At present, polypropylene (PP) is mainly produced by gas phase and bulk processes. The growth of global gas phase and bulk loop process resins strongly challenges the products of slurry process. Since the 1990s, the slurry process has been gradually eliminated. In the global PP production process, Basell’s Spheripol loop tube/gas phase process dominates, and this process currently accounts for 50% of the global PP production; followed by DOW’s Unipol gas phase process, BP’s Innovene gas phase process, and NTH’s Novolen Gas phase process, Hypol kettle body process of Mitsui, Borstar loop tube/gas phase process of Borealis, etc. In recent years, the ratio of gas phase and bulk process has increased year by year, and PP plants under construction and new construction all over the world will basically adopt gas phase process and bulk process. In particular, the rapid increase in gas phase processes is challenging the Spheripol process, which ranks first in the world. According to NTH Company, since 1997, 55% of the newly-increased PP capacity permitted worldwide has been based on the Novolen gas phase process, and the gas phase process will gradually increase in the future. In addition to the above main PP production processes, the original Montell company successfully developed reactor PP alloy Catalloy and Hivalloy technologies in the 1990s. The successful development of these two technologies has created conditions for the high performance, functionalization and entry of high value-added applications of PP resins, and industrial production has now been realized. In addition, Basell and Borealis have also made breakthroughs in new polypropylene technology.
(1) Hypol process of Mitsui Petrochemical. The Hypol process uses a kettle-type liquid-phase bulk-gas-phase combination process technology, and uses TK-II high-efficiency carrier catalysts. The catalyst activity is more than 20,000 gPP/gcat, and it does not remove ash and random substances. The isotacticity of PP is ≥98%, the particle size distribution is narrow, and a wide range of PP can be produced. The Hypol polypropylene process was first put into production in 1984 on two 40,000-ton/year production lines at the Chiba plant. There are 23 sets of production equipment and equipment under construction in the world using this process, with a total production capacity of 2 million tons/year. The polypropylene products produced by this process have many varieties, complete grades, high whiteness, good optical properties, low volatility and ash content, excellent product quality, and can meet all quality requirements without further processing. my country's Yangzi Petrochemical, Panjin Ethylene, Luoyang Petrochemical and Guangzhou Petrochemical all have this process equipment.
(2) Spheripol process of Haimont Company. The Spheripol process adopts a loop tube liquid phase bulk-gas phase combined process technology, using 10 kinds of high-efficiency carrier catalysts such as GF-2A, FT-4S, UCD-104, etc. The catalyst activity reaches 40,000 gpp/gcat, and the product isotacticity is 90%- 99%, no ash removal, no removal of random objects. This process uses new catalysts and new additives to add technology to develop a granulation-free Spheripol process technology. Compared with conventional production processes, equipment investment is reduced by 50%, energy consumption is reduced by 85%, and maintenance costs are reduced by 80%. The Spheripol process can produce a wide range of PP products, including homopolymers, random copolymers, terpolymers, multiphase impact copolymers and copolymers with high impact resistance with ethylene content greater than 25%. The catalyst particle size of the Spheripol process is large, round and uniform, so the polymer particles produced are large, in a granular shape, and a narrow particle size distribution. In addition, the material flow rate in the loop reactor is high, the apparent density of the generated powder is large and the surface is smooth, and it is not easy to be blown away by the airflow, which creates conditions for the application of the dense phase fluidized bed reactor. There are 43 sets of production equipment using this technology in the world, with a total production capacity of more than 6 million tons per year, including the total production capacity of devices under construction> 10 million tons per year. my country's Qilu Petrochemical, Shanghai Petrochemical, Wushun Ethylene, Maoming Petrochemical, Tianjin Lianhua, Zhongyuan, Dushanshan, Dalian, Huabei Oilfield, Daqing Refinery and other units all adopt this process for production.
(3) Unipol process of Union Carbide. The Unipol gas-phase fluidized bed process uses Shell’s SHAC high-efficiency catalyst with a catalyst activity of 2 to 25,000 gpp/gcat. The process of catalyst purification, deashing and random removal is omitted, the process flow is short, no waste liquid is discharged, and the pp isotacticity can reach 99%. This process technology is simple, economical and flexible, but has poor production stability and irregular product shapes. The world's total production capacity of production devices and devices under construction using this technology has increased to 5 million tons/year, second only to the Spheripol process, and the largest single-line production capacity can reach 320,000 tons/year.
(4) Amoco gas phase process. The Amoco gas phase process uses a horizontal stirred bed gas phase reactor with a reactor volume of up to 79 m2. Paddle stirring makes the material flow in the form of plug flow. The product is switched quickly. The polymerization heat is removed by the evaporation of propylene. The ultra-high activity carrier titanium series spherical catalyst is used. The catalyst activity reaches 40,000 gpp/gcat, and the PP isotacticity reaches 99%. The production process does not remove ash and random materials. It can produce homopolymers, random copolymers, and copolymers with high rigidity and high impact strength. The product quality is good and the production cost is low. Due to the use of paddle mixing, the material flows in the form of plug flow and does not require a large cycle, so it consumes less power, does not require steam, and is reliable in operation.
(5) Novolen gas phase process of BASF. The Novolen gas phase process adopts a double-spiral stirring vertical reactor with a lunar belt. The material flows in a turbulent state, and the catalyst is evenly dispersed in the powder bed. The first reactor produces homopolymers and random copolymers, and the second reactor Production of impact copolymers. Because it adopts the form of stirring and mixing, the residence time of the materials in the polymerization vessel is difficult to control uniformly, which makes the molecular weight of the product wider, the Ti, C1 ions and ash content in the product increase, and the catalyst activity is low. The advantages of this process are short surge and low investment. After switching to high-activity catalysts in 1990, the dechlorination treatment was omitted, and the production capacity was increased. The maximum single-line production capacity was 250,000 tons/year. The world's total production capacity using this technology has reached 3.8 million tons/year.
