PRODUCTION OF PLATINUM-NITRIC ACID AQUEOUS SOLUTION AND EXHAUST GAS PURIFYING CATALYST

摘要

PURPOSE:To produce a platinum-nitric acid aqueous and an exhaust gas purifying catalyst of high efficiency using the same aqueous solution where platinum in charge of the purifying function is surely adsorbed on a catalyst used for purifying exhaust gas and which has properties of low purifying temperature and good purifying efficiency in catalyst performance. CONSTITUTION:In a method for producing a platinum-nitric acid aqueous solution where dinitroamino platinum is dissolved in an aqueous solution of nitric acid and then heated and aged, dinitroamino platinum of 350-600g/l expressed in terms of platinum is dissolved in the aqueous solution of nitric acid of 450-700g/l nitric acid concentration and platinum in the solution is converted from divalent to quadrivalent by boiling it to 170 deg.C to obtain the platinum-nitric acid aqueous solution. After the obtained aqueous solution is diluted to a prescribed concentration, it is adsorbed on a ceramic carrier and the platinum nitrate is given thermal decomposition and reduction to make platinum carried on the carrier, allowing an exhaust gas purifying catalyst to be formed.