DE1567728B2 - PROCESS FOR GENERATING A GAS RICH IN HYDROGEN AND CARBON FROM CARBON DISTILLATION GASES - Google Patents

Description

The invention relates to a method for producing a gas rich in hydrogen and carbon oxide by catalytic cleavage of carbon distillation gases in the presence of water vapor and optionally Oxygen-containing gases, which are used as the starting gas for the production of a chemical Purposes of usable gas, e.g. B. a synthesis gas. The like, can be used.

The in the dry distillation of coal z. B. contain distillation gases occurring in coke ovens a number of accompanying substances, such as B. Benzene and naphthalene hydrocarbons, tar, hydrocyanic acid, Ammonia as well as hydrogen sulfide and organic sulfur compounds. It is already known from such gases remove the unwanted accompanying substances and the cleaned gas with water vapor and if necessary to convert air catalytically into a gas rich in hydrogen and carbon oxide. The catalytic cleavage usually takes place on nickel catalysts. The removal of the accompanying substances requires a complex work-up of the crude distillation gases, which also includes the accompanying substances arise as such, which either have to be destroyed or further processed.

It also includes a process for the purification of carbon distillation gases with the production of a fuel gas rich in carbon oxide and hydrogen from the state of the art, in which the crude distillation ^{gases are reacted at temperatures between 700 and 1300 0} C in the presence of gasifying agents using cracking catalysts and then those in the cracking gas remaining acidic impurities, such as B. hydrogen sulfide, can be removed from the cracked gas. The endothermic reaction must be carried out in chambers or the like, which are preferably externally heated and which consist of ceramic materials, since metallic materials cannot withstand the stresses occurring in the presence of the hydrogen sulfide contained in the gas to be cleaved. The use of ceramic building materials is disadvantageous in that, because of their low thermal conductivity and the greater wall thickness required compared to metallic materials, they require high boiler room temperatures and only allow a low heat flow per unit surface area of the chamber. Furthermore, the use of significantly increased operating pressures in chambers made of ceramic material is not possible. The known process also requires the use of sulfur-resistant catalysts and longer residence times, which are due to the fact that the activity of such catalysts, eg. B. that of nickel sulfide, is less than the activity of non-sulfur-resistant catalysts, e.g. B. of metallic nickel.

The invention is based on the object of carbon distillation gases waiving umstand- Γ Liehe and lengthy purification method, a make-rich gas to ^ hydrogen and carbon monoxide, wherein the disadvantages of the known method described are to be avoided, in which the raw distillation gases directly subjected to the catalytic cleavage will.

In a process for the production of gases rich in hydrogen and carbon oxide by catalytic cleavage of carbon distillation gases in the presence of water vapor and optionally oxygen-containing gases at temperatures between 600 and 1200 ⁰ C, in which the raw gases leaving the coke oven are cooled and after separation of the liquid hydrocarbons and the condensate water are compressed, the invention consists in that the gases then, before they are catalytically split, at a pressure of 1.5 to 30 ata, preferably 3 to 10 ata, and at temperatures between 250 and 700 ⁰ C, preferably 300 and 500 ° C, are catalytically hydrogenated and the hydrogen sulfide formed after ,, -

known cleaning process is removed. ^,

In the catalytic hydrogenation of the cooled gases, the cobalt-molybdenum catalysts is carried out in a known manner, are converted \ the organic sulfur compounds to hydrogen sulfide, whose distance beispiels-! can be done wisely with lawn iron ore or zinc oxide down to less than 10 ppm. During the hydrogenation of the gases, not only are the organic sulfur compounds converted into hydrogen sulfide and the accompanying substances such as hydrogen cyanide, ammonia and nitrogen oxide contained in the gas, to a greater or lesser extent, are broken down into their elements, but the olefins are also almost completely converted into saturated hydrocarbons. The additions still present in the hydrogenated gas after the removal of the hydrogen sulfide, such as. B. ammonia, traces of hydrocyanic acid and nitrogen oxides and the like do not interfere with the subsequent reaction. It has surprisingly been found that the conversion of the olefins can significantly increase the effectiveness of the catalyst in the reaction of the gases with water vapor and optionally oxygen or air, which makes it possible

the same implementation either with shorter dwell times, those that occur in liquid form when the raw gas is cooled times or at lower temperatures can be used by hydrocarbons. Who carry naphthalene than they can in the cleavage of non-hydrogenated hydrocarbons before or after the com-carbon distillation gas is required, its sulfur compression or also according to the individual compression sulfur content by other means, e.g. B. activated carbon can be removed in 5 stages.

the same value at the point of entry into the nickel- The catalytic conversion can be known at catalyst has been brought. The possibility of catalysts that do not swine need to be certain degree of turnover already at lower fefest; for example you can Being able to maintain temperatures is therefore a great advantage of nickel catalysts on a support material Advantage because the catalysts generally use ίο.

are arranged in metallic tubes and the application. The invention is based on two applications higher operating pressures with the same pipe routing examples with reference to the flow wall thickness is possible. scheme explained:

From the German patent specification 592 934 is a. .
Process for the production of hydrogen from gas 15 Example!
shaped hydrocarbons are known, in which one exiting from the template 1 of a coke oven the starting gases to remove higher molecular weight distillation gas was subjected to scrubbing with a suitable tar in a cooler 2 to a temperature of oil after separation of the thick hydrocarbons. In addition, the method provides for the 20 ⁰ C cooled. After removing the liquid starting gases to remove the sulfur compounds and washing the condensate dung with caustic soda, the gas had to be converted to the following mixture at 3 o'clock. Apart from the fact that the setting:

in the German patent 592 934 described /-.q 16

Process not based on distillation gases is ^^ hydrocarbons ". '.'. '.'. '.'. '.'. 2,3

it is more comparable to the known method, 25 ^ q - -

in those from the distillation gases before the kata- π "''" ^ q'ö

lyric conversion the unwanted accompanying pg '· 251

substances are removed than with the procedure according to ^ * ^ 6

of the present invention, in which practically un- ² '

purified gases, which, for example, still contained the organic 30 and contained the following accompanying substances per normal cubic meter

Contain sulfur compounds, catalytically hydrogenated substances:
and then implemented.

