Sub-Product

С₅ Pygas is a Byproduct of the Pyrolysis Process of Petroleum fractions. It is a highly volatile Hydrocarbon Liquid that boils within 30-70°C and is separated by Distillation of Benzene from Pyrolysis Gasoline.

It contains a lot of unsaturated compounds. Besides С₄-С₅ Olefins, the С₅ cut also includes Dienes (Butadiene, Isoprene, 1,3-Pentadiene, Cyclopentadiene and others, Dicyclopentadiene, significant amounts of Acetylenics (Butyne-2). Moreover, there are Sulfur and Oxygen (mainly Carbonyl) Compounds.

A typical composition (in % mass units) is provided according to:

• Hydrocarbons С₄ and lighter: 0.9-4.2
• Parafins С₅: 23.1-29.1
• Olefins С₅: 14.7-25.1
• Dienes С₅, including: 1,3-Pentadiene (Piperylene): 6.7-12.4
• Isoprene: 23.0-26.3
• Cyclopendiene + Dicyclopentadiene: 11.7-17.8
• Hydrocarbons С₆ and heavier: 0.5-2.7
• Oxygen Compounds: 0.13-0.2
• Butyne-2: 0.8-3.5

Because of the high content of Di-olefinic Components, C₅ Pygas reacts readily with other Components.

C₅ Pygas is used as a source for Isoprene to make Polyisoprene Rubber for Tires. The stream also contains Piperylene used to produce Copolymerisation Elastomers, Petroleum Resins, Curing Agents, Pesticides and Perfumes. It may also be used as Gasoline Blending Component.

References:

1. I.R. Khasanov, A.M. Kiryukhin, D.N. Munasypov, Z.D. Fedorova, C₅ PYGAS PURIFICATION FROM UNSATURATED HYDROCARBONS, Electronic scientific journal "Oil and Gas Business", 2014, N°3.
2. DOW, C-5 DIENES CRUDE Technical Data Sheet