阅读说明：本技术 一种lta骨架结构的磷酸硅铝分子筛材料及其制备方法和应用 (Silicon-aluminum phosphate molecular sieve material with LTA framework structure and preparation method and application thereof ) 是由 曹磊 闫娜娜 马超 郭鹏 田鹏 刘中民 于 2019-09-24 设计创作，主要内容包括：本申请公开了一种具有LTA骨架结构的磷酸硅铝分子筛,所述分子筛的无水化学组成为：mR·(Si-xAl-yP-z)O-2；其中,R代表模板剂,m代表每摩尔(Si-xAl-yP-z)O-2对应模板剂R的摩尔数,m＝0.1～0.3；x、y、z分别表示Si、Al、P的摩尔分数,其范围分别是x＝0.01～0.40,y＝0.2～0.60,z＝0.2～0.60,且x+y+z＝1。采用该分子筛材料制备的负载金属的脱硝催化剂,能够在较宽温度范围内从诸如柴油机尾气中选择性脱除氮氧化物,并表现出较强的高温水热稳定性。(The application discloses a silicoaluminophosphate molecular sieve with LTA framework structure, the anhydrous chemistry composition of the molecular sieve is as follows: mR (Si) x Al y P z )O 2 (ii) a Wherein R represents a templating agent and m represents per mole (Si) x Al y P z )O 2 M is 0.1-0.3 corresponding to the mole number of the template agent R; x, y and z represent mole fractions of Si, Al and P, and the ranges of x is 0.01 to 0.40, y is 0.2 to 0.60, z is 0.2 to 0.60, and x + y + z is 1. Metal-loaded denitration catalyst prepared by adopting molecular sieve materialThe catalyst can selectively remove nitrogen oxides from tail gas of diesel engines in a wider temperature range and shows stronger high-temperature hydrothermal stability.)

1. A silicoaluminophosphate molecular sieve having an LTA framework structure, the molecular sieve having an anhydrous chemical composition as shown in formula I:

mR·(Si_xAl_yP_z)O₂formula I

Wherein R represents a templating agent;

m represents (Si) per mole_xAl_yP_z)O₂M is 0.1-0.3 corresponding to the mole number of the template agent R;

x, y and z represent mole fractions of Si, Al and P, and the ranges of x is 0.01 to 0.40, y is 0.2 to 0.60, z is 0.2 to 0.60, and x + y + z is 1.

2. The silicoaluminophosphate molecular sieve having an LTA framework structure of claim 1, wherein R in formula I is selected from at least one of ethylpropylamine, ethylisopropylamine, benzylisopropylamine, isopropylcyclohexylamine, 2- (isopropylamino) ethanol, 2- (butylamino) ethanol, 4-pyrrolidinopyridine.

3. A method of preparing a silicoaluminophosphate molecular sieve having an LTA framework structure as claimed in claim 1 or 2, comprising:

(1) uniformly mixing a mixture containing water, a silicon source, an aluminum source, a phosphorus source and a template agent R to obtain an initial gel mixture I;

(2) crystallizing the initial gel mixture I in the step (1) under a sealed condition to obtain the silicoaluminophosphate molecular sieve with the LTA framework structure.

4. The method of claim 3, wherein the molar ratio of water, silicon source, aluminum source, phosphorus source and templating agent R in the mixture of step (1) is:

SiO₂/Al₂O₃＝0.01～2.0；

P₂O₅/Al₂O₃＝0.2～3.0；

H₂O/Al₂O₃＝10～100；

R/H₂o is 0.01 to 0.1; r represents a template agent;

wherein the water is selected from H₂The silicon source is SiO in terms of mole number of O per se₂Based on the mole number of the aluminum source, the aluminum source is Al₂O₃In terms of moles of P as the phosphorus source₂O₅In moles of R, the templating agent R is in moles of R itself;

preferably, R/H₂O is 0.01 to 0.08; r represents a template agent;

preferably, a surfactant S is included in the mixture;

the molar ratio of the surfactant S to the aluminum source is as follows:

S/Al₂O₃0 to 1.0; s represents a surfactant;

wherein the aluminum source is Al₂O₃Based on the number of moles of S, surfactant S is based on the number of moles of S itself;

preferably, the molar ratio of the surfactant S to the aluminum source is:

S/Al₂O₃＝0～0.5；

further preferably, the molar ratio of the surfactant S to the aluminum source is:

S/Al₂O₃＝0～0.3；

preferably, the surfactant is selected from at least one of tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, dimethylhexadecyl [ 3-trimethylsilylpropyl ] ammonium chloride, dimethyloctadecyl [ 3-trimethylsilylpropyl ] ammonium chloride, hexadecyltrimethoxysilane.

