CN100438978C - Catalyst for preparing synthesis gas by partial oxidation of natural gas and preparation method thereof - Google Patents

Abstract

The mass percent of a catalyst which is prepared by oxygenating natural gas partly is: nickel oxide 5-20%, oxide additives 5-25%, silicon carbide 55-90%. The preparation method is: allocating water solution or alcohol solution of soluble nickel salt, allocating metal salt water solution or alcohol solution of oxide additives, mixing the soluble nickel salt solution and metal salt solution according to the component of catalyst, dipping silicon carbide in mixing solution after stirring 1-36 hours, pressurizing 12-24 hours under 1-2MPa, filtering solution, drying under 80-150degreeC, roasting 1-6 hours under 400-900 degree C; repeating the step(2)2-10 times until reaching the mass percent component of catalyst requirement. The invention has characteristics of high activity, high stability and long life time.

Description

Catalyst for preparing synthesis gas by partial oxidation of natural gas and preparation method thereof

technical field

The invention belongs to a catalyst and a preparation method thereof, in particular to a new catalyst for preparing synthesis gas by partial oxidation of natural gas and a preparation method thereof.

Background technique

With the increasing consumption of petroleum resources, the new synthetic routes of using natural gas as an alternative energy source to prepare high value-added liquid chemicals and other organic chemicals are highly valued by countries all over the world. my country's natural gas resources are very rich, and its effective development and utilization have very important practical significance for the strategic adjustment of my country's energy structure and sustainable economic development. Partial oxidation of natural gas to synthesis gas is an important intermediate link in the conversion of natural gas, and the research and development of efficient catalysts is the key. At present, the catalysts used for the partial oxidation of natural gas are mainly divided into two categories: noble metal (Rh, Pt) catalysts and nickel-based catalysts. Because nickel-based catalysts have similar performance to noble metal catalysts in terms of reactivity and high-temperature stability, and are cheap, they have more application prospects. Chinese patent (authorized announcement number: CN 1569330A) discloses a catalyst for preparing synthesis gas by partial oxidation of natural gas and a preparation method thereof. It is characterized by taking Ni as the active component, Al ₂ O ₃ as the carrier, and adopting sol-gel in-situ modification technology to introduce Ni ²⁺ and Li ⁺ and La ³⁺ additive metal ions. Literature (Journal of Fuel Chemistry Vol.34No.4) also reported a catalyst for partial oxidation of natural gas to synthesis gas and its preparation method. It is characterized in that the modified Ni/Al ₂ O ₃ catalyst is prepared by introducing the metal oxide MgO by adopting the distribution equal volume impregnation method. However, these catalysts all use oxides as carriers, which have poor thermal conductivity and tend to generate hot spots during the reaction process, resulting in a decrease in catalyst stability. Chinese patent (patent number: ZL200310109658.8) discloses a Ni catalyst supported by SiC with high temperature resistance and good thermal conductivity. Its preparation method is to dissolve soluble metal nickel salt or a mixture of soluble metal nickel salt and rare earth metal salt in distilled water or ethanol solution, then soak high specific surface area silicon carbide in the above solution, and deposit the metal salt on the The surface of silicon carbide is obtained by drying and roasting. However, since the carrier used is powder, the carbon deposition generated during the reaction can easily cause the catalyst to stick into blocks, block the bed, increase the reaction pressure, and even cause the reaction to be forced to stop. At the same time, the interaction between the surface of the silicon carbide carrier and the metal nickel particles is relatively weak, and there are problems such as sintering and easy loss of the active component Ni in the catalytic reaction, resulting in carbon deposition and activity decline of the catalyst.

Contents of the invention

The purpose of the present invention is to use spherical biomorphic silicon carbide (bioSiC) as a carrier and modify the surface of bioSiC, that is, to introduce other components on the surface of silicon carbide to improve the interaction between the surface of the carrier and the active components , in order to solve the problem of Ni/SiC catalyst sticking and plugging the bed in the partial oxidation of methane and the sintering and loss of the active component Ni, and develop a catalyst with high activity and stability for the partial oxidation of natural gas to produce synthesis gas.

The mass percent of catalyst of the present invention consists of:

Nickel oxide: 5-20%

Oxide additives: 5-25%

Silicon carbide: 55-90%

The silicon carbide is spherical porous bioSiC, which is transformed from crop fruits such as millet, rice and soybean. The particle size range is 1-5mm, and the pore size range is 0.001μm-200μm.

