Developing hierarchically ultra-micro/mesoporous biocarbons for highly selective carbon dioxide adsorption

Activated olive mill waste-based hydrochars as selective adsorbents for CO2 capture under postcombustion conditions

“…From the results obtained, the authors highlighted the Vultra value obtained for the R7_2T_10PEI carbon sample, which had the highest ultra-microporosity (0.175 cm 3 /g) with a mono-modal pore size distribution centred at 0.37 nm (a value a bit higher than the dynamic diameter of CO2 molecules, 0.34 nm). Nevertheless, in spite of possessing similar values of Vultra than the reported by Liu et al [27] and Xu et al [11], the two samples studied here do not present CO2 uptakes so high as the values reported by these two authors in their works. This could be explained, as it was mentioned above, because of the high percentage of mesoporous presented by these materials.…”

“…As it can be seen, this value is especially high for the AC_HTC_KOH_5_700 (0,192 cm 3 g -1 ) and AC_HTC _ZN_700_CO2_1 (0,198 cm 3 g -1 ) samples. Some previous works [2,4,5,8,27] reported high values of ultra-micropore volume (also estimated using DFT or NLDFT methods) for the ACs studied (up to 0.148 cm 3 g -1 ) but it was not until recently that Xu et al [11] and Liu et al [27] found values so elevated as the showed by these two hydrochars investigated in this work. Xu et al [11] obtained, using a DFT-based model, values of Vultra between 0.171 and 0.209 cm 3 g -1 for camphor leaves chemically activated with KOH at different temperatures.…”

“…All the activated carbons studied by Xu et al [11] showed a very strong peak at 0.6 nm, which would explain the higher CO2 uptake showed by these materials comparing with the works previously mentioned and the hydrochars studied here. On the other hand, Liu et al [27] studied dried rice husk samples pre-oxidized and impregnated with KOH, which were compacted at different pressures. From the results obtained, the authors highlighted the Vultra value obtained for the R7_2T_10PEI carbon sample, which had the highest ultra-microporosity (0.175 cm 3 /g) with a mono-modal pore size distribution centred at 0.37 nm (a value a bit higher than the dynamic diameter of CO2 molecules, 0.34 nm).…”

The potential of biocarbon as CO2 adsorbent in VPSA unit

“…The method of post-combustion CO 2 capture includes absorption by aqueous solutions, adsorption by solid materials and membrane separation. Among them, the adsorption method is advantageous due to the low energy consumption and easy regeneration of the adsorbent, without producing adverse by-products or contaminated sorbents [4][5][6][7]. Activated carbon, zeolites and metal-organic frameworks (MOFs) are carbon dioxide capture adsorbents described in the literature [8][9][10][11][12][13][14].…”

Mesocellular silica foam supported polyamine adsorbents for dry CO2 scrubbing: Performance of single versus blended polyamines for impregnation

“…Among many adsorbents currently under development, amine functionalized solid adsorbents [11] are well recognised as being a class of adsorbents outperforming virtually any other solid adsorbents (e.g. zeolite [12], MOFs [13] and carbon based adsorbents [14][15][16] in many important aspects, such as their favourable operating temperature windows of 50-80°C, high CO2 adsorption capacity and selectivity and fast adsorption rate at low CO2 partial pressures (<15% v/v), which are the key requisites of capture materials recommended by the CCIC report. It has been reported that a solid adsorbent looping CO2 capture process, which can be easily facilitated either with circulating fluidised bed or dual fluidised bed technologies, is able to provide breakthrough energy cost reductions of 30-50% or more compared to advanced solvent systems [17].…”