JPS6189294A - Method of purifying coke oven gas - Google Patents

Abstract

PURPOSE:To purify a coke oven gas in such a way that it is suitable for producing hydrogen or as a synthesis gas, by hydrogenating selectively unsaturated hydrocarbons and oxygen in the coke oven gas by the use of a Pd catalyst. CONSTITUTION:A coke oven gas, preferably previously, sent to a hot bottle, subjected to oil washing, and cooled, so that it is pretreated. Then, it is brought into contact with a Pd catalyst, and unsaturated hydrocarbons such as dienes, olefins, etc. and oxygen are selectively hydrogenated. Then, sulfides are subjected to desulfurized through hydrogenation in the presence of a catalyst, and hydrogen is separated and recovered with an adsorbent such as zeolite, etc., to purify the coke oven gas.

Description

[Detailed Description of the Invention] (Field to which the invention pertains) The present invention relates to a method for purifying coke oven gas, and more specifically to a method for eliminating unsaturated hydrocarbons such as dienes, oxygen, etc. that impede the advanced utilization of coke oven gas. The present invention relates to a coke oven gas mWIJ method in which residual substances are selectively hydrogenated with a palladium catalyst so that the coke oven gas can be used as a raw material gas for hydrogen production or as synthesis gas.

(Background of the Invention) During the production of coke, the high-temperature carbonization gas generated contains a wide variety of substances. After processing such as removal, 50-60% of hydrogen is removed.
, the coke oven gas contains about 5 to 10% CO and about 20 to 35% lower hydrocarbons. Although the composition of this coke oven gas varies slightly depending on the raw material coal, carbonization column ('F J3), and the treatment method of carbonization gas, as mentioned above, it is mainly composed of hydrogen, carbon oxide, and lower hydrocarbons. There is no difference. However, these coke oven gases contain unsaturated hydrocarbons such as dienes, which are easy to transport, nitrogen oxides and oxygen, which act as triggers for the polymerization of unsaturated hydrocarbons, and trace amounts of organic sulfur compounds. In addition to hydrogen sulfide, it also contains unremoved aromatic compounds.

Therefore, although coke oven gas is rich in hydrogen and carbon oxide, the reality is that it cannot be directly used as a raw material for hydrogen or synthesis gas, and is instead used as a fuel.

When trying to use coke oven gas as raw material gas,
Troubles such as blockage of one vessel (due to polymerization products of unsaturated hydrocarbons or polymerization products caused by NOx) or precipitation of elemental sulfur caused by the coexistence of oxygen and hydrogen sulfide and resulting blockage of equipment may occur. be.

(Description of the prior art) As an attempt to reduce the amount of coke oven gas,
It is known to remove NOx by increasing the temperature of coke oven gas, and to remove tar mist and aromatic IJ'A compounds by treatment with absorption oil. That is, according to the above process, NOx
, aromatic compounds, and oil mist are almost completely removed. However, hydrogen sulfide, organic sulfur, dienes, and oxygen remain. Such coexistence of hydrogen sulfide and oxygen is not preferable because elemental sulfur will precipitate when zeolite adsorption is used to purify coke oven gas.

As a method for further purifying this coke oven gas, there is a method disclosed in Japanese Patent Publication No. 58-12318. The invention disclosed in the publication involves heating coke oven gas, applying back pressure, oil washing,
After surface treatment such as rapid cooling, the coke oven gas is brought into contact with a hydrodesulfurization catalyst to selectively hydrogenate dienes, oxygen, and sulfides. However, in this method, since a hydrodesulfurization catalyst is used, the reaction is
When carried out at a low temperature of 200° C., unsaturated hydrocarbons such as acetin and diene can be hydrogenated, but sulfur dioxide gas is produced as a by-product, which may lead to corrosion problems.

Additionally, if the reaction is carried out at temperatures above 200°C, organic acids will be produced as by-products, leading to corrosion of pipes, and since hydrogenation of olefins is insufficient, the hydrogen sulfide produced will be added to unsaturated hydrocarbons, creating new organic sulfur. Compounds may be synthesized.

