JPH07173088A - Manufacture of methanol from carbon dioxide and hydrogen - Google Patents

Abstract

PURPOSE: To economically convert a mixture consisting of carbon dioxide and hydrogen into methanol in a high yield at a low temperature and under a low pressure by supplying the mixture into a thermal reactor in the presence of a copper catalyst.

CONSTITUTION: A mixture consisting of carbon dioxide and hydrogen is supplied into a reactor at the top of the reactor and subsequently a catalyst based on copper is immersed in the lower zone of the reactor. The dwelling time SV in the catalyst depends on the temperature T in the reactor, the quotient of SV divided by T is in the range of 10-50 and SV is defined as the volume of gas/hr divided by the total gas volume. Concretely, the reaction is carried out employing an H₂/CO₂ mixture in a molar ratio of 1:1 to 10:1 at a dwelling time of 1/10-10 sec, at a pressure of 1-30 bar and a temperature of 140-300°C. And carbon dioxide is obtained by post treatment of exhausts from an energy generating apparatus by combustion of fossil fuels and hydrogen is obtained by decomposition of water or hydrogen sulfide.

COPYRIGHT: (C)1995,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for supplying a mixture of carbon dioxide and hydrogen to a thermal reactor and converting it into methanol while pressurizing in the thermal reactor and in the presence of a catalyst. It relates to a method for producing methanol from hydrogen.

[0002]

2. Description of the Related Art In this case, the present invention is based on the periodical publication "HITA
CH REVIEW ", December 1990, Volume 39, No.
6, pages 318-319, especially FIG. 8 on page 318 or
N. Kanoun et al., CATALYSIS LETTERS 15, (1992)
“Catalytic properties of ne” on pages 231-235.
w Cu based catalysts containing Zr and / or V for me
thanol synthesis from a carbon dioxide and hydroge
It is related to the known art as is clear from "n mixture".

The amount of carbon dioxide released during fossil fuel combustion is
It has caused global changes in the composition of the atmosphere and is capable of causing significant meteorological changes due to the greenhouse effect. 19
Intergovernmental Panel on Climate Change (IPCC-Kom) prepared for the World Meteorological Conference in Geneva in October / November 1990.
According to the report of the mission), in order to stabilize the carbon dioxide content of the atmosphere, the amount of carbon dioxide emission must be immediately reduced by 60%.

[0004] At present, very little use, which requires a higher amount of carbon dioxide and at the same time contributes to the reduction of emissions, eg tertiary petroleum mining (tertiaere Oelfoerderun
g) Only (Enhanced Oil Recovery) exists. Proposed Final Stockpiling Initiative (Endlagerungs
Konzepte (seawater, natural gas fields) are almost unachievable during this century, and may remain closed forever for biological reasons, for example. Alternatively, it is conceivable to convert carbon dioxide into a compound which can be sold in large quantities as a fuel, for example for transportation or combustion equipment. The compound is primarily methanol or methane.

In principle, the synthesis of the substance proceeds by the following total reaction: CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O CO ₂ + 4H ₂ → CH ₄ + 2H ₂ O classical In the case of chemical treatment techniques, the reaction is carried out under special pressure, for example with special catalysts such as rhodium with metal oxides, copper / zinc with chromium, aluminum, manganese, silver or vanadium or copper / nickel compounds. Can be carried out only at a temperature of 230 to 280 ° C.

The publication "HITACH REVIE" mentioned at the beginning
W ", op. Cit., In schematic form, the classical process for the synthetic production of methane and methanol requires two new processes, in which water or hydrogen is
Reacts directly with carbon dioxide.

One method (“photo-electrochemical conversion method (Photo-
In the case of electric chemical conversion) "), water molecules are decomposed by the photocatalyst. Protons (H
⁺ ) Reduces carbon dioxide to methane or methanol. However, the intended efficiency (energy conversion efficiency) in this case is below 1%. Moreover, a very large electrode area would be required.

In another known method, carbon dioxide is catalytically hydrogenated using oxygen generated by solar energy ("hydrogenation"), already carried out by the market during the hydrogenation of carbon monoxide. It is a method. In this case, the high pressure and high temperature required in this case, together with cheap hydrogen preparation, are important issues for economical use.

Finally, it is known from DE-A 4220865 to describe a process for the synthesis of methane or methanol which can already be carried out economically at low temperatures and pressures. In this case, in the reaction chamber,
A mixture of substances containing carbon dioxide and hydrogen is exposed to electrostatic discharge.

