Sustainable nanoporous carbonaceous adsorbents for carbon dioxide capture

GOMEZ-DELGADO, E.; RODRIGUEZ-ORTIZ H.; NUNELL, G.V.; CUKIERMAN, A.L.; BONELLI, P.R.

Advances in Enveronmental Research

Nova Science Publishers

Lugar: New York; Año: 2022; p. 71 - 112

Adsorption ontonanoporous activated carbons arises as a sustainable, efficient, and versatilealternative to remove and capture CO2 from process gaseous streams,among current technologies. These adsorbents, obtained from lignocellulosicbiomass such as forestry, agricultural and agroindustrial residues, in additionto fulfill their function of capturing CO2, contribute to theabatement of emissions avoiding the accumulation of these residues andimmobilizing, with a high degree of mineralization, the carbon removed from theatmosphere during the life time of plant growth. The present chapter attemptsto get better insight about the relationship between the process variablesinvolved in activated carbons preparation and their CO2 removalperformance, trying to find the key features associated to the efficient CO2adsorption. The biomassic precursors employed were Parkinsonia aculeata wood sawdust, Pouteria sapota seeds, from the popular tropical fruit locallyknown as “mamey”, and cones from Pinuscanariensis evergreen tree. Chemical activation of the precursors employingKOH as activating agent was applied under pre-established experimentalconditions. For the cones, the influence of the impregnation ratio and thermaltreatment was additionally investigated. Chemical, textural and morphologicalcharacteristics of the adsorbents developed were evaluated in relation with thetype of precursor and experimental conditions applied. The resulting adsorbentsshowed well developed, predominantly microporous, structures withspecific surface areas ranging from 1000 to 2000 m2 g-1,as assessed by gas physisorption techniques. CO2 adsorptioncapacities mimicking post-combustion conditions, were evaluated fromthermogravimetric assays and experimental breakthrough curves obtained in apacked-bed column. The results indicated a good CO2 adsorptionperformance reaching values between 1 and 2 mmol of CO2 per gram ofadsorbent. Simulation of the breakthrough curves by well known models enabledto obtain data for the scale up and industrial application of these materialsto remove CO2 from post-combustion streams, thus supplying valuableinformation for designers of air purifying systems. Regeneration by thermaldesorption of the activated carbons studied was also assessed. The CO2removal capacity was not noticeably affected after five adsorption-desorptioncycles. The samples almost kept their initial CO2 adsorptioncapacity, pointing to their potential use as storage material and furtherutilization of the desorbed CO2.