Pd-based NOX adsorbent and preparation method and application thereof

Abstract

The invention discloses a preparation method of a Pd-based NOX adsorbent. The preparation method comprises the following steps: S1, performing ammonium ion exchange on a zeolite molecular sieve to obtain an ammonium type molecular sieve; S2, performing palladium ion exchange on the ammonium type molecular sieve to obtain a first precursor; S3, dropwise adding an aqueous solution containing palladium ions into the first precursor, uniformly mixing, standing for dipping and drying to obtain a second precursor; and S4, roasting the second precursor and performing hydrothermal activation to obtainthe Pd-based NOX adsorbent. The invention also discloses the Pd-based NOX adsorbent which is prepared according to the preparation method of the Pd-based NOX adsorbent. The invention also discloses an application of the Pd-based NOX adsorbent in adsorption of automobile exhaust. The Pd-based NOX adsorbent prepared has the functions of efficiently and quickly adsorbing and storing NOX at low temperature and thermally desorbing NOX at high temperature and can realize harmless treatment of NOX in a cold start stage of a diesel engine.

Description

technical field [0001] The invention relates to the technical field of adsorbents, in particular to a Pd-based NO X Adsorbent and its preparation method and application. Background technique [0002] Since 2015, the problem of vehicle emissions has continued to ferment under the influence of domestic air pollution. In order to reduce exhaust pollution, my country has also accelerated the rigid requirements for exhaust emissions in recent years. In 2014, the National IV standard was introduced. On July 1, 2017, all heavy-duty diesel vehicles manufactured, imported, sold and registered in my country must meet National V standard requirements. As early as the end of 2016, the Ministry of Environmental Protection and the General Administration of Quality Supervision, Inspection and Quarantine jointly issued the "Light Vehicle Pollutant Emission Limits and Measurement Methods (China's Sixth Stage)", and the National VI standard will be divided into a and b two emission limits p...

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Problems solved by technology

[0008] The Pd-based NO disclosed in the current literature X In the technical route of the adsorption material synthesis, there are mainly ion exchange method, equal volume impregnation method, excessive impregnation method, solid-state ion exchange method, etc. The ion exchange method will cause the Pd ion exchange rate to be too low, and most of the Pd ions will remain in the reaction solution. Among them, it causes loss, environmental pollution, and recovery is difficult; equal volume impregnation method and excessive impregnation method will cause Pd ions to agglomerate, resulting in part of Pd being oxidized to PdO, losing adsorption-desorption NO X ability; the solid-state ion exchange method is difficult to operate and is not conducive to large-scale production

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