A nickel / lanthanum oxide catalyst, its preparation method and application

Abstract

The application discloses a nickel / lanthanum oxide catalyst and a preparation method and application thereof. The preparation method comprises the following steps: performing a parallel flow co-precipitation reaction on a mixed reaction system containing a precipitant, a nickel salt, a lanthanum salt and a solvent to obtain a catalyst precursor; and performing a calcination treatment on the catalyst precursor to obtain the nickel / lanthanum oxide catalyst. The preparation of the catalyst is performed in a relatively narrow pH value range (7.5-8.5), and the simultaneous precipitation of Ni and La is performed, so that the highly uniform dispersion of Ni in the carrier is ensured; the preparation steps are simple; the preparation process is green and energy-saving; the obtained nickel / lanthanum oxide catalyst has relatively high activity and catalytic efficiency; when the catalyst is used in a dry reforming reaction of methane and carbon dioxide, the generation of carbon deposition is obviously inhibited, and the conversion rates of methane and carbon dioxide are both very high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of heterogeneous catalysis, and relates to a nickel / lanthanum oxide catalyst as well as a preparation method and application thereof, in particular to a nickel / lanthanum oxide catalyst as well as a preparation method thereof, and an application of the catalyst in a dry reforming reaction of methane and carbon dioxide. BACKGROUND

[0002] Synthesis gas composed of hydrogen and carbon monoxide is a raw material for Fischer-Tropsch synthesis of liquid hydrocarbon fuels, and is widely used in the production of olefins, methanol and dimethyl ether, etc., and can also be used as a basic raw material for the synthesis of oxygen-containing and nitrogen-containing chemicals by carbonylation and hydroformylation reactions, and is used more and more. The sources of synthesis gas in industry mainly include two channels, coal and natural gas, and the latter is obtained by a steam reforming reaction (SRM) of methane. In order to better utilize natural gas as a clean energy source and reduce the energy consumption of the process, for a long time, partial oxidation of methane (POM), dry reforming of methane and carbon dioxide (DRM) and autothermal reforming of methane (ATM) for synthesis gas have been intensively studied. Among them, the DRM process, in which both reactants are greenhouse gases and are also abundant and inexpensive carbon resources in nature, has attracted much attention.

[0003] The catalysts used in the dry reforming reaction of methane and carbon dioxide include noble metal catalysts (Ru, Rh, Pt, Pd, etc.) and non-noble metal catalysts (Ni, Co, Cu, etc.); although the noble metal catalysts have the advantages of high activity and good stability, they are scarce in resources and high in price, and are difficult to be used in large quantities in industry. Among the non-noble metal catalysts, the catalysts with Ni as the active component are favored because they have relatively high initial activity and relatively low price, but the problem of sintering of the Ni active component at high temperature and the decrease in activity caused by carbon deposition on the catalyst become the bottleneck for the industrial application of the catalyst.

[0004] To solve these problems, various means and strategies are taken, which can be summarized as follows: 1) inhibiting the aggregation of Ni during the reaction process; 2) improving the catalyst carrier or adjuvant, inhibiting carbon deposition by adjusting the acidity and basicity, or improving the dispersion of Ni and the carbon capacity by adjusting the pore structure. For example, the pore channel confinement effect is used to stabilize the size of Ni (Significant roles of mesostructure and basic modifier for ordered mesoporous Ni / CaO-Al2O3 catalyst towards CO2 reforming of CH4, Catalysis Science & Technology, 2014, 4, 1759-1770); a single-atom catalyst is formed by using metal-support strong interaction (Atomically dispersed nickel as coke-resistant active sites for methane dry reforming, Nature Communications 2019, 10(1), 5181), etc.

[0005] Compared with other basic carriers, the La2O3 supported Ni catalyst shows better stability because La2O3 can form La2O2CO3 with CO2 during the reaction. Verykios et al. have conducted a detailed study on the catalytic methane carbon dioxide reforming reaction over La2O3 supported Ni catalyst (Carbon dioxide reforming of methane to synthesis gas over Ni / La2O3 catalysts, Applied Catalysis A: General, 1996, 138, 109-133; Kinetic study of the catalytic reforming of methane with carbon dioxide to synthesis gas over Ni / La2O3 catalyst. Catalysis Today, 2001, 64, 83-90). In the existing published literature, the Ni / La2O3 catalyst is usually prepared by impregnation or precipitation method, for example, Chinese invention patent 201811589656.6 discloses a nickel supported mesoporous lanthanum oxide catalyst and its preparation method, which impregnates lanthanum oxide carrier with nickel salt; Muller et al. (Dry-reforming of methane over bimetallic Ni-M / La2O3 (M=Co, Fe): The effect of the rate of La2O2CO3 formation and phase stability on the catalytic activity and stability, Journal of Catalysis, 2016, 343, 208-214) prepared a bimetallic nickel / lanthanum oxide catalyst using sodium carbonate co-precipitation method. However, for lanthanum oxide carriers with relatively low specific surface area, impregnation method is not easy to obtain uniformly dispersed Ni particles. When preparing catalyst by precipitation method, active component with uniform distribution and appropriate interaction with the carrier can be obtained, but generally sodium ion containing precipitants are selected, in order to eliminate the influence of residual sodium, the catalyst needs to be washed strictly during preparation, which increases the complexity and energy consumption of the process. SUMMARY

[0006] The main purpose of the present application is to provide a nickel / lanthanum oxide catalyst and its preparation method and application to overcome the shortcomings of the prior art.

