CN113019357A

CN113019357A - Catalyst for preparing propylene by direct dehydrogenation of propane, preparation method and application thereof

Info

Publication number: CN113019357A
Application number: CN201911251582.XA
Authority: CN
Inventors: 刘洁; 刘勇; 刘中民; 朱文良; 倪友明; 刘红超
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2019-12-09
Filing date: 2019-12-09
Publication date: 2021-06-25

Abstract

本发明涉及一种丙烷直接脱氢制丙烯催化剂、其制备方法及应用，包含下式所示组分：A_aCr_bM_cD_dO_x；其中：A为Zn、Mn、Mg、Ni、Co中的至少一种；M为碱金属中的至少一种；D由Cu和Ce组成；a取值为0.01～0.5，b取值为1～10，c取值为0.002～0.1，d取值为0～0.5，x根据除O外的其他各元素的化合价及原子数确定。该催化剂比表面积大，活性高，可以较好地解决现有技术制备的催化剂活性较低的问题。The invention relates to a catalyst for producing propylene by direct dehydrogenation of propane, a preparation method and application thereof, and comprises components represented by the following formula: A _a Cr _b M _c D _d O _x ; wherein: A is Zn, Mn, Mg, Ni, At least one of Co; M is at least one of alkali metals; D is composed of Cu and Ce; a is 0.01 to 0.5, b is 1 to 10, c is 0.002 to 0.1, and d is The value is 0 to 0.5, and x is determined according to the valence and atomic number of each element other than O. The catalyst has large specific surface area and high activity, and can better solve the problem of low activity of the catalyst prepared by the prior art.

Description

Catalyst for preparing propylene by direct dehydrogenation of propane, preparation method and application thereof

Technical Field

The invention relates to a reaction catalyst for preparing propylene by direct dehydrogenation of propane, a preparation method and application thereof, belonging to the field of catalysis.

Background

Propylene is an important organic chemical basic raw material and is widely used for producing chemical products such as polypropylene, acrylonitrile, acrylic acid, acrolein, isopropanol, acetone, propylene oxide and the like. Currently, propylene is mainly derived from catalytic cracking of heavy oil and steam cracking of naphtha. However, the two technologies have the problems of high energy consumption, low selectivity to specific olefin and the like. With the decreasing petroleum reserves and the growing propylene demand, the search for more economical feedstocks and more efficient propylene production technologies has become a consensus in the petrochemical industry. With the improvement of the shale gas exploitation technology, the available shale gas amount is greatly increased. The shale gas contains a large amount of propane, the research on the reaction for preparing the propylene by propane dehydrogenation can improve the utilization value of the propane and relieve the increased propylene demand, and the method has important practical significance. The propane dehydrogenation processes which are now commercially available in the world are mainly the Catofin process from Lummus, the Oleflex process from UOP, the STAR process from Uhde, the FBD process from Snamprogetti-Yarsintez and the PDH process from Linde-BASF.

The catalyst with Pt element as main active component and the catalyst with Cr element as main active component are two important catalysts for the direct dehydrogenation of propane to prepare propylene. K-Cl-Ce-Pt-Sn/gamma-Al reported in Chinese patent (CN102049267B)₂O₃The catalyst has the advantages of 31.3 percent of propane conversion rate, 96.6 percent of propylene selectivity and less carbon deposition amount, but the catalyst conversion rate needs to be improved and the cost of noble metal is high. Compared with Pt-based catalysts, Cr-based catalysts are relatively cheap, so that the Cr-based catalysts are widely applied to propane dehydrogenation. Chinese patent (CN107715862A) reports Cr-K-Ca/Al₂O₃Catalyst with Cr₂O₃As an active ingredient, K₂O is used as a first auxiliary agent, CaO is used as a second auxiliary agent, the carbon deposition resistance is good, but the propane conversion rate is still to be improved.

Disclosure of Invention

According to the first aspect of the application, the catalyst for preparing propylene by directly dehydrogenating propane is provided, and the catalyst has the advantages of more reaction active centers, difficult loss of Cr active components and the like.

The catalyst for preparing propylene by direct dehydrogenation of propane comprises the following components:

A_aCr_bM_cD_dO_x；

wherein:

a is at least one of Zn, Mn, Mg, Ni and Co; preferably Zn;

m is at least one of alkali metals; the alkali metal is selected from at least one of lithium, sodium, potassium, rubidium and cesium;

d consists of Cu and Ce;

the value of a is 0.01-0.5, the value of b is 1-10, the value of c is 0.002-0.1, the value of d is 0-0.5, and x is determined according to the valence and the atomic number of each element except O; for example, if all of the metals A, Cr, M and D have a valence of +2, x is a + b + c + D.

