Characteristics of as‐prepared biochar derived from catalytic pyrolysis within moderate‐temperature ionic liquid for CO₂ uptake

Abstract

A promising biochar as solid adsorbent for CO 2 uptake was prepared by the catalytic pyrolysis of coconut shell in moderate-temperature ionic liquid (IL). Then, it was characterized by means of SEM, EDS, BPEA, BET, NLDFT, FTIR, and TG-DSC, and a mechanism interpretation of the porous biochar formation was conducted. In addition, the adsorption characteristics of CO 2 on the asprepared biochar, such as adsorption capacity, adsorption potential, isosteric heat, and static selectivity at different adsorption temperatures and pressures, were systematically evaluated. The results indicated that the as-prepared biochar exhibited an adequate CO 2 adsorption with a capacity of 4.5 mmol/g at 273 K and 100 kPa. Then, a significant number of slit-like pores were revealed to exist on the as-prepared biochar with a peak pore size between a range of 0.6 nm-2 nm. The porous structure formation was ascribed to the release of carbon-, hydrogen-, oxygen-, sulphur-, and nitrogen-containing compounds during biochar preparation. Meanwhile, both the adsorption potential and isosteric heat of the CO 2 uptake under the tested conditions decreased with an increase in the adsorption capacity, which ranged from 33 kJ/mol-21 kJ/mol and 23 kJ/mol-7 kJ/mol, respectively. Therefore, the isosteric heat could be considered as a piecewise function of adsorption capacity. In addition, the molar ratios of CO 2 over N 2 adsorbed under the tested conditions were above 11 and were accompanied by molar ratio peaks of 26 at 273 K and 19 at 298 K, respectively. Moreover, an interesting phenomenon occurred: the static adsorptive selectivity of CO 2 over N 2 first increased and then decreased and there was an increase in the adsorption pressure at the tested adsorption temperatures. K E Y W O R D Sadsorption potential, biochar, CO 2 adsorption, isosteric heat, selectivity

Porous Structure of β-Cyclodextrin for CO2 Capture: Structural Remodeling by Thermal Activation

“…This indicates that thermal activation of β-CD is beneficial for promoting the capacity of CO 2 adsorption. The capacity on the β-CD derivative increases with an increase in adsorption pressure but decreases with increasing the adsorption temperature, just like the other carbon-based porous materials we prepared before [ 71 ]. This rule is also verified by adsorption capacity change of CO 2 on the derivative from β-CD activation at 800 °C (see Figure 7 b).…”

Hierarchical Porous Carbons Derived from Porous Biomass for High-Performance Capacitive Deionization

“…The average pore widths of LPC, SPC, and LSC were 54.7, 15.3, and 36.9 nm, respectively, and all belonged to the mesoporous range. The mesopores would provide adsorption channels for salt ions …”

Thermodynamics of CO2 adsorption on cellulose‐derived biochar prepared in ionic liquid

“…The procedures of biochar preparation and post‐treatment have been described in detail in our previous work. [ 33 ] Subsequently, CO 2 adsorption experiments at 273 K and 298 K were performed up to 102 kPa (current atmosphere pressure) based on the volumetric adsorption method, with the purpose of obtaining adsorption isotherms of CO 2 for thermodynamic analysis. Before the adsorption experiments, as‐prepared cellulose‐derived biochar (CCAc) (50 mg‐100 mg) was dried at 473 K for 8 hours.…”