JPS61186203A - Purification of coke oven gas - Google Patents

Abstract

PURPOSE:Coke-oven gas is brought into contact with a porous substance, then hydrogenated in the presence of a specific catalyst and hydrogen sulfide is removed to enable high-efficiency removal of impurities in coke-oven gas. CONSTITUTION:(a) A coke-oven gas containing, as impurities, tar oils, gums, dienes, oxygen, olefins, sulfur compounds is brought into contact with a porous substance to remove tar oils and gums by adsorption. Then, (b) dienes and oxygen remaining in the treated gas is hydrogenated in the presence of a catalyst of a noble metal in the group VIII on a carrier. Subsequently, (c) the olefins and sulfur compounds remaining in the resultant coke-oven gas are hydrogenated. Finally, (d) the hydrogen sulfide in the gas from the step (c) is removed by absorption.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a method for removing impurities from coke oven gas, particularly tar oil, gum substances, dienes, oxygen, olefins and sulfur compounds in coke oven gas. This invention relates to a coke oven gas nM method suitable for removing.

[Background of the invention]

Conventional coke oven gas purification methods include hydrogenation of dienes, oxygen, olefins, and sulfur compounds through a hydrodesulfurization process using a catalyst system containing nickel and/or cobalt and molybdenum. It is being For example rPROcE88E8FORTHE MANU
FACTUR,E OF NATURALT-GA
S 8UBSTITUTE8J Gas Count
ill(search Communication
QC155.

See November, 1968, pages 14-15. However, these conventional methods have a problem in that the tar oil contained in the coke oven gas covers the catalyst active sites, significantly reducing the catalyst activity.

Furthermore, the dienes, oxygen, and nitrogen oxides in the coke oven gas polymerize to form a gum-like substance that clogs equipment, piping, etc. upstream of the catalyst layer, and causes problems such as blockage of the catalyst layer. There was a drawback.

[Purpose of the invention]

An object of the present invention is to provide a method for purifying coke oven gas that efficiently removes tar oil, gum substances, dienes, oxygen, olefins, and sulfur compounds contained in coke oven gas by a combination of steps. be.

[Summary of the invention]

To summarize the present invention, the present invention provides a method for purifying coke oven gas containing at least tar oil and gum substances as impurities, in which the coke oven gas is brought into contact with a porous material to adsorb and remove the tar oil and gum substances. an adsorption step in which the dienes, oxygen, and olefins remaining in the coke oven gas from the adsorption step are mainly hydrogenated in the presence of a catalyst in which a noble metal of photogroup (I) of the periodic law is supported on a carrier; a second hydrogenation step in which olefins and sulfur compounds remaining in the coke oven gas from the first hydrogenation step are mainly hydrogenated; and hydrogen sulfide in the coke oven gas from the second hydrogenation step. It is characterized by including each step of the hydrogen sulfide removal step of absorption and removal.

The porous material used in the first step, the adsorption step (hereinafter referred to as
Examples of adsorbents (abbreviated as adsorbents) include those selected from the group consisting of alumina, silica, zeolites, iron oxides, titania, magnesia, diatomaceous earth, calcium oxides, zirconia, activated carbon and mixtures thereof. Particularly preferred are alumina, silica, and activated carbon.

The adsorbent desirably has a BET surface area of 10 m2/g or more, particularly preferably 20 m2 to 1000 m''
It is in the range of 7g. Pore volume is 0, 10 nle/
g or more is preferable, particularly preferably 0.15 to 0.60
ml/H range - C"6.It adhesive has high hygroscopicity and adsorbs moisture in the air, reducing adsorption performance, so keep it at an appropriate temperature, preferably 300 to 400 C, before use.
It is preferable to dry at a temperature of . A suitable temperature for adsorption carried out using an adsorbent is in the range of room temperature to 300C, preferably in the range of room temperature to 200C. If it exceeds 300t:', the adsorption performance will decrease. The coke oven gas supply rate to this adsorbent is 100 to 10.0 in terms of space velocity.
0011-1 is preferred. If the space velocity is less than 100 h-1, the amount of adsorption used will be large, making it uneconomical;
,000 h-1, the adsorption capacity decreases. The pressure at which adsorption is carried out is not limited, but 2 to 100 atmospheres is particularly desirable.