Wherein, the upper limit of a can be selected from 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03 or 0.02, and the lower limit can be selected from 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02 or 0.01;

the upper limit of the value of b can be selected from 10, 9, 8, 7, 6, 5, 4, 3 or 2, and the lower limit can be selected from 9, 8, 7, 6, 5, 4, 3, 2 or 1;

c can have an upper limit selected from 0.1, 0.05, 0.01, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004 or 0.003 and a lower limit selected from 0.05, 0.01, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004, 0.003 or 0.002;

the upper limit of d can be selected from 0.5, 0.4, 0.3, 0.2 or 0.1, and the lower limit is selected from 0.4, 0.3, 0.2, 0.1 or 0.

Optionally, the molar ratio of A to Cr is (0.001-0.5): 1.

alternatively, the upper limit of the molar ratio of a to Cr may be selected from 0.5:1, 0.4:1, 0.3:1, 0.2:1, 0.1:1, or 0.01:1, and the lower limit may be selected from 0.4:1, 0.3:1, 0.2:1, 0.1:1, 0.01:1, or 0.001: 1.

optionally, the molar ratio of A to Cr is (0.1-0.5): 1.

optionally, the molar ratio of Cu to Ce in D is (0.01-0.02): 1.

in one embodiment, a is 0.1 to 0.5; b is 1-10; c is 0.002-0.1; d is 0-0.3.

According to a second aspect of the present application, there is provided a method for preparing a catalyst for direct dehydrogenation of propane to propylene, the method comprising the steps of:

(1) mixing the mixed solution dissolved with the Cr salt, the A salt and the D salt with an alkali solution for precipitation, filtering, drying and roasting to obtain a catalyst intermediate;

(2) impregnating the catalyst intermediate by using a salt solution containing M ions, drying and roasting to obtain A_aCr_bM_cD_dO_xA catalyst.

Optionally, the Cr salt, the A salt and the D salt are selected from at least one of chloride, nitrate, oxalate and acetate of corresponding metal;

preferably, one selected from nitrates or acetates of the corresponding metals.

Optionally, in the mixed solution, the molar ratio of the element A to the Cr is (0.001-0.5): 1; the molar ratio of the elements Cu and Ce is (0.01-0.02): 1.

optionally, the alkali solution is selected from an aqueous solution of at least one of ammonia, ammonium carbonate, ammonium bicarbonate, sodium carbonate.

Optionally, the total mass concentration of the metal ions in the mixed solution is 0.1-2 mol/L; the mass concentration of the alkali molecules in the alkali solution is 0.1-2 mol/L.

Alternatively, the amount concentration of the total species of the metal ions in the mixed solution and the upper limit of the species of the alkali in the alkali solution may be each selected from 2mol/L, 1.5mol/L, 1mol/L, 0.9mol/L, 0.8mol/L, 0.7mol/L, 0.6mol/L, 0.5mol/L, 0.4mol/L, 0.3mol/L, or 0.2mol/L, and the lower limit may be each selected from 1.5mol/L, 1mol/L, 0.9mol/L, 0.8mol/L, 0.7mol/L, 0.6mol/L, 0.5mol/L, 0.4mol/L, 0.3mol/L, 0.2mol/L, or 0.1 mol/L.

Preferably, the total mass concentration of the metal ions in the mixed solution is 0.5-1.2 mol/L; the mass concentration of the alkali in the alkali solution is 0.5-1.2 mol/L.

Alternatively, the concentration of the total mass of metal ions in the mixed solution and the concentration of the mass of alkali molecules in the alkali solution may be the same or different, preferably the same or substantially the same.

Optionally, the mixed precipitation in step (1) specifically includes the following conditions:

the mixed precipitation mode is cocurrent precipitation;

the precipitation temperature is 50-90 ℃; preferably 60-80 ℃;

the pH value of the precipitate is 6.5-9.0; preferably 7.0 to 7.5.

Optionally, the impregnation of the catalyst intermediate with the M ion-containing salt solution of step (2) comprises:

firstly, reducing the catalyst intermediate by adopting an alkali metal borohydride solution;

impregnating the reduced catalyst intermediate.

Wherein the alkali metal borohydride is preferably NaBH₄；

By using NaBH₄The catalyst intermediate is treated to improve the disordered distribution degree of catalyst ions, so that the surface defects and oxygen vacancy content of the catalyst are increased, the adsorption of reactants is facilitated, and the activity of the catalyst is further improved.

