Abstract: Three-dimensional knitted catalyst gauzes made from noble metals have recently come into use for ammonia oxidation and other gaseous reactions. Particularly high yields accompanied by a stable course of the reaction and an extended service life of the catalyst gauze are achieved if the catalyst gauzes are knitted in two or more layers and the layers are connected together by pile threads. Important features are the largest possible number of pile threads per unit area and the alignment thereof as parallel as possible to the direction of flow of the reaction gases.

Abstract: Wires of platinum containing 4 to 12% rhodium or 4 to 12% of palladium and rhodium (4 to 12% being in reference to the sum of palladium and rhodium and not the percent values for each individually) and wires of palladium containing 2 to 15% nickel or 2 to 15% copper or 2 to 15% of nickel and copper (2 to 15% being in reference to the sum of nickel and copper) and having a diameter of 50 to 120 .mu.m, a tensile strength of 900 to 1050 N/mm.sup.2 and an elastic limit of 0.5 to 3% are used for the knitting of round nets for use as catalysts in the oxidation of ammonia and as recovery nets for platinum metals. A flat knitting machine with a gauge of 3.63 to 1.81 mm is also used whereby the loop length is 2 to 6 mm and wherein the loop or width gauge corresponds with the knitting machine gauge so as to provide a loop width of 1.81 to 3.63 mm.