DE1567683A1 - Process for the flameless conversion of gaseous and / or liquid hydrocarbons to gases, in particular gases with high heating power - Google Patents

Description

METALLGESELLSCHAFT "Frankfurt (Main), April 23, 1965

Public company DrWer / SH

768 3

prov. No. 4616

Dr. Expl.

Process for the flameless conversion of gaseous and / or liquid hydrocarbons to gases, in particular gases with a high heat

It is known to be gaseous hydrocarbons, liquefied gases and liquid Hydrocarbons in insufficient quantities for complete combustion Oxygen, optionally with the addition of steam and / or Carbon dioxide, on catalysts, especially on nickel catalysts without To implement flame formation to synthesis gases or heating gases. If that The gas produced should be free of nitrogen, becomes purer as a gasification agent Uses oxygen. Otherwise air or air-oxygen mixtures are sufficient. The catalysts used are nickel catalysts, which are the active metal on carrier materials such as magnesium oxide or aluminum oxide.

Catalysts that contain nickel on magnesium oxide as a carrier substance, have proven themselves in the flameless oxidative cleavage of gaseous hydrocarbons, as long as the reactants are at least 550 C are preheated.

If this preheating temperature is not reached more often or for a longer period of time, What can never be completely avoided under the operating conditions of a technical system that is in continuous operation, then arise

009828/0343 " ² -

Damage to the catalyst caused by hydration of the Magnesium oxide are caused. It has been shown that this Hydration is temperature dependent and particularly severe at operating temperatures of the catalyst occurs between about 400 and 600 ° C. If the preheating temperature frequently falls below 550 C, the will call Hydration of the magnesia support reduces the volume of the catalyst emerged. Due to the shrinkage of the catalyst filling the reaction space, part of this space is at the inlet of the Respondents free. In this, pre-combustion of the reaction mixture takes place, which hit back into the mixing devices of the reaction participants and cause considerable damage there. Will Liquefied gases or liquid hydrocarbons on nickel on a catalyzer containing magnesium oxide are split in a flameless oxidizing manner, Then the difficulties just described and observed in the splitting of gaseous hydrocarbons due to hydration arise of the catalyst support to a much greater extent, and the catalyst becomes unusable after an unforeseeable, very short operating time. This is based on the fact that the liquefied gases and even more the liquid hydrocarbons, e.g. B. Gasoline, even at preheating temperatures tend to thermal decomposition above 450 ° C, in which they are covered with soot «, deposits become dehydrated.

009828/0343

By adding steam before the coals are heated to the top « Hydrogen can moderate this tendency, but not completely eliminate it will. This addition of water vapor promotes the hydration of the nickel-magnesia contact. One can do the hydration of the nickel-magnesia contact and. limit the resulting shrinkage very far, if you are on the inlet side of the reactants on the catalyst layer piling up a layer of inert granular material. This liiertschicht prevents re-ignition in the mixing devices. In addition, the temperature of the reactants in this inner zone is controlled by a Partial reaction raised to such an extent that the temperature range of hydration in the magnesite contact is exceeded. The dimensioning of the The bed height of this inert layer is very difficult because it depends on the load on the system and the particular composition of the starting mixture the respondent depends.

If the luert layer is too high, considerable exotherms can occur in this layer Reactions occur that are not slowed down by simultaneous endothermic reactions. Then there is a considerable increase in temperature, which can lead to the destruction of the inert layer and strong soot formation causes. An inert layer that is too shallow is ineffective because it gets into the catalyst bed entering reaction mixture does not have a sufficient temperature to stop hydration. With one under fluctuating loads

00 98 28/034 3 - ⁴ -

and changing raw materials is in continuous operation it is practically not possible to dimension the inert layer so that it can effectively prevent the difficulties mentioned ".

By connecting "ignition contacts", which are caused by partial combustion of hydrocarbons with the free oxygen, the temperatures of the reaction mixture before it enters the nickel-magnesia catalyst increase to temperatures of over 600 C, permanent maintenance of contact activity cannot be achieved. The activity of these ignition contacts sinks rapidly and usually lasts only a few months. This contributes to a high degree Measures that these ignition contacts, the z. B. contain platinum on ceramic carrier materials, are sensitive to sulfur and are very extensive Desulfurization of the feed hydrocarbons require, which reduces the economic efficiency of the process. »

On nickel catalysts that contain aluminum oxide as a carrier substance, hydration processes have not yet been observed »The oxidative cleavage of hydrocarbons on nickel-alumina catalysts is required significantly higher steam additions to the reaction mixture in order to avoid soot formation. These steam additives are particularly useful when using liquid Hydrocarbons are so high that this work is no longer economically viable.

