JPS5811919B2 - Seizouhouhou - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing fuel gas.

Since crude methanol contains compounds consisting of carbon, hydrogen and oxygen such as methyl formate, dimethyl ether, and alcohols having 2 to 4 carbon atoms, and water, these are usually removed by distillation.

However, since this distillation process requires precise operations and large-scale equipment, the purified methanol obtained is inevitably expensive.

Therefore, the inventor of the present invention conducted various studies aimed at directly using crude methanol as an industrial raw material, and as a result, succeeded in producing fuel gas using this as a raw material, and finally completed the present invention. It is.

That is, the present invention is a method for producing fuel gas characterized by catalytically cracking crude methanol or a crude methanol-water mixture in the presence of a ruthenium-based catalyst.

The present inventor has already developed a technology for producing fuel gas using methanol as a raw material (Japanese Patent Publication No. 57-24834
The present invention is a further development of the prior art.

In the present invention, crude methanol (in the claims of this specification and the detailed description of the invention, crude methanol refers to
Gas for catalytically decomposing crude methanol-water mixture in the presence of a ruthenium-based catalyst. By conducting the reaction by appropriately selecting the reaction temperature and reaction pressure, even when the water vapor/carbon molar ratio is low, carbon precipitation does not substantially occur on the catalyst and other gases are removed. For example, fuel gas equivalent to city gas can be directly produced without any heat adjustment such as mixing.

In this case, the above-mentioned methyl formate, dimethyl ether, alcohols having 2 to 4 carbon atoms, etc. contained in the crude methanol will not have any adverse effect on the catalyst and will be decomposed together with methanol as long as it does not exceed 5% by weight. completely gasified.

Therefore, the production cost of fuel gas is significantly reduced compared to when purified methanol is used as a raw material.

According to the method for producing fuel gas according to the present invention, gas can be supplied in large quantities as city gas in a fixed manner using large-scale equipment, and furthermore, it can be supplied in a semi-fixed manner by satellite bases etc. installed in urban delayed-effect areas. Of course, it is also possible to produce fuel gas continuously and stably using a compact device, so for example, a gas generator that can be mounted on a vehicle can be used to easily and safely produce fuel gas temporarily at any required point. It is also possible to supply fuel gas.

In city gas supply systems using pipelines, supply shortages may occur in some areas in the event of gas leaks or other accidents, or during peak load periods in winter, and it is hoped that some measure will be implemented to deal with this. The fuel gas production method of the present invention can fully meet these demands.

In the present invention, crude methanol or a crude methanol-water mixture is used as the raw material.

The mixing ratio of crude methanol and water as raw materials can be determined as appropriate depending on the combustibility of the target fuel gas, but usually the cell ratio is H2O/CH30H (meaning crude methanol, the same hereinafter) = 0. A range of 4 to 4 is preferable.

Here, H2O/CH30H=0 means that crude methanol is used alone.

However, even if the amount of water is increased too much, the combustibility such as the amount of heat generated and the combustion rate will not change much, but on the contrary, the loss of heat will increase, so preferably the value of H2O/CH3OH is 0 to 0.
A range of 4 is desirable.

In the present invention, ruthenium metal and/or ruthenium oxide is used as a catalyst.

These catalysts are used by being supported on a heat-resistant carrier such as alumina, silica, magnesia, etc. by a conventional method.

The amount of catalyst supported on the carrier is about 0.1 to 5
A range of weight % (in terms of elemental metal) is preferred.

In the catalytic cracking of crude methanol or crude methanol-water mixtures, other metals belonging to Group Ⅰ also show relatively good catalytic activity in the initial stage, but in the long term the catalytic activity decreases due to factors such as carbon precipitation. Since the activity is greatly reduced, in the present invention, a Ru-based catalyst is particularly advantageously used which can effectively suppress carbon deposition and maintain high catalytic activity for a long period of time.

For the catalytic cracking method used in the present invention, a commonly known method may be adopted. For example, crude methanol or a crude methanol-water mixture is heated to steam, raised to the required reaction temperature, and then heated in an adiabatic reactor under an appropriate pressure. This can be carried out by contacting the catalyst with a catalyst.

This reaction is an exothermic reaction, and since the outlet temperature of the reactor and the reaction pressure at that time affect the composition of the gas obtained, it is possible to obtain a gas with the desired gas composition by appropriately selecting the reaction conditions. (CH4, H2, CO,
A mixed gas of CO2°H2O) can be obtained.

