CN115501871A

CN115501871A - Propane dehydrogenation catalyst and preparation method and application thereof

Info

Publication number: CN115501871A
Application number: CN202110700054.9A
Authority: CN
Inventors: 吴省; 洪学思; 缪长喜; 宋磊
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Priority date: 2021-06-23
Filing date: 2021-06-23
Publication date: 2022-12-23
Anticipated expiration: 2041-06-23
Also published as: CN115501871B

Abstract

The invention discloses a propane dehydrogenation catalyst and a preparation method and application thereof. The catalyst comprises: alumina containing IVB group elements is used as a carrier, cr or an oxide thereof is used as an active component, and IA group and/or IIA group elements or an oxide thereof is used as an auxiliary component; wherein the catalyst has alloy peaks of IVB group elements and Cr element as active component in 380-580 deg.c, which is measured by TPR test. The catalyst is suitable for propane dehydrogenation reaction, and mainly solves the problems of low activity and stability of the catalyst prepared by the prior art.

Description

Propane dehydrogenation catalyst and preparation method and application thereof

Technical Field

The invention belongs to the field of petrochemical industry, and particularly relates to a catalyst for preparing propylene by propane dehydrogenation, a preparation method of the catalyst, and application of the catalyst in preparing propylene by propane dehydrogenation.

Background

Propylene is used as an important chemical raw material and can be used for producing polypropylene, acrylonitrile, propylene oxide, acrylic acid, isopropanol and the like. Propylene is mainly derived from steam cracking and catalytic cracking byproducts, but the propylene is limited by the main production of ethylene and gasoline and diesel oil, the yield is increased in a limited manner, and the demand of polypropylene is still in a rising trend, so that the method for preparing propylene by dehydrogenation reaction by using propane as a raw material is vigorously developed in various countries in the world. The propane dehydrogenation reaction is a strong endothermic reaction and is limited by thermodynamic equilibrium, so that a relatively ideal propylene yield can be obtained under the conditions of low pressure and high temperature, and the problems of poor catalyst performance, low selectivity and the like caused by the aggravation of propane cracking reaction and deep dehydrogenation due to excessively high reaction temperature.

The catalyst system adopted by the propane dehydrogenation technology mainly comprises a Pt catalyst and a Cr catalyst. The Pt catalyst is used for dehydrogenation of low-carbon alkane, has the advantages of environmental friendliness, high activity and the like, and has high price, complex preparation and high requirement on purity of reaction raw materials. The Cr series catalyst has low price, relatively high activity and low requirement on the purity of raw materials, but has certain influence on the environment, frequent regeneration is needed in the reaction process, the regeneration and other conditions are harsh, and the performance requirements on all aspects of the Cr series catalyst are higher.

CN103769156A adopts alumina treated by ammonia gas as a carrier, cr as an active component and potassium, manganese, cobalt, iron, nickel and the like as auxiliaries. The preparation method of the dehydrogenation catalyst comprises the steps of adopting ammonia gas to carry out pretreatment on an alumina carrier; the potassium and the auxiliary agent are loaded by a co-impregnation method, and then the active component chromium is impregnated and loaded. The catalyst has better selectivity, but relatively low activity. CN101940922B discloses a low-carbon alkane dehydrogenation catalyst and a preparation method thereof, wherein chromium is used as an active metal component, part of chromium is mixed with pseudo-boehmite to prepare a chromium-containing alumina carrier, and part of chromium and an auxiliary agent alkali metal are impregnated and loaded to contain chromium oxideAnd (4) preparing a dehydrogenation catalyst on an aluminum oxide carrier. The catalyst prepared by the method has the advantages that the content of active components on the outer surface of the carrier is low, the activity is low, the utilization rate of the active components in the carrier is low, and the integral stability of the catalyst is reduced after the active components on the outer surface migrate. CN103769078A discloses a catalyst for preparing olefin by low-carbon alkane dehydrogenation, and a preparation method and an application thereof. The catalyst is made of Al ₂ O ₃ The chromium is taken as a carrier, the chromium is taken as an active component, the alkali metal is taken as a promoter component, and the active component chromium is impregnated on the alumina carrier step by step before the alkali metal promoter component is impregnated and after the alkali metal promoter component is impregnated. The stability of the catalyst is still to be further improved.

At present, although the existing Cr series dehydrogenation catalysts have been greatly developed, the problems of low catalyst activity, poor stability and the like still exist.

Disclosure of Invention

The invention provides a propane dehydrogenation catalyst and a preparation method and application thereof, aiming at solving the problems of low activity and poor stability of Cr series dehydrogenation catalysts in the prior art. The catalyst is used in the process of preparing propylene by propane dehydrogenation, and has good activity and outstanding stability effect.

