CN1676218A - Cerium-titanium composite oxide supported metal catalyst, preparation method and application - Google Patents

Abstract

The present invention relates to a catalyst which uses cerium titanium composite oxide as carrier for loading nickel or platinum o r cobalt active component, the mass content of said active component is 0.5%-40%. Its preparation method includes the following steps: directly mixing Ce(NO3)3 and TiCl4 or adding H2O2 to obtain cerium titanium solution; or mixing (NH4)2Ce(No3)6 and TiCl4 to obtain cerium titanium Y solution; adding ammonia water into the cerium titanium solution, mixing, stirring, aging, separating, washing filter cake, separating, drying, calcining so as to obtain cerium titanium composite oxide carrier; impregnating said carrier with solution of Ni(NO3)2, H2PtCl6 or Co(NO3)2, separating, drying and calcining so as to obtain the invented catalyst.

Description

Cerium-titanium composite oxide supported metal catalyst, preparation method and application

technical field

The invention relates to a cerium-titanium composite oxide-supported metal catalyst, a preparation method and application thereof, and belongs to the technology of supported metal catalysts for hydrocarbon reforming and partial oxidation.

Background technique

The main existing catalysts for hydrocarbon reforming and partial oxidation are:

(1) Catalyst with nickel (Ni) as the active component

This type of catalyst uses nickel as the active component, and the reported supports include Al ₂ O ₃ , composite oxides of silicon and aluminum, SiO ₂ , TiO ₂ , MgO, ZrO ₂ and other metal oxides or CeO ₂ -ZrO ₂ , Al ₂ O ₃ -MgO and other composite metal oxides. Such as Ni/Al ₂ O ₃ ^[1] , Ni/TiO ₂ ^[2] , Ni/CeO ₂ , Ni/ZrO ₂ , Ni/SiO ₂ ^[3] , Cu, Co, Fe, Ni/ZrO ₂ ^[4] , Ni/MgO ^[5] and so on. These catalysts all have high initial activity and selectivity, but due to the formation of carbon deposits or hot spots, the catalysts are not stable and have a short service life. Using composite oxides as supports or adding other substances will effectively improve the performance of the catalyst. Reports include Ni/CeO ₂ -ZrO ₂ ^[6] , Ni/Al ₂ O ₃ -CeO ₂ ^[7] , Ni/CaO-CeO ₂ -ZrO ₂ ^[8] and so on. Ni and CeO ₂ -ZrO ₂ have a strong interaction, and CeO ₂ is easy to reduce so that mobile oxygen can be generated during the reforming process, and the decoking activity is very high through the participation of lattice oxygen in the reaction. The addition of CaO and _ZrO2 to _CeO2 can effectively improve the partial oxidation activity of _CH4 and reduce the carbon deposition, but the stability and activity still need to be improved.

(2) Noble metal catalyst

Such catalysts include Pt, Pd, Ru, Rh, Ir and other noble metals supported on Al ₂ O ₃ , CeO ₂ , MgO, CeO ₂ -ZrO ₂ and other oxides or composite metal oxides. These catalysts exhibit good activity and selectivity in both reforming and partial oxidation. Pt/Al ₂ O ₃ , Rh/SiO ₂ , Pd/CeO _{2 ,} etc. have high activity in methane reforming and partial oxidation, Pd/CeO ₂ , Pt/CeO ₂ , Rh/Al ₂ O ₃ , Pd/γ-Al ₂ O ₃ , Ir/CeO ₂ , etc. also exhibit high activity and selectivity in the reforming of ethanol, and are generally more active than non-noble metal catalysts, with strong coking resistance and good reaction stability . Bhattacharya et al. prepared a series of supported Pd catalysts. The supports were IIIA group, IVA group and La series metal oxides and _γ -Al ₂ O ₃ and SiO ₂ . The selectivity of CO on the catalyst can reach more than 99%, and the conversion rate of _CH4 is between 33.4% and 66.9%. The catalyst given by the international patent supports Pt group metals on La series, IIB group, IV group metal oxides and _Al2 On O ₃ , it also has high CO selectivity. Schmidt et al. used monolithic ceramic materials to support Rh, Pt, Ir, Pd, Pd/La ₂ O ₃ as catalysts, and carried out POM reaction under certain conditions. The results pointed out that Rh has the best catalytic performance; Buyevskaya et al. proposed to use Rh (unsupported) or a catalytic system loaded on γ-Al ₂ O ₃ for research, for partial oxidation of methane, Rh loaded on γ-Al ₂ O ₃ In other words, Rh ions can be stabilized by the carrier, and the performance is better.

