METHOD OF PREPARING SILICON TETRAFLUORIDE BY USING CRYSTALLINE SILICA

摘要

The present invention relates to a method of preparing silicon tetrafluoride (STF, SiF4) by using crystalline silica (SiO2). More specifically, the present invention relates to a method of preparing silicon tetrafluoride by reacting finely divided crystalline silica and hydrogen fluoride (HF) in the presence of concentrated sulfuric acid in a continuous manner. According to the present invention, silicon tetrafluoride can be economically prepared with high yield from crystalline silica which exists abundantly in the natural world, and the process productivity, workability and controllability can be improved remarkably. In addition, the problem of corrosion in the recycling process by concentrating diluted sulfuric acid can be solved through controlling the ratio between reactants such that no incorporated hydrogen fluoride remains after the reaction, or on the other hand the difficulty in filtering the product by finely divided particles can be avoided through controlling the ratio between reactants such that the crystalline silica reactant is consumed completely. Furthermore, since the used sulfuric acid can be isolated and recycled, the generation of discarded sulfuric acid can be minimized.