5. The method according to claim 3, wherein the silicon source is at least one selected from the group consisting of silica white, silica sol, silica gel, water glass, active silica, and orthosilicate;

the aluminum source is selected from at least one of aluminum salt, aluminate, activated alumina, alkoxy aluminum, pseudo boehmite and pseudo boehmite;

the phosphorus source is at least one of orthophosphoric acid, phosphate, organic phosphide and phosphorus oxide;

the template agent is selected from at least one of ethylpropylamine, ethylisopropylamine, benzylisopropylamine, isopropylcyclohexylamine, 2- (isopropylamino) ethanol, 2- (butylamino) ethanol and 4-pyrrolidinyl pyridine.

6. The method according to claim 3, wherein the crystallization conditions in step (2) are:

the crystallization temperature is 150-250 ℃;

the crystallization time is not less than 1 hour;

preferably, the crystallization temperature is 180-220 ℃;

preferably, the crystallization time is not less than 8 hours;

further preferably, the crystallization time is 18 to 72 hours.

7. The method according to claim 3, wherein a seed crystal is added before the crystallization in the step (2);

the seed crystal is an LTA-SAPO molecular sieve;

preferably, the seed crystal addition amount is Al₂O₃0-20% of the mass;

preferably, the seed crystal addition amount is Al₂O₃0 to 10% by mass.

8. A method according to claim 3, characterized in that the method comprises the steps of:

a) uniformly mixing water, a silicon source, an aluminum source, a phosphorus source, a surfactant S and a template R to obtain an initial gel mixture I;

the molar ratio of water, a silicon source, an aluminum source, a phosphorus source, a surfactant S and a template R in the mixture is as follows:

SiO₂/Al₂O₃＝0.01～2.0；

P₂O₅/Al₂O₃＝0.2～3.0；

H₂O/Al₂O₃＝10～100；

S/Al₂O₃0 to 1.0; s represents a surfactant;

R/H₂o is 0.01 to 0.08; r represents a template agent;

wherein the water is selected from H₂The silicon source is SiO in terms of mole number of O per se₂Based on the mole number of the aluminum source, the aluminum source is Al₂O₃Surfactant S in moles of S itself, templating agent R in moles of R itself;

b) filling the initial gel mixture I into a synthesis kettle, sealing, and crystallizing under a rotating condition; the crystallization temperature is 150-250 ℃, and the crystallization time is not less than 8 hours;

c) and after crystallization is finished, separating a solid product to obtain the silicoaluminophosphate molecular sieve with the LTA framework structure.

9. A denitration catalyst, characterized by comprising at least the steps of: putting the molecular sieve raw powder into a solution containing metal ions for ion exchange, and after the ion exchange is finished, washing, drying and roasting the obtained solid to obtain the metal-loaded denitration catalyst;

wherein the molecular sieve raw powder is at least one selected from the group consisting of the silicoaluminophosphate molecular sieve having an LTA framework structure as defined in claim 1 or 2, and the silicoaluminophosphate molecular sieve having an LTA framework structure prepared by the method as defined in any one of claims 3 to 8.

10. The catalyst according to claim 9, wherein the metal ion is at least one selected from the group consisting of copper ion, iron ion, cerium ion, nickel ion, manganese ion, and strontium ion;

preferably, the copper ion is Cu⁺And/or Cu²⁺The iron ion is Fe²⁺And/or Fe³⁺The cerium ion is Ce³⁺And/or Ce⁴⁺；

Preferably, the metal ions account for 1-7% of the weight of the molecular sieve raw powder;

preferably, the metal ions account for 3.1-7% of the weight of the molecular sieve raw powder;

preferably, the denitration catalyst loaded with metal is obtained by washing, drying and roasting the solid obtained after ion exchange at the temperature of not less than 600 ℃.

