A new honeycomb carbon monolith for CO2 capture by rapid temperature swing adsorption using steam regeneration

Abstract

A rapid process for CO2 capture is of key importance for the economic feasibility of the process in industry, consequently short adsorption/desorption cycles are crucial. With this aim in mind, a carbon based honeycomb monolith was evaluated for CO2 capture in a thermal swing adsorption process at short contact times. The effect of (1) regeneration time, (2) presence of water vapor during adsorption and desorption and (3) regeneration method (steam versus hot air) on CO2 adsorption was studied. The monolith was characterized in terms of porosity and CO2, N2, and H2O isotherms. Cyclic adsorption/desorption experiments were performed using different synthetic gas mixtures with concentrations of CO2 ranging between 6 and 15 vol%. The effect of water vapor in the synthetic gas mixture on adsorption capacity was limited but increases with relative humidity. Steam of 120 °C was used to heat the monolith and desorb CO2. Advantages of steam usage are the facile separation of steam and concentrated CO2 and the low (waste) heating energy cost of steam. It was demonstrated that the steam allows very fast heating and cooling of the monolith. However, the presence of residual condensation water after the cooling step reduces the cyclic adsorption capacity, requiring an additional drying step with hot or cold air.