Optionally, the mass concentration of the alkali metal borohydride solution is 0.5-1%;

the mass ratio of the alkali metal borohydride to the catalyst intermediate is 0.1-0.2.

Optionally, the conditions of the reduction treatment include:

the treatment temperature is 0-20 ℃;

the treatment time is 1-4 h.

Optionally, the drying temperature in the step (1) and the drying temperature in the step (2) can be the same or different, and the drying time can be the same or different, wherein the roasting temperature is within the range of 80-150 ℃, and the drying time is 10-36 h;

the roasting temperature in the step (1) and the roasting time in the step (2) can be the same or different, wherein the roasting temperature is 400-800 ℃, and the roasting time is 1-6 h.

In one embodiment, the preparation method of the catalyst comprises the following steps:

(1) weighing a proper amount of soluble chromium salt and soluble salts of elements A and D, dissolving the soluble salts into deionized water to prepare a mixed salt solution, weighing a proper amount of alkali, and dissolving the alkali into the deionized water to prepare an alkali solution;

(2) carrying out cocurrent precipitation on the two aqueous solutions at a certain temperature and under a certain pH condition, and then aging, filtering, drying and roasting to obtain a catalyst intermediate;

(3) with NaBH₄Reducing the catalyst intermediate with solution, loading the catalyst intermediate with a proper amount of soluble salt of element M, drying, and calcining to obtain A_aCr_bM_cD_dO_xA catalyst.

Optionally, a is one of Zn, Mn, Mg, Ni, and Co; m is at least one of alkali metals; and D is a mixture of Cu and Ce.

Optionally, the soluble salt of elements A, Cr and D is one of metal-chloride, nitrate, oxalate, acetate, preferably one of metal nitrate or acetate.

Optionally, in the preparation process of the salt solution, the molar ratio of the element A to the Cr is (0.001-0.5): 1.

optionally, in the preparation process of the salt solution, the ratio of Cu to Ce in the element D is (0.01-0.02): 1.

optionally, the alkali is one or more of ammonia water, ammonium carbonate, ammonium bicarbonate and sodium carbonate, preferably ammonium carbonate.

Optionally, the quantity concentration of total metal ions in the salt solution and the quantity concentration of alkali solution in the preparation process of the salt solution and the alkali solution are kept to be substantially the same, and are within the range of 0.1-2 mol/L, and preferably 0.5-1.2 mol/L.

Alternatively, the precipitation process is carried out under the condition of water bath, and the pH value in the precipitation process is controlled by adjusting the flow rates of the salt solution and the alkali solution under the stirring condition of a stirring paddle. Specifically, the temperature of the water bath is 50-90 ℃, and the preferred temperature is 60-80 ℃; the pH value is 6.5 to 9.0, preferably 7.0 to 7.5.

Optionally, the drying process is drying the obtained solid at 80-150 ℃, preferably 100 ℃; drying for 10-36h, preferably 12 h.

Optionally, the roasting process refers to roasting the dried solid at 400-800 ℃, preferably 450-600 ℃; specifically, the temperature is raised to 150 ℃ at the temperature rise rate of 2 ℃/min, the temperature is maintained for 2h, the temperature is raised to 350 ℃ at the temperature rise rate of 2 ℃/min, the temperature is maintained for 2h, the temperature is raised to 600 ℃ at the temperature rise rate of 2 ℃/min, and the roasting is carried out for 1 to 6h, preferably 2 to 4 h.

Alternatively, with NaBH₄The solution reduction treatment of the catalyst intermediate is carried out at 0-20 ℃, and the treatment is carried out for 1-4h, preferably 2 h.

Alternatively, soluble salts of the element M are used as raw materials, and the element M is loaded by an impregnation mode, and preferably nitrate.

According to a third aspect of the present application, there is provided a method for producing propylene by direct dehydrogenation of propane, comprising passing a feed gas containing propane through a reactor, and contacting and reacting with at least one of the catalyst described in any one of the above and the catalyst produced by any one of the above methods to produce propylene.

Alternatively, the specific conditions of the contact reaction include:

the reaction temperature is 400-700 ℃;

the reaction pressure is 0-3.0 MPa;

the mass space velocity of the propane is 1500-100000 ml/(g × h); the volume percentage of propane in the feed gas is 5-100%.

Optionally, the feed gas further comprises at least one of nitrogen, argon, helium, and hydrogen.

Optionally, the reactor is selected from one of a fixed bed, moving bed or fluidized bed reactor.

In a specific embodiment, a method for preparing propylene by direct dehydrogenation of propane comprises the following steps:

passing a raw material gas containing propane through a reactor, contacting with any one of the catalysts and the catalyst prepared by any one of the methods, and reacting to generate propylene, byproduct methane, ethane, ethylene and C4 hydrocarbon.

