A chromium-modified indium oxide catalyst and its preparation method and application

Abstract

The present invention belongs to the field of new energy and new materials, and specifically relates to a chromium-modified indium oxide catalyst and its preparation method and application. The catalyst raw material includes commercial hydrated indium nitrate and hydrated chromium nitrate, and a highly dispersed chromium-modified indium oxide catalyst is prepared by a coprecipitation method, wherein the mass fraction of chromium in indium oxide is 0.5%-10%, and the obtained catalyst improves the oxygen vacancy content of the indium oxide-based catalyst, enhances the dissociation ability of the indium oxide-based catalyst to hydrogen, and improves the stability of the indium oxide-based catalyst. The catalyst is applied to the reaction of hydrogenation of carbon dioxide to methanol, and the catalytic activity is high, especially when the mass fraction of chromium in indium oxide in the prepared catalyst is 2%, the catalytic activity is the highest. The preparation process of the present invention is simple to operate, the raw materials are cheap and easy to obtain, and the potential of non-precious metal modified metal oxides in catalyst material design and application is expanded.

Description

Technical Field

[0001] The invention belongs to the field of new energy and new materials, and specifically relates to a chromium-modified indium oxide catalyst and a preparation method and application thereof. Background Art

[0002] Since the Industrial Revolution, while human production has improved, a large amount of heat-absorbing greenhouse gases, represented by carbon dioxide, have been emitted into the atmosphere, causing the global average temperature to rise, resulting in the greenhouse effect, and leading to a series of adverse effects such as land desertification and sea level rise, which have attracted widespread attention from all countries. The greenhouse effect has had a severe impact on agricultural production and the ecological environment in various countries. Hydrogen has been widely used as a new energy source in recent years. Its biggest advantage is that it produces water after the combustion reaction, which will not cause secondary pollution to the environment.

[0003] As an important industrial raw material, methanol is widely used to produce various industrial products such as acetic acid. With the advancement of science and technology, methanol has played an important role in various industries such as industry, agriculture, medicine, and biology. However, there are still problems such as low conversion rate and unsatisfactory yield in industrial methanol. Indium oxide has entered the public eye with its excellent methanol selectivity. It has a large number of oxygen vacancies, which provides a large number of active sites for the activation and conversion of carbon dioxide. However, indium oxide and catalysts still have problems such as low conversion rate and limited ability to dissociate hydrogen. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a chromium-modified indium oxide catalyst and a preparation method thereof. The catalyst reasonably utilizes non-metal modification and is expected to obtain high catalytic activity and reaction stability in the carbon dioxide hydrogenation reaction. The preparation process is simple and the raw materials are cheap and readily available. To achieve the above purpose, the present invention provides the following technical solutions:

[0005] A chromium-modified indium oxide catalyst, the raw materials include commercial hydrated indium nitrate and hydrated chromium nitrate, and a highly dispersed chromium-modified indium oxide catalyst is prepared by a coprecipitation method, wherein the mass fraction of chromium in the indium oxide is 0.5%-10%. As a further preferred embodiment, the mass fraction of chromium in the indium oxide is 2%.

[0006] The method for preparing the above-mentioned chromium-modified indium oxide catalyst comprises the following steps:

[0007] (1) Weigh commercial hydrated indium nitrate, hydrated chromium nitrate, and a precipitant according to a certain mass ratio; add the weighed hydrated indium nitrate and hydrated chromium nitrate into ultrapure water, stir magnetically for 30 minutes at room temperature, and fully dissolve to form solution A; dissolve 100 mg of the precipitant in ultrapure water, stir magnetically for 30 minutes at room temperature, and fully dissolve to form solution B, wherein the concentration of the precipitant is 25 g / L-300 g / L; after stirring, use a peristaltic pump to drip solution B into solution A at a certain rate, and then age for a certain time;

[0008] (2) filtering the reaction product obtained in step (1), washing the filtered solid with ultrapure water for 3-5 times, and then drying it at 60° C. for 6 h;

[0009] (3) placing the dried solid obtained in step (2) in a muffle furnace and calcining it at 300-500° C. for 3 h in an air atmosphere; placing the calcined solid in a tube furnace and calcining it at 250-500° C. for 2 h in 10 vol% H2 / Ar at a flow rate of 60 mL / min; and obtaining the final product.

[0010] Preferably, in step (1), the mass ratio of commercial hydrated indium nitrate to hydrated chromium nitrate is 1-35:1.

