The industrialization of high-carbon α-olefins needs to be accelerated

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The industrialization of high-carbon α-olefins needs to be accelerated □ Cao Shengxian, Daqing Chemical Research Center, China National Petroleum Corporation Research Institute of Petroleum and Petrochemicals. α-Olefins generally refer to high-carbon linear olefins with 4 carbon atoms or more; they are an important organic chemical raw material that has seen rapid development over the past 30 years. The main applications of α-olefins fall into five categories: (1) Copolymer monomers. The copolymer monomers used in the production of LLDPE and HDPE are primarily 1-butene, 1-hexene, and 1-octene; over 40% of α-olefins are used as copolymer monomers for PE ； (2) Used in detergents and detergent alcohols; detergent alcohols synthesized from α-olefins exhibit excellent biodegradability ； (3) Synthetic lubricants: Polyalpha-olefins are high-quality synthetic lubricants, primarily being oligomers of 1-decene and 1-octene ； (4) Plasticizer alcohols: These are plasticizer alcohols obtained through carbonylation of C8-C10 linear α-olefins; they have low volatility and excellent light stability as well as antioxidant properties ； (5) Used in lubricant additives as well as drilling fluids, adhesives, sealants, etc. Production and technology are concentrated in Europe and the United States. 1. The main application area is monomers for copolymerization. In 2008, the global total production capacity for 1-octene was 664,100 tons per year; the main manufacturers and their production capacities are shown in Table 1. North America accounts for about 50% of the world’s total production capacity for 1-octene, Western Europe for about 20%, South Africa for about 17%, Eastern Europe for about 7%, and Asia for about 6%. 1-Octene accounts for 56% of global consumption as a comonomer in the production of LLDPE. In terms of geographical distribution, approximately 47% of 1-octene in the United States is used in LLDPE production, 46% in Western Europe, 80% in Asia-Pacific, and 86% in Japan. Other uses include plasticizers accounting for 33%, surfactants 4%, pulp and paper 3%, lubricants 2%, synthetic acids 1%, and α-olefin epoxides and rubber processing aids at 0.5% each. 　　2. Comparison of main production processes The main methods for producing α-olefins include wax cracking, alkane dehydrogenation, ethylene oligomerization, and extraction separation. Currently, the ethylene oligomerization method is the primary approach for producing α-olefins, with α-olefins manufactured using this method accounting for 94.1% of the total production of α-olefins. 　　The companies that currently possess ethylene oligomerization technology include Chevron Phillips in the United States, Shell in the Netherlands, BP Amoco in the United Kingdom, and Idemitsu in Japan, among others. The Shell, Chevron, and BP Amoco processes are the earliest and most typical homogeneous ethylene oligomerization processes. The target products of these three processes are C4–C30 α-olefins; among them, Shell’s product quality is the best, but its process route (which includes steps such as disproportionation and isomerization in addition to oligomerization) is the longest, resulting in the highest production costs ； Chevron’s product quality is relatively good, and its production costs are the lowest due to its simple process (the oligomerization reaction takes place in one step); however, its operating conditions are the most stringent (high temperature and high pressure) ； The product quality of BPAmoco processes is poor, but their carbon number distribution is relatively narrow; in particular, their newly developed full-cycle 1-butene process results in a significant increase in the proportion of C6–C10 α-olefins. The main disadvantages of these three processes are a wide carbon number distribution and low catalyst activity per pass. In particular, the harsh operating conditions (with pressures around 20 MPa) result in high equipment costs and operational difficulties, as well as significant safety issues. Furthermore, the Chevron and Ethyl methods also have the disadvantages of difficult separation of the product from the catalyst and hard-to-treat waste liquids. 　 Phillips’ ethylene trimerization process uses a unique chromium-based catalyst, resulting in a narrow product distribution; it primarily produces 1-hexene for use as a polyethylene monomer, with a selectivity for hexene of 90% to 95%, and 1-hexene accounts for about 99% of the hexene produced. Additionally, this process can also produce 9% to 15% C10 α-olefins. Compared with the aforementioned process, this new process is characterized by a relatively narrow carbon number distribution, increased production flexibility, and milder operating conditions; however, it still faces issues such as a low one-pass conversion rate and the need to separate and recover the catalyst. 　　In addition to the processes mentioned above, companies such as Idemitsu in Japan and Linde in Germany also possess their own patented technologies for ethylene oligomerization. Examples include Idemitsu’s zirconium-aluminum catalytic process, as well as the Alpha-Sablin technology developed jointly by Linde and Saudi Basic Industries Corporation (SABIC). However, the scale of production using these technologies is currently relatively small. 　 In addition, Sasol Chemicals has also successfully developed a production process for the selective manufacture of 1-octene, a process that relies on Fischer-Tropsch synthesis at high temperatures to produce hydrocarbons with a high alpha-olefin content following a Anderson-Schulz-Flory distribution. 1-Octene can also be obtained from 1-heptene through olefin homologation reactions. Table 1: Major global producers of 1-octene in 2008 and their production capacities in 10,000 tons per year. Company | Location | Production Capacity
