JPH0496995A - Method for producing high calorie gas - Google Patents

Abstract

PURPOSE:To easily obtain the title gas through such processes that O2 is added to a mixture of coke oven gas and converter gas, and the sulfur compounds contained are removed using an iron oxide catalyst, and then the CO and CO2 are hydrogenated in the presence of a catalyst containing Al, Si, etc., followed by acting a methanating catalyst on the system and then removing the inert gas. CONSTITUTION:Oxygen gas 7 is added to a mixture of coke oven gas 1 and converter gas 4, the resulting gas is fed to a gas purifier 6 where the sulfur compounds in the mixed gas are removed in the presence of an iron oxide-based catalyst 9, and the resultant gas is fed to a hydrocarbon-synthesizing equipment 11 where the remaining carbon monoxide and carbon dioxide in the mixed gas is hydrogenated into a hydrocarbon gas in the presence of a complex catalyst 12 consisting of a mixture of (A) a metal (compound) having hydrogenation-catalytic activity and (B) a crystalline aluminosilicate with the molar ratio of the silica to alumina being <=10. Thence, methane gas is produced through a methanating catalyst located on the downstream side of said complex catalyst, and the resultant gas is then passed through a carbon dioxide separator 15 and a nitrogen separator 16 successively to carry out membrane separation of the carbon dioxide in the gas produced, followed by removing the present nitrogen gas through cryogenic separation, thus obtaining the objective high-BTU gas.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing high calorie gas.

[Conventional technology]

Currently, the proportion of liquefied natural gas in city gas raw materials is 70%.
% or more. For this reason, demand for low-calorie gas such as coke oven gas, which has traditionally been the mainstream raw material for city gas, is decreasing more and more.

In order to utilize low-calorie gas as a raw material for city gas, it is necessary to reform it into a gas that has the same calorific value as natural gas.

The following methods are known for producing high-calorie gas comparable to natural gas from coke oven gas, etc., which is produced as a by-product in steel plants.

That is, coke oven gas is hydrodesulfurized in the presence of a Co-Mo catalyst to remove sulfur compounds, and then C
Method I of methanating in a single or multi-stage reactor filled with nickel catalyst etc. by adding O2 (JP-A-56-4
No. 5986), or after hydrodesulfurizing a raw material gas obtained by adding coke oven gas to coke oven gas, in the presence of a catalyst consisting of iron group metals such as cobalt and platinum group metals such as manganese oxide and ruthenium. Reacting carbon monoxide and hydrogen in the raw material gas to produce hydrocarbons having 1 to 4 carbon atoms,
Next, this is introduced into a pressure swing absorption (PSA) device filled with a zeolite-based adsorbent to remove CO2 from the gas, and then introduced into a PSA device filled with an adsorbent such as activated carbon. Method (1) of obtaining high-calorie gas by removing non-flammable components such as nitrogen and hydrogen and low-calorie components (Japanese Patent Application Laid-Open No. 64-56788) is known.

[Problem to be solved by the invention]

However, both methods employ hydrodesulfurization to purify the raw material gas. Therefore, the equipment becomes complicated, the equipment cost becomes high, and an expensive hydrogenation catalyst is required.

Further, in method (2), carbon dioxide supplied from the outside is reacted with hydrogen in coke oven gas to generate methane. This increases the methane concentration in the gas and increases the calorific value. However, in this case, the calorific value of the produced gas is about 8300 kcal/Nm3, which does not meet city gas standards 12A and 13A.

In addition, method
In other words, those with a relatively high content of hydrocarbons having 2 to 4 carbon atoms are targeted, and as they are, they do not comply with city gas standard 13A. Therefore, it is necessary to increase the calorific value by adding a heat increasing agent such as butane gas.

The present invention has been made in view of this point, and has a calorific value that complies with city gas standard 13A without requiring the addition of any heat enhancer using only a mixed gas of coke oven gas and converter gas. The present invention provides a method for producing high calorie gas.

