Electrically heated carbon monooxide reactor
A reactor system and a process for carrying out reverse water gas shift reaction of a feedstock comprising CO 2 and H 2 to a first product gas comprising CO are provided, where a methanation reaction take place in parallel to the reverse water gas shift reaction, and where the heat for the endothermic reverse water gas shift reaction is provided by resistance heating.
1. A reactor system for carrying out a reverse water gas shift reaction for production of a first product gas comprising CO from a feedstock comprising CO 2 and H 2 , said reactor system comprising:
a supply of feedstock comprising CO 2 and H 2 ;
a structured catalyst comprising a macroscopic structure of an electrically conductive material and a catalytically active material capable of catalysing both the reverse water gas shift reaction and a methanation reaction;
the structured catalyst arranged for being operated under such temperature and pressure that both the reverse water gas reaction and the methanation reaction take place;
a pressure shell housing said structured catalyst, said pressure shell comprising an inlet for letting in said feedstock and an outlet for letting out product gas, wherein said inlet is positioned so that said feedstock enters said structured catalyst in a first end of said structured catalyst and said product gas exits said structured catalyst from a second end of said structured catalyst;
a heat insulation layer between said structured catalyst and said pressure shell;
at least two conductors electrically connected to said structured catalyst and to an electrical power supply placed outside said pressure shell, wherein said electrical power supply is dimensioned to heat at least part of said structured catalyst to a temperature of at least 500° C. by passing an electrical current through said macroscopic structure, wherein said at least two conductors are connected to the structured catalyst at a position on the structured catalyst closer to said first end of said structured catalyst than to said second end of said structured catalyst, and wherein the structured catalyst is constructed to direct an electrical current to run from one conductor substantially to the second end of the structured catalyst and return to a second end of said at least two conductors;
an outlet for a first product gas comprising CO.
2. The reactor system according to claim 1 , wherein said macroscopic structure supports a ceramic coating.
3. The reactor system according to claim 2 , wherein said ceramic coating at least partly supports a catalytically active material.
4. The reactor system according to claim 2 , wherein the ceramic coating supports a catalytically active material in the most downstream part of the structured catalyst.
5. The reactor system according to claim 4 , wherein the most downstream part of the structured catalyst ranges from 10% to 100% of an extension along a length of the structured catalyst from the first end to the second end.
6. The reactor system according to claim 1 , wherein the structured catalyst has a first reaction zone disposed closest to the first end of said structured catalyst, wherein the first reaction zone has an overall exothermic reaction, and a second reaction zone disposed closest to the second end of said structured catalyst, wherein the second reaction zone has an overall endothermic reaction.
7. The reactor system according to claim 6 , wherein the first reaction zone has an extension of from 5% to 60% of the length of the structured catalyst from its first to its second end.
8. The reactor system of claim 1 , wherein the concentration of methane is higher in the partly catalyzed feedstock inside at least a part of the structured catalyst than in the feedstock and in the first product gas.
9. The reactor system according to claim 1 , wherein the temperature of the structured catalyst is continuously increasing from the first end to the second end of the structured catalyst.
10. The reactor system according to claim 1 , wherein said electrical power supply is dimensioned to heat at least part of said structured catalyst to a temperature of at least 600° C.
11. A method for rapidly switching a reverse water gas shift reaction of a feedstock comprising CO 2 in a reactor system according to claim 1 , from a first steady-state reaction condition (A) to a second steady-state reaction condition (B) or vice-versa; said method comprising the steps of:
in said first steady-state reaction condition (A):
supplying said feedstock to the reactor system in a first total flow, and
supplying a first electrical power via electrical conductors connecting an electrical power supply placed outside said pressure shell to said structured catalyst, thereby allowing a first electrical current to run through said electrically conductive material,
thereby heating at least part of the structured catalyst to a first temperature at which said feedstock is converted to a first product gas over said structured catalyst under said first steady-state reaction conditions (A); and said first product gas is outlet from the reactor system;
and, in said second steady-state reaction condition (B):
supplying said feedstock to the reactor system in a second total flow,
supplying a second electrical power via electrical conductors connecting an electrical power supply placed outside said pressure shell to said structured catalyst, thereby allowing a second electrical current to run through said electrically conductive material,
thereby heating at least part of the structured catalyst to a second temperature; at which said feedstock is converted to a second product gas over said structured catalyst under said second steady-state reaction conditions (B); and said second product gas is outlet from the reactor system;
wherein said second electrical power is higher than said first electrical power; and/or said second total flow is higher than said first total flow.
12. The method according to claim 11 , wherein the ratio of total gas feed flow in said first reaction condition A to said second reaction condition B (A:B) is at least 1:10.
13. A process for converting a feedstock comprising CO 2 and H 2 to a first product gas comprising CO in a reactor system comprising a pressure shell housing a structured catalyst comprising a macroscopic structure of electrically conductive material and a catalytically active material; wherein said reactor system is provided with heat insulation between said structured catalyst and said pressure shell; said process comprising the steps of:
providing a pressurized feedstock;
supplying said pressurized feedstock to said pressure shell through an inlet positioned so that said feedstock enters said structured catalyst in a first end of said structured catalyst;
using a catalytically active material capable of catalysing both the reverse water gas shift reaction and a methanation reaction;
allowing the feedstock to undergo a reverse water gas shift reaction over the structured catalyst under such temperature and pressure that both the reverse gas shift reaction and the methanation reaction take place;
outletting a product gas from said pressure shell, wherein said product gas exits said structured catalyst from a second end of said structured catalyst;
supplying electrical power via electrical conductors connecting an electrical power supply placed outside said pressure shell to said structured catalyst, allowing an electrical current to run through said macroscopic structure, thereby heating at least part of the structured catalyst to a temperature of at least 500° C., wherein said at least two conductors are connected to the structured catalyst at a position on the structured catalyst closer to said first end of said structured catalyst than to said second end of said structured catalyst, and wherein the structured catalyst is constructed to direct an electrical current to run from one conductor substantially to the second end of the structured catalyst and return to a second of said at least two conductors, thereby heating at least part of the structured catalyst to a temperature sufficient for said feedstock to undergo the reverse water gas shift reaction over the structured catalyst,
outletting a first product gas comprising CO from the reactor system.
14. The process according to claim 13 , wherein the structured catalyst has a first reaction zone disposed closest to the first end of said structured catalyst, wherein the first reaction zone has an overall exothermic reaction, and a second reaction zone disposed closest to the second end of said structured catalyst, wherein the second reaction zone has an overall endothermic reaction.
15. The process according to claim 14 , wherein the first reaction zone has an extension of 5 to 60% of the length of the structured catalyst from its first to its second end.
16. The process according to claim 13 , wherein the concentration of methane is higher in the partly catalyzed feedstock inside at least a part of the structured catalyst than in the feedstock and in the first product gas.
17. The process according to claim 13 , wherein the temperature is continuously increasing from the first end to the second end of the structured catalyst.
18. The process according to claim 13 , wherein said electrical power supply is dimensioned to heat at least part of said structured catalyst to a temperature of at least 500° C.
19. The process according to claim 13 , wherein the pressure of the structured catalyst is between 2 and 30 bar.
20. The process according to claim 13 , wherein the process further comprises the step of feeding the first product gas comprising synthesis gas to an upgrading unit and separating it into an upgraded synthesis gas stream and one or more off-gas stream.