Hidrocarbonetos renováveis por meio da pirólise catalítica da madeira do Nim utilizando uma zeólita HZSM-5 de baixo custo

Abstract

The trees of the Azadirachta indica species, commonly known as 'neem,' are frequently found in Brazilian urban parks and gardens. The green waste resulting from urban pruning in these areas represents a low-cost and abundantly available lignocellulosic resource. In this context, neem wood emerges as an untapped biomass with the potential to be an accessible and readily available lignocellulosic resource for possible applications in the production of biofuels and value-added chemicals. This study is pioneering, being the first to explore the potential of recovering valuable renewable hydrocarbons from neem wood through catalytic flash pyrolysis.To achieve this goal, neem wood was subjected to flash pyrolysis in the presence of a low-cost HZSM-5 zeolite (and without a catalyst for comparative analysis), using an analytical micropyrolyzer coupled with gas chromatographic separation and mass spectrometry detection to assess the composition of condensable volatile products. Aiming to reduce the costs of catalytic flash pyrolysis, an HZSM-5 zeolite was synthesized by the hydrothermal method, employing low-cost precursor materials such as rice husk ash and diatomite as alternative sources of silica and aluminum. Due to the large quantity of neem wood produced, with a high carbon percentage, high higher heating value (HHV), a considerable percentage of volatile matter, and a low ash percentage, the merit of this lignocellulosic residue as a raw material for pyrolysis is justified. The predominant category in the condensable volatile products resulting from the flash pyrolysis of neem wood was composed of oxygenated compounds (74.8%), with a focus on phenolic compounds, valuable as platform chemicals. The condensable volatile products from neem wood were improved, resulting in a composition predominantly composed of hydrocarbons while substantially removing oxygenated compounds through the use of a low-cost HZSM-5 zeolite.Catalytic experiments also highlight the potential conversion of neem wood into a bio-oil enriched in monocyclic aromatic hydrocarbons, with toluene comprising more than a third of its composition. Another relevant discovery was that 100% of the hydrocarbon fraction fell within the gasoline carbon atom range (C5–C12), while 62% were in the aviation kerosene carbon atom range (C8–C16). This study demonstrated that catalytic flash pyrolysis, employing a low-cost HZSM-5 zeolite, represents a promising route for the selective recovery of renewable hydrocarbons from neem wood. This approach stands out as a sustainable precursor for advanced liquid biofuels (drop-in biofuels) in the perspective of a green economy.