[Means to solve the problem]

The present invention includes a step of adding oxygen to a mixed gas of coke oven gas and converter gas, a step of removing sulfur compounds from the mixed gas in the presence of an iron oxide catalyst, and a step of adding oxygen to a mixed gas of coke oven gas and converter gas. Alternatively, a desired amount of carbon monoxide and carbon dioxide in the mixed gas is reacted with hydrogen in the presence of a composite catalyst consisting of a mixture of a metal compound and a crystalline aluminosilicate having a silica to alumina molar ratio of 10 or less to carbonize. a step of obtaining hydrogen gas; a step of reacting residual carbon monoxide and carbon dioxide in the mixed gas with hydrogen in the presence of a methanation catalyst provided downstream of the composite catalyst to obtain methane gas; A step of removing carbon dioxide gas contained in the generated gas containing hydrogen gas and the methane gas by membrane separation, and a step of removing nitrogen gas contained in the generated gas by cryogenic separation. This is a unique method for producing high-calorie gas.

[For production]

According to the method for producing a high-calorie gas of the present invention, a composite catalyst consisting of a mixture of a metal or a metal compound having hydrogenation catalyst activity and a crystalline aluminosilicate having a silica to alumina molar ratio of 10 or less, and a composite catalyst downstream thereof are provided. Carbon monoxide and carbon dioxide in the mixed gas are reacted separately with hydrogen using the methanation catalyst prepared. Thereby, hydrocarbons each having 2 to 5 carbon atoms and methane gas can be synthesized separately.

Therefore, the ratio of hydrocarbon having 2 to 5 carbon atoms and methane gas in the generated gas can be adjusted as desired.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of a high-calorie gas manufacturing apparatus to which the high-calorie gas manufacturing method of the present invention is applied. This device produces high-calorie gas as follows.

First, the coke oven gas supplied from the coke oven gas supply line 1 is cooled by the precooler 2. Then,
Dust, tar mist, etc. in the cooled coke oven gas are removed by two filters 3 connected to the supply line 1. The filter 3 is composed of, for example, a filter cloth filter, a packed bed filter, or the like.

The coke oven gas purified in this way is mixed with converter gas supplied from a converter (not shown) via the converter gas supply line 4 to obtain raw material gas.

The mixing ratio of coke oven gas and converter gas is 0.5, which is the ratio of (H2CO2)/(CO + CO2) in the raw material gas after mixing.
-10, preferably 1-4. The raw material gas adjusted in this way is mixed with the raw material gas discharged from the gas purification device 6 and the G/G heat exchanger 5, as described later.
to exchange heat.

Next, the source gas is mixed with oxygen supplied from the source gas oxygen supply line 7 via the compressor 8 . The oxygen concentration to be mixed is 0.5 to 3% by volume. Next, the raw material gas mixed with oxygen is introduced into the gas purification device 6. Sulfur oxides in the raw material gas are removed by bringing the introduced raw material gas into contact with an iron oxide catalyst 9 filled in the gas purification device 6 .

Here, as the iron oxide catalyst 9, α
-Fe20. Ultrafine iron oxide and zinc oxide (Z
nO) and copper oxide (CuO), Cab,,S
i02A (1203Mg0sT102, etc., alone or in an appropriate mixture is supported on a carrier, and basic compounds such as alkali metal and/or alkaline earth metal oxides and/or carbonates are added to these. Catalyst) The composition is 30-80% by weight of iron oxide, 2-15% by weight of zinc oxide, 2-15% by weight of copper oxide, and 10% by weight of carrier.
~30% by weight and 1-10% by weight of basic compounds are suitable. Such sulfur oxide removal treatment can be carried out by using, for example, 65% by weight of iron oxide, 5% by weight of zinc oxide, 5% by weight of copper oxide, 20% by weight of carrier, and 5% by weight of calcium oxide as a catalyst. Internal temperature 120~300℃, catalyst bed pressure 1~50kg/cdG, catalyst per unit time
This can be carried out efficiently under conditions of a gas supply rate (space velocity) of 100 to 1000 h-' per unit volume.

