Catalytic reactors

1. A compact catalytic reactor comprising a multiplicity of first and second flow channels arranged alternately in said reactor, for carrying first and second fluids, respectively, wherein at least said first fluids undergo a chemical reaction; each first flow channel containing a removable gas-permeable catalyst structure incorporating a metal foil substrate, said catalyst structure defining flow paths therethrough; wherein said substrate comprises corrugated foil; wherein said catalyst structure incorporates a multiplicity of resilient strips which are bent out from the foil substrate peaks so as to project from the substrate peaks and to support said catalyst structure resiliently spaced away from at least one adjacent wall of said channel, each strip being connected to said catalyst structure only at an end of said strip, and being integral with said foil; and wherein said catalyst structure, excluding said projecting strips, is of height less than a corresponding height of said channel by between 0.1 mm and about 1 mm.

2. A catalytic reactor as claimed in claim 1 wherein chemical reactions occur in both said first and said second flow channels, and wherein second flow channels contain removable gas-permeable catalyst structures that incorporate a metal foil substrate, and which define flow paths therethrough, wherein said catalyst structure incorporates a multiplicity of projecting resilient strips which support said catalyst structure spaced away from at least one adjacent wall of said channel, each strip being connected to said catalyst structure only at ends of said strip, and being integral with said foil.

3. A catalytic reactor as claimed in claim 1 wherein said catalyst structure comprises resilient strips projecting in opposite directions, so that said catalyst structure is spaced away from both opposed adjacent walls of said channel.

4. A catalytic reactor as claimed in claim 1 wherein said catalyst structure comprises said metal foil corrugated into castellations, and said resilient strips project from peaks of said castellations.

5. A catalytic reactor as claimed in claim 4 wherein said resilient strips comprise projecting lugs, attached to said foil at one end.

6. A catalytic reactor as claimed in claim 1 wherein said first fluids undergo steam reforming.

7. A catalytic reactor as claimed in claim 1 wherein said first fluids undergo Fischer-Tropsch synthesis.

8. A plant for processing natural gas for obtaining longer chain hydrocarbons, said plant comprising

a first reactor as defined by claim 1 , wherein said first fluids undergo steam reforming, for reacting methane with steam for forming synthesis gas, and

a second reactor as defined by claim 1 ,

wherein the second reactor is configured to be fed a stream from the first reactor;

wherein said first fluids undergo Fischer-Tropsch synthesis for generating longer-chain hydrocarbons;

wherein the first reactor is a reforming reactor; and

wherein the second reactor is a synthesis reactor.

9. A compact catalytic reactor as claimed in claim 1 wherein said substrate comprises a corrugated foil, and the corrugations are rectangular.

10. A compact catalytic reactor comprising a multiplicity of first and second flow channels arranged alternately in the reactor, for carrying first and second fluids, respectively, wherein at least said first fluids undergo a chemical reaction; each first flow channel containing a removable gas-permeable catalyst structure incorporating a metal foil substrate, said catalyst structure defining flow paths therethrough; wherein said substrate comprises corrugated foil; wherein said catalyst structure incorporates a multiplicity of resilient strips which are bent out from the foil substrate peaks so as to project from the substrate peaks and to support said catalyst structure resiliently spaced away from at least one adjacent wall of said channel, each strip being connected to the catalyst structure only at an end of the strip, and being integral with a said foil.

11. A compact catalytic reactor as claimed in claim 10 wherein said substrate comprises a corrugated foil, and the corrugations are rectangular.