阅读说明：本技术 镁磷铝组成的afn结构杂原子分子筛及其合成方法和应用 (AFN structure heteroatom molecular sieve composed of magnesium, phosphorus and aluminum, and synthetic method and application thereof ) 是由 梁世航 赵晨 王永睿 慕旭宏 于 2019-09-24 设计创作，主要内容包括：本发明涉及催化材料合成领域,具体公开一种镁磷铝组成的AFN结构杂原子分子筛及其合成方法和应用。本发明所述AFN结构杂原子分子筛的杂原子为Mg。本发明以异丙胺作为模板剂,采用磷铝干胶液相转化法首次合成出一种骨架元素为镁磷铝组成的AFN结构杂原子分子筛。所述AFN结构镁磷铝杂原子分子筛在气体吸附分离领域中具有良好的应用前景。(The invention relates to the field of catalytic material synthesis, and particularly discloses an AFN structure heteroatom molecular sieve composed of magnesium, phosphorus and aluminum, and a synthesis method and application thereof. The heteroatom of the heteroatom molecular sieve with the AFN structure is Mg. The invention uses isopropylamine as a template agent and adopts a phosphorus-aluminum dry glue solution phase conversion method to synthesize the AFN structure heteroatom molecular sieve with the framework element formed by magnesium, phosphorus and aluminum for the first time. The magnesium-phosphorus-aluminum heteroatom molecular sieve with the AFN structure has a good application prospect in the field of gas adsorption and separation.)

1. The AFN structure heteroatom molecular sieve is characterized in that the heteroatom of the AFN structure heteroatom molecular sieve is Mg.

2. The molecular sieve of claim 1, wherein the AFN-structured heteroatom molecular sieve raw powder XRD pattern consisting of magnesium, phosphorus and aluminum at least contains diffraction peaks as shown in the following table 1;

TABLE 1

2θ(deg) Relative intensity (100 × I/I)₀) 8.974 100.00 9.460 10.56 11.141 22.10 13.097 22.84 13.347 11.64 15.842 15.03 15.933 15.39 17.956 11.85 21.776 11.75 22.236 12.45 22.643 21.16

The table above lists essentially XRD diffraction peak data for relative intensities of 100 × I/I0> 10.

3. A synthesis method of an AFN structure heteroatom molecular sieve composed of magnesium, phosphorus and aluminum is characterized by comprising the following steps:

providing an initial gel mixture containing a dry aluminum phosphate gel, a magnesium source, a templating agent, and water;

crystallizing the initial gel mixture;

carrying out solid-liquid separation on the crystallized product, and washing, drying and optionally roasting the obtained solid phase;

wherein the template agent is isopropylamine.

4. The synthesis method according to claim 3, wherein the preparation method of the phosphorus aluminum dry glue comprises the following steps:

and (3) aging a mixture containing a phosphorus source, an aluminum source and water, and then drying to obtain the phosphorus-aluminum dry glue.

5. The synthetic method according to claim 4, wherein,

the phosphorus source is P₂O₅The aluminum source is calculated as Al₂O₃The molar ratio of the phosphorus source, the aluminum source and the water in the mixture is 0.6-1.2:1:30-70, preferably 0.8-1.2:1: 35-65.

6. The synthesis process according to claim 4, wherein the mixture is aged under stirring at a temperature of 50-80 ℃, preferably 60-70 ℃, for a time of 6-20 hours, preferably 10-18 hours; the drying temperature is 80-110 deg.C, preferably 80-100 deg.C, and the drying time is 15-35 hr, preferably 20-30 hr.

7. A synthesis method according to any one of claims 3 to 6, wherein the phosphorus aluminium dry glue is coated with Al₂O₃The magnesium source is calculated by MgO, and the molar ratio of the phosphorus-aluminum dry glue, the magnesium source, the template agent and the water in the initial gel mixture is 1:0.01-0.6:1-3:10-200, preferably 1:0.1-0.5:1.5-3: 20-120.

8. The synthesis method according to any one of claims 3 to 7, wherein the crystallization is a two-stage crystallization process comprising a first stage crystallization and a second stage crystallization, and the first stage crystallization temperature is lower than the second stage crystallization temperature;

the first section of crystallization is carried out for 25 to 45 hours under the autogenous pressure and the temperature of 130-170 ℃, and the second section of crystallization is carried out for 30 to 55 hours under the autogenous pressure and the temperature of 170-200 ℃;

preferably, the first-stage crystallization is performed at the autogenous pressure and the temperature of 140-165 ℃ for 25-40 hours, and the second-stage crystallization is performed at the autogenous pressure and the temperature of 170-195 ℃ for 35-50 hours;

more preferably, the first-stage crystallization is performed at the autogenous pressure and the temperature of 140-160 ℃ for 30-40 hours, and the second-stage crystallization is performed at the autogenous pressure and the temperature of 175-190 ℃ for 40-50 hours.

9. The synthesis method according to any one of claims 3 to 7, wherein the crystallization is a single-stage crystallization process, and the crystallization is performed under autogenous pressure at 170 ℃ and 210 ℃ for 30 to 92 hours; preferably, the crystallization is carried out for 40-85 hours under the autogenous pressure and at the temperature of 170-200 ℃; more preferably, the crystallization is carried out under autogenous pressure at 190 ℃ for 50-80 hours.

