The current application discloses a method for producing a porous catalyst, the method comprising providing a powder of metal particles with a specific size; mixing into the powder of metal particles spacer spheres with a fixed diameter less than that of the metal particles; placing the metal-particle/spacing-sphere mixture in a ceramic container; heating the mixture in an oven, furnace or microwave oven to sinter the metal particles and fuse them to a solid matrix; and removing the spacing spheres either by solvolysis or pyrolysis.