Nanosized ZSM 5 zeolite was synthesized by hydrothermal method and characterized by XRD and TEM techniques. The specific heat of the nanosized ZSM 5 zeolite was measured in the temperature range from 79 to 370 K, and its enhancement in specific heat was observed as compared with the corresponding microsized zeolite, indicating that the nanosized ZSM 5 zeolite possesses higher surface activity. The thermostability of the samples was determined by differential scanning calorimetric (DSC) and thermogravimetric (TG) techniques. The DSC results showed that, for the nanosized ZSM 5, a broad exothermic peak is observed from 1?300 K; for the microsized ZSM 5, the corresponding exothermic peak begins at 1?400 K, and a distinct phase transition can be observed at 1?620 K. The TG results showed that, for the nanozised ZSM 5, the maximum mass loss ratio is 6 9%, and two mass loss stages can be observed in the temperature ranges of 298～663 K and 923～ 1?273 K, respectively; for the microsized ZSM 5, the maximum mass loss ratio is 6 5% and it is more stable than the nanosized ZSM 5.
The heat capacities of KHSO4 crystal (A. R. ) have been measured with a small sample precision automated adiabatic calorimeter over the temperature range from 78 to 373 K. The experimental results have shown that there is no phase transition or thermal anomaly in this temperature region for the present crystal. The experimental heat-capacity data have been fitted to a smoothed curve with the aid of the least square method. In addition, the process of the thermal decomposition has been studied by TG analysis.