The present invention provides in a first aspect a propane dehydrogenation catalyst comprising: alumina containing IVB group elements is used as a carrier, cr or an oxide thereof is used as an active component, and IA group and/or IIA group elements or an oxide thereof is used as an auxiliary component; wherein the catalyst has alloy peaks of IVB group elements and Cr element as active component in 380-580 deg.c, which is measured by TPR test.

Further, the catalyst passes TPR test, and obvious alloy peaks of IVB group elements and active component Cr elements appear in the range of 380-580 ℃.

Further, the catalyst comprises the following components in parts by weight:

a) 10-30 parts of Cr element or its oxide;

b) 0.1-5 parts of auxiliary agent component, namely at least one element selected from IA group and/or IIA group elements or oxide thereof;

c) 60-90 parts of a carrier;

the carrier contains 0.1 to 5 parts of an element selected from group IVB or an oxide thereof.

Further, the group IVB element is selected from any one or two of Ti and Zr.

Further, the carrier preferably contains 0.5 to 3.0 parts of an element selected from group IVB or an oxide thereof.

Further, the IA group element is selected from any one or more of Li, na, K and Cs, preferably Na and/or K.

Further, the group IIA element is selected from any one or two of Mg and Ca.

Further, in the catalyst, the content of the auxiliary component is preferably 0.1 to 3.0 parts, and more preferably 0.1 to 2.0 parts.

Further, the alumina carrier containing the IVB group element is prepared by a mixing method, and the specific preparation process is as follows: and preparing an alumina precursor and a compound containing the IVB group element into a formed body, and drying and roasting to obtain the alumina carrier containing the IVB group element.

Furthermore, the catalyst is obtained by firstly loading part of the active component Cr on an alumina carrier containing IVB group elements, then loading the rest part of the active component Cr and an auxiliary agent component after first roasting, and then carrying out second roasting. The loading is an impregnation method, wherein the IVB group element is introduced into the carrier by a mixing method.

The second aspect of the present invention provides a method for preparing the above propane dehydrogenation catalyst, comprising:

(1) Preparing an alumina carrier containing IVB group elements, wherein the IVB group elements are introduced into the carrier by adopting a mixing method;

(2) Preparing a first Cr-containing compound and an acidic substance into an impregnation liquid I, and preparing a second Cr-containing compound and an auxiliary agent-containing compound into an impregnation liquid II;

(3) Impregnating the carrier in the step (1) with the impregnation liquid I, and performing first drying and first roasting to obtain a catalyst intermediate;

(4) And (4) impregnating the catalyst intermediate in the step (3) with the impregnation liquid II, and performing second drying and second roasting to obtain the propane dehydrogenation catalyst.

Further, the carrier in the step (1) is prepared by introducing the IVB group element into the carrier by a mixing method, and the specific preparation process is as follows: an alumina precursor (such as one or more of gibbsite, bayerite, pseudoboehmite, boehmite, diaspore and other raw materials) and a compound containing the IVB group element are prepared into a forming body, and the forming body is dried and roasted to obtain the alumina carrier containing the IVB group element. The group IVB element-containing compound may be a soluble compound such as a nitrate. The molding may be carried out by a conventional molding method such as extrusion molding, screw extrusion molding, etc. In the forming process, forming aids (such as sesbania powder, hydroxymethyl cellulose, peptizer, binder and the like) can be added. The shaping may be in a conventional shape such as a strip, a column, etc. The drying and roasting are carried out in an oxygen-containing atmosphere (such as air), and the drying conditions are as follows: the drying temperature is 80-180 ℃, and the drying time is 2-24 h. The roasting conditions are as follows: the roasting temperature is 500-900 ℃, and the roasting time is 2-12 h.

Further, in the step (2), the first Cr-containing compound and the second Cr-containing compound are each independently selected from soluble compounds, such as at least one of nitrate, sulfate, chromate.

Further, in the step (2), the acidic substance is at least one selected from nitric acid, formic acid, acetic acid, adipic acid, oxalic acid, maleic acid and the like.

Further, in the step (2), the auxiliary compound is selected from soluble compounds, wherein the group IA element-containing compound may be selected from at least one of nitrate, chloride or sulfate, and the group IIA element-containing compound may be selected from at least one of nitrate and chloride.

Further, in the step (2), the first Cr-containing compound and the acidic substance are prepared into the impregnation liquid I, wherein the mass concentration of the acidic substance is 1.5-10%, and the mass concentration of Cr is 7-30%. The impregnation solution is preferably an aqueous solution.

Further, in the step (2), a second Cr-containing compound and an auxiliary agent-containing compound are prepared into the impregnation liquid II, wherein the mass concentration of the auxiliary agent is 0.4-3.5% and the mass concentration of Cr is 5-20% in terms of elements. The impregnation solution is preferably an aqueous solution.

