CO2 gasification reactivity of biomass char: Catalytic influence of alkali, alkaline earth and transition metal salts

[Display omitted] •Effect of nitrate salts on CO2 gasification of pistachio nut shell char was studied.•Char gasification reactivity enhanced in the order of Na>Ca>Fe>K>Mg>raw char.•Highest catalytic reactivity was achieved with 5% Na loaded char.•Random pore model was the most suitable kinetic model to describe the reaction rate.•Activation energy of 5% Na loaded char was 53kJ/mol lower than un-catalyzed char. This study investigates the influence of alkali (Na, K), alkaline earth (Ca, Mg) and transition (Fe) metal nitrates on CO2 gasification reactivity of pistachio nut shell (PNS) char. The preliminary gasification experiments were performed in thermogravimetric analyzer (TGA) and the results showed considerable improvement in carbon conversion; Na-char>Ca-char>Fe-char>K-char>Mg-char>raw char. Based on TGA studies, NaNO3 (with loadings of 3–7wt%) was selected as the superior catalyst for further gasification studies in bench-scale reactor; the highest reactivity was devoted to 5wt% Na loaded char. The data acquired for gasification rate of catalyzed char were fitted with several kinetic models, among which, random pore model was adopted as the best model. Based on obtained gasification rate constant and using the Arrhenius plot, activation energy of 5wt% Na loaded char was calculated as 151.46kJ/mol which was 53kJ/mol lower than that of un-catalyzed char.