Towards Bio-upgrading of Biogas: Biomass Waste-based Adsorbents

Abstract

The choice of an appropriate adsorbent for CO 2 separation by pressure swing adsorption remains a field of intense research and it would be of great help to rely on a parameter that could be used to quickly evaluate the performance of those materials. In this work, two activated carbons prepared in our laboratory from biomass wastes (olive and cherry stones) are studied for the separation of CO 2 from mixtures of CO 2 and CH 4 . CO 2 and CH 4 adsorption isotherms at room temperature and up to 10 bar were determined in a high pressure magnetic suspension balance. Breakthrough adsorption experiments with simulated biogas binary mixtures were conducted in a fixed-bed lab-pilot adsorption unit. The performance of the tested carbons was assessed in terms of a dimensionless sorbent selection parameter (S), which is based on the selectivity but incorporates the nature of the adsorption isotherm under PSA operating conditions. A commercial activated carbon Calgon BPL was also tested and used as reference material for the separation process. Experimental results show that the performance of the different adsorbents, based on the calculated S parameter, may be very different depending on whether data is derived from pure component adsorption isotherms or from breakthrough adsorption experiments. Under dynamic flow conditions, activated carbons produced in this study show a great potential to be applied to a CO 2 /CH 4 separation for biogas upgrading purposes. Further research is envisioned in order to define a PSA process that maximizes the purity and recovery of CH 4 .

Biogas purification by means of adsorption on pine sawdust-based activated carbon: Impact of water vapor

“…In addition, the concentration profile of both gases becomes steeper at higher feed flow rates as it can be observed in Figure 8. and pressures of 300 and 1000 kPa presented CO 2 uptakes between 2.53 and 5.12 mmol/g [36] while cherry stones-based activated carbon evaluated under similar conditions showed values of 2.80 and 5.14 mmol/g [35].…”

Biomass Valorization to Produce Porous Carbons: Applications in CO2 Capture and Biogas Upgrading to Biomethane—A Mini-Review

“…Upon this scenario, the use of porous biocarbons opens a double opportunity, in the sense that biomass turns to be a useful resource that can contribute, thereafter, to capture CO 2 and separate it from biogas, aiming to upgrade it to bio-CH 4 (Álvarez-Gutiérrez et al, 2014). This pathway closes the loop regarding carbon neutrality and contributes significantly to the field of renewable energy.…”

Biogas Purification: A Comparison of Adsorption Performance in D4 Siloxane Removal Between Commercial Activated Carbons and Waste Wood-Derived Char Using Isotherm Equations

“…Some studies considered the use of wastes in a biorefinery concept to produce fuels, power, heat, and value-added chemicals and materials, such as adsorbents. Gutierrez et al [35] activated biomass wastes (olive and cherry stones) to produce sorbents for the separation of CO 2 from biogas mixtures. Another study showed how ACs, produced by the physical and chemical activation of hydrothermally carbonized biomass (horse manure, grass cuttings, beer waste, and biosludge) have a strong ability to adsorb CO 2 [36].…”