CN104307564B

CN104307564B - A kind of Cu-SAPO-34 catalyst of auxiliary agent doping and its preparation method and application

Info

Publication number: CN104307564B
Application number: CN201410455295.1A
Authority: CN
Inventors: 李永丹; 董雪松; 王继辉; 赵化望
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2014-09-09
Filing date: 2014-09-09
Publication date: 2016-07-20
Anticipated expiration: 2034-09-09
Also published as: CN104307564A

Abstract

The present invention discloses Cu SAPO 34 catalyst of a kind of auxiliary agent doping and its preparation method and application, prepares Cu SAPO 34 catalyst initially with liquid ion exchange, then uses equi-volume impregnating to carry out the doping of auxiliary agent, uses it for NH₃SCR reacts, and improves the catalysis activity of original Cu SAPO 34 catalyst.This catalyst environmental friendliness, catalyst preparation process is simple, it is easy to operates and amplifies.

Description

A kind of Cu-SAPO-34 catalyst of auxiliary agent doping and its preparation method and application

Technical field

The invention belongs to catalyst technical field, more particularly, relate to a kind of ammonia SCR nitrogen oxidation Catalyst of thing and its preparation method and application.

Background technology

Nitrogen oxides (NOx) mainly includes N₂O,NO,N₂O₃,NO₂,N₂O₄Deng, it is one of the major pollutants of air, It is acid rain formation, depletion of the ozone layer, the main reason of photochemical pollution.The problem of environmental pollution pair caused in view of NOx Health and ecological environment constitute grave danger, and country has issued relevant exhaust emission standard and strictly limited NOx's Discharge, that reduces NOx arranges into the topic jointly paid close attention to for people.SCR (SCR) be currently by It has been recognized that for eliminating one of maximally effective technology of NOx.SCR technology is to join in aerofluxus by reducing agent, uses and is suitable for Catalyst, make NOx and reducing agent react, generate nontoxic, harmless nitrogen and steam, thus reduce NOx Discharge.NH₃The master equation of-SCR reaction is as follows:

4NH₃+4NO+O₂→4N₂+6H₂O

4NH₃+2NO₂+O₂→3N₂+6H₂O

4NH₃+2NO+2NO₂+O₂→4N₂+6H₂O

SCR technology it is crucial that select excellent catalyst.At present, commercial SCR catalyst is mainly supported on anatase The TiO of type₂On, with WO₃Or MoO₃Modify V base catalyst (ChoSM.Chem.Eng.Prog., 1994,90 (1): 39-45).This type of catalyst has the features such as high activity, high selectivity, but active temperature is between 350-450 DEG C, I.e. low temperature NOx elimination rate variance, activity warm area are narrow.Additionally V₂O₅N relatively low under the toxicity of itself and this catalyst high temperature₂Choosing Selecting property also limit its further application.

Summary of the invention

It is an object of the invention to overcome the deficiencies in the prior art, it is provided that the Cu-SAPO-34 catalyst of a kind of auxiliary agent doping And its preparation method and application, adulterate in Cu-SAPO-34 catalyst auxiliary agent use it for NH₃-SCR reacts, and changes It is apt to the catalysis activity of original Cu-SAPO-34 catalyst.This catalyst environmental friendliness, catalyst preparation process is simple, Easily operated and amplify.

Technical scheme is achieved by following technical proposals:

The Cu-SAPO-34 catalyst of a kind of auxiliary agent doping, with the silicoaluminophosphamolecular molecular sieves of Copper Ion Exchange as carrier, helps The doping of agent is the 0.5～20wt% of carrier quality, and described auxiliary agent is metal Ce, Fe, Cr or Cd.

In above-mentioned catalyst, the doping of preferred promoter is 2 10wt% of carrier quality, and auxiliary agent is with the shape of oxide Formula exists.

In above-mentioned catalyst, the doping of preferred promoter Ce is the 2wt% of carrier quality, and auxiliary agent is with CeO₂Form Exist.