As described above, the reality is that a method for effectively removing unsaturated hydrocarbons such as dienes, acetylenes, and olefins, sulfides, and Wm from coke oven gas needs to be improved.

(Object of the Invention) The present invention has been made in view of the above problems, and is a method for effectively removing impurities such as unsaturated hydrocarbons from coke oven gas.
The porpose is to do.

(Structure of the Invention) The present inventors have solved the above object by hydrogenating coke oven gas using a palladium catalyst.

The present invention resides in a VJ manufacturing method for coke oven gas, which is characterized by hydrogenating coke oven gas to remove unsaturated hydrocarbons and oxygen using a palladium catalyst.

In the present invention, the coke oven gas is first heated to 60 to 150
Increase temperature to ℃. If the coke oven gas contains aromatic compounds and nitrogen oxides, 5 to 50/(g/
After increasing the pressure to CTRR G, NOx, acetylenes, and dienes are polymerized and removed in a hot bottle, and then washed with absorbing oil such as gas oil to remove heavy hydrocarbons, naphthalene,
Aromatic compounds and the like are removed, and the mixture is roughly cooled to precipitate and remove naphthalene and the like. Substantially no NOx or aromatic compounds remain in the coke oven gas that has been treated in this way.

Next, this coke oven gas is brought into contact with a palladium catalyst to selectively hydrogenate unsaturated hydrocarbons such as dienes and olefins and oxygen. Even in the presence of an organic sulfur compound, the palladium catalyst can sufficiently hydrogenate unsaturated hydrocarbons such as olefins and dienes and oxygen by raising the catalyst layer inlet temperature to 1'00 to 200°C. For this reason, hydrogen sulfide is not added to residual olefins, etc., and new 81-sulfur compounds are not produced as by-products, and organic acids are not produced as by-products from olefins, etc., carbon monoxide, and water vapor. No problems arise. In addition, the palladium catalyst is 1
It exhibits sufficiently high catalytic activity at temperatures of 00 to 200°C. Therefore, when the inlet temperature of the palladium catalyst is set within this range, the hydrogenation reaction in the palladium catalyst is an IIRM elementary reaction and a hydrogenation reaction of ethylene, etc., and is an exothermic reaction. Although there are fluctuations, the palladium catalyst outlet temperature is 270 to 330°C.

Therefore, in the present invention, the hydrogenation reaction can be carried out adiabatically using an adiabatic reactor without requiring an externally cooled reactor that is normally used for hydrogenation.

The palladium catalyst used here is not particularly limited, but
In general, palladium catalysts with low residual chlorine should be used, and those in which alumina is impregnated with palladium chloride and chlorine ions are removed by hydrogen reduction are easy to form polymers at low temperatures and produce a large amount of acid as a by-product. . however,
Even when palladium chloride was used, the product obtained by the method disclosed in Japanese Patent Application No. 59-43981 had high activity. In addition, 1it' [palladium impregnated into alumina and decomposed to remove nitrate ions was also highly active.

The coke oven gas in which unsaturated hydrocarbons such as olefins and dienes and oxygen have been hydrogenated is then subjected to hydrodesulfurization to desulfurize sulfides such as organic sulfur compounds, and hydrogenated by zeolite absorption 45. The minute is 1.

The catalyst used for hydrodesulfurization is a nickel catalyst, Ni1ylo.
A conventional hydrodesulfurization catalyst such as a CoMo catalyst is used. In this hydrodesulfurization, unsaturated hydrocarbons such as olefins in coke oven gas are sufficiently hydrogenated by hydrogenation using a palladium catalyst, so olefins and hydrogen sulfide react to form organic sulfur compounds. There's nothing to do.

The hydrodesulfurization catalyst used here is preferably presulfurized, and the desulfurization temperature is preferably 270 to 330°C. The reason for this is that when carbon oxide coexists, the hydrogenation rate of sulfur decreases significantly. Therefore, it is necessary to reduce the superficial gas velocity, but at high temperatures of 330° C. or higher, there is a risk that methanation will occur even with the hydrodesulfurization catalyst. Therefore, it is desirable to set the desulfurization fA degree to 1270 to 330°C.
There is also the advantage that preheating with a hydrodesulfurization catalyst such as a catalyst is not required.

