Pellistor embedded with aerogel-like silica

For pellistor methane sensors, the amount of heat generated by methane combustion reaction is lost to ambient atmosphere through its semi-closed packaging at high working temperature. In order to minimise such heat loss, a new approach is proposed by introducing aerogel-like silica as a packaging material for thermal insulation. The block aerogel-like silica package is prepared by hydrophobic silica aerogel and tetraethoxysilane (TEOS) at ambient drying pressure. The experimental results show that the integrity and properties of aerogel-like silica are associated with the amount of TEOS and the drying conditions. The most successful sample was obtained with 10 wt% TEOS at 20°C.The specific surface area and the average pore size of the best sample are 412 m²/g and 14 nm, respectively. With the porous structure and thermal insulation of aerogel-like silica, the performance of the pellistor embedded in aerogel-like silica has been improved due to more combustion heat being reserved around the sensor. When the sensitivity reaches up to 40 mW%CH₄, the power consumption is about 106 mW for the pellistor with the aerogel-like silica package, while the power dissipation of the pellistor with the traditional package amounts to 120 mW.