009828/0343 ~ ⁵ ~

It has now been found that the described disadvantages of both catalysts " types can be avoided by using a nickel catalyst a support made of magnesium oxide, a nickel catalyst on a support made of aluminum oxide.

This series connection is with low additional steam that with the exclusive use of nickel-alumina catalysts for Lead to soot formation, no soot to be found in the cracked gas generated. That is probably based on the fact that intermediate on the Nickei "clay * Small amounts of soot formed by the catalyst are re-gasified in the subsequent layer of the nickel-magnesia catalyst and do not result in any Process disruptions. In-depth research has shown that the quantitative ratio of the two types of catalyst can be varied in a wide ratio without soot formation on the nickel-alumina catalyst or pre-ignition and hydration on the nickel-magnesia catalyst appear. The proportion of the nickel-alumina catalyst in the total catalyst volume can be 5 to 75%, so that the proportion of the nickel-magnesia catalyst Can occupy 95 to 25% by volume, the nickel-magnesia catalyst is expediently a proportion of 50 to 90, preferably from 75 to 90, for example 85% of the total volume of the catalyst, with the series connection according to the invention Niekel alumina catalyst and a nickel magnesia catalyst is used an increase in the service life of both catalysts to several operating

009828/0343 _ ₆ .

years achieved by each of the two catalysts below comparable conditions are not to be expected. The oxidation of a Hydrocarbon can e.g. B. run according to the following equations;

^C 6 ^H U + ■ ³ O ₂ = 6

6.5 O ₂ = 6COM H ₂ O Π

Part of the hydrocarbon can be mixed with water vapor and carbon dioxide react according to the following equations:

C ₀ H ₁ . t 6 H "O = 6 CO τ 13 H ₀ HI C ₆ H ₁₄ + 6 CO ₂ * 12 CO - 7 H ₂ IV

In addition, methane can also be formed according to the following equation:

2 CO + · 2 H ₂ * CH ₄ * CO ₂ V

The reactions I, II and V are exothermic, the reactions IH and IV proceed under heat consumption.

The reactions are largely simultaneous, but are individual Temperature ranges some of these reactions are preferred. Of the oxidation reactions mentioned, reaction II is preferred at lower temperatures expire. At high temperatures, decomposition according to equation I is favored.

009828/0343 _ ₇ _

Under otherwise identical operating conditions and based on the same With a nickel content, aluminum oxide catalysts are less hydrogenative than magnesite when splitting gaseous or liquid hydrocarbons Umoxide catalysts. This property is particularly troublesome at elevated reaction temperatures because, due to the higher temperatures Reaction speeds of the cleavage reactions, carbon is excreted, which is reflected in the system parts downstream of the cleavage reactor and can force the system to be shut down after a short period of operation.

Therefore, the alumina-supported catalysts require higher Reaction temperatures a higher steam supply for the reactions than catalysts with other carriers. Nickel-alumina catalysts, which can also contain an addition of chromium, are in a temperature * Range of up to 850 C can be used if the aim is not to completely split the gaseous or liquid hydrocarbons. Such catalysts are therefore suitable for cleavage conditions such as those at prevail on the inlet side 'of the reaction mixture in a catalyst bed. Such a catalyst lifts through a partial conversion of the oxygen after reactions I and II, the temperature of the reaction mixture above 600 ° C, e.g. B. 700 to 800 ° C, and at the same time splits part of the supplied hydrocarbons after reactions III and IV. The through

0 0 9 8 2 8/0343 ■ -r'i <i <ι ■■

the fission of the heat consumed is due to a further oxidation of Covered hydrocarbons, so that the oxygen concentration in the reaction mixture is reduced by a further partial amount. With With this reduced oxygen partial pressure and at an increased temperature of over 600 ° C., the reaction mixture enters the nickel-magnesia catalyst a. The endothermic and exothermic conversion of the remaining hydrocarbons takes place on this highly active catalyst Reaction of the remaining oxygen. Due to the simultaneous onset of stronger conversion of the hydrocarbons with water vapor And the oxygen consumption can cause a further increase in temperature of the reaction mixture take place, but the temperatures remain below about 1000 to 1150 ° C. It has proven to be useful for the purpose a high level of preheating of the input materials, especially for a part of the load of the system, over the first catalyst layer in a known manner

a 20 - 100 mm high inert material layer, such as. B. corundum to be arranged.

In the drawing is a reactor for carrying out the invention Procedure for example and shown schematically.