[0007] To achieve the above-mentioned purposes, the technical solutions adopted by the present application include:

[0008] The embodiment of the present application provides a preparation method of a nickel / lanthana catalyst, which comprises the following steps:

[0009] A mixed reaction system comprising a precipitant, a nickel salt, a lanthanum salt and a solvent is subjected to a parallel flow co-precipitation reaction to obtain a catalyst precursor, wherein the pH value of the mixed reaction system is 7.5-8.5;

[0010] The catalyst precursor is subjected to a calcination treatment to obtain the nickel / lanthana catalyst.

[0011] The embodiment of the present application further provides the nickel / lanthana catalyst prepared by the above method, wherein the phase of the nickel / lanthana catalyst comprises monoclinic La2O2CO3, hexagonal La2O2CO3, La2O3 and La2NiO4, and the content of nickel element in the nickel / lanthana catalyst is 0.1-5.0 wt%.

[0012] The embodiment of the present application further provides the use of the above nickel / lanthana catalyst in a dry reforming reaction of methane and carbon dioxide.

[0013] The embodiment of the present application further provides a dry reforming reaction method of methane and carbon dioxide, which comprises the following steps:

[0014] The nickel / lanthana catalyst is prepared by the above method;

[0015] The nickel / lanthana catalyst is subjected to a reduction treatment at 600-800 DEG C for 1-3 h in a reducing atmosphere;

[0016] Methane and carbon dioxide are continuously input into a tubular reactor provided with the nickel / lanthana catalyst subjected to the reduction treatment, and a reaction is carried out under the conditions that the temperature is 600-800 DEG C, the space velocity is 10000-50000 h-1, and the nickel / lanthana catalyst is generated. -1

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] (1) The present application uses ammonium carbonate and / or ammonium bicarbonate as the precipitant, and controls the pH value in the precipitation process in a small fluctuation range (pH value is 7.5-8.5), thereby improving the uniform dispersion of nickel on the carrier and enhancing the interaction between the two, so that the stability of the nickel / lanthana catalyst at high temperature is improved;

[0019] (2) The nickel / lanthana catalyst prepared by the present application has the lanthanum in the form of La2O2CO3 and La2O3 crystal phase and the nickel in the form of La2NiO4, so that the carbon dioxide activation and the sintering resistance of the active component of the catalyst at high temperature are improved;

[0020] ​(3) The present application prepares the nickel / lanthana catalyst, and harmful gases such as nitrogen oxides are not produced in the calcination process of the catalyst precursor because the nitrate or chloride is washed, which meets the development trend of green chemistry;

[0021] (4) The preparation method of the present application is simple, and the prepared catalyst has the characteristics of high activity component dispersion and good stability, which can effectively solve the problems of high carbon deposition rate and poor stability in the existing technology in the methane carbon dioxide reforming reaction;

[0022] (5) The nickel / lanthana catalyst prepared by the present application has high catalytic activity, and when the nickel loading is as low as 1wt%, the methane and carbon dioxide conversion rates are 85% and 92% respectively at 750℃, and the conversion rates are 862 and 964mmol·g -1 ·min -1 . BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0024] Figure 1 XRD patterns of the nickel / lanthana catalysts prepared in Examples 1-4 of the present application;

[0025] Figure 2 XRD patterns of the nickel / lanthana catalysts prepared in Comparative Examples 1-3 of the present application;

[0026] Figure 3 H2-TPR patterns of the NL-1 catalyst prepared in Example 1 of the present application and the C-1 catalyst prepared in Comparative Example 1;

[0027] Figures 4a-4b The results of the performance of the NL-1 catalyst in Example 1 and the C-1 catalyst in Comparative Example 1 in the methane / carbon dioxide dry reforming reaction with the change of reaction time are shown in the following two figures respectively;

[0028] Figure 5 TGA / DSC curves of the NL-1 catalyst in Example 1 and the C-1 catalyst in Comparative Example 1 after 100h of catalyzing the methane / carbon dioxide dry reforming reaction;

[0029] Figures 6a-6bTEM images of NL-1 catalyst in Example 1 and C-1 catalyst in Comparative Example 1 of the present application after 100 h of catalyzing dry reforming of methane and carbon dioxide. DETAILED DESCRIPTION

[0030] In view of the defects of the prior art, the present inventors have long studied and practiced and have finally proposed the technical solutions of the present application. The technical solutions of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0031] One aspect of the embodiments of the present application provides a preparation method of a nickel / lanthana catalyst, which comprises:

[0032] subjecting a mixed reaction system comprising a precipitant, a nickel salt, a lanthanum salt and a solvent to a parallel flow co-precipitation reaction to obtain a catalyst precursor;

[0033] and subjecting the catalyst precursor to a calcination treatment to obtain the nickel / lanthana catalyst, wherein the pH value of the mixed reaction system is 7.5-8.5.

[0034] In the present application, the nickel / lanthana catalyst is used for dry reforming of methane and carbon dioxide.

[0035] In some more specific embodiments, the preparation method specifically comprises:

[0036] dissolving the nickel salt and the lanthanum salt in water to form a first mixed solution;

[0037] dissolving the precipitant in water to form a precipitant solution;

[0038] and simultaneously adding the first mixed solution and the precipitant solution into the solvent at 20-50°C to form the mixed reaction system and control the pH value of the mixed reaction system to be 7.5-8.5, and then stirring the reaction at 20-50°C for 10-30 min, and then standing for 10-30 min to obtain the catalyst precursor.