In the case of the US Pat. No. 1,673,032 containing 18 g of tar,

known processes that also do not apply to the 29.6 g benzene and homologues,

use of coke oven gas as starting gas directed 35 0.4 g naphthalene,

gases for the production of 9.3 g ammonia should also be used,

Hydrogen can be used, the unsaturated carbon 1.1 g hydrogen cyanide,

Contain hydrogen. For this purpose, the 7.6 g of hydrogen sulfide,

The starting gases are initially catalytically hydrogenated to remove the 0.5 g of organic sulfur compounds,

unsaturated hydrocarbons in a state 40 19 g water,
to bring in them for the conversion reaction

with steam in the presence of a suitable kata- This gas was compressed in three stages to 8.2 ata

lysators for the purpose of producing hydrogen and at temperatures of 380 to 400 ⁰ C

are suitable. The prerequisite for this is that the output at loads of about 2000 Nm ³ / m ³ / h in the

gases do not contain any sulfur compounds and. 45 ^{Stage 4} hydrogenated, with a measured volume

that these interfering compounds had previously been distantly reduced by about 6%. As a catalyst

Need to become. a cobalt-molybdenum catalyst was used. After

In contrast, the invention provides that the hydrogenation was the heavy content of the gas

raw distillation gases after cooling directly the hydrocarbons only 0.1 percent by volume,

subject to catalytic hydrogenation, then the 50 hydrocyanic acid and organic sulfur compounds

To remove hydrogen sulfide and then were only present in traces. The distance

to catalytically split the gas. the hydrogen sulfide from the hydrogenated gas

Since in most cases the gas produced is required in a known manner in the step e 5 by overpressure, another advantage of the process is that this pressure is already in the 55 45O ⁰ C to lead over lime at temperatures between 420 and to 6 to 8 ppm. The hydrogen sulfide precursors are present. The compression of the ge was deducted at 6.

The cooled gas can be carried out in several stages. The gas pre-cleaned in this way was mixed with water vapor

will. It is useful to remove the grains in a ratio of 1: 0.8 mixed and in stage 7

heat of compression converted to a nickel catalyst after the individual stages. The pressure

Way to make that the dew point for the still 60 at the entry into the catalyst was 1.6 ata, the

Naphthalene contained in the gas is not reached or even an outlet temperature of 850 ° C with residence times of

is fallen below. less than a second. That is how-

In a further embodiment of the Vertene gas had the following composition:

Driving according to the present invention, one can avoid CO ₂ 3.0

the hydrogenation contained 65 CO 17.3 in the cooled gas

Hydrogen sulfide and the naphthalene carbon H ₂ 75.4

Remove all or part of the hydrogen. For Ent- CH ₄ 1.7

Removal of the naphthalene hydrocarbons can be N ₂ 2.6

5 6

In relation to the coal-cleaned gas originally used, steam was mixed with

distillation gas, the volume increase was about a ratio of about 1: 0.8 mixed and in the presence

100% · The gas still contained about nickel on carrier material per cubic meter at a pressure of

3 ppm hydrogen sulfide and about 180 g of water 8 ata and a temperature of 900 ⁰ C implemented,

and about 0.03 g of ammonia. The methane conversion 5. The space velocity over the catalyst was about 1200 Nm ³ / m ³ / h.

was based on the originally present The gas obtained had the following composition:

Amount, about 87% · CO 3 5

When splitting a coal distillation gas, qq ² ■, Sq

that is not subject to a previous hydrogenation yg'o

was thrown and also only 6 to 8 ppm sulfur io p | j q'o

hydrogen at the entry into the cracking catalyst ent- ^ ⁴ 2'r

held, was under the same operating conditions ² '

only achieved a methane conversion of about 73%. The increase in volume was based on the

. . originally used coal distillation gas, about

Example 2 _{£ 1} . ₁₂₅ o / _o _

The carbon distillation gas used in Example 1 When a non-hydrogenated coal was cracked, as in the previous example, distillation gas with the same sulfur content was hydrogenated and the hydrogen sulfide after the hydrogenation under the same operating conditions was obtained by passing it over a zinc oxide mass with a methane content of 0, 8 percent by volume in the end gas up to 400 ⁰ C removed down to 2 to 4 ppm. To achieve this before 20 a temperature of 965 ° C is required.

1 sheet of drawings

Claims (3)

Patent claims: 1. Process for the production of gases rich in hydrogen and carbon oxide by catalytic cleavage of carbon distillation gases in the presence of water vapor and optionally oxygen-containing gases at temperatures between 600 and 1200 ⁰ C, in which the raw gases leaving the coke oven are cooled and after separation of the liquid hydrocarbons and the condensate water are compressed, characterized in that the gases then, before they are catalytically split, at a pressure of 1.5 to 30 ata, preferably 3 to 10 ata, and at temperatures between 250 and 700 ⁰ C, preferably 300 to 500 ⁰ C, are catalytically hydrogenated and the hydrogen sulfide formed is removed by known purification processes. 2. The method according to claim 1, characterized in that the contained in the cooled gas Hydrogen sulfide is completely or partially removed before the hydrogenation. 3. The method according to claims 1 and 2, characterized in that from the cooled Gas the naphthalene hydrocarbons contained therein in whole or in part before the hydrogenation removed.