METHOD OF INCREASING QUALITY OF SULFUR-CONTAINING FRACTION OF RAW MATERIAL (VERSIONS) Russian patent published in 2002 - IPC

FIELD: petrochemical processes. SUBSTANCE: low-sulfur gasoline is obtained from olefin sulfur-containing cracking ligroin (naphtha) by treatment with acid catalyst, preferably zeolite with middle pore size such as ZSM-5 for cracking of low-octane paraffins and olefins under rather mild conditions at limited aromatization of olefins and naphthenes. The following step is hydrodesulfurization catalyzed by hydrofining catalyst such as CoMo/alumina. In the first treatment stage involving acid catalyst, olefins, which would be saturated in the hydrodesulfurization stage to lower octane number of product, are converted into compounds favorably contributing to anti-knock properties of products. Total yield of liquid products us high, commonly at least 90%. Level of aromatic hydrocarbons in products increases generally no more than by 25% and can even be lower than in raw material. EFFECT: reduced sulfur level to acceptable value at no loss in octane number. 10 cl, 3 tbl, 4 ex