Cost-effective pilot-scale demonstration of ambient-dried silica aerogel production by a novel one-pot process

Abstract

Over the past decade, aerogel based insulation products have established their place in various niche markets, such as thermal insulation for aerospace, apparel, petrochemical pipelines and pumping fluid media in industry applications. In the building industry, aerogel superinsulation enables superior insulation performance compared to conventional insulation materials. This allows putting in place a slimmer insulation layer (and thus space saving) or improving the insulation performance (U-value) of the building envelope. The widespread application of silica aerogels is currently hindered by their poor mechanical properties [1] and high materials cost. Aerogel insulation products have a tremendous growth potential in excess of 20 % by volume per annum [2]. For comparison conventional insulation products grow at an annual rate on the order of 5 %. One of the cost limiting key challenges in aerogel production is the cumbersome multistep synthesis methodology. Today’s aerogel production requires several solvent exchange steps which is not only very time and labor intensive but also costly. Supercritical drying from CO2 is another major obstacle in the mass production of silica aerogels due to the fact that it is done in high pressure autoclaves. Not only does this process require an additional solvent exchange step into CO2 but it is also accompanied by a significant energy cost. Two years ago, a novel one-pot production process for silica aerogels was invented and patented at our laboratory which allows the production of silica aerogel granulate by ambient pressure drying within only 5 hours from start to finish. This simplified chemical synthesis consists of only three steps: gelation, modification and ambient pressure drying. Currently we are able to produce up to 70 liters at a time, following a first successful scale-up study. Our in-house aerogel has a thermal conductivity of 17.9 mW/(m K), which is identical to that of commercially available granulate (e.g. Cabot P300). In summary, this new process gives access to a new generation of low-cost high-quality aerogel granulate and is expected to substitute today’s conventional processes. A significant price reduction of silica aerogel materials is expected to reshuffle the insulation market. In the future we should look forward to seeing new aerogel insulation products and companies appear on the world markets.