However, when precious metals are used as catalyst active components, the common disadvantage is that the content of CO in the reaction product is too high. When used in PEMFC fuel cells, it must go through complicated procedures to reduce its content to 10-30ppm, and precious metals are expensive. It is difficult to implement in popularization.

references

[1] Leroi, Pascaline; Madani, Behrang; Pham-Huu, Cuong; Ledoux, Marc-Jacques; Savin-Poncet, Sabine Catalysis Today 53-58, 91-92 (2004)

[2] Yan, Q.G.; Weng, W.Z.; Wan, H.L.; Toghiani, H.; Toghiani, R.K.; Pittman Jr, C.U.

[3] Matsumura, Yasuyuki; Nakamori, Toshie

Applied Catalysis A: General 258(1), 107-114(2004)

[4] Acta Catalytica, 20(1): 73-75(1999)

[5] Fujimoto, K.; Yamazaki, O. Tomishige, K. Applied Catalysis A: General

content invention

The object of the present invention is to provide a metal catalyst supported by cerium-titanium composite oxide and its preparation method and application. The catalyst has high activity, high selectivity and good stability for reforming and partial oxidation of hydrocarbons. The preparation method is simple in process.

The present invention is achieved through the following technical scheme, a metal catalyst supported by cerium-titanium composite oxide, characterized in that: the catalyst uses cerium and titanium composite oxide as a carrier, and nickel or platinum or cobalt active components are loaded on it , the mass content of the active ingredient (calculated according to the oxide content) is 0.5% to 40%.

The preparation method of above-mentioned catalyst is characterized in that comprising following process:

Preparation of the carrier:

Ce(NO ₂ ) ₃ and TiCl ₄ are used as raw materials, and the atomic ratio of cerium and titanium (Ce/Ti) is 0.1 to 0.9, and the cerium-titanium solution is directly mixed; or H ₂ O ₂ and Ce(NO ₃ ) ₃ The molar ratio is 0.5 to 2.0, adding H ₂ O ₂ to mix and prepare cerium-titanium solution; or use (NH ₄ ) ₂ Ce(NO ₃ ) ₆ and TiCl ₄ as raw materials, and according to the atomic ratio of cerium-titanium (Ce/Ti) 0.1-0.9, mix and prepare cerium-titanium solution; add 2%-28% ammonia water to the cerium-titanium mixed solution, control the pH value at 7.5-11.5, mix and stir for 10 minutes to 4 hours, and then age (stand) for 1 hour After 40 hours, solid-liquid separation is carried out by filtration. The solid (precipitate) material obtained after the filter cake is washed and separated by deionized water and ethanol is then dried at 50°C to 180°C. ℃ for 2-6 hours to obtain cerium-titanium composite oxide as a carrier.

Loaded active ingredients:

The prepared cerium-titanium composite oxide support is immersed in a solution of Ni(NO ₃ ) ₂ , H ₂ PtCl ₆ or Co(NO ₃ ) ₂ with a mass content of 0.5% to 40% (calculated by oxide content) 12 hours to 36 hours, then separate the solid, dry at 50°C to 180°C for 10 to 30 hours, and then calcinate at 600°C to 900°C for 1 hour to 6 hours to obtain a cerium-titanium composite oxide carrier loaded with nickel, or It is a catalyst loaded with platinum, or a catalyst loaded with cobalt.

The catalysts mentioned above are used in reforming and partial oxidation reactions of hydrocarbons.

The advantages of the present invention are that the preparation and production process is simple and easy, and the high dispersion of the prepared nickel catalyst can reduce carbon deposits, and it has high activity, high selectivity and good stability when used in hydrocarbon reforming and partial oxidation reactions .

