By Zeng Xianfen, Oilchem

Heavy aromatics consisting of reformed C9 and industrial-grade C10 crude aromatics are by-products of continuous catalytic reforming (CCR) units. They are highly related with the refining and chemical integrated process. Reformed C9 containing a large amount of 1,2,4-trimethylbenzene, mesitylene, 1,2,3-Trimethylbenzene and ethyltoluene is mainly used to extract trimethylbenzene and 1,2,4-trimethylbenzene. Industrial-grade C10 crude aromatic is a mixture of hundreds of components, including 1,2,4,5-tetramethylbenzene and prehnitene, using to produce aromatic solvents with high boiling point and 1,2,4,5-Tetramethylbenzene etc.   

Supply

   By 2018, the total capacity of China’s CCR units reached 112.61 million t/a. Reformed C9 and industrial-grade crude C10 aromatics can be reserved for captive use as feedstock for gasoline and gasoil. Therefore, not all CCR units offer heavy aromatics in the commercial market for sales. In 2018, 2.23 million t/a of domestic heavy aromatics capacities were available for sales, while output and apparent consumption volume stood at 1.71 million tons and 1.81 million tons, respectively. The majority of the capacity was located in east and north China, with 980 kt/a and 550 kt/a, respectively. Table 1 shows China’s heavy aromatics capacity in 2018. 

   Table 1   China’s heavy aromatics capacity in 2018

   Domestic heavy aromatics supply increased sharply in 2019, by an estimated 220 kt/a, following the start-ups of the refining and chemical integrated projects at Dalian Hengli and Zhejiang Petrochemical and the commenced sales of products from CNOOC Huizhou Refinery and Fuhaichuang. Table 2 shows some of the new CCR capacities in China. 

   Table 2  Selected new CCR capacities in China during 2019-2022

   Reformed C9 is used to refine trimethylbenzene for gasoline blending and is also extracted to get 1,2,4-trimethylbenzene for Tri-Mellitic-Anhydride (TMA) production. Major consuming regions of reformed C9 include Shandong and Jiangsu, with Shandong Weisheng, Jiangsu Hualun and Jiangsu Zhengdan being main consumers, which together take up 60% of domestic consumption.  

   Industrial-grade crude C10 aromatic is mainly used to produce aromatic solvents with high boiling point for gasoline, gasoil and coating production. It is also extracted to get 1,2,4,5-tetramethylbenzene, which is used to produce pyromellitic dianhydride. Polyimide, yielded from pyromellitic dianhydride is applied in aviation industry and called as golden film. It is a big profit engine for industrial-grade crude C10 aromatic. Major consumption regions of industrial-use crude 10 aromatic include Jiangsu, Shandong and Hebei, with Jiangsu Hualun, Shandong Sai’er and Dagang Xingyuan being main consumers, contributing to 75% of domestic consumption.    

   The increase in consumption tax squeezed the margins of gasoline blenders and the feedstock purchase volume of most refiners. In addition, stricter environmental protection and safety supervision policies, as well as the elimination of backward low-end enterprises triggered continuous declines in coating output. They together dented trade of aromatic solvents with high boiling point and trimethylbenzene, thus capping the growth of heavy aromatics demand.  

Imports, exports and prices

   China had no heavy aromatics exported in 2018, as domestic supply was not enough to meet demand. Several domestic producers, including Jiangsu Hualun, Pengchen New Materials and Jiangsu Zhengdan imported a total of 100 kt of heavy aromatics originating from South Korea and Singapore in 2018. But with domestic supply increasing, China’s imports of heavy aromatics will decrease. 

   Domestic heavy aromatics prices fluctuated in an upward trend in 2019. The average price of reformed C9 stood at RMB5 146/t and that of industrial-use C10 crude aromatics was RMB4 505/t. Their yearly peak both hit mid-September at RMB6 287/t and RMB5 150/t, respectively, shored up by elevated gasoline prices. The yearly-trough of industrial-use C10 crude aromatics emerged in early April at RMB4 133/t, as supply increased after Dalian Hengli Petrochemical kicked off commercial sales, while downstream demand was sluggish. Reformed C9 prices dropped to the lowest level of 2019 in late January, at RMB4 433/t, because trimethyl-benzene producers cut prices in view of the slow end-user consumption from the gasoline market. 

   In the long term, heavy aromatics prices may hover at low levels as supply will increase but end-user demand is on the wane. Under such a circumstance, the heavy aromatics industry might move towards the refining development. Downstream producers shall take the initiative to develop new products and new production processes in such areas as prehnitene and further refine 1,2,4,5-tetramethylbenzene to enhance the products’ added value.