Recovery of aliphatic hydrocarbons

A process for the recovery of aliphatic hydrocarbons from a liquid hydrocarbon feedstock stream comprising aliphatic hydrocarbons, heteroatom containing organic compounds and optionally aromatic hydrocarbons, wherein the liquid hydrocarbon feedstock stream comprises at least part of a hydrocarbon product formed in a process comprising cracking of waste plastics, said process comprising the steps of:

• a) contacting at least part of the liquid hydrocarbon feedstock stream with an extraction solvent a) which contains one or more heteroatoms, and subjecting the liquid hydrocarbon feedstock stream to liquid-liquid extraction with the extraction solvent a), resulting in a first stream comprising aliphatic hydrocarbons and a second stream comprising extraction solvent a), aliphatic hydrocarbons, heteroatom containing organic compounds and optionally aromatic hydrocarbons;
• b1) mixing at least part of the second stream resulting from step a) with a demixing solvent b) which contains one or more heteroatoms and has a miscibility in heptane which is lower than the miscibility of extraction solvent a) in heptane, and separating the resulting mixture into a first stream comprising aliphatic hydrocarbons and optionally aromatic hydrocarbons and a second stream comprising extraction solvent a), demixing solvent b), heteroatom containing organic compounds and optionally aromatic hydrocarbons;
• b2) mixing at least part of the second stream resulting from step b1) with demixing solvent b) and separating the resulting mixture into a first stream comprising heteroatom containing organic compounds and optionally aromatic hydrocarbons and a second stream comprising extraction solvent a) and demixing solvent b);
• wherein steps b1) and b2) are sub-steps of a step b) which comprises two or more sub-steps;
• c) separating at least part of the second stream resulting from step b2) into a first stream comprising demixing solvent b) and a second stream comprising extraction solvent a);
• d) recycling at least part of the extraction solvent a) from the second stream resulting from step c) to step a);
• and
• e) optionally recycling at least part of the demixing solvent b) from the first stream resulting from step c) to one or more of the sub-steps of step b),
• wherein:
• (i) before step a), heteroatom containing organic compounds are removed from the liquid hydrocarbon feedstock stream by contacting at least part of that stream with a washing solvent d) which contains one or more heteroatoms and has a miscibility in heptane which is lower than the miscibility of extraction solvent a) in heptane.