Influence of drying technique on Pt/In2O3 aerogels for methanol steam reforming

Abstract

In this paper we present a comparison of aerogels which are dried under different conditions. Of those, most important are the solvent, temperature, and pressure. Criteria of comparison rely mostly on results from analysis of nitrogen adsorption experiments, as well as transmission electron microscopy imaging. Platinum loaded indium oxide aerogels were picked as a model system for this study as they can be used as highly effective heterogeneous catalysts in methanol steam reforming. The compared drying methods include supercritical drying from CO2, supercritical CO2 - ethanol mixture, freeze drying from tert-butanol and ambient conditions drying from acetone and 1-Methoxyheptafluoropropane. High porosities and large specific surface areas can be achieved via supercritical, freeze- and ambient conditions drying, while retaining the original gel morphology in this system for most methods except freeze drying and ambient conditions drying from acetone.Schematic of a phase diagram (left) describing drying methods for solvogels by sublimation, evaporation or supercritical drying of the solvent. The results of those methods on the final aerogels are compared for the system of indium oxide aerogels loaded with platinum nanoparticles.