Revealing the chemistry of biomass pyrolysis by means of tunable synchrotron photoionisation-mass spectrometry

Abstract

Imaging'' biomass conversion: pyrolysis is the first reaction involved in all thermal processes for biofuels and green chemicals production. Synchrotron light ionisation and mass spectrometry is used for the first time to investigate biomass pyrolysis. The soft and tunable ionisation source coupled with ab initio calculations reveals chemical mechanisms and new major intermediate species. This methodology could be extended to the thermal and catalytic conversion of all other materials. Primary volatile products are analysed online as a function of photon energy, biomass composition (cellulose, xylan, lignin), reactor temperature and time of conversion. Hydroxyacetaldehyde was detected at very minor yields for cellulose pyrolysis confirming that it is a secondary product. The effect of cellulose structure and ash content on primary tar formation was also studied. The mechanism of levoglucosan dissociative photoionisation is depicted. A new major intermediate product which could be a precursor of furanone-based species from cellulose is evidenced thanks to the soft ionisation and MSMS structural analysis of ions. Different lignin markers and evolutions upon time of conversion are shown for miscanthus and oak pyrolysis.

Effect of fast pyrolysis conditions on biomass solid residues at high temperatures

“…Williams et al [33] suggested that biomass with a high content of lignin may form larger soot fractions due to its ability to generate phenolic tars. A significant fraction of aromatic tars and soot originates from lignin pyrolysis, mainly composed of guaiacol and syringol-type units [34][35][36]. Ross et al [37] stated that wood soot contains PAH material, promoted by the presence of acetylene at higher temperatures.…”

Detailed kinetic study of anisole pyrolysis and oxidation to understand tar formation during biomass combustion and gasification

“…The aim of this work is to deeply understand these reactions under conditions representative of biomass gasification in air-blown fluidized beds, but also PAH formation in wood combustion furnaces [9]. A significant fraction of aromatic tars and soot originates from lignin pyrolysis products mainly composed of guaiacol-type and syringol-type units [5], [10], [11] and [12]. Carbohydrates from cellulose and hemicellulose can also contribute to aromatic formation through the production of light unsaturated species such as acetylene and propargyl radicals [5], [13] and [14].…”

Lignocellulosic biomass as sustainable feedstock and materials for power generation and energy storage

“…3(b) [50,53,64]. More extensive sequential depolymerization reactions dominate in the temperature rangẽ 300-400°C, resulting primarily in the formation of levoglucosan (1, 6-anhydro-beta-d-glucopyranose), a dehydrated analogue of glucose, and other primary anhydrosugars and oligosaccharides [67]. Yields of up to around 60 wt% levoglucosan have been reported [59].…”