10. The synthesis method according to any one of claims 3 to 7, wherein the phosphorus source is selected from at least one of orthophosphoric acid, phosphorous acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate and an organic phosphide; the organic phosphide is preferably trimethyl phosphorus and/or triethyl phosphorus.

11. The synthesis method according to any one of claims 3 to 7, wherein the aluminum source is selected from at least one of aluminum salt, pseudoboehmite, aluminum isopropoxide, aluminum hydroxide dry gel and activated alumina; the aluminium salt is preferably aluminium chloride and/or aluminium sulphate.

12. A synthesis method according to any one of claims 3 to 7, wherein the magnesium source is selected from at least one of magnesium acetate tetrahydrate, magnesium nitrate hexahydrate and magnesium phosphate octahydrate, preferably magnesium acetate tetrahydrate.

13. The synthesis method according to any one of claims 3 to 7, wherein the temperature for drying the obtained solid phase is 90 to 120 ℃ and the temperature for calcining is 400-700 ℃.

14. Use of an AFN-structured heteroatomic molecular sieve composed of magnesium, phosphorus and aluminum according to claim 1 or 2 or obtained by the synthesis method according to any one of claims 3 to 13 in gas adsorption separation.

Technical Field

The invention relates to the field of catalytic material synthesis, in particular to an AFN structure heteroatom molecular sieve composed of magnesium, phosphorus and aluminum, a synthesis method thereof and application of the AFN structure heteroatom molecular sieve composed of magnesium, phosphorus and aluminum.

Background

The phosphorus-aluminum molecular sieve is an important porous material which is widely applied to the fields of adsorption, separation, catalysis, ion exchange and the like. In 1982, united states carbide corporation (UCC) first developed a series of aluminophosphate molecular sieves, AlPO₄-n (n stands for structural model). Then, researchers successfully synthesize more than 60 kinds of phosphorus-aluminum molecular sieves with different structure types by using organic matters of different systems as templates or structure directing agents by using a hydrothermal synthesis method, a solvothermal synthesis method, a xerogel synthesis method and the like. The typical phosphorus-aluminum molecular sieve has neutral skeleton and P/Al ratio of 1, and is made of PO₄Tetrahedron and AlO₄The tetrahedra are formed by strictly alternating arrangement of oxygen bridges. Later, some metal elements and non-metal elements are introduced into a phosphorus-aluminum molecular sieve framework to partially replace P and Al in the framework to form a heteroatom phosphorus-aluminum molecular sieve (such as MeAPO-n and SAPO-n), so that the framework composition is enriched, the structure type of the molecular sieve is expanded, and the application of the aluminum phosphate molecular sieve in the aspects of catalysis, magnetism, electricity, optics and the like is expanded.

AlPO-14 molecular sieves were an important aluminophosphate molecular sieve developed by UCC corporation in 1982 and assigned the structure code AFN by the International molecular sieves Association (IZA). The chemical formula is Al₈P₈O₃₂Belonging to the triclinic system, the space group isP-1, cell parameters of77.81 deg., 77.50 deg., 87.69 deg., and has three-dimensional eight-membered ring channel structure along [ 100%]Eight-membered ring pore size in the direction of 0.19X 0.46nm along [ 010%]Pore size of eight-membered ring in the direction of 0.21X 0.49nm along [001 ]]The aperture of the eight-membered ring is 0.33 multiplied by 0.40nm, belonging to the small-pore molecular sieve.

In 1982, USP4310440 disclosed two methods for synthesizing AlPO-14 for the first time. The first method is crystallization at 150 deg.c for 96 hr under hydrothermal condition, phosphoric acid as phosphorus source, pseudoboehmite as aluminum source and tert-butylamine (t-BuNH)₂) As a template agent, the synthesis process is carried out according to the proportion of 1.0t-BuNH₂:Al₂O₃:P₂O₅:40H₂The molar ratio of O. The second method is crystallization at 200 ℃ for 24 hours under hydrothermal condition, phosphoric acid is adopted as phosphorus source, hydrated alumina is adopted as aluminum source, isopropylamine (iPrNH) is adopted₂) As template agent, the synthesis process is according to 1.0iPrNH₂:Al₂O₃:P₂O₅:40H₂The molar ratio of O.

In 1986, the literature (Actacrystallographica,1986, C42, 670-. The molecular sieve is synthesized and crystallized for 86 hours at 200 ℃ under the hydrothermal condition, phosphoric acid is used as a phosphorus source, a gallium-containing compound is used as a gallium source, and isopropylamine (iPrNH) is used₂) As template agent, the synthesis process is according to 1.0iPrNH₂:Ga₂O₃:P₂O₅:40H₂The molar ratio of O.