The oxide additives include aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, strontium oxide, zirconium oxide, titanium oxide, gallium oxide and the like.

The present invention is achieved in the following ways:

(1) The configuration concentration is 1-30wt% aqueous solution or alcohol solution of soluble nickel salt, and the configuration concentration is 1-30wt% metal salt aqueous solution or alcohol solution of oxide auxiliary agent, wherein the silicon oxide in the oxide auxiliary agent is orthosilicon hexyl ester;

(2) Mix the soluble nickel salt solution with the metal salt solution or ethyl orthosilicate according to the composition of the catalyst to obtain a mixed solution. After stirring for 1-36 hours, immerse the silicon carbide in the mixed solution and pressurize at 1-2Mpa After 12-24 hours, filter the solution, dry at 80-150°C, and bake at 400-900°C for 1-6 hours;

(3) Repeat step (2) for 2-10 times until the required mass percentage composition of the catalyst is reached.

Described soluble nickel salt is nitrate, acetate or sulfate.

The metal salt is nitrate or hydrochloride.

The catalyst evaluation experiment was carried out in a fixed-bed quartz tube reactor, the molar ratio of methane to oxygen was 2:1, and the flow rate was 100ml/min. Among them, at 800°C, the conversion rate of methane is over 90%, and the selectivity of carbon monoxide and hydrogen is over 95%.

The feature of the present invention is to use spherical biomorphic silicon carbide as the carrier, and introduce the oxide promoter into the Ni/bioSiC catalyst to prepare a modified Ni/bioSiC-M _x O _y

Catalyst (M _x O _y stands for oxide promoter). The catalyst of the present invention adopts spherical bioSiC as the carrier, and introduces additives to modify the surface of the carrier, which promotes the dispersion of active components on the surface of the carrier, and strengthens the force with the carrier to improve the carbon deposition resistance of the catalyst. It solves the problem of sintering and easy loss of active components of the catalyst, and has the characteristics of high activity, stability and long life. At the same time, the carrier used also solves the problem of catalyst sticking and bed blockage in the partial oxidation of methane.

Embodiment one:

Weigh 1g nickel nitrate and dissolve it in 10ml distilled water to form a 10wt% nickel nitrate aqueous solution, then weigh 1.2g aluminum nitrate and dissolve it in 10ml distilled water to prepare a 12wt% aluminum nitrate aqueous solution, then mix the two and stir for 5 hours . Weigh 1g of spherical biomorphic silicon carbide with a specific surface area of 15m ² /g and soak it in the mixed solution, put it into a pressure tank and pressurize it at 2Mpa for 24 hours, filter the solution, dry the catalyst at 100°C, and then Roast at 400°C in a furnace for 6 hours, repeat the process of immersion-pressurization-roasting 5 times, and you can get a catalyst for the preparation of synthesis gas by partial oxidation of natural gas with a loading of nickel oxide of 10%, an auxiliary agent of alumina 15%, and a catalyst carrier of 75%. .

The catalyst evaluation experiment was carried out in a fixed-bed quartz tube reactor, the molar ratio of methane to oxygen was 2:1, and the flow rate was 100ml/min. Among them, at 800°C, the conversion rate of methane was 95%, and the selectivity of carbon monoxide was 99%. %, the selectivity of hydrogen is 98%.

Embodiment two:

Take by weighing 0.15g nickel nitrate and be dissolved in 10ml dehydrated alcohol, configure the nickel nitrate alcohol solution of 1.5wt%, then weigh 0.08g aluminum nitrate and dissolve in 5ml distilled water, configure the aluminum nitrate aqueous solution of 1.6wt%, then dilute or mixed and stirred for 20 hours. Weigh 1g of spherical biomorphic silicon carbide with a specific surface area of 20m ² /g and soak it in the mixed solution, put it into a pressure tank and pressurize it at 1Mpa for 12 hours, filter the solution, dry the catalyst at 120°C, and then Roast at 500°C in a furnace for 6 hours, repeat the process of immersion-pressurization-roasting 7 times, and you can get a catalyst for the preparation of synthesis gas by partial oxidation of natural gas with a loading capacity of nickel oxide of 15%, an auxiliary agent of alumina 10%, and a catalyst carrier of 75%. .