Description of drawings:

Fig. 1 is one of the catalytic performance test result of catalyst among the example 1: _CH conversion ratio curve with temperature;

Fig. 2 is the second of the catalytic performance test result of catalyst in example 1: CO selectivity curve with temperature;

Fig. 3 is the third of the catalytic performance test result of catalyst in example 1: _H selectivity curve with temperature;

Fig. 4 is NiO10wt%/Ce _0.5 Ti _0.5 O ₂ -700 catalyst 100 hour stability change curve in example 1;

Fig. 5 is the X-ray diffraction pattern of the NiO10wt%/Ce _0.5 Ti _0.5 O ₂ catalyst obtained at the temperature of 300°C and 700°C, 300°C and 800°C, 300°C and 900°C for 2h respectively in Example 1, Spectrum A The calcination temperature of B is 300°C and 700°C, the calcination temperature of B spectrum is 300°C and 800°C, and the calcination temperature of C spectrum is 300°C and 900°C;

Fig. 6 is the energy test result of catalyst in example 2: methane conversion rate, carbon monoxide selectivity, hydrogen selectivity change curve;

Fig. 7 is the X-ray diffractogram of catalyst in the example 2;

Detailed ways

Example 1: Preparation of 10wt% NiO/Ce _0.5 Ti _0.5 O ₂ catalysts calcined at a series of temperatures by coprecipitation-impregnation method Preparation process:

Carrier preparation: (1) Preparation of 0.5mol/LCe(NO ₃ ) ₃ solution: accurately weigh 75.55g Ce ₂ (CO ₃ ) ₃ ·8H ₂ O with a balance, and measure 50ml of 15mol/L nitric acid with a graduated cylinder. Slowly add nitric acid dropwise into Ce ₂ (CO ₃ ) ₃ ·8H ₂ O, and keep stirring until dissolved. Then the dissolved Ce(NO ₃ ) ₃ solution was transferred to a 500ml volumetric flask, and distilled water was added to prepare a 0.5mol/LCe(NO ₃ ) ₃ solution. (2) Preparation of TiCl ₄ solution: Measure 23.4ml TiCl ₄ hydrochloric acid solution with a graduated cylinder and place it in a fume hood, slowly add distilled water dropwise to the solution, and the TiCl ₄ solution will decompose under the action of water, releasing a large amount of white smoke and producing simultaneously yellow solid. Continue to add distilled water dropwise to the yellow solid until it dissolves, resulting in a light yellow solution. (3) Take 428.6 ml of 0.5 mol/L Ce(NO ₃ ) ₃ solution and the TiCl ₄ solution prepared in (2) to uniformly mix the solution. Take an appropriate amount of NH ₃ ·H ₂ O and the prepared Ce and Ti mixed solution and titrate them into a certain amount of water with a pH value between 7-13, while stirring continuously at a stirring rate of about 100N/min. After the titration was complete, stirring was continued for 4 hours. Leave to age at room temperature for 24 hours. Then the aged precipitate was washed and filtered with suction. When washing, wash with distilled water three times, each time with 400ml of distilled water, accompanied by stirring; after washing with water, wash twice with ethanol, each time with 100ml of ethanol, accompanied by stirring. The filter cake after washing and suction filtration was placed in a constant temperature oven at 80° C. for drying for 24 hours. Place the filter cake dried at 80°C at room temperature to cool and weigh out a certain amount of sample for later use.

Loading active components: Weigh out 20 g of the above-prepared carrier sample (calculated as hydroxide), and then convert it into oxide mass. Weigh 5.779g Ni(NO ₃ ) ₂ ·6H ₂ O according to the converted oxide mass and dissolve it in an appropriate amount of distilled water. Then dip the above weighed sample into it and stir for 20-30min. The impregnated samples were left to stand overnight at room temperature, and then dried in a constant temperature oven at 80°C for 12 hours. Then the samples were divided into three parts and calcined at 300°C and 700°C, 300°C and 800°C, and 300°C and 900°C for 2 hours respectively. That is, the mass content of 10% NiO/Ce _0.5 Ti _0.5 O ₂ calcined at different calcination temperatures was obtained.

