JP2010189350A - Apparatus for converting carbon dioxide to methanol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for converting carbon dioxide to methanol by reducing the carbon dioxide that enables exact, simple and quick measurement of the amount of the methanol converted from the carbon dioxide by determining the amount of the formed methanol using a gas analysis means. <P>SOLUTION: The apparatus for converting carbon dioxide to methanol by reducing the carbon dioxide that measures the amount of the methanol formed from the carbon dioxide by determining the amount of the formed methanol using a gas analysis means includes a flow rate regulating means 1 for carbon dioxide, a flow rate regulating means 2 for a reducing gas, a gas mixer 3 of the carbon dioxide and the reducing gas, a reaction unit 6 equipped with a reaction tube 4 housing a catalyst tube filled with a catalyst and a microwave device 5 to irradiate a microwave to the reaction tube that reduces and converts carbon dioxide contained in a gas introduced into the reaction tube to methanol, a means for measuring temperature in the reaction tube and a means 47 for measuring pressure in the reaction tube. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the present invention, carbon dioxide is reduced and converted into methanol, and the amount of methanol is obtained by gas analysis means, whereby the amount of conversion of carbon dioxide into methanol can be measured accurately, simply and quickly. The present invention relates to an apparatus for converting carbon dioxide into methanol.

  It is known that carbon dioxide discharged into the atmosphere from power plants, factories, automobiles, etc. due to human social activities is the main cause of global warming. Reduction is a major issue in protecting the global environment. In view of such a background, various methods for fixing and removing flue gas from a power plant or the like and carbon dioxide in the atmosphere have been proposed.

  Carbon dioxide immobilization methods are generally classified into three types: biological methods, physical methods, and chemical methods. Biological methods using photosynthesis can be expected to immobilize a considerable amount of carbon dioxide, and are also useful for protecting tropical forests and preventing desertification. Research and development of large-scale and continuous culture and growth of microalgae is underway. However, since the immobilization reaction with microalgae proceeds only with microalgae near the water surface, there is a problem that a large area of water is required to immobilize carbon dioxide with microalgae.

  The physical method is a separation / concentration method using dissolution and adsorption of carbon dioxide in a special medium. For example, carbon dioxide is absorbed into an alkaline solution and separated as a carbonate after the reaction, or carbon dioxide. Research has been conducted on methods for desorption and concentration after carbon is adsorbed on a zeolite medium or the like. However, the method of absorbing by alkali requires a large apparatus, and the adsorption method has a problem that enormous energy is required for adsorption and desorption of carbon dioxide.

  The chemical method includes an electrochemical method and a method utilizing a catalytic reaction. For example, as a reduction of carbon dioxide by an electrochemical method, carbon dioxide in an electrolytic solution is decomposed using a special electrode. A method for producing formic acid, methane, etc. at room temperature is known. However, this method requires a large-scale reaction tank, and a large amount of electrical energy needs to be supplied in order to promote the reaction.

  On the other hand, as a reduction of carbon dioxide using a catalytic reaction, there is known a method of converting carbon dioxide into carbon monoxide, methanol, etc. and using it as a fuel or the like. In comparison, there is a possibility that energy can be reduced. In the reduction of carbon dioxide using a catalytic reaction, a reduction reaction of carbon dioxide using a microwave has been studied in order to further reduce energy required for the reduction reaction (for example, Patent Documents 1 to 3). reference).

  In the methods of Patent Documents 1 to 3, when a mixed gas of carbon dioxide and hydrogen is introduced into a reaction tube filled with a catalyst and irradiated with microwaves, methanol and ethanol are generated even at a low temperature (150 to 250 ° C.). However, since the generated alcohol is collected by introducing it into the impinger and cooling it, it is generated when the flow rate of the mixed gas introduced into the reaction tube is increased or the reaction pressure is increased. It has been found that there are cases where the total amount of alcohol cannot be collected, and there is a problem that the alcohol conversion rate cannot be accurately grasped.

  Therefore, there has been a demand for an apparatus that can accurately measure the influence of the mixing ratio of carbon dioxide and hydrogen, the gas flow rate, the reaction temperature, the reaction pressure, and the like without causing such problems.