Optionally, the reaction temperature is 400-700 ℃, the reaction pressure is 0-5.0 MPa, the mass space velocity of propane is 1500-100000 ml/(g × h), and the volume percentage of propane in the feed gas is 5-100%.

Optionally, the upper limit of the reaction temperature is selected from the group consisting of 410 ℃, 420 ℃, 450 ℃, 480 ℃, 500 ℃, 550 ℃, 580 ℃, 600 ℃, 630 ℃, 650 ℃, 680 or 700 ℃; the lower limit is selected from 400 deg.C, 420 deg.C, 450 deg.C, 480 deg.C, 500 deg.C, 550 deg.C, 580 deg.C, 600 deg.C, 630 deg.C, 650 deg.C, or 680 deg.C.

Alternatively, the upper limit of the reaction pressure is selected from 0.1MPa, 0.2MPa, 0.5MPa, 0.8MPa, 1.0MPa, 1.2MPa, 1.5MPa, 2.0MPa, 2.2MPa, 2.5MPa, 2.8MPa, 3.0MPa, 3.2MPa, 3.5MPa, 3.8MPa, 4.0MPa, 4.2MPa, 4.5MPa, 4.8MPa or 5.0 MPa;

the lower limit is selected from 0.1MPa, 0.2MPa, 0.5MPa, 0.8MPa, 1.0MPa, 1.2MPa, 1.5MPa, 1.8MPa, 2.0MPa, 2.2MPa, 2.5MPa, 2.8MPa, 3.0MPa, 3.2MPa, 3.5MPa, 3.8MPa, 4.0MPa, 4.2MPa, 4.5MPa or 4.8 MPa.

Optionally, the upper limit of the propane mass space velocity is selected from 1600ml/(g h), 2000ml/(g h), 3000ml/(g h), 5000ml/(g h), 7000ml/(g h), 8000ml/(g h), 10000ml/(g h), 20000ml/(g h), 30000ml/(g h), 40000ml/(g h), 50000ml/(g h), 80000ml/(g h) or/100000 ml/(g h); the lower limit is selected from 1500ml/(g h), 1600ml/(g h), 2000ml/(g h), 3000ml/(g h), 5000ml/(g h), 7000ml/(g h), 8000ml/(g h), 10000ml/(g h), 20000ml/(g h), 30000ml/(g h), 40000ml/(g h), 50000ml/(g h), 80000ml/(g h) or 90000ml/(g h).

The feed gas can also contain any one or a mixture of any several of nitrogen, argon, helium and hydrogen;

the reactor may be one of a fixed bed, moving bed or fluidized bed reactor.

Further, the reaction temperature is preferably 480 to 600 ℃.

Further, the reaction pressure is preferably 0 to 1.0 MPa.

Further, the reaction space velocity is preferably 3000-10000 ml/(g × h).

The operating conditions of the propane volume content in the raw material gas, the reaction temperature, the reaction pressure, the space velocity and the like can be selected by those skilled in the art according to actual needs.

Benefits of the present application include, but are not limited to:

(1) the invention provides a catalyst for preparing propylene by propane dehydrogenation, which has the advantages of more reaction active centers, difficult loss of Cr active components and the like.

(2) The invention provides a catalyst for preparing propylene by propane dehydrogenation, which has the advantages of large specific surface area, high dispersibility of active components, high reaction activity of the catalyst and the like.

(3) The invention provides a catalyst for preparing propylene by propane dehydrogenation, wherein the addition of an element M effectively regulates the acidity-basicity and electronic properties of the surface of the catalyst, and obviously improves the selectivity of a target product.

(4) The invention provides a preparation method of a catalyst for preparing propylene by propane dehydrogenation, which uses NaBH₄The treatment of the catalyst intermediate increases the defect sites on the surface of the catalyst, further improving the activity of the catalyst.

(5) The catalyst is applied to the reaction of preparing propylene by propane dehydrogenation, not only can ensure high product yield, but also has wide adjustable range of reaction process conditions, so that the catalyst has universality and extremely wide industrial application range.

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 raw materials and the products were detected by Agilent 7890B gas chromatography from Agilent, Inc., using PLOT-Q capillary column from Agilent, Inc.

In the examples of the present application, both propane conversion and propylene selectivity were calculated on a carbon mole basis.

