Influence of minerals’ nature and concentration on the gasification of cypress wood sawdust chars Simona Bennici 1,2 , Lionel Limousy 1,2 , Khouloud Haddad 1,2 , Mejdi Jeguirim 1,2 1 Université de Haute-alsace, CNRS, IS2M UMR 7361, F-68100 Mulhouse, France 2 Université de Strasbourg, France Keywords: gasification; char, inorganics, biomass conversion. Presenting author email: simona.bennici@uha.fr Introduction The recent bio-based economy directions and the necessity to develop the use of renewable energy, in order to decrease the greenhouse emissions, results in an overwhelming compulsion to identify new and more environmental friendly biomass conversion processes. Thermo-chemical processes as combustion, gasification and pyrolysis are promising way to valorise biomass wastes by producing energy and added-values chemical products (McKendry, 2002), but many drawbacks have to been solved for widening their application. The operating temperature, the type of gasifying agent and its concentration, the biomass morphology and composition can strongly impact the reactivity. The presence of alkaline and alkaline earth metals (AAEM) has an effect on the kinetics of the char gasification reaction. For this reasons chars enriched with Na, K, Mg and Ca- salts have been testes in gasification to correlate the conversion performances to the presence of the different elements. Results The lignocellulosic raw material used to prepare the chars was constituted of washed cypress wood sawdust (CWS). Previous to pyrolysis (carried out at 5°C/min, under 100 mL/min N2 flow up to 800°C), different salts (CaCl2, MgCl2, KCl, NaCl) were deposited by impregnation method on the washed biomass, as detailed by (Haddad et al., 2017). The composition and the morphological and structural properties of the parent biomass, the washed biomass (CWS), as well as those of the impregnated samples (Me-CWS), were investigated by complementary physico-chemical techniques: Raman Spectroscopy, MEB-EDX, XRF, N2, and CO2-adsorption isotherms (Table 1). Table 1. Physico-chemical characterisation data Sample N2-adsorption XRF analysis (wt%) Vptot (cm 3 /g) Vpmicro (cm 3 /g) BET SA (m 2 /g) K Ca Na Mg CS 0.199 0.176 482 0.160 0.302 0.095 0.089 CWS 0.231 0.204 482 0.048 0.355 0.023 0.073 Na-CWS 0.173 0.151 420 0.005 0.286 0.795 0.016 K-CWS 0.192 0.181 421 0.570 0.243 0.034 0.015 Mg-CWS 0.206 0.190 490 nd 0.184 nd 0.660 Ca-CWS 0.198 0.188 455 0.012 0.501 0.033 nd The objective of this work is to compare the kinetics of the gasification reaction performed under different concentration of CO2 and to evaluate the catalytic (for Na and K salts) or inhibitor (for Ca and Mg salts) effect of the different inorganic species, present in the chars used as solid reactant (Fig.1). For this purpose, gasification was performed in a thermogravimetry device (micro-samples) at 800°C under 100 mL/min of CO2/N2 (with CO2 concentration of 20, 50, and 100%v/v). If it is true that further investigation is needed to clarify the catalytic or inhibiting effect of inorganic species (with respect to their concentration, their distribution inside the char matrix, their nature, the char morphology and surface modification, ect…), the catalytic effect of alkaline-species (Na and K) is confirmed. The observed inhibiting effect of Ca- and Mg-species, even if clear for the samples investigated in the present research, need to be deeply analysed, in order to discern between the direct Mg and Ca-species impact from other effects, related to changes in the morphology (i.e. development of micro and ultramicroporosity) and in the inorganics dispersion in the carbon matrix. Sodium and potassium containing chars displayed, as expected, a catalytic effect on the gasification process, while the presence of calcium and magnesium dramatically slowed down the gasification kinetics.