生物质作为一种可再生能源，具有来源广、多功能、碳中和等特点。生物质的高值资源化利用有利于降低对高碳化石能源的依赖程度，保障国家能源安全，减少环境污染，符合中国“双碳”国家战略需要。热解作为生物质热化学转化的基础，是实现生物质能高值利用的最佳技术之一，但是存在生物油产率低与品质差的核心问题。针对以上问题，创新性将低温冷冻技术应用于生物质热解领域，提出“低温冷冻+快速热解”的生物质制油新方法，拟提高热解生物油产率和品质。以2种农作物秸秆为实验研究对象，采用液氮快速冷冻预处理方法，研究了低温预处理下生物质热解产物分布与组成的演变机理。实验表明，与常规热解相比，液氮低温预处理后生物质热解生物油产率升幅可达14.16%～23.73%，且低温预处理温度与生物油产率呈正相关关系，在−90 ℃低温预处理下生物油产率达最大值(22.3%～26.3%)，超出铝甑法生物油产率8.5%～22.71%。液氮低温预处理对生物油成分分布有明显的转化作用，生物油组成中苯系物(BTEX)与酚类物质有明显上升，最大涨幅分别为43.61%和12.45%。液氮低温预处理抑制了生物质热解气中CO₂和CO的释放，成分占比降幅了7.2%～29.7%；促进CH₄和H₂的生成，成分占比提高了0.2%～14.7%。此外，低温预处理使固体产物元素组成中C元素含量增加，同时O元素含量下降，这有利于提高生物炭的可燃性，并降低其自燃风险。

Biomass, as a renewable energy source, features wide availability, multiple functions, and carbon neutralization. The high-value resource utilization of biomass is conducive to reducing reliance on high-carbon fossil energy, ensuring national energy security, and curbing environmental pollution, aligning with the needs of China's "dual carbon" national strategy. Pyrolysis, as the foundation of biomass thermochemical conversion, is one of the best technologies to achieve a high-value utilization of biomass energy. However, it has some core issues such as low bio-oil yield and poor quality. To overcome these problems, a cryogenic technology was innovatively applied to the field of biomass pyrolysis, and a new biomass oil production method of "cryogenic + fast pyrolysis" was proposed to increase the yield and quality of pyrolytic bio-oil. Taking two types of crop straw as experimental research objects, the rapid freezing pretreatment method with liquid nitrogen was adopted to study the evolution mechanism of the product distribution and composition of biomass pyrolysis under cryogenic pretreatment. The experiments show that compared with conventional pyrolysis, the increase in the bio-oil yield after cryogenic pretreatment of biomass pyrolysis can reach 14.16% to 23.73%, and the cryogenic pretreatment temperature has a positive correlation with the bio-oil yield, and the maximum bio-oil yield (22.3% to 26.3%) is reached at −90 ℃, exceeding the bio-oil yield of the aluminum method by 8.5% to 22.71%. The cryogenic pretreatment has a significant transformation effect on the composition of the bio-oil, and the content of benzene series (BTEX) and phenolic substances in the bio-oil composition increases significantly, with the maximum increase of 43.61% and 12.45%, respectively. The cryogenic pretreatment of liquid nitrogen inhibited the release of CO₂ and CO in biomass pyrolysis gas, and the proportion of components decreased by 7.2%～29.7%. In addition, the inhibition of the release of CO₂ and CO in the biomass pyrolysis gas and the increase of CH₄ and H₂ by cryogenic pretreatment increase by 0.2% to 14.7%. Moreover, the increase in C content and the decrease in O content in the solid product under cryogenic pretreatment are conducive to improving the combustibility of biochar and reducing its risk of spontaneous combustion.