Styrene upstream and downstream industry chain and production process detailed explanation, dry goods! Recommended collection!
What is styrene?
Styrene, also known as vinylbenzene, is an organic compound formed by replacing one of the hydrogen atoms of ethylene with benzene. At room temperature, styrene is a viscous and volatile liquid with a sweet taste, but when the concentration of styrene is too high, the smell will become unpleasant. In styrene, the electrons of the vinyl group are conjugated with the styrene ring. Styrene is insoluble in water, soluble in ethanol and ether, and gradually polymerizes and oxidizes when exposed to air. Industrially, it is an important monomer for synthetic resins, ion exchange resins, and synthetic rubber.
Styrene chemistry & storage method
Styrene double bonds are chemically active and can be slowly polymerized at room temperature. Styrene self-polymerizes to form polystyrene resins. It can also copolymerize with other unsaturated compounds to form various products such as synthetic rubber and resins.
Styrene autopolymerization affects product quality. Therefore, styrene storage should add polymerization inhibitors [hydroquinone or tert-butylcatechol (0.0002%~ 0.002%) as stabilizers to delay its polymerization before storage, and the storage temperature should be below 25 ° C. The maximum inventory time agreed between storage tank companies and customers is generally no more than 90 days, and transportation operations should avoid high temperature periods.
Where did styrene come from?
There are three main production processes for styrene, the main ways are ethylbenzene dehydrogenation, PO/SM co-production, and cracking gasoline extraction.
1. Ethylbenzene dehydrogenation
The dehydrogenation of ethylbenzene to styrene at 550~ 600 ℃ under the action of catalyst is the main method for the production of styrene at home and abroad, and its capacity accounts for about 90% of the world's total styrene capacity.
Features: The process technology is quite mature, the product purity is high, the device runs smoothly, and the operation elasticity is large.
2. PO/SM co-production method
This is the propylene oxide-styrene co-production process, also known as co-oxidation. Ethylbenzene is oxidized with oxygen to form an ethylbenzene peroxide, which is then used to oxidize propylene to give 1-phenyl ethanol and propylene oxide. Finally, 1-phenyl ethanol is dehydrated to give styrene.
Features: While producing styrene per ton, 0.4t of propylene oxide can be co-produced. It does not require the high temperature of the dehydrogenation method, and can avoid the pollution problem of the production of propylene oxide by the chlorine alcohol method. However, the reaction is complicated, there are many by-products, and the process is long, and the unit consumption of ethylbenzene is higher than that of the dehydrogenation method.
3. Extraction method of cracked gasoline
This is a new technical route for styrene production that has not been widely used in recent years. The cracked gasoline produced by the steam cracking ethylene production unit with naphtha, diesel oil, and liquefied petroleum gas as raw materials contains about 4% -6% styrene, which can be separated by extraction.
Features: Products are generally high in chromaticity, contain sulfur, and fluctuate widely (can be used in areas with lower requirements such as UPR).
Styrene upstream feedstock
Directly upstream of styrene are ethylene and pure benzene.
1. Pure benzene
Basic chemical raw materials. The application of pure benzene mainly includes styrene, caprolactam, aniline and phenolone, among which the largest downstream of pure benzene is styrene. In 2018, the consumption of styrene to pure benzene in our country accounted for 39%.
2, ethylene
There are many downstream derivatives of ethylene, of which styrene is the fourth largest ethylene derivative after polyethylene (PE), polyvinyl chloride (PVC) and ethylene oxide (EO).
Main downstream products of styrene and their end point applications
Kerosene is supported on styrene, and rubber and plastic are connected next. The main downstream products involve expanded polystyrene (EPS), polystyrene (PS), ABS resin, synthetic rubber (SBR, SBL, SBS, etc.), unsaturated polyester resin (UPR) and styrene copolymer (such as SBC). The end point is mainly used in plastics and synthetic rubber products.
1. Expandable polystyrene (EPS)
EPS is a product made of styrene, foaming agent and other additives. It has the advantages of low relative density, low thermal conductivity, low water absorption, shock and vibration resistance, heat insulation, sound insulation, moisture resistance, vibration reduction, and excellent dielectric properties.
