Some Innovative Readily Applicable Proposals for Chemical Separation and Sequestration of CO₂ Emissions From Power Plants

The goal of the present manuscript is the investigation of two novel systems for partial CO₂ capture from the exhausts of fossil fuelled powerplants. These systems should be relatively cheap and easily applicable to existing powerplants with minor modification, in order to make them accessible by a large range of users and favour a significant diffusion of partial CO₂ sequestration. Two basic processes were proposed: 1. Absorption with a liquid solution of water and NH₃; 2. Absorber/desorber system with a liquid solution of water and phosphates. In the first one, the exhausts react into an absorber column with a liquid sorbent, which is a solution of water and ammonia. The process sequestrates the CO₂ in carbammate and bicarbonate and the final product are salt of ammonia, i.e. ammonium carboamate (NH₄HCO₃) and ammonium bicarbonate (NH₄NH₂COO). The outgoing streams of this process are the exhaust gas with a reduced content of CO₂ and a secondary product formed by salts of ammonium, which have an interesting market potential as fertilizers. The obtained CO₂ reduction level was more than 40%, while the amount of secondary products is high enough to get it marketable. In the second process, the exhausts passing through an absorber column react with a liquid sorbent, which is a solution of water and sodium (or potassium) phosphate. The process sequestrates the CO₂ in bicarbonate ions by means of the ions phosphate and the outlet stream is a solution of water and phosphate and carbonate ions. This stream is collected in a desorbing column, where the phosphate ions are almost completely regenerated. The CO₂ reduction level is always higher than 20% and it can also reach very high values, depending on the parameters of process.