The catalyst used in the first hydrogenation step after adsorption of tar oil and gummy substances is a platinum group metal catalyst selected from Group Ⅰ of the periodic table, and the carrier is ruthenium, rhodium, palladium,
It supports at least one of osmium, iridium, and platinum. At least one of alumina, titania, and magnesia is suitable as the carrier. Particularly preferred compositions of the catalyst include platinum group metals, such as ruthenium, rhodium, palladium, osmium, iridium, and platinum, in an amount of 0.1 to 5% by weight, and a carrier in a proportion of 99.9 to 95% by weight. . These catalysts almost completely hydrogenate impurities such as dienes, oxygen, and olefins in the coke oven gas. The present inventors have discovered that oxygen, -nitrogen oxide, and dienes contained in coke oven gas polymerize to produce a gummy substance, which can clog the catalyst layer and equipment and piping upstream of the catalyst layer, and It was confirmed through experiments that the activity could be reduced. In order to prevent the formation of this polymer, we installed a first hydrogenation process in which dienes and oxygen, which cause clogging in low-temperature ranges, are hydrogenated before the process of mainly hydrogenating sulfur compounds. It was also confirmed that the decrease in the activity of the catalyst in the second hydrogenation step, which is used to hydrogenate sulfur compounds and sulfur compounds, was also very small.

In the second hydrogenation step after the first hydrogenation step, it is preferable to use a catalyst containing nickel and/or cobalt and molybdenum as a catalyst for hydrogenating olefins and sulfur compounds. For example, N10Mo0a AAllo
, CoOMo0a Atgos, etc., and is reduced during normal use. It is preferable to use it after sulfurizing it with hydrogen sulfide, 4 disulfide, thiophene, etc. in order to suppress the mixture reaction. The preferred composition of the second hydrogenation catalyst is 1 to 15 parts of nickel and/or cobalt! :%
, molybdenum accounts for i~45% by weight, and the remainder is alumina.

The temperature of the hydrogenation reaction in the first hydrogenation step is the inlet temperature of 100
The temperature should be in the range of ~230 C, preferably 150-200 C, and the catalyst layer should be in the range of 100-35 (1
, preferably in the range 150-300C. If the inlet temperature of the first hydrogenation step is less than 100C,
Hydrogenation activity is insufficient and dienes and oxygen flow out from the first hydrogenation step to the second hydrogenation step. The temperature of the hydrogenation reaction in the second hydrogenation step should not exceed 450C, preferably 410C or less. When the temperature exceeds 450C, the reaction rate of carbon monoxide and carbon dioxide gas methanation is large, causing a large temperature rise in the catalyst layer and causing a sluggish phenomenon of the catalyst. If the temperature exceeds 500C, troubles such as carbon precipitation due to decomposition of hydrocarbons may occur. On the other hand, below 250C, the hydrodesulfurization activity is not sufficient. In order to particularly increase the hydrogenation activity of thiophene among sulfur compounds, the temperature is maintained at 300C or higher, preferably 350C or higher.

Any known method can be used to remove hydrogen sulfide after hydrodesulfurization. For example, ZnO, Fez
This method uses solid adsorbents such as es, Cub, and activated carbon.

Coke oven gas contains 0.1 to 2.0 volumes of oxygen, and when 1.0 volumes of oxygen reacts, 150%
There is a temperature rise of C. In addition, coke oven gas contains 10 to 5.0 volumes of olefins, and when olefins react with 1.0 volumes, the temperature rises by 30C.
In order to suppress this reaction heat, it is sufficient to monitor the temperature rise of the catalyst layer and recirculate a portion of the purified gas to dilute the oxygen and olefin concentrations at the inlet.

The present invention may include a step of circulating a part of the coke oven gas purified in this manner to a stage before or after the adsorption step. By circulating the purified gas, it is possible to easily control the temperature of the hydrogenation reaction in the first hydrogenation step. The amount of gas circulated at this time is preferably in the range of 10 to 1000% of the raw coke oven gas. The amount of gas to be circulated is selected and adjusted within a range such that the temperature in the first hydrogenation step is kept at 350 υ or less and the temperature in the second hydrogenation step is kept at 450 c or less.

The coke oven gas supply rate in the first hydrogenation step and the second hydrogenation step is 500 to 50,000 in terms of space velocity (S, V,)
h-1 is preferred. When the space velocity is less than 500 h-1, the amount of catalyst used becomes large and becomes uneconomical;
,000 h-1, the hydrogenation activity will not be sufficient. The pressure may be 2 to 100 atmospheres, but is not particularly limited.

As the pressure becomes higher, the rate of methanation reactions of carbon monoxide and carbon dioxide gas in coke oven gas increases as side reactions.

