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Adsorption using bio‐based adsorbents has been pointed out as an economical and environmentally benign technology for CO₂ gas separation and storage. A bio‐based adsorbent can be fabricated from low‐cost worldwide available biomass feedstock and bio‐wastes from different industries (e.g., dairy manure, forestry, agriculture). As a result, it is a carbon rich material of hydrophobic nature, activated to gain high porosity development, and requires mild regeneration conditions. However, large‐scale deployment of bio‐based adsorption processes remains challenging. Our group has been intensively developing biomass‐based adsorbents in conjunction with the design of tailored CO₂ adsorption‐based cyclic processes for the envisioned application. Herein, key concepts on adsorption technology, biomass waste management, and different activation techniques for biomass‐based adsorbent precursors are discussed. This review addresses the most relevant studies in the literature, from lab experimentation on a milligram scale (volumetric and gravimetric tests) to dynamic tests in bench or large‐scale cyclic adsorption processes (i.e., pressure swing adsorption, temperature swing adsorption, vacuum swing adsorption). Therefore, the main target is to give a holistic view of the industrial applications where CO₂ separations with these materials are more suitable. Finally, concluding remarks and future perspectives of bio‐based adsorbents in carbon capture are presented. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

The Spanish CO SB 2 sb Technology Platform Association (PTECO2) was founded in 2006 by Spain's industrial sector, research and technology centres, and universities. Acknowledging the opportunity given by I Greenhouse Gases: Science and Technology i , this special issue gathers nine interesting papers featuring the activities of some of the members of PTECO2. Acknowledging the opportunity given by I Greenhouse Gases: Science and Technology i , this special issue gathers nine interesting papers featuring the activities of some of the members of PTECO2. [Extracted from the article]

Abstract: Activated carbons for adsorption of CO2 under flue gas conditions were prepared by means of hydrothermal carbonization (HTC) and subsequent CO2 activation of spent coffee grounds. The HTC of the samples consisted of their heating at moderate temperature with a high water content in autoclave. A preliminary screening concluded that 1:2 biomass/water ratio (spent coffee grounds as received) and no chemicals added during HTC with further activation in CO2 at 800°C for 1 h are suitable conditions to produce the CO2 adsorbents. In addition, the response surface methodology (RSM) successfully evaluated the combined effect of HTC temperature and dwell time, to maximize the CO2 capture capacity within the experimental region. Both the lowest temperature and dwell time (120°C, 3 h) resulted in the maximum CO2 capture capacity (2.95 wt.%). Two activated carbons (ACs) were then produced: one via hydrothermal carbonization optimized by means of response surface methodology (RSM) followed by CO2 activation (HC‐Co) and the other one by single‐step CO2 activation as described in the Group's patent ES2526259 (AC‐Co). Analysis of the features and performances of the two ACs revealed superior chemical and textural characteristics on HC‐Co for CO2 adsorption under post‐combustion capture conditions; HTC process is the sole responsible of this enhancement. Moreover, the proposed methodology to produce CO2 adsorbents from spent coffee grounds represents a more energy‐efficient approach. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A low-cost biomass, cherry stones (CS), was used as a carbon precursor to synthesize two activated carbons to be used for CO2/CH4 separation. Single-step activation with two activating agents, carbon dioxide and steam, was used. The activation conditions that maximize the CO2 adsorption capacity by the adsorbents at 25 ºC and atmospheric pressure were determined by response surface methodology (RSM). The optimum values were 885 ºC and 12% of solid yield when activating with carbon dioxide, but 850 ºC and 15.3% of solid yield when activating with steam. Heating rate did not show a significant effect on the CO2 uptake. CO2 adsorption capacity values up to 11.45 and 10.56 wt.% were achieved under such conditions using carbon dioxide and steam as activating agents, respectively. Carbon dioxide activation promoted the development of microporosity, whereas both micropores and mesopores were developed during steam activation. The CO2/CH4 separation performance at 3 bar of the optimum adsorbents indicated that both cherry-stones-based activated carbons could have great potential as CO2 adsorbents for CO2/CH4 separation. The adsorbent activated with carbon dioxide, CS-CO2, showed a slightly higher adsorption capacity, but the steam-activated sample, CS-H2O, had an enhanced selectivity to separate CO2 from CO2/CH4 binary mixtures. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

