CN116060014A - Novel hydrocarbon steam conversion catalyst and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical fields of petrochemical industry, natural gasification technology and catalyst manufacturing engineering, and particularly relates to a novel hydrocarbon steam conversion catalyst and a preparation method thereof. The novel hydrocarbon steam conversion catalyst of the invention adopts perovskite type active component, acid calcium cement and alpha-Al ₂ O ₃ The potassium, magnesium and nickel are prepared into active ingredients with stable perovskite structures, so that the potassium loss in the catalyst can be reduced; and by introducing a structural additive with a heat stabilization effect or loading the perovskite type metal oxide catalyst on a proper carrier, the dispersity of the catalyst can be increased, the heat stability of the catalyst can be improved, and the catalyst has good activity.

Description

A Novel Hydrocarbon Steam Reforming Catalyst and Its Preparation Method and Application

technical field

The invention belongs to the technical fields of petrochemical industry, natural gas chemical industry technology and catalyst manufacturing engineering, and specifically relates to a novel hydrocarbon steam reforming catalyst, and further discloses its preparation method.

Background technique

Hydrocarbon steam reforming is a method commonly used by refining and chemical enterprises at home and abroad to produce hydrogen and synthesis gas. Among them, the light hydrocarbon steam reforming method uses natural gas, liquefied petroleum gas, refinery gas or naphtha as raw materials. In the steam reforming process of hydrocarbons, at a certain water-to-carbon ratio, coking in the steam reforming process of hydrocarbons is an inevitable thermodynamic process. Therefore, in order to prevent carbon deposition on the catalyst during steam reforming of hydrocarbons, it is required In addition to having good activity, strength and stability, it also has strong anti-coking performance.

At present, there are two main ways to solve the problem of anti-coking of conversion catalysts at home and abroad: one is to improve the low-temperature activity of the catalyst as much as possible, and at the same time use an alkaline carrier; the other is to add potassium salt to promote the formation of carbon by potassium. Gasification carbon removal reaction. However, although the addition of commonly used potassium salt can improve the anti-coking performance of the catalyst, due to the disadvantage of easy loss of potassium salt, the loss of potassium will reduce the stability of the catalyst to a certain extent, and the loss of potassium is easy to accumulate in the waste boiler system , Corrosion and scaling clog the waste boiler system.

At present, the perovskite-type composite metal oxide (general formula ABO ₃ ) catalyst is a catalyst with great development potential. It is often used as a catalytic combustion reaction and photocatalytic material, and it is not commonly used as a hydrocarbon steam reforming reaction. However, although perovskite-type metal oxide catalysts have good stability, there are still problems such as low specific surface area and easy sintering at high temperatures, which limit the application of perovskite-type catalysts.

Contents of the invention

For this reason, the technical problem to be solved by the present invention is to provide a hydrocarbon steam reforming catalyst, which has the advantages of high anti-coking performance, strong potassium fixing ability, good thermal stability and good activity;

The second technical problem to be solved by the present invention is to provide the preparation method of the above-mentioned catalyst, the method adopts the sol-gel method to make slurry to load the active component gel on the alumina, and the active component gel is roasted to generate perovskite structure, so that the active components are uniformly dispersed on the alumina carrier, effectively improving the overall performance of the catalyst.

In order to solve the above-mentioned technical problems, a novel hydrocarbon steam reforming catalyst according to the present invention, the catalyst includes the following components in mass content based on the total amount:

Perovskite active component 35-45wt%;

Calcium aluminate cement 15-25wt%;

α-Al ₂ O ₃ balance;

The perovskite active component has a structure represented by the general formula K _x Mg _1-x NiO ₃ , where x=0.1-0.2.

Specifically, the pore volume of the catalyst is 0.30-0.50mL/g, the bulk density is 0.85-0.95Kg/L, and the lateral pressure strength of the catalyst is greater than 250N/particle.

Specifically, the appearance of the catalyst can be in the shape of a four-hole column, a seven-hole column, a Raschig ring, a seven-rib wheel, and the like.