Chevron Phillips | Texas, USA | 9.85
Godrej Industries | Bharuch, India | 1.14
Idemitsu Kosan | Chiba, Japan | 1.50
INEOS | Faluy, Belgium | 7.64
INEOS | Alberta, Canada | 7.00
Mitsubishi Chemical | Mihara, Japan | 1.09
Nizhnekamskneftekhim | Nizhnekamas, Russia | 4.09
Sasol | Secunda, South Africa | 10.00
Shell Chemicals | Louisiana, USA | 13.39
Shell Chemicals | Stanlow, UK | 5.16
SABIC | Saudi Arabia | 3.00
Iranian Petrochemical Company | Iran (under construction) | 2.55
Slow industrialization at home
With the rapid development of the PE industry, the demand for α-olefins, particularly 1-hexene and 1-octene as high-grade α-olefins, is increasing steadily. Among them, PE copolymerized with 1-hexene is the variety with the fastest growing demand at present; approximately 94% of the new PE products developed by foreign companies use 1-hexene as a comonomer, while PE using 1-octene as a comonomer already accounts for 30% of the total production. 　　Two 1-hexene production facilities have already been built and put into operation in the country. Sinopec’s first industrial production facility for 1-hexene with a capacity of 5,000 tons per year utilized a process technology for the polymerization of ethylene to produce 1-hexene, which was independently developed by the Daqing Chemical Research Center and holds independent intellectual property rights. This facility was fully built and put into operation at Daqing Petrochemical Company in 2008, and it has since produced qualified products. In addition, Yanshan Petrochemical’s 50,000 t/a industrial production facility for 1-hexene was put into operation in 2007. The commissioning of these two sets of facilities will not only help alleviate the shortage of 1-hexene in the domestic market, but also further optimize the company’s polyethylene product portfolio, enhancing the quality of its polyethylene products and their competitiveness in the market. 　　At present, China’s synthetic resin and plastic industry is developing rapidly. However, due to a severe shortage of domestically produced 1-hexene and 1-octene copolymer monomers, many HDPE and LLDPE production facilities still use 1-butene as the copolymer monomer. This results in problems such as lower quality of polyethylene products, unreasonable structures, and a shortage of specialized grade products. Although 1-hexene production facilities have been put into operation over the past two years, there is still a significant gap in the market. In 2006, China’s LLDPE production was over 2.3 million tons; assuming a 30% proportion of materials used for this purpose, the demand for 1-hexene could reach 70,000 tons. Moreover, with the ongoing development of high-quality HDPE products synthesized using 1-hexene as a comonomer, the demand for this comonomer will only increase further. At the same time, there are no industrial facilities for 1-octene in China to date, and the product relies entirely on imports; the country needs to import approximately 40,000 tons of 1-octene each year. Therefore, accelerating the development and industrial production of α-olefin synthesis technology in our country is of great significance for improving the overall level of the PE industry. 　　Secondly, the quality level of lubricant products also has a significant impact on an entity’s energy consumption levels. Taking category IV base oils synthesized from C8–C12 (especially C10) α-olefins, namely polyα-olefins (PAO), as an example, their excellent overall performance gives them advantages over other mineral base oils in terms of reducing friction and wear, improving fuel efficiency, extending the service life of equipment and the interval between oil changes, as well as minimizing environmental pollution. At present, the majority of high-end lubricants offered by major lubricant manufacturers around the world use fully synthetic base oils. Approximately 94% of the PAO used as base oils for lubricants in China is imported, while the remaining 6% is low-quality PAO produced domestically through wax cracking. Furthermore, α-olefins have important applications in industries such as daily chemicals, fragrances, and papermaking. The shortage of high-quality α-olefins also significantly hinders the development of China’s fine chemical industry as well as the market competitiveness of related enterprises. Therefore, the industrialization of high-carbon α-olefinic acids still needs to be advanced.