CN1047103C - Catalyst for converting methane into synthetic gas and its process - Google Patents

Abstract

A catalyst for converting methane into synthesis gas, comprising at least one Group VIII metal element, at least one metal element capable of converting methane into synthesis gas, at least one alkali, an alkaline earth metal element, and alumina or suitable Aluminum pellets with specific surface area and pore size. The process of converting methane into synthesis gas includes making methane contact with gas containing molecular oxygen and the catalyst of the above invention at 300-800°C.

Description

Catalyst for conversion of methane to synthesis gas and use thereof

The present invention relates to a catalyst for the oxidation of methane to synthesis gas and its use.

At present, the steam reforming method of methane is used in industry to produce synthesis gas:

(1)

T(k) 800 1000

ΔH (kCal/mol) ^[1] 53.21 6.33

ΔG(kCal/mol) 53.87 -6.47 This process has some serious defects; (1) the energy consumption is serious due to the large amount of endothermic reaction (1); (2) the reaction (1) is limited by the equilibrium and needs to (3) The generated synthesis gas has a relatively high _H2 content, which is not suitable as a raw material for reactions such as synthesis of alcohols.

Syngas is produced by partial oxidation of methane:

(2)

T(k) 298 500 700 1000

ΔH(kCal/mol ^-1 ) -8.53 -7.00 -5.7 -5.37

ΔG(kCal/mol ^-1 ) -20.58 -29.34 -36.6 -52.52 Judging from the reaction and its thermodynamic data, it is entirely possible to avoid the above-mentioned problems in the steam reforming reaction. Therefore, in the past two years, people have begun to study this reaction.

British patent (Application No. 9018781.6) introduces the use of supported d-block metal or d-block metal oxide catalysts to partially oxidize methane into synthesis gas under the conditions of 650-900°C and 10-600KPa.

Recently, Patrick DFVernon et al. reported on the supported noble metal catalyst and rare earth and noble metal composite oxide Ln ₂ M ₂ O ₇ (Ln is a rare earth element, M is a noble metal element) catalyst for oxidizing methane into synthesis gas. Under the condition of 1-20atm, methane is partially oxidized into synthesis gas. These catalysts can achieve good reaction results at high temperature (1050K) (the conversion rate of methane reaches 90-95%, and the selectivities of hydrogen and carbon monoxide are both greater than 95%).

The object of the present invention is to provide a catalyst which can convert methane into synthesis gas at relatively low temperature with high conversion rate and selectivity.

The purpose of the present invention is achieved through the following technical solutions.

The catalyzer provided by the present invention has following two kinds of empirical expressions, and one is the expression of the catalyzer prepared by co-precipitation method: AaBbCcDdOx, in this catalyzer, A is a kind of selected from Ni, Pd, Pt, Ir , Rh, Ru, Co elements, B is an element selected from Cu, Ag, Zn, Cd, V, Cr, Mo, W, Mn, C is an element selected from Li, Na, K, Rb , Be, Mg, Ca, Sr, Ba elements, D is an element selected from Si, Al, Ti, Zr, wherein: b/a is 0.04-0.4, c/a is 0.4-20, d/ a is 0.5-10.

The element A of the above catalyst is preferably Ni, the element B is preferably Cu, the element C is preferably Ca, and the element D is preferably Al.

The other is the expression of the loaded catalyst prepared by impregnation: AaBbCcOx/carrier, in this catalyst, A is an element selected from Ni, Pd, Pt, Ir, Rh, Ru, Co, and B is An element selected from Cu, Ag, Zn, Cd, V, Cr, Mo, W, Mn, C is an element selected from Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba Element, D is an element selected from Si, Al, Ti, Zr, wherein: b/a is 0.04-0.4, c/a is 0.4-20, d/a is 0.5-10, and the activity in the supported catalyst The loading amount of the component is 0.01-50% (weight), and the carrier of the loaded catalyst can be a silica pellet, an aluminum oxide pellet, a silica-aluminum oxide pellet with a suitable specific surface area and pore diameter. ball.

The preferred element A of the catalyst is Ni, the preferred element B is Cu, the preferred element C is Ca, and the preferred element D is Al, and the loading amount of the active component in the supported catalyst is most preferably 1-30% (by weight) , the carrier is preferably aluminum oxide pellets.

The catalyst in the present invention can be prepared by common methods such as co-precipitation, slurry mixing or impregnation. The catalyst precursor prepared by co-precipitation, slurry mixing or impregnation method is dried at 80-150°C, and then calcined at 400-1000°C. The specific calcining temperature varies with the composition and the selected raw materials.