The catalyst evaluation experiment was carried out in a fixed-bed quartz tube reactor, the molar ratio of methane to oxygen was 2:1, and the flow rate was 100ml/min. Among them, at 800°C, the conversion rate of methane was 92%, and the selectivity of carbon monoxide was 98%. %, the selectivity of hydrogen is 98%.

Embodiment three:

Weigh 2g of nickel acetate and dissolve it in 10ml of distilled water to form a 20wt% nickel acetate aqueous solution, then weigh 3g of magnesium nitrate and dissolve it in 10ml of absolute ethanol to prepare a 30wt% magnesium nitrate alcohol solution, then mix the two and stir 5 hours. Weigh 3g of spherical biomorphic silicon carbide with a specific surface area of 8m ² /g and soak it in the mixed solution, put it into a pressure tank and pressurize it at 2Mpa for 15 hours, filter the solution, dry the catalyst at 150°C, and then Roasting at 700°C in a Furnace for 3 hours, repeating the process of soaking-pressurizing-roasting 5 times, you can get a catalyst for the preparation of synthesis gas by partial oxidation of natural gas with a loading capacity of nickel oxide of 10%, additive magnesium oxide of 10%, and a catalyst carrier of 80%. .

The catalyst evaluation experiment was carried out in a fixed-bed quartz tube reactor, the molar ratio of methane to oxygen was 2:1, and the flow rate was 100ml/min. Among them, at 800°C, the conversion rate of methane was 94%, and the selectivity of carbon monoxide was 98%. %, the selectivity of hydrogen is 97%.

Embodiment Four

Weigh 1g of nickel acetate and dissolve it in 20ml of distilled water to form a 5wt% aqueous solution of nickel acetate, then weigh 0.5g of magnesium nitrate and dissolve it in 15ml of distilled water to prepare a 3wt% aqueous solution of magnesium nitrate, then mix the two and stir for 20 hours . Weigh 3g of spherical biomorphic silicon carbide with a specific surface area of 25m ² /g and soak it in the mixed solution, put it into a pressure tank and pressurize it at 1.5Mpa for 24 hours, filter the solution, dry the catalyst at 130°C, and then Roasting in a muffle furnace at 600°C for 4 hours, repeating the process of soaking-pressurizing-roasting 6 times, can obtain a catalyst with a loading of 20% nickel oxide, 7% magnesium oxide as an auxiliary agent, and 73% as a catalyst carrier to prepare synthesis gas by partial oxidation of natural gas catalyst.

The catalyst evaluation experiment was carried out in a fixed-bed quartz tube reactor, the molar ratio of methane to oxygen was 2:1, and the flow rate was 100ml/min. Among them, at 800°C, the conversion rate of methane was 93%, and the selectivity of carbon monoxide was 97%. %, the selectivity of hydrogen is 95%.

Embodiment five:

Weigh 0.5g of nickel nitrate and dissolve it in 2ml of absolute ethanol to form a 25wt% nickel nitrate alcohol solution, then weigh 2.3g of zirconium nitrate and dissolve it in 10ml of distilled water to prepare a 23wt% zirconium nitrate aqueous solution, then mix the two , stirred for 24 hours. Weigh 2g of spherical biomorphic silicon carbide with a specific surface area of 10m ² /g and soak it in the mixed solution, put it into a pressure tank and pressurize it at 2Mpa for 10 hours, filter the solution, dry the catalyst at 120°C, and Roast at 900°C in a furnace for 3 hours, repeat the process of immersion-pressurization-roasting twice to obtain a catalyst for the preparation of synthesis gas by partial oxidation of natural gas with a loading capacity of 5% nickel oxide, 20% zirconia as an auxiliary agent, and 75% catalyst carrier .

The catalyst evaluation experiment was carried out in a fixed-bed quartz tube reactor, the molar ratio of methane to oxygen was 2:1, and the flow rate was 100ml/min. Among them, at 800°C, the conversion rate of methane was 91%, and the selectivity of carbon monoxide was 96%. %, the selectivity of hydrogen is 95%.

