At present, the main method for preparing white carbon black is chemical vapor deposition (CAV), which is also called pyrolysis, dry or combustion. The raw materials are generally silicon tetrachloride, oxygen (or air) and hydrogen, which are formed by reaction at a high temperature. The reaction formula is: SiCl4+2H2+O2—>SiO2+4HCl. The air and hydrogen are respectively pressurized, separated, cooled and dehydrated, dried by silica gel, filtered by dust, and sent to a synthetic hydrolysis furnace; after silicon tetrachloride is rectified by a rectification column, it is heated and evaporated in an evaporator, and dried and filtered. The air is used as a carrier and is also sent to a synthetic hydrolysis furnace. After gasification of silicon tetrachloride at a high temperature, gas phase hydrolysis is carried out with a certain amount of hydrogen and oxygen (or air) at a high temperature of about 1800 ° C; the fumed silica particles formed at this time are extremely fine, forming gas with gas. The sol is not easy to trap, so it is first aggregated into larger particles in the concentrator, then collected by a cyclone, then sent to a deacidification furnace, and the fumed silica is purged with nitrogen-containing air to a pH of 4-6. It is the finished product.
Preparation and Application of Catalytic Materials in Huanggang Normal University
Researchers in key laboratories in Hubei Province use metals (iron ore tailings, copper mine tailings and other tailings) or non-metallic tailings (fly ash, quartz tailings, etc.) in the study of such materials. The low-temperature synthesis method has prepared the gas phase white carbon black. The preparation of the gas phase white carbon black prepared by the method is superior to the existing standard requirements of the fumed silica, and has high purity SiO2 ≥ 99.9%, specific surface area ≥ 350 Square meter / gram, pH = 7, metal impurity content is less than ≤ 50ppm. At present, Huanggang Teachers College has applied for more than ten national invention patents for this method. This method will rewrite the production history of fumed silica and has stronger competitiveness than the existing high temperature hydrolysis method.