Catalyst performance test: The performance test of the catalyst is carried out on a fixed-bed quartz tube reactor under normal pressure, and the specification of the quartz tube reactor is Φ10×2. The dosage of the experimental sample is 200mg, the particle size is 40-60 mesh, and the space velocity of the feed gas is 55,200ml/hgcat. The raw material composition is: 20vol.% CH ₄ , 10vol.% O ₂ , 70vol.% N ₂ . The sample was heated from room temperature to 650°C, purged with N ₂ , reduced with 5vol% H ₂ -Ar at 650°C for 30min, and changed to reaction gas after reduction. Under reaction gas conditions, the temperature was changed to the reaction temperature. The reaction starts at 650°C and sets a temperature point every 50°C to 850°C. Each temperature point was reacted for 1 hour. SP-2100 gas chromatography on-line analysis, 5A molecular sieve column and GDX-502 column, TCD detection.

The catalytic performance test result of the prepared catalyst of performance test result example 1 is shown in Fig. 1 below, 2, 3, 4:

From the results, it can be concluded that the catalysts calcined at 300°C and 700°C have the best activity and selectivity;

Stability test test: The performance test of the catalyst is carried out on a fixed-bed quartz tube reactor under normal pressure, and the specification of the quartz tube reactor is Φ10×2. The dosage of the experimental sample is 200mg, the particle size is 40-60 mesh, and the space velocity of the feed gas is 55,200ml/hgcat. The raw material composition is: 20vol% CH ₄ , 10vol% O ₂ , 70vol% N ₂ . The sample was heated from room temperature to 650°C, purged with N ₂ , reduced with 5vol.% H ₂ -Ar at 650°C for 30min, and changed to reaction gas after reduction. Under reaction gas conditions, the temperature was changed to 750°C. Sample collection was started at constant temperature for 1 hour. SP-2100 gas chromatography on-line analysis, 5A molecular sieve column and GDX-502 column, TCD detection.

The stability test result of the catalyst prepared by example 1 is shown in Fig. 5 below:

Example 2: Co-precipitation-dipping method to prepare 10% NiO/Ce _0.15 Ti _0.85 O ₂ catalyst with mass content roasted at 700°C. Preparation process:

Carrier preparation: (1) Preparation of _TiCl4 solution: Measure _8.9mlTiCl4 hydrochloric acid solution with a graduated cylinder and place it in a fume hood, slowly add distilled water dropwise to the solution, and the _TiCl4 solution will decompose under the action of water, releasing a large amount of white Smoke also produced a yellow solid. Continue to add distilled water dropwise to the yellow solid until it dissolves, resulting in a light yellow solution. (2) Take 28.8ml of 0.5mol/L Ce(NO ₃ ) ₃ solution and the TiCl ₄ solution prepared in (1) to uniformly mix the solution. The remaining steps are the same as before.

Loading active components: Weigh out 10 g of the above-prepared carrier sample (calculated as hydroxide), and then convert it into oxide mass. Weigh 3.608g Ni(NO ₃ ) ₂ ·6H ₂ O according to the converted oxide mass and dissolve it in an appropriate amount of distilled water. Then dip the above weighed sample into it and stir for 20-30min. The impregnated samples were left to stand overnight at room temperature, and then dried in a constant temperature oven at 80°C for 12 hours. The samples were fired at 300°C and 700°C for 2 hours, respectively. That is _, NiO10wt%/ _{Ce0.15Ti0.85O2 was} obtained. Denote as I-N10CT4-700 respectively. The roasted samples were ground into 40-60 mesh particles for catalytic performance testing.

Catalyst performance test is the same as Example 1; performance test results: as shown in Figures 6 and 7.

Example 3: Preparation of 1wt% Pt/Ce _0.15 Ti _0.85 O ₂ catalyst calcined at 700°C by coprecipitation-impregnation method Preparation method:

Carrier preparation: (1) Preparation of _TiCl4 solution: Measure _8.9mlTiCl4 hydrochloric acid solution with a graduated cylinder and place it in a fume hood, slowly add distilled water dropwise to the solution, and the _TiCl4 solution will decompose under the action of water, releasing a large amount of white Smoke also produced a yellow solid. Continue to add distilled water dropwise to the yellow solid until it dissolves, resulting in a light yellow solution. (2) Take 28.8ml of 0.5mol/L Ce(NO ₃ ) ₃ solution and the TiCl ₄ solution prepared in (1) to uniformly mix the solution. The remaining steps are the same as before.

