Molecular Modeling Study of the SO₂Deactivation of an Amine Resin and a Procedure to Avoid SO₂Deactivation Using a Polyethylene Glycol/Tertiary Amine System

Abstract

Since 2012, the polymeric resin Lewatit R VP OC 1065 has been investigated for removal of CO2 from various process streams and air. The present article focuses on the deactivation mechanism of the resin with SO2 and a work around. This is important for CO2 capture from flue gas of coal-fired power plants and fuel oil. The deactivation of the resin was already experimentally observed in 2013 but thus far not described computationally. Molecular modeling shows that Lewatit R VP OC 1065 is deactivated by irreversible formation of dimeric amine-SO2 charge-transfer complexes which are very stable and resist thermal and chemical desorption. Additional support for this view was found in the work on aminosilica adsorbents for CO2 capture, which are subject to SO2 deactivation also. Therefore, attention was paid to a procedure to avoid SO2 deactivation. Polyethylene glycol (PEG)/tertiary amine systems seem to be very promising. Their reported high SO2/CO2 selectivities, SO2 capacities, and ease of regeneration were computationally confirmed by identifying their mode of action and favorable thermodynamics. As a result, a combination of a PEG/tertiary amine system with Lewatit R VP OC 1065 might be a very attractive candidate two-step process to capture both SO2 and CO2 from flue gas originating from coal-fired power plants and large ships.