Sorption-enhanced water gas shift reaction by sodium-promoted calcium oxides

Improving the stability of synthetic CaO-based CO 2 sorbents by structural promoters

“…Apart from post-combustion CO 2 capture, in-situ carbonate looping has also been investigated as means of process intensification in thermodynamically limited reactions, such as oxygenates reforming [27][28][29][30][31] and water-gas shift reaction [32][33][34][35]. Several theoretical [36,37] and experimental [38][39][40][41][42][43] studies on reforming of different fuels combined with CO 2 capture have shown that the addition of the CO 2 sorbent in the reformer shifts the equilibrium of the global reaction to the products' side, leading to increased H 2 efficiency and a CO 2 stream ready for sequestration in a single step, while operating at lower temperature than the conventional processes.…”

Load-following performance of IGCC with integrated CO2 capture using SEWGS pre-combustion technology

“…Several screening research studies have been conducted with the aim of identifying well-suited CO 2 adsorbent materials (Allam et al, 2005;Siriwardane et al, 2007;Reijers et al, 2006;Stevens et al, 2010;Choi et al, 2009;Martunus et al, 2011;Yong et al, 2002). A screening study was carried out on a number of candidate adsorbent materials including commercial sodium oxides (CL750), K 2 CO 3 -promoted hydrotalcites, lead oxide adsorbents (PbO), and double salt adsorbents (DS), to distinguish the most suitable adsorbent material for SEWGS application within the power plants for pre-combustion CO 2 capture.…”

“…This limits the selection of the adsorbent materials for the SEWGS process to those that can endure under high temperatures. However, the WGS reaction is slightly exothermic and is consequently promoted at low temperature (Stevens et al, 2010). Hence, there is a trade-off between the need for lower temperatures in favor of the WGS reaction and higher temperatures for the effluent gas entering the GT.…”

“…To improve properties of CaO materials for SEWGS application, novel CaO-based materials have been considered as CO 2 adsorbents. A NaOH-promoted CaO was developed in an experimental work for use in SEWGS reactors within IGCC plants (Siriwardane et al, 2007;Stevens et al, 2010). When CaO is promoted with NaOH, the CO 2 adsorption capacity is also improved.…”

Effect of CaO hydration and carbonation on the hydrogen production from sorption enhanced water gas shift reaction

“…Escobedo Bretado [9] used a quartz tube fixed-bed reactor to avoid the effect of steel reactor on the WGS and found that dolomite had catalytic action on the WGS and the chemical species responsible for the activity toward the WGS in calcined dolomite was possibly the MgO. From the thermodynamic point of view, Ca(OH) 2 may be formed in the SEWGS step with the presence of steam in gas phase with following reaction CaO þ H 2 O ¼ CaðOHÞ 2 DH 298 ¼ À65 kJ=mol (4) The carbonation of Ca(OH) 2 with CO 2 has been investigated recently by researchers aim to resolve the loss in CaO carrying capacity by the hydration of CaO [10e13], however, there is a significant difference between the carbonation reaction used for the CO 2 capture from flue gas and the SEWGS reaction, the knowledge of Ca(OH) 2 carbonation can not be directly used for the SEWGS reaction, and the effect of Ca(OH) 2 on the SEWGS reaction is not clear. At the same time, CaCO 3 product will be formed on the CaO surface during SEWGS reaction, it is reported that CaCO 3 product layer will increase the diffusion resistance and slow the carbonation rate [14e16], but there is less information from the literature concerning about the effect of CaCO 3 on the catalytic WGS reaction.…”