Robust SiO2 –Al2 O3 /Agarose Composite Aerogel Beads with Outstanding Thermal Insulation Based on Coal Gangue

Abstract

Advanced SiO2 –Al2 O3 aerogel materials have outstanding potential in the field of thermal insulation. Nevertheless, the creation of a mechanically robust and low-cost SiO2 –Al2 O3 aerogel material remains a considerable challenge. In this study, SiO2 –Al2 O3 aerogel based on coal gangue, which is a type of zero-cost inorganic waste, was constructed in porous agarose aerogel beads, followed by simple chemical vapor deposition of trimethylchlorosilane to fabricate SiO2 –Al2 O3/agarose composite aerogel beads (SCABs). The resulting SCABs exhibited a unique nanoscale interpenetrating network structure, which is lightweight and has high specific surface area (538.3 m2/g), hydrophobicity (approximately 128◦), and excellent thermal stability and thermal insulation performance. Moreover, the compressive strength of the SCABs was dramatically increased by approximately a factor of ten compared to that of native SiO2 –Al2 O3 aerogel beads. The prepared SCABs not only pave the way for the design of a novel aerogel material for use in thermal insulation without requiring expensive raw materials, but also provide an effective way to comprehensively use coal gangue.