[0039] Further, the nickel salt comprises any one or a combination of two or more of nickel chloride, nickel nitrate, nickel acetate and nickel sulfate, and is not limited thereto.

[0040] Further, the lanthanum salt comprises any one or a combination of two of lanthanum chloride and lanthanum nitrate, and is not limited thereto.

[0041] Further, the precipitant comprises any one or a combination of two of ammonium carbonate and ammonium bicarbonate, and is not limited thereto.

[0042] Further, the solvent includes water and / or an ethanol aqueous solution, and is not limited thereto.

[0043] Further, the concentration of the ethanol aqueous solution is less than 20wt%.

[0044] Further, the molar ratio of the nickel salt to the lanthanum salt in the first mixed solution is 0.02-0.5:1.

[0045] Further, the concentration of the precipitant in the precipitant solution is 0.1-2.0 mol / L.

[0046] Further, the volume ratio of the solvent to the sum of the first mixed solution and the precipitant solution is 1:1-1:2.

[0047] In some more specific embodiments, the temperature of the calcination treatment is 600-800°C, and the time is 2-4h.

[0048] In some more specific embodiments, the preparation method further includes: after the completion of the parallel flow co-precipitation reaction, filtering, washing, and drying the obtained mixture.

[0049] Further, the temperature of the drying treatment is 80-120°C, and the time is 8-12h.

[0050] In some more specific embodiments, the preparation method (parallel flow co-precipitation method) of the nickel / lanthanum oxide catalyst specifically includes:

[0051] (1) dissolving a nickel salt and a lanthanum salt in deionized water to form a solution A, the concentrations of the two salts being 0.002-0.2 mol / L and 0.1-3 mol / L, respectively;

[0052] (2) dissolving a carbonate (precipitant) in deionized water to form a solution B, the concentration of the carbonate solution being 0.1-2 mol / L;

[0053] (3) adding deionized water to a container, and simultaneously adding the solution A and the solution B to the deionized water under stirring at 20-50°C, the volume ratio of the deionized water to the total volume of the solutions A and B being 1:1-1:2, and maintaining the pH value of the solution at 7.5-8.5;

[0054] (4) after the completion of the addition of the solutions A and B, continuing to stir for 10-30 min, and standing for 10-30 min;

[0055] (5) filtering, washing with deionized water, and drying the precipitate to obtain a catalyst precursor, and then performing a calcination treatment to obtain a nickel / lanthanum oxide catalyst, which is reduced with H2 according to a conventional method before being used in a catalytic reaction.

[0056] Further, the nickel salt in step (1) includes any one or a combination of two or more of nickel chloride, nickel nitrate, nickel acetate, nickel sulfate, and the like, and is not limited thereto.

[0057] Further, the lanthanum salt in step (1) includes any one or a combination of two of lanthanum chloride, lanthanum nitrate, and the like, and is not limited thereto.

[0058] Further, the carbonate salt in step (2) includes any one or a combination of two of ammonium carbonate, ammonium bicarbonate, and the like, and is not limited thereto.

[0059] Further, the drying treatment in step (5) is performed at a temperature of 80 to 120°C for a time of 8 to 12 hours.

[0060] Further, the calcination treatment in step (5) is performed at a temperature of 600 to 800°C for a time of 2 to 4 hours.

[0061] Further, the reduction treatment in step (5) is performed in a hydrogen atmosphere at a temperature of 600 to 800°C for a time of 1 to 3 hours.

[0062] Another aspect of the embodiments of the present application also provides a nickel / lanthanum oxide catalyst prepared by the aforementioned method, wherein the phase of the nickel / lanthanum oxide catalyst includes monoclinic La2O2CO3 (m-La2O2CO3), hexagonal La2O2CO3 (h-La2O2CO3), La2O3, and La2NiO4, and the content of nickel element in the nickel / lanthanum oxide catalyst is 0.1 to 5.0 wt%.

[0063] Further, the content of nickel element in the nickel / lanthanum oxide catalyst is 0.2 to 4.0 wt%.

[0064] Another aspect of the embodiments of the present application also provides a use of the aforementioned nickel / lanthanum oxide catalyst in a dry reforming reaction of methane and carbon dioxide.

[0065] Another aspect of the embodiments of the present application also provides a dry reforming reaction method of methane and carbon dioxide, which includes:

[0066] Preparation of a nickel / lanthanum oxide catalyst by the aforementioned method;

[0067] Reduction treatment of the nickel / lanthanum oxide catalyst in a reducing atmosphere at 600 to 800°C for 1 to 3 hours;

[0068] Continuous input of methane and carbon dioxide into a tubular reactor provided with the nickel / lanthanum oxide catalyst subjected to the reduction treatment at a temperature of 600 to 800°C and a space velocity of 10000 to 50000 h-1. -1The reaction is carried out under the condition of the presence of a reducing atmosphere, to generate carbon monoxide and hydrogen.

[0069] Further, the reducing atmosphere includes a hydrogen atmosphere, and is not limited thereto.

[0070] Further, the molar ratio of methane to carbon dioxide is 1.0.

[0071] The technical solutions of the present application will be further described in detail below in combination with several preferred embodiments and the accompanying drawings. The embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0072] The experimental materials used in the following examples are commercially available from conventional biochemical reagent companies, unless otherwise specified.

