Nickel-vanadium oxide catalyst, preparation method thereof and method for preparing propylene by catalyzing oxidative dehydrogenation of propane

Abstract

The invention discloses a nickel-vanadium oxide catalyst, a preparation method thereof and a method for preparing propylene by catalyzing oxidative dehydrogenation of propane. The invention aims to provide the preparation method of the nickel-vanadium oxide catalyst, and the nickel-vanadium oxide catalyst has relatively high selectivity for catalyzing oxidative dehydrogenation of propane to prepare propylene under a low-temperature condition. The technical scheme is as follows: (1) preparing a vanadium trichloride aqueous solution; (2) adding nickel chloride hexahydrate and urea into the vanadium trichloride aqueous solution, and stirring for 1 hour at normal temperature; (3) putting the obtained solution into a reaction kettle for hydrothermal reaction; (4) centrifuging, washing with deionized water, and drying in vacuum to obtain a solid product; and (5) calcining the solid product at 600 DEG C for 4 hours to obtain a finished product. Belongs to the technical field of thermocatalytic materials and environmental protection.

Description

Technical Field

[0001] The invention relates to a catalyst, in particular to a nickel-vanadium oxide catalyst. The invention also relates to a method for preparing the nickel-vanadium oxide catalyst, and belongs to the technical field of thermal catalytic materials and environmental protection. Background Art

[0002] Propylene is a key raw material for three important synthetic materials: plastics, rubber and chemical fibers. The market demand for propylene derivatives is growing rapidly. Currently, propylene is mainly produced by steam cracking and fluid catalytic cracking processes of petroleum by-products (such as naphtha and light diesel) and the dehydrogenation of propane. With the decline in the cost of alkane extraction in shale gas, oxidative dehydrogenation of propane (ODHP) has attracted increasing attention due to its advantages such as low energy consumption, low carbon deposition and thermodynamic permissibility. However, how to inhibit deep oxidation and improve catalyst activity and olefin selectivity remains a key issue in the industrialization of ODHP.

[0003] Transition metal oxides include V-based, Cr-based, Ni-based, Mo-based, rare earth-based, etc., which are the main components of ODHP catalysts. Although molybdenum-based and vanadium-based catalysts have high propylene selectivity, they have high requirements for reaction temperature (T > 500℃). Supported vanadium oxide-based catalysts are the most studied in ODHP, but the acid-base properties of the carrier must be controlled, and a basic carrier that is conducive to propylene desorption can be selected to obtain a catalyst with good catalytic performance. In recent years, nickel oxide catalysts have been favored by researchers for their ability to activate alkanes at low temperatures. Compared with other catalyst systems, nickel-based catalysts have the characteristics of low temperature, high activity and low cost, and are considered to be a catalyst system with industrial potential. Therefore, nickel is doped in vanadium oxide catalysts to make nickel vanadium oxide catalysts to achieve low-temperature catalytic propane oxidative dehydrogenation to propylene. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a method for preparing a nickel vanadium oxide catalyst based on the problems currently faced by transition metal-based catalysts and to have high selectivity for the oxidative dehydrogenation of propane to propylene under low temperature conditions.

[0005] In order to achieve the above object, the first technical solution provided by the present invention is as follows: A method for preparing a nickel-vanadium oxide catalyst comprises the following steps in sequence: (1) preparing a vanadium trichloride aqueous solution using sodium metavanadate, hydrochloric acid, oxalic acid and sodium dithionite; (2) adding nickel chloride hexahydrate and urea to the vanadium trichloride aqueous solution, and stirring the solution for 1 hour; (3) placing the obtained solution into a reaction kettle for hydrothermal reaction; (4) centrifuging, washing with deionized water, and vacuum drying to obtain a solid product; (5) calcining the solid product in an air atmosphere to obtain a finished product; belonging to the field of thermal catalytic materials and environmental protection technology.

[0006] Furthermore, in the preparation method of the nickel vanadium oxide catalyst, the vanadium trichloride aqueous solution described in step (1) is obtained by adding 0.25 mL of hydrochloric acid to 2.5 mmol of sodium metavanadate aqueous solution, adjusting the pH value to 2 with oxalic acid, and adjusting the pH value to 5 with sodium dithionite.

[0007] Furthermore, in the preparation method of the nickel vanadium oxide catalyst, the stirring speed in step (2) is 500 r / min.

[0008] Furthermore, in the preparation method of the nickel-vanadium oxide catalyst, the hydrothermal temperature in step (3) is 140° C. and the temperature is kept for 14 h.

[0009] Furthermore, in the preparation method of the above nickel vanadium oxide catalyst, the centrifugal parameters in step (4) are: 8000 r / min, time 5 min; the washing conditions are: deionized water and ethanol washing 3 times each; the drying temperature is 60°C, and the time is 12 h.

