Effect of MgCl2 loading on the evolution of reaction intermediates during cellulose fast pyrolysis at 325 °C

This study reports the effect of MgCl2 loading on the evolution of reaction intermediates during cellulose fast pyrolysis at 325 degrees C. The loading of MgCl2 significantly changes the reaction pathways of cellulose pyrolysis and enhances the cross-linking of hydroxyl groups to release water even during the heating-up stage, as a result of the weakened hydrogen bonding networks during both the wet impregnation and the heating processes. Such a highly cross-linked cellulose strongly affects the evolution of reaction intermediates during the subsequent isothermal pyrolysis at 325 degrees C, i.e., producing the water-soluble intermediates rich in cross-linked structures. The loading of MgCl2 may catalyse the interactions between the water-soluble and water-insoluble portions in pyrolysing cellulose, depending on the Mg distribution. Our results indicate that the water-insoluble Mg has a little effect on the pyrolysis of sugar structures in the water-insoluble portion, which still proceeds in a similar way as that of raw cellulose, i.e., dominantly via depolymerisation. Whereas the water-insoluble Mg has a strong catalytic effect on the pyrolysis of non-sugar structures in the water-insoluble portion into more condensed structures, leading to a high char yield from the pyrolysis of the MgCl2-loaded cellulose. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.