In 2004, the literature (organic Chemistry,2004,43,2703-2707) reported an AFN structure molecular sieve MnAPO-14 consisting of three elements of manganese, phosphorus and aluminum. The molecular sieve is synthesized by crystallization for 6 days at 180 ℃ under hydrothermal condition, phosphoric acid is adopted as a phosphorus source, aluminum isopropoxide is adopted as an aluminum source, manganese chloride tetrahydrate is adopted as a manganese source, and 1, 4-diazabicyclo [2.2.2]Octane (DABCO) is used as a template agent, and the synthesis process is carried out according to (0.5-1.5) MnCl₂·4H₂O:1.0Al(ⁱPrO)₃:4.0H₃PO₄:4.0DABCO:500H₂The molar ratio of O. 2005, literature (microporouus and)Mesoporus Materials,2005, 85, 252-. The synthesis crystallization conditions and raw materials of the molecular sieve are the same as those of the MnAPO-14 molecular sieve, except that the template agent is changed into 1, 3-propane diamine (1,3-PDA) and oxalic acid is added, and the molar ratio in the synthesis process is 1.0MnCl₂·4H₂O:1.4Al(ⁱPrO)₃:5.0H₃PO₄:1.60H₂C₂O₄:(4-6)1,3-PDA:920H₂O。

In 2016, CN108147423A reported a method for synthesizing AFN structure molecular sieve SAPO-14 consisting of silicon, phosphorus and aluminum elements. The molecular sieve is prepared by taking 1-isopropyl-4-piperidone as a template agent and adopting a phase inversion method or a hydrothermal method for a dry colloidal solution of phosphorus and aluminum. In the embodiment 1, aluminum hydroxide dry glue, orthophosphoric acid and solid silica gel are used as raw materials, and the molar ratio in the synthesis process is as follows: 1.0P₂O₅:1.0Al₂O₃:0.15SiO₂:2.0R:20H₂O, crystallizing at 150 ℃ for 36 hours under the hydrothermal condition, then heating to 180 ℃, and carrying out second-stage crystallization: crystallizing at 180 deg.C for 45 hr.

In summary, the AFN molecular sieves synthesized at present include four types: the synthesis of AFN structure molecular sieves consisting of AlPO-14, SAPO-14, GaPO-14, MnAPO-14 and other elements is not reported.

Disclosure of Invention

The invention aims to provide an AFN structure heteroatom molecular sieve with a framework element formed by magnesium, phosphorus and aluminum, and a preparation method and application thereof.

According to the prior art, the AFN structure molecular sieves synthesized at present comprise four kinds of AlPO-14, SAPO-14, GaPO-14 and MnAPO-14, but the AFN structure molecular sieves consisting of magnesium, phosphorus and aluminum are not synthesized yet. Using isopropylamine as template agent, only synthesizing AFN structure AlPO-14 molecular sieve and GaPO-14 molecular sieve by hydrothermal synthesis method, the synthesis of AFN structure molecular sieve composed of other elements has not been reported.

In order to achieve the above object, according to a first aspect of the present invention, the present invention provides an AFN-structured heteroatom molecular sieve composed of magnesium, phosphorus and aluminum, wherein the heteroatom of the AFN-structured heteroatom molecular sieve is Mg.

Preferably, the XRD pattern of the atomic molecular sieve raw powder with the AFN structure consisting of magnesium, phosphorus and aluminum at least contains diffraction peaks shown in the following table 1;

TABLE 1

2θ(deg)	Relative intensity (100 × I/I)0)
		8.974	100.00
9.460	10.56
		11.141	22.10
13.097	22.84
		13.347	11.64
15.842	15.03
		15.933	15.39
17.956	11.85
		21.776	11.75
22.236	12.45
		22.643	21.16

The table above lists essentially XRD diffraction peak data for relative intensities of 100 × I/I0> 10.

According to a second aspect of the present invention, the present invention provides a synthesis method of an AFN structure heteroatom molecular sieve composed of magnesium, phosphorus and aluminum, wherein the synthesis method comprises:

providing an initial gel mixture containing a dry aluminum phosphate gel, a magnesium source, a templating agent, and water;

crystallizing the initial gel mixture;

carrying out solid-liquid separation on the crystallized product, and washing, drying and optionally roasting the obtained solid phase;

wherein the template agent is isopropylamine.

According to a third aspect of the invention, the invention provides an application of the AFN structure heteroatom molecular sieve composed of magnesium, phosphorus and aluminum in gas adsorption separation.

The inventor of the invention synthesizes an AFN structure molecular sieve which is composed of magnesium, phosphorus and aluminum as framework elements for the first time by taking isopropylamine as a template agent. The inventor successfully synthesizes the magnesium-phosphorus-aluminum heteroatom molecular sieve with the AFN structure by adopting a phosphorus-aluminum dry glue solution phase conversion method.

The prepared heteroatom molecular sieve with the AFN structure and the magnesium, phosphorus and aluminum composition can be used for gas separation and adsorption, and is particularly used for C₃H₆/C₃H₈、CO₂/CH₄、CO₂/N₂And the adsorption separation of the mixed gas has good application prospect.

Drawings

FIG. 1 is an XRD spectrum of a sample of the molecular sieve synthesized in example 1;

fig. 2 is an SEM photograph of a sample of the molecular sieve synthesized in example 1.

FIG. 3 is an XRD spectrum of a sample of the molecular sieve synthesized in example 2;

fig. 4 is an SEM photograph of a sample of the molecular sieve synthesized in example 2.