Further, the mass ratio of the amount of Cr introduced into the catalyst by the impregnation liquid I to the amount of Cr introduced into the catalyst by the impregnation liquid II is 1 to 3:1.

further, the impregnation in step (3) may be carried out by a conventional impregnation method, preferably by an equal volume impregnation method.

Further, the drying and calcining of the step (3) are performed under an oxygen-containing atmosphere (such as air), and the first drying conditions are as follows: the drying temperature is 80-160 ℃, the drying time is 2-24 h, and the first roasting condition is as follows: the roasting temperature is 550-800 ℃, and the roasting time is 1-10 h.

Further, the impregnation in step (4) may be carried out by a conventional impregnation method, preferably by an equal volume impregnation method.

Further, the drying and calcining of the step (4) are performed under an oxygen-containing atmosphere (such as air), and the second drying conditions are as follows: the drying temperature is 80-150 ℃, the drying time is 1-16 h, and the second roasting condition is as follows: the roasting temperature is 600-800 ℃, and the roasting time is 2-15 h.

The third aspect of the invention provides the application of the propane dehydrogenation catalyst in the preparation of propylene by propane dehydrogenation.

Further, the application process is as follows: the propane contacts with the catalyst to react to prepare the propylene.

Further, the reaction conditions were as follows: the reaction temperature is 550-620 ℃, the reaction pressure is 0.05-0.1 MPa, and the propane volume space velocity is 0.4-1.0 h ^-1 。

Compared with the prior art, the invention has the following beneficial effects:

1. the inventor has found that when the IVB group element and part of Cr exist in alloy form in the propane dehydrogenation catalyst, and then cooperate with the rest of Cr and auxiliary components, the catalyst has outstanding activity and stability. The propane dehydrogenation catalyst firstly introduces an IVB group element into a carrier by adopting a mixing method to prepare an alumina carrier containing the IVB group element, an impregnation liquid I prepared from an active component Cr part and an acidic substance is loaded on the carrier to obtain a catalyst intermediate, an impregnation liquid II prepared from the rest active component Cr and an auxiliary agent component is loaded on the catalyst intermediate, so that the active component Cr in the catalyst intermediate is fully contacted with the IVB group element in the carrier, and an alloy peak is formed under high-temperature roasting; the re-impregnated small amount of active component Cr is distributed on the outer surface of the catalyst, so that the existence of the alloy can prevent the crystal phase of partial active component Cr from transforming or migrating, and the catalyst is stabilized.

2. The propane dehydrogenation catalyst is used in the process of preparing propylene by propane dehydrogenation, the conversion rate and the selectivity of the propane dehydrogenation catalyst are basically unchanged after the reaction is carried out for 1 hour, and the conversion rate and the selectivity of the propane dehydrogenation catalyst are basically unchanged after the catalyst is repeatedly regenerated and evaluated for 200 hours.

Drawings

FIG. 1 is a TPR plot of catalyst sample 1 obtained in example 1;

FIG. 2 is a TPR plot of catalyst sample 5 obtained in example 5;

FIG. 3 is a TPR plot of sample 8 of the catalyst obtained in comparative example 1;

FIG. 4 is a TPR plot of catalyst sample 9 obtained in comparative example 2.

Detailed Description

In the invention, the TPR test is carried out by adopting AUTOCHEM II 2920 of American Mike company, and the temperature range is as follows: room temperature to 1100 ℃; the heating rate is as follows: 50 ℃/min (< 500 ℃), 30 ℃/min (500 ℃ -750 ℃); gas: h ₂ (ii) a Flow rate: 0.5-100 mL/min. In the present invention, the peak height at which the alloy peak of zirconium and the active component Cr element (denoted as peak 1) appears in the range of 380 to 580 ℃ in catalyst sample 1 obtained in example 1 was set as 100%. In the invention, the peak which is 5 percent higher than the peak height value of the peak 1 does not appear in the range of 380-580 ℃, namely the alloy peak which is obvious and does not appear in the range of 380-580 ℃ and the peak which is 5 percent higher than the peak height value of the peak 1 appears in the range of 380-580 ℃ is the alloy peak at 380-580 DEG CWithin the range, distinct alloying peaks of the group IVB element and the active component Cr element appear.

In the examples of the present invention and the comparative examples,

conversion of propane (%) = (mass of propane in reactant-mass of propane in reaction product) ÷ mass of propane in reactant × 100%;

propylene selectivity (%) = actual yield of propylene ÷ theoretical yield of propylene × 100% by mass.

In the examples of the present invention and the comparative examples, the analysis of the gas composition in the propane dehydrogenation reaction was performed on a gas chromatograph available from Agilent under the model number 7890A.

The technical solution of the present invention is described in detail with reference to the following examples, but the scope of the present invention is not limited by the examples.

