JPS62108703A - Preparation of gaseous mixture having optional ratio of hydrogen to carbon monoxide - Google Patents

Abstract

PURPOSE:To obtain gaseous mixture having desired ratio of H2 to CO optionally by using Pd alloy film together with methanol decomposition catalyst and adjusting the H2/CO ratio by changing the amt. of H2 to be withdrawn through the film. CONSTITUTION:A reactor housing a Pd alloy film for permeating H2 together with methanol decomposing catalyst in the inside is used in the process for obtd. gaseous H2 and gaseous CO by cracking methanol vapor catalytically on a catalyst, and the ratio of H2/CO of the gaseous mixture obtd. at one end of the reactor is adjusted optionally by changing the amt. of H2 to be withdrawn through the Pd alloy film. Preferred catalyst to be used is one which produces scarcely dimethyl ether, methane, CO2, etc., as by-products. Suitable reaction temp. is 250-500 deg.C taking influences on the active life of the catalyst and the strength of the catalyst, etc., and the thermal load of the material of the reactor into consideration.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to the production of a mixed gas having an arbitrary hydrogen/carbon monoxide ratio, which is used as a raw material gas for various chemical industries such as C1 chemistry or organic synthetic chemistry. Regarding the manufacturing method.

(Prior Art) When attempting to obtain a mixed gas of Hz-CO as a raw material for various chemical industries, steam reforming of hydrocarbons such as natural gas, butane, or naphtha is used on a large scale. However, in this reaction, the reaction temperature is as high as 600-800℃, and K
, it is sometimes necessary to desulfurize the feedstock to protect catalyst activity. Furthermore, the gas obtained in this way also contains a considerable amount of CO2, and if a mixed gas of only Hz-CO is required, CO2 must be removed from this gas, which complicates the process and at the same time leading to higher costs. Furthermore, it is difficult to adjust the gas composition to a desired H2/Go ratio.

On the other hand, in the case of medium to small-scale operations, it is common to use commercially available Hz and CO packed in cylinders and mix them in the desired proportions. However, this method requires high gas prices, cumbersome handling of cylinders, and poor operability.

On the other hand, recently, N2-C due to the decomposition of methanol has been
The production method of O mixed gas has been in the spotlight. The biggest reason for this is that if methanol f decomposes f, then the following formula CH3
0H-2Hz-1-CO KN2 and CO as shown
The only thing that can be obtained is gas. Other reasons include, firstly, that methanol is now being produced overseas in large quantities and at low cost, creating a stable supply system. Second, methanol is a clean substance;
It can be used as a raw material for decomposition without requiring any operations such as desulfurization.

Thirdly, the decomposition of methanol is 250~s o o ”c
This is possible at a relatively low temperature, which is advantageous in terms of energy.

The N2/CO ratio of the gas obtained by the methanol decomposition reaction will be 2 if the reaction proceeds according to theory. On the other hand, the N2/CO ratio of gases used in c1 chemistry or other chemical reactions is smaller than 2, and is between 1 and 2.
is often in the range. That is, it is desired that the gas actually used has a composition that has a slightly lower hydrogen content than the decomposition composition of methanol.

On the other hand, attempts have already been made to control the N2/C0 ratio by passing hydrogen-containing gas obtained by decomposing methanol through various organic polymer separation membranes. For example, Betroczyk, Vol. 7, No. 1, 1984, p. 24, describes how the KHz/C0 ratio changes when the pressures before and after the permeable membrane are changed using methanol decomposition gas using the module method for cellulose acetate hollow fiber rings. It shows how it changes.

(Problem to be solved by the invention) However, according to this method, it is not possible to reduce the N2/CO ratio without increasing the differential pressure before and after the membrane.
2/CO ratio of gas is N unless the differential pressure is 30 Kf/d or more.
2/CO ratio is not 1.0. This method also requires a gas production system consisting of a methanol decomposer, gas cooling and gas-liquid separation, and a gas production system that extracts a portion of N2 from this cracked gas and converts it into N2/C.
The concentration systems that adjust the zero ratio are each operated in separate systems, and in some cases, gas pressure boosting equipment is required between these two systems to increase hydrogen separation efficiency, making the equipment complex. It is not necessarily a good process. Furthermore, the hydrogen extracted from the separation membrane contains not only N2 but also some of the gases contained in the raw material gas, such as CO1, CO2, and N2, so its N2 purity is only halfway through, and its use is limited. It is of low value.

(Means for solving the problems) The present invention solves the above-mentioned drawbacks and achieves the desired Hz/CO
This method provides a method for freely obtaining the ratio, and when methanol vapor is catalytically decomposed over a catalyst to obtain N2 and CO gas, a reactor containing a catalyst for methanol decomposition and a palladium alloy membrane for hydrogen permeation inside is used. By changing the amount of hydrogen extracted through this palladium alloy membrane, the N2-CO mixed gas obtained from one side of the reactor is
This method adjusts the 2/CO ratio to an arbitrary ratio to produce a mixed gas having an arbitrary hydrogen/carbon monoxide ratio.