Technical Field

The application relates to a silicoaluminophosphate molecular sieve material with an LTA framework structure, a preparation method thereof and a metal-loaded denitration catalyst prepared from the molecular sieve material, belonging to the field of materials.

Background

In the fields of diesel engine tail gas denitration and the like, a metal-loaded silicon aluminum (Cu/SSZ-13) or silicon aluminum phosphate molecular sieve (Cu/SAPO-34) with a CHA topological structure is generally adopted as a catalyst in recent years. Wherein, metal ions are incorporated into the molecular sieve framework through a traditional ion exchange mode or a one-step synthesis method and play a role of an active center. The smaller pore structure in the molecular sieve framework can inhibit the problems of dealumination, hydrocarbon poisoning and the like in the long-term use process, and the performance characteristics of the catalyst are known in the field. However, in the foreseeable future, with the upgrading of emission standards, the low temperature activity of denitration catalysts and their good hydrothermal stability at high temperatures are important for the future development, for further reducing the pollutant emissions during the cold start of engines, and for frequent regeneration processes that have to be taken to ensure higher PM emission requirements. However, the Cu/SSZ-13 type catalyst currently used in the industry has short plates with different degrees of low-temperature activity and high-temperature hydrothermal stability, and there is a certain degree of compromise in selecting the Cu/SSZ-13 type catalyst as a technical route which currently meets the six national emission standards.

In 1982, United states Union carbide (UCC) developed a series of products consisting of PO₂ ⁺And AlO₂ ^-An AlPO molecular sieve with regular pore channels or cage-like structure formed by connecting tetrahedrons at the same vertex (J.Am.chem.Soc.,1982,4, 1146-1147). Subsequently, in 1984, Si atoms isomorphously substituted P and Al, another series of silicoaluminophosphate molecular sieves SAPO (J.Am.chem.Soc.,1982,4,1146-1147) were synthesized. Due to SAPO molecules after calcinationThe sieve has protonic acid sites, so that the SAPO molecular sieve has practical application value in industrial catalysis, gas adsorption separation and the like. Among the molecular sieves, the Cu/SAPO-34 type small-pore molecular sieve catalyst which also takes CHA as a topological structure shows excellent denitration catalytic performance. However, this type of catalyst suffers from a compromise between low temperature activity and high temperature hydrothermal stability, limited by the ion exchange conditions, and it is difficult to achieve an optimum balance of properties in combination. Therefore, based on the high-temperature hydrothermal stability of the silicoaluminophosphate and the dealumination resistance and hydrocarbon poisoning resistance of the small-pore molecular sieve, the development of other types of small-pore silicoaluminophosphate type denitration catalysts has stronger application background and necessity.

The LTA molecular sieve topological structure is formed by connecting beta cages through double four-membered rings (can also be described as alpha cages through eight-membered rings), belongs to a cubic crystal system, and has a three-dimensional eight-membered ring channel with the pore size of 0.41nm multiplied by 0.41 nm. The characteristics make the denitration catalyst material hopeful to have application prospect. In 1984, the United states Union carbide (UCC) company reported tetramethylammonium and Na for the first time⁺SAPO molecular sieves with LTA structures were synthesized (J.Am.chem.Soc.,1982,4, 1146-1147). LTA-SAPO in the prior art has low silicon content, expensive template, easy synthesis in a fluorine-containing system, easy corrosion of equipment and danger (Microporous MeOoporus Mat.,2014,200, 132-.

Therefore, the development of an LTA-SAPO synthesis method with low cost, low pollution and controllable composition and a denitration catalyst prepared based on the material are one of the optional paths for breaking through the limitation of the existing material and meeting the development of the future emission standard.

Disclosure of Invention

According to one aspect of the present application, a silicoaluminophosphate molecular sieve having an LTA framework structure is provided, which LTA-SAPO molecular sieve can be used as NH via copper exchange₃-SCR reaction catalyst and has a high reactivity.

The silicoaluminophosphate molecular sieve with the LTA framework structure is characterized in that the anhydrous chemical composition of the molecular sieve is shown as a formula I:

mR·(Si_xAl_yP_z)O₂formula I

Wherein R represents a templating agent;

m represents (Si) per mole_xAl_yP_z)O₂M is 0.1-0.3 corresponding to the mole number of the template agent R;

x, y and z represent mole fractions of Si, Al and P, and the ranges of x is 0.01 to 0.40, y is 0.2 to 0.60, z is 0.2 to 0.60, and x + y + z is 1.