The process of converting methane into synthesis gas through the above-mentioned catalyst is to mix methane with a gas containing molecular oxygen before contacting with the catalyst. The range of methane/oxygen (molar ratio) is 1.9-2.5, and the gas hourly space velocity of the reaction raw material gas It is controlled at 500-5000,000hr ^-1 (under the standard state), and then contacted with the catalyst to carry out the reaction, the temperature during the reaction is 100-1000°C, and the pressure is 0.01-10 MPa.

The most suitable reaction methane/oxygen is 2.0.

The optimum temperature during the reaction is controlled at 300-800°C.

The optimum pressure during the reaction is 0.1 MPa.

The gas hourly space velocity of the reaction raw material gas is preferably 10,000-500,000hr ^-1

The raw material methane can be pure methane or methane containing a small amount of gaseous paraffins.

The gas containing molecular oxygen can be pure oxygen, or air or a mixture of air and oxygen.

Compared with the current synthesis gas produced by steam reforming of methane, the present invention has the following advantages: (1) the reaction is slightly exothermic and no longer consumes energy; ( ₂ ) the CO/H in the produced synthesis gas is close to 0.5, which is more suitable for Raw materials for synthesizing methanol and Fischer-Tropsch synthesis, (3) lower reaction temperature of 600-700°C, (4) high reaction efficiency, methane conversion rate and selectivity of carbon monoxide and hydrogen can be higher than 95%.

The following comparative examples further illustrate the catalyst of the present invention. Example 1:

Weigh Ni(NO ₃ ) ₂ 6H ₂ O 0.998g, Cu(NO ₃ ) ₂ 3H ₂ O 0.166g, Al(NO ₃ ) ₃ 9H ₂ O 3.001g, Ca(NO ₃ ) ₂ 4H ₂ O 0.041 g and dissolve them in 20 ml of water, then slowly add 10% (NH ₄ ) ₂ CO ₃ solution under stirring until the gel is completely formed; the resulting gel is washed, then dried at 110 ° C for 16 hr, air The catalyst was obtained by calcining at 750°C for 4 hours.

Take 0.2ml of 20-40 mesh catalyst and put it into a quartz tube reactor with an inner diameter of 8mm, treat it with N2 _{- H2} mixed gas (flow rate 40ml/min) containing 10% _H2 at 500°C for 1hr and then react to obtain The results are shown in Table 1:

Table 1

T(°C) XCH ₄ (%) XO ₂ (%) SCO (%) SH ₂ (%)

500 84.3 100 86.1 90.2

550 89.1 100 90.5 95.4

600 94.2 100 94.2 98.1

650 96.0 100 95.4 99.0

700 98.1 100 97.1 100 Reaction conditions: GHSV=3×10 ⁴ hr ^-1 , CH ₄ :O ₂ :N ₂ =2:1:0 Example 2:

Catalyst used in this example and pretreatment condition are all the same as embodiment 1, change the intake velocity of reaction feed gas, the reaction result of gained is as shown in table 2:

Table 2

GHSV(hr ^-1 ) XCH ₄ (%) XO ₂ (%) SCO(%) SH ₂ (%)

5.000 98.5 100 98.0 100

10.000 98.1 100 97.2 100

20.000 99.0 100 97.2 100

30.000 98.1 100 97.1 100

40.000 97.1 100 96.5 99.0

60.000 90.2 100 92.1 96.5

300.000 83.4 100 87.2 84.7 Reaction conditions: T=700°C, CH ₄ :O ₂ :N ₂ =2:1:0 Example 3:

Catalyst used in this example and pretreatment condition are all the same as embodiment 1, change the composition of reaction feed gas, the reaction result of gained is as shown in table 3:

table 3

CH ₄ : _{O 2} : N ₂ CH ₄ XO ₂ SCO SH ₂

2:1:0 98.2 100 97.0 100

2:1:2 98.2 100 97.1 100

2:1:4 99.0 100 97.0 100 Reaction conditions: T=700°C, GHSV=3×104hr ^-1 Example 4:

Weigh Ni(NO ₃ ) ₂ 6H ₂ O 0.931g, Zn(NO ₃ ) ₂ 6H ₂ O 0.076g, Ca(NO ₃ ) ₂ 4H ₂ 0.283g, Al(NO ₃ ) ₃ 9H ₂ O 3.001 g, they were dissolved in 20ml of water, and while stirring the mixed solution, 10% (NH ₄ ) ₂ CO ₃ solution was slowly added until the mixed solution completely formed a gel. The gel was washed, dried at 110°C for 16 hrs, calcined at 750°C for 4 hrs in air, and reduced at 500°C for 1 hr (10% H ₂ -N ₂ , GHSV=10,000h ^-1 ) to obtain the finished catalyst.

