DE1233089B - Process for the production of methane-containing gases - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

Clog

German KL: 26 a -12

Number: 1 233 089

File number: G 35255IV d / 26 a

Filing date: June 20, 1962

Opened on: January 26, 1967

The invention relates to the production of methane-containing gases from mixtures of predominantly paraffinic hydrocarbons with an average of at least 4 carbon atoms and represents a further development of the process described in British patent 820 257. In this known process, the vapors of the hydrocarbons and water vapor are under normal pressure or overpressure passed through a bed of a nickel catalyst, and these vapors and the water vapor are inserted in such an above 350 ⁰ C temperature lying in the catalyst bed, that the bed is maintained by the reaction at a temperature in the range of 400 to 550 ° C.

In addition to this well-known process, the so-called "reforming" reaction is known at which is a mixture of light hydrocarbons and water vapor in the presence of nickel catalysts is implemented at temperatures of about 900 ° C. The resulting product gas consists of the essentially from a mixture of carbon monoxide and hydrogen. This gas mixture has a comparatively low calorific value, so that it is enriched with a gas with a higher calorific value or a renewed reaction over nickel catalysts in a second reaction stage, with lower Temperatures, which are approximately in the range of 250 to 500 ° C, is required to produce a gas with the desired To maintain calorific value.

It is also already known that diesel oil or kerosene is converted into oil gas with steam at lower temperatures, namely at temperatures in the range from about 700 to 900 ^° C., in the presence of nickel catalysts. In this known oil gas production, it is not easy to carry out an economically satisfactory process for producing heating gases with a high calorific value. The efficiency of such a process is unfavorable because a large amount of carbon, tar and the like accumulates at the same time as the combustible gases and strong carbon deposits on the catalyst and even penetration of carbon into the catalyst can take place, which quickly becomes ineffective. In order to overcome these difficulties, a process of this type has become known, which is carried out as a cycle process and in which the vaporized hydrocarbon and hydrogen are passed through a catalyst zone, which has a temperature gradient not exceeding 55 ° C, and nickel during the gas generation part of the cycle process -Process for the production of methane-containing
Gases

Applicant:

The Gas Council, London

Representative:

Dr.-Ing. A. v. Kreisler, Dr.-Ing. K. Schönwald,

Dr.-Ing. Th. Meyer and Dr. J. F. Fues,

Patent attorneys, Cologne 1, Deichmannhaus

Named as inventor:

T. A. Yarwood, Olton, Solihull; *

G. Percival,

Solihull, Warwickshire (UK)

Claimed priority:

Great Britain June 21, 1961 (22 488)

containing refractory bodies, the mass of which is between about 4.7 and 50 kg / m ² surface, and which have a nickel concentration in the outer 0.8 mm of the surface between about 0.07 and 0.15 kg / m ² surface, and wherein a certain hydrocarbon feed is used in relation to the catalyst surface area and the gas flow consisting of the hydrocarbon and water vapor is interrupted before the temperature of the catalyst zone drops by appreciably more than 55 ° C. In this known method, the disadvantage of the strong coking of the catalyst is countered by means of procedural measures that must be precisely adhered to within narrow limits. However, since it can easily happen in practice that such precise reaction conditions are not always reliably observed, the fact that the catalyst is coking remains as an undesirable side effect.

In the present process, as well as in out British Patent 820,257 known method is the risk of coking of the catalyst thereby completely avoided, that lowers the temperature of the catalyst bed to the range of 400 to 55O ⁰ C. At this low reaction temperature, a superposition of different reaction types takes place at the same time. On the one hand, a reforming reaction creates a combustible gas mixture, on the other hand it takes place in this

609 759/165

3 4

Methane formation temperature range. Since the reforms is introduced that the bed mierungsreaktion by the reaction is an endothermic reaction, but which is exothermic at a temperature in the range of 400 to 55O ⁰ C methane formation, it is possible is maintained in good yield methane-containing, by suitably heating of the starting mixture , can produce gases thereby when in the hold, the reaction of the catalyst bed always in the 5 mixture existing paraffinic hydrocarbon-range of 400 to 55O ⁰ C and premature fabrics with an average of 4 to 15 carbon atoms thermal decomposition of the hydrocarbons begins to comparable and avoid the mixture of hydrocarbons. In this known method, the vapor and the water vapor with a linear pressure can be up to 50 atmospheres and a given speed of 0.18 to 5.5 m / min, and one if also higher. Expedient are pressures in the room flow velocity of at least the range from 10 to 25 atmospheres. 400 V / V / hour leads through the catalyst bed.