The catalyst used in the present invention is methanol co%H
Any catalyst can be used as long as it has decomposition activity to 2, and a wide variety of commonly known catalysts can be used, but catalysts that produce less by-products such as dimethyl ether, methane, and CO2 are preferred. For example, a catalyst containing copper oxide, chromium oxide and manganese oxide (Special Publication No. 54-112
74), a catalyst containing copper, zinc and aluminum (
JP 49-47281), a catalyst containing oxides of copper, zinc, aluminum and thorium (US Pat. No. 4,
No. 091,086), catalysts containing oxides of copper, zinc, aluminum and chromium, and catalysts containing oxides of nickel and aluminum (Japanese Patent Application Laid-Open No. 1983-1989)
56302), and K is a catalyst in which nickel, cobalt, iron, ruthenium, nickel, platinum, or palladium is supported on alumina or titanium oxide (Fuel Road Journal 594O-47 (+980), JP 1986-1
79146, JP-A-60-60902, JP-A-6O-8
Examples include Group Vl catalysts of the periodic table such as 2137).

Regarding the reaction temperature in the present invention, a higher temperature is preferable in order to increase the permeability of hydrogen to the palladium alloy membrane, but considering the effect on the active life of the catalyst, the strength, etc., and the heat burden on the reactor material, etc. A temperature of 150 to 700°C, preferably 250 to 500°C is suitable. In addition, the reaction pressure used in the present invention is preferably as high as possible in order to increase the permeability of hydrogen to the palladium alloy membrane, but considering the strength of the palladium alloy membrane and the impracticality of unnecessary high pressure. , pressure+ooKf/iG or less, preferably 50KIi
/iG or less.

Also, the space velocity of steam is 50-50,00 Ghr.

Preferably it is 100 to 10,000 hr.

The palladium alloy membrane used in the present invention is not particularly limited in its shape, membrane thickness, alloy composition, etc. It is built in a reactor, and a catalyst is present around it, and decomposition occurs on the catalyst. It is sufficient if the structure is such that the hydrogen-containing gas that has passed through the reactor can immediately come into contact with the palladium alloy membrane, and the permeated hydrogen can be led out of the reactor through a pipe or the like.

(Effects of the Invention) According to the present invention, (1) Hz-CO gas generated by decomposition of methanol on the catalyst immediately contacts the palladium alloy membrane, so only Hz can be extracted from the system through the palladium alloy membrane. Therefore, by adjusting the amount of Hz extracted through the palladium alloy membrane, it is possible to obtain a gas with a desired Hz/CO ratio from one side of the reactor.
Since a CO mixed gas is obtained, the entire device becomes compact9, and the equipment is also reduced, which is advantageous in practice.■ Hz/C0U is used because a palladium alloy membrane is used for H2 extraction.
The Hz extracted for Section 4 has all high purity and can be immediately used for semiconductors in the electronic industry.
Since z is extracted from the reaction zone, the reaction tends to proceed in the direction of decomposition of methanol in an equilibrium manner, which has the effect of improving the methanol reaction rate.

(Example) Example 1 A stainless steel reaction tube with an inner diameter of 14 mm and an outer diameter of 411 II+ thermocouple protection tube in the center. Palladium alloy tube (
Made by Nippon Bionics ■, outer diameter, +1.5tntr x
Using a reactor with fixedly built-in +271 m1), 1% pt/carbon catalyst made by Nippon Engel Rud was crushed into 14 to 20 meshes, and +7 m, 6.269 m was packed around the palladium alloy tube. . The reactor was heated by wrapping an aluminum block around the reactor and wrapping a nichrome wire around this.

Using this reactor, reactions were carried out using methanol as a raw material under various conditions at varying temperatures and reaction pressures, and the results shown in Table 1 were obtained.

Example 2 Using the same reactor and catalyst as in Example 1, the reaction pressure was 9.
The amount of purge gas and the H2/Go ratio in the purge gas were investigated by changing the amount of high-purity hydrogen extracted from the palladium alloy tube under the conditions of Kg/cdG and a reactor external temperature of 440°C. The results are shown in Table 2.

Table 2 Patent applicant: Mitsubishi Gas Chemical Co., Ltd. Representative Kazuyoshi Nagano Japan Bionics Co., Ltd. Representative Fumio Takasaki Procedural amendment December 14, 1985

Claims (1)

[Claims] Methanol vapor is catalytically cracked over a catalyst to produce H_2 and C
To obtain O gas, we use a reactor containing a catalyst for methanol decomposition and a palladium alloy membrane for hydrogen permeation inside, and by varying the amount of hydrogen extracted through this palladium alloy membrane, we obtain H_2- from one side of the reactor.
A method for producing a mixed gas having an arbitrary hydrogen/carbon monoxide ratio, characterized by adjusting the H_2/CO ratio of the CO mixed gas to an arbitrary ratio.