Response surface methodology as an efficient tool for optimizing carbon adsorbents for CO2 capture

Abstract

Phenol-formaldehyde resins and a low-cost biomass residue, olive stones (OS), were used to prepare five activated carbons for CO 2 separation at atmospheric pressure, i.e., in post-combustion processes or from biogas and bio-hydrogen streams. Two phenolformaldehyde resins were synthesized: Resol, obtained by using alkaline environment, and Novolac, synthesized in the presence of an acid catalyst. Carbon precursors were prepared by mixing both resins with KCl or by mixing the Novolac resin with OS. The precursors were carbonized under an inert atmosphere of N 2 at different temperatures.The last stage in the synthesis of the adsorbents involved physical activation with carbon dioxide, which was carried out at different temperatures and burn-off degrees.Response surface methodology (RSM) is proposed as a tool for rapidly optimizing the activation parameters in order to obtain the highest possible CO 2 capture capacity of activated carbons. The optimum values of activation temperature and burn-off degree that maximize CO 2 uptake by the activated carbons at 35 ºC and atmospheric pressure were obtained within the experimental region. A value of CO 2 adsorption capacity of 9.3 wt.% was achieved. Activated carbons derived from Novolac phenol-formaldehyde * Corresponding author. Tel.: +34 985 119 090; Fax: +34 985 297 662 E-mail address: cpevida@incar.csic.es (C. Pevida) 2 resin type and from OS showed great potential as adsorbents for CO 2 capture at atmospheric pressure.

Recent advances in utilization of biochar

“…Yan et al [49] developed carbon-encapsulated iron nanoparticles catalyst for the Fischer-Tropsch synthesis of biomass-derived syngas to liquid hydrocarbons. The catalyst was [39,40] synthesized by thermal treatment of iron-impregnated pine biochar at 1000 1C for 1 h. Biochar was obtained from a typical fast pyrolysis of pine wood and treated with HNO 3 to remove intrinsic ash and tar before impregnation. The Fischer-Tropsch synthesis results showed that the biochar-based iron nanoparticles catalyst had an efficiency of converting syngas into liquid hydrocarbons (CO conversion rate over 90% and liquid hydrocarbon selectivity as high as 70%), which is higher than other reported carbon supported iron catalysts for Fischer-Tropsch synthesis of syngas (2% to 88% CO conversion and 5% to 60% liquid hydrocarbon selectivity) [49].…”

Phenol-Formaldehyde Resin-Based Carbons for CO2 Separation at Sub-Atmospheric Pressures

“…Synthesis was conducted following two different routes, acid (hydrochloric acid, 37 wt% HCl solution) and basic (sodium hydroxide, NaOH) catalysis for the Novolac and the Resol resins, respectively. Details on the synthesis of the PF resins can be found elsewhere [18]. Carbon precursors were prepared from the aforementioned resins, and potassium chloride (KCl) was incorporated as inorganic additive.…”

“…Previous works carried out in our research group have demonstrated the relationship between the volume of narrow micropores of less than 0.7 nm and CO 2 uptake at atmospheric pressure [20]. Response surface methodology was performed to obtain the optimum conditions of activation with CO 2 that maximise CO 2 adsorption at atmospheric pressure for each precursor (details can be found in [18]). Activation with CO 2 was conducted in a tubular furnace with a CO 2 flowrate of 10 mL¨min´1.…”

Towards Bio-upgrading of Biogas: Biomass Waste-based Adsorbents

“…For the olive stones derived carbon (OS-AC) a conventional two-step procedure was pursued, including prior carbonization under inert atmosphere followed by activation in CO 2 . More details on the production of this sample can be found in a previous paper from our group [5]. It must be noted that this sample was produced by addition of a phenol-formaldehyde resin to the olive stones prior to carbonization and subsequent activation in CO 2 .…”