Production of microporous biochars by single-step oxidation: Effect of activation conditions on CO2 capture

Abstract

1 1 2 3 4 5 AbstractThere is an urgent need to develop materials and processes that reduce the energy penalty 6 associated to the CO 2 capture step. Biochars are appealing adsorbents for post-combustion 7 CO 2 capture applications due to their low cost, stability in moisture conditions and 8 microporous nature. Series of carbon adsorbents were prepared from almond shells and olive stones by single-step activation with air at 400-500 ˚C, and with lower O 2 concentration in the activating gas, 3-5%, at higher temperatures (500-650 ˚C). This process entails energy savings compared to conventional activation with carbon dioxide or steam. It has been found that the pore size distribution can be tailored by adequately selecting the activating conditions.Carbons obtained under lower oxygen partial pressures and higher temperatures present narrow microporosity, which is essential for the adsorption of CO 2 at low partial pressures.These appealing low-cost adsorbents have competitive CO 2 working capacities and high CO 2 /N 2 equilibrium selectivity in conditions that can be considered representative for post-combustion CO 2 capture, thus showing potential for this application.

Green coffee based CO2 adsorbent with high performance in postcombustion conditions

“…Our group has explored the potential of different biomass sources as carbon precursors to develop CO 2 adsorbents: sewage sludge, almond shells, olive stones and more recently, coffee grounds [19,[32][33][34][35][36][37][38][39]. The latter is an abundant residue from the food industry: in 2012, 142 million bags of coffee were consumed, which represents an annual average growth rate of 2.4% over the period 2009-2012 [40], and on average, for each ton of green coffee, 650 kg of spent coffee is generated.…”

CO 2 adsorbent pellets produced from pine sawdust: Effect of coal tar pitch addition

“…Carbon adsorbents developed from different agricultural and food industry residues have shown potential as adsorbents for CO 2 capture applications [3][4][5][6][7][8][9][10][11][12][13]. These materials present the added advantage that they have fixed atmospheric carbon during their growth, reducing the carbon footprint of the final material.…”

Preparation and Evaluation of a Coconut Shell-Based Activated Carbon for CO2/CH4 Separation

“…The adsorption capacity of CO 2 of the synthetized activated carbon was tested in a TGA 92 thermogravimetric analyzer from Setaram following the procedure described elsewhere [35].…”