Next, the process for carrying out the present invention will be specifically explained with reference to the drawings. That is, FIG. 1 is a process diagram showing an embodiment of the present invention, in which 1 is a coke oven gas, 2 is an adsorption tower, 3 is a first hydrogenation tower, 4 is a heating furnace, and 5 is a second hydrogenation tower. tower,
6 means a hydrogen sulfide absorption tower, and 8 means purified gas. Further, FIG. 2 is a process diagram showing an embodiment of the present invention in which a part of the purified gas is recirculated to the inlet or outlet of the adsorption process, and 1 to 6 and 8 have the same meanings as in FIG. 1. and 7 means a circulation line. The drawings include only the main parts necessary for understanding the present invention, and other devices such as a circulator, a cooler, a measuring device, a control, a rotation, and other devices are omitted.

[Embodiments of the invention]

Next, the present invention will be further explained with reference to Examples, but the present invention is not limited thereto.

Example 1 In FIG. 1, the coke oven gas 1 is approximately 150 to 200C.
is heated to a temperature of This adsorption tower 2 has a BET surface area of 320 m"/g average pore volume 'MR
Filled with 0,18 ml/H alumina. The composition of the main components of coke oven gas is %, CH4 is 30.
67%, CzH4 1.60%.

C3H6 is 1.60%, Oz is 0.594, C4H
6 is 0.10 inch, sulfur compound is 0.01 inch, N2 is 4.
18%, of which tar oil and gum substances are 1.
0 mg/N m''. The aluminum in adsorption tower 2 adsorbs and removes tar oil and gum substances in the coke oven gas. Tar oil and gum substances in the gas at the outlet of the adsorption tower are 0.
．． 1 mg/Nm” or less and 99. On
The above tar oil and gum substances were adsorbed and removed.

Example 2 This example shows the results of investigating the adsorption and removal performance of tar oil and gum substances when using adsorbents other than alumina. Adsorption temperature 1807:', space velocity (S, V,) 2
．． I went with ooo h-t. The results obtained are shown in Table 1.

Table 1 Example 3 In this example, using alumina with a BET surface area of 320 m'' and 7 g, the relationship between adsorption temperature and adsorption removal performance of tar oil and gum substances was investigated at a space velocity (S, V, ) of 5,000 h-s. The results are shown in Table 2.

Table 2 Example 4 The raw material coke oven gas having the composition described in Example 1 was
At temperatures between 50 and 200c, the BET surface area aoom”/g
s Pore volume 0.15 ml/g (7) 7/L=
The mixture is introduced into an adsorption tower filled with Mina adsorbent. Tar oil and gum substances are almost completely adsorbed and removed.

The gas composition at the outlet of the O adsorption tower is H2: 53.2596. h is 5
, 89%, C02 2.20%, CH4 30.67
%.

C2H4 is 1.60%, Ca Ha is 1.60%,
Ox is 0.5096.04 H6 is 0.10%, sulfur compound is 0.01%l, N2 is 4.18h.

The gas leaving the adsorption tower is introduced into the first hydrogenation tower 3 at a temperature of about 150-200C. The catalyst in the first hydrogenation column is one in which 0.57% of palladium is supported on an alumina phase.

In the first hydrogenation tower, dienes, oxygen, and olefins in the coke oven gas are almost completely hydrogenated and removed. Hydrogenation of olefins is 10-20% after approximately 4000 hours of operation.
It is discharged to the second hydrogenation step.

At the beginning of operation, the purified coke oven gas is 32
C02 exiting the first hydrogenation tower 3 at a temperature of 0 to 370C is 2.2
1ch, CH4 is 30.82ch, C2H6 is 1.61
To, C3H5 is 1.61 To, C4Hto is 0
．． 1 thi, sulfur compound 0.01 thi, N2 becomes 4.2096.

In addition, by using the process shown in Fig. 2 and circulating the circulating gas 7 at 100% of the amount of raw coke oven gas, the oxygen and olefins at the entrance of the adsorption tower are diluted and the temperature of the first hydrogenation tower is lowered. was adjusted to a temperature of 240-290C.

Furthermore, when an adsorption tower was provided according to the present invention, the catalyst life was dramatically improved. For example, if an adsorption tower was not provided, the catalyst would become unusable after about 10,000 hours, but in the case of the example of the present invention, it was possible to operate without trouble for more than 4,000 hours.

The generated gas is heated to about 320 to 350 C in a heating furnace 4 and supplied to a second hydrogenation tower 5. The sulfur compounds remaining in the coke oven gas and the olefins discharged from the first hydrogenation tower are completely hydrogenated in the second hydrogenation tower. The catalyst in the second hydrogenation tower contains 3% by weight of nickel and 7% by weight of molybdenum on an alumina carrier.
The weight percentages are compatible. The temperature of the second hydrogenation tower is approximately 35
The temperature will be between 0 and 380C.