The conversion, selectivity, in the examples of the present application were calculated as follows:

propane conversion ═ [ (moles of propane carbon in feed) - (moles of propane carbon in discharge) ]/(moles of propane carbon in feed) × (100%)

Propylene selectivity [ moles of propylene carbon in the discharge ]/[ (moles of propane carbon in the feed) - (moles of propane carbon in the discharge) ] × (100%)

The specific surface area measurement method in the application is as follows:

obtained by physical adsorption of nitrogen at a temperature of 77K using a Micromeritics ASAP2020 type physical adsorption apparatus.

Example 1 Zn_0.5Cr₂Cs_0.002O_xPreparation of the catalyst

Weighing 0.05mol of zinc nitrate and 0.2mol of chromium nitrate, and dissolving with 250mL of deionized water to obtain a water solution I; weighing 0.25mol of ammonium carbonate, and dissolving the ammonium carbonate in 250mL of water to obtain a water solution II; and (3) performing co-current co-precipitation on the aqueous solution I and the aqueous solution II under the conditions of water bath at 70 ℃ and stirring of a stirring paddle, and controlling the pH value in precipitation to be 7.0-7.5. And after coprecipitation, aging at 70 ℃ for 3h, filtering and washing, drying at 100 ℃ for 12h, and roasting at 500 ℃ for 3h to obtain a catalyst intermediate. After the completion of calcination, 0.0002mol of cesium nitrate was loaded on the catalyst intermediate by an equal volume impregnation method, dried at 100 ℃ for 12 hours, and calcined at 500 ℃ for 2 hours to obtain Zn_0.5Cr₂Cs_0.002O_xA catalyst.

Example 2 Zn_0.5Cr₂Cs_0.02O_xPreparation of the catalyst

Mixing with sodium sulfateThe cesium acid was changed to 0.002mol and all preparation procedures were in accordance with example 1. Obtaining Zn_0.5Cr₂Cs_0.02O_xA catalyst.

Example 3 Zn_0.5Cr₂Cs_0.1O_x

Cesium nitrate was changed to 0.01mol and all preparation procedures were in accordance with example 1. Obtaining Zn_0.5Cr₂Cs_0.1O_xA catalyst.

Example 4 Zn_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xPreparation of the catalyst

Weighing 0.2mol of zinc nitrate, 0.6mol of chromium nitrate, 0.1mol of cerium nitrate and 0.001mol of copper nitrate, and dissolving with 900mL of deionized water to obtain a water solution I; weighing 0.9mol of ammonium carbonate, and dissolving in 900mL of water to obtain a water solution II; and (3) performing co-current co-precipitation on the aqueous solution I and the aqueous solution II under the conditions of water bath at 70 ℃ and stirring of a stirring paddle, and controlling the pH value in precipitation to be 7.0-7.5. And after coprecipitation, aging at 70 ℃ for 3h, filtering and washing, drying at 100 ℃ for 12h, and roasting at 500 ℃ for 3h to obtain a catalyst intermediate. After the completion of roasting, NaBH with mass concentration of 1% is used under the condition of ice bath₄Reducing the catalyst intermediate with aqueous solution for 1h, wherein NaBH₄The mass ratio of the obtained product to the catalyst intermediate is 0.2, after centrifugal washing and drying, 0.005mol of cesium nitrate is loaded on the reduced catalyst intermediate by an isometric immersion method, drying is carried out for 12h at 100 ℃, and roasting is carried out for 2h at 500 ℃ to obtain Zn_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xA catalyst. The specific surface area of the catalyst is shown in Table 1.

Example 5 Mn_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xPreparation of the catalyst

The zinc nitrate was replaced by manganese nitrate and all preparation procedures were in accordance with example 4. Obtaining Mn_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xA catalyst. The specific surface area of the catalyst is shown in Table 1.

Example 6 Mg_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xPreparation of the catalyst

The zinc nitrate was replaced by magnesium nitrate and all preparation procedures were in accordance with example 4. Obtaining Mg_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xA catalyst. The specific surface area of the catalyst is shown in Table 1.

Example 7 Co_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xPreparation of the catalyst

The zinc nitrate was replaced by cobalt nitrate and all preparation procedures were in accordance with example 4. To obtain Co_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xA catalyst. The specific surface area of the catalyst is shown in Table 1.

TABLE 1 specific surface area of catalyst

Catalyst and process for preparing same	Specific surface area (m)²/g)	Pore volume (cm)³/g)
			Example 4	148.4	0.294
Example 5	85.3	0.190
			Example 6	110.5	0.247
Example 7	96.0	0.211

As is clear from Table 1, when A is Zn, the specific surface area of the catalyst is the largest at the same ratio.

