Macauba ( <i>Acrocomia aculeata</i> ) as a Bioenergy Platform: Integrated Biodiesel Production and Lignocellulosic Biomass Valorization

Macauba (<i>Acrocomia aculeata</i>) is a native palm from tropical regions with high potential for integrated bioenergy and bioproduct applications. This study evaluated the physicochemical properties of macauba pulp and kernel oils, assessed the production and fuel properties of biodiesel derived from commercial pulp oil, and explored the use of macauba lignocellulosic biomass for biochar production. Pulp oil exhibited a high oleic acid content, which makes it highly suitable for biodiesel synthesis since oleic acid forms esters with good oxidative stability, adequate fluidity, and high combustion quality, resulting in a biodiesel that readily meets fuel standards. Biodiesel was obtained through a two-step process, and its blends with fossil diesel (DS10 and DS500: commercially available fossil diesel fuels containing up to 10 mg kg^-1 and 500 mg kg^-1 of sulfur, respectively) were evaluated in terms of density, kinematic viscosity, and heating value. The results indicate that up to 60% (v/v) methylmacauba biodiesel (MMB) can be blended with DS10 and up to 90% with DS500 without exceeding regulatory limits. Additionally, biodiesel production in a continuous tubular reactor confirmed its technical feasibility, yielding more than 70% under optimized conditions. Pyrolysis of macauba biomass at 400-600 °C generated biochar with increased carbon content, energy density, and structural ordering. Biochars derived from extractive-containing biomass exhibited distinct elemental and energetic profiles compared with extractive-free samples. These findings reinforce the suitability of macauba as a versatile and sustainable feedstock for biorefinery platforms.