Next, after heat exchanged with the raw material gas before purification, the purified raw material gas is introduced into the compressor 10 through the G/G heat exchanger 5, and the pressure is increased to a predetermined pressure. Next, this is introduced into the hydrocarbon synthesis apparatus 11 and reacted with the composite catalyst 12 and the methanation catalyst 13 filled inside the hydrocarbon synthesis apparatus 11 in order. Here, the composite catalyst 12 was developed by the present inventors as a hydrogenation catalyst for carbon dioxide (Japanese Unexamined Patent Publication No. 1-1999)
Publication No. 0638). That is, the composite catalyst comprises a mixture of a metal or metal compound with hydrogenation catalytic activity capable of hydrogenating carbon oxide and carbon dioxide, and a crystalline aluminosilicate having a silica to alumina molar ratio of 10 or less. be.

Metals with hydrogenation catalytic activity include copper, zinc, chromium, molybdenum, tungsten, iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium,
Metals such as platinum can be mentioned. In addition, examples of metal compounds with hydrogenation catalytic activity include oxides of the above metals,
Mention may be made of carbides, nitrides and sulfides. Note that these metals and metal compounds can be used alone or in combination of two or more. Among these, oxides of copper, zinc, and chromium are particularly preferred.

Further, these metals and metal compounds can be prepared in the same manner as in the preparation method of general metal catalysts or metal compound catalysts.

On the other hand, as the crystalline aluminosilicate, which is another component, zeolites such as X-type, Y-type, L-type, mordenite, etc. can be used. The molar ratio of silica to alumina in the crystalline aluminosilicate is set to 10 or less. That is, use Example EVA, A1203 (7) 10x-E le <7) S i 02. Usually, silica is used in an amount of 3 to 10 times the molar amount of alumina. In particular, some of the aluminum in the Y-type zeolite is removed to increase the silica to alumina ratio from 4 to 1 o in terms of molar ratio.
A dealuminated Y-type zeolite is preferred. These zeolites are used as H type, metal ion type, and ammonium type cations. As the metal ion, it is preferable to use ions of metals, alkaline earth metals, earth metals, etc., which have the above-mentioned hydrogenation catalyst activity. Such crystalline aluminosilicate can also be produced according to known methods. For example, if necessary, zeolite may be ion-exchanged to form a predetermined ion type, and then this may be finished by firing.

Composite catalyst] 2 can further contain other components. For example, a metal or metal compound having hydrogenation catalytic activity and another metal compound may be used in combination. Such other metal compounds have, for example, a cocatalytic effect, and specific examples include compounds of alkali metals, alkaline earth metals, earth metals, rare earths, and the like. Furthermore, existing catalysts such as methanol synthesis catalysts and mixed alcohol synthesis catalysts may be included in the composite catalyst.

The content of these other metal compounds and alcohol synthesis catalyst is less than 50% by weight.

The two components can be mixed by pulverizing them and then compression molding them into pellets, by pelletizing each component and then mixing them, or by ion-exchanging the metal or metal compound into crystalline aluminosilicate. Alternatively, any method such as impregnating and supporting may be used. The mixing ratio of both components is not particularly limited and may be appropriately selected depending on the type of each component, reaction conditions, etc. Usually 1:1 to 2 in weight ratio
The ratio is about 0:1, preferably about 1:1 to 10°1, and an excess of crystalline aluminosilicate is more effective.

Furthermore, any known methanation catalyst can be used as the methanation catalyst 13. For example, the methanation catalyst 13 may include a catalyst in which a metal such as ruthenium, rhodium, iridium, nickel, cobalt, or iron is supported on a carrier such as alumina, silica/alumina, silica, or tatinia.

Note that the ratio of the composite catalyst 12 and the methanation catalyst 13 varies depending on the composition of the raw material gas, the type of catalyst used, etc., but usually 0.1 to 1 part by weight of the methanation catalyst is appropriate for 1 part by weight of the composite catalyst. .

