The Exploration Of Displacement-dissolution Method For Silica Aerogels

In recent years, with the energy shortage and environmental problem, more and more teams try to research and explore new aerogel, hope to achieve the real industrialization of silica aerogel. As a basic target of simplifying the process, reducing the cost and protecting the environment, this paper has found a new method of syngas gel-displacement stripping. Using industrial sodium silicate as raw materials, the paper explores the application of different groups in polymer PEG molecular weight (600,1000,6000,10000), PVA and PAM displacement dissolution silica aerogel synthesis method. At the same time, try to introduce sodium alginate displacement dissolution silica aerogel synthesis. The specific research content is as follows.The paper already has synthetic organic-inorganic compound silica wet gel by adding polymer to silica hydrosol and using the method of sol-gel synthesis, furthermore, explored the replacement method of stripping and replacement after stripping out the influence of synthetic silica aerogel. Experimental results have showed that synthesis method of solid replacement after dissolution average aperture around 12 nm forms the three-dimensional network structure, displacement first stripping synthesis solid closer to dry gel, less porosity, huge particle. Compared the microwave rapid drying and baking oven, slow drying effect on the properties of composite solid and concluded that microwave drying is not applicable to the displacement solution synthesis silica wet gel.The basis of experimental groups are added into the different proportion of polymer, the proportion respectively 1%,5‰, 1‰,0.8‰,0.8‰,0.1‰,0.05‰. By comparison group testing, the experiments have got the sample performance of FI-IR, SEM, TEM, XRD, TG and DSC. The experimental results show that synthetic silica aerogel get low density and uniform structure when the introduction of polymer volume are 0.05‰ and 0.1‰. The results of the introduction of PEG substitution stripping experiments show that with the increase of PEG molecular weight, solid average pore diameter and pore volume decreases, and the specific surface area increased; silica aerogel particles or clusters which are synthesized by the method of PAM, PEG, PVA replacement dissolution are 10～20 nm in average diameter, 18 nm in average pore diameter, mostly, in the range of 1～25 nm of uniform distribution of holes, a small aperture at around 100 nm; silica aerogel which are synthetized by sodium alginate with replacement stripping form the three-dimensional network structure, and biological polymer monomer particle size is too huge, does not apply as replacement method of dissolution medium。The conditions of optimized processes which are optimization by using TMCS surface modification of synthetic silica aerogel are 45 ℃ constant temperature water bathing, sealing magnetic stirring. Optimal replacement stripping synthesis process (temperature, PH, time) concludes that replacement dissolution temperature from 80 ℃ heats up value 105 ℃,and cycle times; PH 6.2-6.4 gel reaction rate is in the fastest; replacement dissolution time reaches 72 hours. Contrast displacement stripping and TMCS surface modification method of silica aerogel performance, experimental results show that the average pore diameter of silica aerogels maded by displacement-dissolution method is greater than samples maded by TMCS surface modification method, at the same time its surface modification and the specific surface area and volume of particle clusters are much smaller than the latter.The paper does a feasibility study on the silica aerogels industrialization, analyzed the interior driving force of silica aerogels and industrialization operating mechanism. We also do the analysis of the macroeconomic environment on silica aerogels, using PEST. SWOT analysis is carried out on the aerogel production enterprises, according to the theory of material process engineering. Respectively from the technical innovation, personnel system, financing mechanism, and political and legal security system put forward measures to promote the industrialization of our country silica aerogel method. Proved that based on displacement dissolution method, the feasibility of silica aerogel with industrialization.