JP 2006-169095 A JP 2006-216212 A JP 2008-247778 A

  The present invention has been made in view of the above problems, and by converting carbon dioxide to methanol and obtaining the amount of methanol by gas analysis means, the amount of conversion of carbon dioxide to methanol is accurately determined. Another object of the present invention is to provide an apparatus for converting carbon dioxide into methanol that can be measured easily and quickly.

  In order to achieve the above object, the present invention provides the following apparatus.

(1) In a methanol conversion apparatus for measuring the amount of carbon dioxide converted to methanol by reducing carbon dioxide and converting it to methanol, and determining the amount of methanol by gas analysis means,
A flow rate adjusting means for adjusting the flow rate of carbon dioxide;
A flow rate adjusting means for adjusting the flow rate of the reducing gas;
A gas mixing section for mixing carbon dioxide and a reducing gas;
A reaction tube containing a catalyst-filled tube that can be filled with a catalyst, and a microwave device that irradiates the reaction tube with microwaves. The carbon dioxide contained in the mixed gas introduced into the reaction tube is reduced and converted to methanol. A reaction part;
Temperature measuring means for measuring the temperature in the reaction tube;
A pressure measuring means for measuring the pressure in the reaction tube; and a device for converting carbon dioxide into methanol.
(2) The apparatus for converting carbon dioxide to methanol according to (1), wherein the reaction tube has an inlet and an outlet for a mixed gas at both ends thereof.
(3) The apparatus for converting carbon dioxide into methanol according to (1) or (2), wherein the reducing gas is hydrogen.

  According to the present invention, a mixed gas in which carbon dioxide and a reducing gas are mixed is introduced into the apparatus, carbon dioxide is reduced and converted into methanol using a microwave reaction unit, and the amount of the methanol is measured by gas analysis means. Thus, the conversion amount of carbon dioxide into methanol can be measured easily and quickly. By appropriately changing the type of catalyst, the type of reducing gas, the flow rate of carbon dioxide and reducing gas, the reaction temperature or the reaction pressure, it is possible to evaluate the influencing factors on the methanol conversion.

It is a schematic block diagram which shows the conversion apparatus of the carbon dioxide to methanol of this invention. It is a figure which shows the structure of the reaction part.

  An apparatus for converting carbon dioxide to methanol (hereinafter referred to as an apparatus) according to the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration diagram of the apparatus of the present invention. The apparatus of the present invention includes a flow rate adjusting unit 1 that adjusts the flow rate of carbon dioxide, a flow rate adjusting unit 2 that adjusts the flow rate of reducing gas, a gas mixing unit 3 that mixes carbon dioxide and reducing gas, and a catalyst. Reaction comprising a reaction tube 4 containing a packed catalyst packed tube and a microwave device 5 for irradiating the reaction tube with microwaves, and reducing carbon dioxide contained in the mixed gas introduced into the reaction tube to convert it into methanol The reaction tube 4 includes a temperature measuring means 45 for measuring the temperature in the reaction tube and a pressure measuring means 47 for measuring the pressure in the reaction tube.

  The flow rate adjusting means 1 for adjusting the flow rate of carbon dioxide and the flow rate adjusting means 2 for adjusting the flow rate of the reducing gas are provided for measuring and adjusting the flow rate of each gas. A raw material tank such as a carbon dioxide cylinder is connected to one end of the flow rate adjusting means 1, and a gas mixing unit 3 is connected to the other end. A raw material tank such as a hydrogen cylinder is connected to one end of the flow rate adjusting means 2, and a gas mixing unit 3 is connected to the other end. The gas mixing part 3 is provided in order to mix the gas supplied from each cylinder. In the gas mixing unit 3, since the gas whose flow rate has been adjusted by the flow rate adjusting means 1 and 2 is mixed, each gas can be mixed at a predetermined ratio.

  The reaction unit 6 includes a reaction tube 4 that contains a catalyst-filled tube filled with a catalyst and a microwave device 5 that irradiates the reaction tube with microwaves. In the reaction unit, a conversion reaction of carbon dioxide to methanol occurs. . Carbon dioxide and reducing gas are introduced into the reaction tube 4 from the gas mixing unit 3 through an inlet 41a provided at one end (lower end) of the reaction tube 4, and are included in the mixed gas introduced into the reaction tube. Carbon dioxide is reduced by the microwave energy irradiated from the microwave device 5 and converted into methanol.

