Platinum/cerium aluminum-molecular sieve catalyst for catalytic oxidation of ammonia gas and preparation method thereof

Abstract

The invention provides a platinum / cerium aluminum-molecular sieve catalyst for catalytic oxidation of an ammonia gas. Cordierite ceramic is utilized as a carrier for the platinum / cerium aluminum-molecular sieve catalyst, the surface of the carrier is coated with a catalyst layer, and the catalytic active site of the catalyst layer consists of a noble metal platinum, a cerium-aluminum composite oxide and a neodymium-modified molecular sieve; the mass ratio of the cerium-aluminum composite oxide to the neodymium-modified molecular sieve to the noble metal platinum is (20-80):(20-80):(0.01-0.1), and the mass ratio of cerium oxide and aluminum oxide in the cerium-aluminum composite oxide is (1-3):(1-5); the mass ratio of neodymium oxide and a molecular sieve in the neodymium-modified molecular sieve is (1-10):(90-100). The platinum / cerium aluminum-molecular sieve catalyst is also capable of achieving wide low-temperature activity window, good catalytic activity and high selectivity even at a high space velocity (SV), and is capable of effectively restraining generation of secondary pollutants of N2O, NO and NO2. The invention further provides a preparation method of the platinum / cerium aluminum-molecular sieve catalyst.

Description

technical field [0001] The invention belongs to the technical field of catalysts, and relates to a catalyst for catalytic oxidation of ammonia and a preparation method thereof, in particular to a platinum / cerium aluminum-molecular sieve catalyst for catalytic oxidation of ammonia and a preparation method thereof. Background technique [0002] Diesel engines are being used more and more widely due to their low fuel consumption and high power. However, the high temperature and high pressure in the cylinder of diesel engines will produce a large amount of nitrogen oxides, which has brought serious environmental problems. At present, my country basically adopts Selective Catalytic Reduction (SCR) to treat nitrogen oxides produced by diesel engines, and the most widely used reducing agent is urea aqueous solution, which is hydrolyzed to generate ammonia. In order to meet stricter NOx emission standards, the following two methods are mainly adopted in the world: (1) injecting more...

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Problems solved by technology

[0012] CN 103476495A discloses an ammonia oxidation catalyst and an exhaust gas purification device using it and its use method. It adopts double-layer coating, the lower layer is an inorganic material loaded with precious metals, and the upper layer is a molecular sieve catalyst. 3 It has higher catalytic oxidation activity, but also produces a higher concentration of N 2 O and NO x

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