Alternative methanol to olefin (MTO) process

Abstract

A process and plant for producing an olefin stream, comprising passing a feedstock stream comprising oxygenates over a catalyst thereby forming an olefin stream; using a first reactor set including a single reactor or several reactors for the partial or full conversion of the oxygenates; and in series arrangement with the first reactor set, using a second reactor set including a single reactor or several reactors, for the further conversion of the oxygenates, and a phase separation stage in between the first reactor set and the second reactor set, for thereby forming the olefin stream.

Claims

1. A process for producing an olefin stream comprising passing a feedstock stream comprising oxygenates over a catalyst active in the conversion of oxygenates, thereby forming an olefin stream, said process comprising the steps of: passing the feedstock stream comprising oxygenates through a first reactor set including a single reactor or several reactors for the partial or full conversion of the oxygenates, and through a second reactor set including a single reactor or several reactors for the further conversion of the oxygenates and a phase separation stage in between the first reactor set and the second reactor set, for thereby forming the olefin stream, wherein the process comprises: passing the feedstock stream comprising oxygenates through the first reactor set under conditions for partly converting the oxygenates, thereby forming a raw olefin stream comprising unconverted oxygenates and C2-C8 olefins; and passing the raw olefin stream through said separation stage, for producing: a first olefin stream, which is rich in lower olefins; a separated oxygenate stream comprising the unconverted oxygenates; and a second olefin stream, which is rich in higher olefins; combining the first olefin stream with the separated oxygenate stream comprising the unconverted oxygenates, thereby forming a combined stream comprising lower olefins and the unconverted oxygenates; passing the resulting combined stream comprising lower olefins and unconverted oxygenates through the second reactor set under conditions for fully converting the unconverted oxygenates and the lower olefins, into a third olefin stream which is rich in higher olefins; combining the second olefin stream with the third olefin stream, thereby forming said olefin stream.

2. The process according to claim 1, wherein the several reactors in the first reactor set and/or second reactor set are mutually arranged in parallel.

3. (canceled)

4. The process according to claim 1, wherein the process comprises recycling to the first and/or second reactor set a portion of the olefin stream.

5. The process according to claim 1, wherein the first reactor set consists of 2-4 reactors, and the second reactor set consists of 1-3 reactors.

6. The process according to claim 1, wherein the catalyst comprises a zeolite having a structure selected from MFI, MEL, SZR, SVR, ITH, IMF, TUN, FER, EUO, MSE, *MRE, MWW, TON, MTT, AFO, AEL, and combinations thereof; and wherein the process is conducted at a pressure of 1-60 bar and a temperature of 125-700 C.

7. The process according to claim 6, wherein the process is conducted over a catalyst comprising a zeolite with a framework having a 10-ring pore structure, in which said 10-ring pore structure comprises (a) a unidimensional (1-D) pore structure; and at a pressure of 1-50 bar and temperature of 150-600 C.

8. The process according to claim 6, in which the zeolite has a 1-D pore structure and is any of *MRE (ZSM-48), MTT (ZSM-23), TON (ZSM-22), or combinations there-of; and optionally having a silica-to-alumina ratio (SAR) of up to 110; and the process is conducted at a pressure of 1-25 bar, and a temperature of 240-360 C.

9. The process according to claim 1, wherein the feedstock stream is combined with a diluent, the feedstock stream is methanol and it is diluted to a methanol concentration in the feedstock of 2-20 vol. %.

10. The process according to claim 1, wherein the feedstock comprising oxygenates is derived from one or more oxygenates taken from the group consisting of triglycerides, fatty acids, resin acids, ketones, aldehydes or alcohols or ethers, where said oxygenates originate from one or more of a biological source, a gasification process, a pyrolysis process, Fischer-Tropsch synthesis, or methanol-based synthesis.

11. The process according to claim 1, wherein the oxygenates are selected from methanol (MeOH); dimethyl ether (DME); or combinations thereof.

12. The process according to claim 1, further comprising: separating from the olefin stream an isoparaffin stream.

13. The process according to claim 1, further comprising: passing at least a portion of the olefin stream through an oligomerization step over an oligomerization catalyst, and optionally subsequently conducting a separation step, for thereby producing an oligomerized stream; and passing at least a portion of the oligomerized stream through a hydrogenation step over a hydrogenation catalyst, and optionally subsequently conducting a separation step, for thereby producing a hydrocarbon stream comprising hydrocarbons boiling in the jet fuel range.