  As shown in FIG. 2, the reaction unit 6 uses the space inside the microwave device 5 (the space indicated by the dotted line in the drawing) to make microwave transmission to the microwave device made of glass or heat-resistant resin. By fixing the tube 41, it can be configured simply. The tube 41 accommodates a catalyst-filled tube 42 filled with a catalyst, and a reaction tube 4 is produced by installing a thermocouple, a fiber thermometer, etc. as temperature measuring means 45 in the catalyst-filled tube 42. The In the figure, 46 is a sheath made of ceramic or the like that accommodates a thermocouple or the like. By providing the sheath, a ground fault due to microwaves such as a spark from the thermocouple 45 can be prevented.

  The catalyst filling tube 42 is filled with a catalyst 43. When the catalyst 43 is filled on a glass filter 44 or the like installed in the catalyst filling tube, the catalyst can be fixed. A mixed gas is introduced into the reaction tube filled with the catalyst from the inlet 41a, and the introduced mixed gas is passed through the reaction tube 4 at a constant speed.

  When the mixed gas introduced into the reaction tube passes through the reaction tube, it reacts with a catalyst heated by irradiation with a certain amount of microwaves. At that time, carbon dioxide contained in the mixed gas is reduced by the reducing gas, and at least a part thereof is converted into methanol. The gas after the reaction is sent out from the outlet 41b of the reaction tube. Since the pressure measurement means 47 is provided at the outlet 41b, the pressure in the reaction tube 41 is measured by the pressure measurement means 47.

  When a mixed gas is introduced into a reaction tube, the flow rate of the mixed gas is adjusted with a mass flow controller arranged upstream of the reaction tube and then introduced into the reaction tube, so that the flow rate can be easily adjusted. After adjusting the pressure with a buffer tank arranged upstream, the reaction can be controlled easily by adjusting the flow rate with a mass flow controller.

In the apparatus of the present invention, the mixing ratio of the mixed gas can be set to an appropriate ratio by adjusting the flow rate adjusting means 1 and 2. The space velocity of the mixed gas when passing through the reaction tube is not particularly limited, but can be set in the range of about 600 to 30,000 h- ¹ .

  The reducing gas is generally hydrogen, but may be a hydrocarbon such as methane.

The catalyst is not particularly limited as long as it can proceed the carbon dioxide reduction reaction. A catalyst containing one or more elements of any one of Cu, Zn, Cr, Al, Au, and Zr is an example that can be preferably used. For example, a binary catalyst such as CuO-ZnO, CuO-ZnO-Cr, etc. Examples thereof include ternary catalysts such as ₂ O ₃ , or those in which these catalysts are supported on a carrier such as SiO ₂ , Al ₂ O ₃ , and MgO.

  As the catalyst, those having any shape such as powder, granule and molded product can be used. Among these, molded articles are particularly preferable because there is no fear that the catalyst powder will fall off and the influence of the catalyst on the amount of conversion to methanol can be accurately grasped.

  The reaction temperature for heating the catalyst can be set in the range of about 150 to 300 ° C., but an appropriate temperature may be set depending on the type of catalyst used.

  The output, frequency, and irradiation method of the microwave to be irradiated are not particularly limited, and it is preferable that the microwave is electrically controlled by PID control or the like so that the reaction temperature can be maintained within a predetermined range. The frequency of the microwave is 1 GHz to 300 GHz. Microwave irradiation may be either continuous irradiation or intermittent irradiation, and the irradiation time and irradiation stop time depend on the ratio of carbon dioxide in the mixed gas, gas flow rate, reaction temperature, type of catalyst, etc. Determine as appropriate.

  In the apparatus of the present invention, the gas that has passed through the reaction tube (the gas after the reaction) can be sampled at any time through the sampling port 8 provided on the downstream pipe of the reaction tube. And the amount of methanol conversion can be measured by calculating | requiring the amount of methanol contained in the sampled gas by well-known gas analysis means, such as a gas chromatography.

  In the apparatus of the present invention, methanol gas after reaction is not trapped by an impinger or the like, so there is no risk of trap leakage and measurement accuracy is high. Moreover, since it reacts by 1 pass, it is possible to measure the conversion amount to methanol simply and rapidly.

