Preparation and CO2 adsorption properties of soft-templated mesoporous carbons derived from chestnut tannin precursors

Abstract

This work presents a soft templating approach for mesoporous carbon using the polyphenolic heterogeneous biomass, chestnut tannin, as the carbon precursor. By varying synthesis parameters such as tannin:surfactant ratio, cross-linker, reaction time and acid catalyst, the pore structure could be controllably modulated from lamellar to a more ordered hexagonal array. Carbonization at 600 °C under nitrogen produced a bimodal micro-mesoporous carbonaceous material exhibiting enhanced hydrogen bonding with the soft template, similar to that shown by soft-templating of phenolic-formaldehyde resins, allowing for a tailorable pore size. By utilizing the acidic nature of chestnut tannin (i.e. gallic and ellagic acid), hexagonal-type mesostructures were formed without the use of an acid catalyst. The porous carbon materials were activated with ammonia to increase the available surface area and incorporate nitrogen-containing functionality which led to a maximum CO 2 adsorption capacity at 1 bar of 3.44 mmol/g and 2.27 mmol/g at 0 ºC and 25 ºC, respectively. The ammonia-activated carbon exhibited multiple peaks in the adsorption energy distribution which indicates heterogeneity of adsorption sites for CO 2 capture.

One‐stage Template‐free KOH Activation for Mesopore‐enriched Carbons and Their Application in CO2 Capture

“…The adsorption isotherms are presented in the Figure , which shows the capacity for M‐CAC 600–1 at 1 atm is 2.3 and 3.4 mmol/g at 25 and 0°C, respectively. This result is competitive with that of other reported mesoporous carbon materials, for example, mesoporous carbon (2.73 mmol/gat 298 K and 1 bar) and nitrogen‐doped mesoporous carbon (2.43 mmol/g at 25°C and 1 bar) produced by Sun et al ., soft‐templated mesoporous carbons obtained by Dai and his group (2.27 mmol/g at 25°C and 1 bar), ordered mesoporous graphitic carbon prepared by Cui's group (57.2 mg/g 75°C and 1 atm), and N‐doped mesoporous carbon obtained by NaNH 2 by Dai's group (6.31 mmol/g at 1 bar and 2.06 mmol/g at 0.15 bar, at 25°C) . The adsorption capacity of CO 2 on porous carbons could be related to a complex interplay between surface area, pore size, pore distribution, pore morphology, and the presence of functional groups, which would affect the energy distribution of adsorption, ultimately determining the adsorption capacity of CO 2 .…”

“…However, mostly the pore structure of these activated carbons, as seen from previous research reports, tends to be dominated by micropores (<2 nm), which is not very appropriate for applications involving larger molecules and ions, for example, carbon electrodes for supercapacitors and batteries, chromatographic separation, catalyst support for fuel cells, adsorbents for polluted air or toxic dyes, and in biomedical engineering . For these and similar applications, recently, the design and synthesis of activated carbon with not only high surface area but also considerable mesoporous structure (2–50 nm) have attracted high interest due to its wide range of pore sizes which can result in facilitating gas/ion transport and diffusion into micropores by reducing mass transfer resistance and diffusion distance …”

Adsorption–desorption of CO2 on zeolite-Y-templated carbon at various temperatures

“…This indicates that CO 2 adsorption occurs preferentially at a lower temperature. 3,[28][29][30] The CO 2 adsorption capacity at 30 C was higher than at the other two temperatures, due to physisorption and the fact that CO 2 adsorption on porous materials requires a matching of pore sizes. Since the PSD of the ZTC mainly consisted of micropores, it had a high CO 2 uptake due to pore matching with the CO 2 molecular size.…”

“…Most of them used pseudo-rst order, pseudo-second order and intra-particle diffusion models. 3,28,29 Therefore, in this paper, those models were used to explain the CO 2 adsorption mechanism in the carbon template zeolite based on its physical and chemical properties, to match the experimental data, and also to study the mass transport process.…”

Designing amino‐based ionic liquids for improved carbon capture: One amine binds two CO2

“…Some new materials for CO 2 capture, such as solid adsorbents, membranes, and ionic liquids (ILs) have been developed in the past few decades, which may be good alternatives to achieve good CO 2 separation. However, their low CO 2 adsorption capacity is one of the major challenges to commercialize.…”