The preparation method of above-mentioned catalyst, is prepared as steps described below:

Step 1, uses liquid ion exchange to prepare Cu-SAPO-34 catalyst, will be with the SAPO of reactive hydrogen Molecular sieve and (NH₄)₂SO₄Aqueous solution is sufficiently mixed uniformly, and uses ammonia regulation system pH to 3.0-4.0, at 70 80 DEG C Stirred in water bath is fully reacted, so that reactive hydrogen is by NH₄ ⁺Exchange, then will be by NH₄ ⁺Silicoaluminophosphamolecular molecular sieves after exchange with Copper sulfate solution is sufficiently mixed uniformly, and uses ammonia regulation system pH to 3.0-4.0, stirs in 70 80 DEG C of water-baths Mix fully reaction, so that NH₄ ⁺Exchanged by elemental copper, after filtering and washing, forge for 500 550 DEG C in air atmosphere Burn 35 hours, i.e. obtain Cu-SAPO-34 catalyst；

Step 2, uses equi-volume impregnating to carry out the doping of auxiliary agent, and the nitrate i.e. selecting promoter metal is soluble in water with shape Become aqueous solution, be added thereto to the Cu-SAPO-34 catalyst of step 1 preparation, stir to complete wetting in air gas Stand at atmosphere room temperature 20 25 DEG C, so that auxiliary agent reaches doping, after drying, in air atmosphere 500 550 DEG C Calcine 35 hours, i.e. obtain the Cu-SAPO-34 catalyst of auxiliary agent doping.

In above-mentioned preparation method, in described step 1, by silicoaluminophosphamolecular molecular sieves and (NH with reactive hydrogen₄)₂SO₄ Aqueous solution fully reacts at least 2h 70 80 DEG C of stirred in water bath, and preferably 2 8h, so that reactive hydrogen is by NH₄ ⁺Exchange.

In above-mentioned preparation method, in described step 1, will be by NH₄ ⁺Silicoaluminophosphamolecular molecular sieves after exchange and copper sulfate Aqueous solution fully reacts at least 10h, preferably 12 24h 70 80 DEG C of stirred in water bath.

In above-mentioned preparation method, in described step 2, stand at least 10h, preferably 12 24h.

The application in selective catalysis of the above-mentioned catalyst, uses 40-60 mesh catalyst, and atmosphere is: 500ppm NO, 500ppm NH₃, 5%O₂, N₂For Balance Air；Total gas flow is 500ml/min, total empty time be 50000h^-1；Instead Answering temperature is 150～550 DEG C, preferably 250 400 DEG C.

In the inventive solutions, SAPO-34 molecular sieve (silicoaluminophosphamolecular molecular sieves) is by SiO₂,AlO₂ ^-And PO₂ ⁺ Three kinds of tetrahedrons are connected with each other and form, and have the structure of chabasie, have moderate acid and good heat stability and water Heat stability, uses liquid ion exchange that H/SAPO-34 is prepared as Cu-SAPO-34, then mixes carrying out auxiliary agent Miscellaneous.Compared with prior art, in the inventive solutions, the addition of auxiliary agent changes the catalysis activity of catalyst, Relatively different elements improve at most as auxiliary agent catalyst activity as auxiliary agent, cerium.Cerium makees auxiliary agent catalyst agent activity The highest, wherein doping is that 2wt% catalysis activity is best.In the range of 200～450 DEG C, can be by NOx more than 90% Conversion.The raw material of catalyst is cheap, environmental friendliness.Catalyst preparation process is simple, it is easy to operates and amplifies.

Accompanying drawing explanation

Fig. 1 is the XRD spectra of the catalyst of different auxiliary agent doping.

Fig. 2 is the XRD spectra of the catalyst not being both doping.

Fig. 3 is the SCR activity test figure of 2wt.%CeCu-SAPO-34 catalyst.

Detailed description of the invention

Technical scheme is further illustrated below in conjunction with specific embodiment.

Silicoaluminophosphamolecular molecular sieves H/SAPO-34 with reactive hydrogen is purchased from Catalyst Factory, Nankai Univ, and remaining reagent is sky Recovery development in science and technology company limited of Jinshi City provides.

