Potassium Catalytic Effect on Gasification Reactions of Coal and Coal/Biomass Blends under Oxy-combustion Conditions. An Isotopic Study Using ¹³C¹⁸O₂

Abstract

In the present study, 20 wt % K 2 CO 3 was added to coal and coal/biomass blends in 20:80 wt % ratio and subsequently were heating-treated at 600 °C using CO 2 or N 2 atmospheres.The reactivity under oxy-combustion conditions (21 % O 2 + 79 % CO 2 ) was studied by thermogravimetry, and characterization of chars was carried out by N 2 adsorption, scanning electron microscopy, Raman and X-ray photoelectron spectroscopy. It was observed higher activation energy for impregnated coal/biomass blends compared to impregnated coal, likewise, for materials thermally treated with CO 2 . It is demonstrated that CO 2 gasification takes place together with O 2 combustion under oxy-combustion conditions. Isotopic labelled 13 C 18 O 2 was used to confirm the participation of CO 2 gasification reactions at 450, 500, 550 and 600 ᵒ C in both catalyzed and uncatalyzed systems under O 2 + CO 2 . The catalytic effect of potassium promotes CO 2 gasification, and highest CO ( 12 C 18 O) desorption was obtained with impregnated samples. It is possible to suggest that CO 2 gasification reactions follow different reaction pathways in presence or absence of potassium. The catalytic gasification reaction proceeded preferentially through a molecular CO 2 ( 13 C 18 O 2 ) adsorption route while the non-catalyzed systems advanced using a dissociative adsorption pathway.

Raman Spectroscopy as a Versatile Tool for Investigating Thermochemical Processing of Coal, Biomass, and Wastes: Recent Advances and Future Perspectives

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Possible Options for Utilization of EU Biomass Waste: Pyrolysis Char, Calorific Value and Ash Content

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