The expediently lined reactor vessel 1 contains on one layer Inert material 2, a layer 3 of a nickel-magnesia catalyst and a layer 4 of a nickel-alumina catalyst. This layer 4 can do that

0 0 9 8 2 8/0343

Complete the conical upper part of the boiler 1 or in a known manner a short piece can be poured into the feed line 5 for the preheated reaction mixture. Mostly, however, the conical upper part is with a layer 6 granular Iuertmaterials filled. The cracked gas leaves the Reactor 1 through the discharge line 7 and is used in this to the known processing and Storage facilities continued. The reactants, hydrocarbons, steam and oxygen, are in the feed line 5 introduced through connections 8 (steam), 9 (oxygen) and 10 (hydrocarbons) heated and received beforehand in the feed line 12 an addition of steam from the line 13. Optionally, the hydrocarbons can be combined cracked gas from the discharge line 7 can be admixed with or instead of steam.

The following examples may further illustrate the invention to serve:

example 1

The reaction vessel contains a nickel-magnesium catalyst with a Nickel content of 3%. Every 100 1 contact space is created by the line 10 65 kg / h gasoline in the boiling range 35 to 185 ° C and 83 kg / h water vapor, which are preheated to 450 ° C, introduced. Through the line 9 are the Reaction space also 46.3 Nm of oxygen per hour, with a purity

009828/0343

of 95% and fed through line 8 83 kg / h of steam.

This feedstock is converted into dry cracked gas of 260 Nm per hour produced with the following composition.

CO ₀ 16.55% by volume

CO 22.20 "

H ₂ 59.24 "

1.12 "

N "0.89"

The final reaction temperature is 900 ° C. The cracked gas is free of soot.

After a week's trial operation, the system had to be shut down because as a result of hydration of the catalyst support, the catalyst layer had collapsed by 180 mm and was in the catalyst space that had become free Pre-burns occurred.

Example 2

In the plant according to Example 1, the nickel-magnesium catalyst was replaced by a nickel-alumina catalyst with a nickel content of 3% by weight. For every 100 liters of contact space, 65 kg / h of gasoline in the boiling range from 35 to 185 ° C. and 107 kg / h of water vapor are introduced through line 10 into the contact space. ^{49.3 Nm 3 of} oxygen (purity 95%) and 107 kg / h of steam were introduced into the reactor every hour through line 1.

Q09828 / 0343

- 11 -

With a preheating of the water vapor and the gasoline vapor to a temperature of 450 C and a preheating temperature of the Oxygen to 100 ° C, 260 Nm dry cracked gas with approximately the same composition as in Example 1 are also generated per hour. The final reaction temperature is also 900 C.

Compared to example 1, 6, 5% more oxygen and approx. 29% more steam is used. If the addition of water vapor is reduced from 214 kg / h to 166 kg / h, the formation of soot begins forcing the system to shut down for a short time.

Example 3

The catalytic reaction space was filled with the following amounts of catalyst;

top layer: 1 liter of luert material

middle layer: 9 liters of aluminum oxide catalyst

Bottom layer: 90 liters of magnesium oxide catalyst

The same starting materials were used in the same in the reaction chamber Amount introduced as in Example 1. The generated gas also had the same composition.

- 12 -

009828 / 03A3

After several months of trouble-free operation, the system was shut down to test the catalytic converter. It turned out that that Contact bed had not sunk and that hydration of the magnesia catalyst had not occurred either.

- 13 claims

009823/0343

Claims (6)

Patent claims , 1) Process for the flameless conversion of gaseous or liquid hydrocarbons or gases containing them on fixed catalysts with to the vollstviidi ^ Incineration does not contain sufficient amounts of oxygen, oxygen-enriched air or air, and possibly Steam and / or carbon dioxide, the substances to be converted before or during their introduction into the reaction furnace are brought together, characterized in that the hydrocarbons and the free oxygen containing gases, possibly together with water vapor, preheated separately in a manner known per se to temperatures at which the mixture can be ignitable, then merged and durclykatalysatorbett is performed, which in the upper layer a Niolei.-alumina catalyst and in the lower layer a nickel magneea catalyst contains. 2) Method according to claim 1, characterized in that the catalyst on aluminum oxide as a carrier fills 5 to 75 $, preferably 10 to 25 -i °, of the total catalyst volume. -H- 009828/0343 3) Method according to claim. 1 and 2, d-marked by -eken ... because: the grain size of the catalysts is 6 to 30 inches, vorzu ₍ jsv / otherwise 12 to 18 mm. 4) Method according to claim 1 to 3 »characterized in that that the working pressure is 1 to 50 ata, preferably 20 to 30 ata. 5) Method according to claim 1 to 4, characterized in that ^ «indicates that daL the catalysts contain chromium and tungsten additives. 6) Procedure according to outbreak 1 to 5, d-by ^ oker.:. Draws, that the Aluminiunox, / ·.! .. analyzer has an inert layer of 20 "to 100 mm in height connected upstream. BATH 009823/0343