Method for starting up a DME synthesis reactor

Patent metadata

Field	Value
Publication number	US-9376360-B2
Application number	US-201314407517-A
Country	US
Kind code	B2
Filing date	Jun 3, 2013
Priority date	Jun 15, 2012
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

A method for starting up a DME synthesis reactor in which methanol is converted by dehydration to dimethyl ether on a solid catalyst, wherein the catalyst is heated up with condensing methanol vapor, possibly in several steps. In a final treatment step with superheated methanol vapor, the catalyst is dried and its temperature is raised to the starting temperature of the methanol dehydration.

First claim

The invention claimed is:

1. A method for heating up a catalytic fixed-bed reactor configured to convert methanol to dimethyl ether (DME), the method comprising:
(a) adjusting a catalytic fixed-bed reactor, comprising a solid catalyst suitable for dehydrating methanol to DME, to an initial temperature of the solid catalyst at a first pressure, at least one temperature measuring device being mounted in the presence of the catalyst;
(b) evaporating liquid pure methanol in an evaporation device, to obtain a first vaporous pure methanol stream;
(c) contacting the first vaporous pure methanol stream with the catalyst, until a condensation temperature of the methanol is reached at the first pressure, to obtain a liquid condensate comprising methanol;
(d) providing the liquid condensate to a separating device, the separating device being in fluid connection with the catalyst, and discharging a condensate stream comprising methanol from the separating device;
(e) lowering the pressure in the catalytic fixed-bed reactor to a second pressure, the second pressure being below the first pressure, and contacting the catalyst with a second vaporous pure methanol stream suitable for removing condensed methanol, wherein the second vaporous pure methanol stream is superheated with respect to the second pressure;
(f) heating up the second vaporous pure methanol stream using a heating device, to obtain a vaporous, superheated pure methanol stream, and contacting the vaporous, superheated pure methanol stream with the catalyst, wherein the vaporous, superheated pure methanol stream is heated up to such an extent that in or at the catalyst a fixed end temperature is reached.

2. The method of claim 1 , wherein (b) to (d) are repeated several times, and
wherein the first pressure is increased incrementally.

3. The method of claim 1 , wherein the fixed end temperature corresponds to a light-off temperature or starting temperature of dehydrating methanol to DME at the fixed reactor pressure.

4. The method of claim 1 , wherein the solid catalyst is in the form of a bed of granular catalyst.

5. The method of claim 1 , wherein the solid catalyst comprises alumina.

6. The method of claim 1 , further comprising:
recycling condensed methanol from the separating device to the evaporation device.

7. The method of claim 1 , wherein the separating device is integrated into the fixed-bed reactor.

8. A method of producing dimethyl ether (DME) by heterogeneously catalyzed dehydration of a gaseous or vaporous feed stream containing methanol on a solid catalyst active for dehydrating methanol to DME, comprising:
(a) first, heating up a catalytic fixed-bed reactor by the method of claim 1 ;
(b) catalytically converting a feed stream comprising gaseous methanol under dehydration conditions to obtain a product stream comprising DME; and
(c) recovering the DME from the product stream comprising the DME.

9. A plant configured to heat up a catalytic fixed-bed reactor configured to convert methanol to dimethyl ether (DME), the plant comprising:
(a) a fixed-bed reactor comprising a solid methanol dehydration catalyst, a first pressure maintaining device, and a temperature measuring device;
(b) a methanol evaporation device comprising a second pressure maintaining device;
(c) a separating device configured to separate liquid condensate comprising methanol, the separating device being in direct fluid connection with the solid methanol dehydration catalyst; and
(d) a return conduit configured to recirculate liquid condensate comprising methanol from the separating device to the methanol evaporation device, the return conduit being in fluid connection with the separating device and the methanol evaporation device.

10. The plant of claim 9 , wherein the separating device is integrated into the fixed-bed reactor.

11. The method of claim 1 , wherein the at least one temperature measuring device is mounted in the same space as the catalyst.

12. The method of claim 1 , wherein the at least one temperature measuring device is mounted in the catalyst.

13. The method of claim 1 , wherein the solid catalyst is present as a catalyst honeycomb.

14. The method of claim 1 , wherein the separating device is arranged outside the fixed-bed reactor.

15. The plant of claim 9 , wherein the separating device is arranged outside the fixed-bed reactor.

16. The plant of claim 9 , wherein the fixed-bed reactor comprises more than one temperature measuring device.

17. The plant of claim 9 , wherein the solid methanol dehydration catalyst is in the form of a bed of granular catalyst.

18. The plant of claim 9 , wherein the solid methanol dehydration catalyst comprises alumina.

19. The plant of claim 9 , wherein the at least one temperature measuring device is mounted in the solid methanol dehydration catalyst.

20. The plant of claim 9 , wherein the solid methanol dehydration catalyst is present as a catalyst honeycomb.

21. A plant configured to heat up a catalytic fixed-bed reactor configured to convert methanol to dimethyl ether (DME), the plant comprising:
(a) a fixed-bed reactor comprising a solid methanol dehydration catalyst, a first pressure maintaining device, and a temperature measuring device;
(b) a methanol evaporation device comprising a second pressure maintaining device;
(c) a separating device configured to separate liquid condensate comprising methanol, the separating device being in fluid connection with the solid methanol dehydration catalyst; and
(d) a return conduit configured to recirculate liquid condensate comprising methanol from the separating device to the methanol evaporation device, the return conduit being in fluid connection with the separating device and the methanol evaporation device,
wherein the separating device is integrated into the fixed-bed reactor.

Assignees

• Air Liquide
• L Air Liquide Société Anonyme Pour L Étude Et L Expl Des Procedes Georges Claude

Inventors

• Ahlers Bernd
• Mitschke Peter
• Herzog Joerg

Classifications

• B01J35/56

  Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional [3D] monoliths · CPC title

• B01J35/30

  characterised by their physical properties · CPC title

• C07C41/09 Primary

  by dehydration of compounds containing hydroxy groups · CPC title

• C07C43/043

  Dimethyl ether · CPC title

• B01J8/0285

  Heating or cooling the reactor (for tubular reactors in furnaces B01J8/062) · CPC title