Embodiment 1

The preparation of 2wt.%CeCu-SAPO-34 catalyst

1. being poured into by 10g H/SAPO-34 in the there-necked flask of 500ml, adding 100ml concentration is the (NH of 23.4wt.%₄)₂SO₄ Aqueous solution, with ammonia that concentration is 2mol/L regulation pH to 3.0-4.0,80 DEG C of stirring in water bath 2 hours, sucking filtration, washing And in air atmosphere 90 DEG C be dried 16 hours, obtain NH₄ ⁺/ SAPO-34 powder.

2. the NH that will obtain₄ ⁺/ SAPO-34 sample is poured in the there-necked flask of 250ml, and adding 50ml concentration is the sulfur of 0.1mol/L The aqueous solution of acid copper, with ammonia that concentration is 2mol/L regulation pH to 3.0-4.0,70 DEG C of stirring in water bath 12 hours, take out Filter, washing and in air atmosphere 90 DEG C be dried 16 hours, then Muffle furnace 550 DEG C calcining 4 hours, obtain Cu-SAPO-34 catalyst.

3. weigh 0.130g Ce (NO₃)₃·6H₂O is dissolved in 1.4ml deionized water, weighs 2gCu-SAPO-34 catalyst and pours into molten In liquid, stirring to complete wetting, air atmosphere room temperature stands 12 hours, and 120 DEG C are dried 12 hours, finally in Muffle 550 DEG C of stove is calcined 4 hours, obtains the CeCu-SAPO-34 catalyst that cerium dopping amount is 2wt.%.

Embodiment 2-4

In the case of other experiment conditions are identical with embodiment 1, by 0.130gCe (NO₃)₃·6H₂O changes 0.322g into Fe(NO₃)₃·9H₂O, 0.339g Cr (NO₃)₃·9H₂O, 0.115g Cd (NO₃)₂·4H₂O, the doping obtaining auxiliary agent is equal For the FeCu-SAPO-34 of 2wt.%, CrCu-SAPO-34, CdCu-SAPO-34 catalyst.

(XRD uses the D8-Focus of Brooker AXS company limited of Germany to the XRD spectra of each catalyst above-mentioned as shown in Figure 1 Type diffractometer, Cu target ceramic X-ray tube, 2 θ measurable angle ranges are 5～80 °, and scanning speed is 8 °/min, and test sample is Powder, lower same).The doping of auxiliary agent makes the characteristic peak intensity of SAPO-34 reduce, and wherein the catalyst of Ce doping occurs CeO₂Characteristic peak, other catalyst are then not detected by the peak of corresponding oxide.

Embodiment 5-9

In the case of other experiment conditions are identical with embodiment 1, by 0.130g Ce (NO₃)₃·6H₂O changes 0.047g into, 0.095g, 0.526g, 1.212g, 2.321g Ce (NO₃)₃·6H₂O, obtains cerium dopping amount and is respectively 0.5wt.%, 1wt.%, The CeCu-SAPO-34 catalyst of 5wt.%, 10wt.%, 20wt.%.

The XRD spectra of each catalyst above-mentioned is as shown in Figure 2.When the doping of cerium is less than 2wt.%, spectrogram is not detected by CeO₂Characteristic peak, when cerium doping more than 2wt.% time, spectrogram starts CeO occur₂Characteristic peak, and along with The increase peak intensity of cerium dopping amount also increases.

Embodiment 10

Catalyst is carried out active testing by SCR catalytic evaluation device, weighs embodiment 1 catalyst 0.475g. The activity characterization condition of catalyst is: 40-60 mesh catalyst；Atmosphere is: 500ppm NO, 500ppm NH₃, 5%O₂, N₂For Balance Air；Total gas flow is 500ml/min, total empty time be 50000h^-1；Reaction temperature is 150～550 ℃.Catalysis activity is as it is shown on figure 3, this catalyst improves a lot compared to Cu-SAPO-34 catalyst, activity.

Embodiment 11-18

In the case of other reaction conditions are same as in Example 10, the catalyst in embodiment 2-9 is used to carry out SCR activity survey Examination.Obtained catalysis activity is as shown in table 1.