Example 1

Extrusion molding of the carrier and preparation of the catalyst:

(1) Weighing 300g of boehmite and 10.5g of zirconium nitrate, and mixing the boehmite with nitric acid, sesbania powder and deionized water according to the weight ratio of 300:9:9:220, weighing corresponding raw materials, adding the raw materials into a kneader, and kneading for 30min at the rotating speed of 300 revolutions per minute of the kneader to form dough. The materials are put into a sleeve of a single-screw extruder, and a strip-shaped cylinder with the diameter phi of 3mm is extruded under the pressure of 10 MPa. And (3) placing the extruded material at room temperature for 24h, then baking the extruded material in a baking oven at 100 ℃ for 8h, and then moving the extruded material into a muffle furnace at 600 ℃ for baking for 2h to obtain a cylindrical carrier (the mass content of zirconia in the carrier is 1%) which is modified by Zr, has a diameter of 2.9-3 mm and a length of 4-6 mm.

(2) 52.65g of chromium nitrate and 2g of nitric acid were weighed and dissolved in 50g of deionized water to obtain a dipping solution I. 26.3g of chromium nitrate and 1.71g of sodium carbonate were additionally weighed and dissolved in 50g of deionized water to obtain a dipping solution II.

(3) And (3) soaking the soaking solution I in the step (2) into 100g of the roasted cylindrical carrier in the step (1), roasting in a 100 ℃ oven for 4h, and then transferring into a 600 ℃ muffle furnace for roasting for 1h to obtain a catalyst intermediate.

(4) And (3) impregnating the catalyst intermediate in the step (3) with the impregnating solution II in the step (2), putting the impregnated sample into a 150 ℃ oven for treatment for 4h, and then transferring the impregnated sample into a 600 ℃ muffle furnace for roasting for 8h to obtain a catalyst sample 1.

The TPR test result of the catalyst sample 1 is shown in FIG. 1, and an alloy peak of zirconium and an active component Cr element appears obviously in the range of 380-580 ℃.

Performance evaluation of catalyst sample 1:

the propane dehydrogenation reaction of sample 1 was carried out by the following method, and the contents of the respective components were analyzed by gas chromatography on the gas before and after the reaction. The method comprises the following steps of regulating the flow rate of pure propane gas through a mass flow meter, preheating the pure propane gas in a preheating zone, then entering a reaction zone, heating a heating section and a reaction section of a reactor by adopting electric heating wires to enable the heating section and the reaction section to reach a preset temperature, wherein the inner diameter of the reactor is a quartz tube with the phi of 12mm and the outer diameter of phi of 20mm, and the length of the quartz tube is 600mm. The reacted gas was passed through a condenser and analyzed for composition by gas chromatography. The catalyst evaluation conditions in the isothermal fixed bed reactor were as follows: 10g of catalyst is loaded into the isothermal fixed bed reactor, the reaction pressure is normal pressure, and the gas mass space velocity is 0.7h ^-1 And a reaction temperature of 580 ℃. And analyzing the content of each component by gas chromatography on the gas which reacts for 10min and 1h respectively, and calculating the conversion rate of propane and the selectivity of propylene. The catalyst evaluation results are shown in Table 1. After the catalyst reacts for 1 hour, the reaction is stopped, and then the catalyst is calcined for 2 hours at the high temperature of 650 ℃ for regeneration. The regenerated catalyst was evaluated under the same evaluation conditions as described above. The above regeneration process and evaluation process were repeated. The catalyst was evaluated for a total of 200 hours, and the results of propane conversion and propylene selectivity at 200 hours after regeneration are shown in Table 1.

Example 2

Extrusion molding of the carrier and preparation of the catalyst:

(1) Weighing 300g of gibbsite and 31.5g of zirconium nitrate, wherein the weight ratio of gibbsite to nitric acid to sesbania powder to deionized water is 300:12:12: and 230, weighing corresponding raw materials, adding the raw materials into a kneader, and kneading for 20min at the kneader rotation speed of 300 revolutions per minute to form dough. Putting the materials into a sleeve of a single-screw extruder, and extruding a strip-shaped cylinder with the diameter phi of 3mm under the pressure of 10 MPa. And (3) placing the extruded material at room temperature for 24h, baking the extruded material in an oven at 80 ℃ for 8h, and then transferring the extruded material into a muffle furnace at 600 ℃ for baking for 4h to obtain a cylindrical carrier (the mass content of zirconia in the carrier is 3%) which is modified by Zr, has a diameter of 2.9-3 mm and a length of 4-6 mm.

(2) 35.1g of chromium nitrate and 3g of nitric acid were weighed and dissolved in 50g of deionized water to obtain a dipping solution I. In addition, 17.55g of chromium nitrate and 5.13g of sodium carbonate were weighed and dissolved in 50g of deionized water to obtain a dipping solution II.