The gas exiting the second hydrogenation tower is introduced into the hydrogen sulfide removal tower 6 at a temperature of about 350 to 3801:l', where hydrogen sulfide in the coke oven gas is absorbed and removed. Thus, the essence CH4 is 30.
82. C2Ha is 1.61%, Cs Hs is 1.6
1%, C4Hlo was 0.10%, and NR was 4.20.

〔Effect of the invention〕

As is clear from the above detailed description, according to the present invention, tar oil and gum substances in coke oven gas can be efficiently removed, and dienes and oxygen contained in coke oven gas can be efficiently removed.
Among olefins and sulfur compounds, the first hydrogenation catalyst is used to hydrogenate mainly gens and oxygen at low temperatures, and the second hydrogenation catalyst is used to hydrogenate the remaining sulfur compounds and olefins from the first hydrogenation catalyst. This has the remarkable effect of suppressing the formation of gummy substances due to diene polymerization and efficiently purifying coke oven gas.

[Brief explanation of the drawing]

Fig. 1 is a process diagram showing an embodiment of the present invention, and Fig. 2 is a process diagram showing an embodiment in which a part of the purified gas is recirculated to the inlet or outlet of the adsorption process in the present invention. It is. DESCRIPTION OF SYMBOLS 1... Coke oven gas, 2... Adsorption tower, 3... First hydrogenation tower, 4... Heating furnace, 5... Second hydrogenation tower, 6...
...Hydrogen sulfide absorption tower, 7...Circulation line, 8...Purified gas.

Claims (1)

[Claims] 1. Impurities include tar oil, gum substances, dienes,
A method for purifying coke oven gas containing oxygen, olefins, and sulfur compounds, an adsorption step of bringing the coke oven gas into contact with a porous material to adsorb and remove tar oil and gum materials; a coke oven from the adsorption step; The first step is to hydrogenate the dienes and oxygen remaining in the gas in the presence of a catalyst containing a noble metal from Group VIII of the Periodic Table on a carrier.
a hydrogenation step, a second step in which olefins and sulfur compounds remaining in the coke oven gas from the first hydrogenation step are hydrogenated;
A method for purifying coke oven gas, comprising the steps of a hydrogenation step and a hydrogen sulfide removal step of absorbing and removing hydrogen sulfide in the coke oven gas from the second hydrogenation step. 2. Part of the purified gas from the hydrogen sulfide removal step is recycled to the previous stage of the adsorption step, and the temperature of the first hydrogenation step is 350°C.
The method for purifying coke oven gas according to claim 1, characterized in that the temperature in the second hydrogenation step is controlled so as not to exceed 450°C. 3. Part of the purified gas from the hydrogen sulfide removal step is recycled to the latter stage of the adsorption step, and the temperature of the first hydrogenation step is 35.
The method for purifying coke oven gas according to claim 1, characterized in that the temperature in the second hydrogenation step is controlled so as not to exceed 0°C and the temperature in the second hydrogenation step not to exceed 450°C. 4. Add the recirculated gas to 1% of the amount of raw material coke oven gas.
The method for purifying coke oven gas according to claim 2 or 3, characterized in that the coke oven gas is supplied at a ratio of 0 to 1000%. 5. The method for purifying coke oven gas according to claim 1, characterized in that the inlet temperature of the first hydrogenation step is adjusted to a temperature within the range of 100 to 230°C. 6. The method for purifying coke oven gas according to claim 1, characterized in that the temperature of the adsorption step is adjusted to 300° C. or lower. 7. The porous material used in the adsorption step has a BET surface area of 10 m^2/g or more and a pore volume of 0.10 ml/g.
2. The method for purifying coke oven gas according to claim 1, wherein the coke oven gas purification method is at least 100 g. 8. The method for purifying coke oven gas according to claim 1, wherein the porous material is selected from the group consisting of alumina, silica, activated carbon, and mixtures thereof. 9. The catalyst used in the first hydrogenation step contains 0.1 to 5% by weight of a noble metal belonging to Group VIII of the Periodic Table and 99.9 to 95% by weight of a carrier. A method for purifying coke oven gas according to claim 1. 10. The method for purifying coke oven gas according to claim 1, wherein the catalyst carrier used in the first hydrogenation step is made of at least one of alumina, titania, and magnesia. 11. The catalyst used in the second hydrogenation step is nickel and/or
Or 1 to 15% by weight of cobalt and 3 to 45% of molybdenum
% and alumina in a proportion of 96 to 40% by weight.