香蕉假茎废弃量大，但由于其含水量高、富含碱金属及碱土金属、能量密度低等问题，限制了燃料化利用，而高压CO₂水热处理为非蒸发湿法转化处理工艺，可高效的脱水、脱碱，并提高热值。利用电子扫描显微镜(SEM)、气体吸附分析仪(BET)、X射线衍射仪(XRD)、傅里叶变换红外光谱(FTIR)、热重分析仪(TGA)等表征手段，考察了高压CO₂水热处理对香蕉假茎理化性质及燃烧特性的影响。研究表明，随水热温度升高，固体产率降低，其高位热值增加，且最大可增至25.76 MJ/kg。随水热温度升高，样品层间三维结构被破坏形成片状结构，随刻蚀程度的进一步加剧，进而形成新的三维网状结构。因此，样品比表面积呈现先增加，后减小，随后升高。而表观形貌复杂程度加剧，孔隙结构发达，使得样品的燃烧性能改善。与此同时，水热温度在120～200 ℃时，由于易燃的半纤维素与非晶纤维素解聚成小分子，直至完全消失，样品着火温度增加，综合燃烧特性指数增加。当水热温度在200～280 ℃时，纤维素Ⅰ开始分解并转化为热稳定性更高的纤维素II，进而样品着火温度降低，综合燃烧特性指数降低。此外，随着水热温度升高，木质素的含量增加，燃尽温度升高。利用Flynn-Wall-Ozawa(FWO)法燃烧动力学分析，除280 ℃水热样品，其余样品的平均活化能均高于原样。综合比较能量回收率及燃烧性能，经过240 ℃的高压CO₂水热处理后获得的水热焦其综合理化性能最优。

Because of its high moisture content, alkali metal and alkaline earth metal concentration, and low energy density, banana pseudo-stem with huge reserves is difficult to be utilized as fuel. The high pressure CO₂ hydrothermal treatment, a non-evaporative wet conversion process, has a greater drying efficiency, as well as a higher removal rate of alkali metals and alkaline earth metals. In addition, the heat value of samples after this treatment are increased. In this study, the SEM, BET, XRD, FTIR, and TG were used to investigate the evolution of physicochemical properties and combustion characteristics of banana pseudo-stem. The results revealed that the hydrochar yield decreases with increasing hydrothermal temperature. In addition, the higher heating value of samples increases from 13.02 to 25.76 MJ/kg with increasing hydrothermal temperature. With increasing hydrothermal temperature, the spatial structure of samples changes from irregular and highly distributed interconnected hierarchically to sheet structure, followed by new three-dimensional configuration porous microstructures. As a result, the specific surface area of the samples firstly increases, then decreases and finally increases with increasing hydrothermal temperature. This phenomenon may improve the combustion performance of the samples. Moreover, the ignition temperature and combustion character index of hydrochar increase at 120−200 ℃ due to the hydrolysis of the hemicellulose and amorphous cellulose. At 200−280 ℃, the ignition temperature and combustion character index of hydrochar decrease due to the transition from cellulose I to cellulose II. Furthermore, the burnout temperature increases with increasing hydrothermal temperature. According to the Flynn-Wall-Ozawa method, the average activation energy of samples are higher than raw samples, except for hydrochar at 280 ℃. Combining the energy recovery rate, ignition temperature, burnout temperature and combustion character index, the optimal temperature for banana pseudo-stem by the high pressure CO₂hydrothermal treatment is found to be 240 ℃.