FIG. 5 is an XRD spectrum of a sample of the molecular sieve synthesized in example 3;

fig. 6 is an SEM photograph of a sample of the molecular sieve synthesized in example 3.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

Technical terms in the present invention are defined in the following, and terms not defined are understood in the ordinary sense in the art.

The templating agent in the present invention is also referred to in the art as a structure directing agent or an organic structure directing agent.

According to a first aspect of the invention, the invention provides an AFN structure heteroatom molecular sieve composed of magnesium, phosphorus and aluminum, wherein the heteroatom of the AFN structure heteroatom molecular sieve is Mg.

According to the invention, the XRD (X-ray diffraction) pattern of the atomic molecular sieve raw powder with the AFN structure consisting of magnesium, phosphorus and aluminum at least contains diffraction peaks shown in the following table 1;

TABLE 1

2θ(deg)	Relative intensity (100 × I/I)0)
		8.974	100.00
9.460	10.56
		11.141	22.10
13.097	22.84
		13.347	11.64
15.842	15.03
		15.933	15.39
17.956	11.85
		21.776	11.75
22.236	12.45
		22.643	21.16

The table above lists essentially XRD diffraction peak data for relative intensities of 100 × I/I0> 10.

The AFN magnesium-phosphorus-aluminum molecular sieve can be proved to be obtained through diffraction peak data contained in the XRD spectrum of the AFN structure magnesium-phosphorus-aluminum molecular sieve raw powder and unit cell parameter data of the AFN structure magnesium-phosphorus-aluminum molecular sieve.

The synthesis method of the AFN structure magnesium-phosphorus-aluminum molecular sieve provided by the invention is a phosphorus-aluminum dry glue solution phase inversion method taking isopropylamine as a template agent.

According to the second aspect of the invention, the synthesis method of the magnesium-phosphorus-aluminum containing AFN structure heteroatom molecular sieve comprises the following steps:

providing an initial gel mixture containing a dry aluminum phosphate gel, a magnesium source, a templating agent, and water;

crystallizing the initial gel mixture;

and (3) carrying out solid-liquid separation on the crystallized product, and washing, drying and optionally roasting the obtained solid phase.

According to the invention, the molecular sieve is synthesized by adopting a dry phosphorus-aluminum gel liquid phase inversion method, the dry phosphorus-aluminum gel can be prepared by adopting a conventional method, and the dry phosphorus-aluminum gel, a magnesium source, a template agent and water are mixed, so that the initial gel mixture is obtained. Preferably, the preparation method of the phosphorus-aluminum dry glue comprises the following steps: and (3) aging a mixture containing a phosphorus source, an aluminum source and water, and then drying to obtain the phosphorus-aluminum dry glue.

Specifically, an aluminum source and water are mixed, then the phosphorus source is added with stirring to obtain a mixture containing the phosphorus source, the aluminum source and the water, the mixture is aged with stirring, the aging temperature can be 50-80 ℃, preferably 60-70 ℃, the aging time can be 6-20 hours, preferably 10-18 hours, then the aged mixture is dried, the drying temperature can be 80-110 ℃, preferably 80-100 ℃, and the drying time can be 15-35 hours, preferably 20-30 hours, and the phosphorus aluminum dry glue is prepared.

According to the specific embodiment of the invention, the phase inversion method of the phosphor-aluminum dry glue solution comprises the following steps:

(1) providing a mixture comprising a source of phosphorus, a source of aluminum, and water;

(2) aging the mixture obtained in the step (1), and then drying to obtain a phosphorus-aluminum dry adhesive;

(3) providing an initial gel mixture, wherein the initial gel mixture contains the phosphorus-aluminum dry glue prepared in the step (2), a magnesium source, a template agent and water;

(4) crystallizing the initial gel mixture of step (3);

(5) and (3) carrying out solid-liquid separation on the crystallized product, and washing, drying and optionally roasting the obtained solid phase.

According to the above synthesis method of the present invention, the template agent is isopropylamine.

Herein, "at least one" means one or two or more.

According to the invention, the molecular sieve is synthesized by adopting a phosphorus-aluminum dry glue liquid phase inversion method, and when the mixture is prepared, the mixture contains a phosphorus source, an aluminum source and water, wherein the phosphorus source is P₂O₅The aluminum source is calculated as Al₂O₃The molar ratio of the phosphorus source to the aluminum source to the water is 0.6-1.2:1:30-70, preferably 0.8-1.2:1: 35-65. The water is the total amount of water in preparing the mixture, including, for example, added water, as well as water from sources of phosphorus and aluminum. When preparing the initial gel mixture, the initial gel mixture contains the phosphorus aluminum dry glue prepared in the step (2), a magnesium source, a template agent and water, and the phosphorus aluminum dry glue is prepared from Al₂O₃The magnesium source is calculated by MgO, and the molar ratio of the phosphorus-aluminum dry glue to the magnesium source to the template to the water is 1:0.01-0.6:1-3:10-200, preferably 1:0.1-0.5:1.5-3: 20-120. The water is the total amount of water in preparing the initial gel mixture, including, for example, the added water, as well as the amount of water in the phosphor-aluminum dry gel, magnesium source, and templating agent. According to the present invention, the initial gel mixture may be prepared by a conventional method, and preferably, the aluminum phosphate dry glue, the magnesium source, the water and the template agent are sequentially added and uniformly mixed to obtain the initial gel mixture.