In the case of the known catalytic reaction processes, there are only vague statements regarding the pressure and temperature in the reaction chamber, the residence time of the mixture in the catalyst (bed) or the pretreatment of the catalyst. However, the scale agreement of the processes is crucial for the achievable methanol yield.

[0011]

The present invention is subject to the problem of obtaining a process for the production of methanol which is already economically viable at low temperatures and pressures and which achieves high methanol yields. There is.

[0012]

According to the present invention, the above-mentioned object is to supply a mixture of carbon dioxide and hydrogen from above into a reaction chamber, and then to immerse the catalyst in the lower portion of the reaction chamber, A copper-based material is used as the material, and the residence time in the catalyst depends on the temperature in the reaction chamber, and the quotient of the residence time sv and the temperature t is between 10 and 50. It is solved by defining such a degree, in which case the residence time sv is defined as the gas volume / hour divided by the total amount of gas, and the temperature is in degrees Celsius.

When using the above teachings, it is possible for the first time to produce larger quantities of methanol in variable time and thus to almost recycle the greenhouse gas carbon dioxide. In this case, it has proved to be particularly advantageous to use a copper-based catalyst which has been conditioned for several hours beforehand with a mixture of nitrogen and hydrogen.
As a catalyst material, the publication “Catalytic properties of new Cu based catalysts co
ntaining Zr and / or V for methanol synthesis from a
"Carbon dioxide and hydrogen mixture", all the substances described in the above mentioned are applicable, and the catalyst material is usually marketed as a pellet.

The starting material hydrogen can be produced by methods prevailing today, for example by electrolysis,
In this case, the energy source is nuclear energy or renewable energy source (sun, wind, hydropower, biomass)
Can be used. Moreover, hydrogen can be obtained by decomposition of hydrogen sulphide (H ₂ S) using microwaves, electrostatic discharge, pyrolysis or electrolysis. Hydrogen sulphide is mostly produced as industrial waste for certain chemical processes; it is also a by-product of the natural gas processing industry. Furthermore, the acquisition of hydrogen from hydrogen sulfide has the advantage that the binding energy of hydrogen sulfide is smaller than that of water.

CO required for methanol synthesis
₂ occurs as an undesired component during the combustion of fossil fuel energy carriers. Before this kind of carbon dioxide is mixed with hydrogen and then fed to the thermal reactor, it must be separated from another fuel residue. To this end, a number of technologies have already been provided today for preparing carbon dioxide for food use (food use) or chemical use (chemical use) (ABB Lummus Cres).
t, 12141 Wickester, Houston, TX 77079-9570, USA Dateless Newsletter “CO ₂ Recovery from Fl
See ue Gas).

The method according to the invention is explained in greater detail below by means of an embodiment on the basis of the drawing.

[0017]

EXAMPLE In the case of a schematic laboratory structure of a device for the synthesis of methanol (CH ₃ OH), pure hydrogen and pure carbon dioxide are fed via high-pressure regulators 1 and 2, respectively. And supply it to the mixer 3.

The mixer 3 is equipped with a safety valve 4. From this mixer 3, the H ₂ / CO ₂ mixture arrives in a cylindrical reactor 5. A catalyst 6 is gently stacked in the bottom region of the reactor 5. The catalyst reaches about 1/10 of the height of the container in the case of a laboratory structure. This catalyst is commercially available in the form of pellets and used a pre-ground catalyst material having a particle size of 250-500 μm. In this case, the catalyst is based on Cu and
rma Haldor Topsoe A / S, Nymollevej, DK-2800 Lyn
It is sold under the model number MK-101 of gby. The reactor has a heating device 7. The pressure inside the reactor 5 can be adjusted over a wide range by means of a pressure regulator 8 in the middle of a conduit extending from the reactor. The temperature and pressure in the reactor 5 are grasped using the pressure gauge 9 and the thermometer 10.

From the pressure regulator 8 to the heated conduit 11
A branch valve (Mehrwegeventil) is provided (the heating section is shown at 12 and prevents condensation of the methanol generated in the reactor 5).
It leads to 13. The branch valve allows the gas mixture flowing through the conduit 11 to be fed once to the gas chromatograph 14 or the condenser 15. In the gas chromatograph 14, the composition of the gas mixture leaving the reactor 5 can be qualitatively and quantitatively determined. In the condenser 15, the methanol 16 condensed at about 60 ° C. is collected.
The unreacted H ₂ / CO ₂ mixture is released in the field (for this laboratory structure).