In order to avoid carbon buildup on the catalyst, it is advantageous to work at a pressure in the range where the water vapor content is in the ratio of 10 to 25 atmospheres. It is advisable to add a water vapor amount of 2 to 5 reacting amounts to the hydrocarbons above the actual amount. The water vapor excess required for this purpose per part by weight of hydrocarbon mixture depends on the average and leads to the mixture of vaporous molecular weights of the hydrocarbons used, hydrocarbons and water vapor, in parallel and increases with increasing molecular weight. a variety of catalyst beds.
However, the excess is not high. When using a catalyst bed which has hydrocarbon mixtures with an average of 4 to 20 elongated tubular shapes, it is advantageous that the 10 carbon atoms can introduce 2 parts by weight of water hydrocarbon vapors and the water vapor in vapor per part by weight of hydrocarbons used to introduce the inner periphery of the bed and the will. A higher amount of water vapor to gaseous reaction products from the outer to 5 parts by weight per part by weight of hydrocarbon periphery of the bed can be considered, and with hydrocarbon 25 or one works in this device so that the mixtures with an average of 4 to 7 Carbon- hydrocarbon vapors and the water vapor in hydrogen atoms can be lowered by as much as 1.5 parts by weight being introduced to the outer periphery of the bed. _ and the gaseous reaction products from the

The methane content of the gas formed is the higher the bed withdrawn from its inner periphery, the lower the temperature of the catalyst and the higher the pressure. The gas formed can be prolonged if the nickel-aluminum oxide is contained after the removal of the carbon dioxide and a catalyst having a particle size in the range of and water vapor is generally used at least 50 vol. 150 to 1000 microns. Such a nickel lum percentage methane. At relatively higher pressure, the aluminum oxide catalyst can expediently be used, for example at 50 atmospheres, the methane concentration of metallic nickel can exceed 75 ° / ₀ and the tration can exceed 80 ° / ₀ . of not more than 90 ° / ₀ , based on the total

The catalyst used is preferably a coarse weight of nickel and aluminum oxide, part, for example granulated or pelletized The expression »linear velocity nickel-aluminum catalyst, The “common” denotes a rate that is calculated for the same precipitation of nickel and aluminum compounds by measuring the volume of the per unit of time fertilize by treating an aqueous mixture and volume entering the bed Solution of water-soluble salts, for example that of the gemi-nitrate emerging from the bed per unit of time, of nickel and aluminum with a cal correction of the volumes to take into account Alkali compound, e.g. B. Sodium carbonate and Re- the temperature difference between inlet and Reduction of the nickel compound in the precipitation to an outlet mixture, averaging of these volumes and the metallic elements Nickel has been produced. calculation of the linear velocity from the mean

With this volume, which is larger from British patent specification 820 257 (the one containing the catalyst

known method is also the post-treatment vessel is assumed to be empty),

of the methane-containing gas formed in the presence The average carbon number of the here in

a nickel catalyst described. 50 question is coming hydrocarbon mixtures

It has now been found that the life is determined by determining the average of the catalyst, which in the known method is limited molecular weight of the mixture of coals, presumably by waste hydrogens by measuring the reduction in freezing storage of polymerization products to the point of pure Benzene, which is caused when the catalyst and from mixtures of predominantly 55 a certain amount of the mixture is dissolved in paraffinic hydrocarbons with average, and determination of the number of carbon overflows of a mixture of vapors of the at least 4 hydrocarbon atoms due to borrowed hydrocarbon molecules Carbon atoms by powder chromatographic analysis Hydrogen with water vapor at normal pressure or for the purpose of determining the proportions by volume of the paraffinic, olefinic and aluminum oxides present in the excess pressure over a bed of particles of a mixture of nickel yd catalyst made by common aromatic hydrocarbons.
Precipitation and subsequent reduction of the nickel an improvement of the process of the British compound to metallic nickel has been produced in patent specification 820 257 is that a nickel is and the optionally an addition of an oxide, aluminum oxide catalyst of the above-described hydroxide or carbonate of an alkali or Earth-level type is used, which, however, contains an additive alkali metals, the mixture of carbons containing an oxide, hydroxide or carbonate of an alkali hydrogen vapor and water vapor in the case of such or alkaline earth metal or magnesium. The temperature in the bed is above 35O ⁰ C. It is particularly advantageous to add potassium