In the present invention, the types of the phosphorus source, the magnesium source, and the aluminum source are not particularly limited and may be selected conventionally.

Generally, the phosphorus source may be selected from at least one of orthophosphoric acid, phosphorous acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate and an organic phosphide.

Preferably, the organophosphate is at least one of trimethylphosphorus and triethylphosphorous.

The aluminum source may be at least one selected from the group consisting of aluminum salt, pseudoboehmite, aluminum isopropoxide, aluminum hydroxide dry gel and activated alumina.

Preferably, the aluminum salt is at least one of aluminum chloride and aluminum sulfate.

The magnesium source may be selected from at least one of magnesium acetate tetrahydrate, magnesium nitrate hexahydrate and magnesium phosphate octahydrate, preferably magnesium acetate tetrahydrate.

According to the invention, the crystallization process can be carried out at a single-stage temperature or can be carried out at a two-stage variable temperature.

When the crystallization process is carried out at a single-stage temperature, the crystallization is generally carried out under the autogenous pressure and at the temperature of 170 ℃ and 210 ℃ for 30-92 hours; preferably, the crystallization is carried out for 40-85 hours under the autogenous pressure and at the temperature of 170-200 ℃; more preferably, the crystallization is carried out under autogenous pressure at 190 ℃ for 50-80 hours.

Preferably, the crystallization process adopts two-stage variable temperature crystallization, that is, the crystallization process includes a first stage crystallization and a second stage crystallization, and generally, the first stage crystallization temperature is lower than the second stage crystallization temperature, and the crystallization conditions of each stage are respectively and independently: the first section of crystallization is carried out for 25 to 45 hours under the autogenous pressure and the temperature of 130-170 ℃, and the second section of crystallization is carried out for 30 to 55 hours under the autogenous pressure and the temperature of 170-200 ℃; preferably, the first-stage crystallization is performed at the autogenous pressure and the temperature of 140-165 ℃ for 25-40 hours, and the second-stage crystallization is performed at the autogenous pressure and the temperature of 170-195 ℃ for 35-50 hours; more preferably, the first-stage crystallization is performed at the autogenous pressure and the temperature of 140 ℃ and 160 ℃ for 30-40 hours, and the second-stage crystallization is performed at the autogenous pressure and the temperature of 175 ℃ and 190 ℃ for 40-50 hours.

According to the invention, the temperature rising mode of any step in the synthesis method of the AFN structure molecular sieve composed of magnesium, phosphorus and aluminum is not particularly limited, and a temperature programming mode can be adopted, for example, 0.5-5 ℃/min.

According to the invention, the pressure of the crystallization process in the synthesis method of the AFN structure molecular sieve composed of magnesium, phosphorus and aluminum is not particularly limited, and can be the autogenous pressure of a crystallization system.

According to the invention, the solid phase obtained by performing solid-liquid separation and water washing on the mixture obtained by crystallization can be dried and optionally calcined under conventional conditions, so as to obtain the molecular sieve. In the present invention, "optional" means unnecessary, and may be understood as either included or excluded. Specifically, the drying may be performed at a temperature of 90 to 120 ℃, and the drying time may be selected according to the drying temperature, and may be generally 6 to 14 hours. The roasting aims to remove the template agent remained in the molecular sieve pore channel in the molecular sieve synthesis process, and whether the roasting is carried out can be determined according to specific use requirements. It is preferable to perform the calcination after the completion of the drying. The calcination may be carried out at a temperature of 400-700 ℃, and the duration of the calcination may be selected according to the calcination temperature, and may be generally 3 to 6 hours. The calcination is generally carried out in an air atmosphere. In addition, the solid phase obtained by solid-liquid separation is washed before being dried, namely, the crystallized product obtained by hydrothermal crystallization is subjected to solid-liquid separation, washing and drying to obtain the molecular sieve raw powder; or, carrying out solid-liquid separation, washing, drying and roasting on a crystallization product obtained by hydrothermal crystallization to obtain the roasted hydrogen type molecular sieve. The washing method can be carried out by a conventional method, and in order to avoid introducing other impurities, deionized water is preferably used for washing until the washing is neutral. The solid-liquid separation method can be carried out by a conventional method such as filtration, centrifugal separation, etc.

According to the third aspect of the invention, the invention also provides the application of the AFN structure heteroatom molecular sieve consisting of magnesium, phosphorus and aluminum in gas adsorption separation, in particular to C₃H₆/C₃H₈、CO₂/CH₄、CO₂/N₂Has good application in the adsorption separation of mixed gasesAnd (4) foreground.

The present invention will be described in detail below by way of examples.

In the following examples, X-ray powder diffraction phase analysis (XRD) was carried out using an Empyrean type diffractometer of the Parnake, the Netherlands, equipped with PIXcel^3DA detector. And (3) testing conditions are as follows: cu target, Ka radiation, Ni filter, tube voltage 40kV, tube current 40mA, and scanning range 5-50 deg.

