阅读说明：本技术 一种选择性加氢分子筛材料及其制备方法 (Selective hydrogenation molecular sieve material and preparation method thereof ) 是由 王振宇 郑步梅 王丽博 艾抚宾 于 2019-10-30 设计创作，主要内容包括：本发明公开了一种惰性分子筛材料及其制备方法。所述分子筛材料为骨架含Pd和Ni的全硅β分子筛；以全硅β分子筛的重量为基准,Pd以元素计的含量为0.05%～1.5%,Ni以元素计的含量为0.05%～8%。本发明方法中,金属Pd和Ni在全硅型β分子筛合成过程中加入,Pd离子和Ni离子分别与乙二胺形成络合离子,在晶化时呈均匀的高分散相；在使模板剂分解的过程中,Ni～(2+)和Pd～(2+)进入分子筛骨架。所制备的分子筛中,Ni与Pd产生协同催化作用,抑制了1-丁烯加氢活性,提高了二烯烃加氢选择性。(The invention discloses an inert molecular sieve material and a preparation method thereof. The molecular sieve material is an all-silicon beta molecular sieve with a framework containing Pd and Ni; based on the weight of the all-silicon beta molecular sieve, the content of Pd is 0.05-1.5% by element, and the content of Ni is 0.05-8% by element. In the method, metal Pd and Ni are added in the synthesis process of the all-silicon beta molecular sieve, and Pd ions and Ni ions respectively form complex ions with ethylenediamine, so that the Pd ions and the Ni ions are in a uniform high-dispersion phase during crystallization; in the process of decomposing the template, Ni 2+ And Pd 2+ Entering the framework of the molecular sieve. In the prepared molecular sieve, Ni and Pd generate a synergistic catalytic action, so that the hydrogenation activity of 1-butene is inhibited, and the hydrogenation selectivity of diolefin is improved.)

1. An inert molecular sieve material containing Pd and Ni, wherein the molecular sieve material is an all-silicon beta molecular sieve of which the framework contains Pd and Ni; based on the weight of the all-silicon beta molecular sieve, the content of Pd is 0.05-1.5% by element, and the content of Ni is 0.5-8% by element.

2. The molecular sieve material of claim 1, wherein Pd is present in an amount of 0.3% to 1.0% elemental basis; the content of Ni in terms of elements is 1.0% -5.5%.

3. A process for preparing the molecular sieve material of claim 1 or 2, comprising:

(1) adding a proper amount of white carbon black into the aqueous solution of TEAOH, and fully and uniformly stirring;

(2) adding a Pd precursor and a Ni precursor into the mixture obtained in the step (1), adding a proper amount of ethylenediamine, and fully and uniformly mixing;

(3) adding ammonium fluoride into the mixture obtained in the step (2), and fully stirring until a solid viscous colloid is formed;

(4) performing crystallization reaction on the colloid obtained in the step (3) at a certain temperature;

(5) and (4) filtering and washing the crystallized product obtained in the step (4), drying in a non-oxidizing atmosphere, and roasting to obtain the all-silicon beta molecular sieve material with the framework containing Pd and Ni.

4. The method according to claim 3, wherein the mixture of the white carbon black and the aqueous solution of TEAOH in the step (1) has a molar ratio of SiO to TEAOH₂:TEAOH:H₂O= 1:(0.1~1):(3~10)，SiO₂:TEAOH:H₂O=1:(0.25~0.8):(3.5~7.5)。

5. A production method according to claim 3, wherein the Pd precursor is at least one selected from the group consisting of palladium nitrate, palladium chloride, palladium acetate, palladium oxalate, palladium tetraammine dihydroxide, palladium tetraammine chloride, palladium acetylacetonate, palladium tetraammine acetate, and palladium tetraammine hydrogencarbonate; the precursor of Ni is at least one selected from nickel nitrate, nickel acetate, nickel chloride, nickel sulfate and nickel hexamine chloride.

6. The preparation method according to claim 3, wherein the molar ratio of the addition amount of the Pd precursor and the Ni precursor in the step (2) to the addition amount of the white carbon black in the step (1) based on Pd, Ni and Si atoms is as follows: 100 (0.12-3.45) (0.35-16.88), preferably Si Pd Ni =100 (0.68-2.45) (3.5-12.5).

7. The method according to claim 3, wherein the molar ratio of ethylenediamine to white carbon black is ethylenediamine SiO₂And (b) =1: 30-1: 5, preferably 1: 20-1: 10.

