Preparation method for synthesizing Cu-SAPO-34 molecular sieve based catalyst through hydrogen fluoride modified one-step method

Abstract

The invention provides a preparation method for synthesizing a Cu-SAPO-34 molecular sieve based catalyst through a hydrogen fluoride modified one-step method. The method comprises the steps that an aluminum source, orthophosphoric acid, a silicon source, copper sulfate, tetraethylenepentamine and hydrogen fluoride are sequentially added to deionized water to be fully stirred, gel is obtained and placed in a hydrothermal reaction kettle, reacting is carried out for 0.5-5 days at the temperature of 150 DEG C to 200 DEG C, and after cooling, filtering, washing and drying are carried out, calcination is carried out at the temperature of 550 DEG C to obtain the Cu-SAPO-34 molecular sieve based catalyst. Cu-SAPO-34 is synthesized in situ through the hydrogen fluoride modified one-step method, the degree of crystallinity of a molecular sieve is improved, SAPO-5 and other mixed crystals are prevented from being generated, the crystallization speed of the molecular sieve is increased, crystallization time is only 1 / 2-1 / 3 that of a molecular sieve without hydrogen fluoride, structure defect sites are reduced, the acid site density of the molecular sieve is increased, an NH3-SCR temperature window of the catalyst is widened, and the hydrothermal stability performance of the catalyst is improved.

Description

technical field [0001] The invention belongs to the field of chemistry and chemical engineering, and relates to a preparation method of Cu-SAPO-34 (copper-phosphorus-silicon-aluminum molecular sieve), in particular to a hydrogen fluoride (HF) modified one-step method for synthesizing Cu-SAPO-34 (copper-phosphorus-silicon-aluminum molecular sieve) ) catalyst method and the catalyst prepared by the method and the catalyst application thereof, the Cu-SAPO-34 (copper-containing phosphorus silicon aluminum molecular sieve) catalyst is used for nitrogen and oxygen in the diesel vehicle aftertreatment (Urea-SCR) system catalyst Compound purification process. Background technique [0002] Chabazite (CHA) structure molecular sieve, also known as chabazite, belongs to the rhombohedral crystal system and has a three-dimensional eight-membered ring channel system. The structure contains cage columns composed of six-membered rings and CHA cages alternately. It is 0.38nm×0.38nm, which be...

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Problems solved by technology

[0003] CN102259892A discloses a metal-amine-complex as a template to synthesize a phosphorus-silicate-aluminum molecular sieve catalyst, which avoids the introduction of active components and requires the SAPO-34 carrier and a certain concentration of copper salt precursor solution to be exchanged at a certain temperature, Filtration, washing, drying and high-temperature calcination process, but the introduction of a large amount of copper amine complexes in the synthesis of Cu-SAPO-34 causes the content of active component copper in the catalyst to be too high; Corma et al. Ethylamine was used as a double template to synthesize Cu-SAPO-34 molecular sieve catalyst, and the copper loading was regulated by controlling the input ratio of the two templates. However, it was necessary to add SAPO-34 seed crystals during the synthesis process to improve the crystallinity of the catalyst. The Cu-SAPO-34 catalyst has poor hydrothermal stability, and its activity decreased significantly after hydrothermal aging at 750 °C

(Martinez-Franco, R. et al. Rational direct synthesis methodology of very active and hydrothermally stable Cu-SAPO-34 molecular sieves for the SCR of NO x , AppliedCatalysisB:Environmental, 2012,127:273); CN104209141A and CN103818927A disclose a kind of method that adopts the Cu-SAPO-34 catalyst of double templating agent one-step synthesis high hydrothermal stability, but the above-mentioned method crystallization reaction time is long, The grain size cannot be controlled, and miscellaneous crystals appear during the crystallization process

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