Optionally, R in formula I is selected from at least one of ethylpropylamine, ethylisopropylamine, benzylisopropylamine, isopropylcyclohexylamine, 2- (isopropylamino) ethanol, 2- (butylamino) ethanol, and 4-pyrrolidinyl-pyridine.

Alternatively, the upper limit of x in formula I is selected from 0.164, 0.168, 0.298, 0.316, 0.336, or 0.40; the lower limit is selected from 0.01, 0.164, 0.168, 0.298, 0.316 or 0.336.

Optionally, the size of the silicoaluminophosphate molecular sieve with the LTA framework structure is 200nm to 20 μm.

In another aspect of the present application, there is provided a method for preparing the silicoaluminophosphate molecular sieve having the LTA framework structure, which comprises:

(1) uniformly mixing a mixture containing water, a silicon source, an aluminum source, a phosphorus source and a template agent R to obtain an initial gel mixture I;

(2) crystallizing the initial gel mixture I in the step (1) under a sealed condition to obtain the silicoaluminophosphate molecular sieve with the LTA framework structure.

The method can simply and efficiently use ethylpropylamine, ethylisopropylamine, benzylisopropylamine, isopropylcyclohexylamine, 2- (isopropylamino) ethanol, 2- (butylamino) ethanol or 4-pyrrolidinylpyridine as a template agent to obtain the pure-phase LTA-SAPO molecular sieve.

Optionally, the molar ratio of water, a silicon source, an aluminum source, a phosphorus source and the template agent R in the mixture in the step (1) is:

SiO₂/Al₂O₃＝0.01～2.0；

P₂O₅/Al₂O₃＝0.2～3.0；

H₂O/Al₂O₃＝10～100；

R/H₂o is 0.01 to 0.1; r represents a template agent;

wherein the water is selected from H₂The silicon source is SiO in terms of mole number of O per se₂Based on the mole number of the aluminum source, the aluminum source is Al₂O₃In terms of moles of P as the phosphorus source₂O₅Based on the moles of R, the templating agent R is based on the moles of R itself.

Alternatively, R/H₂O is 0.01 to 0.08; r represents a template agent.

Optionally, in step (1), the mixture is mixed uniformly by stirring.

Optionally, a surfactant S is included in the mixture in step (1);

the molar ratio of the surfactant S to the aluminum source is as follows:

S/Al₂O₃0 to 1.0; s represents a surfactant;

wherein the aluminum source is Al₂O₃Based on the number of moles of S, the surfactant S is based on the number of moles of S itself.

Optionally, the molar ratio of the surfactant S to the aluminum source is:

S/Al₂O₃＝0～0.5。

optionally, the molar ratio of the surfactant S to the aluminum source is:

S/Al₂O₃＝0～0.3。

alternatively, the surfactant S may be used in the amount of 0 in step (1), and may be selectively added within the above range.

Alternatively, SiO₂/Al₂O₃Is selected from 0.02, 0.05, 0.1, 0.15, 0.175, 0.2, 0.25, 0.3, 0.35, 0.375, 0.4, 0.45, 0.5, 1.0, 1.2, 1.5 or 2.0; the lower limit is selected from 0.01, 0.02, 0.05, 0.1, 0.15, 0.175, 0.2, 0.25, 0.3, 0.35, 0.375, 0.4, 0.45, 0.5, 1.0, 1.2 or 1.5.

Alternatively,P₂O₅/Al₂O₃the upper limit of the molar ratio of (a) is selected from 0.3, 0.5, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 2.8 or 3.0; the lower limit is selected from 0.2, 0.3, 0.5, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5 or 2.8.

Alternatively, H₂O/Al₂O₃Is selected from 15, 20, 30, 40, 50, 60, 70, 80, 90 or 100; the lower limit is selected from 10, 15, 20, 30, 40, 50, 60, 70, 80 or 90.

Alternatively, R/H₂The upper limit of the molar ratio of O is selected from 0.02, 0.025, 0.035, 0.04, 0.044, 0.045, 0.05, 0.055, 0.06, 0.08 or 0.1; the lower limit is selected from 0.01, 0.02, 0.025, 0.035, 0.04, 0.044, 0.045, 0.05, 0.055, 0.06, or 0.08.