The outlet temperature and reaction pressure in the catalytic cracking reaction may be appropriately determined depending on the composition of the fuel gas to be obtained as described above, but usually 400 to 700°C and 2 to 10 kg.
/cm2 (absolute pressure) is preferable.

The gas thus obtained can then be cooled to around room temperature, separated into gas and liquid by an appropriate method, and then supplied as, for example, city gas.

Next, the fuel gas production method of the present invention will be explained in more detail based on the accompanying drawings.

Crude methanol or a crude methanol-water mixture (crude methanol will be explained below as an example) using the equipment shown in the drawing.
When producing fuel gas using methanol as a raw material, crude methanol as a raw material is pumped from tank 1 to lines 10 and 1 by pump 9.
1 and then sent to the heat exchanger 5.

The crude methanol heated in the heat exchanger 5 becomes steam and is sent to the heating furnace 4 via a line 12, and after being raised to an appropriate temperature required for the reaction, it passes through a line 13 to an adiabatic type contactor. It is sent to the decomposition reactor 3.

The reactor 3 is filled with a Ru-based catalyst, and the heated crude methanol comes into contact with the catalyst and is decomposed.

The gas at the outlet of reactor 3 has an equilibrium composition under the reaction conditions (H2
, CH4, CO.

(mixed gas of CO2 and H2O).

The output gas from the reactor 3 is sent to the heat exchanger 5 through a line 14, where it is cooled by exchanging heat with raw material crude methanol, and further cooled from line 15 to a cooler, such as an air fin cooler 6, to approximately room temperature. be done.

The gas is then sent through line 16 to gas-liquid separator 8;
Gas and water are separated, and the gas is sent through line 17 to, for example, a city gas pipe.

The water is discharged through line 18 as waste water or recycled for use.

In addition, a line 31 branched from line 15 to prevent a large temperature difference between the input and output of the reactor due to reaction heat;
The mixed gas at the outlet of the reactor may be recycled to the reactor 3 through the heating furnace 4 via the recycling compressor 30 and line 32.

By appropriately selecting reaction conditions, the gas sent out from the line 17 can be used as city gas without any calorific value adjustment.

The fuel tank 2 contains fuel such as LPG.
It passes through the line 19 and is burned in the burner of the heating furnace 4.

The device shown in the drawings can be compacted and moved by mounting it on a car, and can also temporarily generate fuel gas at any location.

Currently, the price of crude methanol is higher than that of naphtha, butane, and other gas feedstocks, but as demand increases, the price is likely to fall. This is expected to be a particularly useful manufacturing method.

The following Examples 1 to 4 show examples of the present invention. Approximately 1% by weight (in terms of Ru metal amount) is supported on γ-alumina by a conventional method using Ru chloride as a Ru source using the gas production equipment shown in the drawings. Crude methanol or a crude methanol-water mixture is passed over the prepared catalyst.

When the obtained mixed gas is cooled to around room temperature and the drained water is separated, the fuel gas of the present invention is produced.

H2O/CH3OH, reaction conditions, composition of generated gas, etc. are shown in Table 1 below.

Note that the raw material crude methanol contained 23.5% by weight of water and 1.03% by weight of a compound consisting of carbon, hydrogen, and oxygen such as methyl formate, dimethyl ether, and ethanol.

Example 5 A crude methanol-water mixture having the composition shown in Table 2 below was gasified using the apparatus shown in the attached drawing.

As a catalyst, a catalyst (A) in which 2% by weight of Ru was supported on γ-A12O3 was used.

Table 3 shows the reaction conditions, the required amount of catalyst at the beginning of the reaction and after 1000 hours, the amount of carbon deposited, etc.

Furthermore, Table 3 shows that N is added to α-5γ-A12O3 as a catalyst.
i15% by weight supported (B) or α-2γ-A
The results obtained when using 12O3 with 16% by weight of Co supported (C) are also shown.

From the results shown in Table 3, Ru-based catalysts have superior initial activity compared to Ni and Co-based catalysts, which are other metals belonging to group It is clear that excellent catalytic activity is maintained.

[Brief explanation of the drawing]

The drawing is a flow sheet outlining an embodiment of the method of the invention. In the drawing, 1... raw material tank, 2...
... Fuel tank, 31 ... Catalytic cracking reactor, 4.
... Heating furnace, 5 ... Heat exchanger, 6 ...
... Cooler, 8 ... Gas-liquid separator, 30 ...
...Recycling compressor.

Claims (1)

[Claims] 1. A method for producing fuel gas, which comprises catalytically cracking crude methanol or a crude methanol-water mixture in the presence of a ruthenium-based catalyst.