CO2 adsorbent pellets produced from pine sawdust: Effect of coal tar pitch addition

• Pine-pitch adsorbent pellets were produced with carbon yields up to 40 wt.%.
• The adsorbents present high CO2 adsorption capacity in post-combustion conditions.
• The adsorbents present fast adsorption kinetics.
• The composite adsorbents present superior mechanical resistance.
• Oxidation increases the carbon yield and improves the adsorption performance.

The main drawbacks of developing carbon adsorbents from pine sawdust, an abundant biomass feedstock, are the low carbon yield of the process and the poor mechanical properties of the resulting carbons. In an attempt to overcome these limitations, the effect of the addition of coal tar pitch was assessed. Adsorbent pellets were produced from pine sawdust and coal tar pitch by activation with CO2. The preparation process was optimized by using as decision variables the carbon yield and the adsorption performance of the adsorbents in conditions representative of post-combustion capture applications (10% CO2 at atmospheric pressure and at 50 °C). Subjecting the composite pellets to a pre-oxidation treatment with air increased the carbon yield of the production process, and also improved the adsorption kinetics and capacity of the final adsorbents. The prepared adsorbents present a high carbon yield, a superior mechanical resistance and a competitive adsorption performance.

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