Introduction to the main polyethylene production technologies worldwide

(1) The gas-phase Spherilene process of Basell Company enables the production of linear PE ranging from very low-density PE (ULDPE) to LLDPE, as well as HDPE and others. Ziegler-Natta-type titanium-based catalysts and the Spherilene gas-phase process are used. In the presence of light inert hydrocarbons, the catalyst and feed undergo bulk pre-polymerization first, with bulk polymerization taking place under mild conditions. The slurry enters the first gas-phase reactor, where it is cooled by a circulating gas loop cooler, before proceeding to the two subsequent gas-phase reactors. The density of the produced products ranges from ULDPE (less than 900 kg/m3) to HDPE (more than 960 kg/m3), while the melt flow rate (MFR) ranges from 0.01 to 100. By using two gas-phase reactors, bimodal and specialty polymers can be produced. Since the Spherilene process was introduced to the market in 1992, it now has a production capacity of 1.8 million tons per year. Six production units (1 in the United States, 2 in South Korea, 2 in Brazil, and 1 in India) are already in operation, with another two (one in India and one in Iran) under construction. The annual production capacity per unit ranges from 100,000 tons to 300,000 tons. At present, China does not have production facilities for such technology.

(2) Bastar process of Nordic Chemicals: The Bastar PE process can produce bimodal and unimodal LLDPE, MDPE (medium-density PE), and HDPE. A series-connected loop and a low-pressure gas-phase reactor are used. The PE density is 918–970 kg/m3, with a melt index of 0.1–100. Z-N catalysts or SSC (single active center) catalysts are used. The catalyst and propane diluent are mixed and fed into a compact prepolymerization reactor, along with the co-catalyst, ethylene, comonomer, and hydrogen. The pre-polymerized slurry then enters a second, larger slurry loop reactor, which operates under supercritical conditions (75–100°C, 5.5–6.5 MPa). Bimodal-grade products can be produced. The flashed polymer is further fed into a fluidized-bed gas-phase reactor; without the need to add new catalyst, a homopolymer can be obtained. The operating conditions for the gas-phase reaction are: 75–100°C and 2.0 MPa. The first set of industrial plants was put into operation in Finland in 1995, while the two production lines built in Abu Dhabi (with a capacity of 450,000 tons per year for bimodal products) were commissioned in the second half of 2001. The fifth set of plants with a capacity of 250,000 tons per year (the second set of bimodal type) was also built at Sinopec in Shanghai, becoming China’s largest PE production facility; the maximum designed capacity for each production line in this process is 300,000 tons per year.

(3) BP’s gas-phase Innovene process can produce LLDPE and HDPE products, using Z-N titanium-based, chromium-based, or metallocene catalysts. Chromium catalysts can produce products with a wide molecular weight distribution, while Ziegler-Natta (Z-N) catalysts produce products with a narrow molecular weight distribution. The operating conditions of the bed reactor are mild, at 75–100°C and 2.0 MPa. Butene or hexene can be used as comonomers. 30 production lines are already in operation, under design, or in construction. The capacity range is 50,000–350,000 tons per year. Technip collaborates with BP to license BP’s Innovene process for producing polyethylene in Europe, the former Soviet Union, South America, China, and Malaysia. BP’s Innovene PE capacity now exceeds 8 million tons per year, including PE plants in Bandar Imam in Iran, Grangemouth in Scotland, Merak in Indonesia, and Kertih in Malaysia. The second expansion of the LLDPE/HDPE plant at China’s Dushanzi Petrochemical Company also adopted the Innovene process, increasing production capacity from 120,000 tons per year to 200,000 tons per year. Sinopec’s newly built 600,000-ton polyethylene plant will utilize this technology.

(4) ExxonMobil’s tubular and batch reaction processes utilize high-pressure free radical technology to produce LDPE homopolymers and EVA (ethylene vinyl acetate) copolymers. Large-scale tubular reactors (capacity of 130,000–350,000 tons per year) and stirred-tank reactors (capacity of about 100,000 tons per year) are used. The operating pressure of tubular reactors can reach up to 300 MPa, while that of batch reactors is below 200 MPa. The advantage of high-pressure processes is the reduction of residence time, allowing the same reactor to switch from producing homopolymers to copolymers. The density of the homopolymer is 912–935 kg/m3, and its melt index ranges from 0.2 to 150. The vinyl acetate content can be as high as 30%. The material and energy consumption per ton of polymer produced is as follows: 1.008 tons of ethylene, 800 kwh of electricity, 0.35 tons of steam, and 5 m3 of nitrogen. 23 high-pressure reactor units have been put into operation, with an annual production capacity of 1.7 million tons. Produces homopolymers and various copolymers. The newly built 200,000 tons/year LDPE plant in Yanshan currently utilizes this company’s tubular process technology.

(5) Mitsui Chemicals’ low-pressure slurry CX process can produce HDPE and MDPE; this process utilizes the low-pressure slurry CX method. Products with a bimodal molecular weight distribution can be produced. Ethylene, hydrogen, comonomers, and ultra-highly active catalysts enter the reactor, where polymerization occurs in a slurry state. The automatic polymer property control system can effectively control the product quality; there is no need to remove the ultra-highly active catalysts from the product. 90% of the solvent separated from the slurry can be directly recycled to the reactor without any treatment. Products with a narrow or wide molecular weight distribution can be produced, with a density of 930–970 kg/m3 and a melt index of 0.01–50. The material and energy consumption per ton of product is as follows: 1,010 kg of ethylene and comonomers, 305 kWh of electricity, 340 kg of steam, 190 tons of cooling water, and 30 m³ of nitrogen. 35 production lines have been put into operation or are under construction, with a total capacity of 3.6 million tons per year. In China, the main enterprises utilizing this technology currently include a 220,000-ton plant in Daqing, 140,000-ton plants in Yangzi and Yanshan, and a 70,000-ton plant in Lanzhou.