Loading active components: Weigh out 10 g of the above-prepared carrier sample (calculated as hydroxide), and then convert it into oxide mass. Take 8.2ml of 0.005mol/L H ₂ PtCl ₆ solution according to the converted oxide mass. Immerse the carrier sample in it and stir for 20-30min. The impregnated samples were left to stand overnight at room temperature, and then dried in a constant temperature oven at 80°C for 12 hours. Then bake at 300°C and 700°C for 2 hours respectively. That is, Pt 10wt%/Ce _0.15 Ti _0.85 O ₂ calcined at different calcination temperatures were obtained.

Catalyst performance test is the same as example 1.

Example 4: Preparation of 10wt% CoO/Ce _0.15 Ti _0.85 O ₂ catalyst calcined at 700°C by coprecipitation-impregnation method Preparation method:

Carrier preparation: (1) Preparation of _TiCl4 solution: Measure _8.9mlTiCl4 hydrochloric acid solution with a graduated cylinder and place it in a fume hood, slowly add distilled water dropwise to the solution, and the _TiCl4 solution will decompose under the action of water, releasing a large amount of white Smoke also produced a yellow solid. Continue to add distilled water dropwise to the yellow solid until it dissolves, resulting in a pale yellow solution. (2) Take 28.8ml of 0.5mol/L Ce(NO ₃ ) ₃ solution and the TiCl ₄ solution prepared in (1) to uniformly mix the solution. The remaining steps are the same as before.

Loading active components: Weigh out 10 g of the above-prepared carrier sample (calculated as hydroxide), and then convert it into oxide mass. Take 21.4ml of 0.5mol/LCo(NO ₃ ) ₂ solution according to the converted oxide mass. The above weighed carrier sample is immersed in it and stirred for 20-30min. The impregnated samples were left to stand overnight at room temperature, and then dried in a constant temperature oven at 80°C for 12 hours. Then bake at 300°C and 700°C for 2 hours respectively. That is, CoO10wt%/Ce _0.15 Ti _0.85 O ₂ calcined at different calcination temperatures can be obtained.

Catalyst performance test is the same as example 1.

Claims (3)

1. the catalyst of a cerium-titanium composite oxide-carried metal, it is characterized in that: this catalyst is a carrier with the cerium-titanium composite oxide, nickel-loaded or platinum or cobalt active component on it, the mass content of active component is 0.5%～40%.

2. catalyst method for preparing the described cerium-titanium composite oxide-carried metal of claim 1 is characterized in that comprising following process:

1) preparation of carrier:

With Ce (NO ₃) ₃And TiCl ₄Be raw material, and be 0.1～0.9, directly mixed preparing cerium titanium solution by the atomic ratio (Ce/Ti) of cerium titanium; Or press H ₂O ₂With Ce (NO ₃) ₃Mol ratio be 0.5～2.0, add H ₂O ₂Mixed preparing cerium titanium solution; Or with (NH ₄) ₂Ce (NO ₃) ₆And TiCl ₄Be raw material, and be 0.1～0.9, mixed preparing cerium titanium solution by the atomic ratio of cerium titanium; Adding mass percent to cerium titanium mixed solution is 2%～28% ammoniacal liquor, control pH value is 7.5～11.5, mix and stirred 10 minutes to 4 hours, aging 1 hour to 40 hours then, carry out Separation of Solid and Liquid again, filter cake obtains solid matter after deionized water and ethanol washing separation, then 50 ℃～180 ℃ dryings, dried solid was calcined 2～6 hours at 350 ℃ to 900 ℃, and obtaining cerium-titanium composite oxide is carrier; Or dried solid is directly as carrier;

2) load active component:

With the cerium-titanium composite oxide carrier that step 1) makes, dipping is 0.5%～40% Ni (NO by oxide calculated mass content ₃) ₂, H ₂PtCl ₆Or Co (NO ₃) ₂Soaked in the solution 12 hours～36 hours, and isolated solid then, 50 ℃～180 ℃ dryings after 10～30 hours, in 600 ℃～900 ℃ calcinings 1 hour～6 hours, obtain cerium-titanium composite oxide carrier loaded nickel, or load platinum, or load the catalyst of cobalt.

3. the Application of Catalyst of the described cerium-titanium composite oxide-carried metal of claim 1 is characterised in that the reformation and the partial oxidation reaction that are used for hydrocarbon.

Images