The existence of sulfur in oil and natural gas has added a lot of trouble to the process of oil refining and natural gas processing. Sulfur can not only cause corrosion of equipment and pipelines, but also greatly reduce the quality of petroleum products. In the quality indicators of gasoline and diesel, the sulfur content is a very important indicator. The emission of sulfur-containing gases such as sulfur dioxide and hydrogen sulfide also causes air pollution, increases greenhouse gas emissions, and causes harm to the earth on which we all depend for survival. Therefore, all countries in the world attach great importance to the sulfur content in petroleum and petroleum products. In the process of petroleum processing, as far as possible, various forms of derivatives of sulfur are removed and hydrogen sulfide is made into sulfur for recycling. On the one hand, it is to improve the quality of petroleum products and reduce the corrosion of equipment, and at the same time, it is also an important measure to protect the environment and turn waste into treasure.
In the process of petroleum refining, sulfur recovered through product refining, desulfurization, sour water stripping and sulfur recovery is widely used in the development of the national economy. Sulfur has a variety of uses in various production fields. It is no longer a single trouble in petroleum processing, but a real precious resource.
Sulfur is an important chemical raw material, widely used in agriculture, medicine, catalyst, rubber, gunpowder, building materials, construction, food and other fields, most of which are used to produce sulfuric acid. According to information, more than 80% of the world’s sulfur is used to produce sulfuric acid, followed by the production of various special sulfur and special sulfur. According to statistics, in the first half of 2007, the production of sulfuric acid in my country accounted for 46% of the total output of sulfuric acid, equivalent to 3.87 million tons of sulfur. Since sulfuric acid is a low value-added product and the market competition is fierce, it is of great significance to the national economy to actively develop high value-added sulfur chemical products and expand the sulfur product chain.
1. Fine vulcanized chemical products
Fine sulfur chemical products have unique physical and chemical properties, and are widely used in the production of feed, pesticides, medicines, solvents, surfactants, oil additives, molecular weight regulators and other products.
Methionine
Methionine is a fine sulfur chemical product that has developed rapidly in recent years, and is widely used in medicine, food, feed and cosmetics industries, among which the feed industry has the largest demand. Methionine is an essential amino acid for animals and a nutrient for fortifying feed; it is one of the main components of amino acid infusion and compound amino acids. At present, the global production capacity has reached 0.5Mt/a, while China’s production capacity is still less than 0.01 Mt/a, and the import volume exceeds 0.02 Mt/a. With the rapid development of the feed industry, the annual growth rate of methionine demand in recent years will reach 7% to 8%.
Thiourea
Thiourea is a chemical product that is very scarce in domestic and foreign markets. It can be used in the manufacture of drugs, epoxy resins, fuels, rubber vulcanization accelerators, diazo sensitizers, thiourea peroxide, cold ironing agents and resin compression molding powder. It can be used as a catalyst for phthalic anhydride and fumaric acid.
Methyl mercaptan
Methyl mercaptan, also known as sulfhydryl methane and methane mercaptan, is a colorless gas with molecular formula CH3SH, boiling point 5.95°C, freezing point -123°C, density 0.8665 (d420), flash point -18°C, soluble in alcohol and ether. Methyl mercaptan belongs to the thiol organics with the smallest relative molecular mass, is very active, has high activity, and is easy to react with other substances to form sulfur-containing compounds. It is an important organic synthesis intermediate and is widely used in medicine, pesticides, In the production of fuel and feed, it is the main raw material for the synthesis of methionine, and it is an intermediate for the production of methomyl, fenthion, promethazine and other pesticides.
2. Insoluble sulfur
Insoluble sulfur, abbreviated as IS in English, is a linear polymer formed by ring-opening polymerization of ordinary sulfur above the critical temperature (159°C). 108 or more. Because its structure is similar to that of high molecular polymers, it is also called polymeric sulfur.
The commonly used insoluble sulfur product is yellow powder with a density of 1950kg/m3 and a relative molecular weight of 3200-40000. Due to the difference in molecular structure, it is insoluble in organic solvents that have strong dissolving ability to ordinary sulfur, such as carbon disulfide (CS2), etc., so it is called insoluble sulfur.