Get 0.2ml catalyst to carry out reaction in the reactor among the example 1, change reaction temperature obtained result and see Table 4.

Table 4

T(°C) GHSV(hr ^-1 ) XCH ₄ XO ₂ SCO SH ₂

600 30,000 78.2 100 90.1 90.3

700 30,000 84.6 100 93.2 9.21

750 30,000 89.2 100 94.6 95.0

750 60,000 91.0 100 95.2 93.8 Reaction conditions: CH ₄ :O ₂ :N ₂ =2:1:0 Example 5:

Weigh 3.60 g of Al(NO ₃ ) ₃ 9H ₂ O, dissolve it in 15 ml of water, add 10% (NH ₄ ) ₂ CO ₃ under stirring until the pH is about 8, and age the obtained gel at room temperature for 24 hours, washing. Weigh 1.98 g of Ni(NO ₃ ) ₂ ·6H ₂ O and 0.356 g of La(NO ₃ ) ₃ ·6H ₂ O, and mix them with the gel prepared above. Calcined at 750°C for 4hr. Get 0.2ml of catalyzer of 20～40 meshes, in the O of _40ml /min Airflow and 500 ℃ down treatment 1hr, the result obtained by reacting in the reactor in embodiment 1, see table 5

table 5

T(°C) XCH ₄ XO ₂ SCO SH ₂

750 96.0 100 97.0 99.0

700 90.4 100 91.2 94.8

550 78.2 100 82.4 89.5 Reaction conditions: CH ₄ : O ₂ : N ₂ =2: 1: 0, GHSV=3×104hr ^-1 Example 6:

Weigh 1.608 grams of 20-40 mesh Al ₂ O ₃ (specific surface area 168m ² /g), dissolve 1.222 grams of Ni(NO ₃ ) ₂ ·6H ₂ O in 1.6 ml, and 0.201 grams of Cu(NO ₃ ) ₂ ·3H ₂ O, 0.051 g Ca(NO ₃ ) ₂ ·4H ₂ O aqueous solution was impregnated, dried at 110°C for 16 hrs and calcined at 750°C in air for 4 hrs to prepare the catalyst.

Get 0.2ml of catalyst and place it in the reactor in Example 1, first use 40ml/min O at 500°C for _1hr , then carry out methane oxidation reaction, the reaction results are shown in Table 6

Table 6

T(°C) XCH ₄ (%) XO ₂ (%) SCO (%) SH ₂ (%)

750 90.8 100 95.2 99.0

700 93.6 100 94.0 98.0

600 90.2 100 90.1 94.6

500 82.1 100 85.7 90.1 Reaction conditions: GHSV=3×104hr ^-1 , CH ₄ :O ₂ :N ₂ =2:1:0 Example 7:

Weigh 1.397 grams of Ni(NO ₃ ) ₂ ·6H ₂ O, 0.232 grams of Cu(NO ₃ ) ₂ ·3H ₂ O, 4.20 grams of Al(NO ₃ ) ₃ ·9H ₂ O and dissolve them in 30ml of water to make a mixed solution, stir This mixture was added with 10% (NH ₄ ) ₂ CO ₃ solution until the gel was completely formed. The gel was washed and dried at 110°C for 16 hrs and calcined at 750°C for 4 hrs.

Take 0.2ml of _the above-mentioned catalyst and place it in the reactor in Example 1, first treat it with 40ml/min O at 500°C for 1hr, and then carry out the reaction. The results are shown in Table 7.