Therefore, hydrocarbon synthesis is carried out at a pressure of 5 to 100 kg/cd.
G, reaction temperature 200-450°C, preferably 250-4
The reaction is carried out at a temperature of 00° C. and a space velocity of 100 to 5000 h, preferably 200 to 2000 h.

Next, the hydrocarbonized product gas is guided from the hydrocarbon synthesis device 11 to the aftercooler 14 and cooled while maintaining the pressure during the reaction. Then, the cooled generated gas is
The generated gas is supplied to a carbon dioxide gas separation and removal device 15, and carbon dioxide gas in the generated gas is separated by a membrane.

As the material of the membrane used for this membrane separation, for example, cellulose acetate, polyamide, polysulfone, etc. can be employed.

Next, the produced gas from which carbon dioxide gas has been separated and removed is supplied to the nitrogen separation and removal device 16, where nitrogen in the produced gas is separated by deep cooling. That is, the generated gas is cooled to a temperature at which nitrogen in the generated gas does not liquefy and hydrocarbons from methane to pentane liquefy. Through this cooling process, nitrogen is separated and removed as a non-condensable gas. Next, the condensed hydrocarbons are returned to room temperature and recovered as hydrocarbon gas from the hydrocarbon gas discharge line 17.

The hydrocarbon gas obtained in this way is 1,2000
It has a calorific value of about kcal/Nm'.

Therefore, we diluted this with air and adjusted the heat to 11,000k.
cal/Nm3, and it is possible to obtain high calorie gas that complies with city gas standard 13A.

According to such a method for producing high-calorie gas, a predetermined amount of oxygen is added to the raw material gas supplied to the gas purification device 6. As a result, oxygen reacts with hydrogen and carbon oxide in the raw material gas to promote heat generation, and the temperature of the catalyst layer can be maintained within an appropriate range. Further, the iron oxide catalyst used here has the effect of accelerating the reaction between the organic sulfur compound in the raw material gas and hydrogen or the water produced in the above-mentioned oxidation reaction, as well as capturing the produced hydrogen sulfide. The catalyst, which has captured hydrogen sulfide and turned into iron sulfide, can be regenerated into iron oxide by treating it with a small amount of air and steam, allowing continuous use for long periods of time.

Moreover, the composite catalyst 12 disposed inside the hydrocarbon synthesis apparatus 11 contributes to the combination of alcohol synthesis reaction and alcohol conversion reaction. Therefore, it is not subject to thermodynamic equilibrium constraints, as is the case with hydrogenation reactions of carbon monoxide and carbon dioxide in alcohol synthesis reactions, for example. Therefore, hydrocarbons can be produced in high yields that exceed the thermodynamic equilibrium values for alcohol synthesis. In addition, by using crystalline aluminosilicate with a molar ratio of silica to alumina of 10 or less, the number of carbon atoms can be reduced to 2.
~5 saturated hydrocarbons can be produced with high selectivity. Furthermore, when synthesizing hydrocarbons from -carbon oxide and carbon dioxide, there is no need for a step of converting -carbon oxide and carbon dioxide into alcohol. Therefore, a saturated hydrocarbon having 2 to 5 carbon atoms can be synthesized from carbon monoxide and carbon dioxide in the second stage.

On the other hand, the composite catalyst 1 inside the hydrocarbon synthesis device 11
2 and the methanation catalyst 13 are arranged such that the composite catalyst 12 and the methanation catalyst 13 are sequentially arranged from the upstream side. As a result, the composite catalyst 12 can synthesize saturated hydrocarbons having 2 to 5 carbon atoms, and the methanation catalyst 13 can separately synthesize methane gas.

Therefore, the calorific value of the produced gas can be easily adjusted by arbitrarily adjusting the ratio of methane and hydrocarbons having 2 to 5 carbon atoms in the produced gas. In addition, when the arrangement of the composite catalyst 12 and the methanation catalyst 13 is reversed, the yield of hydrocarbons having 2 to 5 carbon atoms decreases, and a high calorie cannot be achieved.