Alternatively, S/Al₂O₃Is selected from 0.002, 0.005, 0.01, 0.02, 0.05, 0.075, 0.10, 0.15, 0.20, 0.30, 0.40, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.0; the lower limit is selected from 0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.075, 0.10, 0.15, 0.20, 0.30, 0.40, 0.5, 0.6, 0.7, 0.8 or 0.9.

Optionally, the surfactant is selected from at least one of tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, dimethylhexadecyl [ 3-trimethylsilylpropyl ] ammonium chloride, dimethyloctadecyl [ 3-trimethylsilylpropyl ] ammonium chloride, hexadecyltrimethoxysilane.

Optionally, the surfactant is at least one of octadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, and hexadecyl trimethyl ammonium bromide.

Optionally, the silicon source is selected from at least one of white carbon black, silica sol, silica gel, water glass, active silica and orthosilicate;

the aluminum source is selected from at least one of aluminum salt, aluminate, activated alumina, alkoxy aluminum, pseudo boehmite and pseudo boehmite;

the phosphorus source is at least one of orthophosphoric acid, phosphate, organic phosphide and phosphorus oxide;

the template agent is selected from at least one of ethylpropylamine, ethylisopropylamine, benzylisopropylamine, isopropylcyclohexylamine, 2- (isopropylamino) ethanol, 2- (butylamino) ethanol and 4-pyrrolidinyl pyridine.

Optionally, the silicon source is selected from at least one of tetraethoxysilane, white carbon black and silica sol.

Optionally, the aluminum source is at least one of pseudoboehmite and aluminum isopropoxide.

Optionally, the phosphorus source is orthophosphoric acid.

Optionally, the aluminum alkoxide comprises aluminum isopropoxide.

Optionally, the crystallization condition is rotational crystallization.

Optionally, the crystallization conditions in step (2) are:

the crystallization temperature is 150-250 ℃;

the crystallization time is not less than 1 hour.

Optionally, the crystallization temperature is 180-220 ℃.

Optionally, the crystallization time is not less than 8 hours.

Optionally, the crystallization time is 18-72 hours.

Optionally, the upper temperature limit for crystallization is selected from 160 ℃, 170 ℃, 180 ℃, 190 ℃,200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃; the lower limit is selected from 150 deg.C, 160 deg.C, 170 deg.C, 180 deg.C, 190 deg.C, 200 deg.C, 210 deg.C, 220 deg.C, 230 deg.C, and 240 deg.C.

Optionally, the upper time limit for crystallization is selected from 18 hours, 24 hours, 26 hours, 30 hours, 48 hours, 64 hours, or 72 hours; the lower limit is selected from 8 hours, 10 hours, 12 hours, 16 hours, 18 hours, 24 hours, 26 hours, 30 hours, 48 hours, or 64 hours.

Optionally, a seed crystal is added before the crystallization in the step (2);

the seed crystal is LTA-SAPO molecular sieve.

Optionally, the seed crystal is LTA-SAPO molecular sieve obtained by air roasting at 600 ℃.

Optionally, the addition amount of the seed crystal is Al₂O₃0 to 20% by mass.

Optionally, the addition amount of the seed crystal is Al₂O₃0 to 10% by mass.

Alternatively, the addition amount of the seed crystal may be 0, and may be selectively added within the above range.

Optionally, the addition amount of the seed crystal is Al₂O₃The upper limit of the mass fraction is selected from 1%, 2%, 5%, 10%, 15% or 20%; the lower limit is selected from 0, 1%, 2%, 5%, 10% or 15%.

As a specific embodiment, the method comprises the steps of:

a) uniformly mixing water, a silicon source, an aluminum source, a phosphorus source, a surfactant S and a template R to obtain an initial gel mixture I;

the molar ratio of water, a silicon source, an aluminum source, a phosphorus source, a surfactant S and a template R in the mixture is as follows:

SiO₂/Al₂O₃＝0.01～2.0；

P₂O₅/Al₂O₃＝0.2～3.0；

H₂O/Al₂O₃＝10～100；

S/Al₂O₃0 to 1.0; s represents a surfactant;

R/H₂o is 0.01 to 0.08; r represents a template agent;

wherein the water is selected from H₂The silicon source is SiO in terms of mole number of O per se₂Based on the mole number of the aluminum source, the aluminum source is Al₂O₃Surfactant S in moles of S itself, templating agent R in moles of R itself;

b) filling the initial gel mixture I into a synthesis kettle, sealing, and crystallizing under a rotating condition; the crystallization temperature is 150-250 ℃, and the crystallization time is not less than 8 hours;

c) and after crystallization is finished, separating a solid product to obtain the silicoaluminophosphate molecular sieve with the LTA framework structure.

