Core-shell structure catalyst for efficient and synergistic removal of NOx and toluene and preparation method thereof

Abstract

The invention discloses a core-shell structure catalyst for efficient and synergistic removal of NOx and toluene and a preparation method thereof. The catalyst comprises the following components by mass percentage: 0.5%-4% of Cu, 20-30% of CeO2 and the balance carrier Beta molecular sieve. The preparation method includes: taking Cu / Beta as the core, coating the Cu / Beta core layer with CeO2, and conducting drying and calcining to obtain the Cu / Beta@CeO2 core-shell catalyst. According to the invention, Cu / Beta with strong toluene adsorption and desorption capabilities is adopted as the core, andat the same time Cu can reduce the ignition temperature of the catalyst; and secondly, the strong oxygen storage capacity of the CeO2 shell can prevent carbon deposit on the catalyst surface, thus protecting the active components of the core layer and forming a special interfacial effect with the core layer, and further improving the catalytic activity of the catalyst for toluene at low temperature.

Description

technical field [0001] The invention relates to the exhaust gas purification of diesel vehicles, in particular to a x A core-shell structure catalyst with efficient synergistic removal with toluene and a preparation method thereof. Background technique [0002] Due to the widespread use of diesel vehicles, the pollution caused by the exhaust gas is becoming more and more serious, and countries all over the world pay more and more attention to the purification treatment of diesel vehicle exhaust. Especially in diesel vehicle exhaust, NO x It is very destructive to the natural environment and human health, and will cause major environmental problems such as photochemical smog, acid rain, greenhouse effect and ozone layer hole effect; although the total amount of HC emissions is not much, the amount of toluene in benzene series is prominent. It is more harmful to the human body and can also be indirectly used as O 3 The precursors of smog and smog are harmful to the environm...

AI Technical Summary

Problems solved by technology

The main reason is that vanadium-based catalysts still have some unavoidable shortcomings: the effective working window (300-400°C) of this type of catalyst cannot completely cover the temperature range of diesel vehicle exhaust (200-450°C); the anti-carbon deposition performance of vanadium-based catalysts worse, and V 2 o 5 Has strong biological toxicity; NH at high temperature (450°C) 3 The non-selective oxidation of NO x The purification rate drops rapidly, and a large amount of by-product N is produced 2 O, leading to the main product N 2 The selectivity is significantly reduced, and it also causes secondary pollution to the atmosphere

However, molecular sieve catalysts tend to have carbon on the surface due to too strong acidity, but ammonia gas is difficult to adsorb on the surface of the catalyst due to too weak acidity.

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