeolite molecular sieves supported sorbent and potassium based coal fired fly ash supported sorbent regeneration reaction experiment were carried out in different heating rate and at different final temperature. Based on the comparison of isothermal and non-isothermal dynamic analysis method, the non-isothermal analysis dynamic method was selected to solve the regeneration reaction kinetics parameters of potassium based sorbent for CO2capture.The results show that the starting temperature of potassium based zeolite molecular sieves supported sorbent regeneration reaction is114.3-119.0℃, and the ending temperature is246.2～250.3℃; the maximum reaction rate is0.68mg/min in the heating rate of15℃/min. The starting temperature of potassium based coal fired fly ash supported sorbent regeneration reaction is100-150℃, and the ending temperature is225-275℃; the maximum reaction rate is0.73mg/min in the heating rate of15℃/min. In the atomosphere of N2, the activation energy of KHCO3decomposition is between58.4-92.0kJ/mol, and the regeneration reaction activation energy of potassium based coal fired fly ash supported sorbent and potassium based zeolite molecular sieves supported sorbent are24.8-59.8kJ/mol and41.09-45.60kJ/mol. The optimum heating rate of potassium based zeolite molecular sieves supported sorbent regeneration reaction is10℃/min, its activation energy is less than KHCO3decomposition and more than potassium based coal fired fly ash supported sorbent regeneration reaction under certain conditions.Finally, on the premise of existing devices, the experiment device of potassium based sorbent regeneration reaction for CO2capture was designed, through the CO2concentration before and after the experiment device, study regeneration/absorption cycle characteristic, and provide some basic data and theoretical support to make it can be widely used in coal-fired power plant.