[0073] Example 1 Preparation of a nickel / lanthanum oxide catalyst

[0074] (1) 1.80g of Ni(NO3)2·6H2O and 10.40g of La(NO3)3·6H2O were dissolved in 100ml of deionized water to form a solution A;

[0075] (2) 7.50g of NH4HCO3 was dissolved in 100ml of deionized water to form a solution B;

[0076] (3) 100ml of deionized water was added to a 500ml beaker, and the solution A and the solution B were simultaneously and slowly added to the deionized water at room temperature (20-25℃), with the stirring speed being maintained at 600rpm and the pH value of the solution being controlled at 7.9;

[0077] (4) The material containing the precipitate in step (3) was continuously stirred for 15min, and then was left to stand for 30min. The precipitate was filtered, washed with deionized water until the pH value of the filtrate was 7, and then was dried at 120℃ for 12h to obtain a catalyst precursor;

[0078] (5) The catalyst precursor was placed in a muffle furnace and calcined at 700℃ for 3h to obtain a nickel / lanthanum oxide catalyst, which was marked as NL-1, and the content of Ni element in the catalyst was 3.5wt%.

[0079] Example 2 Preparation of a nickel / lanthanum oxide catalyst

[0080] (1) 0.96g of Ni(NO3)2·6H2O and 11.76g of La(NO3)3·6H2O were dissolved in 200ml of deionized water to form a solution A;

[0081] (2) 8.30 g of NH4HCO3was dissolved in 200 ml of deionized water to form solution B;

[0082] (3) 100 ml of deionized water was added into a 1 L beaker, and solution A and solution B were simultaneously and slowly added into the deionized water at room temperature (20-25 °C) with stirring at a speed of 580 r / min, and the pH value of the solution was controlled to be 7.8;

[0083] (4) The material containing the precipitate in step (3) was continuously stirred at room temperature for 30 min, and then was allowed to stand for 30 min, and then was filtered, and the precipitate was washed with deionized water until the pH value of the filtrate was 7, and the precipitate was dried at 120 °C for 12 h to obtain a catalyst precursor;

[0084] (5) The catalyst precursor was placed in a muffle furnace and calcined at 700 °C for 3 h to obtain a nickel / lanthana catalyst, which was marked as NL-2, and the content of Ni element in the catalyst was 1.1 wt%.

[0085] Preparation of a nickel / lanthana catalyst

[0086] (1) 0.81 g of NiCl2·6H2O and 8.2 g of LaCl3·3H2O were dissolved in 100 ml of deionized water to form solution A;

[0087] (2) 8.32 g of (NH4)2CO3was dissolved in 100 ml of deionized water to form solution B;

[0088] (3) 100 ml of deionized water was added into a 500 ml beaker, and solution A and solution B were simultaneously and slowly added into the deionized water at 50 °C with stirring at a speed of 550 r / min, and the pH value of the solution was controlled to be 8.5;

[0089] (4) The material containing the precipitate in step (3) was continuously stirred at 50 °C for 20 min, and then was allowed to stand for 30 min, and then was filtered, and the precipitate was washed with deionized water until the pH value of the filtrate was 7, and the precipitate was dried at 120 °C for 12 h to obtain a catalyst precursor;

[0090] (5) The catalyst precursor was placed in a muffle furnace and calcined at 700 °C for 3 h to obtain a nickel / lanthana catalyst, which was marked as NL-3, and the content of Ni element in the catalyst was 1.8 wt%.

[0091] Preparation of a nickel / lanthana catalyst

[0092] (1) 0.288 g of Ni(NO3)2·6H2O and 15.84 g of La(NO3)3·6H2O were dissolved in 200 ml of deionized water to form solution A;

[0093] (2) Dissolve 7.23 g of (NH4)2CO3 in 200 ml of deionized water to form solution B;

[0094] (3) Add 200 ml of deionized water into a 1 L beaker, and slowly drop solution A and solution B into the deionized water at room temperature (20-25 °C) simultaneously, with the stirring speed being kept at 600 rpm, and the pH value of the solution being controlled at 7.8;

[0095] (4) Continue to stir the material containing the precipitate in step (3) at room temperature for 10 min, and then stand for 30 min. Filter, wash the precipitate with deionized water until the pH value of the filtrate is 7, and dry the precipitate at 100 °C for 12 h to obtain a catalyst precursor;

[0096] (5) Place the catalyst precursor into a muffle furnace, and calcine at 750 °C for 3 h to obtain a nickel / lanthana catalyst, which is marked as NL-4, and the content of Ni element in the catalyst is 0.2 wt%.

[0097] Example 5 Preparation of a nickel / lanthana catalyst

[0098] (1) Dissolve 0.58 g of Ni(CH3COO)2·6H2O and 9.29 g of LaCl3·3H2O in 100 ml of deionized water to form solution A;

[0099] (2) Dissolve 8.25 g of (NH4)2CO3 in 100 ml of deionized water to form solution B;

[0100] (3) Add 100 ml of deionized water into a 500 ml beaker, and slowly drop solution A and solution B into the deionized water at 40 °C simultaneously, with the stirring speed being kept at 600 rpm, and the pH value of the solution being controlled at 7.6;

[0101] (4) Continue to stir the material containing the precipitate in step (3) at 40 °C for 20 min, and then stand for 20 min. Filter, wash the precipitate with deionized water until the pH value of the filtrate is 7, and dry the precipitate at 120 °C for 12 h to obtain a catalyst precursor;

[0102] (5) Place the catalyst precursor into a muffle furnace, and calcine at 700 °C for 3 h to obtain a nickel / lanthana catalyst, which is marked as NL-5, and the content of Ni element in the catalyst is 0.9 wt%.