  Hereinafter, the methanol conversion apparatus of the present invention will be described in detail with reference to the drawings by way of examples.

Example 1
FIG. 1 is a schematic configuration diagram showing a methanol conversion apparatus of the present invention. In FIG. 1, 1 and 2 are mass flow controllers (flow rate adjusting means), 3 is a buffer tank (gas mixing unit) that contains a mixed gas of carbon dioxide and hydrogen, 4 is a reaction tube, 5 is a microwave oscillator, and 6 is It is a reaction part. 7 is a ribbon heater for gas heating, and 8 is a gas sampling port. The reaction tube 4 is provided with a pressure gauge 47. A pressure adjusting valve 48 for fine adjustment of pressure is provided upstream of the reaction tube, and a back pressure valve for maintaining pressure in the reaction system is provided downstream of the reaction tube. It is. Each device is connected by a SUS tube and a Teflon (registered trademark) tube. The material of the connecting part is not particularly limited as long as it is a heat-resistant / pressure-resistant material such as SUS or heat-resistant resin.

  FIG. 2 is an explanatory view showing the reaction tube 4 in an enlarged manner. The reaction tube 4 is composed of a pressure resistant glass tube 41 (inner diameter 32 mm), a glass tube 42 filled with catalyst (inner diameter 23 mm), and a glass filter 44 for filling the catalyst 43, and the catalyst layer has a height of 65 mm and weight. 40 g. 45 is a thermocouple for measuring the temperature of the catalyst packed bed, and 46 is a sheath for installing the thermocouple. However, since the glass filter 44 is used for holding a catalyst, it can be used arbitrarily.

  The mixed gas introduced from the inlet 41a to the reaction tube 4 passes through the reaction tube and is sent out from the outlet 41b. The arrows in FIG. 2 indicate the direction in which the mixed gas flows. As shown in FIG. 2, the reaction occurred in the catalyst layer while the gas introduced from the inlet was rising, and the gas exiting the reaction tube from 41b was heated by the ribbon heater 7 so as not to condense in the middle of the piping. It is exhausted through the pipe. Since the sampling port 8 is provided in the downstream of the ribbon heater 7, the reaction product can be collected from the sampling port at any time during the reaction.

(Test Example 1)
In the methanol conversion apparatus, 40 g of a CuO—ZnO-based catalyst was filled in the catalyst filling pipe 42, and this catalyst reaction pipe was installed in the apparatus. Nitrogen was supplied into the apparatus from a nitrogen cylinder, and the air in the apparatus was discharged.
A mixed gas is prepared at a ratio of carbon dioxide / hydrogen = 25/75 (volume ratio), and the pressure in the reaction tube is adjusted to 0.5 MPa while adjusting the pressure with a regulator (regulating valve) 48 in front of the apparatus. Then, the mixed gas was flowed so that the gas composition before the reaction tube was analyzed and confirmed by gas chromatography.
With the mass flow controllers 1 and 2, the flow rate is set so that the carbon dioxide equivalent flow rate is 0.2 L / min (mixed gas flow rate is 0.8 L / min), and microwaves with a frequency of 2.45 GHz are applied to the reaction tube 4. Then, the temperature was raised to 220 ° C., followed by heating at 220 ° C. for 60 minutes to carry out a carbon dioxide reduction reaction.
During the heating for 60 minutes, 0.2 ml of the gas after the reaction was sampled from the sampling port 8 three times, and the gas composition (vol% of methanol) was analyzed and identified / quantified by gas chromatography. The methanol conversion amount was determined from the average value of the analysis results of the collected gas.
The methanol conversion rate (%) is a value obtained by dividing the number of moles of methanol by the number of moles of carbon dioxide in the mixed gas before the reaction.

(Test Example 2)
A mixed gas was prepared at a ratio of carbon dioxide / hydrogen = 20/80 (volume ratio), and the flow rate was set so that the flow rate converted to carbon dioxide was 0.2 L / min (mixed gas flow rate was 1.0 L / min). As in Test Example 1, a carbon dioxide reduction reaction was performed.

(Test Example 3)
A mixed gas was prepared at a ratio of carbon dioxide / hydrogen = 15/85 (volume ratio), and the flow rate was set so that the flow rate converted to carbon dioxide was 0.2 L / min (mixed gas flow rate was 1.4 L / min). As in Test Example 1, a carbon dioxide reduction reaction was performed.

