| 摘要 |
<PICT:0433559/IV/1> Formaldehyde is produced by passing a mixture of methane, oxygen, and less than 1 per cent of nitrogen oxides (reckoned as NO), over a solid catalyst comprising an oxide or carbonate of aluminium, chromium, vanadium, molybdenum, tungsten, manganese, nickel, or cobalt and an oxide or carbonate of beryllium, magnesium, calcium, barium, strontium, cadmium, mercury, titanium, geranium, zirconium, tin, cerium, lead, or thorium, at 600--750 DEG C. In examples, the catalyst consists of (1) barium oxide, calcium carbonate, cobalt oxide, zirconium oxide, and magnesium carbonate; (2) magnesium carbonate, alumina, cadmium oxide, and cerium oxide. In the apparatus shown methane and air are delivered by pumps 1 and 2 respectively to a container 3, the mixture, which receives nitrogen oxide from a pipe 8, being led to the reaction chamber 7 which resembles a tubular boiler in which the heating-gas is admitted at 9 and passes through the tubes 10 to an outlet pipe 12, and may give up its remaining heat to the gas mixture in the container 3. The catalyst is arranged between the heating-tubes in the path of the reaction gas mixture and the products pass through exit 13, pipes 14 and 15 by way of a cooler 16 to a receiver 17 from which the vapours and gases pass to a washer 19, the washing-liquor being collected in a vessel 22 and returned to the washer until sufficiently concentrated, when it is led to a still 28 for further concentration. Specifications 375,314 and 405,763 are referred to.
|