8. The method according to claim 3, wherein the molar ratio of ammonium fluoride to silica in step (3) is SiO₂: NH₄F =1:3 to 1:10, preferably 1:4 to 1: 8.

9. The method according to claim 3, wherein the crystallization conditions in the step (4) are: the crystallization temperature is 100-200 ℃, preferably 135-165 ℃; the crystallization time is 22 to 180 hours, preferably 72 to 144 hours.

10. The method according to claim 3, wherein the drying conditions in the step (5) are: 80-200 ℃, preferably 110-130 ℃; the drying time is 5-48 hours, preferably 10-30 hours; the roasting conditions are as follows: raising the temperature to 250 ℃ for 1 hour at room temperature, keeping the temperature for 2-6 hours, raising the temperature to 400 ℃ for 1 hour, keeping the temperature for 2-6 hours, raising the temperature to 550 ℃ for 1 hour, and keeping the temperature for 2-6 hours.

11. The method according to claim 3, wherein the atmosphere for drying and baking is a nitrogen, hydrogen, helium, carbon monoxide or methane atmosphere.

Technical Field

The invention relates to a selective hydrogenation catalyst and a preparation method thereof, in particular to a supported catalyst for selective hydrogenation of dialkene and alkyne and a preparation method thereof.

Background

In the existing oil refining process, trace alkyne and dialkene contained in light hydrocarbon fractions produced in the processes of steam cracking, catalytic cracking, thermal cracking and the like often bring troubles to the downstream process. Such as when a small amount of butadiene is present in the butene rich fraction, the presence of a trace amount of butadiene makes 1-butene, one of the comonomers, not to meet quality requirements in the copolymerization reaction for producing Linear Low Density Polyethylene (LLDPE); in the alkylation reaction for producing gasoline, butadiene can generate heavy compounds, so that the dry point of alkylate oil is increased, the octane number is reduced, and the acid consumption is increased; in the etherification reaction for producing methyl tert-butyl ether (MTBE), butadiene is easy to polymerize on etherified resin to form colloid, so that the catalyst pore channels are blocked, and the service life of the catalyst is shortened. Such processes often require a diene mass fraction in the feed of less than 1X 10^-5Some polymerization reactions even require diene mass fractions of less than 1X 10^-6. But actually C₄The mass fraction of butadiene in the fraction is 0.2-2.0%.

In order to solve such problems, the raw materials must be pretreated and optimized before entering the reaction unit, so that useful components are appropriately concentrated and alkynes and diolefins are removed, and the adoption of a selective hydrogenation process is an economical and convenient method.

The first generation of selective hydrogenation catalysts, produced in the end of the 40's of the 20 th century, were used in the purification of alkylated feedstocks of olefins, the active component being nickel or copper sulfide, which has a low hydrogenation activity and a high reaction temperature, liable to cause side reactions of the polymerization of the olefinic bonds. The second generation selective hydrogenation catalyst was developed in the early 60's of the 20 th century, and people were looking at group VIII noble metals. The research shows that the palladium not only has good hydrogenation activity on acetylene bonds and diene bonds, but also has good hydrogenation selectivity, and is known as the most excellent active component of the selective hydrogenation catalyst for the acetylene bonds and the diene. Therefore, the catalyst using palladium as an active component is rapidly in C₂～C₄The industrial unit for selective hydrogenation refining of olefin occupies a main position.

However, at the same time, palladium metal as an active component also has certain disadvantages: (1) with the selective hydrogenation of unsaturated bonds on palladium, oligomerization side reactions can be generated in parallel, which not only causes the reduction of selectivity, but also causes the pollution of oligomers on the surface of the catalyst to inhibit the activity and reduce the stability; (2) the strong coordination of acetylene bonds and palladium atoms enables the palladium component to be gradually dissolved into a reaction hydrocarbon medium along with the adsorption hydrocarbon, so that the catalyst is permanently inactivated; (3) the activity of palladium for transposition of double bonds of 1-butene into 2-butene is in direct proportion to the activity of butadiene for selective hydrogenation to 1-butene, so that the selectivity of the target product 1-butene is reduced; (4) palladium can be poisoned by the action of mercaptan, carbonyl sulfide and arsenic impurities in the reactants, the activity gradually decreases, etc.

