氨水混合吸收剂脱除CO2实验研究

氨水作为一种很有应用前景的CO2化学吸收剂,存在吸收速率慢的问题.使用湿壁塔实验台,考察了不同种类的添加剂(MEA、PZ、1-MPZ、2-MPZ)对氨水吸收CO2速率的影响.结果表明,4种添加剂均能明显提高氨水吸收CO2的速率,其中PZ具有最好的促进效果.0、0.1、0.3和0.5 mol·mol-1负荷下,3 mol·L-1NH3+0.3 mol·L-1PZ溶液的总传质系数(KG)分别是3 mol·L-1NH3溶液在相应负荷下的3、3.2、3.2和2.9倍.改变反应温度、添加剂量、PZ浓度等条件对基于NH3/PZ混合吸收剂吸收CO2的反应过程进行实验,得到了其在不同条件下的KG,初步探讨CO2吸收的反应机制,并计算出准一级反应速率常数为42.7 m3·(mol·s)-1.

Experimental Study on CO2 Absorption by Aqueous Ammonia-based Blended Absorbent

A crucial problem for the promising absorbent aqueous ammonia (NH₃) is the low CO₂ absorption rate. The mass transfer coefficient (K_G) of CO₂ in aqueous NH₃-based absorbents on a wetted wall column facility was investigated. Monoethanolamine (MEA), piperazine (PZ), 1-methyl piperazine (1-MPZ) and 2-methyl piperazine (2-MPZ) were introduced into NH₃ solutions as additives, all of which significantly increased the mass transfer coefficient of CO₂ in the solutions. With CO₂ loading of 0, 0.1, 0.3, 0.5 mol·mol^-1, K_G of 3 mol·L^-1 NH₃+0.3 mol·L^-1 PZ blended solution increased by 2, 2.2, 2.2, and 1.9 fold as compared to that of 3 mol·L^-1 NH₃. Typically, PZ, the additive with best performance, was chosen for further study. The effects of temperature and PZ concentration on CO₂ absorption in PZ solution and the blended NH₃/PZ solution. The calculated pseudo first order rate constant 42.7 m³·(mol·s)^-1] was analyzed to further elucidate the reaction mechanism in the blended NH₃/PZ solution.