The diagram according to FIG. 2 shows the relationship between the methanol conversion rate CR in% and the pressure P inside the reaction chamber 5 at various temperatures. In general, the conversion rate CR increases with increasing pressure. Also, first, the conversion rate CR increases with increasing temperature; this conversion rate reaches a maximum at a value of 220 to 250 ° C. and decreases again with increasing temperature.

To the Applicant's knowledge, two competing processes are useful for the above optimum values: methanol is used in the reactor 5
In, essentially all of the following reactions are formed: CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O (1) Methanol synthesis yields higher conversions at lower temperatures, but after this The process proceeds even more slowly, and the residence time in the catalyst bed must be correspondingly lengthened. In contrast to this, the action of the catalyst is such that the specified maximum processing temperature (310 for model MK-101).
(° C) increases with increasing temperature.

In the case of a laboratory structure, the methanol synthesis uses a H ₂ / CO ₂ mixture with a molar ratio of 1: 1 to 10: 1, a residence time of 1/10 seconds to 10 seconds, 1 to 10 seconds.
It was carried out at a pressure of 30 bar and a temperature of 140-300 ° C. In this case, the optimum yield is a molar ratio of 3: 1, about 1
It occurred at a residence time of seconds, a pressure of 20 bar and a temperature of 240 ° C. The CO ₂ conversion rate (amount of CO ₂ fed vs. amount of converted CO ₂ in% of moles) is about 10%, in which case the selectivity (CO ₂ converted moles vs. C
The amount of H ₃ OH formed in% of the number of moles) was above 50%.

The invention has been described in the above case in relation to a laboratory structure, using a specific catalyst. In the case of a large-scale industrial realization of the process according to the invention, carbon dioxide is produced, for example, from a device such as that described in the introductory publication "CO ₂ Recovery from Flue Gas".

Suitable hydrogen sources are, for example, water-electrolyzers operated by nuclear or solar energy. Further, hydrogen sulfide is also applicable as the hydrogen source.

[Brief description of drawings]

1 is a schematic diagram showing an apparatus for carrying out the method according to the invention for the synthesis of methanol on a laboratory scale.

FIG. 2 is a diagram to demonstrate the effect of temperature and pressure in the thermal reactor on the methanol yield at a given residence time.

[Explanation of symbols]

1, 2 quantity regulator, 3 mixer, 4 safety valve, 5
Thermal reactor, 6 catalyst, 7 heating device, 8 pressure regulator, 9 pressure gauge, 10 thermometer, 11 conduit, 12 conduit heating part, 13 branch valve, 14 gas chromatograph, 15 condenser, 16 methanol

Claims (8)

[Claims] 1. A carbon dioxide which is fed to a thermal reactor (5) with a mixture of carbon dioxide and hydrogen and which is converted into methanol under pressure in the thermal reactor and in the presence of a catalyst (6). In the process for producing methanol from hydrogen, a mixture of carbon dioxide and hydrogen is fed into the thermal reactor (5) from above and then the catalyst is immersed in the lower part of the thermal reactor, in which case the catalyst A copper-based material is used as the material, and the residence time sv in the catalyst depends on the temperature T in the reaction chamber and the quotient of the residence time sv and the temperature T is 10 to 5
It is characterized in that it is between values of 0, in which case the residence time sv is defined as the gas volume / hour divided by the total amount of gas and the temperature is in degrees Celsius. A method for producing methanol from carbon dioxide and hydrogen. 2. The temperature in the reaction chamber (5) is 220 to 250.
The method according to claim 1, which is maintained at a value between 0 ° C. 3. Process according to claim 1 or 2, wherein in the mixture the molar ratio of hydrogen to carbon dioxide has a value of 1 to 10, preferably 3. 4. The pressure in the reaction chamber (5) is 1 to 3 bar,
Preferably it is maintained at a value of 20 bar.
The method according to any one of the above. 5. The residence time of the mixture in the reaction chamber (5) is 0.1 to 10 seconds, preferably 1 second.
The method according to any one of items 1 to 4. 6. The carbon dioxide is obtained by post-treatment of exhaust gas from a fossil fuel combustion energy generator.
The method according to any one of items 1 to 5. 7. The method according to claim 1, wherein hydrogen is obtained by decomposition of water or hydrogen sulfide. 8. The method according to claim 7, wherein hydrogen is obtained by decomposition of hydrogen sulphide using microwaves, electrostatic discharge, pyrolysis and / or electrolysis.