In another aspect of the application, a denitration reaction catalyst is provided, which is characterized in that molecular sieve raw powder is placed in a solution containing metal ions for ion exchange, and after the ion exchange is finished, the obtained solid is obtained by washing, drying and roasting;

wherein the molecular sieve raw powder is at least one selected from the silicoaluminophosphate molecular sieve with the LTA framework structure and the silicoaluminophosphate molecular sieve with the LTA framework structure prepared by any one of the methods.

In the selection of the metal ion exchange method, the direct method ion exchange described in patent CN105984876B can be performed on the premise of retaining the template agent, so as to ensure the framework integrity of the SAPO molecular sieve to the greatest extent. Therefore, the ion exchange of the metal salt solution of the present application is preferably performed by the above-mentioned method.

Alternatively, the metal ions may be exchanged by one of conventional liquid phase ion exchange and solid phase ion exchange.

Optionally, the metal ion is selected from at least one of copper ion, iron ion, cerium ion, nickel ion, manganese ion, strontium ion, platinum ion, palladium ion, rhodium ion, magnesium ion, or a combination thereof.

Alternatively, the metal ion includes multiple valences, e.g., the copper ion is Cu⁺And/or Cu²⁺The iron ion is Fe²⁺And/or Fe³⁺，Ce³⁺And/or Ce⁴⁺And the like.

Alternatively, the metal ions comprise 1-7% by weight of the silicoaluminophosphate molecular sieve.

Alternatively, the metal ions comprise from 3.1 to 7% by weight of the silicoaluminophosphate molecular sieve.

Optionally, washing, drying and roasting the solid obtained after ion exchange at the temperature of not less than 600 ℃ to obtain the metal-loaded denitration catalyst.

Optionally, the exchanged and washed metal-containing molecular sieve powder is dried at a temperature of not higher than 120 ℃ for more than 12 hours.

Optionally, the dried metal-containing molecular sieve powder is roasted at a temperature of 600-800 ℃ for more than 2 hours to form the final metal-loaded denitration catalyst.

All conditions in this application that relate to a numerical range can be independently selected from any point within the numerical range.

In this application, the term "static crystallization" means that during crystallization, the vessel containing the initial gel mixture is left in an oven without stirring the mixture in the synthesis vessel.

In the present application, the term "rotary crystallization" refers to the synthesis vessel containing the initial gel mixture being in a non-stationary state, such as being turned, rotated, etc., during crystallization; or in the crystallization process, stirring the mixture in the synthesis kettle.

In this application, the denitration reaction catalyst effect evaluation conditions are: space velocity of 300000 h^-1，NO 500ppm、NH₃500ppm、H₂O 4.5％、O₂14% and nitrogen balance. The conditions for evaluating the high-temperature hydrothermal stability are as follows: 800 ℃ and H₂O10%, 16 hours.

The beneficial effects that this application can produce include:

1) the LTA-SAPO molecular sieve synthesized by different templates is obtained, and the molecular sieve has high purity and high silicon content.

2) The preparation method provided by the application is simple in process and is synthesized under the fluorine-free condition.

3) The preparation method provided by the application has the advantages that the template agent is cheap, the surfactant can be selectively added, and the synthesis cost is low.

4) The metal-loaded denitration catalyst provided by the application has excellent high-temperature catalytic activity and high-temperature hydrothermal stability.

Drawings

FIG. 1 is an X-ray powder diffraction pattern (XRD) of sample 1 obtained in example 1 of the present invention.

FIG. 2 is a Scanning Electron Micrograph (SEM) of sample 1 obtained in example 1 of the present invention.

FIG. 3 is a nuclear magnetic carbon spectrum of sample 1 obtained in example 1 of the present invention (¹³C MAS NMR)。

FIG. 4 is a graph showing the activity of a Cu/SAPO type denitration catalyst in example 1 of the present invention, wherein ■ is the initial activity of the catalyst, and ● is the activity of the catalyst after hydrothermal aging at 80 ℃ for 16 hours.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.

