Improving the gas–solids contact efficiency in a fluidized bed of CO2 adsorbent fine particles

Abstract

A modified CO(2) adsorbent is obtained by dry mixing of a Ca(OH)(2) fine powder as received with a commercial silica nanopowder. Silica nanoparticles form light agglomerates of size of the order of tens of microns, which are uniformly fluidizable. These agglomerates act as dispersants of the Ca(OH)(2) fine particles, which coat the nanoparticle agglomerates likely due to contact charging. Ca(OH)(2) particles (CO(2) adsorbent) are thus provided with a vehicle for uniform fluidization. In this way, the contact efficiency between the CO(2) adsorbent and CO(2) in the fluidized bed is greatly enhanced. Experimental results show that the improvement of Ca(OH)(2) fluidizability serves to enhance the carbonation reaction in the fluidized bed.

Fluidization of nanopowders: a review

“…Alternatively, silica nanopowder can be mixed with calcium hydroxide fine powder to enhance the efficiency of CO 2 adsorption by improving the gas–solids contact efficiency in a fluidized bed (Valverde et al 2011). In this case, uniformly fluidizable agglomerates of silica NPs serve as carriers of Geldart C particles with high CO 2 adsorption capacity.…”

HCl absorption by CaO/Ca 3 Al 2 O 6 sorbent from CO 2 capture cycles using calcium looping

“…The development of some novel methods of modifying calcium-based sorbents and synthesizing new ones with enhanced CO 2 capture capacity, thermal stability, and mechanical strength is a strong active area of research [6,11,12]. The synthetic sorbents prepared from CaO and Al 2 O 3 precursors under different conditions exhibited a significant enhancement in CO 2 capture durability, sintering resistance, and pore structure in the calcium looping cycles [17][18][19][20][21][22][23][24][25][26].…”

“…Lots of methods have been developed to enhance the cyclic CO 2 capture capacity of calcium-based sorbents, minimize their loss in CO 2 capture capacity, increase the sintering resistance, and promote their mechanical stability in the multiple CO 2 capture cycles using calcium looping [12][13][14][15][16]. The criterion for the CO 2 sorbent design is to increase active surface area, pore structure stability, and mechanical stability of the sorbent, which would increase CO 2 capture capacity of the sorbent.…”

“…Martavaltzi and Lemionidou [18] used Ca(CH 3 COOH) 2 , Al(NO 3 ) 3 ·9H 2 O, and 2-propanol water solution by mixing method to synthesize a CaO/Ca 12 Al 14 O 33 sorbent through calcination at 900°C. Wu et al [19] mixed nano CaCO 3 , aluminum sol, and sodium hexametaphosphate together to prepare nano CaO/Ca 12 Carbide slag which is mainly composed of Ca(OH) 2 , is a by-product of the PVC production process and is always discharged from the chlor-alkali plants as an industrial solid waste. Li et al [27,28] found that carbide slag showed a good CO 2 capture performance in the calcium looping cycles.…”

“…The synthetic sorbents prepared from CaO and Al 2 O 3 precursors under different conditions exhibited a significant enhancement in CO 2 capture durability, sintering resistance, and pore structure in the calcium looping cycles [17][18][19][20][21][22][23][24][25][26]. The synthetic sorbents were composed of CaO and inert supporters (calcium aluminates) such as Ca 12 Al 14 O 33 [17][18][19][20], Ca 9 Al 6 O 18 [21][22][23], Ca 3 Al 2 O 6 [24], and Ca 3 Al 10 O 18 [15]. The difference in inert supporters depended on not only the calcium and aluminum precursors but also the synthetic methods.…”