Abstract: A compact catalytic reactor defines a multiplicity of first and second flow channels arranged alternately, the first flow channels being no more than 10 mm deep and providing flow paths for combustible reactants, and containing a catalyst structure (20) to catalyze combustion of the reactants, and having at least one inlet for at least one of the reactants. The first flow channel also includes an insert (40 or 60) adjacent to each inlet, this insert not being catalytic to the combustion reaction; the insert may define gaps which are narrower than the maximum gap size for preventing flame propagation.

Abstract: A compact catalytic reactor defines a multiplicity of first and second flow channels arranged alternately, the first flow channels being no more than 10 mm deep and providing flow paths for combustible reactants, and containing a catalyst structure (20) to catalyse combustion of the reactants, and having at least one inlet for at least one of the reactants. The first flow channel also includes an insert (40 or 60) adjacent to each inlet, this insert not being catalytic to the combustion reaction; the insert may define gaps which are narrower than the maximum gap size for preventing flame propagation.