Influence of the carbonization atmosphere on the development of highly microporous adsorbents tailored to CO2 capture

GOMEZ-DELGADO, EDWARD; NUNELL, GISEL; BONELLI P. R.; CUKIERMAN A. L.

JOURNAL OF THE ENERGY INSTITUTE

MANEY PUBLISHING

Año: 2022

1743-9671

Two microporous activated carbons (ACs) tailored to CO2 capture were developedfrom Prosopis ruscifolia sawdust. The ACs were obtained through a two-stage process.The first consisted in the carbonization of the precursor, while the second involvedchemical activation employing KOH solution as activating agent. The influence of theatmosphere involved in the carbonization stage (N2 flow at 773 K or air flow at 573 K)on the chemical and textural-morphological characteristics of the resulting ACs and ontheir CO2 removal capacity was analyzed. The ACs presented similar properties with apredominance of microporous structures, BET surface areas slightly larger than 1000 m2 g-1, and micropore volumes of ~0.43 cm3 g-1 on average. Both ACs also showeda predominance of surface acidic functionalities over basic ones. The adsorbedamounts of CO2 as determined from the isotherms were 5.6 and 5.3 cm3 g-1, for theACs developed from the precursor carbonized under N2 and air flow, respectively.From thermogravimetric tests to assess adsorption kinetics, values of the CO2 removal(101.325 kPa and 303 K) reached at equilibrium conditions were 1.15 and 1.04 mmol g-1, respectively. Present results demonstrated that the carbonization atmosphere didnot have a pronounced effect on chemical and textural characteristics of the resultingACs and, consequently, on their CO2 adsorption capacity. Accordingly, the use of airinstead of N2 in the carbonization stage of the activation process may represent aninteresting alternative because of the lower operating temperature involved, leading toreduce energy consumption and operating costs without sensibly affecting ACsperformance.