[0011] Preferably, in step (1), the temperature of the solution during titration and aging is 20°C-80°C.

[0012] Preferably, in step (1), the titration rate is 1 mL / min-5 mL / min.

[0013] Preferably, in step (1), the aging time is 1 h to 48 h.

[0014] Preferably, in step (1), the pH range of the solution after the titration is 7-11. As a further preference, the pH after the titration is 9.

[0015] Preferably, in step (1), the precipitant selected is any one of anhydrous sodium carbonate, aqueous ammonia, and sodium hydroxide.

[0016] Preferably, in step (3), the calcination temperature is 380°C.

[0017] As further preferred, the precipitant is anhydrous sodium carbonate, and the concentration of anhydrous sodium carbonate is 100 g / L.

[0018] The above-mentioned chromium-modified indium oxide catalyst is used in the carbon dioxide hydrogenation reaction.

[0019] The chromium-modified indium oxide catalyst of the present invention improves the oxygen vacancy content of the indium oxide-based catalyst, enhances the dissociation ability of the indium oxide-based catalyst to hydrogen, and improves the stability of the indium oxide-based catalyst. The catalyst is applied to the reaction of hydrogenating carbon dioxide to produce methanol, and has high catalytic activity, especially when the mass fraction of chromium in indium oxide in the prepared catalyst is 2%, the catalytic activity is the highest. The preparation process of the present invention is simple to operate, the raw materials are cheap and easy to obtain, and at the same time, the potential of non-precious metal modified metal oxides in catalyst material design and application is expanded. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The XRD spectrum of 2% Cr-In2O3 provided in Example 1;

[0021] Figure 2 A low magnification TEM image of 2% Cr-In2O3 provided in Example 1;

[0022] Figure 3 A is a high-magnification STEM image of the particle size distribution of 2% Cr-In2O3 provided in Example 1; B, C, and D are surface distribution images of In, Cr, and O elements in the EDX element distribution image results of 2% Cr-In2O3 provided in Example 1;

[0023] Figure 4 H2-TPR diagram of 2% Cr-In2O3 provided in Example 1;

[0024] Figure 5 O of Cr-In2O3 (In2O3) provided in Examples 1-5 1s XPS images;

[0025] Figure 6 The carbon dioxide conversion rate of the carbon dioxide hydrogenation to methanol of Cr-In2O3 (In2O3) provided in Examples 1-5;

[0026] Figure 7 The selectivity of methanol in the carbon dioxide hydrogenation reaction of Cr-In2O3 (In2O3) provided in Examples 1-5. DETAILED DESCRIPTION

[0027] The accompanying drawings are only for illustrative purposes; in order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the present invention in any way. Unless otherwise specified, the methods, reagents and equipment used in the present invention are conventional methods, reagents and equipment in the art, and the reagents and equipment can be obtained from commercial sources.

[0028] Example 1

[0029] A chromium-modified indium oxide catalyst is prepared by a coprecipitation method to obtain a highly dispersed chromium-modified indium oxide catalyst, wherein the mass fraction of chromium in the indium oxide is 2%.

[0030] The preparation method of the above-mentioned chromium-modified indium oxide catalyst specifically comprises:

[0031] 1.15 g of hydrated indium nitrate and 0.31 g of hydrated chromium nitrate were weighed and dissolved in ultrapure water, and magnetically stirred at room temperature for 30 min to form solution A, in which the mass fraction of chromium in indium oxide was 2%; 100 mg of anhydrous sodium carbonate and a certain amount of ultrapure water were magnetically stirred at room temperature for 30 min to form solution B; after stirring, a peristaltic pump was used to drip solution B into solution A at a certain rate until pH = 9, and aged for 3 h;

[0032] The reaction product was filtered, washed with ultrapure water five times, and the solid was dried at 60 °C for 6 h;

[0033] The obtained dried solid was placed in a muffle furnace and calcined at 450°C for 3 h in an air atmosphere; the calcined solid was placed in a tube furnace and calcined at 380°C for 2 h in 10 vol% H2 / Ar at a flow rate of 60 mL / min; the final product 2% Cr-In2O3 catalyst was obtained.

[0034] The XRD spectrum of 2% Cr-In2O3 provided in this embodiment is shown in the attached figure. Figure 1 As shown, the low magnification TEM spectrum is as attached Figure 2 As shown, high magnification TEM images are shown in the attached Figure 3 A, the element analysis diagram is shown in the attached Figure 3 As shown in B, C, and D in the figure, H2-TPR is shown in the attached figure. Figure 4 shown.

