Patent GB-958784-A (GB)
Title: Process for the production of catalytically active coatings on reaction chambers
IPC: B01J23/46
Filed: 1960-10-05
Abstract: In a process for the production of hydrocyanic acid from ammonia and methane at temperatures from 900 DEG  to 1400 DEG  C., catalytically active coatings are produced on the walls of the reaction chambers by a process comprising treating the walls with a hydrochloric acid solution containing aluminium and a metal of the platinum group (Ru, Rh, Pd, Os, Ir, Pt), evaporating the solvent and drying the deposited material, repeating the treating, evaporating, and drying until sufficient layers of the platinum group metal and Al2O3 have been deposited, heating the coating obtained up to 800 DEG  C. in a current of a reducing gas (e.g. NH3, H2) and activating the resulting catalyst by heating at 900 DEG  to 1400 DEG  C. for several days in such a way that first only ammonia is passed over the catalyst and that methane is added at such a rate that the methane content in the gases, after passage over the catalyst and removal of NH3 and HCN, never exceeds 1% by volume and that not earlier than after 4 days a volume ratio of NH3 to NH4 of 1 to 0.7-0.8 is reached. The reaction chamber may comprise tubes of sillimanite or clay, and may be in the form of two concentric tubes forming an annular space through which the gases pass, all surfaces with which the gases come into contact being coated with the catalyst.  In examples the catalyst is a dispersion of platinum and ruthenium in alumina.ALSO:A process for the production of catalytically active coatings on the walls of reaction chambers for the synthesis of hydrocyanic acid from ammonia and methane at temperatures from 900-1400  DEG C. comprises treating the walls with a hydrochloric acid solution containing aluminium and a metal of the platinum group (Ru, Rh, Pd, Os, Ir, Pt), evaporating the solvent and drying the deposited material, repeating the treating, evaporating, and drying until sufficient layers of the platinum group metal and Al2O3 have been deposited, heating the coating obtained up to 800  DEG C. in a current of a reducing gas (e.g. NH3, H2) and activating the resulting catalyst by heating at 900-1400  DEG C. for several days at such a rate that first only ammonia is passed over the catalyst and that methane is added at such a rate that the methane content in the gases, after passage over the catalyst and removal of NH3 and HCN, never exceeds 1% by volume and that not earlier than after 4 days a volume ratio of NH3 to CH4 of 1:0.7-0.8 is reached. The reaction chamber may comprise tubes of sillimanite or clay, and may be in the form of two concentric tubes forming an annular space through which the gases pass, all surfaces with which the gases come into contact being coated with the catalyst.  In examples the catalyst is a dispersion of platinum and ruthenium in alumina.ALSO:A process for the production of catalytically active coatings on the walls of reaction chambers for the synthesis of hydrocyanic acid from ammonia and methane at temperatures from 900 to 1400  DEG C. comprises treating the walls with a hydrochloric acid solution containing aluminium and a metal of the platinum group (Ru, Rh, Pd, Os, Ir, Pt), evaporating the solvent and drying the deposited material, repeating the treating, evaporating, and drying until sufficient layers of the platinum group metal and Al2O3 have been deposited, heating the coating obtained up to 800  DEG C. in a current of a reducing gas (e.g. NH3, H2) and activating the resulting catalyst by heating at 900-1400  DEG C. for several days in such a way that first only ammonia is passed over the catalyst and that methane is added at such a rate that the methane content in the gases, after passage over the catalyst and removal of NH3 and HCN1 never exceeds 1% by volume and that not earlier than after four days a volume ratio of NH3 to CH4 of 1 to 0,7-0,8 is reached.  The reaction chamber may comprise tubes of sillimanite or clay, and may be in the form of two concentric tubes forming an annular space through which the gases pass, all surfaces with which the gases come into contact being coated with the catalyst.  In examples the catalyst is a dispersion of platinum and ruthenium in alumina.