To solve the problem (1), an inert carrier such as α/δ/θ -Al is usually selected₂O₃Carbon materials, spinels, and the like. Such as Chinese patents CN1071443A, CN1181283A, CN1266085A, CN1485411A, CN1565725A, CN1565726A, CN1966480A, CN101429453A, CN101433845A, CN103406121A and the like.

To solve the problem (3), another metal promoter, such as Ag, Zn, alkali metal or alkaline earth metal, is usually introduced into the catalyst by impregnation loading. Such as Chinese patents CN106345508A, CN1317367A, CN1429889A, CN1466486A, CN101146614A and the like.

However, the solutions to the problems (2) and (4) are still insufficient.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides an inert molecular sieve material containing Pd and Ni and a preparation method thereof.

The invention provides an inert molecular sieve material containing Pd and Ni, wherein the molecular sieve material is an all-silicon beta molecular sieve of which the framework contains Pd and Ni; based on the weight of the all-silicon beta molecular sieve, the content of Pd calculated by elements is 0.05-1.5%, preferably 0.3-1.0%; the content of Ni in terms of elements is 0.5-8%, preferably 1.0-5.5%.

The second aspect of the present invention also provides a preparation method of the above molecular sieve material, comprising the following steps:

(1) adding a proper amount of white carbon black into the aqueous solution of TEAOH, and fully and uniformly stirring;

(2) adding a Pd precursor and a Ni precursor into the mixture obtained in the step (1), adding a proper amount of ethylenediamine, and fully and uniformly mixing;

(3) adding ammonium fluoride into the mixture obtained in the step (2), and fully stirring until a solid viscous colloid is formed;

(4) performing crystallization reaction on the colloid obtained in the step (3) at a certain temperature;

(5) and (4) filtering and washing the crystallized product obtained in the step (4), drying in a non-oxidizing atmosphere, and roasting to obtain the all-silicon beta molecular sieve material with the framework containing Pd and Ni.

In the method, the molar ratio of each component in the mixture formed by the white carbon black and the TEAOH aqueous solution in the step (1) is SiO₂:TEAOH:H₂O =1 (0.1-1) and (3-10), preferably SiO₂:TEAOH:H₂O=1:(0.25~0.8):(3.5~7.5)。

In the method of the present invention, the precursor of the active component Pd in step (2) may be palladium nitrate, palladium chloride, palladium acetate, palladium oxalate, palladium tetraammine dihydroxide, palladium tetraammine chloride, palladium acetylacetonate, palladium tetraammine acetate, palladium tetraammine bicarbonate, preferably palladium tetraammine chloride. The precursor of Ni may be nickel nitrate, nickel acetate, nickel chloride, nickel sulfate, nickel hexammine chloride, etc., and nickel hexammine chloride is preferred.

In the method of the present invention, the addition amount of the Pd and Ni precursor in step (2) and the addition amount of the white carbon black in step (1) are, in terms of the mole ratio of Pd, Ni and Si atoms: the Si is Pd: Ni =100 (0.028-0.85) and (0.51-8.14), and the Si is preferably Pd: Ni =100 (0.17-0.58) and (1.0-5.60). The molar ratio of the added ethylenediamine to the white carbon black is ethylenediamine SiO₂And (b) =1: 30-1: 5, preferably 1: 20-1: 10.

In the method of the invention, the molar ratio of the ammonium fluoride added in the step (3) to the white carbon black is SiO₂: NH₄F =1:3 to 1:10, preferably 1:4 to 1: 8.

In the method of the present invention, the crystallization conditions in step (4) are: the crystallization temperature is 100-200 ℃, preferably 135-165 ℃; the crystallization time is 22 to 180 hours, preferably 72 to 144 hours.

In the method of the present invention, the filtration and washing in step (5) are vacuum filtration and deionized water washing well known to those skilled in the art. The drying conditions are as follows: 80-200 ℃, preferably 110-130 ℃; the drying time is 5 to 48 hours, preferably 10 to 30 hours. The roasting conditions are as follows: raising the temperature to 250 ℃ for 1 hour at room temperature, keeping the temperature for 2-6 hours, raising the temperature to 400 ℃ for 1 hour, keeping the temperature for 2-6 hours, raising the temperature to 550 ℃ for 1 hour, and keeping the temperature for 2-6 hours. The drying and roasting atmosphere is non-oxidizing atmosphere, nitrogen, hydrogen, helium, carbon monoxide, methane atmosphere and the like, and preferably hydrogen or carbon monoxide atmosphere.