(3) And (3) soaking the soaking solution I in the step (2) into 100g of the roasted cylindrical carrier in the step (1), roasting in a 150 ℃ oven for 2h, and then transferring into a 600 ℃ muffle furnace for roasting for 2h to obtain a catalyst intermediate.

(4) And (3) dipping the catalyst intermediate in the step (3) by using the dipping solution II in the step (2), putting a dipping sample into a 150 ℃ oven for treatment for 1h, and then transferring into a 600 ℃ muffle furnace for roasting for 12h to obtain a catalyst sample 2.

As is clear from the TPR test result of the catalyst sample 2, an obvious alloy peak of zirconium and Cr element which is an active component appears in the range of 380-580 ℃.

Evaluation of the properties of catalyst sample 2: the catalyst evaluation equipment and evaluation conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 3

Extrusion molding of the carrier and preparation of the catalyst:

(1) Weighing 300g of boehmite and 5.3g of zirconium nitrate, and mixing the boehmite with nitric acid, sesbania powder and deionized water according to the weight ratio of 300:12:9:230, weighing corresponding raw materials, adding the raw materials into a kneader, and kneading at the rotating speed of 300 revolutions per minute for 10min to form dough. The materials are put into a sleeve of a single-screw extruder, and a strip-shaped cylinder with the diameter phi of 3mm is extruded under the pressure of 10 MPa. And (3) placing the extruded material at room temperature for 24h, baking the extruded material in an oven at 80 ℃ for 8h, and then transferring the extruded material into a muffle furnace at 600 ℃ for baking for 4h to obtain a cylindrical carrier (the mass content of zirconia in the carrier is 0.5%) which is modified by Zr, has a diameter of 2.9-3 mm and a length of 4-6 mm.

(2) 70.2g of chromium nitrate and 5g of nitric acid were weighed and dissolved in 50g of deionized water to obtain a dipping solution I. 35.1g of chromium nitrate and 1.37g of sodium nitrate were weighed and dissolved in 50g of deionized water to obtain immersion liquid II.

(3) And (3) soaking the soaking solution I in the step (2) into 100g of the roasted cylindrical carrier in the step (1), roasting in a 100 ℃ oven for 2h, and then transferring into a 650 ℃ muffle furnace for roasting for 2h to obtain a catalyst intermediate.

(4) And (3) dipping the catalyst intermediate in the step (3) by using the dipping solution II in the step (2), putting a dipping sample into a drying oven at 150 ℃ for treatment for 1h, and then transferring into a muffle furnace at 750 ℃ for roasting for 6h to obtain a catalyst sample 3.

As is clear from the TPR test result of the catalyst sample 3, an obvious alloy peak of zirconium and Cr which is an active component appears in the range of 380-580 ℃.

Evaluation of the properties of catalyst sample 3: the catalyst evaluation equipment and evaluation conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 4

Extrusion molding of the carrier and preparation of the catalyst:

(1) Weighing 300g of bayer and 1.1g of zirconium nitrate, and simultaneously mixing the bayer, nitric acid, sesbania powder and deionized water according to the weight ratio of 300:12:15:210, weighing corresponding raw materials, adding the raw materials into a kneader, and kneading the raw materials into a dough shape at the kneader rotation speed of 300 revolutions per minute for 30 min. Putting the materials into a sleeve of a single-screw extruder, and extruding a strip-shaped cylinder with the diameter phi of 3mm under the pressure of 10 MPa. And (3) placing the extruded material at room temperature for 24h, baking the extruded material in a baking oven at 100 ℃ for 12h, and then transferring the extruded material into a muffle furnace at 800 ℃ for baking for 8h to obtain a cylindrical carrier (the mass content of zirconia in the carrier is 0.1%) which is modified by Zr, has a diameter of 2.9-3 mm and a length of 4-6 mm.

(2) 105.3g of chromium nitrate and 5g of nitric acid were weighed and dissolved in 60g of deionized water to obtain a dipping solution I. Separately, 52.65g of chromium nitrate and 8.55g of sodium carbonate were weighed and dissolved in 50g of deionized water to obtain immersion liquid II.

(3) And (3) soaking the soaking solution I in the step (2) into 100g of the roasted cylindrical carrier in the step (1), roasting in a drying oven at 140 ℃ for 6h, and then transferring into a muffle furnace at 700 ℃ for roasting for 3h to obtain a catalyst intermediate.

(4) And (3) impregnating the catalyst intermediate in the step (3) with the impregnating solution II in the step (2), putting the impregnated sample into a 150 ℃ oven for treating for 1h, and then transferring the impregnated sample into a 800 ℃ muffle furnace for roasting for 12h to obtain a catalyst sample 4.

As is clear from the TPR test result of the catalyst sample 4, an obvious alloy peak of zirconium and Cr which is an active component appears in the range of 380-580 ℃.

