Silica aerogel (SA) is a nanoporous material and has attracted increasing attention in the field of thermal insulation in recent years. In this work, the thermal stability and pyrolysis characteristics of the methyltrimethoxysilane (MTMS) silica aerogel (MSA) prepared in pure water were investigated experimentally. The MSA shows a high thermal stability with the onset and peak temperature (T_onset and T_peak) about 417 °C and 476 °C, respectively, in the pyrolysis process. The oxidation kinetics reveals that the pyrolysis of MSA can be divided into three stages with the average apparent activation energy (E) of each stage being 382.8 kJ/mol, 364.4 kJ/mol, and 328.9 kJ/mol, respectively. The pre-exponential factor (A) has the same tendency with the E. The TG-FTIR analysis demonstrates that the CO₂ and H₂O are the main volatiles during the pyrolysis process and all of them increase against the temperature. It is further observed that the production of CO₂ presents a linear increase, and the H₂O shows an obvious two-stage form along with the temperature. Compared with other hydrophobic SAs, the MSA has a larger T_onset and T_peak and much larger E, indicating better thermal safety. The research outcomes provide a technical guide to analyze the thermal pyrolysis of hydrophobic SA and put a new insight to reduce their thermal hazards, which is beneficial to the development of higher-performance nanoporous silica aerogels for the thermal insulation field.

二氧化硅气凝胶（SA）是一种纳米多孔材料，近年来在隔热领域受到越来越多的关注。在这项工作中，对在纯水中制备的甲基三甲氧基硅烷（MTMS）二氧化硅气凝胶（MSA）的热稳定性和热解特性进行了实验研究。MSA显示出高的热稳定性，热解过程中的起始和峰值温度（T_起始和T_峰值）分别约为417°C和476°C。氧化动力学表明，MSA的热解可分为三个阶段，每个阶段的平均表观活化能（E）分别为382.8 kJ / mol，364.4 kJ / mol和328.9 kJ / mol。指数前因子（A）与E具有相同的趋势。TG-FTIR分析表明，CO ₂和H ₂ O是热解过程中的主要挥发物，并且它们都随着温度的升高而增加。进一步观察到，CO _2的产生呈线性增加，并且H ₂ O随着温度显示出明显的两阶段形式。与其他疏水性的SA相比，MSA具有较大的牛逼_发病和牛逼_的峰值和更大Ë，表明更好的热安全性。研究成果为分析疏水性SA的热解提供了技术指导，并为减少其热危害提供了新见识，这有利于开发用于隔热领域的高性能纳米多孔二氧化硅气凝胶。