Titanium tetrachloride is a colorless or slightly yellow liquid with a relative density of 1.726. It has a melting point of -25℃ and a boiling point of 136.4℃. It has a pungent acid odor, is easily hydrolyzed, and generates white smoke in moist air. It is soluble in water while decomposing, as well as in alcohols and concentrated hydrochloric acid, and is miscible with chloroform and carbon tetrachloride. It is produced by mixing titanium dioxide, carbon black, and molasses into blocks, and then carbonizing and chlorinating them by passing them through chlorine gas at temperatures above 600℃ or using chlorinating agents such as carbon tetrachloride. Titanium tetrachloride is a raw material for preparing metallic titanium and titanium compounds such as titanium dioxide and titanium trichloride. It is an important component of ethylene polymerization catalysts and is used as a smoke agent in the military and as a mordant in the dye industry. It is corrosive and should be handled with care during storage and transportation.
Nano titanium dioxide is a typical photocatalyst with advantages such as high catalytic activity, chemical stability, non-toxicity, and safety in use, and has broad prospects for application in wastewater treatment. However, in the actual use of nano titanium dioxide, there are disadvantages such as poor dispersion and difficult recovery, which limit its industrial application. In recent years, the use of various carriers to prepare supported titanium dioxide photocatalysts has received much attention, among which silicate minerals, as photocatalyst carriers, have been widely applied due to their abundant reserves, low price, large specific surface area, excellent adsorption properties, and ease of recovery.
(1) Firstly, the silicate mineral is added to a solution of titanium tetrachloride, and the hydrochloric acid generated by the hydrolysis of titanium tetrachloride solution is used to activate and dissolve impurity ions in the silicate mineral.
(2) Then, a certain alkaline solution is added to convert the titanium ions in the solution into titanium dioxide hydrate precipitates, wash away other impurity ions, and obtain a filter cake of titanium dioxide hydrate and silicate mineral composites.
(3) The filter cake is then added to a solution of titanium tetrachloride, and the acidic environment generated by the hydrolysis of titanium tetrachloride solution is used to dissolve titanium dioxide hydrate, reactivate silicate minerals, low-temperature crystallize and grow nano titanium dioxide on silicate minerals, filter, wash, dry, crush, and finally obtain titanium dioxide and silicate mineral nanocomposites.
Entering the 21st century, people are paying more and more attention to environmental protection. SOx produced by the combustion of sulfur-containing gasoline is one of the main air pollutants, especially SO2 in the atmosphere can cause various respiratory diseases, induce cardiovascular diseases, and SOx is the main cause of acid rain. Currently, countries around the world strictly control the sulfur content in fuel, so the production of low-sulfur gasoline or even sulfur-free gasoline is the hot spot of today's refining industry.
Gasoline desulfurization technology can be simply divided into hydrodesulfurization (HDS) and non-hydrodesulfurization. HDS must be carried out under high temperature and high pressure, which not only has huge equipment investment and operating costs, but also causes a large loss in the octane number of gasoline. Non-hydrodesulfurization technology includes adsorption desulfurization, biological desulfurization, oxidation desulfurization, and extraction desulfurization. Among them, adsorption desulfurization has the advantages of mild operating conditions, low investment and operating costs, simple process, and the ability to selectively adsorb organic sulfur compounds with less loss of octane value, and is praised as the most promising technology for producing sulfur-free gasoline in the future.