Additionally, membrane separation is used to separate and remove carbon dioxide gas. Therefore, the gas pressure during hydrocarbon synthesis can be used as is. As a result, carbon dioxide gas can be separated and removed with high efficiency.

In addition, the cryogenic separation method was adopted to separate and remove nitrogen.
2 between the boiling point of nitrogen and the boiling points of other components in the gas
This is because since there is a difference of 0° C. or more, the temperature range during the separation operation can be widened, and the efficiency of separation can be increased.

Examples of experiments conducted to confirm the effects of the present invention will be described below. In this experimental example, a high calorie gas production apparatus shown in FIG. 1 was used.

(1) Preparation of catalyst (a) Preparation of iron oxide catalyst The iron oxide catalyst 9 to be filled into the gas purification device 6 was prepared as follows. In other words, waste acid (F e C1l 2
20-30%) at 700-800°C,
A Fe2O3 powder with a particle size of 60 μm or less was obtained. In addition, ZnO.

CuO was added in an amount of 7.5% by weight and mixed uniformly.

Furthermore, cement (Ca064% by weight, SiO2
22% by weight, AN2035% by weight, etc.) 30% by weight and Ca
After adding 0.07.5% by weight and 20% by weight of water and kneading them uniformly, the mixture was granulated to a particle size of 7 to 15 mm. This granulated product was fired in air at a temperature of about 100 to 400° C. for 1 hour to obtain an iron oxide catalyst 9.

(b) Preparation of Composite Catalyst 12 First, among the composite catalyst 12, a copper oxide-zinc oxide-alumina catalyst was prepared as a metal or metal compound having hydrogenation catalytic activity as follows. Copper nitrate (Cu(NOi)
2”3H20) 10.9kg, zinc nitrate (Z n
(NO3) 2 ・6Hx・0)69.1kg and
Aluminum nitrate (A, Q (NO3)3 ・9H2
0) An aqueous solution of 55.1kg dissolved in about 30ON of water and 90kg of sodium carbonate (Na2 CO3) dissolved in about 30ON of water.
About 1 g of an aqueous solution dissolved in water kept at about 90°C
m3 in a stainless steel container with a pH of 7.0±0.
The mixture was added dropwise while adjusting the temperature to maintain a temperature of 5.

After the dropwise addition was completed, the precipitate formed was filtered, washed, and incubated at 120°C for 2 hours.
After drying for 4 hours, it was calcined in air at 350°C for 5 hours to obtain the desired catalyst. The composition of this catalyst is 61% by weight C
uO-32% by weight ZnO-7% by weight Aρ203.

Moreover, the other crystalline aluminosilicate catalyst of the composite catalyst 12 was prepared as follows.

Dealuminated H-Y type zeolite (trade name of Tosoh Co., Ltd., T S Z 330 HUD, S i 0
2/A, Q 203-5.9) was ion-exchanged for 24 hours at room temperature using an aqueous ammonium nitrate solution at pH 3.0. After that, it was dried at 120°C for 24 hours,
Further, the mixture was calcined in air at 500° C. for 6 hours to obtain a crystalline aluminosilicate catalyst.

The copper oxide-zinc oxide-alumina catalyst and the crystalline aluminosilicate catalyst prepared as above were mixed in a weight ratio of 1=
The desired double metal catalyst 12 was obtained by uniformly mixing the two metals at a ratio of 4 to 4.

(c) Preparation of methanation catalyst Methanation catalyst 13 was prepared in the following manner.

First, add nickel nitrate (N i (NO3) 2.6 H20) 59.5 to about 120 g of water.
After dissolving 48 kg of alumina (Dia Catalyst Co., Ltd., trade name: DC2282), it was evaporated to dryness. Next, this was dried at 120°C for 24 hours, and then fired in air at 500°C for 4 hours.

Further, the target methanation catalyst 13 was obtained by heat treatment for 3 hours in a hydrogen stream at 400°C. The composition of the obtained methanation catalyst] 3 was 20% by weight N, 1-80% by weight A (1203).