Evaluation of the properties of catalyst sample 4: the catalyst evaluation equipment and evaluation conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 5

Extrusion molding of the carrier and preparation of the catalyst:

(1) Weighing 300g of boehmite and 9.0g of titanium nitrate, and mixing the boehmite with nitric acid, sesbania powder and deionized water according to the weight ratio of 300:9:9:220, weighing corresponding raw materials, adding the raw materials into a kneader, and kneading for 30min at the rotating speed of 300 revolutions per minute of the kneader to form dough. Putting the materials into a sleeve of a single-screw extruder, and extruding a strip-shaped cylinder with the diameter phi of 3mm under the pressure of 10 MPa. And (3) placing the extruded material at room temperature for 24h, baking the extruded material in a baking oven at 100 ℃ for 6h, and then transferring the extruded material into a muffle furnace at 600 ℃ for baking for 4h to obtain a cylindrical carrier (the mass content of titanium oxide in the carrier is 1%) which is modified by Ti, has a diameter of 2.9-3 mm and a length of 4-6 mm.

(2) 35.1g of chromium nitrate and 4g of nitric acid were weighed and dissolved in 50g of deionized water to obtain a dipping solution I. In addition, 17.55g of chromium nitrate and 5.13g of sodium carbonate were weighed and dissolved in 50g of deionized water to obtain impregnation liquid II.

(4) And (3) impregnating the catalyst intermediate in the step (3) with the impregnating solution II in the step (2), putting the impregnated sample into a 150 ℃ oven for treating for 1h, and then transferring the impregnated sample into a 600 ℃ muffle furnace for roasting for 12h to obtain a catalyst sample 5.

As is clear from the TPR test result of the catalyst sample 5, an obvious alloy peak of titanium and Cr element which is an active component appears in the range of 380-580 ℃.

Performance evaluation of catalyst sample 5: the catalyst evaluation apparatus and evaluation conditions were the same as in example 1, and the catalyst evaluation results are shown in table 1.

Example 6

Extrusion molding of the carrier and preparation of the catalyst:

(1) Weighing 300g of boehmite and 10.5g of zirconium nitrate, and mixing the boehmite with nitric acid, sesbania powder and deionized water according to the weight ratio of 300:9:9:220, weighing corresponding raw materials, adding the raw materials into a kneader, and kneading for 30min at the kneader rotation speed of 300 revolutions per minute to form dough. The materials are put into a sleeve of a single-screw extruder, and a strip-shaped cylinder with the diameter phi of 3mm is extruded under the pressure of 10 MPa. And (3) placing the extruded material at room temperature for 24h, baking the extruded material in a baking oven at 120 ℃ for 8h, and then transferring the extruded material into a muffle furnace at 600 ℃ for baking for 4h to obtain a cylindrical carrier (the mass content of zirconia in the carrier is 1%) which is modified by Zr, has a diameter of 2.9-3 mm and a length of 4-6 mm.

(2) 35.1g of chromium nitrate and 2g of nitric acid were weighed and dissolved in 50g of deionized water to obtain a dipping solution I. In addition, 17.55g of chromium nitrate and 2.15g of potassium nitrate were weighed and dissolved in 50g of deionized water to obtain immersion liquid II.

(3) And (3) soaking the soaking solution I in the step (2) into 100g of the roasted cylindrical carrier in the step (1), roasting in a 100 ℃ oven for 2h, and then transferring into a 550 ℃ muffle furnace for roasting for 2h to obtain a catalyst intermediate.

(4) And (3) dipping the catalyst intermediate in the step (3) by using the dipping solution II in the step (2), putting a dipped sample into a 100 ℃ oven for treatment for 4h, and then transferring into a 750 ℃ muffle furnace for roasting for 6h to obtain a catalyst sample 6.

As is clear from the TPR test result of the catalyst sample 6, an obvious alloy peak of zirconium and Cr element which is an active component appears in the range of 380-580 ℃.

Evaluation of the properties of catalyst sample 6: the catalyst evaluation equipment and evaluation conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 7

Extrusion molding of the carrier and preparation of the catalyst:

(1) Weighing 300g of boehmite and 10.5g of zirconium nitrate, and mixing the boehmite with acetic acid, sesbania powder and deionized water according to the weight ratio of 300:15:9:220, weighing corresponding raw materials, adding the raw materials into a kneader, and kneading for 30min at the rotating speed of 300 revolutions per minute of the kneader to form dough. Putting the materials into a sleeve of a single-screw extruder, and extruding a strip-shaped cylinder with the diameter phi of 3mm under the pressure of 10 MPa. And (3) placing the extruded material at room temperature for 24h, then baking the extruded material in a 120 ℃ baking oven for 8h, and then moving the extruded material into a 600 ℃ muffle furnace for baking for 4h to obtain a cylindrical carrier (the mass content of zirconia in the carrier is 1%) which is modified by Zr, has a diameter of 2.9-3 mm and a length of 4-6 mm.