The invention also discloses a method for preparing the novel hydrocarbon steam reforming catalyst, comprising the following steps:

(1) Take a selected amount of the α-Al ₂ O ₃ and add citric acid, and add water to fully mix to form a liquid mixture for subsequent use;

(2) According to the selected proportion of the perovskite-type active components, potassium nitrate, magnesium nitrate and nickel nitrate are added to form a solution for subsequent use;

(3) Drop the solution obtained in step (2) into the liquid mixture obtained in step (1), mix well and heat to evaporate water, so that it gradually becomes a gel form;

(4) drying and roasting the gel obtained in step (3) to obtain a catalyst semi-finished product for subsequent use;

(5) Pulverize the obtained catalyst semi-finished product, add a selected amount of the calcium acid cement and mix well, continue to add water and mix well, then carry out compression molding, curing, to get final product.

Specifically, the molar ratio of the amount of citric acid added in the step (1) to the total amount of nitrates in the step (2) is 1:2-4.

Specifically, in the step (4), the temperature of the drying step is 80-150°C.

Specifically, in the step (4), the temperature of the calcination step is 500-1000° C., and the calcination time is 4-8 hours. Preferably, the calcination temperature is 700-850° C., and the calcination time is 5-10 hours. The temperature affects the formation of the active component perovskite.

Specifically, in the step (5), the curing step is steam curing, and the curing time is 24-36 hours.

The invention also discloses the application of the catalyst in hydrocarbon steam reforming process.

Specifically, the catalyst is suitable for hydrocarbon steam reforming process with reformer inlet temperature of 430-600°C, outlet temperature of 700-850°C, converted carbon space velocity of 8000h ^-1 , water-to-carbon ratio of 1.2-3.5, and pressure of 2.0-4.0MPa , for the production of hydrogen or synthesis gas. Under the above conditions, the potassium loss rate of the catalyst is less than 3%.

The novel hydrocarbon steam reforming catalyst of the present invention uses perovskite-type active components, calcium acid cement and α- _Al2O3 as active components, and is made of potassium, magnesium and _nickel into a stable perovskite structure. The active ingredient can reduce the loss of potassium in the catalyst; and by introducing a structural aid with thermal stability or loading the perovskite metal oxide catalyst on an appropriate carrier, the dispersion of the catalyst can be increased and its thermal stability can be improved properties, and the catalyst has good activity.

The novel hydrocarbon steam reforming catalyst described in the present invention utilizes conventional potassium element for anti-coking, on the one hand, potassium will catalyze the reaction between C and _H2O , and accelerate the efficiency of carbon removal; on the other hand, potassium can also neutralize The acid sites of the catalyst, thereby slowing down the formation of char. Adding an appropriate amount of K content to the catalyst of the present invention can make use of potassium to present alkalinity, effectively neutralize the acid center of the catalyst, effectively promote the gasification reaction of water vapor and charcoal, and effectively prevent the It is beneficial for the acidic center of the catalyst to catalyze the process of carbon chain cracking of higher hydrocarbons into CH _x free radicals, effectively ensuring the conversion activity of the catalyst. At the same time, the magnesium contained in the catalyst of the present invention is alkaline and has strong water absorption, so it can have a certain anti-coking effect, and the addition of magnesium can also reduce the addition of potassium in the catalyst to ensure that the potassium content is moderate And the effect is better.

The catalyst described in the present invention has the advantages of strong potassium-fixing ability, high anti-coking performance and ^high activity _. Hydrocarbon steam reforming catalysis is carried out under the process conditions of /C (mol/mol) of 1.5, bed inlet temperature of 430°C, and bed outlet temperature of 720°C, which has better activity and stability.

Description of drawings

In order to make the content of the present invention more clearly understood, the present invention will be described in further detail below according to the specific embodiments of the present invention and in conjunction with the accompanying drawings, wherein,

Fig. 1 is the XRD pattern of the catalyst prepared by the embodiment of the present invention 1;

Fig. 2 is the schematic flow chart of the small-scale pressurized activity evaluation device that is used for catalyst activity evaluation;

Reference numerals in the figure represent: 1-oil metering pump, 2-water metering pump, 3-vaporizer, 4-mixer, 5-tubular reactor, 6-condenser, 7-separator, 8-pressure regulator device, 9-wet flowmeter.