[0010] Furthermore, in the preparation method of the nickel-vanadium oxide catalyst, the calcination temperature in step (5) is 600° C. and the calcination time is 4 hours.

[0011] The second technical solution provided by the present invention is a nickel-vanadium oxide catalyst prepared by the above method.

[0012] The catalyst is used to catalyze the method of oxidative dehydrogenation of propane to prepare propylene. The catalytic conditions are: the raw gas composition is: 5% propane, 4% oxygen, the balance gas is nitrogen, the space velocity is 5200mL / (g·h), and the reaction temperature is 180-200℃.

[0013] The NiVO provided by the present invention x The catalyst is used in the field of thermal catalysis.

[0014] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages: (1) Only transition metals are used in the preparation process, which greatly reduces the cost price; (2) NiVO x Highly dispersed active sites are obtained through high-temperature calcination treatment, thereby improving its ability to adsorb oxygen and improve its ability to oxidatively dehydrogenate propane; (3) The catalyst preparation cost is low, the preparation conditions are simple, the operation is convenient, and it is easy to scale up production in industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 NiVO x Schematic diagram of catalyst synthesis; Figure 2 For example 1 NiVO x Scanning electron microscopy (SEM). DETAILED DESCRIPTION

[0016] The technical solution of the present invention will be described in detail below through specific embodiments, but it should be clearly stated that these embodiments are for illustration and are not to be construed as limiting the scope of the present invention.

[0017] Example 1: This example provides a NiVO for thermal catalytic propane oxidative dehydrogenation to propylene x A method for preparing a catalyst, which is prepared by the following method: (1) 0.3048 g of NaVO3 was added to 20 mL of deionized water, 0.25 mL of concentrated HCl was added, oxalic acid was added to adjust the pH value to 2, and sodium dithionite was added to adjust the pH value to 5 to obtain a vanadium trichloride aqueous solution; (2) 2.3769 g NiCl2·6H2O and 1.8618 g urea were added to the vanadium trichloride aqueous solution, and the solution was stirred on a magnetic stirrer at 500 r / min for 1 hour; (3) placing the obtained solution into a reactor for hydrothermal reaction at 140° C. for 14 hours and then cooling naturally to room temperature; (4) Centrifugation, washing with deionized water and ethanol, and vacuum drying to obtain a solid product. The centrifugation parameters are: 8000 r / min, time 5 min; washing conditions are: washing with deionized water and ethanol 3 times each; drying temperature is 60°C, time is 12 h. ; (5) The solid product is calcined in air atmosphere to obtain a finished product at a calcination temperature of 600°C and a calcination time of 4 hours. The obtained sample is represented by Ni4VO x .

[0018] Example 2: This example provides a NiVO for thermal catalytic propane oxidative dehydrogenation to propylene x A method for preparing a catalyst, which is prepared by the following method: (1) 3.6579 g of NaVO3 was added to 20 mL of deionized water, 0.25 mL of concentrated HCl was added, oxalic acid was added to adjust the pH value to 2, and sodium dithionite was added to adjust the pH value to 5 to obtain a vanadium trichloride aqueous solution; (2) 1.4261 g NiCl2·6H2O and 3.78 g urea were added to the vanadium trichloride aqueous solution, and the solution was stirred on a magnetic stirrer at 500 r / min for 1 hour; (3) placing the obtained solution into a reactor for hydrothermal reaction at 140° C. for 14 hours and then cooling naturally to room temperature; (4) Centrifugation, washing with deionized water and ethanol, and vacuum drying to obtain a solid product. The centrifugation parameters are: 8000 r / min, time 5 min; washing conditions are: washing with deionized water and ethanol 3 times each; drying temperature is 60°C, time is 12 h. ; (5) The solid product is calcined in air atmosphere to obtain a finished product at a calcination temperature of 600°C and a calcination time of 4 hours. The obtained sample is represented by NiV4O x .

[0019] Example 3: This example provides a NiVO for thermal catalytic propane oxidative dehydrogenation to propylene x A method for preparing a catalyst, which is prepared by the following method: (1) 0.3048 g of NaVO3 was added to 20 mL of deionized water, 0.25 mL of concentrated HCl was added, oxalic acid was added to adjust the pH value to 2, and sodium dithionite was added to adjust the pH value to 5 to obtain a vanadium trichloride aqueous solution; (2) 1.8618 g of urea was added to the vanadium trichloride aqueous solution, and the solution was stirred on a magnetic stirrer at 500 r / min for 1 hour; (3) placing the obtained solution into a reactor for hydrothermal reaction at 140° C. for 14 hours and then cooling naturally to room temperature; (4) Centrifugation, washing with deionized water and ethanol, and vacuum drying to obtain a solid product. The centrifugation parameters are: 8000 r / min, time 5 min; washing conditions are: washing with deionized water and ethanol 3 times each; drying temperature is 60°C, time is 12 h. ; (5) The solid product is calcined in air atmosphere to obtain a finished product at a calcination temperature of 600°C and a calcination time of 4 hours. The obtained sample is denoted as VO x .

