This review aims to compile and discuss the pre-processing procedures utilized previously to biomass thermal conversion techniques, in order to promote the sustainable production of biofuels and other commodities from biomass. These will ultimately replace fossil-based alternatives under an environment-friendly framework, and contribute to the attainment of circular economy goals. Pre-processing methods account for a significantly improved efficiency, as a more homogeneous, dry, suitable and consistent feedstock is achieved, supporting cleaner and proficient conversion methods. This may prevent the complete depletion of non-renewable resources, alleviating the effects of their overexploitation. Findings concerning the main constrains when using biomass as a feedstock for thermal conversion reveal that size, format, moisture content and heterogeneity are the main encountered issues. Whilst mechanical processes, drying, torrefaction and pelletisation have shown enhanced results for physical aspects as well as moisture; hydrolysis, hydrothermal and microwave-based techniques are seen as the most utilized to solve problems related to morphology, degradability and digestibility. It was also found that the most significant thermal conversion techniques are torrefaction, hydrothermal processing, gasification, combustion, pyrolysis and plasma gasification. Relative to the major types of biomass applied for the production of biofuels, these are wood and woody biomass, followed by herbaceous and agricultural streams.

本综述旨在汇编和讨论以前用于生物质热转化技术的预处理程序，以促进生物质燃料和其他商品的可持续生产。这些最终将在环境友好的框架下取代基于化石的替代品，并有助于实现循环经济目标。预处理方法显着提高了效率，因为获得了更均匀、干燥、合适和一致的原料，支持更清洁和熟练的转化方法。这可以防止不可再生资源的完全枯竭，减轻其过度开发的影响。关于使用生物质作为热转化原料时的主要限制因素的调查结果表明，尺寸、格式、水分含量和异质性是主要遇到的问题。虽然机械工艺、干燥、烘焙和造粒在物理方面和水分方面都显示出增强的结果；水解、水热和基于微波的技术被视为最常用于解决与形态、降解性和消化率相关的问题。还发现最重要的热转化技术是烘焙、水热处理、气化、燃烧、热解和等离子气化。相对于用于生产生物燃料的主要生物质类型，这些是木材和木质生物质，其次是草本和农业流。烘焙和造粒已在物理方面和水分方面显示出增强的结果；水解、水热和基于微波的技术被视为最常用于解决与形态、降解性和消化率相关的问题。还发现最重要的热转化技术是烘焙、水热处理、气化、燃烧、热解和等离子气化。相对于用于生产生物燃料的主要生物质类型，这些是木材和木质生物质，其次是草本和农业流。烘焙和造粒已在物理方面和水分方面显示出增强的结果；水解、水热和基于微波的技术被视为最常用于解决与形态、降解性和消化率相关的问题。还发现最重要的热转化技术是烘焙、水热处理、气化、燃烧、热解和等离子气化。相对于用于生产生物燃料的主要生物质类型，这些是木材和木质生物质，其次是草本和农业流。还发现最重要的热转化技术是烘焙、水热处理、气化、燃烧、热解和等离子气化。相对于用于生产生物燃料的主要生物质类型，这些是木材和木质生物质，其次是草本和农业流。还发现最重要的热转化技术是烘焙、水热处理、气化、燃烧、热解和等离子气化。相对于用于生产生物燃料的主要生物质类型，这些是木材和木质生物质，其次是草本和农业流。