[0103] Comparative Example 1 Preparation of a nickel / lanthana catalyst by impregnation

[0104] (1) Dissolve 24.68 g of La(NO3)3·6H2O in 200 ml of deionized water to form solution A;

[0105] (2) 8.50 g of (NH4)2CO3 was dissolved in 200 ml of deionized water to form solution B;

[0106] (3) Solution B was slowly added to solution A at room temperature (20-25 °C), and the stirring speed was maintained at 550 rpm during the addition. After the addition was completed, the pH value of the solution was 7.6;

[0107] (4) The material containing the precipitate in step (3) was continuously stirred at room temperature for 30 min, and then was allowed to stand for 30 min. The precipitate was filtered, washed with deionized water until the pH value of the filtrate was 7, and then was dried at 120 °C for 12 h and calcined at 700 °C for 3 h to obtain La2O3 white powder;

[0108] (5) 6.0 g of the La2O3 white powder in step (4) was impregnated with a solution of 2.76 g of Ni(NO3)2-6H2O dissolved in 15 ml of deionized water at room temperature for 10 min, and then was stirred at 90 °C until the water was evaporated to obtain light green powder, which was dried at 120 °C for 12 h;

[0109] (6) The material obtained in step (5) was placed in a muffle furnace and calcined at 700 °C for 3 h to obtain a nickel / lanthana catalyst, which was marked as C-1. The content of Ni in the catalyst was 4.1 wt%.

[0110] Preparation of a nickel / lanthana catalyst by impregnation according to Comparative Example 2

[0111] (1) 14.96 g of LaCl3-3H2O was dissolved in 200 ml of deionized water to form solution A;

[0112] (2) 15.9 g of Na2CO3 was dissolved in 200 ml of deionized water to form solution B;

[0113] (3) Solution B was added to solution A at room temperature (20-25 °C), and the stirring speed was maintained at 600 rpm during the addition. After the addition was completed, the pH value of the solution was 8.5;

[0114] (4) The material containing the precipitate in step (3) was filtered, washed with deionized water until the pH value of the filtrate was 7, and then was dried at 120 °C for 12 h and calcined at 700 °C for 3 h to obtain La2O3 white powder;

[0115] (5) 6.0 g of the La2O3 white powder in step (4) was impregnated with a solution of 1.38 g of Ni(CH3COO)2-6H2O dissolved in 15 ml of deionized water at room temperature for 10 min, and then was stirred at 90 °C until the water was evaporated to obtain light green powder, which was dried at 120 °C for 12 h;

[0116] (6) The material obtained in step (5) is placed in a muffle furnace and calcined at 700°C for 3h to obtain a nickel / lanthana catalyst, marked as C-2, and the content of Ni element in the catalyst is 4.5wt%.

[0117] Comparative Example 3: Preparation of a nickel / lanthana catalyst by a precipitation method

[0118] (1) 0.44g of Ni(NO3)2·6H2O and 11.76g of La(NO3)3·6H2O are dissolved in 100ml of deionized water to form a solution A;

[0119] (2) 8.62g of NaOH is dissolved in 100ml of deionized water to form a solution B;

[0120] (3) At room temperature (20-25°C), the solution B is slowly added to the solution A, and the stirring speed is kept at 600rpm during the addition. After the addition is completed, the pH value of the solution is 9.5;

[0121] (4) The material containing the precipitate in step (3) is continuously stirred at room temperature for 10min, and then left to stand for 30min. The precipitate is filtered and washed with deionized water until the pH value of the filtrate is 7. The precipitate is dried at 120°C for 12h to obtain a catalyst precursor;

[0122] (5) The catalyst precursor is placed in a muffle furnace and calcined at 700°C for 3h to obtain a nickel / lanthana catalyst, marked as C-3, and the content of Ni in the catalyst is 0.9%.

[0123] Performance characterization:

[0124] The XRD pattern of the nickel / lanthana catalyst prepared in Examples 1-4 of the present application is shown in Figure 1 The XRD pattern of the nickel / lanthana catalyst prepared in Comparative Examples 1-3 is shown in Figure 2 From the results in Figures 1-2 It can be seen that the main phases existing in the nickel / lanthana catalyst prepared in Examples 1-4 of the present application are monoclinic La2O2CO3, hexagonal La2O2CO3, La2O3 and La2NiO4, and the difference is the proportion of each phase, which indicates that Ni exists in a highly dispersed form in the catalyst and has a strong interaction with the carrier by using the preparation method of the present application. The XRD of Comparative Examples 1-3 shows that Ni exists in the form of NiO or NiCO3 in addition to La2NiO4 in the catalyst.

[0125] The H2-TPR pattern of the catalyst prepared in Example 1 and Comparative Example 1 is shown in Figure 3As shown, it can be seen that the Ni species in the nickel / lanthana catalyst NL-1 prepared in the embodiment of the application is single, that is, almost all of the Ni has strong interaction with the carrier; while in the catalyst prepared in Comparative Example 1, there are three kinds of Ni species, NiO nanoparticles (α), Ni with weak interaction with the carrier (β) and strong interaction Ni (γ).