carbonate. The addition of such an alkali compound extends the life of the Catalyst. The method according to the invention can with such a catalyst or with a Nickel-aluminum oxide catalyst which does not contain the addition of an alkali compound will.

To with the method according to the invention despite the relatively low linear speed of the gaseous mixture flowing through the catalyst bed generates a high level of methane-containing To achieve gas at a given space flow rate, it is usually expedient to use the Volume of the gaseous mixture treated per unit of time by increasing the cross-sectional area of the bed through which the gaseous mixture is passed. For this purpose, the catalyst bed the form of a multitude of layers are given through which the gaseous mixture is guided in parallel. It is also possible to use a catalyst bed in the form of an elongated tube, by which the gaseous mixture in the radial direction from the inner periphery of the bed to the outer Periphery or in the opposite direction. If necessary, several of these can be tubular Beds are used through which the gaseous mixture is passed in parallel.

Examples of ways to achieve a high production of methane-containing gas will be described below with reference to the drawing.

F i g. 1 is a longitudinal section through a pressure vessel in which a multiplicity of catalyst beds are arranged is through which the gaseous mixture is passed in parallel;

F i g. 2 is a longitudinal section through a pressure vessel containing a catalyst bed of tubular shape; by which the gaseous mixture in the radial direction from the inside to the outside of the bed is directed.

The in Fig. 1 illustrated pressure vessel 1 is provided with a centrally arranged tube 2 which is open at the top and closed at the bottom and is surrounded by a housing or jacket 3. Between the Outside of the tube 2 and the inside of the side wall of the shell 3 are a plurality of catalyst units 4 arranged. Each of these catalyst units consists of a perforated base 5 and a partition 6 located above and a partition 7 below it. The partition walls are connected to the tube 2 and the jacket 3 in a gas-tight manner. In the uppermost catalyst unit 4 forms the partition 6 the upper end of the jacket 3. Each base 5 serves as a base for a catalyst layer 8 of suitable height.

The preheated mixture of hydrocarbon vapors and water vapor enters tube 2 at 9 introduced and divided into parallel streams passing through openings 10 in the tube 2 in the spaces above of the catalyst arrive in units 4. Each gas stream flows down through a catalyst bed into the space under this bed and enters an annular space 12 through openings 11 in the jacket 3 from where the streams unite and finally leave the pressure vessel through outlet 13. the Partitions 6 and 7 ensure that the gas takes the prescribed route. Instead of two Providing partition walls between two adjacent units 4 can be a single partition can be used, which serves as both an upper and a lower partition.

As an alternative, the tube 2 can be open at the bottom and

be closed at the top so that the mixture of hydrocarbon vapors and water vapor below is inserted into the pipe. The product gases can exit the pressure vessel at the top or bottom.

The in Fig. 2 illustrated pressure vessel 20 is provided with a centrally arranged catalyst chamber 21, which is formed by two coaxial, perforated, tubular components 22 and 23, which are cylindrical or can be frustoconical. The inner component 22 is at the top with a gas inlet 24 at the top of the pressure vessel in connection and is closed at the bottom. The one through the Parts 22 and 23 limited annular space 25 is closed at the top and bottom, so that the gas is forced to the To flow through the annular space radially outwards. The pressure vessel 20 is at the lower end with a gas outlet 26 provided.