14. The process according to claim 13, wherein the oligomerization step and hydrogenation step are combined in a single hydro-oligomerization step, wherein the oligomerization step is dimerization, optionally also trimerization, by the hydro-oligomerization step being conducted by reacting, under the presence of hydrogen, the olefin stream over a catalyst comprising a hydrogenation metal.

15. Plant for producing an olefin stream from a feedstock comprising oxygenates, said plant being an oxygenate conversion section comprising: a first reactor set including a single reactor or several reactors, for the partial or full conversion of the oxygenates; and in series arrangement with the first reactor set, a second reactor set including a single reactor or several reactors, for the further conversion of the oxygenates, and a phase separation section arranged in between the first reactor set and the second reactor set, for thereby forming the olefin stream, wherein the first reactor set includes a single reactor or several reactors, adapted for receiving said feedstock comprising oxygenates and for the partial or full conversion of the oxygenates, thereby forming a raw olefin stream comprising unconverted oxygenates and C2-C8 olefins; the phase separation section comprises a three-phase separator, arranged downstream the first reactor set, said phase separation section being adapted for receiving said raw olefin stream and forming: a first olefin stream, which is rich in lower olefins; a separated Page 7 oxygenate stream comprising the un-converted oxygenates; a second olefin stream, which is rich in higher olefins; a mixing device for combining the first olefin stream with the separated oxygenate stream comprising the unconverted oxygenates, thereby forming a combined stream comprising lower olefins, and the unconverted oxygenates; the second reactor set includes a single reactor or several reactors, and arranged downstream said phase separation section, adapted for receiving said combined stream, thereby forming a third olefin stream which is rich in higher olefins; and a mixing device for combining the second olefin stream with the third olefin stream, thereby forming said olefin stream.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0172] The sole FIGURE is a simplified FIGURE showing the conversion of oxygenates to olefins and optional further conversion to jet fuel in accordance with an embodiment of the invention.

DETAILED DESCRIPTION

[0173] With reference to the FIGURE, an oxygenate conversion section 200, such as MTO section, is shown and optionally (stippled lines) an oligomerization and hydrogenation section 300 for further conversion into jet fuel. A feedstock stream 100 comprising oxygenates such as methanol and/or DME passes through a first reactor set 200, for instance 3 reactors arranged in parallel, for thereby achieving 50-70% conversion of the methanol and producing a raw olefin stream 105 comprising water, methanol and olefins e.g. C2-C8 olefins. The raw olefin stream 105 is subjected to separation in a 3-phase separator 200 thereby producing a first olefin stream 105a, which is rich in lower olefins, particularly C2-C3 olefins or mainly C2-olefins (ethylene), a separated oxygenate stream 105b comprising the unconverted oxygenates (unconverted methanol), and a second olefin stream 105c which is rich in higher olefins, particularly C3-C8 olefins incl. C4-C8 olefins. The first olefin stream 105a is combined with the separated oxygenate stream 105b comprising the unconverted oxygenates, thereby forming a combined stream 105d comprising lower olefins, particularly C2-C3 olefins or mainly ethylene, and the unconverted oxygenates. This combined stream is pressurized and fed to a second reactor set 200 arranged downstream, and which may for instance include two reactors arranged in parallel, for thereby achieving full conversion e.g. 85% or 90% or higher. The first reactor set 200 and second reactor set 200 are thereby arranged in series. A third olefin stream 105e is produced which is rich in higher olefins, particularly C3-C8 olefins incl. C4-C8 olefins. Finally, the second olefin stream 105c (bypass stream) is combined with the third olefin stream 105e, thereby forming said olefin stream 106 which may have been pressurized. By the above arrangement of the MTO section 200, the rectors of the first and second set can be operated at low temperature, e.g. 250-350 C. or 260-360 C., which improves the life-time conversion capacity of the catalysts used and also improve the selectivity to higher olefins due to less cracking. The resulting olefin stream 106, suitably after removing its water content, is optionally further converted (as shown by the stippled lines) in a downstream oligomerization and hydrogenation section 300, which is combined as a single hydro-oligomerization step, for instance in a single reactor, thereby producing a hydrocarbon stream 112 comprising hydrocarbons boiling in the jet fuel range (C8-C16), particularly SAF.