[0126] Preparation of nickel / lanthana catalyst of Comparative Example 4

[0127] (1) 1.80g of Ni(NO3)2·6H2O and 10.40g of La(NO3)3·6H2O were dissolved in 100ml of deionized water to form solution A;

[0128] (2) 6.80g of NH4HCO3 was dissolved in 100ml of deionized water to form solution B;

[0129] (3) 100ml of deionized water was added to a 500ml beaker, and solution A and solution B were simultaneously and slowly added to the deionized water at room temperature (20-25℃), and the stirring speed was kept at 600rpm during the process, and the pH value of the solution was controlled at 7.0;

[0130] (4) The material containing the precipitate in step (3) was continuously stirred for 15min, and then was left to stand for 30min, and then was filtered, and the precipitate was washed with deionized water for 3 times, and the precipitate was dried at 120℃ for 12h to obtain a catalyst precursor;

[0131] (5) The catalyst precursor was placed in a muffle furnace and calcined at 700℃ for 3h to obtain a nickel / lanthana catalyst, which was marked as C-4, and the content of Ni element in the catalyst was 2.6wt%.

[0132] Preparation of nickel / lanthana catalyst of Comparative Example 5

[0133] (1) 1.80g of Ni(NO3)2·6H2O and 10.40g of La(NO3)3·6H2O were dissolved in 100ml of deionized water to form solution A;

[0134] (2) 13.50g of NH4HCO3 was dissolved in 100ml of deionized water to form solution B;

[0135] (3) 100ml of deionized water was added to a 500ml beaker, and solution A and solution B were simultaneously and slowly added to the deionized water at room temperature (20-25℃), and the stirring speed was kept at 600rpm during the process, and the pH value of the solution was controlled at 9.0;

[0136] (4) The material containing the precipitate of step (3) is continuously stirred for 15 min, and then is allowed to stand for 30 min. The precipitate is filtered, washed with deionized water until the pH of the filtrate is 7, and dried at 120°C for 12 h to obtain a catalyst precursor;

[0137] (5) The catalyst precursor is placed in a muffle furnace and calcined at 700°C for 3 h to obtain a nickel / lanthanum oxide catalyst, which is marked as C-5. The content of Ni in the catalyst is 1.5 wt%.

[0138] Example 6

[0139] The catalysts prepared in Examples 1-5 and Comparative Examples 1-5 are used in a dry reforming reaction of methane and carbon dioxide. The specific reaction conditions are as follows: 0.1 g of the catalyst is diluted with 0.35 g of quartz sand and then is loaded into a fixed-bed quartz tube reactor. Before the reaction starts, the catalyst is subjected to a reduction treatment. The specific operation is as follows: under a N2 atmosphere, the catalyst is heated to 700°C, 20 mL·min - 1 of H2 is introduced, and the temperature is maintained for 2 h. Then, the H2 is turned off, and the N2 is continuously blown for 30 min. Then, methane and carbon dioxide gases are introduced for the reaction, and the molar ratio of the two is controlled to be 1. The flow rate of the feed gas is 5 mL·min -1 N2 is used as an internal standard for analysis, and the products are analyzed on-line. The test results at 1 h of reaction are shown in Table 1.

[0140] Table 1 Test results of catalyst performance

[0141]

[0142] As can be seen from the data in Table 1, under the same reaction conditions, the test results of Examples 1-5 are better than those of Comparative Examples 1-5, which indicates that the nickel / lanthanum oxide catalyst prepared by the method of the present application exhibits high catalytic activity in the dry reforming reaction of methane and carbon dioxide. This is closely related to the high dispersion of Ni and the strong interaction with the carrier.

[0143] Figures 4a-4b Further comparison is made between the catalysts prepared in Example 1 and Comparative Example 1 in terms of the change of the conversion rates of methane and carbon dioxide with the reaction time at a reaction temperature of 700°C and a space velocity of 15000 mL·g -1 .h -1 In 210 min, the conversion rates of methane and carbon dioxide of the C-1 catalyst in Comparative Example 1 show a clear downward trend, while the NL-1 catalyst in Example 1 exhibits relatively stable performance.

[0144] Figure 5TGA / DSC curves of the catalysts NL-1 in Example 1 and C-1 in Comparative Example 1 after 100 h of catalyzing the dry reforming of methane and carbon dioxide; Figures 6a-6b TEM images of the catalysts NL-1 in Example 1 and C-1 in Comparative Example 1 after 100 h of catalyzing the dry reforming of methane and carbon dioxide, respectively; Figure 5 It can be seen that the weight loss and heat release of the catalysts after 100 h of reaction at 750℃ are significantly different, the amount of carbon deposition of the C-1 catalyst in Comparative Example 1 is 20 wt%, while the NL-1 catalyst in Example 1 has almost no weight loss caused by carbon deposition, Figures 6a-6b It is further shown that the surface carbon of the C-1 catalyst in Comparative Example 1 is mainly filamentous carbon, and no obvious carbon deposition is observed for the NL-1 catalyst in Example 1. It is shown that the nickel / lanthana catalyst prepared by the method of the present application has better carbon deposition resistance and high temperature stability.

