中国PAO产业正在蓬勃发展

【导读】煤制油生产者山西潞安集团今年计划上线一个年产3000吨低粘度PAO的工厂，加速了中国PAO产业的蓬勃发展。潞安集团现有产品线的年产能为50,000吨，其中PAO的年产能为23,000吨。其中20,000吨为高粘度PAO（40-200cst），剩余3,000吨为低粘度（4--10cst）。

The coal_to_liquids base oil operations that Shanxi Lu’an Group opened in Shanxi, China, last month included a plant with capacity to make 23,000 metric tons per year of high_and low_viscosity polyalphaolefins, adding to China’s blossoming supply of PAO.

The company, which is one of the country’s largest coal suppliers, also opened a larger plant that makes API Group III base stocks.

The base oil facilities are part of a pre_existing coal_to_liquids refining complex with overall capacity to make 1.8 million tons per year of CTL products. The complex uses Lu’an’s own cobalt_based Fischer_Tropsch process to synthesize coal and natural gas into liquids, General Manager Liu Junyi said in response to questions e-mailed by Lube Report.

The process produces olefins_or alkenes, chains of unsaturated hydrocarbons of varying lengths. The company uses a purification process to extract those in the C2 to C20 (which refers to the number of carbon atoms) range and synthesizes them to make PAO, diesel, gasoline, kerosene and other fuel products.

Capacity for that combined product stream is 50,000 t/y, Li said, including 23,000 t/y of PAO. Of the latter amount, 20,000 t/y are high_viscosity PAO (ranging from 40 to 200 centiStokes) and 3,000 t/y are low vis (4 to 10 cSt). The lubricants industry uses high_vis PAO primarily as additives for viscosity modification and viscosity index improvement, while low_vis PAOs are used as high_performance synthetic base stocks.

Lu’an said its ability to make low_vis CTL PAOs is an innovation achieved through a process developed in partnership with the Li Juisheng, of the Shanghai Advanced Research Institute, part of the Chinese Academy of Sciences. China produces substantially less low_viscosity PAO than it uses, and its lubricants industry relies largely on imports.

The complex’s waxy CTL output olefins longer than C20 are used to make Group III base stocks through a onestep olefin production process. That production stream has capacity of 300,000 t/y.

Lu’an’s Li described the PAOs produced at the complex as alkanes with flash points of 280 degrees C and cold cranking simulator scores of up to 1,600 milliPascals per second at minus 35 C. The Group III oils are branched chain alkanes with flash point above 200 degrees.

Lu’an and Naco Lubrication Co. already had a 50_50 joint venture that operates a 15,000 t/y CTL PAO plant in Shanxi. Naco operates another 15,000 t/y PAO plant in Shanghai. Shanghai Fox Chemical operates a PAO plant in Nanjing.

China now ranks second globally_behind only the United States_in the number of PAO plants. China’s plants are smaller than most in the industry, though, so Belgium and France have more capacity.