Table 1 different catalysts conversion rate of NOx

Above the present invention is done exemplary description, it should explanation, in the case of without departing from the core of the present invention, Any simple deformation, amendment or other those skilled in the art can not spend the equivalent of creative work all to fall Enter protection scope of the present invention.

Claims

1. the Cu-SAPO-34 catalyst of an auxiliary agent doping, it is characterized in that, with the silicoaluminophosphamolecular molecular sieves of Copper Ion Exchange as carrier, the doping of auxiliary agent is the 0.5～20wt% of carrier quality, described auxiliary agent is metal Fe, Cr or Cd, and is prepared as steps described below:

Step 1, uses liquid ion exchange to prepare Cu-SAPO-34 catalyst, will be with the silicoaluminophosphamolecular molecular sieves of reactive hydrogen and (NH₄)₂SO₄Aqueous solution is sufficiently mixed uniformly, and uses ammonia regulation system pH to 3.0-4.0, fully reacts 70 80 DEG C of stirred in water bath, so that reactive hydrogen is by NH₄ ⁺Exchange, then will be by NH₄ ⁺Silicoaluminophosphamolecular molecular sieves after exchange and copper sulfate solution are sufficiently mixed uniformly, and use ammonia regulation system pH to 3.0-4.0, fully react 70 80 DEG C of stirred in water bath, so that NH₄ ⁺Exchanged by elemental copper, after filtering and washing, calcine 35 hours for 500 550 DEG C in air atmosphere, i.e. obtain Cu-SAPO-34 catalyst；

Step 2, equi-volume impregnating is used to carry out the doping of auxiliary agent, the nitrate i.e. selecting promoter metal is soluble in water to form aqueous solution, it is added thereto to the Cu-SAPO-34 catalyst of step 1 preparation, stir and stand at air atmosphere room temperature 20 25 DEG C to complete wetting, so that auxiliary agent reaches doping, after drying, air atmosphere is calcined 35 hours for 500 550 DEG C, i.e. obtains the Cu-SAPO-34 catalyst of auxiliary agent doping.

The Cu-SAPO-34 catalyst of a kind of auxiliary agent the most according to claim 1 doping, it is characterised in that the doping of preferred promoter is 2 10wt% of carrier quality, and auxiliary agent exists in the form of the oxide.

3. the preparation method of catalyst as claimed in claim 1, it is characterised in that be prepared as steps described below:

Preparation method the most according to claim 3, it is characterised in that in described step 1, by silicoaluminophosphamolecular molecular sieves and (NH with reactive hydrogen₄)₂SO₄Aqueous solution fully reacts at least 2h 70 80 DEG C of stirred in water bath, so that reactive hydrogen is by NH₄ ⁺Exchange.

Preparation method the most according to claim 3, it is characterised in that in described step 1, by silicoaluminophosphamolecular molecular sieves and (NH with reactive hydrogen₄)₂SO₄Aqueous solution fully reacts 2 8h 70 80 DEG C of stirred in water bath, so that reactive hydrogen is by NH₄ ⁺Exchange.

Preparation method the most according to claim 3, it is characterised in that in described step 1, will be by NH₄ ⁺Silicoaluminophosphamolecular molecular sieves after exchange and copper sulfate solution fully react at least 10h 70 80 DEG C of stirred in water bath.

Preparation method the most according to claim 3, it is characterised in that In described step 1, will be by NH₄ ⁺Silicoaluminophosphamolecular molecular sieves after exchange and copper sulfate solution fully react 12 24h 70 80 DEG C of stirred in water bath.

Preparation method the most according to claim 3, it is characterised in that in described step 2, stands at least 10h.

Preparation method the most according to claim 3, it is characterised in that in described step 2, stands 12 24h.

10. the application in selective catalysis of the catalyst as described in one of claim 12, it is characterised in that using 40-60 mesh catalyst, atmosphere is: 500ppm NO, 500ppmNH₃, 5%O₂, N₂For Balance Air；Total gas flow is 500ml/min, total empty time be 50000h^-1；Reaction temperature is 150～550 DEG C.

11. catalyst according to claim 10 application in selective catalysis, it is characterised in that described reaction temperature is 250 400 DEG C.