Electrochemical process for olefin recovery using transition metal dithiolene complexes
AssigneeExxon Research & Engineering Co.
InventorsKun Wang, Edward Ira Stiefel
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Abstract
A novel scheme for olefin recovery/separation based on the redox properties of metal dithiolene complexes is described. The complex, [1,2-bis(cyano)ethylene-1,2-dithiolato]nickel, [Ni(S2C2(CN)2)2], when generated electrochemically, binds olefin to form an adduct. The olefin is released when the olefin adduct is reduced electrochemically. The reduced form of the metal dithiolene complex can then be re-oxidized to complete the cycle. For olefins such as 1-hexene, propylene, and ethylene, fast olefin binding and release is observed when modulated electrochemically. Olefin binding/release rates are fast as compared to the electrochemistry experiment (second or sub-second time-scale).
Claims11
An electrochemical method for separating olefins from olefin-containing streams, comprising:
- in an electrochemical cell contacting an olefin containing stream with a metal dithiolene compound selected from compounds represented by the formulas Ax{M[S2C2(RaRb)]2} or Ax{M[S2C6(R1R2R3R4)]2} at an electric potential sufficient to generate an oxidized form that binds the olefin to form an adduct of the olefin with the metal dithiolene compound and reducing the adduct at a lower electric potential sufficient to release the olefin, wherein A is a cation selected from Group IA, IB or onium ions, and X is 0, 1 or 2. M is a transition metal, Ra and Rb and R1, R2, R3, and R4 are independently selected and may be the same or different and are selected from hydrogen, electron withdrawing groups selected from halo-, heterocyclo-, cyano-, carboxylate, carboxylic ester, keto, nitro or sulfonyl groups, or trifluoromethyl or substituted or unsubstituted hydrocarbyl groups.
Dependencies are inferred from the claim text.