https://doi.org/10.1016/j.ccst.2022.100096
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γ-Al2O3 spheres (Sasol, 1mm nominal diameter, Fig. 1a) were preliminarily washed in a dilute HNO3 water solution, rinsed with distilled water and finally calcined in air at 450 °C to remove residual basic compounds from their surface. Ru was dispersed onto this support by two consecutive incipient wetness impregnation cycles with a 0.167 M solution of Ru(III) nitrosyl nitrate (Aldrich), each followed by calcination in air at 350 °C for 1h, and final reduction in H2 (20% in N2) at 450 °C for 2h (reference sample: RuA). Thereafter, the sorbent phase was added to the RuA catalyst by incipient impregnation with an aqueous solution of LiNO3 (2 cycles), followed by drying at 120 °C in air and reduction in H2 (20% in N2) at 450 °C for 2h. The nominal loadings of Li and Ru in the resulting DFM were 3% and 0.95% wt., respectively. Two reference samples were prepared by impregnating the same γ-Al2O3 spheres with water solutions of LiNO3 or Li2SO4, followed by drying at 120 °C.
Fig. 1. (a) Optical images of spherical γ-Al2O3 support and blade cut cross-sections of Li-RuA DFMs prepared with or without preliminary washing the support in acidic solution determining a homogeneous or an egg-shell distribution of Ru (black) within the spheres. (b) Weight change and corresponding emission trace of NO during the H2-reduction of LiNO3 impregnated on either RuA catalyst and bare Al2O3 support. (c) Pore Size Distribution analysis and (d) XRD patterns of the fresh reduced RuA and Li-RuA DFM and its aged form (S-Li-RuA) as recovered at the end of the prolonged tests of cyclic CO2 capture with SO2 and methanation. XRD Legend: ■ =Ru, ο =γ-Al2O3, * =Li2SO4, ● = LiAl5O8
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