Pd as an excellent active component of the selective hydrogenation catalyst can show an acidic function under the condition of hydrogenation reaction, the acidity is more strongly shown under the promotion of a certain solid acid catalyst (such as a Si/AI carrier), and the acidic function is used for promoting oligomerization reaction and double bond transfer reaction, so that alkyne and alkene can be oligomerized under the action of palladium to generate oligomer which is called as green oil in industry. The low molecular polymer chain will gradually wind around the surface of the catalyst to isolate active points from reactant molecules and deactivate the active points, which is manifested by reduced time stability and shortened service cycle. In addition, the strong coordination of the acetylenic bond with the palladium atom gradually dissolves the palladium component with the adsorbed hydrocarbon into the reacting hydrocarbon medium, causing permanent deactivation of the catalyst. The activity of palladium on double bond transposition of 1-butene into 2-butene is directly proportional to the activity of selective hydrogenation of butadiene to 1-butene, resulting in a decrease in selectivity of the desired product 1-butene.

The Pd and Ni-containing all-silicon beta molecular sieve is an inert material, has no acid center, and can avoid the oligomerization of alkyne and alkene to generate green oil. The metal Pd and Ni are added in the synthesis process of the all-silicon beta molecular sieve, and Pd ions and Ni ions can respectively form complex ions with ethylenediamine, so that the gel is in a uniform high dispersion phase during crystallization. And in the process of drying and roasting in non-oxidizing atmosphere to decompose the template agent, Ni²⁺And Pd²⁺Entering a molecular sieve framework to form monodisperse Ni atomic sites and sub-nanometer Pd atomic clusters. Each Pd atom being substituted by n atoms of NiAnd (3) sub-coating, wherein n = 3-6, the sub-coating is firmly anchored in a molecular sieve framework, and the Pd component is not dissolved in a reaction hydrocarbon medium in the selective hydrogenation reaction process. Meanwhile, the existence of Ni and Pd generate a synergistic catalytic action, so that the hydrogenation activity of 1-butene is inhibited, and the hydrogenation selectivity of diolefin is improved.

Drawings

FIG. 1 is an XRD spectrum of the catalytic material in example 1 of the present invention.

FIG. 2 is a scanning electron micrograph of the catalytic material of example 1 of the present invention.

Detailed Description

The following examples are given to illustrate the technical aspects of the present invention in detail, but the present invention is not limited to the following examples.

Example 1

60g of white carbon black and 174g of 38 percent TEAOH aqueous solution are mixed and stirred uniformly under the stirring condition, then a proper amount of palladium tetraammine chloride and nickel hexammine chloride are added into the mixture, 6g of ethylenediamine is added after stirring for 0.5 hour, and stirring is continued for 3 hours to prepare uniform gel. Then, 10g of ammonium fluoride was slowly added to the gel under rapid stirring, and stirring was continued for 1 hour to obtain a uniform gel. And (3) transferring the gel into a high-pressure reaction kettle, and crystallizing for 120 hours at 160 ℃. And carrying out suction filtration and washing on the obtained crystallized product to be neutral, then drying at 110 ℃ in a hydrogen atmosphere, and carrying out temperature programming roasting in the hydrogen atmosphere to obtain the Pd and Ni-containing all-silicon beta molecular sieve material. The material is tabletted and crushed to 10-20 meshes, and is marked as A, wherein the content of metal Pd is 0.5%, and the content of Ni is 1.1%.

Comparative example 1

Using alpha-Al₂O₃As a carrier, Pd and Ni components are loaded by a conventional impregnation method to prepare the catalytic material, wherein the material comprises the following metal simple substances in percentage by weight: pd 0.5wt%, Ni 1.1 wt%. This catalyst is designated A1.

Comparative example 2

Referring to Chinese patent CN1181283A, zinc aluminate spinel is used as a carrier, Pd and Ni components are loaded by a conventional impregnation method to prepare the catalytic material, and the weight percentage of each metal simple substance in the material is as follows: pd 0.5wt%, Ni 1.1 wt%. This catalyst is designated A2.