(6) Chevron-Phillips two-loop reactor LPE process: Linear polyethylene (LPE) is produced using Phillips Petroleum’s LPE process. Polymerization is carried out in a loop reactor and isobutane slurry using a highly active catalyst. The product melt index and molecular weight distribution can be adjusted and controlled by the catalyst, operating conditions, and hydrogen. Copolymerizable monomers can include butene-1, hexene-1, octene-1, etc. The highly active catalyst eliminates the need for catalyst removal, and no paraffin or other by-products are generated during polymerization, **reducing environmental pollution from emissions. Ethylene, isobutane, comonomers, and catalyst continuously enter the loop reactor, where they react at below 100°C and about 4.0 MPa, with a residence time of approximately 1 hour. The one-way conversion rate of ethylene exceeds 97%. The material and energy consumption per ton of product produced is as follows: 1.007 tons of ethylene, 2–10 dollars for catalysts and chemicals (depending on the product), 350 kwh of electricity, 0.25 tons of steam, 185 tons of cooling water, and 30 m3 of nitrogen. 82 production lines have been put into operation or are under construction, accounting for 34% of the world’s PE capacity. Shanghai Jinfei Company’s 135,000-ton plant utilizes this technology. The newly built 350,000 tons per year plant in Maoming may also adopt this technology.

7) Univation Technology’s low-pressure gas-phase Unipol process uses low-pressure gas to produce LLDPE-HDPE via the UnipolPE process. Slurry catalysts as well as gas-phase and fluidized-bed reactors are used. Conventional metallocene catalysts can be used without a catalyst removal step. The investment and operation costs are low, and it causes less environmental pollution. Ethylene, comonomers, and catalyst are fed into the fluidized bed reactor under operating conditions of about 100°C and 2.5 MPa. The product density is 915–970 kg/m3, with a melt index of 0.1–200. The narrow or wide molecular weight distribution can be adjusted depending on the catalyst type. 89 production lines have been put into operation or are under construction. The single-line capacity can range from 40,000 to 450,000 tons per year. Currently, there are many facilities in China that use this technology, mainly in Maoming, Jihua, Yangzi, Tianjin, Zhongyuan, Guangzhou, Daqing, Qilu, and other places.

(8) Stamicarbon’s COMPACT process: This process uses advanced Z-N catalysts along with the COMPACT Solution technology to produce PE with a density of 900–970 kg/m3. A stirred-tank reactor is used, with a polymerization temperature of 200°C. Hydrogen is used to control the polymer molecular weight. There is no need for a catalyst removal step. The material and energy consumption per ton of product produced is as follows: 1.016 tons of ethylene and comonomers, 500 kWh of electricity, 400 kg of steam, 230 m3 of cooling water, and 330 kg of low-pressure steam (as a by-product). Five units have been put into operation, with a total capacity of 650,000 tons per year.

(9) The Hostalen process of Basell Polyolefins – HDPE is produced using a stirred-tank reactor in the Hostalen process. Slurry polymerization is carried out using two reactors in parallel or in series. The material and energy consumption per ton of product is as follows: 1.015 tons of ethylene and comonomers, 400 kg of steam, 350 kWh of electricity, and 165 m³ of cooling water. Currently, 31 production lines are in operation or under construction, with a production capacity of nearly 3.4 million tons per year. Currently, the only facility in China using this technology is Liaohua Company, with a production capacity of only 40,000 tons. At present, this technology allows for a maximum production capacity of 350,000 tons per year per line, and it can produce almost all types of products, including bimodal ones.

There are no network-type catalysts; only chromium-based catalysts exist. In addition to the gas-phase process, Basell also has the Hostalen process, as well as tubular and autoclave-based high-pressure polyethylene processes, which are much better known than its gas-phase process. Chevron-Phillips two-loop reactor LPE process. . Chevron Phillips is strictly speaking HDPE, not LPE; the comonomers that can be used include butene-1, hexene-1, octene-1, etc. In the Maoming plant, only hexene-1 is used as a comonomer, and that plant has been in operation for 10 years now – your data is too outdated, with obsolete operating temperature ranges. :D produces HDPE using the Hostalen process in a stirrer tank. Slurry polymerization is carried out using two reactors in parallel or in series. How come there are three reactors connected in series? Moreover, in China, there isn’t just the 40,000 tons per year production facility at Liaoning Chemicals; Jilin Chemicals and Pengzhou Petrochemical also have such facilities. Stamicarbon’s COMPACT process cannot be considered a major process at all – it’s too niche.; It’s not even on par with Ineos’ processes. Actually, this explanation is rather confusing. There are two main categories: High-pressure polyethylene/EVA: tubular and batch processes; Low-pressure polyethylene: fluidized bed, loop reactor, and batch processes. Or perhaps this category can be further divided into linear polyethylene and high-density polyethylene