Impact of the Water Removal Method on Tetraethyl Orthosilicate Direct Synthesis: Experiment and Process Assessment

A direct synthesis pathway of tetraethyl orthosilicate from silica and ethanol was recently proposed. Although this pathway has many advantages over the conventional one producing tetraethoxysilane (TEOS) from metallurgical silicon, its potential can be further increased by the effective removal of its byproducts. This study investigates the removal of the water byproduct, which reduces the TEOS product yield and enhances the loss of raw materials. Several inorganic dehydrating agents were examined under different conditions, on the basis of which a suitable TEOS synthesis process using the selected dehydrating agent was designed and its optimal conditions were determined. The feasibility of the designed process was evaluated in comparison with our previously reported process using a molecular sieve as a water adsorbent and the conventional process. The evaluation results confirmed that the CaO process is more economically competitive and environmentally friendlier, reducing 24% production cost and 40% greenhouse gas emissions of the conventional process.