The description of the item 3815199010 of Germany HScode: Supported catalysts, n.e.s. (excl. supported catalysts with precious metal, a precious-metal compound, nickel or a nickel compound as the active substance and catalysts in the form of grains of which >= 90% by weight have a particle-size <= 10 micrometres, consisting of a mixture of oxides on a magnesium-silicate support, containing by weight >= 20% but <= 35% of copper and >= 2% but <= 3% of bismuth and of an apparent specific gravity of >= 0,2 but <= 1,0) : Catalysts consisting of chromium trioxide, dichromium trioxide or organometallic compounds of chromium, fixed on a silicon dioxide support with a pore volume of 2cm3/g or more (as determined by the nitrogen absorption method)