Facile CO2 diffusion for decarbonization through thermal insulation membranes

Abstract

It is hypothesized and demonstrated that thermal insulation membranes can provide an effective barrier to heat flow and simultaneously facilitate effective CO2 diffusion. Decarbonization technology often requires a CO2 concentration system, often based on amine binding or lime reaction, which is energy intensive and carries a high carbon footprint. Alternatively, C2CNT electrolytic molten carbonate decarbonization does not require CO2 pre-concentration and also provides a useful product (graphene nanocarbons) from the captured CO2.Here, a method of effective CO2 diffusion is demonstrated that simultaneously thermally insulates the decarbonization source gas from the high-temperature C2CNT system. Open pore, low-density, thermal insulations are implemented as membranes that facilitate effective CO2 diffusion for high-temperature decarbonization. Selected, high-temperature, strongly thermal insulating, silica composites are measured with porosities, ε, exceeding 0.9 (>90% porosity), and which display, as measured by SEM, large open channels facilitating CO2 diffusion. A derived and experimentally verified estimate for the CO2 diffusion constant through these membranes is DM-porous ​= ​ε3/2 DCO2, where DCO2 is the diffusion constant in air. DM-porous is applicable to a wide-range of CO2 concentrations both in the air and N2.The CO2 diffusion constant is translated to the equivalent decarbonization system mole influx of CO2 and shown capable of sustaining high rates of CO2 removal. Combined with the strong electrolyte affinity for CO2 compared to N2, O2, or H2O, the system comprises a framework for decarbonization without pre-concentration of CO2.