Comparative example 3

60g of white carbon black and 174g of TEAOH aqueous solution with the mass fraction of 38% are mixed under the stirring condition and stirred for 3 hours to prepare uniform gel. Then, 10g of ammonium fluoride was slowly added to the gel under rapid stirring, and stirring was continued for 1 hour to obtain a uniform gel. And (3) transferring the gel into a high-pressure reaction kettle, and crystallizing for 120 hours at 160 ℃. And carrying out suction filtration and washing on the obtained crystallized product to be neutral, then drying at 110 ℃ in an air atmosphere, and then carrying out temperature programming roasting in the air atmosphere. The material is crushed to 10-20 meshes after being pressed into sheets, and Pd and Ni components are loaded by a conventional impregnation method to prepare the catalytic material, wherein the material comprises the following metal simple substances in percentage by weight: pd 0.5wt%, Ni 1.1 wt%. This catalyst is designated A3.

Comparative example 4

Mixing 60g of white carbon black and 174g of TEAOH aqueous solution with the mass fraction of 38% under the stirring condition, uniformly stirring, adding a proper amount of palladium tetraammine chloride into the mixture, stirring for 0.5 hour, adding 6g of ethylenediamine, and continuously stirring for 3 hours to prepare uniform gel. Then, 10g of ammonium fluoride was slowly added to the gel under rapid stirring, and stirring was continued for 1 hour to obtain a uniform gel. And (3) transferring the gel into a high-pressure reaction kettle, and crystallizing for 120 hours at 160 ℃. And carrying out suction filtration and washing on the obtained crystallized product to be neutral, then drying at 110 ℃ in a hydrogen atmosphere, and carrying out temperature programming roasting in the hydrogen atmosphere to obtain the Pd and Ni-containing all-silicon beta molecular sieve material. The material is tabletted and crushed to 10-20 mesh, denoted as A4, wherein the content of metal Pd is 0.5%.

Example 2

Under the condition of stirring, 48g of white carbon black and 170g of TEAOH aqueous solution with the mass fraction of 35% are mixed and stirred uniformly, then a proper amount of palladium tetraammine chloride and nickel hexammine chloride are added into the mixture, after stirring for 0.5 hour, 6.8g of ethylenediamine is added, and stirring is continued for 3 hours to prepare uniform gel. Then, 8g of ammonium fluoride was slowly added to the gel under rapid stirring, and stirring was continued for 1 hour to obtain a uniform gel. And (3) transferring the gel into a high-pressure reaction kettle, and crystallizing for 100 hours at 155 ℃. And carrying out suction filtration and washing on the obtained crystallized product to be neutral, then drying at 120 ℃ in the atmosphere of carbon monoxide, and then carrying out temperature programming roasting in the atmosphere of hydrogen to obtain the Pd and Ni-containing all-silicon beta molecular sieve material. The material is tabletted and crushed to 10-20 meshes, and is marked as B, wherein the content of metal Pd is 0.38%, and the content of Ni is 0.65%.

Example 3

75g of white carbon black and 190g of TEAOH aqueous solution with the mass fraction of 42% are mixed and stirred uniformly under the stirring condition, then a proper amount of palladium tetraammine chloride and nickel hexammine chloride are added into the mixture, 12g of ethylenediamine is added after stirring for 0.5 hour, and stirring is continued for 3 hours to prepare uniform gel. 13g of ammonium fluoride was slowly added to the gel under rapid stirring, and stirring was continued for 1 hour to obtain a uniform gel. And (3) transferring the gel into a high-pressure reaction kettle, and crystallizing at 150 ℃ for 135 hours. And carrying out suction filtration and washing on the obtained crystallized product to be neutral, then drying at 130 ℃ in a hydrogen atmosphere, and carrying out temperature programming roasting in the hydrogen atmosphere to obtain the Pd and Ni-containing all-silicon beta molecular sieve material. The material is tabletted and crushed to 10-20 mesh, denoted as C, with a metal Pd content of 0.65% and a Ni content of 1.82%.

Example 4

N₂The pore properties of the carriers in each of the examples and comparative examples of the physical adsorption measurement are shown in table 1. The contents of Pd and Ni elements determined by ICP elemental analysis are shown in Table 2.

TABLE 1

TABLE 2

The catalytic materials prepared in the above examples and comparative examples were taken to be subjected to C in a micro-reactor₄Evaluation of Selective hydrogenation experiment, C₄The composition of the selected materials is shown in Table 3.

TABLE 3

The catalytic material is reduced by hydrogen, the temperature is raised to 60 ℃, the reaction pressure is 1.2MPa, and the hourly space velocity of the raw material liquid is 17h^-1The hydrogen to hydrocarbon ratio was 1.5. The reaction form was a trickle bed, and the reaction results are shown in Table 4.

TABLE 4