Process for removing nitrogen oxides from exhaust gases
Реферат: 1381370 Inorganic substances KNAPSACK AG 29 Dec 1972 [30 Dec 1971] 60037/72 Heading C1A [Also in Division F1] A process for reducing the nitrogen oxides, in an exhaust gas, to nitrogen comprises contacting the nitrogen oxide-containing gas, in admixture with at least a stoichiometric proportion based on the nitrogen content of the gas, of hydrogen and/or carbon monoxide and/or a gaseous hydro-carbon reductant, with a catalyst comprising a homogeneous mixture of oxides and/or aluminates of copper, nickel and manganese at temperatures between 150 and 1100 C. The exhaust gases are those emanating from an I.C. engine or from the production of nitric acid. In the former case the reducing gas will be present in the exhaust gas and in the latter case is added as natural gas, methane or propane. The ratio of the metal compounds one to another is between 0À1 to 1À0 and is preferably 1 : 1 : 1. The homogeneous mixture is pelletized or is deposited on an inert carrier i.e. aluminium oxide, spinel, mullite, cordierite or gehlenite, in which case the amount of catalyst present is 2 to 40% by wt., calculated as metal oxides of the overall weight of catalyst and carrier, but is preferably 5 to 15% by wt. The catalyst is made by impregnating the carrier with an aqueous solution, saturated while hot, of copper, nickel and manganese nitrates, drying the impregnated carrier at 90 to 150 C. and heating the dry carrier to 200 to 450 C. to decompose the nitrates to form the metal oxides. To form aluminates, the mixture of aluminium oxide and metal oxides is heated to 900 to 1100 C. The aluminium oxide is α-Al 2 O 3 produced by annealing α-Al(OH) 3 at 1000 C. Under experimental conditions which included artificial ageing by operating at cyclically varying temperatures between 265 and 950 C., the catalyst was found to convert 95% of the nitrogen oxides, in an exhaust gas, to nitrogen when operated finally at 950 C.
Process for preparation of catalyst for cleaning exhaust gases and catalyst prepared by the process
Номер патента: US4448895A. Автор: Kiyoshi Yonehara,Tetsuji Ono,Shin Yamauchi,Kazuo Tsuchitani. Владелец: NIPPON SHOKUBAI CO LTD. Дата публикации: 1984-05-15.