376979 Evaluation of Polyethylenimine Grafted and Polyallylamine Dendrimer Grafted Mesocellular Silica Foam Promoted By Surfactants for Post-Combustion CO2 Capture
Amino polymer-based adsorbents can significantly reduce the energy penalty for CO2 capture as compared to amine solutions and offer high CO2 capture capacities (>2 mmole per g adsorbent). However many amino polymers degrade at low temperatures of 90-110°C, which makes it difficult for desorption.
In this presentation, the technical issues associated with previously reported sorbents such as 1) thermal stability, 2) mechanical stability and 3) resistance to CO2 diffusion will be addressed. In this study, mesocellular silica foam (MCF) with a pore size range of 20-40 nm and a pore volume 1-2 cm3/g was synthesized. The control of silica substrate pore sizes is critical to keeping the CO2 diffusion resistance as small as possible. Adsorbents were synthesized using a double grafting method where anchor agents such as γ-chloropropyltrimethoxysilane help in covalent bond formation between poly-allylamine dendrimer, polyethylenimine and MCF. The thermal stability and CO2 capture capacities of the sorbent were found to increase by the adding a surfactant. The CO2 adsorption capacity obtained at 75°C for a surfactant promoted sorbent is 2.3 mmol of CO2/g adsorbent. The as-synthesized adsorbents with amino polymer (30-50% by weight) and surfactant (5-10% by weight) were evaluated for CO2 adsorption and desorption. The characterization of the fresh and spent sorbents using BET, SEM, TEM, FTIR, and TGA- will be presented.
An adsorption-desorption study was performed by temperature swing adsorption between 75-85°C using 99.9% CO2 gas and desorption at 90 °C in 100% N2 atmosphere using TGA-MS. For desorption, the pressure was reduced from 1 atm to 0.1 – 0.5 atm at 90°C to desorb 99% of the adsorbed CO2 gas. The equilibrium studies and cyclic performance results of the sorbents for 10 adsorption – desorption cycles will be presented.