(429c) Catalytic Pyrolysis of Lignocellulosic Biomasses: A Sugar Cane Bagasse and Salicornia Study

This contribution presents the results of the study of the catalytic pyrolysis from two sources of biomass, namely: sugar cane bagasse and salicornia. The main purpose of the study is to obtain more valuable (bio)products rather than the conventional products such as biofuels (bioethanol or biobutanol) or biogas.

In this sense, slow catalytic pyrolysis experiments were carried out on lignocellulosic biomass using sugarcane bagasse (SCB) of Mexican origin (Saccharum officinarum L.) and salicornia (Salicornia bigelovii) as feedstock, using H-ZSM-5 zeolite as catalyst. The objectives of this experimentation were to determine the optimal conditions for slow catalytic pyrolysis. The experiments were carried out in a laboratory scale batch reactor, in temperature ranges of 400 °C, 450 °C, 500 °C, 550 °C and 600 °C, with different biomass to catalyst ratios (1:1, 1:2 and 1:3), particle sizes of 850 μm – 297μm and 0.0070 μm – 0. 0029 μm for sugar cane bagasse and salicornia, respectively, with a heating rate of 10°C/min and, a residence time of 30 minutes once the reaction temperature was reached, feeding a flow of 85 mL/h of Nitrogen (N₂) to guarantee an inert atmosphere. Three products were obtained, a solid phase (charcoal), a liquid phase (pyrolysis liquid), and a gaseous phase (non-condensable pyrolysis components), for each of these products were used quantitative and qualitative analysis techniques of the organic compounds present in them, Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the components present both in the solid and liquid phases, gas chromatography for the liquid and gas phases, and HPLC-mass for the liquid phase only. The highest yield is obtained at temperatures of 500 and 550°C, and a 1:3 ratio, it was observed that the production of aromatics at these conditions was very favorable. Regarding the product of the solid phase SCB is the one that generates less charcoal, at the temperature of 500°C, and biomass to catalyst ratio (1:2), was at the conditions that a lower percentage was obtained (6.7%), in other words, about 90% of the raw material was transformed into gas and pyrolysis liquids. On the other hand, the salicornia has a higher production of non-condensables. During the experiments, the accumulation of gases was observed once the reaction reached 300°C; this is attributed to the halophytic properties of the plant (salinity). Based on the data obtained from chromatography and FTIR, the presence of oxygenated compounds is observed, mainly alcohols, aromatic groups, aldehydes, and furfurans, the presence of the phenol family and some alkanes is also evident in the liquid fraction.

Preliminary results have shown an increase obtention of aromatic compounds, mainly fenols, due to the use of a catalyst unlike the thermal pyrolysis where a large amount of components were detected without a clear distinction of a particular product. Nevertheless, both techniques with and without catalyst show promising results in terms of the possibility to use these resources as feedstocks for biorefineries.