[0145] Preparation of a nickel / lanthana catalyst in Example 7

[0146] (1) 0.96 g of Ni(NO3)2·6H2O and 11.76 g of La(NO3)3·6H2O were dissolved in 200 ml of deionized water to form a solution A;

[0147] (2) 7.40 g of NH4HCO3 was dissolved in 200 ml of deionized water to form a solution B;

[0148] (3) 100 ml of deionized water was added to a 1 L beaker, and the solution A and the solution B were simultaneously and slowly added to the deionized water at room temperature (20-25℃), and the stirring speed was kept at 580 rpm during the process, and the pH value of the solution was controlled at 7.5;

[0149] (4) The material containing the precipitate in step (3) was continuously stirred at room temperature for 10 min, and then was left to stand for 30 min, and then was filtered, and the precipitate was washed with deionized water until the pH value of the filtrate was 7, and then the precipitate was dried at 80℃ for 10 h to obtain a catalyst precursor;

[0150] (5) The catalyst precursor was placed in a muffle furnace and calcined at 600℃ for 4 h to obtain a nickel / lanthana catalyst, which was marked as NL-7, and the content of Ni element in the catalyst was 0.8 wt%.

[0151] Preparation of a nickel / lanthana catalyst in Example 8

[0152] (1) 0.81 g of NiCl2·6H2O and 8.2 g of LaCl3·3H2O were dissolved in 100 ml of deionized water to form a solution A;

[0153] (2) 8.10 g of (NH4)2CO3 was dissolved in 100 ml of deionized water to form solution B;

[0154] (3) 100 ml of deionized water was added into a 500 ml beaker, and solution A and solution B were simultaneously and slowly added into the deionized water at 50°C, with the stirring speed being kept at 550 rpm, and the pH value of the solution was controlled at 8;

[0155] (4) The material containing the precipitate in step (3) was continuously stirred for 10 min, and then was left to stand for 30 min. The precipitate was filtered, washed with deionized water until the pH value of the filtrate was 7, and then was dried at 100°C for 8 h to obtain a catalyst precursor;

[0156] (5) The catalyst precursor was placed in a muffle furnace and calcined at 800°C for 2 h to obtain a nickel / lanthana catalyst, which was marked as NL-8. The content of Ni element in the catalyst was 1.7 wt%.

[0157] Preparation of a nickel / lanthana catalyst by impregnation method in Comparative Example 6

[0158] (1) La2O3 was prepared by the same method as steps (1)-(4) in Comparative Example 2;

[0159] (2) 3.42 g of the white powder of La2O3 in step (1) was impregnated with a solution of 9.09 g of Ni(NO3)2·6H2O dissolved in 20 ml of deionized water at room temperature for 10 min, and then was stirred at 90°C until the water was evaporated to obtain a light green powder, which was dried at 120°C for 12 h;

[0160] (3) The material obtained in step (2) was placed in a muffle furnace and calcined at 750°C for 2 h to obtain a nickel / lanthana catalyst, which was marked as C-6. The content of Ni element in the catalyst was 13.8 wt%.

[0161] Example 9

[0162] The catalysts prepared in Examples 7-8 and Comparative Example 6 were used in the dry reforming of methane and carbon dioxide. The specific reaction conditions were as follows: 0.1 g of the catalyst was diluted with 0.35 g of quartz sand and was loaded into a fixed-bed quartz tube reactor. Before the reaction started, the catalyst was reduced by heating to 750°C under a N2 atmosphere, and then 10 mL·min-1 of H2 was introduced for 20 min. After that, the H2 was turned off, and the N2 was continued to be introduced for 30 min. Then, the reaction was carried out by introducing methane and carbon dioxide, with the molar ratio of the two being controlled at 1. N2 was used as an internal standard for analysis, and the products were analyzed on-line. The test results after 1 h of reaction are shown in Table 2. -1 H2, 20·min -1 N2 for 2 h, H2 was turned off, and N2 was continued to be introduced for 30 min. Then, the reaction was carried out by introducing methane and carbon dioxide, with the molar ratio of the two being controlled at 1. N2 was used as an internal standard for analysis, and the products were analyzed on-line. The test results after 1 h of reaction are shown in Table 2. -1 H2, 20·min -1 N2 for 2 h, H2 was turned off, and N2 was continued to be introduced for 30 min. Then, the reaction was carried out by introducing methane and carbon dioxide, with the molar ratio of the two being controlled at 1. N2 was used as an internal standard for analysis, and the products were analyzed on-line. The test results after 1 h of reaction are shown in Table 2.

[0163] Table 2 Catalyst performance test results

[0164]

[0165] Example 10

[0166] The catalyst prepared in Examples 1-3 was used for the dry reforming of methane and carbon dioxide, and the specific reaction conditions were as follows: 0.1 g of catalyst was diluted with 0.35 g of quartz sand and loaded into a fixed-bed quartz tube reactor. Before the reaction started, the catalyst was reduced by heating to 800°C under a N2 atmosphere and passing in 10 mL·min-1of H2for 1 h, and then continuing to purge with N2for 30 min. Then, methane and carbon dioxide were passed in for reaction, with the molar ratio of the two being controlled at 1, and the flow rate of the feed gas being 5 mL·min-1. -1 H2, 20 ml·min-1 -1 N2for 1 h, the H2was turned off, and the purging with N2was continued for 30 min. Then, methane and carbon dioxide were passed in for reaction, with the molar ratio of the two being controlled at 1, and the flow rate of the feed gas being 5 mL·min-1. -1 N2was used as an internal standard for analysis, and the products were analyzed in-line. The reaction temperature was 800°C, and the space velocity of the feedstock was 30000 ml·g-1·h-1. -1 ·h -1 Good results were also obtained.

