Effect of microwave assisted solvothermal process parameters on carbon dioxide adsorption properties of microporous carbon materials

Abstract

In this work, production and characterization of carbon spheres from resorcinol and formaldehyde, using a microwave assisted solvothermal reactor, is presented. The influence of different experimental conditions, e.g., reaction time, pressure, and power, on the structure of the obtained materials, and carbon dioxide adsorption properties, was studied. Using the method described in this work, it is possible to significantly reduce the reaction time, to as low as 10 min, compared with widely described processes carried out in autoclaves, requiring several hours. Simultaneously, it was discovered that the application of higher reactor pressures, over 3 MPa, resulted in the destruction of spherical shape and the formation of graphitic layers. The importance of micropores below 0.4 nm, for adsorption of carbon dioxide, was also shown in this work. Microporous carbon spheres with efficient CO 2 adsorption properties (nearly 7 mmol/g at 1 bar and 0 °C) were synthesized using this process. Spherical shape collapse – effect on microporosity characteristics and CO 2 adsorption. • The effect of synthesis conditions of carbon spheres on their adsorption properties towards carbon dioxide were studied. • An increase of synthesis pressure from 10 to 40 atm caused a collapse of spherical shape and graphitization of the material. • An accompagnying dissappearence of micropores below 0.4 nm was observed, negatively influencing CO 2 physisorption. • Simultaneously, a positive effect for CO 2 chemisorption at 25 °C was obsserved, thanks to an increase in micropores of 0.5 nm.