BACKGROUND Carbon materials are appealing adsorbents for postcombustion CO2 capture applications. In the present work, the adsorption of H2O, which is an abundant component in flue gases, and its influence on the adsorption of CO2 is evaluated using a microporous carbon. RESULTS The adsorption and desorption isotherms of H2O at 12.5, 25, 50, 70 and 85 °C were obtained for relative pressures between 0 and 0.95. The average isosteric heat of adsorption of H2O on PPC is 46 kJ mol−1. The equilibrium of adsorption and desorption of H2O on PPC can be reasonably well described by the DJD model over the entire temperature and pressure range evaluated. Breakthrough experiments carried out with synthetic flue gas showed that the adsorption of CO2 is not hindered by H2O at short adsorption times, relevant for the adsorption of CO2. Moreover, PPC can be fully regenerated recovering its full adsorption capacity after extended exposure to humid gas. CONCLUSIONS Although the adsorption capacity of CO2 can be reduced by the coadsorption of H2O, this effect only becomes significant at long adsorption times. By appropriately selecting the adsorption time in the cyclic process design the concentration of CO2 in the adsorbed phase can be maximized. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

High yield of high-purity H2 from acetic acid, a model compound of bio-oil obtained from the fast pyrolysis of biomass, was produced by sorption-enhanced steam reforming (SESR). An oxygen carrier was introduced into a chemical loop (CL) coupled to the cyclical SESR process to supply heat in situ for the endothermic sorbent regeneration to increase the energy efficiency of the process. A new multifunctional 1 %Pd/20 %Ni-20 %Co catalyst was developed for use both as oxygen carrier in the CL and as reforming catalyst in the SESR whereas a CaO-based material was used as CO2 sorbent. In the sorbent-air regeneration step, the Ni-Co atoms in the catalyst undergo strong exothermic oxidation reactions that provide heat for the CaO decarbonation. The addition of Pd to the Ni-Co catalyst makes the catalyst active throughout the whole SESR-CL cycle. Pd significantly promotes the reduction of Ni-Co oxides to metallic Ni-Co during the reforming stage, which avoids the need for a reduction step after regeneration. H2 yield above 90 % and H2 purity above 99.2 vol % were obtained. [ABSTRACT FROM AUTHOR]

The ignition behavior of coal and biomass blends was assessed in air and oxy-firing conditions in an entrained flow reactor. Four coals of different rank, an anthracite, a semi-anthracite, and two high-volatile bituminous coals, were tested in air and O2/CO2 (21-35% O2) environments. For all the coals, deterioration in ignition properties was observed in the 21%O2/79%CO2 atmosphere in comparison with air. However, the ignition properties were enhanced when the oxygen concentration in the O2/CO2 mixture was increased. Coal and biomass blends of a semi-anthracite and a high-volatile bituminous coal with 10 and 20 wt% of olive residue were also used in the ignition experiments under air and oxy-firing conditions. The ignition behavior of the coals improved as the additions of biomass increased both in air and oxy-firing conditions. In particular, the effect of biomass blending was more noticeable in the ignition of the high rank coal. Since industrial oxy-coal combustion with a wet recycle would result in higher concentrations of H2O(v), the effect of steam addition on ignition behavior was also studied. A worsening in ignition behavior was observed when steam was added to the oxy-fuel combustion atmospheres, although an increase in the steam concentration from 10 to 20% did not produce any significant difference in the ignition characteristics of the fuels. [ABSTRACT FROM AUTHOR]

The co-pyrolysis and co-gasification of binary blends of a bituminous coal (PT), a petcoke (PC) and two types of biomass (olive stones, OS; chestnut, CH) were studied at atmospheric pressure in a fixed bed reactor. The pyrolysis and gasification were performed under nitrogen, and steam/oxygen atmospheres, respectively. In a fixed bed reactor, the particles of the different fuels are in close contact, providing an optimum means for evaluating possible synergetic effects. Pyrolysis tests showed a lack of chemical interaction between the components of the blend. Therefore, the composition of the gas produced during the pyrolysis tests can be predicted from those of the individual components and their mass fractions. During the co-gasification tests, different interactions were observed depending on the heating rate. Low heating rates produced higher amount of CO and CO2, whereas tar yield decreased. At high heating rates, the biomass and coal blends produced more tar but less H2 and CO. The effect of co-gasification on apparent thermal efficiency was also evaluated. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]