Adsorption Capacity Enhancement by Activation with CO₂ of Monolithic Adsorbents Made of KOH-Activated Carbon and Polymer-Derived Binder

Abstract

Disc-shaped monoliths molded from KOH-activated carbon powder (AC) and novolac resin (N) or poly(furfuryl alhohol) (P) binder were activated with CO 2 to open an access to the microporosity that was blocked by the binder char. The variation in the porous texture of monoliths was characterized by the N 2 adsorption at 77 K and mercury porosimetry. The results show that using N allows the monoliths to be activated to a higher burnoff compared to P (30 vs 15 wt %) without noticeable loss of the integrity and mechanical strength. The increase in the surface area and micropore volume on activation is accompanied by a considerable development of meso-and macropores and a decrease in bulk density of monoliths. The behavior has been discussed as an effect of excessive reactivity to carbon dioxide of KOH-activated carbon compared to binder derived char. The preferential burnoff of accessible activated carbon particles limits the enhancement of volumetric storage capacity with activation progress of monolith. The maximum methane uptake of 10.7 mmol g −1 at 25 °C and 3.5 MPa was measured for the activated monolith made using novolac binder.

Enrichment of Ventilation Air Methane (VAM) with Carbon Fiber Composites

“…Monolithic carbons have an advantage over conventional granular carbon beds because the former has much higher thermal conductivity and better resistances to various environmental conditions than the latter, especially for thermal regeneration. 12,13 For a process level, one also needs to consider a flow resistance (i.e., pressure drop) through a fixed bed. Thus, the void volume and the adsorbent packing density in the bed can be limited to a certain level to minimize the pressure drop particularly in dealing with high volumetric flow applications such as VA.…”

“…Also, any solid adsorbents need to be in a certain form to be used for fixed bed applications. Monolithic carbons have an advantage over conventional granular carbon beds because the former has much higher thermal conductivity and better resistances to various environmental conditions than the latter, especially for thermal regeneration. , For a process level, one also needs to consider a flow resistance (i . e., pressure drop) through a fixed bed.…”

Postextraction Separation, On-Board Storage, and Catalytic Conversion of Methane in Natural Gas: A Review

“…Mohammed et al 461 reported high pressure (13.8 MPa) methane adsorption in five types of dry coal and one commercial activated carbon (F-400) and mathematically correlated the adsorption data with a simplified local density (SLD) model. Machnikowski et al 462 synthesized carbon monoliths from KOH activated carbon and CO 2 activated novolac resin with polyfurfural alcohol binder to perform high-pressure methane adsorption. The highest methane uptake was 10.7 mmol/g at 298 K and 3.5 MPa pressure.…”

Carbon-Based Adsorbents for Postcombustion CO2 Capture: A Critical Review

“…13,71,72,84 ■ ACTIVATED CARBON Activated carbon (AC) can also be derived from biomass through pyrolysis, but requires either physical or chemical activation. The feedstock of AC production can range from waste biomass, such as spent coffee grounds, 85 to nitrogen-rich chitosan, 86 to synthetic organic polymers, 87 to chicken feathers. 23 To prepare chemically activated carbon, it is necessary to introduce chemicals, such as acid, base, or salt to treat the feedstock biomass.…”