Detailed ways

In order to enable those skilled in the art to understand the technical solution of the present invention more clearly, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

Example 1

The preparation method of the hydrocarbon steam reforming catalyst described in this embodiment comprises the following steps:

(1) Weigh 192g of citric acid and 142.5g of alumina into 500mL of deionized water, mix well, and set aside;

(2) Weigh 20.2g of potassium nitrate, 205.1g of magnesium nitrate, and 290.7g of nickel nitrate into 1000mL of deionized water, fully mix to form a solution, and set aside;

(3) Under stirring, add the solution in step (2) dropwise to the liquid mixture obtained in step (1), and mix thoroughly; then heat the obtained liquid mixture to evaporate water, so that it gradually becomes a gel ;

(4) Put the formed gel into a drying oven, and after drying at 120°C, continue to put it into an electric furnace for roasting at 750°C for 6 hours to obtain a semi-finished catalyst;

(5) The semi-finished product obtained by the above-mentioned roasting was crushed, and 69.1 g of calcium aluminate cement and an appropriate amount of water were added to mix evenly, and then pressed and molded. After steam curing for 24 hours, the finished catalyst cat-1 was obtained.

After testing, the active component of the catalyst is K _0.2 Mg _0.8 NiO ₃ , and its XRD pattern is shown in FIG. 1 .

Example 2

The preparation method of the hydrocarbon steam reforming catalyst described in this embodiment comprises the following steps:

(1) Weigh 96g of citric acid and 102.5 alumina into 500mL of deionized water, mix well, and set aside;

(2) Weigh 10.1g of potassium nitrate, 230.8g of magnesium nitrate, and 290.7g of nickel nitrate and add them to 1000mL of deionized water to form a solution for subsequent use;

(3) In a stirring state, add the solution formed in step (2) dropwise to the liquid mixture obtained in step (1), and mix well; then heat the obtained liquid mixture to evaporate water, so that it gradually becomes gel;

(4) Put the obtained gel into a drying oven, dry it at 120°C, and then put it into an electric furnace and roast it at 800°C for 8 hours to obtain a semi-finished catalyst;

(5) Pulverize the catalyst semi-finished product obtained by the above-mentioned roasting, and add 58.6g of calcium aluminate cement and appropriate amount of water to mix evenly, and press molding, after steam curing for 24 hours, the finished catalyst cat-2 is obtained, the active component of the catalyst It is K _0.1 Mg _0.9 NiO ₃ .

Example 3

The preparation method of the hydrocarbon steam reforming catalyst described in this embodiment comprises the following steps:

(1) Weigh 150g of citric acid and 169.5g of aluminum oxide into 500mL of deionized water, mix well, and set aside;

(2) Weigh 10.1g of potassium nitrate, 230.8g of magnesium nitrate, and 290.7g of nickel nitrate and add them to 1000mL of deionized water to form a solution for subsequent use;

(3) In the stirring state, add the solution obtained in step (2) dropwise to the liquid mixture obtained in step (1), and mix thoroughly; glue;

(4) Put the obtained gel into a drying oven, dry it at 120°C, and then put it into an electric furnace and roast it at 800°C for 8 hours to obtain a semi-finished catalyst;

(5) After pulverizing the catalyst semi-finished product obtained by the above-mentioned roasting, add 75.3g of calcium aluminate cement and appropriate amount of water to mix evenly, and press molding, after steam curing for 24h, the finished catalyst cat-3 is obtained, the active group of the catalyst is Divided into K _0.1 Mg _0.9 NiO ₃ .