[0035] In the attached Figure 1 In the chromatogram, all the crystal phases belonging to cubic indium oxide can be observed, and no diffraction peak of Cr appears, indicating the high dispersion of Cr. Figure 2 With attached Figure 3 Figure A shows that the synthesized Cr-In2O3 sample presents a cubic dispersed nanoparticle morphology. Figure 3 B, C, and D show the high dispersion of the components of the nanoparticles. Figure 4 The reduction peaks at 200°C-300°C are attributed to the partial reduction of chromium oxide, and those after 400°C are all reduction peaks of indium oxide.

[0036] Example 2

[0037] A chromium-modified indium oxide catalyst is prepared by a coprecipitation method to obtain a highly dispersed chromium-modified indium oxide catalyst, wherein the mass fraction of chromium in the indium oxide is 1%.

[0038] The preparation method of the above-mentioned chromium-modified indium oxide catalyst specifically comprises:

[0039] 1.15 g of hydrated indium nitrate and 0.16 g of hydrated chromium nitrate were weighed and dissolved in ultrapure water, and magnetically stirred at room temperature for 30 min to form solution A, in which the mass fraction of chromium in indium oxide was 1%; 100 mg of anhydrous sodium carbonate and a certain amount of ultrapure water were magnetically stirred at room temperature for 30 min to form solution B; after stirring, a peristaltic pump was used to drip solution B into solution A at a certain rate until pH = 9, and aged for 3 h;

[0040] The reaction product was filtered, washed with ultrapure water five times, and the solid was dried at 60 °C for 6 h;

[0041] The obtained dried solid was placed in a muffle furnace and calcined at 450°C for 3 h in an air atmosphere; the calcined solid was placed in a tube furnace and calcined at 380°C in 10 vol% H2 / Ar with a flow rate of 60 mL / min for 2 h; the final product was a 1% Cr-In2O3 catalyst.

[0042] Example 3

[0043] A chromium-modified indium oxide catalyst is prepared by a coprecipitation method to obtain a highly dispersed chromium-modified indium oxide catalyst, wherein the mass fraction of chromium in the indium oxide is 3%.

[0044] The preparation method of the above-mentioned chromium-modified indium oxide catalyst specifically comprises:

[0045] 1.15 g of hydrated indium nitrate and 0.48 g of hydrated chromium nitrate were weighed and dissolved in ultrapure water, and magnetically stirred at room temperature for 30 min to form solution A, in which the mass fraction of chromium in indium oxide was 3%; 100 mg of anhydrous sodium carbonate and a certain amount of ultrapure water were magnetically stirred at room temperature for 30 min to form solution B; after stirring, a peristaltic pump was used to drip solution B into solution A at a certain rate until pH = 9, and aged for 3 h;

[0046] The reaction product was filtered, washed with ultrapure water five times, and the solid was dried at 60 °C for 6 h;

[0047] The obtained dried solid was placed in a muffle furnace and calcined at 450°C for 3 h in an air atmosphere; the calcined solid was placed in a tube furnace and calcined at 380°C for 2 h in 10 vol% H2 / Ar at a flow rate of 60 mL / min; the final product 3% Cr-In2O3 catalyst was obtained.

[0048] Example 4

[0049] A chromium-modified indium oxide catalyst is prepared by a coprecipitation method to obtain a highly dispersed chromium-modified indium oxide catalyst, wherein the mass fraction of chromium in the indium oxide is 5%.

[0050] The preparation method of the above-mentioned chromium-modified indium oxide catalyst specifically comprises:

[0051] 1.15 g of hydrated indium nitrate and 0.80 g of hydrated chromium nitrate were weighed and dissolved in ultrapure water, and magnetically stirred at room temperature for 30 min to form solution A, in which the mass fraction of chromium in indium oxide was 5%; 100 mg of anhydrous sodium carbonate and a certain amount of ultrapure water were magnetically stirred at room temperature for 30 min to form solution B; after stirring, a peristaltic pump was used to drip solution B into solution A at a certain rate until pH = 9, and aged for 3 h;

[0052] The reaction product was filtered, washed with ultrapure water five times, and the solid was dried at 60 °C for 6 h;

[0053] The obtained dried solid was placed in a muffle furnace and calcined at 450°C for 3 h in an air atmosphere; the calcined solid was placed in a tube furnace and calcined at 380°C for 2 h in 10 vol% H2 / Ar at a flow rate of 60 mL / min; and the final product 5% Cr-In2O3 catalyst was obtained.

