CO₂ is the primary greenhouse gas emitted through human activities. CO₂ emissions from burning fossil fuels increased by approximately 2.7 percent in 2018, after global emissions of 35.8 Gt in 2017. Thus, finding energy and cost-effective methods to use the CO₂ generated from industries for productive purposes is crucial, abating CO₂ emissions while producing economic benefits. This paper aims to comprehensively review the effects of CO₂ on syngas, biochar and bio-oil from gasification and pyrolysis processes. It was found that the utilization of CO₂ during gasification and pyrolysis provides both control over syngas H₂/CO ratio and biochar with enhanced properties for high value applications. Furthermore, it was determined that co-gasification under CO₂ atmosphere can enhance synergistic effects. Results also showed that the presence of CO₂ can increase the hydrocarbon concentration of bio-oil due to the different reactions that can occur between biomass and CO₂ compared to biomass and N₂. The use of CO₂ as a feedstock also reduces the net CO₂ emissions and therefore provides environmental benefits. However, the utilization of CO₂ during biomass gasification and pyrolysis currently has some limitations, including the endothermic nature of gasification reactions, resulting in large energy and compressed CO₂ inputs, which can be expensive. It is recommended that comprehensive studies to address the current limitations of the utilization of CO₂ in biomass gasification and pyrolysis processes be conducted. Promoting the use of CO₂ is integral to global CO₂ emission reduction, aiding in efforts to achieve CO₂ emission regulations outlined by the Paris Agreement (PA).

CO ₂是人类活动所排放的主要温室气体。在2017年全球排放35.8 Gt之后，燃烧化石燃料产生的CO ₂排放量在2018年增加了约2.7％。因此，寻找能源和具有成本效益的方法来利用工业产生的CO ₂进行生产是至关重要的，这要减少CO ₂排放，同时产生经济效益。本文旨在全面回顾CO ₂对气化和热解过程中合成气，生物炭和生物油的影响。发现在气化和热解过程中利用CO ₂可以同时控制合成气H _2。/ CO比和生物炭具有增强的特性，可用于高价值应用。此外，已经确定在CO ₂气氛下的共气化可以增强协同作用。结果还表明，CO ₂的存在可以增加生物油的碳氢化合物浓度，这是由于与生物质和N ₂相比，生物质和CO ₂之间可能发生不同的反应。使用CO ₂作为原料还减少了CO ₂净排放量，因此提供了环境效益。但是，CO ₂的利用在生物质气化和热解过程中，目前存在一些局限性，包括气化反应的吸热性质，导致大量能量和压缩的CO ₂输入，这可能是昂贵的。建议进行综合研究以解决目前在生物质气化和热解过程中利用CO _2的局限性。促进CO ₂的使用是全球减少CO ₂排放不可或缺的一部分，有助于实现《巴黎协定》（PA）概述的CO ₂排放法规。