Processes and Systems for In-Line HBR Oxidation and Cyclic Oxygen Shuttle
An embodiment relates to a process for converting lower molecular weight, gaseous alkanes to higher hydrocarbons, such as olefins, higher molecular weight hydrocarbons, or mixtures thereof, that may use in-line hydrogen bromide oxidation for capture of hydrogen bromide produced in the process. An embodiment may provide a process for producing elemental halogen comprising: providing a first stream comprising a hydrogen halide; contacting the first stream with a metal oxide to form water, elemental halogen, and at least some metal halide, wherein the metal oxide comprises a metal capable of forming a plurality of stable oxidation states; and contacting the metal halide with an oxygen source to produce a regenerated metal oxide, wherein the oxygen source contacts the metal halide under conditions sufficient to avoid release of elemental halogen.
1 . A process for producing elemental halogen comprising:
providing a first stream comprising a hydrogen halide;
contacting the first stream with a metal oxide to form water, elemental halogen, and at least some metal halide, wherein the metal oxide comprises a metal capable of forming a plurality of stable oxidation states; and
contacting the metal halide with an oxygen source to produce a regenerated metal oxide, wherein the oxygen source contacts the metal halide under conditions sufficient to avoid release of elemental halogen.
2 . The process of claim 1 , wherein the elemental halogen is bromine, and wherein the first stream further comprises methane.
3 . The process of claim 1 , wherein the metal of the metal oxide comprises at least one metal selected from the group consisting of chromium, iron, copper, tin, and vanadium.
4 . The process of claim 1 , further comprising contacting the water with a stripping gas to recover a fraction of the elemental halogen from the water.
5 . The process of claim 4 , wherein the stripping gas comprises oxygen, and the stripping gas with the recovered elemental halogen is the oxygen source.
6 . The process of claim 1 , wherein metal of the metal oxide comprises copper, and wherein the step of contacting the metal halide occurs at a temperature from about 25° C. to about 150° C., and wherein the step of contacting the first stream occurs at a temperature of about 150° C. to about 350° C.
7 . A process for producing higher hydrocarbons comprising:
providing a first stream comprising lower molecular weight alkanes and a hydrogen halide;
contacting the first stream with a metal oxide to form oxidation products comprising water, elemental halogen, and a metal halide;
reacting at least a portion the methane and at least a portion of the elemental halogen to form halogenation products comprising alky halides and a first portion of produced hydrogen halide; and
contacting at least a portion of the alkyl halides with a catalyst to produce synthesis products comprising higher hydrocarbons and a second portion of produced hydrogen halide.
8 . The process of claim 7 wherein the metal oxide comprises a metal capable of forming a plurality of stable oxidation states.
9 . The process of claim 7 wherein the metal of the metal oxide comprises at least one metal selected from the group consisting of chromium, iron, copper, tin, and vanadium.
10 . The process of claim 7 wherein the elemental halogen comprises bromine.
11 . The process of claim 7 further comprising contacting the water with a stripping gas to recover a fraction of the elemental halogen from the water.
12 . The process of claim 7 further comprising contacting the metal halide with an oxygen source to regenerate at least a portion of the produce a regenerated metal oxide.
13 . The process of claim 7 wherein the catalyst comprises a zeolite catalyst.
14 . The process of claim 7 further comprising combining the synthesis products with a feed gas comprising a lower molecular weight alkane and separating the combined stream into a C 1 recycle stream comprising methane and the produced alkyl halide, a C 2- C 3 recycle stream comprising ethane and propane, and a liquid products stream comprising C 4+ hydrocarbons.
15 . The process of claim 14 , wherein the methane in the C 1 recycle stream and the C 2- C 3 recycle stream are separately brominated.
16 . The process of claim 7 , wherein lower molecular weight alkanes comprise methane from a feed gas.
17 . The process of claim 16 , wherein the feed gas comprises natural gas.
18 . The process of claim 7 , wherein metal of the metal oxide comprises copper, and wherein the step of contacting the first stream occurs at a temperature of about 150° C. to about 350° C., and wherein the process further comprises contacting the metal halide with an oxygen source at a temperature from about 25° C. to about 150° C.
19 . A system for producing higher hydrocarbons comprising:
an oxidation unit comprising a metal oxide reactor bed for converting a hydrogen halide to a metal halide and elemental halogen, wherein at least a portion of the metal oxide in the metal oxide reactor bed is converted to a metal halide, and wherein the oxidation unit further comprises an offline metal oxide bed containing converted metal halide in fluid communication with an oxygen source;
a bromination unit in fluid communication with the oxidation unit for reacting an alkane with the elemental halogen; and
a synthesis unit in fluid communication with the bromination unit, wherein the synthesis unit comprises a catalyst for converting alkyl halides to higher hydrocarbons.
20 . The system of claim 19 , further comprising a separation unit in fluid communication with the synthesis unit and the oxidation unit, wherein the separation unit is configured to receive a synthesis product stream from the synthesis unit and supply a C 1 recycle stream to the oxidation unit.