Aleksey G. Okunev

CaO/Y2O3 pellets for reversible CO2 capture in sorption enhanced reforming process.

Abstract Pellets of a novel, high temperature CO2 sorbent, made of CaO-impregnated porous Y2O3, were prepared. Yttria pellets were synthesized from a mixture of yttria powder and a softener. A combination of ethylene glycol, used as a softener, and a casting method yielded mechanically stable pellets after calcination at 800ºC. Treatment of the Y2O3 support at higher temperatures further increases the pellets strength. The same effect of pellets strengthening was observed after yttria impregnation with CaO. Sorption capacity of the pellets with CaO content of 9 wt. %, measured at isothermal conditions of 740ºC, reaches 7.5 wt. % for shorter recarbonation time of 20 min and 8.5 wt. % for a longer time of 1 hour. In this respect, sorption properties of pelletized CaO/Y2O3 are similar to those of powdered material. A distinctive feature of the pelletized CaO/Y2O3 sorbent pretreated at high temperatures is the increase in capacity during the initial cycles.

Direct CO2 capture from ambient air by K2CO3/alumina composite sorbent for synthesis of renewable methane

Abstract nA composite sorbent was synthesized by impregnating cylindrical granules of mesoporous γ-Al2O3 with an aqueous solution of K2CO3. Three fractions of the composite with the

A Novel Process for Renewable Methane Production: Combining Direct Air Capture by K 2 CO 3 /Alumina Sorbent with CO 2 Methanation over Ru/Alumina Catalyst

CO2 methanation over supported ruthenium catalysts is considered to be a promising process for carbon capture and utilization and power-to-gas technologies. In this work 4% Ru/Al2O3 catalyst was synthesized by impregnation of the support with an aqueous solution of Ru(OH)Cl3, followed by liquid phase reduction using NaBH4 and gas phase activation using the stoichiometric mixture of CO2 and H2 (1:4). Kinetics of CO2 methanation reaction over the Ru/Al2O3 catalyst was studied in a perfectly mixed reactor at temperatures from 200 to 300xa0°C. The results showed that dependence of the specific activity of the catalyst on temperature followed the Arrhenius law. CO2 conversion to methane was shown to depend on temperature, water vapor pressure and CO2:H2 ratio in the gas mixture. The Ru/Al2O3 catalyst was later tested together with the K2CO3/Al2O3 composite sorbent in the novel direct air capture/methanation process, which combined in one reactor consecutive steps of CO2 adsorption from the air at room temperature and CO2 desorption/methanation in H2 flow at 300 or 350xa0°C. It was demonstrated that the amount of desorbed CO2 was practically the same for both temperatures used, while the total conversion of carbon dioxide to methane was 94.2–94.6% at 300xa0°C and 96.1–96.5% at 350xa0°C.