Annular space 25 is filled with catalyst and the preheated mixture of hydrocarbon vapors and water vapor is introduced through inlet 24. The mixture flows through the catalyst bed radially outwards into an outer annular space 27 within the pressure vessel and leaves this through the outlet 26. The pressure vessel can be upright, as in FIG. 2 shown, or lying or be arranged in any other suitable position.

If necessary, the pressure vessel can be turned upside down, with the gas mixture moving upwards in flows through the inner cylinder 22 and the device leaves the outlet 26, which is now at the Top of the pressure vessel. It is also possible to use the preheated mixture of hydrocarbon vapors and to supply water vapor to the outer annular space 27 and the products out of the withdraw the central tube 22 through the opening 24, but this is less advantageous.

It has also been found that in the process according to the invention it is advantageous to use the catalyst to be used in the form of particles with a size in the range from 150 to 1000 μ. These particles are substantial smaller than the particles commonly used at conventional linear velocities (e.g. particles from 6.4 to 3.2 mm at linear velocities of 0.3 to 0.6 m / sec. [18.3 to 36.6 m / min.]). The use of catalyst particles of the above small size affects so that compared to using larger particles at speeds of not more than 5.5 m / min, and at the usual high speeds the life of the catalyst is extended, recognizable by the period between the first introduction of the hydrocarbon-water vapor mixture into the catalyst bed and the point in time at which undecomposed hydrocarbon was first discovered in the exiting gases will.

The proportion of metallic nickel in the catalyst is preferably in the range of 28 to 75 ° / _0, based on the total weight of metallic nickel, and aluminum oxide. Nickel-aluminum oxide catalysts, the nickel content of which is above 75% (calculated on the basis mentioned above), have a somewhat lower mechanical strength, so that at the usual linear speeds there is a risk of the particles and dust falling apart.

formation and consequently an increase in the resistance of the bed to the flow of gases consists. This does not only apply to the nickel-aluminum catalysts, which have an addition of an alkali compound included, but also for nickel-aluminum oxide catalysts without this addition.

It proved to be advantageous in the process according to use of the invention, nickel-alumina catalysts which have been prepared in the manner mentioned by coprecipitation and subsequent reduction of the nickel compound and metallic nickel is not used in an amount of more than 75 ° / ₀ and contain more than 90 ° / ₀ , based on the total weight of nickel and aluminum oxide. These catalysts can optionally contain an alkali compound as an additive. The nickel content is preferably in the range of 80 to 85 ° / ₀ calculated on the aforementioned basis.

The increase in the nickel content can be expected to extend the life of the catalyst, however, it has been found that the process according to the invention increases the life of the Catalyst is larger than was foreseen from the increase in the nickel content. Catalysts with The above-mentioned higher nickel contents also have the advantage that the costs of recovery of nickel from these catalysts after replacement or for other reasons than with catalysts with a lower nickel content.

example 1

Experiments are described, which the influence of a decrease in the linear speed according to the Illustrate the invention. A granulated nickel-alumina catalyst was used in these experiments used, which had been produced without the addition of potassium carbonate. The catalyst had the following composition:

vapor mixture up to the point in time at which non-decomposed hydrocarbon was first discovered in the outlet gases, it was found that the emerging gases did not contain any undecomposed hydrocarbon after about 2500 hours. The attempt was then canceled. During the experiment, a hot reaction zone about 6.4 mm thick and with a temperature of about 480 ^° C. migrated upward through the bed. If canceled

ίο of the experiment this reaction zone had a little less than covered half the way up through the bed. From this it was evident that it was possible would be to continue the attempt for almost the same amount of time.

The experiment described above was carried out with the same distillate and with the same catalyst repeated under the same conditions, but this time the height of the catalyst bed was 30.5 cm, the linear speed 30.2 m / min.

and the space velocity 44,000 V / V / hr. Undecomposed hydrocarbon was in the escaping gases were first discovered after a period of 20 hours. This attempt is due to the large difference between the applied Ra to flow velocities is not actually involved comparable to the previous experiment, but it can be assumed without further ado that in the event of a lowering the space flow velocity in the experiment described last to 4000 by enlarging it the height of the catalyst layer to 3.35 m undecomposed hydrocarbon for the first time after a while would have occurred for no more than 220 hours.

Example 2

Ni.