In the following examples, scanning electron microscopy morphology analysis (SEM) was performed using a scanning electron microscope, type S4800 Hitachi, Japan. And (3) testing conditions are as follows: after the sample was dried and ground, it was stuck on a conductive gel. The accelerating voltage of the analysis electron microscope is 5.0kV, and the magnification is 20-800000 times.

In the following examples, semi-quantitative analysis of chemical elements was performed by X-ray fluorescence spectroscopy (XRF) on a Philips Magi X-ray fluorescence spectrometer. And (3) testing conditions are as follows: a tungsten target is used as a ray source, the excitation voltage is set to be 40kV, and the excitation current is set to be 50 mA.

In the following examples, R represents a template, and the template is isopropylamine.

Examples 1-6 are presented to illustrate the synthesis of the AFN-structured heteroatomic molecular sieve composed of magnesium, phosphorus and aluminum according to the present invention using a dry colloidal solution phase inversion method of phosphorus and aluminum.

Example 1

16.67 g of aluminum isopropoxide (C)₉H₂₁AlO₃98 percent of mass fraction) and 28.40 g of deionized water are stirred and mixed until uniform, and 9.30 g of ammonium dihydrogen phosphate (NH) is slowly added under stirring₄H₂PO₄99% by mass), stirring thoroughly at 50 ℃ and aging for 20 hours to give a mixture A. And pouring the mixture A into a tray, and drying at 90 ℃ for 24 hours to obtain the phosphorus-aluminum dry glue.

5.85 g of the prepared dry aluminophospho-gel (83.36% solids) were added to a polytetrafluoroethylene liner, followed by 0.65 g of magnesium acetate tetrahydrate (Mg (OAc)₂·4H₂99% by mass of O), 9.60 g of deionized water, 1.79 g of isopropylamine (C)₃H₉99 percent of N by mass) and uniformly stirring, wherein the adding molar ratio of each component is as follows: p₂O₅/Al₂O₃＝1.0、Mg(OAc)₂·4H₂O/Al₂O₃＝0.15、R/Al₂O₃＝1.5、H₂O/Al₂O₃＝30。

Covering the polytetrafluoroethylene lining filled with the reaction mixture, placing the polytetrafluoroethylene lining into a stainless steel autoclave for sealing, placing the autoclave into a rotary convection oven, setting the rotating speed at 20r/min, and performing first-stage crystallization under the autogenous pressure: crystallizing at 155 ℃ for 38 hours, heating to 185 ℃, and performing second-stage crystallization: crystallizing at 185 deg.C for 45 hr, cooling to room temperature, filtering or centrifuging, washing the obtained solid phase with deionized water to neutrality, and drying at 110 deg.C for 12 hr to obtain molecular sieve powder.

The obtained molecular sieve is subjected to X-ray diffraction analysis, and an XRD spectrogram is shown in figure 1, so that the molecular sieve is proved to be a pure-phase AFN structure magnesium-phosphorus-aluminum molecular sieve. The morphology of the molecular sieve was observed by SEM, and the SEM photograph is shown in fig. 2, showing a sheet-like morphology.

Example 2

4.16 g of activated alumina (Al)₂O₃98 percent by mass) and 33.97 g of deionized water are stirred and mixed until uniform, and 11.15 g of phosphorous acid (H) is slowly added in a trickle manner under the stirring state₃PO₃50% by mass), stirring thoroughly at 80 ℃ and aging for 8 hours to obtain a mixture A. And pouring the mixture A into a tray, and drying at 105 ℃ for 20 hours to obtain the aluminum phosphate dry glue.

5.47 g of the prepared dry aluminophospho-gel (81.37% solids) were added to a polytetrafluoroethylene liner, followed by 0.87 g of magnesium acetate tetrahydrate (Mg (OAc)₂·4H₂99% by mass of O), 13.08 g of deionized water, 2.39 g of isopropylamine (C)₃H₉99 percent of N by mass) and uniformly stirring, wherein the adding molar ratio of each component is as follows: p₂O₅/Al₂O₃＝0.85、Mg(OAc)₂·4H₂O/Al₂O₃＝0.20、R/Al₂O₃＝2.0、H₂O/Al₂O₃＝40。

Covering the polytetrafluoroethylene lining filled with the reaction mixture, placing the polytetrafluoroethylene lining into a stainless steel autoclave for sealing, placing the autoclave into a rotary convection oven, setting the rotating speed at 20r/min, and performing first-stage crystallization under the autogenous pressure: crystallizing at 165 ℃ for 28 hours, heating to 190 ℃, and performing second-stage crystallization: crystallizing at 190 deg.C for 40 hr, cooling the autoclave to room temperature, taking out crystallized product, filtering or centrifuging, washing the obtained solid phase with deionized water to neutrality, and drying at 110 deg.C for 12 hr to obtain molecular sieve powder.

