Method of producing a fuel additive with a hydration unit

A method of producing a fuel additive, comprising:

• passing a raffinate stream comprising C4 hydrocarbons through a hydrogenation unit, forming a first process stream, wherein greater than or equal to 90% by weight of any butadiene present in the raffinate stream is converted to 1-butene and/or 2-butene within the hydrogenation unit, the hydrogenation unit comprising a first reactor stage, a second reactor stage and a third reactor stage in series;
• passing the first process stream comprising 1-butene and/or 2-butene and a solvent comprising at least one of N-methylpyrrolidone, formylpyrrolidine, N-Formylmorpholine, or butyrolactone through an extractive distillation unit, producing a C4 olefin stream and a C4 paraffin stream;
• passing the C4 olefin stream comprising the solvent through a stripper column, producing a purified C4 olefin stream, wherein at least a portion of the solvent is removed from the C4 olefin stream in the stripper column;
• passing the purified C4 olefin stream through a hydration unit, wherein the purified C4 olefin stream is exposed to an acid catalyst comprising at least one of phosphoric acid, a cation exchange resin, sulphonated polystyrene, hypophosphorous acid, polymer, niobium oxide, or a zeolite, and wherein greater than or equal to 80% by weight of any butene present in the purified C4 olefin stream is converted to butanol within the hydration unit, and wherein the purified C4 olefin stream comprises less than 1.0% butadiene by weight prior to passing through the hydration unit, and wherein the purified C4 olefin stream comprises less than 1.0% by weight n-butane and iso-butane prior to passing through the hydration unit;
• and
• withdrawing a C4 alcohol fuel additive product from the hydration unit, wherein the fuel additive product comprises 5% to 50% by weight trimethyl-pentane;
• and
• wherein the fuel additive product further comprises at least one of 1-butanol, 2-butanol, tert-butyl alcohol, di-isobutene, other C4 dimers, di-isobutyl ether, or di-sec-butyl ether;
• wherein an octane number of the fuel additive product is greater than or equal to 87 RON or 80 MON, and a Reid vapor pressure of the fuel additive product is less than or equal to 55 kiloPascals;
• and
• further comprising withdrawing the C4 paraffin stream from the extractive distillation unit, wherein the C4 paraffin stream comprises n-butane and iso-butane, and subjecting the C4 paraffin stream to:
• (i) a de-isobutanizer column to separate n-butane from iso-butane, (ii) an isomerization unit, (iii) a dehydrogenation unit, and (iv) a methyl tertiary butyl ether synthesis unit to produce methyl tertiary butyl ether;
• and
• further comprising withdrawing a recycle stream from the extractive distillation unit and recycling the recycle stream to the raffinate stream or to a steam cracker unit.