Example 8 Zn_0.01Cr₁₀Cs_0.005Cu_0.01Ce_0.5O_xPreparation of the catalyst

Weighing 0.001mol of zinc nitrate, 1mol of chromium nitrate, 0.05mol of cerium nitrate and 0.001mol of copper nitrate, and dissolving with 1000mL of deionized water to obtain a water solution I; weighing 1mol of ammonium carbonate, and dissolving the ammonium carbonate in 1000mL of water to obtain a water solution II; and (3) performing co-current co-precipitation on the aqueous solution I and the aqueous solution II under the conditions of water bath at 70 ℃ and stirring of a stirring paddle, and controlling the pH value in precipitation to be 7.0-7.5. And after coprecipitation, aging at 70 ℃ for 3h, filtering and washing, drying at 100 ℃ for 12h, and roasting at 500 ℃ for 3h to obtain a catalyst intermediate. After the completion of roasting, NaBH with mass concentration of 1% is used under the condition of ice bath₄Reducing the catalyst intermediate with aqueous solution for 1h, wherein NaBH₄The mass ratio of the obtained product to the catalyst intermediate is 0.2, after centrifugal washing and drying, 0.0005mol of cesium nitrate is loaded on the reduced catalyst intermediate by an isometric immersion method, drying is carried out for 12h at 100 ℃, and roasting is carried out for 2h at 500 ℃ to obtain Zn_0.01Cr₁₀Cs_0.005Cu_0.01Ce_0.5O_xA catalyst.

Example 9 Zn_0.06Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xPreparation of the catalyst

Weighing 0.06mol of zinc nitrate, 0.6mol of chromium nitrate, 0.1mol of cerium nitrate and 0.001mol of copper nitrate, and dissolving with 760mL of deionized water to obtain a water solution I; weighing 0.76mol of ammonium carbonate, and dissolving in 760mL of water to obtain a water solution II; and (3) performing co-current co-precipitation on the aqueous solution I and the aqueous solution II under the conditions of water bath at 70 ℃ and stirring of a stirring paddle, and controlling the pH value in precipitation to be 7.0-7.5.And after coprecipitation, aging at 70 ℃ for 3h, filtering and washing, drying at 100 ℃ for 12h, and roasting at 500 ℃ for 3h to obtain a catalyst intermediate. After the completion of the calcination, NaBH with a mass concentration of 0.75% is used under the ice-bath condition₄Reducing the catalyst intermediate with aqueous solution for 1h, wherein NaBH₄The mass ratio of the obtained product to the catalyst intermediate is 0.15, the obtained product is centrifugally washed and dried, 0.005mol of cesium nitrate is loaded on the reduced catalyst intermediate by an isometric immersion method, the obtained product is dried at 100 ℃ for 12h and roasted at 500 ℃ for 2h to obtain Zn_0.06Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xA catalyst.

Example 10 Zn_0.3Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xPreparation of the catalyst

Weighing 0.3mol of zinc nitrate, 0.6mol of chromium nitrate, 0.1mol of cerium nitrate and 0.001mol of copper nitrate, and dissolving with 1000mL of deionized water to obtain a water solution I; weighing 1mol of ammonium carbonate, dissolving the ammonium carbonate in 1000mL of water to obtain an aqueous solution II, carrying out co-current co-precipitation on the aqueous solution I and the aqueous solution II under the conditions of water bath at 70 ℃ and stirring of a stirring paddle, and controlling the pH value in precipitation to be 7.0-7.5. And after coprecipitation, aging at 70 ℃ for 3h, filtering and washing, drying at 100 ℃ for 12h, and roasting at 500 ℃ for 3h to obtain a catalyst intermediate. After the completion of the calcination, NaBH with a mass concentration of 0.5% is used under the ice-bath condition₄Reduction treatment with aqueous solution for 1h, wherein NaBH is added₄The mass ratio of the obtained product to the catalyst intermediate is 0.1, the obtained product is centrifugally washed and dried, 0.005mol of cesium nitrate is loaded on the reduced catalyst intermediate by an isometric immersion method, the obtained product is dried at 100 ℃ for 12h and roasted at 500 ℃ for 2h to obtain Zn_0.3Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xA catalyst.