The obtained molecular sieve is subjected to X-ray diffraction analysis, and an XRD spectrogram is shown in figure 3, so that the molecular sieve is proved to be a pure-phase AFN structure magnesium-phosphorus-aluminum molecular sieve. The morphology of the molecular sieve was observed by SEM, and the SEM photograph is shown in fig. 4, showing a sheet-like morphology. XRF is adopted to analyze the obtained molecular sieve, and the actual element composition of the obtained sample is Mg_0.052Al_0.489P_0.459。

Example 3

10.78 g of aluminum chloride (AlCl)₃99 percent of mass fraction) and 31.00 g of deionized water are stirred and mixed until uniform, and 8.76 g of orthophosphoric acid (H) is slowly added in a trickle manner under the stirring state₃PO₄85% by mass), stirring thoroughly at 70 ℃ and aging for 14 hours to obtain a mixture A. And pouring the mixture A into a tray, and drying at 80 ℃ for 30 hours to obtain the aluminum phosphate dry glue.

5.51 g of the prepared dry aluminum phosphate gel (85.88% solids) were added to a polytetrafluoroethylene liner, followed by 0.84 g of magnesium phosphate octahydrate (Mg)₃(PO₄)₂·8H₂97% by mass of O), 24.12 g of deionized water, 2.99 g of isopropylamine (C)₃H₉99 percent of N by mass) and uniformly stirring, wherein the adding molar ratio of each component is as follows: p₂O₅/Al₂O₃＝0.95、Mg₃(PO₄)₂·8H₂O/Al₂O₃＝0.10、R/Al₂O₃＝2.5、H₂O/Al₂O₃＝70。

Covering the polytetrafluoroethylene lining filled with the reaction mixture, placing the polytetrafluoroethylene lining into a stainless steel autoclave for sealing, placing the autoclave into a rotary convection oven, setting the rotating speed at 20r/min, and performing single-stage crystallization under the autogenous pressure: crystallizing at 190 deg.C for 55 hr, cooling the autoclave to room temperature, taking out crystallized product, filtering or centrifuging, washing the obtained solid phase with deionized water to neutrality, and drying at 110 deg.C for 12 hr to obtain molecular sieve powder.

The obtained molecular sieve is subjected to X-ray diffraction analysis, and an XRD spectrogram is shown in figure 5, so that the molecular sieve is proved to be a pure-phase AFN structure magnesium-phosphorus-aluminum molecular sieve. The morphology of the molecular sieve was observed by SEM, and the SEM photograph is shown in fig. 6, showing a sheet-like morphology. XRF is adopted to analyze the obtained molecular sieve, and the actual element composition of the obtained sample is Mg_0.030Al_0.504P_0.466。

Example 4

4.91 g of pseudo-boehmite (Al)₂O₃83 percent of mass fraction) and 24.16 g of deionized water are stirred and mixed until uniform, and 11.32 g of ammonium hydrogen phosphate ((NH) is slowly added in a trickle manner under the stirring state₄)₂HPO₄98% by mass), and aging at 70 ℃ for 12 hours to obtain a mixture A. And pouring the mixture A into a tray, and drying at 80 ℃ for 24 hours to obtain the phosphorus-aluminum dry glue.

5.99 g of the prepared dry aluminum phosphate gel (83.96% solids) were added to a polytetrafluoroethylene liner, followed by 1.30 g of magnesium acetate tetrahydrate (Mg (OAc)₂·4H₂99% by mass of O), 16.60 g of deionized water, 1.79 g of isopropylamine (C)₃H₉99 percent of N by mass) and uniformly stirring, wherein the adding molar ratio of each component is as follows: p₂O₅/Al₂O₃＝1.05、Mg(OAc)₂·4H₂O/Al₂O₃＝0.30、R/Al₂O₃＝1.5、H₂O/Al₂O₃＝50。

Covering the polytetrafluoroethylene lining filled with the reaction mixture, placing the polytetrafluoroethylene lining into a stainless steel autoclave for sealing, placing the autoclave into a rotary convection oven, setting the rotating speed at 20r/min, and performing first-stage crystallization under the autogenous pressure: crystallizing at 150 ℃ for 36 hours, heating to 180 ℃ again, and carrying out second-stage crystallization: crystallizing at 180 deg.C for 45 hr, cooling the autoclave to room temperature, taking out crystallized product, filtering or centrifuging, washing the obtained solid phase with deionized water to neutrality, and drying at 110 deg.C for 12 hr to obtain molecular sieve powder.

And (3) carrying out X-ray diffraction analysis on the obtained molecular sieve and observing the morphology of the molecular sieve by adopting SEM (scanning Electron microscope), wherein the characterization result shows that the sample is a pure-phase AFN structure magnesium-phosphorus-aluminum molecular sieve and the morphology of the sample is a flaky morphology. XRF is adopted to analyze the obtained molecular sieve, and the actual element composition of the obtained sample is Mg_0.064Al_0.492P_0.444。

Example 5

4.16 g of activated alumina (Al)₂O₃98 percent of mass fraction) and 41.63 g of deionized water are stirred and mixed until uniform, and 10.15 g of phosphorous acid (H) is slowly added in a trickle manner under the stirring state₃PO₃50% by mass), stirring thoroughly at 60 ℃ and aging for 18 hours to obtain a mixture A. And pouring the mixture A into a tray, and drying at 100 ℃ for 21 hours to obtain the phosphorus-aluminum dry glue.