[0054] Example 5

[0055] 1.15 g of hydrated indium nitrate was weighed and dissolved in ultrapure water, and magnetically stirred at room temperature for 30 min to form solution A; 100 mg of anhydrous sodium carbonate and a certain amount of ultrapure water were magnetically stirred at room temperature for 30 min to form solution B; after stirring, a peristaltic pump was used to drip solution B into solution A at a certain rate until pH = 9, and aged for 3 h;

[0056] The reaction product was filtered, washed with ultrapure water five times, and the solid was dried at 60 °C for 6 h;

[0057] The obtained dried solid was placed in a muffle furnace and calcined at 450°C for 3 hours in an air atmosphere; the calcined solid was then placed in a tubular furnace and calcined in 10 vol% H2 / Ar at a temperature of 380°C and a flow rate of 60 mL / min for 2 hours to obtain the final product In2O3 catalyst.

[0058] like Figure 5 Shown is the product obtained in Example 1-5 1s XPS images. It can be observed from the figure that with the incorporation of Cr, the surface oxygen vacancy content gradually increases.

[0059] Proof Experiment

[0060] The carbon dioxide hydrogenation activity test was performed on the Cr-In2O3 prepared in Examples 1-5, and the specific steps are as follows:

[0061] Accurately weigh 600 mg of the catalyst prepared in Examples 1-5 (20-40 mesh) and load it into the reaction tube. Pass Ar (99.999%) to purify for 30 min; pass H2 (99.999%) to reduce in situ for 2 h (380°C), pass raw gas to carry out carbon dioxide hydrogenation reaction (H2:CO2=3:1, Ar balance) (reaction conditions: 5Mpa, 3000mL / gcat·h, 200°C-300°C), and use TCD and FID detectors to detect the reaction products (Agilent 8890).

[0062] The carbon dioxide conversion rate is shown in the attached Figure 6 The methanol selectivity is shown in the attached Figure 7 The specific values ​​are shown in Table 1, which is a comparison of the carbon dioxide hydrogenation performance of the catalysts.

[0063] Table 1: Comparison of catalyst performance for carbon dioxide hydrogenation

[0064]

[0065] From the attached Figure 6 , 7 As can be seen from Table 1, with the increase of doping amount, the selectivity of methanol and the conversion rate of CO2 both show a volcano-shaped curve. When 2% Cr-In2O3 is used as a catalyst, the methanol selectivity reaches 92.82% (250°C) and the conversion rate of CO2 reaches 9.37% (250°C), which is the best chromium-modified indium oxide catalyst prepared, that is, when the mass fraction of chromium in indium oxide is 2%, the obtained catalyst has the best catalytic performance in the carbon dioxide hydrogenation reaction.

[0066] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a chromium-modified indium oxide catalyst, characterized in that: The raw materials include commercial hydrated indium nitrate and hydrated chromium nitrate, and a highly dispersed chromium-modified indium oxide catalyst is prepared by a co-precipitation method, wherein the mass fraction of chromium in the indium oxide is 2%; The preparation method comprises the following steps: (1) Weigh 1.15 g of hydrated indium nitrate and 0.31 g of hydrated chromium nitrate, add the weighed hydrated indium nitrate and hydrated chromium nitrate into ultrapure water, stir magnetically for 30 min at room temperature, and fully dissolve to form solution A; dissolve 100 mg of anhydrous sodium carbonate in ultrapure water, stir magnetically for 30 min at room temperature to form solution B, the concentration of the precipitant is 25 g / L-300 g / L; after stirring, use a peristaltic pump to drip solution B into solution A at a certain rate, the titration rate is 1 mL / min, after the titration, the solution pH is 9, and then age for 3 h; (2) filtering the reaction product obtained in step (1), washing the filtered solid with ultrapure water for 3-5 times, and then drying it at 60° C. for 6 h; (3) The dried solid obtained in step (2) was placed in a muffle furnace and calcined at 450°C for 3 h in an air atmosphere; the calcined solid was placed in a tube furnace and calcined at 380°C in 10 vol% H2 / Ar at a flow rate of 60 mL / min for 2 h to obtain the final product.

2. The method for preparing a chromium-modified indium oxide catalyst according to claim 1, characterized in that: In the step (1), the temperature of the solution during titration and aging is 20°C-80°C.

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