Example 11 Zn_0.3Cr_1.5K_0.1Cu_0.004Ce_0.3O_xPreparation of the catalyst

Weighing 0.3mol of zinc nitrate, 1.5mol of chromium nitrate, 0.3mol of cerium nitrate and 0.004mol of copper nitrate, and dissolving with 2100mL of deionized water to obtain a water solution I; 2.1mol of ammonium carbonate are weighed out and dissolved in 2100mL of waterObtaining an aqueous solution II; and co-current co-precipitating the two aqueous solutions in a water bath at 70 ℃ under the stirring condition of a stirring paddle, and controlling the pH value in precipitation to be 7.0-7.5. And after coprecipitation, aging at 70 ℃ for 3h, filtering and washing, drying at 100 ℃ for 12h, and roasting at 500 ℃ for 3h to obtain a catalyst intermediate. After the completion of the calcination, NaBH with a mass concentration of 0.75% is used under the ice-bath condition₄Reducing the catalyst intermediate with aqueous solution for 1h, wherein NaBH₄The mass ratio of the catalyst to the intermediate was 0.15, and after centrifugal washing and drying, 0.1mol of potassium nitrate was loaded on the reduced catalyst intermediate by an isometric immersion method, dried at 100 ℃ for 12 hours, and calcined at 500 ℃ for 2 hours to obtain Zn_0.3Cr_1.5K_0.1Cu_0.004Ce_0.3O_xA catalyst.

Example 12 Zn_0.3Cr_1.5Na_0.1Cu_0.004Ce_0.3O_xPreparation of the catalyst

The potassium nitrate was replaced with sodium carbonate and all preparation procedures were the same as in example 11. Obtaining Zn_0.3Cr_1.5Na_0.1Cu_0.004Ce_0.3O_xA catalyst.

Example 13 Zn_0.3Cr_1.5Cs_0.05K_0.05Cu_0.004Ce_0.3O_xPreparation of the catalyst

The catalyst intermediate was prepared in the same manner as in example 11. Using NaBH in ice bath condition₄Reducing the catalyst intermediate with an aqueous solution for 1h, centrifugally washing and drying, loading 0.05mol of cesium nitrate and 0.05mol of potassium nitrate on the reduced catalyst intermediate by an isometric immersion method, drying at 100 ℃ for 12h, and calcining at 500 ℃ for 2h to obtain Zn_0.3Cr_1.5Cs_0.05K_0.05Cu_0.004Ce_0.3O_xA catalyst.

Example 14 Zn_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xPreparation of the catalyst

The preparation method was the same as that of example 4, except that cesium nitrate was directly supported by an isometric impregnation method after obtaining the catalyst intermediate.

Comparative example

0.7mol of zinc nitrate and 0.3mol of chromium nitrate are weighed, dissolved in 1000mL of distilled water, then 3mol of NaOH is dissolved in 1000mL of water, the two aqueous solutions are subjected to co-current and co-precipitation, aged at 80 ℃ for 3h, filtered, dried at 100 ℃ overnight, and roasted at 400 ℃ for 10 h. After completion of calcination, the catalyst intermediate was loaded with 0.03mol of K₂CO₃Drying at 80 ℃ overnight, and roasting at 400 ℃ for 10h to obtain Zn_0.7Cr_0.3K_0.06O_xA catalyst.

Example 15

The catalysts of the above examples 1 to 14 and comparative examples were examined for their performance under the following conditions.

0.3g of the catalyst was weighed into a stainless fixed bed reaction tube, and propane gas (propane:

argon volume ratio 10:90), the dehydrogenation reaction of propane was carried out at 500 deg.c, normal pressure and mass space velocity of propane of 6000ml/(g × h), and the reaction results are shown in table 2.

TABLE 2 reaction results of the catalysts

Example 16

The reaction result of propane dehydrogenation to propylene under different reaction temperatures

Four stainless steel fixed bed reaction tubes were packed with 0.3g of Zn as provided in example 4_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xIntroducing propane gas (volume ratio: propane: argon: 10:90), and carrying out propane dehydrogenation reaction under reaction conditions to prepare propylene;

wherein the reaction pressure in the four reaction tubes is normal pressure, the propane mass space velocity is 6000ml/(g × h), the reaction temperature is 500, 550 ℃, 600 ℃ and 650 ℃, and the reaction results are shown in Table 3.

TABLE 3 reaction results of propane dehydrogenation to propylene at different temperatures

Example 17

The reaction result of propane dehydrogenation to propylene under different reaction pressures

Three stainless steel fixed bed reaction tubes were packed with 0.3g of Zn as provided in example 4_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xIntroducing propane gas (propane: argon: 10:90), and carrying out propane dehydrogenation reaction under reaction conditions to prepare propylene;

the reaction temperature in each of the three reaction tubes was 500 ℃, the propane mass space velocity was 6000ml/(g × h), the reaction pressure was 0.1MPa, 0.5MPa, 1MPa, respectively, and the reaction results are shown in Table 4.