2. Non-expandable polystyrene (PS)
Divided into general-purpose polystyrene (GPPS) and high-impact polystyrene (HIPS).
Generic Polystyrene (GPPS): A thermoplastic resin made from the polymerization of styrene monomer, which is a colorless, odorless, odorless, transparent, and glossy bead or granular solid. The advantages are high transparency, good rigidity, high fluidity, and good electrical insulation. The disadvantage is that it is prone to stress cracking (more brittle).
End point applications: GPPS is commonly used in electrical instrument housings, cosmetic containers, optical parts (e.g. prisms, lenses), toys, lamps, and other daily necessities such as tableware.
High impact polystyrene (HIPS): It is a thermoplastic material obtained by adding cis-polybutadiene rubber to styrene in order to solve the disadvantage of impact brittleness of GPPS. Generally, the addition ratio is about 8%. After adding cis-butadiene rubber, the toughness of polystyrene is greatly improved at the cost of loss of transparency.
end point application: HIPS is commonly used in electrical enclosures/parts, instrumentation accessories, stationery/toys, etc.
3. Acrylonitrile-butadiene-styrene (ABS)
ABS resin is one of the five major synthetic resins. It is a copolymer of acrylonitrile (A), butadiene (B) and styrene (S). It has the advantages of impact resistance, heat resistance, low temperature resistance, chemical resistance and excellent electrical properties. It can also be used for secondary processing such as surface spraying metal, electroplating, welding, hot pressing and bonding.
end point application: It is widely used in household appliances, automobiles, electronic appliances, instrumentation, textiles and construction and other industrial fields, of which household appliances account for about 60%. It is a widely used thermoplastic engineering plastic.
4. Unsaturated polyester resin (UPR)
A kind of chemical raw material, it is a linear polymer formed by polycondensation of saturated dibasic acids, unsaturated dibasic acids and dibasic alcohols, and a resin solution with a certain viscosity formed by dilution of crosslinking monomers or active solvents. UPR is easy to produce, easy to obtain raw materials, low viscosity of the product, many molding processes, and curing at room temperature and pressure.
end point application: UPR is the most used variety of thermosetting resins in our country, and it is also the most used matrix resin in domestic fiberglass, artificial stone, handicrafts, etc.
5. Styrene-butadiene rubber (SBR)
Also known as polystyrene butadiene copolymer. Its physical properties, processing properties and product performance are close to natural rubber, and some properties such as wear resistance, heat resistance, aging resistance and vulcanization speed are better than natural rubber. It can be used with natural rubber and various synthetic rubbers.
end point application: widely used in the manufacture of tires, tapes, rubber shoes and other rubber products, in recent years, widely used in diving materials, such as wetsuits, sports protective gear, body sculpting products, gifts, thermos cup covers, fishing pants, shoe materials and other fields.
Styrene capacity
Since 2006, the development of domestic styrene production capacity has gradually accelerated. By 2018, there were 44 styrene manufacturers and 52 production lines in China, with a total capacity of 9.25 million tons, accounting for 1/3 of the global total capacity. In the next few years, with the supporting downstream styrene plants of large domestic refining and chemical enterprises and the gradual commissioning of private refining and chemical integration projects, the domestic styrene industry has maintained a high-speed capacity expansion.
From a regional perspective, domestic styrene plants are mainly distributed in East China, North China, South China, and Northeast China. Among them, 43% of the production capacity is distributed in East China, 23% in North China, and 14% in South China. The new production capacity in the next three years will be mainly distributed in North China, East China, South China and other places.
High performance plastics applications
With the development of new energy vehicles, the rise of 5G communication and the implementation of the sharing economy, the performance requirements of materials such as strength, temperature resistance, weather resistance, and low dielectric properties have been improved, and the application demand for high-standard plastic materials has increased rapidly. Differentiated high-end modified plastics will usher in the spring of development.
At the "High Performance Plastics Application Technology Forum" in November this year, Aimans, Covestro, Ascend, Kaidefu, Jiaxing Domo, Kumho Rili, Fujitsu, SAIC Motor, and Jaguar Land Rover will bring you exciting sharing of "innovative materials" and "application materials".
