Inhibiting the polymerisation processes concomitant to the pyrolysis gasoline processing

摘要

It is known tat a feedstock consisting of alkanes, cycloalkanes and arenes with content of approximately 20% olefinic hydrocarbons and dienes is extremely unstable. The alkenes are most inclined to oxidation in strong relation to the structure of the hydrocarbon chain and the double bond location. It has been established that the oxidation is initiated by the hydrocarbons with conjugated double bonds or with one double bond in the side cain of the arene nuclei. The alkenes susceptibility to oxidation is increased when the hydrocarbon chain is more bifurcated and their double bond is adhering the molecular center. The pyrolysis gasoline (PG) and its distillate fractions composition contain a rather high level of reactable unsaturated compounds (diene, styrene, indene, etc.) inclined to polymerisation during processing and storage. the most important factors for the oxidation, condensation and polymerisation processes are temperature, oxygen presence, contact with metals and light access. As a results of these reactions insoluble high-molecular compounds, known as gums, originate even at the stage of storage and the problem is transferred to PG distillation and PG hydrogenation sections of the "Xylene" Plant. The present paper is aiming to avoid the above mentioned undesirable processes related to the feedstock used - pyrolysis gasoline to be processed in "Xylene" Plant.