Date Palm Biomass as a Feedstock for Renewable Fuels: Catalytic Pathways to Methanol, Ethanol, and Advanced Biofuels

The present paper highlights a critical assessment of the large-scale production and accumulation of date palm (Phoenix dactylifera) by-products. These have been identified as both serious environmental problems and potential renewable energy sources. Landfilling, burning in fields, and other such poor methods are common among many of the countries producing dates as ways to dispose of huge amounts of date palm by-products. The current literature has been assessed for their utilization in energy generation in the form of a circular bioeconomy with respect to the characteristics and composition of date palm seeds, leaflets, rachis and fibers. The study reveals that thermochemical conversion methods such as pyrolysis, gasification and hydrothermal processes are very efficient for the conversion of date palm residues into bio-oil, syngas and biochar. The resulting bio-oils are, however, rich in oxygen, acidic and unstable in nature and need to be upgraded using a catalytic process. Moreover, the review highlights that advanced catalytic technologies can greatly improve the quality of fuel through deoxygenation and the synthesis of hydrocarbons, resulting in the production of “drop-in” gasoline components and SAFs that have characteristics close to those of regular petroleum-based fuels. Also, artificial intelligence- and machine learning-based modeling techniques appear to offer considerable prospects in the realm of thermokinetic studies, process design, and large-scale implementation. Furthermore, the results point out two environmental advantages that accrue from the date palm valorization process, since biochar generated via thermochemical transformation can be used for seawater desalination. Lastly, the techno-economic evaluation and roadmap of future development directions are provided.