Example 4

The preparation method of the hydrocarbon steam reforming catalyst described in this embodiment comprises the following steps:

(1) Weigh 135g of citric acid and 133g of aluminum oxide into 500mL of deionized water, mix well, and set aside;

(2) Take by weighing 15.2g potassium nitrate, 217.9g magnesium nitrate, 290.7g nickel nitrate and join in 1000mL deionized water to make a solution for subsequent use;

(3) In the stirring state, add the solution obtained in step (2) dropwise to the liquid mixture obtained in step (1), and mix well; then heat the obtained liquid mixture to evaporate water, so that it gradually becomes condensed glue;

(4) Put the obtained gel into a drying oven for drying at 120° C., and then put it into an electric furnace for roasting at 850° C. for 6 hours to obtain a semi-finished catalyst;

(5) After pulverizing the catalyst semi-finished product obtained by roasting, add 66.5g of calcium aluminate cement and appropriate amount of water to mix evenly, and press molding, after steam curing for 24h, the finished catalyst cat-4 is obtained, and the active component of the catalyst is K _0.15 Mg _0.85 NiO ₃ .

Comparative example 1

The preparation method of catalyst described in this comparative example comprises the steps:

(1) Weigh 192g of citric acid and add it to 500mL of deionized water for dissolving to obtain a citric acid solution for subsequent use;

(2) Take by weighing 20.2g potassium nitrate, 205.1g magnesium nitrate, 290.7g nickel nitrate and join in 1000mL deionized water to make a solution for subsequent use;

(3) In a stirring state, add the solution obtained in step (2) dropwise to the citric acid solution obtained in step (1), and mix well; then heat the obtained solution to evaporate water, so that it gradually becomes condensed glue;

(4) Put the obtained gel into a drying oven and dry it at 120°C, then put it into an electric furnace and bake it at 750°C for 6 hours to obtain a semi-finished catalyst;

(5) After pulverizing the catalyst semi-finished product obtained by roasting, add 69.1g of calcium aluminate cement, 142.5g of alumina and appropriate amount of water to mix evenly, and press molding, after steam curing for 24 hours, a comparative catalyst cat-5 is obtained, the catalyst The active component is K _0.2 Mg _0.8 NiO ₃ .

Comparative example 2

This comparative example carries out carbon conversion rate, potassium loss ratio comparison with industrial catalyst A, and this catalyst chemical composition NiO% (m/m) >=16, improves the anti-coking performance of catalyst by directly adding kanepheline double salt.

Comparative example 3

The preparation method of hydrocarbon steam reforming catalyst described in this comparative example comprises the steps:

(1) Weigh 192g of citric acid and 142.5g of alumina into 500mL of deionized water, mix well, and set aside;

(2) Weigh 30.3g of potassium nitrate, 179.5g of magnesium nitrate, and 290.7g of nickel nitrate into 1000mL of deionized water, fully mix to form a solution, and set aside;

(3) Under stirring, add the solution in step (2) dropwise to the liquid mixture obtained in step (1), and mix thoroughly; then heat the obtained liquid mixture to evaporate water, so that it gradually becomes a gel ;

(4) Put the formed gel into a drying oven, and after drying at 120°C, continue to put it into an electric furnace for roasting at 750°C for 6 hours to obtain a semi-finished catalyst;

(5) The semi-finished product obtained by the above-mentioned roasting was crushed, and 69.1 g of calcium aluminate cement and appropriate amount of water were added to mix evenly, and then pressed and molded. After steam curing for 24 hours, the comparative catalyst cat-6 was obtained.

The active component of the catalyst is K _0.3 Mg _0.7 NiO ₃ .

Experimental example

In view of the complex characterization of the pressurized activity of hydrocarbon steam reforming catalysts, which is a balance of multiple data indicators, the present invention uses n-hexane as a raw material, selects the carbon conversion rate as a catalyst activity reference index, and is a small pressurized activity evaluation device for catalyst activity evaluation A conventional device in the field is adopted, and the specific structural diagram is shown in Figure 2, and the steps of use are well known to those skilled in the art.

