Abstract: A compact catalytic reactor (20) comprises a channel for a rapid reaction having an inlet (26) for a gas mixture to undergo the reaction. The channel is provided with two different catalyst structures (32, 34), a first catalyst structure (32) in the vicinity of the inlet (26) and a second catalyst structure (34) further from the inlet, such that a gas mixture supplied to the inlet flows past them both. The first catalyst structure (32) has little catalytic activity for the rapid reaction, whereas the second catalyst structure (34) has catalytic activity for the rapid reaction. This is applicable to combustion of gas mixtures containing hydrogen, for which the first catalyst structure (32) may comprise uncoated oxidised aluminium-containing ferritic steel, while the second catalyst structure (34) may incorporate Pt and/or Pd in an alumina support. Exhaust gases may also be recycled to the inlet (26) to inhibit combustion.

Abstract: A metal substrate is coated with a layer of ceramic, by spraying droplets of a slurry of a ceramic precursor onto the substrate, the substrate being at a temperature between 500° C. and 750° C. The ceramic comprises alumina, and is made macroporous by spraying a mixture of alumina sol and alumina particles with no more than 35% by weight of dispersible alumina. Spraying onto a red-hot surface in this fashion leads to a very marked improvement in adhesion of the resulting ceramic to the metal substrate. A catalytically active material may then be incorporated in the ceramic layer, so as to form a catalyst structure (16).

Abstract: A catalytic reactor (40) comprises a plurality of sheets (42) defining flow channels (44) between them. Within each flow channel (44) is a foil (46) of corrugated material whose surfaces are coated with catalytic material apart from where they contact the sheets (44). At each end of the reactor (40) are headers to supply gas mixtures to the flow channels (44), the headers communicating with adjacent channels being separate. The reactor (40) enables different gas mixtures to be supplied to adjacent channels (44), which may be at different pressures, and the corresponding chemical reactions are also different. Where one of the reactions is endothermic while the other reaction is exothermic, heat is transferred through the sheets (42) separating the adjacent channels (44), from the exothermic reaction to the endothermic reaction.

Abstract: Fischer-Tropsch synthesis is performed using a compact catalytic reactor unit (10) defining channels in which is a gas-permeable catalyst structure (16), the channels extending between headers (18). The synthesis occurs in at least two stages, as the reactor unit provides at least two successive channels (14, 14a) for the Fischer-Tropsch synthesis connected by a header, the gas flow velocity through the first channel being sufficiently high that no more than 65% of the carbon monoxide undergoes conversion. The gases are cooled (25) in the header between the two stages, so as to condense water vapour, and then pass through the second channel at a sufficiently high gas flow velocity that no more than 65% of the remaining carbon monoxide undergoes conversion. This lowers the partial pressure of water vapour and so suppresses oxidation of the catalyst.

Abstract: Methane is reacted with steam, to generate carbon monoxide and hydrogen in a first catalytic reactor (14); the resulting gas mixture can then be used to perform Fisher-Tropsch synthesis in a second catalytic reactor (26). In performing the steam/methane reforming, the gas mixture is passed through a narrow channel in which the mean temperature and exit temperature are both in the range 750° C. to 900° C., the residence time being less than 0.5 second, and the channel containing a catalyst, so that only those reactions that have comparatively rapid kinetics will occur. The heat is provided by combustion of methane in adjacent channels (17). The ratio of steam to methane should preferably be 1.4 to 1.6, for example about 1.5. Almost all the methane will undergo the reforming reaction, almost entirely forming carbon monoxide. After performing Fischer-Tropsch synthesis, the remaining hydrogen is preferably fed back (34) to the combustion channels (17).

Abstract: Methane is reacted with steam, to generate carbon monoxide and hydrogen in a first catalytic reactor, the resulting gas mixture can then be used to perform Fisher-Tropsch synthesis in a second catalytic reactor. In performing the steam/methane reforming, the gas mixture is passed through a narrow flow channel containing a catalyst structure on a metal substrate, and adjacent to a source of heat, in a time less than 0.5 s, so that only those reactions that have comparatively rapid kinetics will occur. Both the average temperature and the exit temperature of the channel are in the range 750° to 900° C. The ratio of steam to methane should preferably be 1.4 to 1.6, for example about 1.5. Almost all the methane will undergo the reforming reaction, almost entirely forming carbon monoxide. After performing Fischer-Tropsch synthesis, the remaining hydrogen is preferably used to provide heat for the reforming reaction.

Abstract: A catalytic reactor (20) comprises a plurality of sheets (21) defining flow channels (22) between them. Within each flow channel (22) is a foil (24) of corrugated material whose surfaces are coated with catalytic material. Flow channels (22, 22a) for a first gas extend in oblique directions relative to the flow channels (22b) for a second gas. The reactor (20) incorporates header chambers (26, 28) to supply gas mixtures to the flow channels (22), the headers communicating with adjacent channels being separate. The reactor (20) enables different gas mixtures to be supplied to adjacent channels (22), which may be at different pressures, and the corresponding chemical reactions are also different. Where one of the reactions is endothermic while the other reaction is exothermic, heat is transferred through the sheets (21) separating the endothermic reaction. When the catalyst is one set of flow channels becomes spent, it can be replaced by removing a header.