(Test Example 4)
A mixed gas was prepared at a ratio of carbon dioxide / hydrogen = 10/90 (volume ratio), and the flow rate was set so that the flow rate converted to carbon dioxide was 0.2 L / min (mixed gas flow rate was 2.0 L / min). As in Test Example 1, a carbon dioxide reduction reaction was performed.

(Test Example 5)
A mixed gas was prepared at a ratio of carbon dioxide / hydrogen = 5/95 (volume ratio), and the flow rate was set so that the flow rate converted to carbon dioxide was 0.2 L / min (mixed gas flow rate was 4.0 L / min). As in Test Example 1, a carbon dioxide reduction reaction was performed.

  Table 1 shows the experimental conditions and experimental results of Test Examples 1 to 5.

(Test Example 6)
Using 19.4 g of a CuO—ZnO—LaO-based catalyst (Cu: Zn: La = 70: 29: 1) as a catalyst, a mixed gas was prepared at a ratio of carbon dioxide / hydrogen = 10/90 (volume ratio), and the reaction temperature The reduction of carbon dioxide was the same as in Test Example 1 except that the reaction pressure was set to 185 ° C., the reaction pressure was 0.4 MPa, and the flow rate was set to a carbon dioxide equivalent flow rate of 0.4 L / min (mixed gas flow rate was 4.0 L / min). Reaction was performed.

(Test Example 7)
The reduction reaction of carbon dioxide was performed in the same manner as in Test Example 6 except that the reaction pressure was set to 0.6 MPa.

(Test Example 8)
The reduction reaction of carbon dioxide was performed in the same manner as in Test Example 6 except that the reaction pressure was set to 0.8 MPa.

  Table 2 shows the experimental conditions and experimental results of Test Examples 6-8.

  As a result, from Test Examples 1 to 6, it was found that the methanol conversion rate tends to increase by increasing the ratio of hydrogen in the mixed gas of carbon dioxide and hydrogen. From Test Examples 6 to 8, it was found that the methanol conversion rate tends to increase by increasing the reaction pressure.

  The above embodiment shows an example of the apparatus for converting carbon dioxide to methanol according to the present invention, and the present invention is not limited to the above embodiment, but within the scope of the invention described in the claims. It goes without saying that various modifications are possible and are included in the scope of the present invention.

  According to the apparatus for converting carbon dioxide to methanol of the present invention, since it is possible to easily and quickly select a catalyst, reaction conditions and the like in the reduction reaction of carbon dioxide, as a reduction and effective utilization measure of carbon dioxide, It greatly helps to protect the global environment.

DESCRIPTION OF SYMBOLS 1 Carbon dioxide flow rate adjustment means 2 Reducing gas flow rate adjustment means 3 Gas mixing part 4 Reaction tube 41 Microwave-permeable tube 42 Catalyst filling tube 43 Catalyst 44 Glass filter 45 Temperature measurement means 46 Sheath 47 Pressure measurement means 48 Regulator 5 Microwave device 6 Reaction unit 7 Ribbon heater 8 Sampling port

Claims (3)

In a methanol conversion apparatus for measuring the amount of conversion of carbon dioxide to methanol by reducing carbon dioxide and converting it to methanol, and determining the amount of methanol by gas analysis means,
A flow rate adjusting means for adjusting the flow rate of carbon dioxide;
A flow rate adjusting means for adjusting the flow rate of the reducing gas;
A gas mixing section for mixing carbon dioxide and a reducing gas;
A reaction tube containing a catalyst-filled tube that can be filled with a catalyst, and a microwave device that irradiates the reaction tube with microwaves. The carbon dioxide contained in the mixed gas introduced into the reaction tube is reduced and converted to methanol. A reaction part;
Temperature measuring means for measuring the temperature in the reaction tube;
A pressure measuring means for measuring the pressure in the reaction tube; and a device for converting carbon dioxide into methanol.   The apparatus for converting carbon dioxide to methanol according to claim 1, wherein the reaction tube has an inlet and an outlet for a mixed gas at both ends thereof. The apparatus for converting carbon dioxide into methanol according to claim 1 or 2, wherein the reducing gas is hydrogen.

Images