Integration of CO2 Capture and Mineral Carbonation by Using Recyclable Ammonium Salts

Abstract

A new approach to capture and store CO₂ by mineral carbonation using recyclable ammonium salts was studied. This process integrates CO₂ capture with mineral carbonation by employing NH₃, NH₄HSO₄, and NH₄HCO₃ in the capture, mineral dissolution, and carbonation steps, respectively. NH₄HSO₄ and NH₃ can then be regenerated by thermal decomposition of (NH₄)₂SO₄. The use of NH₄HCO₃ as the source of CO₂ can avoid desorption and compression of CO₂. The mass ratio of Mg/NH₄HCO₃/NH₃ is the key factor controlling carbonation and the optimum ratio of 1:4:2 gives a conversion of Mg ions to hydromagnesite of 95.5 %. Thermogravimetric analysis studies indicated that the regeneration efficiency of NH₄HSO₄ and NH₃ in this process is 95 %. The mass balance of the process shows that about 2.63 tonnes of serpentine, 0.12 tonnes of NH₄HSO₄, 7.48 tonnes of NH₄HCO₃, and 0.04 tonnes of NH₃ are required to sequester 1 tonne of CO₂ as hydromagnesite.