(2) 35.1g of chromium nitrate and 2g of nitric acid were weighed and dissolved in 50g of deionized water to obtain a dipping solution I. In addition, 17.55g of chromium nitrate and 2.93g of calcium nitrate were weighed and dissolved in 50g of deionized water to obtain impregnation solution II.

(3) And (3) soaking the impregnation liquid I obtained in the step (2) into 100g of the roasted cylindrical carrier obtained in the step (1), roasting in a 110 ℃ oven for 4h, and then transferring into a 650 ℃ muffle furnace for roasting for 3h to obtain a catalyst intermediate.

(4) And (3) dipping the catalyst intermediate in the step (3) by using the dipping solution II in the step (2), putting a dipped sample into a 100 ℃ oven for treatment for 4h, and then transferring into a 750 ℃ muffle furnace for roasting for 6h to obtain a catalyst sample 7.

As is clear from the TPR test result of the catalyst sample 7, an obvious alloy peak of zirconium and Cr which is an active component appears in the range of 380-580 ℃.

Performance evaluation of catalyst sample 7: the catalyst evaluation equipment and evaluation conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Comparative example 1

Coprecipitation preparation and forming of a carrier and preparation of a catalyst:

(1) Mixing 1000g of alumina sol with the solid content of 30% and 10.5g of zirconium nitrate to prepare a mixture I, carrying out cocurrent flow precipitation on the mixture I and ammonia water, controlling the pH value to be 9, washing after the precipitation is finished, and drying in a drying oven at 100 ℃ for 8h to obtain a dried substance. The dried substance, nitric acid, sesbania powder and deionized water are added into a kneader according to the proportion of the embodiment 1, the rotation speed of the kneader is 300 r/min, and the kneading time is 30min, so that the dough is formed. Putting the materials into a sleeve of a single-screw extruder, and extruding a strip-shaped cylinder with the diameter phi of 3mm under the pressure of 10 MPa. And (3) placing the extruded material at room temperature for 24h, then baking the extruded material in a baking oven at 100 ℃ for 8h, and then moving the extruded material into a muffle furnace at 600 ℃ for baking for 2h to obtain a cylindrical carrier (the mass content of zirconia in the carrier is 1%) which is modified by Zr, has a diameter of 2.9-3 mm and a length of 4-6 mm.

(2) 52.65g of chromium nitrate and 2g of nitric acid were weighed and dissolved in 50g of deionized water to obtain a dipping solution I. 26.3g of chromium nitrate and 1.71g of sodium carbonate were weighed and dissolved in 50g of deionized water to obtain immersion liquid II.

(4) And (3) dipping the catalyst intermediate in the step (3) by using the dipping solution II in the step (2), putting a dipping sample into a 150 ℃ oven for treatment for 4h, and then transferring into a 600 ℃ muffle furnace for roasting for 8h to obtain a catalyst sample 8.

The TPR test result from catalyst sample 8 is shown in FIG. 2, and no significant peak appears in the range of 380 to 580 ℃.

Evaluation of the properties of catalyst sample 8: the catalyst evaluation equipment and evaluation conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Comparative example 2

Extrusion molding of the carrier and preparation of the catalyst:

(1) Weighing 300g of boehmite, and mixing the boehmite with nitric acid, sesbania powder and deionized water according to the weight ratio of 300:9:9:220, weighing corresponding raw materials, adding the raw materials into a kneader, and kneading for 30min at the rotating speed of 300 revolutions per minute of the kneader to form dough. The materials are put into a sleeve of a single-screw extruder, and a strip-shaped cylinder with the diameter phi of 3mm is extruded under the pressure of 10 MPa. And (3) placing the extruded material at room temperature for 24h, baking the extruded material in a baking oven at 100 ℃ for 6h, and then transferring the extruded material into a muffle furnace at 650 ℃ for baking for 4h to obtain a cylindrical carrier with the diameter of 2.9-3 mm and the length of 4-6 mm.

(2) 35.1g of chromium nitrate, 10.5g of zirconium nitrate and 2g of nitric acid were weighed and dissolved in 50g of deionized water to obtain a dipping solution I. In addition, 17.55g of chromium nitrate and 2.15g of potassium nitrate were weighed and dissolved in 50g of deionized water to obtain immersion liquid II.

(3) And (3) dipping the dipping solution I in the step (2) into 100g of the roasted cylindrical carrier in the step (1), roasting in a 100 ℃ oven for 2h, and then transferring into a 550 ℃ muffle furnace for roasting for 2h to obtain a catalyst intermediate.

(4) And (3) dipping the catalyst intermediate in the step (3) by using the dipping solution II in the step (2), putting a dipping sample into a 100 ℃ oven for treatment for 4h, and then transferring into a 750 ℃ muffle furnace for roasting for 6h to obtain a catalyst sample 9. The TPR diagram is shown in FIG. 4.

