Method for preparing Pd-only catalyst used for tail gas purification of universal minitype petrol engines

Abstract

The invention relates to a method for preparing Pd-only catalyst used for tail gas purification of universal minitype petrol engines and belongs to the technical field of tail gas catalysis purification of universal minitype petrol engines. The Pd-only catalyst only contains noble metal Pd and does not contain noble metal Pt or Rh with the cost far higher than that of Pd, so that the cost of tail gas purification catalyst for universal minitype petrol engines can be reduced; a metal carrier is pre-treated through roasting at the relatively low temperature of 400 to 700 DEG C, pseudo-boehmite binding agent is added in coating slurry, and a bonding layer not containing noble metal or oxygen storage material does not need to be applied in advance, but a catalysis coating containing noble metal is applied on the metal carrier directly, so that the preparation technology of the tail gas purification catalyst for universal minitype petrol engines can be simplified; and cerium-rich tombarthite oxygen storage material and alumina material with high specific surface area are added in the coating, so that the activity and the durability of the Pd-only catalyst for tail gas purification of universal minitype petrol engines can be improved, the consumption of Pd can be reduced, and a universal minitype petrol engine with the Pd-only catalyst provided by the invention can satisfy the requirements of emission regulations.

Description

technical field [0001] The invention relates to a single Pd catalyst for purifying tail gas of a general small gasoline engine and a preparation method thereof, and belongs to the technical field of catalytic purification of tail gas of a general small gasoline engine. Background technique [0002] The supporting equipment for general small gasoline engines can be used for water pumps, generator sets, mist powder sprayers, brush cutters, wind fire extinguishers, compactors, demolition tools, wool shears, ATVs, golf carts, sleds, outboard motors, Scooters, aircraft models, boat models, etc. are involved in many fields such as industry, agriculture, insurance management, entertainment, transportation, emergency rescue and disaster relief, garden machinery, etc. With the continuous growth of my country's economy, domestic demand is gradually increasing, but it is still Mainly export to the international market, among which the European and American markets account for more than h...

AI Technical Summary

Problems solved by technology

For four-stroke general-purpose small gasoline engines, through air-fuel ratio, ignition timing, and compression ratio adjustments, HC+NOx emissions can meet the first and second stages of European and American emission standards, but cannot meet the EPA III emission requirements for HC+NOx

The two-stroke general-purpose small gasoline engine has a short ventilation process, which is only about 1 / 3 of the four-stroke engine at the same speed, and the intake and exhaust processes are carried out almost simultaneously. The fresh air may be lost, and the exhaust gas is not easy to clean. These escaping fresh oil and gas The mixed gas leads to high HC emissions, and the original HC+NOx emissions cannot meet the emission requirements of EPAII

[0022] At present, the general-purpose small gasoline engine exhaust gas purification catalysts mostly contain Pt, Pd and Rh three noble metals, which lead to high catalyst costs; in order to increase the firmness of the metal carrier and the coating, the metal carrier must be roasted at 800-1100 ℃ pretreatment, and the coating contains Before the catalytic coating of precious metals, a bonding layer that does not contain precious metals and oxygen storage materials must be pre-coated, which makes the catalyst preparation process complicated and the equipment cost high; with the formulation of domestic regulations and the increasingly stringent foreign European and American regulations, Changes in catalyst activity and durability are required