The analysis method in the examples of the present application is as follows:

the sample phase analysis was performed by X-ray powder diffraction (XRD) analysis using an X' Pert PRO X-ray diffractometer from Panaxacaceae (PANALYTICAL) in the Netherlands, using a Cu target, a Kalpha light sourceThe test is carried out under the conditions of 40KV voltage and 40mA current.

The sample composition was analyzed by X-ray fluorescence spectroscopy (XRF) and determined on a Magix-601 model X-ray fluorescence spectrometer from Philips.

Sample morphology analysis by Scanning Electron Microscope (SEM) using the instrument: TM 3000.

A TA Q-600 thermal analyzer was used to thermally analyze the samples from room temperature to 900 ℃ at a temperature ramp rate of 10 ℃/min.

Carbon nuclear magnetic resonance (¹³C MAS NMR) analysis using an Avance III600WB solid nuclear magnetic spectrometer from brueck corporation, operating at a magnetic field strength of 14.1T.

Example 1 preparation of sample 1 and catalyst 1

1.010g of aluminum isopropoxide (99%), 0.452g of orthophosphoric acid (85%), and 0.364g of ethyl orthosilicate (96%) are mixed and stirred uniformly in 4.318g of deionized water, then 1.293g of ethylpropylamine (99%) is added under stirring, 0.178g of hexadecyltrimethylammonium bromide (99%) is dissolved and then added into the gel system, and the mixture is stirred and mixed uniformly vigorously (rotating speed: 500r/min) to obtain a mixture I. Moving the mixture I toAnd (3) rotating and crystallizing the mixture for 26 hours at 200 ℃ in a stainless steel high-pressure reaction kettle under the autogenous pressure, centrifuging and washing a solid product after crystallization is finished, and drying the solid product in air at 100 ℃ to obtain the LTA-SAPO molecular sieve which is recorded as a sample 1. The X-ray powder diffraction pattern (XRD) of sample 1 is shown in fig. 1, indicating that sample 1 is a silicoaluminophosphate molecular sieve having an LTA framework structure. Scanning Electron Micrographs (SEM) as shown in fig. 2, the particles of sample 1 were cubic and relatively smooth at the edges, with a size of about 15 μm. XRF analysis and thermal analysis normalization gave sample 1 with an elemental composition of: 0.161R. (Si)_0.164Al_0.472P_0.364)O₂(ii) a Wherein R is ethyl propylamine. Of sample 1¹³The result of the C MAS NMR spectrum shown in FIG. 3 shows that the structural integrity of the template ethyl propylamine in the molecular sieve and the synthesized sample does not contain the surfactant cetyl trimethyl ammonium bromide.

The mixture was exchanged for 4 hours at 80 ℃ with stirring by passing a copper acetate solution (concentration: 0.1mol/L) at a liquid-solid mass ratio of 40. Then washing with deionized water, and filtering until the conductivity of the filtrate is less than 200 muS/cm. The obtained powder was dried at 120 ℃ for 12 hours and calcined at 600 ℃ for 2 hours to obtain a Cu/SAPO type denitration catalyst, which was designated as catalyst 1. The resulting catalyst had a Cu weight of 5.9% as determined by XRF fluorescence spectroscopy.

Tabletting and granulating the obtained catalyst 1 to obtain catalyst particles with the particle size of 60-80 meshes, doping isometric quartz sand, and placing the catalyst particles in a quartz tube fixed bed reactor for initial performance evaluation. After the initial activity evaluation, the catalyst was subjected to 16-hour high-temperature hydrothermal aging, and then performance testing was performed again. FIG. 4 is a graph showing the initial activity of catalyst 1 and the activity after hydrothermal aging at high temperature, wherein ■ is the initial activity of the catalyst, and ● is the activity of the catalyst after hydrothermal aging at 80 ℃ for 16 hours. The catalyst exhibits very good initial activity, especially at temperatures above 250 ℃ the NO conversion remains at 100% at all times. After the hydrothermal aging at the extreme high temperature of 800 ℃ for 16 hours, the activity of the catalyst does not decrease and increases reversely, and the activity of the high-temperature section of the catalyst is well maintained.