The TPR test result from catalyst sample 9 is shown in FIG. 3, and no significant peak appears in the range of 380 to 580 ℃.

Evaluation of the properties of catalyst sample 9: the catalyst evaluation apparatus and evaluation conditions were the same as in example 1, and the catalyst evaluation results are shown in table 1.

TABLE 1

The specific embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A propane dehydrogenation catalyst comprising: alumina containing IVB group elements is used as a carrier, cr or an oxide thereof is used as an active component, and IA group and/or IIA group elements or an oxide thereof is used as an auxiliary component; wherein the catalyst has alloy peaks of IVB group elements and Cr element as active component in 380-580 deg.c, which is measured by TPR test.

2. The catalyst of claim 1, wherein the catalyst comprises, in parts by weight:

a) 10-30 parts of Cr element or its oxide;

c) 60-90 parts of a carrier;

3. The catalyst according to claim 1 or 2, wherein the group IVB element is selected from any one or two of Ti, zr;

and/or, the IA group element is selected from any one or more of Li, na, K and Cs, preferably Na and/or K;

and/or, the IIA element is selected from any one or two of Mg and Ca.

4. The catalyst according to claim 1, wherein the content of the auxiliary component in the catalyst is 0.1 to 3.0 parts, preferably 0.1 to 2.0 parts;

and/or, the carrier contains 0.5 to 3.0 parts of an element selected from group IVB or an oxide thereof.

5. The catalyst of claim 1, wherein the catalyst is prepared by loading a part of the active component Cr on an alumina carrier containing the element of group IVB, calcining, loading the rest of the active component Cr and an auxiliary component, and calcining, wherein the element of group IVB is introduced into the carrier by a mixing method.

6. A process for the preparation of a propane dehydrogenation catalyst as claimed in any of claims 1 to 5 comprising:

(1) Preparing an alumina carrier containing a group IVB element, wherein the group IVB element is introduced into the carrier by adopting a mixing method;

(2) Preparing a first Cr-containing compound and an acidic substance into an impregnation solution I, and preparing a second Cr-containing compound and an auxiliary agent-containing compound into an impregnation solution II;

7. The method according to claim 6, wherein the step (1) of preparing the carrier comprises: preparing an alumina precursor and a compound containing IVB group elements into a forming body, and drying and roasting to obtain an alumina carrier containing IVB group elements; the drying and roasting are carried out in an oxygen-containing atmosphere, and the drying conditions are as follows: the drying temperature is 80-180 ℃, and the drying time is 2-24 h; the roasting conditions are as follows: the roasting temperature is 500-900 ℃, and the roasting time is 2-12 h.

8. The method according to claim 6, wherein in the step (2), the first Cr-containing compound and the second Cr-containing compound are each independently selected from soluble compounds selected from at least one of nitrate, sulfate and chromate;

and/or in the step (2), the compound containing the element in the group IA is selected from at least one of nitrate, chloride or sulfate, and the compound containing the element in the group IIA is selected from at least one of nitrate and chloride.

9. The method according to claim 6, wherein in the step (2), the acidic substance is at least one selected from the group consisting of nitric acid, formic acid, acetic acid, adipic acid, oxalic acid and maleic acid; in the impregnation liquid I, the mass concentration of acidic substances is 1.5-10%, and the mass concentration of Cr is 7-30%;

and/or in the impregnation liquid II, the mass concentration of the auxiliary agent is 0.4-3.5% and the mass concentration of Cr is 5-20% calculated by elements;

and/or the mass ratio of the amount of Cr introduced into the catalyst by the impregnating solution I to the amount of Cr introduced into the catalyst by the impregnating solution II is 1-3: 1.

10. the production method according to claim 6, wherein the first drying and the first calcining in the step (3) are performed in an oxygen-containing atmosphere, and the first drying conditions are as follows: the drying temperature is 80-160 ℃, the drying time is 2-24 h, and the first roasting condition is as follows: the roasting temperature is 550-800 ℃, and the roasting time is 1-10 h;

and/or, the second drying and the second roasting in the step (4) are carried out in an oxygen-containing atmosphere, and the second drying conditions are as follows: the drying temperature is 80-150 ℃, the drying time is 1-16 h, and the second roasting condition is as follows: the roasting temperature is 600-800 ℃, and the roasting time is 2-15 h.

11. Use of the propane dehydrogenation catalyst of any of claims 1 to 5 in the dehydrogenation of propane to propylene.

12. Use according to claim 11, characterized in that the reaction conditions for the propane dehydrogenation are as follows: the reaction temperature is 550-620 ℃, the reaction pressure is 0.05-0.1 MPa, and the propane volume space velocity is 0.4-1.0 h ^-1 。