关键词: ATO, 超临界CO₂, 醇凝胶, 工艺优化, 动力学, 模型

Abstract:

Antimony doped tin oxide (ATO) has excellent optoelectronic properties. To obtain a small particle size and well-dispersed nano ATO materials in the drying process is a critical step in the preparation. In this paper, the supercritical drying time, temperature, pressure and CO₂ flow rate were studied as the main parameters affecting the nano ATO particle's size and specific surface area. In addition, the kinetic equations of drying curve were fitted. ATO nano particles with average particle size of 20-30 nm and high specific surface area of 75-80 m²·g^-1 were obtained with the supercritical CO₂drying process parameters: temperature (35-40℃), pressure (10-14 MPa), CO₂ flow rate (1.2-1.8 L·h^-1), drying time (5-6 h); and alcohol gel drying process could be divided into three stages: rising speed, uniform speed and decreasing speed. There was a critical point in the alcohol ratio (M_R) of alcoho gel, and when M_R was smaller than 0.4, drying slowed down from uniform speed to decreasing speed. However, large supercritical flow rate could not obviously increase drying rate on the other hand. In addition, the Weibull function was used to describe the kinetics of supercritical CO₂ drying process of alcohol gel. As a result, the kinetic model was built and the drying process could accurately be described by the Weibull function. The results could provide helpful reference for industrial production and control of wet gel dried by supercritical CO₂ in the preparation of well-dispersed nano particles.

Key words: ATO, supercritical carbon dioxide, alcohol gel, process optimization, kinetics, model