Pyrolysis gasoline types

Enciforming [National Chemical reforming] A petroleum reforming process that converts pyrolysis gasoline to mixtures of propane, butane, and aromatic hydrocarbons, thereby obviating the usual hydrogenation and solvent extraction processes. The catalyst is a ZSM-5-type zeolite containing both iron and a platinum metal. Developed by the National Chemical Laboratory, Pune, India, since 1988, but not yet commercialized. 

Table Z2 lists the pyrolysis product yields for diffinent feedstocks treated at very high severity with recyde of the ethane produced or unconverted at the inlet of the reaction section. Indeed, ethane is an ideal raw material the formation of the lower olefins. It may be observed that the relative production of ethylene decreases as the feedstodc becomes heavier. Also worth noting is that the ratio of Uie ethylene and propylene yidds (C2/CJ ratio) decreases steadily from ethane to the gas oils, whereas the percentage of pyrolysis gasoline (Cs 200 C cot) increases simnltaneously. As to the butadiene yield, thb varies slightly with the type of feedstock in the treatment of liquid petroleum fractions.

Indications are given in Tables 4.13 and 4.14 for the main industrial processes. They vary widely according to the type of feed considered (toluene, aromatics blends, pyrolysis gasolines etc.) and the composition and conditions of supply of the hydrogen gas employed. 

Table 4.2 Properties of pyrolysis gasolines in relation to type of cracking...

Different types of polymer degrade into liquid products at different temperature and form hydrocarbons with structural differences according to the structure of the parent polymer. The liquid hydrocarbons obtained by pyrolysis of PE are widely distributed from C3 to C25 and are composed of linear olefins and paraffins. The liquid hydrocarbons obtained from pyrolysis of PP are also distributed in the range C3-C25, but the gasoline fraction obtained in PP pyrolysis has a higher octane number compared with gasoline obtained from PE pyrolysis. 

Py-GC/MS of samples (prepared as were the ICM samples) of the four materials thought to be the major sources of the tunnel air particulates — tire rubber, road salt, diesel exhaust, and gasoline exhaust — showed that road salt gave no pyrolysis products and the other three materials gave pyrograms of complexity similar to those of the ICM samples. The overlap of compound types and the absence of unique marker compounds made an assessment of the relative contribution of each of the three sources to the total impractical using the Py-GC/MS profiles. 

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