Alkyl aromatics from catalytic cracking

The liquid products of catalytic cracking (obtained in accordance with the described principles) have been omitted from consideration thus far, except in the case of the alkyl aromatics. To the refiner, the liquid obtained is of prime importance, both as gasoline and heavier intermediate oils. 

Saturated constituents contribute less to the vacuum gas oil than the aromatics but more than the polar constituents that are now present at percentage rather than trace levels. The vacuum gas oil itself is occasionally used as heating oil but most commonly it is processed by catalytic cracking to produce naphtha or by extraction to yield lubricating oil. Within the vacuum gas oil saturates, the distribution of paraffins, /iso-paraffins and naphthenes is highly dependent upon the petroleum source. The bulk of the vacuum gas oil saturated constituents consist of /Iso-paraffins and naphthenes. The naphthenes contain from one to more than six fused rings and have alkyl substituents. For mono- and di-aromatics, the alkyl substitution typically involves one long side chain and several short methyl and ethyl substituents. 

Catalytic Cracker Bottoms (CCB) which is the heavy residue from the catalytic cracking of petroleum distillate is a common aromatic feedstock used for synthetic carbons and pitch production. CCB, like other heavy aromatic feedstock, is composed of alkyl-substituted polycondensed aromatics with a very wide molecular weight distribution. 

Refining of the catalytically cracked aviation base stock was at first done with sulfuric acid, merely to remove unsaturates (133). However, it was found that passing the raw aviation fraction a second time over the cracking catalyst (catalytic re-treating) resulted in a product with less olefins, more aromatics, and improved response to tetraethyllead, and thus decreased sharply the proportion of alkylate required in the aviation blend (51). These effects are illustrated in Table VII. The effect of retreating a naphtha from a high-temperature first-pass operation is shown in Table VIII, and the quality of the aviation base stock is compared... 

Catalytic Reforming. Worldwide, approximately 30% of commercial benzene is produced by catalytic reforming, a process ia which aromatic molecules are produced from the dehydrogenation of cycloparaffins, dehydroisomerization of alkyl cyclopentanes, and the cycHzation and subsequent dehydrogenation of paraffins (36). The feed to the catalytic reformer may be a straight-mn, hydrocracked, or thermally cracked naphtha fraction ia the... 

MBR [Mobil benzene reduction] A catalytic process for reducing the benzene content of gasoline. It combines features of three earlier processes benzene alkylation with tight olefins, olefin equilibration with aromatization, and selective paraffin cracking. The olefins are obtained from FCC offgas. The catalyst is a modified ZSM-5 zeolite. Developed by Mobil Research Development Corporation in 1993. 

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