[0020] Example 4: This example provides a NiVO for thermal catalytic propane oxidative dehydrogenation to propylene x A method for preparing a catalyst, which is prepared by the following method: (1) 2.3769 g NiCl2·6H2O and 1.8618 g urea were added to a vanadium trichloride aqueous solution, and the solution was stirred on a magnetic stirrer at 500 r / min for 1 hour; (2) placing the obtained solution into a reactor for hydrothermal reaction at 140° C. for 14 hours and then cooling naturally to room temperature; (3) Centrifugation, washing with deionized water and ethanol, and vacuum drying to obtain a solid product. The centrifugation parameters are: 8000 r / min, time 5 min; washing conditions are: washing with deionized water and ethanol 3 times each; drying temperature is 60°C, time is 12 h. ; (4) The solid product is calcined in air atmosphere to obtain a finished product at a calcination temperature of 600°C and a calcination time of 4 hours. The obtained sample is represented by NiO x .

[0021] Table 1 NiVO x Catalyst activity evaluation results Examples 1-4 Preparation of NiVO by hydrothermal + calcination method x , wherein Example 2 compares the effects of different nickel-vanadium ratios, and Examples 3 and 4 serve as comparative samples to compare the performance of separation of the active component and the carrier.

[0022]

[0023] It can be seen from the table that the conversion rate and selectivity of the catalysts of Examples 2-4 for catalyzing propane oxidative dehydrogenation at 180°C under the same conditions are not as high as those of Example 1; this indicates that there is an interaction between the metal active component and the carrier and this interaction will only work when the nickel-vanadium ratio is 4:1. Therefore, Example 1 provides a thermal catalyst with excellent activity.

[0024] The above are only preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for preparing a nickel-vanadium oxide catalyst, characterized in that: The following steps are included in sequence: (1) preparing a vanadium trichloride aqueous solution using sodium metavanadate, hydrochloric acid, oxalic acid and sodium dithionite; (2) Add nickel chloride hexahydrate and urea to the vanadium trichloride aqueous solution and stir for 1 hour at room temperature; (3) placing the obtained solution into a reaction kettle for hydrothermal reaction; (4) centrifuging, washing with deionized water, and vacuum drying to obtain a solid product; (5) calcining the solid product under air atmosphere to obtain a finished product; The invention belongs to the technical field of thermal catalytic materials and environmental protection.

2. The method for preparing the nickel-vanadium oxide catalyst according to claim 1, characterized in that: The vanadium trichloride aqueous solution described in step (1) is obtained by adding 0.25 mL of hydrochloric acid to 2.5 mmol of sodium metavanadate aqueous solution, adjusting the pH value to 2 with oxalic acid, and adjusting the pH value to 5 with sodium dithionite.

3. The method for preparing the nickel-vanadium oxide catalyst according to claim 1, characterized in that: The stirring speed described in step (2) is 500r / min.

4. The method for preparing the nickel-vanadium oxide catalyst according to claim 1, characterized in that: The hydrothermal temperature in step (3) is 140° C. and the temperature is kept for 14 h.

5. The method for preparing the nickel-vanadium oxide catalyst according to claim 1, characterized in that: The centrifugal parameters in step (4) are: 8000 r / min, time 5 min; the washing conditions are: deionized water and ethanol washing 3 times each; the drying temperature is 60°C, and the time is 12 h.

6. The method for preparing the nickel-vanadium oxide catalyst according to claim 1, characterized in that: In step (5), the calcination temperature is 600° C. and the calcination time is 4 h.

7. A nickel-vanadium oxide catalyst, characterized in that The method is prepared by any one of claims 1 to 6.

8. A method for preparing propylene by oxidative dehydrogenation of propane using the nickel-vanadium oxide catalyst according to claim 7, characterized in that: The catalytic conditions are as follows: the raw gas composition is: 5% propane, 4% oxygen, the balance gas is nitrogen, the space velocity is 5200 mL / (g·h), and the reaction temperature is 180-200°C.

9. The nickel-vanadium oxide catalyst provided by the present invention is applied in the field of thermal catalysis. The catalyst has a certain catalytic efficiency for monomeric small molecule organic matter and can be used to degrade common organic pollutants in the air.

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