Highly Porous Carbons Synthesized from Tannic Acid via a Combined Mechanochemical Salt-Templating and Mild Activation Strategy

Abstract

Highly porous activated carbons were synthesized via the mechanochemical salt-templating method using both sustainable precursors and sustainable chemical activators. Tannic acid is a polyphenolic compound derived from biomass, which, together with urea, can serve as a low-cost, environmentally friendly precursor for the preparation of efficient N-doped carbons. The use of various organic and inorganic salts as activating agents afforded carbons with diverse structural and physicochemical characteristics, e.g., their specific surface areas ranged from 1190 m2·g−1 to 3060 m2·g−1. Coupling the salt-templating method and chemical activation with potassium oxalate appeared to be an efficient strategy for the synthesis of a highly porous carbon with a specific surface area of 3060 m2·g−1, a large total pore volume of 3.07 cm3·g−1 and high H2 and CO2 adsorption capacities of 13.2 mmol·g−1 at −196 °C and 4.7 mmol·g−1 at 0 °C, respectively. The most microporous carbon from the series exhibited a CO2 uptake capacity as high as 6.4 mmol·g−1 at 1 bar and 0 °C. Moreover, these samples showed exceptionally high thermal stability. Such activated carbons obtained from readily available sustainable precursors and activators are attractive for several applications in adsorption and catalysis.

Chemical Activation of Lignocellulosic Precursors and Residues: What Else to Consider?

“…A very interesting approach, from an environmental point of view, has been presented by Nowrouzi et al, dealing with KOH activation of a water tissue in a process with zero liquid effluents discharge [ 95 ]. Recently, Głowniak et al have paid attention to the preparation of activated carbons using a green precursor (i.e., tannic acid) and a cheap activating agent based on a mixture of NaCl and ZnCl 2 , synthesizing activated carbons with surface areas ranging 1190–3060 m 2 /g [ 157 ].…”

Scale‐Up of Solvent‐Free, Mechanochemical Precursor Synthesis for Nanoporous Carbon Materials via Extrusion

“…Nanoporous carbons (NC) play a key role in air and water purification to scrub toxins and greenhouse gases from the environment [1] . They are suitable as catalysts or catalyst supports, for gas sorption and separation, and in energy storage devices like supercapacitors, fuel cells, or batteries [2,3,4] …”

“…[1] They are suitable as catalysts or catalyst supports, for gas sorption and separation, and in energy storage devices like supercapacitors, fuel cells, or batteries. [2,3,4] Most industrially relevant syntheses rely on either the physical or chemical activation of organic compounds such as coconut shells, lignin, or rice husks. [3,5] Due to lower control over the surface, pore structure, and impurities, their performance in most applications (e. g., electrochemical energy storage) is lower than that of tailored carbons obtained by templating, sol-gel chars, or other advanced synthesis techniques.…”

“…[2,3,4] Most industrially relevant syntheses rely on either the physical or chemical activation of organic compounds such as coconut shells, lignin, or rice husks. [3,5] Due to lower control over the surface, pore structure, and impurities, their performance in most applications (e. g., electrochemical energy storage) is lower than that of tailored carbons obtained by templating, sol-gel chars, or other advanced synthesis techniques. [6] To overcome these limitations there is a great need for tailoring the surface properties of NC by doping the carbon precursor with heteroatoms, adding hierarchical pore architecture, or controlling the carbonization degree to increase their desired performances.…”

Synthesis of Porous Carbon for Acetone Adsorption: Specific Surface Area, Porous Structure and Oxygen Functional Groups

“…The tannic acidderived porous carbon with large surface area (1190-3060 m 2 g À 1 ) showed excellent CO 2 and H 2 adsorption performance, and sustainable inorganic and organic salts are employed as templates and activators in the study. [14] Among them, potassium citrate is one kind of cheap and readily available organic salt. Luo et al [15] prepared carbon networks by loading the potassium citrate onto poplar catkin for carbonization at different temperatures, containing macropores, small mesopores and micropores.…”