Overview of the Applications of Petroleum Carbon 9

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I. Overview of C9 hydrocarbons: C9 hydrocarbons refer primarily to the fraction containing nine carbon atoms that is a byproduct of catalytic reforming and ethylene cracking. This C9 fraction is composed of more than 150 different chemical compounds, including n-propylbenzene, isopropylbenzene, ethyltoluene, p-xylene, m-xylene, o-xylene, and indene. In recent years, China’s carbon nine resources have been around 3 million to 4 million tons per year, with the main sources being reforming and ethylene cracking units. Reforming naphthane is primarily achieved through catalytic reforming and aromatic extraction units, with benzene, toluene, and xylene being separated to yield the by-product naphthenic aromatic fraction ； Furthermore, in units for increasing xylene production through processes such as the disproportionation and alkylation transfer of carbon 7 to carbon 9 aromatics, xylene is separated, yielding the by-product of carbon 9 aromatic fraction. The carbon nine components produced through ethylene cracking are highly complex and dispersed; it is difficult to utilize individual components, and it is almost impossible to separate them clearly. At present, research institutions at home and abroad can only roughly separate pyrolyzed carbon-9 into active and inactive components before utilizing them comprehensively. II. Applications of reformed carbon nine and its production: The aromatic composition of reformed carbon nine is relatively simple, comprising components such as p-xylene, o-xylene, m-xylene, and para-xylene. These components are valuable resources for the fine chemical industry and possess high economic value. The reformed carbon nine aromatics produced by China’s refining and chemical enterprises contain almost no olefins, and their components have good stability; separating these components can yield excellent economic benefits. Pentamethylbenzene: In the reformed C9 fraction, pentamethylbenzene can be used primarily in the production of synthetic resins, antioxidants, highly effective herbicides for fields, plasticizers for alkyd resins, curing agents for epoxy resins, intermediates for dyes in the dye industry, pentamethylbenzoic acid, urethane coatings, as well as in pharmaceuticals and photographic materials. Trimethylbenzene has a high demand in China, and its market prospects are promising. Currently, the production of p-xylene in China mainly relies on the isomerization method represented by Jinling Petrochemical, and the alkylation method represented by Tianyuan Company of Jinzhou Petrochemical. P-xylene: Reformated C9 p-xylene is widely used in the fields of paints, coatings, synthetic resins, resin processing, pharmaceuticals, and cosmetics. The commonly used production method is double-column distillation, and major manufacturers include Jinling Petrochemical, Jinzhou Petrochemical, Fushun Petrochemical, Jiujiang Petrochemical, etc. Trimellitic anhydride: It is primarily used in the production of aniline dyes, alkyd resins, polyester resins, as well as trimellitic acid, jet fuel additives, and synthetic musk. The main method for its production is precise distillation. Currently, only the American company KOCH produces high-purity trimellitic anhydride; in China, however, little attention has been paid to the development of this substance. Methyl ethyl benzene: Methyl ethyl benzene can be used to produce thermoplastic resins, poly**ethylene monomers, paint drying agents, wood preservatives, as well as raw materials for synthetic detergents and insecticides. At present, the production and utilization of methyl ethyl benzene in China are still at a relatively weak level. III. Applications and Production of Pyrolyzed Carbon 9 According to statistics from \"Petroleum and Petrochemical Industry News,\" as of May 2015, China’s ethylene production capacity had reached 22.97 million tons per year, with the production of pyrolyzed carbon 9 amounting to approximately 2.2 million tons per year. The composition of pyrolyzed C9 is very complex, with a high content of unsaturated hydrocarbons, and it is difficult to separate individual components; therefore, a comprehensive utilization approach must be adopted. Pyrolyzed nonafluorocarbon is mainly used in the production of high-quality aromatic solvents, aromatic resins, nonafluorocarbon resins, high-purity dicyclopentadiene, styrene, toluene, ethylbenzene, and other substances. Due to the highly complex composition of pyrolyzed nonafeulene, only components such as styrene, dicyclopentadiene, vinyl toluene, and indene can be separated ； The current mature and applicable method is to use it without separation, directly producing aromatic petroleum resins from its mixed components. Aromatic resin: An aromatic resin is a functional resin that ranges in color from light yellow to dark brown. Due to the absence of polar groups in its structure, it exhibits good water resistance, acid and alkali resistance, weather resistance, and resistance to photo-aging. It has good solubility in organic solvents, especially petroleum-based solvents, and is compatible with other resins. It also possesses properties such as brittleness, viscosity-increasing effect, adhesiveness, and plasticity, and is widely used in the coating industry, ink industry, papermaking industry, and plastics industry. Dicyclopentadiene: High-purity dicyclopentadiene has active polymerization properties. By using dicyclopentadiene as the main material and employing reactive injection molding, it is possible to produce large quantities of thermosetting cross-linked polydicyclopentadiene resin products in complex shapes within a very short time. Its products are used for the exterior covering components of equipment such as automobiles, construction machinery, agricultural equipment, and medical devices. The production of high-purity dicyclopentadiene primarily relies on the liquid-phase depolymerization method. Styrene: Styrene is primarily used in the production of chemical products such as phenol propyl ethers, styrene-butadiene copolymers, styrene-isoprene-styrene block copolymers, styrene-butadiene rubber, and polystyrene. It is mainly produced through the process of cracking naphtha followed by extraction and distillation. IV. Key Research Institutions in the Application Chemistry of Carbon 9 In China, the main research and development institutions focused on the industrial applications of carbon 9 include: 1) Beijing Yanhua High-Tech Co., Ltd.; 2) Shanxi Coal Chemistry Institute of the Chinese Academy of Sciences; 3) Yanshan Branch of Sinopec; 4) Petrochemical Technology Development Center of Tianjin University