3. Sulfur fertilizer
Sulfur is the second most important crop nutrient element after nitrogen, phosphorus and potassium. In the 1980s, foreign countries have developed a variety of sulfur fertilizers directly applied in the form of elemental sulfur, such as sulfur-bentonite, sulfur urea, etc. Sulfur-bentonite is a kind of biodegradable fertilizer, which is a granule made by blending sulfur and bentonite, in which the content of sulfur is as high as 90%, which can prevent fruit mildew and crop diseases and insect pests; sulfur urea is wrapped on spherical urea with a layer Sulfur shell, this shell slows down the release rate of urea nutrients, prevents the loss of urea and improves its utilization rate. The effective utilization rate of nitrogen in sulfur urea is nearly double that of ordinary urea, and sulfur itself is a nutrient element, so it is widely used. Pay attention to.
4. Pesticides
Sulfur-based pesticides using sulfur as raw materials are still one of the most widely used inorganic pesticides at home and abroad because of their low price, wide sterilization and insecticidal range, and basically harmless to humans and animals. Such pesticides include lime sulfur mixture, wettable sulfur powder, sulfur colloidal suspension, etc. Among them, sulfur colloidal suspension is one of the new varieties of sulfur-based pesticides with the fastest development and ideal application effect, and has great development potential.
5. Building materials
Sulfur-containing building materials include sulfur concrete (including prefabricated parts, pressed parts and cast-in-place) and sulfur asphalt.
Sulphur concrete
At present, sulfur concrete is mainly made by the sulfur polymer method. First, a modifier is added to sulfur to make a sulfur polymer, which is called sulfur polymer cement. Then, at 127-149 °C, all the traditional sulfur polymer cement is replaced by sulfur polymer cement. Cement, mixed with concrete materials to make sulphur concrete. After screening and testing, it was determined that dicyclopentadiene (DCPD) and cyclopentadiene (CPD) oligomeric compounds were the most suitable modifiers.
Sulfur concrete is suitable for use in chemical, oil refining, fertilizer, papermaking and other enterprises with acids, alkalis, salts, solvents and chemicals; sewage treatment plants and sewage pipelines; waste utilization and burial utilities such as radioactive waste treatment facilities; karst collapse and Watering of underground gas storage; components of oil and gas field buildings in frozen areas; offshore drilling platforms; railway sleepers and other places. Sulfur concrete is not suitable for use at high temperatures because sulfur concrete cannot withstand long-term open fire combustion; operation at temperatures above the melting point of sulfur polymers for a long time will damage the structure of sulfur concrete.
sulphur pitch
Gulf Canada, French SNPA and other companies have researched and developed the SEA method to produce sulfur asphalt. The key to the technology is to first prepare a sulfur-asphalt adhesive, that is, to replace part of the asphalt with sulfur, and then mix it with other materials for road paving. A small amount of dispersant is added in the adhesive preparation process to promote the uniform mixing of sulfur and asphalt. After testing, the sulfur content in the adhesive must be at least 30%, and when it reaches 50%, the stability is more than double that of using pure asphalt, and the fluidity is also reduced. The sulfur content used in the actual construction is 35%. In addition to high stability and low fluidity, the sulfur asphalt produced by the SEA method also has the following advantages: long road service life; improved wear resistance; solvent corrosion resistance; lower viscosity than asphalt, easy to operate.
6. Na-S battery
The Na-S battery was developed with the increasingly stringent environmental regulations on the exhaust emission of fuel oil vehicles. It is characterized by high energy density, small size, low price, flexible design, and is not affected by ambient temperature. It consumes electrical energy, but its internal working temperature must be maintained above 300 ° C, so the insulation performance is required to be high. It is mainly used in electric vehicles. Developed countries such as the United States, Japan and Germany have achieved good results in this field. There are no reports on the development of Na-S batteries in my country. In order to reduce vehicle exhaust emissions, the technical development of Na-S batteries should be actively developed.