Method for producing non-carcinogenic aromatic process oil
The present invention relates to the chemical or petroleum-processing industry and can be used in the production of petroleum plasticizers for synthetic rubber and tyres. In the method for producing non-carcinogenic aromatic process oil, containing a PCA extract of less than 3.0% according to the IP-346 method, said method comprising purifying the oil fractions of petroleum with selective solvents and separating the extract, additionally processing the extract with a polar solvent and producing a raffinate as the end product, the polar solvent used is a mixture of dimethylsulphoxide and Nmethylpyrrolidone, which is used for preliminary processing of the extract, wherein, after the preliminary processing, the mixture of extract and polar solvent is filtered, divided and the light phase is sent to the additional processing of the extract with the polar solvent, and the heavy phase is sent to a polar solvent regeneration stage. The ratio of dimethylsulphoxide to N-methylpyrrolidone in the mixture is within the range of 1:0.1-0.5. The ratio of polar solvent to extract in the additional processing stage is within the range of 1.5-2.5:1. The ratio of polar solvent to extract in the preliminary processing stage is within the range of 0.1-0.3:1. The technical result consists in increasing the efficiency of the process by preventing the formation of an intermediate layer in the extractor column, by reducing the ratio of solvent:extract, and, as a consequence, by increasing the productivity of the plant, simplifying the process of drying the solvent, and eliminating a paraffin-naphthene solvent, which substantially simplifies the regeneration of extractant from the raffinate solution.
1. A process for producing non-carcinogenic aromatic process oil containing less than 3.0% of a PCA extract according to method IP-346, the process comprising the steps of:
(a) refining a petroleum oil fraction with a solvent and extracting residual and distillate extracts from the refined fraction;
(b) mixing the residual and distillate extracts with a polar solvent comprising a mixture of dimethyl sulphoxide and N-methylpyrrolidone, wherein a weight ratio of dimethyl sulphoxide to N-methylpyrrolidone is in a range of 1:0.1-0.5;
(c) filtering a mixture of the extracts and the polar solvent formed in step (b) to provide (i) a light fraction comprising partially refined petroleum oil extracts and (ii) a heavy fraction comprising an extraction solution;
(d) treating the light fraction with the polar solvent to produce a raffinate; and
(e) regenerating the polar solvent with use of the heavy fraction.
2. The process according to claim 1 , wherein a weight ratio of the polar solvent to the light fraction in step (d) is within a range of 1.5-2.5:1.
3. The process according to claim 1 , wherein a weight ratio of the polar solvent to the residual and distillate extracts in step (b) is within a range of 0.1-0.3:1.