Parts by weight. . 75

Al ₂ O ₃ 25

K <0.02

Na <0.01

Ca <0.003

Fe <0.001

SO ₁ <0

The granulated catalyst was sieved to particle sizes from 500 to 850 μ.

Was used a light petroleum distillate having an average carbon number of 5.8, a boiling point between 40 ° to 97 ° C and a specific gravity of 0.67 at 20 ⁰ C. A mixture of 1 part by weight of the distillate in vapor form and 2 parts by weight of water vapor was on 450 ⁰ C preheated and passed under a pressure of 25 atmospheres through a bed of the above-mentioned catalyst, which had a height of 15.2 cm. The mixture flowed through the bed at a space velocity of 4000 V / V / hr. and a linear speed of 1.4 m / minute.

In an attempt to determine the life of the catalyst, i. H. the period from the initial Introduction of the hydrocarbon-water There were three experiments A, B and C with one

Nickel-aluminum oxide catalyst carried out, which was produced with the addition of potassium carbonate and had the following weight composition:

Ni 75

Al ₂ O ₃ 25

K (added as K ₂ CO ₃ ) 1.65

Na 0.01

Ca 0.003

Fe 0.003

SO ₄ 0

The fractions mentioned below were sieved out of the granulated catalyst.

In each experiment, a petroleum distillate having an average carbon number of 6.1, a boiling range of 26-140 ⁰ C and a specific gravity of 0.68 at 20 ° C was used. A mixture of 1 part by weight of the distillate in vapor form and 2 parts by weight of water vapor was preheated to 450 ⁰ C and under a pressure of 25.5 kg / cm ² down through a bed of the catalyst. In experiments A and B, the catalyst bed had a height of 15.2 cm and in experiment C a height of 30.5 cm. The linear velocities and the space flow velocities in V / V / hour. are given below. The following results were obtained:

9 Size range
of the granulated catalyst 10 Room flow
speed First appearance
of not decomposed
Hydrocarbon Linear
speed 500 to 850 μ
3.2 to 6.4 mm
500 to 850 μ 8000 V / V / h
8000 V / V / h
44000 V / V / h after 1850 hours
after 385 hours
after 260 hours A.
B.
C. 2.75 m / min.
2.75 m / min.
30.2 m / min.

Example 3

Experiments were carried out using a nickel-alumina catalyst of the composition given in Example 2 and the particle size ranges given below. Was used a petroleum distillate having an average carbon number of 6.1, a boiling range of 26 to 14O ⁰ C and a specific gravity of 0.68 at 20 ° C at a space velocity of 8000 V / V / hr. and the linear velocity given below. In both experiments, a mixture of 1 part by weight of the distillate in vapor form and 2 parts by weight of steam was preheated to 450 ° C. and passed through a 15.2 cm high bed of the catalyst ^{under a pressure of 25.5 kg / cm 2.} The service life was assumed to be the time from the first introduction of the hydrocarbon-water vapor mixture to the first appearance of undecomposed hydrocarbons in the gases emerging from the catalyst bed. The following results were obtained:

Linear
speed

2.75 m / min.
2.75 m / min.

: Size range

of the granulated

Catalyst

'' 500 to 850 μ
210 to 440 µ

First appearance

of not decomposed

Hydrocarbon

after 1850 hours
after 3000 hours

Example 4

Experiments are described with which the influence of the use of a nickel-aluminum oxide catalyst with a. Nickel content of more than 75 ° / ₀ (based on the total weight of nickel and aluminum oxide) as compared to using a catalyst having a nickel content of 75 ° / o is determined. The catalysts were produced with the addition of potassium carbonate and had the following composition by weight:

catalyst Ni Al ₂ O ₃ K
(added as
K ₂ CO ₃ ) N / A- Approx Fe SO ₄ A.
B. 75 "
82.2 25th
17.8 1.65
1.1 0.01
0.01 0.003
0.003 0.003
0.003 0
0

The fraction from 500 to 850 μ in each case was sieved out of the granulated catalyst and used.