Table 7

T(℃) GHSV(hr ^-1 ) XCH ₄ (%) XO ₂ (%) SCO(%) SH ₂ (%)

700 3×104 96.8 100 96.0 100

600 3×104 91.7 100 93.2 98.0

500 3×104 84.5 100 87.0 90.8

700 6×104 92.1 100 93.8 95.6

700 3×105 84.0 100 88.0 87.2 Reaction conditions: CH ₄ : O ₂ : N ₂ =2: 1: 0 Example 8:

Weigh 1.582 grams of 20-40 mesh silicon pellets (specific surface 196m ² /g), and use 1.6ml of 1.339 grams of Ni(NO ₃ ) ₂ ·6H ₂ O, 0.225 grams of Cu(NO ₃ ) ₂ ·3H ₂ O After soaking in aqueous solution, dry at 110°C for 16hrs, and calcinate at 750°C for 4hrs to obtain the catalyst

Get 0.2ml catalyst and be placed in the reactor among the embodiment 1, the methane oxidation reaction result of gained is shown in Table 8

Table 8

T(°C) XCH ₄ (%) XO ₂ (%) SCO (%) SH ₂ (%)

750 92.1 100 92.7 95.0

700 88.6 100 89.6 91.4

600 80.1 100 83.7 86.2

500 75.4 100 80.1 80.9 Reaction conditions: GHSV=3×10 ⁴ hr ^-1 , CH ₄ :O ₂ :N ₂ =2:1:0 Example 9:

Catalyst (1) (2) is prepared by the catalyst preparation method in Example 1, catalyst (3) (4) is prepared by the catalyst preparation method in Example 6, and methane oxidation is carried out according to the reaction procedure in Example 1 , the obtained results are shown in Table 9

Table 9

No. Catalyst XCH ₄ (%) XO ₂ (%) SCO (%) SH ₂ (%)

1 CoYb _0.2 Mg _0.05 Al ₄ Ox 92.1 100 92.7 95.0

2 CoNd _0.33 Al _3.33 Ox 88.6 100 89.6 91.4

3 1%Pt-0.38%Dy ₂ O ₃ /Al ₂ O ₃ 80.1 100 83.7 86.2

4 1%Ru-0.70%Eu ₂ O ₃ /Al ₂ O ₃ 75.4 100 80.1 80.9 Reaction conditions: catalyst dosage 0.2ml, T=700℃, GHSV=3×104hr ^-1 ,

CH ₄ :O ₂ :N ₂ =2:1:0

Claims (8)

1. a catalyzer that is used for the methane conversion preparing synthetic gas is characterized in that the catalyzer expression with the coprecipitation method preparation is AaBbCcDdOx,

(1) A is the element of a kind of Ni of being selected from, Pd, Pt, Ir, Rh, Ru, Co,

(2) B is the element of a kind of Cu of being selected from, Ag, Zn, Cd, V, Cr, Mo, W, Mn,

(3) C is the element of a kind of Li of being selected from, Na, K, Rb, Be, Mg, Ca, Sr, Ba,

(4) D is the element of a kind of Si of being selected from, Al, Ti, Zr, and wherein: b/a is 0.04-0.4, and c/a is 0.4-20, and d/a is 0.5-10.

2. catalyzer as claimed in claim 1 is characterized in that elements A wherein is Ni, and element B is Cu, and Elements C is Ca, and element D is Al.

3. a catalyzer that is used for the methane conversion preparing synthetic gas is characterized in that the supported catalyst expression with immersion process for preparing is the AaBbCdOx/ carrier,

(1) A is the element of a kind of Ni of being selected from, Pd, Pt, Ir, Rh, Ru, Co,

(2) B is the element of a kind of Cu of being selected from, Ag, Zn, Cd, V, Cr, Mo, W, Mn,

(3) C is the element of a kind of Li of being selected from, Na, K, Rb, Be, Mg, Ca, Sr, Ba,

(4) D is a kind of element that is selected from Si, Al, Ti, Zr,

(5) catalyst-supporting support be silicon-dioxide bead or aluminium sesquioxide bead or, silicon-dioxide-aluminium sesquioxide bead, wherein, b/a is 0.04-0.4, and c/a is 0.4-20, d/a is 0.5-10, and the loading of active ingredient is 0.01-50% (weight) in the supported catalyst.

4. catalyzer as claimed in claim 3 is characterized in that elements A wherein is Ni, and element B is Cu, and Elements C is Ca, and D is Al.

5. catalyzer as claimed in claim 3 is characterized in that catalyst-supporting support wherein is Al ₂O ₃Bead.

6. catalyzer as claimed in claim 3 is characterized in that supported catalyst active principle loading wherein is 1-30% (weight).

7. the purposes of the catalyzer of claim 1 is characterized in that under 300-800 ℃ temperature, and the gas mixture that the methane and the gas of molecule-containing keto are made into contacts with the catalyzer of claim 1-2.

8. the purposes of the catalyzer of claim 3 is characterized in that under 300-800 ℃ temperature, and the gas mixture that the methane and the gas of molecule-containing keto are made into contacts with the catalyzer of claim 3-6.