Furthermore, since the hydrogenation reaction using a palladium catalyst is an exothermic reaction as described above, the temperature at the outlet of the palladium catalyst is approximately 270 to 330°C.

For this reason, heating is not required between the palladium catalyst and the hydrodesulfurization catalyst. Furthermore, in hydrodesulfurization, unsaturated hydrocarbons such as olefins are not hydrogenated or methanated, and no accompanying heat is generated, so there is no need for recycling to prevent temperature rise.

When hydrogen is separated by adsorption using zeolite or the like after hydrogenation using a palladium catalyst, oxygen and hydrogen sulfide do not coexist, so the problem of elemental sulfur precipitating does not occur. Further, hydrogen can be recovered without any trouble by either the cryogenic separation method or the method using a separation membrane.

(Description of Examples and Comparative Examples) The present invention will be specifically described below based on Examples and Comparative Examples.

Comparative Example Coke oven gas having the composition shown in Table 1 was subjected to pretreatment of hot bottling, oil washing, and cooling according to the flow shown in FIG. 1, and then hydrogenated using a NiMo catalyst. This N1
Table 1 shows the composition of the coke oven gas at the outlet of the M0 catalyst bed. Note that the NiMo catalyst layer uses an externally cooled reactor,
280℃, pressure 17'j/ci-G, SV
= 30001/hr Te row ivy.

Example Coke oven gas having the composition shown in Table 1 was subjected to pretreatment of hot bottling, oil washing, and cooling according to the flow shown in Figure 2, and then an adiabatic reactor was set up and filled with palladium catalyst. As a result of setting the inlet temperature to 150° C., the outlet temperature became 280° C., and the material was directly fed into the N1M0 catalyst bed for hydrodesulfurization.

This palladium catalyst layer outlet and NIMO catalyst PI'>
The composition of the coke oven gas at the outlet is shown in Table 1.

Note that there was no need to cool the NiMo catalyst layer.

As shown in Table 81, the composition of the coke oven gas at the outlet of the N1M0 catalyst layer in the comparative example contains a considerable amount of olefins, dioxylic acids, and organic sulfur compounds, but the composition of the coke oven gas at the outlet of the palladium catalyst layer in the example It was found that the composition contained no olefins or organic acids, that the olefins were completely hydrogenated, and that no organic acids were produced as by-products. Furthermore, it was found that the organic sulfur compounds were completely hydrogenated in the coke oven gas composition at the outlet of the NiMo catalyst layer in the example.

(Effects of the Invention) As described above, the coke oven refining method of the present invention, in which coke oven gas is selectively hydrogenated to remove unsaturated hydrocarbons such as olefins and oxygen using a palladium catalyst, has the following effects.

(2): 63% in hydrogenation using palladium catalyst, less by-product of 11 acids.

(2): It is easy to form a hydrogenated film I11!1 of an organic sulfur compound in a subsequent step.

■: Since the hydrogenation reaction of palladium catalyst is an exothermic reaction,
An externally cooled reactor is not required, making it possible to use an adiabatic reactor.

[Brief explanation of the drawings] Figure 1 shows 70 of the coke oven gas purification methods used in the comparative example.
1 and 2 are the flowcharts of method J for coke oven gas used in the examples.

Claims (1)

[Claims] 1. A method for purifying coke oven gas, which comprises hydrogenating coke oven gas to remove unsaturated hydrocarbons and oxygen using a palladium catalyst. 2. The method for refining coke oven gas according to claim 1, wherein hot bottling, oil washing, and cooling are performed as pretreatments before the hydrogenation using the palladium catalyst. 3. After the hydrogenation using the palladium catalyst, the sulfide is hydrodesulfurized using a hydrodesulfurization catalyst.
The method for purifying coke oven gas according to item 1 or 2. 4. The coke oven gas purification method according to claim 1 or 2, wherein after hydrogenation using the palladium catalyst, adsorption separation is performed using an adsorbent to recover hydrogen. 5. The method for purifying coke oven gas according to claim 4, wherein the adsorbent is zeolite.