Catalytic effect of alkali and alkaline earth metals on fast pyrolysis pre-treatment of agricultural waste

Abstract

The catalytic effect of mineral components (K, Ca, Mg and Na), after pre-treatment by water leaching and adding NaCl, was evaluated in fast pyrolysis with the biomass of four types of agricultural waste (olive pomace, nutshell, almond shell, and pistachio shell). Water leaching proved to be effective at reducing mineral content in the raw materials, especially in terms of removing K. As a consequence, there was lower decarboxylation activity during fast pyrolysis, and a lower yield of phenolic compounds was obtained. The effect of adding NaCl was evaluated by varying its ratio in the blend (1, 3 and 5 wt%) and it promoted cracking and dehydration reactions, favoring the formation of light molecular-weight compounds as carboxylic acids. © 2021 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.