The specific catalyst pressurization activation conditions are:

Catalyst particle size: 40-60 mesh;

Catalyst loading: 45mL;

Pressure: 3.0MPa;

Carbon space velocity: 10000h ^-1 ;

_H2O /C (mol/mol): 2.0;

Bed temperature: inlet temperature 480°C, outlet temperature 700°C;

Running time: 100h;

Carbon conversion rate=(CO content in conversion process gas (%)+CO content in conversion process gas (%))/ _total carbon in conversion process gas (%);

Determination of potassium loss rate: Weigh 40-50 mesh samples quantitatively, immerse in 200mL water, heat and reflux for 6 hours, and measure the potassium content in the water with a flame photometer.

The carbon content in the unloaded sample at the outlet section of the catalyst bed was measured by a carbon-sulfur analyzer.

The evaluation data results of the catalyst are shown in Table 1 below.

Table 1 Evaluation and analysis data after 100 hours of pressure evaluation

As can be seen from the data in Table 1, the carbon conversion rate of the catalyst prepared by the present invention is comparable to that of the industrial catalyst A. After 100h evaluation, the potassium loss rate of the catalyst prepared by the present invention and the carbon content in the unloaded sample are all better than the industrial catalyst A. It shows that the catalyst prepared by the present invention has good anti-coking ability, potassium-fixing ability, and good activity that can be used in industrial production.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (10)

1. A novel hydrocarbon steam reforming catalyst, characterized in that the catalyst comprises the following components in mass content, based on the total amount thereof:

35-45wt% of perovskite type active component;

15-25wt% of calcium aluminate cement;

α-Al ₂ O ₃ the balance;

the perovskite active component has a general formula K _x Mg _1-x NiO ₃ The structure shown, wherein x=0.1-0.2.

2. The novel hydrocarbon steam reforming catalyst of claim 1, wherein the catalyst has a pore volume of 0.30-0.50mL/g, a bulk density of 0.85-0.95Kg/L, and a catalyst side pressure strength of greater than 250N/particle.

3. The novel hydrocarbon steam reforming catalyst of claim 1 or 2, wherein the catalyst comprises a four-hole column, a seven-hole column, a raschig ring, a seven-tendon wheel.

4. A process for preparing the novel hydrocarbon steam reforming catalyst of any one of claims 1 to 3, comprising the steps of:

(1) Taking a selected amount of said alpha-Al ₂ O ₃ Adding citric acid, and adding water, and mixing to form liquid mixture;

(2) Adding potassium nitrate, magnesium nitrate and nickel nitrate according to the proportion of the selected perovskite type active component to prepare a solution for later use;

(3) Dripping the solution obtained in the step (2) into the liquid mixture obtained in the step (1), fully and uniformly mixing and heating to evaporate water so as to gradually change the water into gel;

(4) Drying and roasting the gel obtained in the step (3) to obtain a semi-finished catalyst product for later use;

(5) Pulverizing the obtained catalyst semi-finished product, adding a selected amount of calcium carbonate cement, uniformly mixing, continuously adding water, uniformly mixing, performing compression molding, and curing to obtain the catalyst.

5. The method for preparing a novel hydrocarbon vapor conversion catalyst according to claim 4, wherein the molar ratio of the amount of citric acid added in the step (1) to the total amount of nitrate in the step (2) is 1:2-4.

6. The method for producing a novel hydrocarbon vapor conversion catalyst according to claim 4 or 5, wherein in said step (4), the temperature of said drying step is 80 to 150 ℃.

7. The method for preparing a novel hydrocarbon steam reforming catalyst according to any one of claims 4 to 6, wherein in the step (4), the temperature of the calcination step is 500 to 1000 ℃ and the calcination time is 4 to 8 hours.

8. The method for preparing a novel hydrocarbon steam reforming catalyst according to any one of claims 4 to 7, wherein in the step (5), the curing step is steam curing, and the curing time is 24 to 36 hours.

9. Use of the catalyst of any one of claims 1-3 in a hydrocarbon steam reforming process.

10. The use according to claim 9, wherein the catalyst is suitable for converting carbon space velocity 8000h at a temperature of 430-600 ℃ at the inlet of the converter and 700-850 ℃ at the outlet ^－1 The hydrocarbon steam converting process with water-carbon ratio of 1.2-3.5 and pressure of 2.0-4.0MPa is used in preparing hydrogen or synthetic gas.

Images