[0167] Example 11

[0168] The catalyst prepared in Examples 1-3 was used for the dry reforming of methane and carbon dioxide, and the specific reaction conditions were as follows: 0.1 g of catalyst was diluted with 0.35 g of quartz sand and loaded into a fixed-bed quartz tube reactor. Before the reaction started, the catalyst was reduced by heating to 800°C under a N2 atmosphere and passing in 10 mL·min-1of H2for 1 h, and then continuing to purge with N2for 30 min. Then, methane and carbon dioxide were passed in for reaction, with the molar ratio of the two being controlled at 1, and the flow rate of the feed gas being 5 mL·min-1. -1 H2, 20 ml·min-1 -1 N2for 1 h, the H2was turned off, and the purging with N2was continued for 30 min. Then, methane and carbon dioxide were passed in for reaction, with the molar ratio of the two being controlled at 1, and the flow rate of the feed gas being 5 mL·min-1. -1 N2was used as an internal standard for analysis, and the products were analyzed in-line. The reaction temperature was 800°C, and the space velocity of the feedstock was 30000 ml·g-1·h-1. -1 ·h -1 Good results were also obtained.

[0169] In addition, the inventors of the present case also carried out tests with other raw materials, process operations, and process conditions described in the specification, with reference to the foregoing examples, and all obtained relatively ideal results.

[0170] Aspects, embodiments, features, and examples of the present invention should be considered in all respects as illustrative only and not restrictive in any manner. The scope of the invention is only limited by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art, and the embodiments, modifications, and uses are considered within the scope of the invention as set forth in the claims.

[0171] The use of headings and chapters in the present invention is not meant to imply limitations; each chapter can apply to any aspect, embodiment, or feature of the present invention.

[0172] Throughout this invention, where compositions are described as having, containing, or including certain components, it is contemplated that the invention teachings also consist essentially of and can consist of the recited components, and where methods comprising processes are described, the invention teachings also consist essentially of and can consist of the recited process steps. Respective broad generic terms for components, compositions of matter, and methods encompass a wide variety of specific sub-generic terms or modifiers.

[0173] It should be understood that the order of steps or order for performing certain actions is immaterial so long as the present teachings remains operable. Moreover, two or more steps or actions can be conducted simultaneously.

[0174] While the present invention has been described with reference to the illustrative embodiments, those with ordinary skill in the art will appreciate that various modifications, omissions, and / or additions can be made without departing from the spirit or essential characteristics of the invention. Additionally, many modifications can be made to adapt a particular situation or material to the teachings of the present invention without departing from its scope. Thus, the present invention is not intended to be limited to the particular disclosed embodiments, but rather covers all modifications that fall within the scope of the claims. Further, unless specifically stated otherwise, any use of the terms first, second, etc. does not indicate any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.

Claims

1. A method for dry reforming reaction of methane and carbon dioxide, characterized in that... include: The nickel / lanthanum oxide catalyst was reduced at 600-800℃ for 1-3 hours in a reducing atmosphere; Furthermore, methane and carbon dioxide are continuously fed into a tubular reactor equipped with a reduced nickel / lanthanum oxide catalyst at a temperature of 600–800 °C and a space velocity of 10,000–50,000 h⁻¹. -1 The reaction proceeds under the specified conditions to produce carbon monoxide and hydrogen; wherein the molar ratio of methane to carbon dioxide is 1.

0. The preparation method of the nickel / lanthanum oxide catalyst includes: Nickel salt and lanthanum salt are dissolved in water to form a first mixed solution, and a precipitant is dissolved in water to form a precipitant solution. The first mixed solution and the precipitant solution are simultaneously added dropwise to a solvent at 20-50°C to form a mixed reaction system, and the pH of the mixed reaction system is controlled at 7.5-8.

5. The reaction is then stirred at 20-50°C for 10-30 minutes, followed by standing for 10-30 minutes to obtain a catalyst precursor. The molar ratio of nickel salt to lanthanum salt in the first mixed solution is 0.02-0.5:1; the concentration of the precipitant in the precipitant solution is 0.1-2.0 mol / L; and the volume ratio of the solvent to the sum of the first mixed solution and the precipitant solution is 1:1-1:

2. Furthermore, the catalyst precursor is calcined at 600~800℃ for 2~4h to obtain a nickel / lanthanum oxide catalyst; The nickel salt is selected from any one or a combination of two or more of nickel chloride, nickel nitrate, nickel acetate, and nickel sulfate; the lanthanum salt is selected from lanthanum chloride and / or lanthanum nitrate; and the precipitant is selected from ammonium carbonate and / or ammonium bicarbonate. The phases of the nickel / lanthanum oxide catalyst include monoclinic La2O2CO3, hexagonal La2O2CO3, La2O3 and La2NiO4, and the nickel content in the nickel / lanthanum oxide catalyst is 0.1~5.0 wt%.

2. The dry reforming reaction method according to claim 1, characterized in that: The reducing atmosphere is selected from a hydrogen atmosphere.

3. The dry reforming reaction method according to claim 1, characterized in that: The solvent includes an aqueous solution of water and / or ethanol; the concentration of the aqueous ethanol solution is less than 20 wt%.

4. The dry reforming reaction method according to claim 1, characterized in that, The preparation method of the nickel / lanthanum oxide catalyst further includes: after the settling is completed, the obtained mixture is filtered, washed and dried; the drying temperature is 80~120℃ and the time is 8~12h.

5. The dry reforming reaction method according to claim 1, characterized in that: The nickel content in the nickel / lanthanum oxide catalyst is 0.2~4.0 wt%.

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