Embodiment six

Weigh 1g of nickel acetate and dissolve it in 10ml of distilled water to form a 10wt% nickel acetate aqueous solution, then weigh 1.3g of zirconium nitrate and dissolve it in 10ml of absolute ethanol to configure 13wt% of zirconium nitrate alcohol solution, then mix the two, Stir for 18 hours. Weigh 2.6g of spherical biomorphic silicon carbide with a specific surface area of 17m ² /g and soak it in the mixed solution, put it into a pressure tank and pressurize it at 1.7Mpa for 19 hours, filter the solution, dry the catalyst at 110°C, and then Roast at 600°C in a muffle furnace for 5 hours, repeat the process of immersion-pressurization-roasting 4 times, and you can get the partial oxidation of natural gas with 10% nickel oxide loading, 30% additive zirconia, and 60% catalyst carrier to prepare synthesis gas catalyst.

The catalyst evaluation experiment was carried out in a fixed-bed quartz tube reactor, the molar ratio of methane to oxygen was 2:1, and the flow rate was 100ml/min. Among them, at 800°C, the conversion rate of methane was 93%, and the selectivity of carbon monoxide was 97%. %, the selectivity of hydrogen is 98%.

Embodiment seven

Weigh 1.5g of nickel acetate and dissolve it in 10ml of absolute ethanol to form a 15wt% nickel acetate alcohol solution, then weigh 2.3ml of tetraethyl orthosilicate, then mix the two and stir for 24 hours. Weigh 5g of spherical biomorphic silicon carbide with a specific surface area of 17m ² /g and soak it in the mixed solution, put it into a pressure tank and pressurize it at 1.8Mpa for 20 hours, filter the solution, dry the catalyst at 140°C, and then Roasting in a muffle furnace at 500°C for 3 hours, repeating the process of immersion-pressurization-roasting 4 times, can obtain the partial oxidation of natural gas with a loading of nickel oxide of 15%, an auxiliary silicon oxide of 7%, and a catalyst carrier of 78% to prepare synthesis gas. catalyst.

The catalyst evaluation experiment was carried out in a fixed-bed quartz tube reactor, the molar ratio of methane to oxygen was 2:1, and the flow rate was 100ml/min. Among them, at 800°C, the conversion rate of methane was 92%, and the selectivity of carbon monoxide was 96%. %, the selectivity of hydrogen is 97%.

Claims (6)

1. the catalyst of a preparing synthetic gas by partial oxidation of natural gas is characterized in that catalyst quality percentage consists of:

Nickel oxide: 5-20%

Oxides additive: 5-25%

Spherical biological pattern carborundum: 55-90%

2, the catalyst of a kind of preparing synthetic gas by partial oxidation of natural gas as claimed in claim 1 is characterized in that described carborundum is spherical porous, and particle size range is at 1-5mm, and pore diameter range is at 0.001 μ m-200 μ m.

3, the catalyst of a kind of preparing synthetic gas by partial oxidation of natural gas as claimed in claim 1 is characterized in that described oxides additive is aluminium oxide, silica, magnesia, calcium oxide, strontium oxide strontia, zirconia, titanium oxide or gallium oxide.

4, as each described a kind of preparing synthetic gas by partial oxidation of natural gas Preparation of catalysts method of claim 1-3, it is characterized in that comprising the steps:

(1) configuration concentration is the aqueous solution or the alcoholic solution of 1-30wt% soluble nickel salt, and configuration concentration is the aqueous metal salt or the alcoholic solution of 1-30wt% oxides additive, and wherein the silica in the oxides additive is the own ester of positive silicic acid;

(2) pressing the catalyst composition mixes solvable nickel salt solution with metal salt solution or ethyl orthosilicate, get mixed solution, stir after 1-36 hour spherical biological pattern SiC dipping in mixed solution, pressurization is after 12-24 hour under 1-2Mpa, filter out solution, under 80-150 ℃ condition, dry, at 400-900 ℃ of roasting 1-6 hour;

(3) repeat (2) step 2-10 time, form up to the mass percent that reaches the catalyst requirement.

5, a kind of preparing synthetic gas by partial oxidation of natural gas Preparation of catalysts method as claimed in claim 4 is characterized in that described soluble nickel salt is nitrate, acetate or sulfate.

6, a kind of preparing synthetic gas by partial oxidation of natural gas Preparation of catalysts method as claimed in claim 4 is characterized in that described slaine is nitrate or hydrochloride.