(2) Production of high-calorie gas A raw material gas was obtained by mixing coke oven gas and converter gas having the compositions shown in Table 1 below so that the amounts were 80% by volume and 20% by volume, respectively. Furthermore, oxygen is added to this raw material gas so that the oxygen concentration becomes 2% by volume.

Next, the raw material gas to which oxygen had been added was introduced into the gas purification device 6 at a rate of 18 Nm3/h. As the iron oxide catalyst 9, 40 kg of the iron oxide catalyst prepared in (a) above was used. The temperature of the iron oxide catalyst 9 was set to 200° C. at its center to remove sulfur oxides from the raw material gas.

Next, the raw material gas at 300°C discharged from the gas purification device 6 is lowered in temperature to 140°C by the G/G heat exchanger 5, and further reduced to 50 kg/cd by the compressor 10.
Pressure increased to G. Next, this is transferred to the hydrocarbon synthesis equipment 11.
supplied. In the hydrocarbon synthesis apparatus 11, the above (b)
15 kg of the composite catalyst prepared in step (c) and 3 kg of the methanation catalyst prepared in step (c) above were placed in order from the top of the apparatus. The temperature of these catalysts 12 and 13 was set at 300° C., and carbon dioxide and carbon monoxide in the raw material gas were converted into hydrocarbons to obtain a product gas.

Next, the generated gas obtained in this way was 50 kg/c+
While maintaining the pressure of tG, it was cooled to room temperature using the aftercooler 14. Next, this was introduced into a carbon dioxide gas separation device 15 using a cellulose acetate membrane, and carbon dioxide gas in the generated gas was removed by membrane separation. Furthermore, this generated gas was introduced into the nitrogen separation device 16, and nitrogen was separated and removed by a cryogenic separation operation to obtain a hydrocarbon gas.

The composition and calorific value of the gas in each process explained above are as follows:
The results were as listed in Table 1.

The hydrocarbon gas obtained in this way is 12,000k
It had a calorific value of cal/Nm3.

Dilute this with air and get 11000kcal/Nm3
It was confirmed that by doing so, it was possible to easily obtain high-calorie gas that complied with city gas standard 13A.

〔Effect of the invention〕

As explained above, according to the method for producing high-calorie gas of the present invention, there is no need to add any heat enhancer to the mixed gas of coke oven gas and converter gas, and moreover, according to the city gas standard 1.
This method has remarkable effects such as being able to easily produce a high-calorie gas having a calorific value meeting A.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a high-calorie gas production apparatus used in the high-calorie gas production method according to the present invention. DESCRIPTION OF SYMBOLS 1... Coke oven gas supply line, 2... Precooler 3... Filter 4... Converter gas supply line, 5... G/G heat exchanger, 6... Gas purification device, 7... Oxygen supply line, 8... Compressor 9... Iron oxide catalyst, 10... Compressor 11... Hydrocarbon synthesis device, 12... Composite catalyst, 1
3... Methanation catalyst, 14... Aftercooler 1
5... Carbon dioxide gas separation device, 16... Nitrogen separation device,
7. Hydrocarbon gas discharge line.

Claims (1)

[Claims] A step of adding oxygen to a mixed gas of coke oven gas and converter gas, a step of removing sulfur compounds from the mixed gas in the presence of an iron oxide catalyst, and a metal or metal compound having hydrogenation catalyst activity. Hydrocarbon gas is obtained by reacting a desired amount of carbon monoxide and carbon dioxide in the mixed gas with hydrogen in the presence of a composite catalyst consisting of a mixture of silica and alumina with a crystalline aluminosilicate having a molar ratio of 10 or less. a step of reacting residual carbon monoxide and carbon dioxide in the mixed gas with hydrogen in the presence of a methanation catalyst provided downstream of the composite catalyst to obtain methane gas; A method for producing a high-quality high-density product comprising: a step of removing carbon dioxide gas contained in a produced gas containing methane gas by membrane separation; and a step of removing nitrogen gas contained in the produced gas by cryogenic separation. Method for producing calorie gas.