5.88 g of the prepared dry aluminum phosphate gel (87.77% solids) were added to a polytetrafluoroethylene liner, followed by 2.17 g of magnesium acetate tetrahydrate (Mg (OAc)₂·4H₂99% by mass of O), 34.57 g of deionized water, 2.39 g of isopropylamine (C)₃H₉99 percent of N by mass) and uniformly stirring, wherein the adding molar ratio of each component is as follows: p₂O₅/Al₂O₃＝1.10、Mg(OAc)₂·4H₂O/Al₂O₃＝0.50、R/Al₂O₃＝2.0、H₂O/Al₂O₃＝100。

Covering the polytetrafluoroethylene lining filled with the reaction mixture, placing the polytetrafluoroethylene lining into a stainless steel autoclave for sealing, placing the autoclave into a rotary convection oven, setting the rotating speed at 20r/min, and performing single-stage crystallization under the autogenous pressure: crystallizing at 170 deg.C for 72 hr, cooling to room temperature, filtering or centrifuging, washing the obtained solid phase with deionized water to neutrality, and drying at 110 deg.C for 12 hr to obtain molecular sieve powder.

And (3) carrying out X-ray diffraction analysis on the obtained molecular sieve and observing the morphology of the molecular sieve by adopting SEM (scanning Electron microscope), wherein the characterization result shows that the sample is a pure-phase AFN structure magnesium-phosphorus-aluminum molecular sieve and the morphology of the sample is a flaky morphology.

Example 6

4.91 g of pseudo-boehmite (Al)₂O₃83 percent of mass fraction) and 48.36 g of deionized water are stirred and mixed until uniform, and 8.30 g of orthophosphoric acid (H) is slowly added in a trickle manner under the stirring state₃PO₄85% by mass) was thoroughly stirred at 65 ℃ and aged for 18 hours to obtain a mixture A. And pouring the mixture A into a tray, and drying at 90 ℃ for 22 hours to obtain the phosphorus-aluminum dry glue.

5.13 g of the prepared dry aluminum phosphate gel (89.56% solids) were added to a polytetrafluoroethylene liner, followed by 0.84 g of magnesium phosphate octahydrate (Mg)₃(PO₄)₂·8H₂97% by mass of O), 6.35 g of deionized water, 3.58 g of isopropylamine (C)₃H₉99 percent of N by mass) and uniformly stirring, wherein the adding molar ratio of each component is as follows: p₂O₅/Al₂O₃＝0.90、Mg₃(PO₄)₂·8H₂O/Al₂O₃＝0.10、R/Al₂O₃＝3.0、H₂O/Al₂O₃＝20。

Covering the polytetrafluoroethylene lining filled with the reaction mixture, placing the polytetrafluoroethylene lining into a stainless steel autoclave for sealing, placing the autoclave into a rotary convection oven, setting the rotating speed at 20r/min, and performing first-stage crystallization under the autogenous pressure: crystallizing at 140 ℃ for 40 hours, then heating to 180 ℃ to carry out second-stage crystallization: crystallizing at 180 deg.C for 48 hr, cooling the autoclave to room temperature, taking out crystallized product, filtering or centrifuging, washing the obtained solid phase with deionized water to neutrality, and drying at 110 deg.C for 12 hr to obtain molecular sieve powder.

And (3) carrying out X-ray diffraction analysis on the obtained molecular sieve and observing the morphology of the molecular sieve by adopting SEM (scanning Electron microscope), wherein the characterization result shows that the sample is a pure-phase AFN structure magnesium-phosphorus-aluminum molecular sieve and the morphology of the sample is a flaky morphology.

Comparative example 1

A molecular sieve was synthesized according to the procedure of example 1, except that the comparative example employed a hydrothermal synthesis.

8.34 g of aluminum isopropoxide (C)₉H₂₁AlO₃98% by mass), 10.36 g of deionized water, 4.65 g of ammonium dihydrogen phosphate (NH)₄H₂PO₄99% by mass), 0.65 g of magnesium acetate tetrahydrate (Mg (OAc)₂·4H₂99% by mass of O), 1.79 g of isopropylamine (C)₃H₉99 percent of N by mass) are sequentially added into the polytetrafluoroethylene lining and stirred uniformly, wherein the adding molar ratio of each component is as follows: p₂O₅/Al₂O₃＝1.0、Mg(OAc)₂·4H₂O/Al₂O₃＝0.15、R/Al₂O₃＝1.5、H₂O/Al₂O₃＝30。

Covering the polytetrafluoroethylene lining filled with the reaction mixture, placing the polytetrafluoroethylene lining into a stainless steel autoclave for sealing, placing the autoclave into a rotary convection oven, setting the rotating speed at 20r/min, and performing first-stage crystallization under the autogenous pressure: crystallizing at 155 ℃ for 38 hours, heating to 185 ℃, and performing second-stage crystallization: crystallizing at 185 deg.C for 45 hr, cooling to room temperature, filtering or centrifuging, washing the obtained solid phase with deionized water to neutrality, and drying at 110 deg.C for 12 hr to obtain molecular sieve powder.

The obtained solid was analyzed by X-ray diffraction and confirmed to be an amorphous phase, and it was found that a magnesium-phosphorus-aluminum molecular sieve having an AFN structure could not be synthesized by the hydrothermal synthesis method.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.