Carbon adsorbents for CO2 capture from bio-hydrogen and biogas streams: Breakthrough adsorption study

Abstract

The biological production of H 2 by dark fermentation is being extensively investigated due to the great potential of the two-phase hydrogen/methane fermentation process for recovering energy from carbohydrate-rich wastes. However, the purification of the bio-hydrogen and biogas obtained is needed to produce high-purity H 2 and CH 4 streams appropriate for industrial application. In this study, the performance of three activated carbons (No1KCla-600, No1KClb-1000 and No2OS-1000), synthesized from phenol-formaldehyde resins, as potential adsorbents for CO 2 capture from bio-hydrogen and biogas streams has been evaluated under dynamic conditions. Adsorptiondesorption cycles by means of temperature swings were conducted at ambient temperature and atmospheric pressure with CO 2 /H 2 (40/60 and 70/30 vol.% at normal conditions) and CO 2 /CH 4 (50/50 vol.% at normal conditions) binary gas mixtures in a purpose-built fixed-bed set-up. The performance of the resin-derived carbons to separate CO 2 was superior to that of reference commercial carbons in terms of CO 2 uptake, breakthrough time and column efficiency. These adsorbents presented high * Corresponding author.

Kinetics of CO2 adsorption on cherry stone-based carbons in CO2/CH4 separations

“…It is therefore a microporous activated carbon with suitable characteristics for CO 2 adsorption. More details about its chemical and textural characteristics can be found elsewhere [20,25]. Textural parameters of the cherry stone-based carbons and Calgon BPL that may be relevant for discussion are summarized in Table 1.…”

“…The equilibrium adsorption capacities of CO 2 and CH 4 were determined by applying a mass balance to the bed as well as accounting for the gas accumulated in intraparticle voids and dead space. Detailed description can be found in Gil et al [25] and in Appendix A. The breakthrough times were taken at a relative concentration (C i,outlet /C i,feed ) of 0.05.…”

“…To calculate the total porosity of the bed we took into account the packed bed porosity and the particle porosity [25]. It should also be pointed out that a similar bed height was established in all the breakthrough experiments.…”

Preparation and Evaluation of a Coconut Shell-Based Activated Carbon for CO2/CH4 Separation

“…The raw CNS was introduced in a quartz jacketed reactor and then placed in the vertical tubular kiln. The experimental set-up has been described elsewhere [34].…”

“…Breakthrough time, t b , defined as the time required for the detection of CO 2 at the exit of the column, and the adsorption capacity of CO 2 at equilibrium, were calculated as the average of the values obtained from the six successive cycles [34].…”