Example 2 preparation of sample 2 and catalyst 2

The procedure is as in example 1 except that cetyltrimethylammonium bromide, a surfactant, was not added in this example. The resulting LTA-SAPO molecular sieve, denoted as sample 2. And (3) taking the obtained sample 2 for XRD diffraction analysis, wherein the spectrogram is similar to that of the sample 1, and the sample synthesized by the method is the molecular sieve with the LTA structure. Sample 2 a Scanning Electron Micrograph (SEM) is similar to sample 1. Of sample 2¹³The C MAS NMR spectrum was similar to that of sample 1, indicating the structural integrity of the templating agent, ethylpropylamine, in the molecular sieve.

In the same manner as in example 1, a catalyst sample having a Cu content of 5.7% by weight was finally obtained after copper acetate ion exchange, washing, drying and calcination and was designated as catalyst 2. And tabletting and granulating the obtained catalyst 2 to obtain catalyst particles with the particle size of 60-80 meshes, doping isovolumetric quartz sand, and placing the catalyst particles in a quartz tube fixed bed reactor for initial performance evaluation. After the initial activity evaluation, the catalyst was subjected to 16-hour high-temperature hydrothermal aging, and then performance testing was performed again.

Examples 3-4 preparation of catalysts 3-4

The molecular sieve synthesis was performed as in example 1. The catalyst synthesis was carried out by stirring and exchanging for 4 hours at 80 ℃ with a copper acetate solution (concentration of 0.5mol/L) at a liquid-solid mass ratio of 40. And then washing by using deionized water, filtering until the conductivity of the filtrate is less than 200 mu S/cm, drying the obtained powder at 120 ℃ for 12 hours, and roasting at 600 ℃ for 2 hours to obtain the Cu/SAPO type denitration catalyst, which is recorded as catalyst 3. The resulting catalyst had a Cu weight of 3.1% as determined by XRF fluorescence spectroscopy. The same exchange conditions were used and the cupric acetate ion exchange was repeated until a catalyst weight of 7.0% Cu was obtained, which was designated catalyst 4.

Example 5 preparation of catalyst 5

The molecular sieve synthesis was performed as in example 1. The difference of catalyst synthesis is that firstly cerium nitrate solution (with the concentration of 0.1mol/L) is adopted, the liquid-solid mass ratio is 40, and the mixture is stirred and exchanged for 4 hours at the temperature of 80 ℃. Then washing with deionized water, filtering, and standingThe resulting powder was dried at 120 ℃ for 12 hours until the filtrate conductivity was less than 200. mu.S/cm. Then, a copper acetate solution (with a concentration of 0.1mol/L) was used in a liquid-solid mass ratio of 40, and the mixture was stirred at 80 ℃ for 4 hours of exchange. And then washing by using deionized water, filtering until the conductivity of the filtrate is less than 200 mu S/cm, drying the obtained powder at 120 ℃ for 12 hours, and roasting at 600 ℃ for 2 hours to obtain the CuCe/SAPO type denitration catalyst, which is marked as catalyst 5. The resulting catalyst had a Cu content of 5.1% by weight, CeO, as determined by XRF fluorescence spectroscopy₂The weight was 1.2%.

Examples 6-17 preparation of samples 3-14

The glue blending process of samples 3-14 was the same as in example 1, and the selection of the specific silicon source, aluminum source and phosphorus source, the blending ratio and the crystallization conditions during the blending are shown in table 1. The XRD spectrogram and SEM image of samples 3-14 are similar to those of sample 1, and the silicoaluminophosphate molecular sieve with LTA framework structure is obtained, and the size is 200 nm-20 mu m.

Samples 3-14 prepared in examples 6-17, which were LTA-SAPO samples, were normalized by XRF analysis and thermal analysis to obtain elemental compositions with anhydrous chemical compositions mR (Si)_xAl_yP_z)O₂Wherein m, x, y and z are all in the range of 0.12-0.2, 0.05-0.4, 0.35-0.5, 0.25-0.5 and 1. Samples 3 to 14 were carried out¹³C MAS NMR nuclear magnetic resonance characterization shows that the results all indicate the structural integrity of the template in the molecular sieve.

TABLE 1 table of raw material types, compounding ratios, and crystallization conditions of examples 6 to 17

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.