【Ten Years of Great Progress in Chemical Technology】047-2023: Zhejiang Petrochemical’s 1,000-ton α-olefin plant approved for safety review!

Zhejiang Petrochemical to Build 350,000 Tons/Year α-Olefin Plant On August 17, 2022, Rongsheng Petrochemical issued a announcement regarding an investment in high-end new material projects. To be built by Zhejiang Petrochemical, this project is expected to require an investment of 64.1 billion yuan; it aims to improve the efficiency of the facilities within the 40 million tons/year integrated refining and chemical processing complex. The plan includes constructing a new 4 million tons/year catalytic cracking plant, a 350,000 tons/year α-olefin plant, 2×200,000 tons/year POE polyolefin elastomer plants, an 80,000 tons/year polybutylene-1 plant, a 1 million tons/year acetic acid plant, 2×300,000 tons/year vinyl acetate plants, a 300,000 tons/year EVA/LDPE (tubular) plant, 2×150,000 tons/year adipic acid plants, a 250,000 tons/year adiponitrile plant, a 280,000 tons/year hexamethylenediamine plant, a 500,000 tons/year nylon 66 salt plant, a 600,000 tons/year maleic anhydride plant, a 500,000 tons/year 1,4-butanediol plant, a 200,000 tons/year PBS plant, a 120,000 tons/year poly**furan plant, a 30,000 tons/year NMP plant, a 270,000 tons/year nitric acid plant, a 660,000 tons/year acrylonitrile plant, a 200,000 tons/year SAR plant, a 300,000 standard cubic meters/hour CO2 reforming plant, a 1 million tons/year methanol plant, a 600,000 tons/year synthetic ammonia plant, a 240,000 tons/year bisphenol A plant, as well as various related utility facilities.

α‑Olefins As copolymerizing monomers for polyolefins, α‑olefins are mostly C4-C8 olefins; the copolymerization of 1-butene, 1-hexene, 1-octene with ethylene can yield high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and polyolefin elastomers (POE). They are also used as raw materials for the synthesis of high-grade lubricants, as well as for producing plasticizer alcohols and detergent alcohols. It can also be copolymerized with ethylene and propylene to produce propylene/ethylene/butylene terpolymer random polypropylene, or copolymerized with propylene to produce butylene-copolymerized polypropylene, etc. At present, China has a strong supply capacity for 1-butene; the production capacity for 1-hexene is insufficient although there are many planned projects, and progress is being made in the technology related to 1-octene. In 2022, the domestic production capacity of 1-butene was around 1.08 million tons per year, and it is expected to exceed 2 million tons per year by 2027. The main production methods are the C4 fractions produced as a by-product of ethylene plants and refinery catalytic cracking units, as well as the ethylene dimerization process. After the successful development of MTBE production technologies using isobutylene, the main method for producing 1-butene is the C4 separation process; the ethylene dimerization process has gradually been phased out from the market in recent years due to its high costs. The main production methods for 1-hexene include paraffin cracking, ethylene oligomerization, ethylene trimerization, and the Fischer-Tropsch process. The products of the ethylene oligomerization method are complex and difficult to separate; the main technology holders at present include Chevron Phillips, BP Amoco, INEOS, etc. The successful development of the ethylene trimerization to hexene-1 process technology by Sinopec and CNPC has broken the foreign monopoly. Currently, the ethylene trimerization method in China achieves high purity and yield, but its production capacity remains low. According to Yaha Consulting’s data, there are currently around 10 experimental and industrial projects for 1-hexene under construction or in the planning stage in China. 1-Octene is mainly produced through ethylene oligomerization, ethylene tetramerization, and the Fischer-Tropsch process. Among them, the ethylene tetramerization method attracts the most attention due to its advantages such as high product selectivity, high purity, and good atom economy. Only Sasol has achieved industrial production of the Fischer-Tropsch process; in China, Ningxia Coal Company has completed a pilot-scale separation project for producing alpha-olefins from Fischer-Tropsch oils, capable of manufacturing C6 and C8 alkenes. To date, domestic companies such as Maoming Petrochemical, Daqing Petrochemical, and Satellite Chemical have already built industrial pilot plants for 1-octene synthesis with a capacity of thousands of tons; moreover, several other pilot plants and industrial projects are currently under construction or in the planning stage. After 2025, the domestic market will enter a phase of capacity expansion. Traditional domestic α-olefin producers include Yanshan Petrochemical, Daqing Petrochemical, and Dushanzi Petrochemical; as of 2021, the total capacity for α-olefins with a carbon chain length of 6 or more was 75,000 tons. After 2022, barriers in the design phase of α-olefin production facilities were overcome, and domestic manufacturers accelerated their efforts in this area; these include companies such as Lanzhou Petrochemical, Satellite Chemical, Dingjide, Maoming Petrochemical, Jingbo Petrochemical, and Zhejiang Petrochemical. These companies are also developing integrated capacities for the expansion of POE production, and it is expected that China will enter a phase of capacity deployment after 2025.

α-Olefins are present in both the thermally processed products of petroleum distillates and those from catalytic cracking. However, the product composition is complex with numerous isomers, making it impossible to isolate the α-olefins. Before World War II, α-olefins were produced by the dehydration of primary alcohols obtained from the hydrogenation of vegetable oils. The resulting product has a high purity, but it is expensive. After the war, as demand for high-carbon olefins increased, inexpensive propylene and butylene from the catalytic cracking gases of oil refineries were used to produce C7, C9, and C12 branched olefins, which in turn were used to manufacture plasticizers and alkylbenzene sulfonate detergents. In the late 1950s, it was discovered that detergents made from branched olefins could not be degraded by microorganisms in water; after use, foam accumulated, sewers became clogged, and the quality of river water deteriorated. This has promoted the development of technologies for the production of straight-chain olefins. In the early 1960s, several methods for producing straight-chain α-olefins were developed. Detergents made from these α-olefins (see surfactants) exhibit good biodegradability, and they also have many other new applications.

As industrial products, α-olefins refer specifically to α-olefins with 5 or more carbon atoms, and are generally mixtures with a wide range of carbon counts (C6–C40). Straight-chain α-olefins with a carbon number range of C6 to C18 (or C20) have a wide range of applications. It is generally not separated into individual components, but is divided into various fractions according to the requirements of its use. If C6–C10 fractions are used to produce plasticizers, then C12–C14 and C16–C18 fractions are used to make detergents. C6–C18 α-olefins are all oily liquids.