TABLE 4 reaction results for dehydrogenation of propane to propylene at different reaction pressures

Example 18

0.3g of Zn is weighed_0.2Cr_0.6Cs_0.005Cu_0.001Ce_0.1O_xThe resulting mixture was placed in a stainless fixed bed reaction tube, and propane gas (propane: hydrogen: argon: 10:80) was introduced to conduct dehydrogenation reaction of propane at a reaction temperature of 550 ℃, a reaction pressure of normal pressure, and a mass space velocity of 6000ml/(g × h), and the reaction results are shown in table 2.

As can be seen from tables 2 to 4, in the reaction of preparing propylene by propane dehydrogenation, the conversion rate of propane can reach 62.5% at most, the selectivity of propylene can reach more than 76.5% at most and can reach 93.5% at most; the highest propylene yield of the catalyst provided in the embodiment 4 can reach 48.62%, and when the reaction temperature is 600-650 ℃, the propylene yield can reach more than 47%.

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.

Claims

1. The catalyst for preparing the propylene by the direct dehydrogenation of the propane is characterized by comprising the following components:

A_aCr_bM_cD_dO_x；

wherein:

a is at least one of Zn, Mn, Mg, Ni and Co;

m is at least one of alkali metals;

d consists of Cu and Ce;

the value of a is 0.01-0.5, the value of b is 1-10, the value of c is 0.002-0.1, the value of d is 0-0.5, and x is determined according to the valence and the atomic number of other elements except O.

2. The catalyst for direct dehydrogenation of propane to produce propylene according to claim 1, wherein the molar ratio of a to Cr is (0.001-0.5): 1;

preferably, the molar ratio of A to Cr is (0.1-0.5): 1;

preferably, the molar ratio of Cu to Ce in D is (0.01-0.02): 1.

3. the method for preparing a catalyst for direct dehydrogenation of propane to propylene according to claim 1 or 2, comprising the steps of:

4. The method for preparing a catalyst according to claim 3, wherein the Cr salt, A salt and D salt are selected from at least one of chlorides, nitrates, oxalates and acetates of the corresponding metals;

preferably, one selected from nitrates or acetates of the corresponding metals.

5. The method for preparing a catalyst according to claim 3, wherein the molar ratio of the element A to the Cr in the mixed solution is (0.001 to 0.5): 1; the molar ratio of the elements Cu and Ce is (0.01-0.02): 1.

6. the method for preparing a catalyst according to claim 3, wherein the alkali solution is selected from an aqueous solution of at least one of ammonia, ammonium carbonate, ammonium bicarbonate, and sodium carbonate; the total mass concentration of the metal ions in the mixed solution is 0.1-2 mol/L; the mass concentration of alkali molecules in the alkali solution is 0.1-2 mol/L;

preferably, the amount concentration of the total substance of the metal ions in the mixed solution is the same as the amount concentration of the substance of the alkali molecules in the alkali solution.

7. The method for preparing the catalyst according to claim 3, wherein the mixed precipitation in the step (1) specifically comprises the following conditions:

the mixed precipitation mode is cocurrent precipitation;

the precipitation temperature is 50-90 ℃;

the pH value of the precipitate is 6.5-9.0.

8. The method for preparing a catalyst according to claim 3, wherein the impregnation of the catalyst intermediate with the salt solution containing M ions in the step (2) comprises:

impregnating the reduced catalyst intermediate;

optionally, the alkali metal borohydride is sodium borohydride, and the mass concentration of the alkali metal borohydride solution is 0.5-1%;

the mass ratio of the alkali metal borohydride to the catalyst intermediate is 0.1-0.2;

preferably, the conditions of the reduction treatment include:

the treatment temperature is 0-20 ℃;

the treatment time is 1-4 h;

preferably, the drying temperature in the step (1) and the drying temperature in the step (2) are both within the range of 80-150 ℃, and the drying time is both 10-36 h;

the roasting temperature in the step (1) and the roasting time in the step (2) are both within the range of 400-800 ℃, and the roasting time is 1-6 h.

9. A method for preparing propylene by direct dehydrogenation of propane, characterized in that a feed gas containing propane is passed through a reactor and is subjected to a contact reaction with at least one of the catalyst of claim 1 or 2 and the catalyst prepared by the method of any one of claims 3 to 8 to produce propylene.

10. The method according to claim 9, wherein the specific conditions of the contact reaction comprise:

the reaction temperature is 400-700 ℃;

the reaction pressure is 0-3.0 MPa;

the mass space velocity of the propane is 1500-100000 ml/(g × h); the volume percentage content of propane in the feed gas is 5-100%;

preferably, the feed gas further comprises at least one of nitrogen, argon, helium and hydrogen.