Upgrading streams comprising C
A first stream containing 1,3-butadiene, C 4 acetylenes, and optionally C 3 hydrocarbons, is mixed with a portion of the liquid recycle stream from a C 4 acetylene hydrogenation reactor containing hydrogenated C 4 acetylenes and a molecular hydrogen-containing stream, the resulting mixed stream is then fed to a C 4 acetylene hydrogenation reactor to selectively hydrogenate the C 4 acetylenes in the crude butadiene stream without appreciable 1,3-butadiene conversion.
1. A selective hydrogenation process, comprising:
providing a first stream comprising hydrocarbon compounds, wherein the first stream comprises:
at least 20 wt. % of C3 hydrocarbons; and
C 4 hydrocarbons comprising C 4 acetylenes and 1,3-butadiene;
contacting the first stream with a recycle portion of a liquid stream containing hydrogenated C 4 acetylenes and with a molecular hydrogen-containing stream to form a mixed feed stream, wherein the mixed feed stream comprises:
(i) one or more the C 3 hydrocarbon compounds, and
(ii) C 4 hydrocarbon compounds including the C 4 acetylenes and the 1,3-butadiene;
sending the mixed feed stream to a hydrogenation reactor to hydrogenate at least a portion of the C 4 acetylenes to form an effluent stream containing hydrogenated C 4 acetylenes;
separating the liquid stream containing hydrogenated C 4 acetylenes from the effluent stream; and
removing from the liquid stream the recycle portion of the liquid stream containing hydrogenated C 4 acetylenes.
2. The selective hydrogenation process of claim 1 , wherein the mixed feed stream comprises propylene.
3. The selective hydrogenation process of claim 1 , wherein the hydrogenation of at least a portion of the C 4 acetylenes is conducted at a pressure great enough to keep the hydrocarbons in liquid phase.
4. The selective hydrogenation process of claim 3 , wherein the pressure ranges from about 320 psia (about 2.2 MPa) to about 565 psia (about 3.9 MPa).
5. The selective hydrogenation process of claim 1 , wherein the hydrogenation reactor has an inlet, and where the temperature at the inlet ranges from about 80° F. (27° C.) to about 122° F. (about 50° C.).
6. The selective hydrogenation process of claim 1 , wherein the hydrogenation converts:
(1) at least 45 wt % of the C 4 acetylenes of the first stream; and
(2) at least one of:
(a) at least 10 wt % of the 1,3-butadiene of the first stream,
(b) less than or equal to 10 wt % of the C 3 hydrocarbon of the first stream, or
(c) a combination of (a) and (b).
7. The selective hydrogenation process of claim 1 , wherein a recycle ratio of weight of the recycled portion of the liquid stream to weight of the first stream ranges from about 0.75 to about 1.5.