A petroleum distillate with a boiling range from 26 to 140 ° C., as described in Example 3, was used. In each experiment, a mixture of 1 part by weight of the distillate in vapor form and 2 parts by weight of steam was preheated to 450 ° C. and under a pressure of 25.5 kg / cm ² at a linear velocity of 2.7 m / min, and a space flow velocity of 8000 V / V / h passed through a bed of catalyst A and B, respectively. The following results were obtained:

55

Example5

Experiments are described which examine the influence of a decrease in the linear velocity on the life

catalyst First appearance
of not decomposed
Hydrocarbon A.
B. after 1850 hours
after 2750 hours

duration of the catalyst in the treatment of mixtures of hydrocarbons of higher average Carbon number as the hydrocarbons used in the process of British Patent 820,257 illustrate.

Two experiments A and B were carried out using a _{catalyst containing potassium (added as K 2} CO ₃ ) and having the composition mentioned in Example 2. The sieve fractions of the granulated catalyst mentioned in the table below were used.

A petroleum distillate with an average carbon number of 11.5, a boiling range of 120 to 280 ° C. and a specific gravity of 0.79 at 20 ° C. was used in each experiment. A mixture of 1 part by weight of the distillate in vapor form and 2 parts by weight of steam was preheated to 450 ° C. and passed through a bed of the catalyst from top to bottom ^{under a pressure of 25.5 kg / cm 2.} In experiment A the catalyst bed had a height of 15.2 cm and in experiment B a height of 30.5 cm. The linear velocities and the space flow velocities in V / V / hour. are listed below along with the results.

Linear
speed Sieve fraction of the catalyst Room flow
speed First appearance
of not decomposed
Hydrocarbon A.
B. 2.75 m / min.
30.2 m / min. 500 to 850 μ
500 to 850 μ 8000
44000 after 768 hours
after 96 hours

609 759/165

It is true that there is a difference between the space flow velocities used in experiments A and B. large, but it can be assumed without further ado that with a decrease in the space flow velocity in experiment B on for the first time by increasing the height of the catalyst bed to 1.7 m non-decomposed hydrocarbon would be detected after a period not exceeding 528 hours.

Claims (5)

Claims: IO 1. A process for the production of methane-containing gases from mixtures of predominantly paraffinic hydrocarbons with an average of at least 4 carbon atoms by passing a mixture of the vapors of the hydrocarbon mixture with water vapor at normal pressure or overpressure over a bed of particles of a nickel-aluminum oxide catalyst, which is precipitated together and subsequent reduction of the nickel compound to metallic nickel has been produced and which optionally contains an addition of an oxide, hydroxide or carbonate of an alkali or alkaline earth metal, the mixture of hydrocarbon vapors and water vapor being introduced into the bed at a temperature above 350 ° C, that the bed is kept by the reaction at a temperature in the range from 400 to 550 ° C, characterized in that a mixture of paraffinic ι hydrocarbons with an average of 4 to ^; 15 carbon atoms are used and the mixture of hydrocarbon vapors and water vapor at a linear velocity of 0.18 to 5.5 m / min, and a space flow velocity of at least 400 V / V / hour. by the catalyst bed is passed. 2. The method according to claim 1, characterized in that the mixture of vaporous Hydrocarbons and water vapor introduced in parallel into a plurality of catalyst beds will. 3. The method according to claim 1, characterized in that the hydrocarbon vapors and the water vapor into the inner periphery of the catalyst bed set up in an elongated tubular shape are introduced and the gaseous reaction products enter the bed from the outside Leave the periphery of the bed or that the hydrocarbon vapors and the water vapor are introduced into the outer periphery of the bed and the gaseous reaction products leave the bed from its inner periphery. 4. The method according to claim 1 to 3, characterized in that a nickel-aluminum oxide catalyst is used in a particle size in the range of 150 to 1000 microns. 5. The method of claim 1 to 4, characterized in that a nickel-alumina catalyst having a proportion of metallic nickel of more than 75 ° / ₀ and of not more than 90 _^0/0, based on the total weight of nickel and aluminum oxide , is used. Considered publications:
German interpretative document No. 1 026 472. 1 sheet of drawings 609 759/165 1.67 © Bundesdruckerei Berlin