C9 pyrolysis processing and utilization route

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First, various products are separated through distillation: DCPD and dimethylcyclopentadiene (DMCPD) can be separated; the alkylbenzene fractions can be hydrogenated to produce high-aromatic solvent oils and components for gasoline blending; styrene and indene fractions can be repolymerized to form petroleum resins; heavier fractions can be used to produce fuel or asphalt; naphthalene and methylnaphthalene can also be separated； The second method involves polymerization first followed by separation and hydrogenation; the monoenolic components in the C9 fraction are polymerized and separated to isolate unreacted substances as well as components with low boiling points, thereby yielding petroleum resin. During the production of petroleum resin, flash oil is generated, which can be converted into high-aromatic solvent oils and components for gasoline blending through hydrogenation ； Third is the direct hydrogenation to produce gasoline blending components. The main use of C9 is that the C9 fraction contains around 150 different chemical components; it has a high content of olefins, which makes it prone to polymerization. It also has a high gel content, with the various components being poorly dispersed and present in low concentrations. Moreover, their boiling points are very similar, making it difficult to utilize this material as a single component. From the perspective of synthetic chemistry, the components can be divided into two categories: active components (such as styrene, indene, and dicyclopentadiene), which are polymerized to form petroleum resins, or inert components, which are produced through hydrogenation ； Inactive components (alkylbenzenes and polycyclic aromatics such as indene, xylene, naphthalene, methylnaphthalene, etc.) are used as aromatic solvents or as raw materials for the production of p-xylene (PX). The main uses of C9 are as follows: 01 Production of C9 rosin. C9 rosin is a thermoplastic resin produced from the C9 fraction obtained as a by-product of petroleum cracking, through processes such as pretreatment, polymerization, and distillation. It does not belong to polymers; rather, it is an oligomer with a molecular weight ranging from 300 to 3000. Due to its low acid value, good miscibility, water and chemical resistance, as well as stable chemical properties, it is widely used in industries such as coatings, paints, and rubber as a catalyst, regulator, and modifier. However, the petroleum resin produced has a darker color and inferior performance, requiring hydrogenation treatment. Hydrogenation is difficult and costly, and the technology needs improvement. 02 In the production of C9 fractions using high-purity dicyclopentadiene (DCPD), the DCPD content is generally above 30%. High-purity DCPD is primarily used in the fine chemical industry, for applications such as polydicyclopentadiene materials, optical plexiglass materials, epoxy resins, as well as metal-organic compounds, chemical intermediates, the production of ferrocene, chemical additives, adamantane, glutaraldehyde, ethylene-propylene rubber, and the manufacture of high-energy fuels. 03 For the production of high-quality aromatic solvents, most companies first synthesize petroleum resins, or extract DCPD; after most of the active components are used up, the remaining components undergo hydrogenation in two stages to produce solvent oil. Alternatively, the components with a carbon number of C9 or higher can be processed by cutting them apart, removing gums, and reducing the levels of elements such as arsenic and sulfur; after undergoing a period of hydrogenation to saturate most of the olefins, they can be used as components in the formulation of high-octane gasoline ； After another stage of high-temperature hydrogenation to remove impurities such as sulfur and residual olefins, it can be used as a high-aromatic solvent oil or for the extraction of aromatics. Due to its high content of olefins, it polymerizes very easily; it also has high levels of arsenic and gums, making hydrogenation difficult. Process separation is required to remove the heavier components, which results in a loss of about 30% of the high-value aromatics. 04 Extraction of high-value single-component substances such as indene, xylene, naphthalene, methylnaphthalene, etc., and the utilization of carbon-9 tar.