DE2230916A1 - PROCESS FOR REFORMING HYDROCARBONS - Google Patents

Description

L j 23. JÜKI-197Z

Process for reforming hydrocarbons

The invention relates to a method for the steam reforming of hydrocarbons, in particular a method for the extraction of methane-containing gases by steam reforming different batches in a single combined reaction system.

It is already known, for example from British Patent Specification 820 257, to obtain a methane-containing gas by steam reforming of a mixture of predominantly paraffinic hydrocarbons, such as butane, light naphtha and the like, and steam at a temperature of 400 to 500 ⁰ C in the presence of a nickel-containing catalyst. In the steam reforming of high-average molecular weight hydrocarbons, however, it is difficult to maintain the catalytic activity of the catalyst over a long period of time in order to ensure smooth operation of the reforming device due to the tendency of carbonaceous material to deposit on the speckled steam reforming catalyst . In order to counter these difficulties, in particular in order to reduce the impairment of the catalytic activity of the catalyst to a minimum, it is customary to work with an excess of steam.

0083/1030

The use of a steam over shot is not, however only uneconomical with regard to the production costs of the required device and from a thermal point of view, In addition, it does not always lead to an ideally composed gaseous end product. The latter it follows without further ado that the steam reform

en

mation reaction of hydrocarbons by the most diverse chemical equilibrium formulas can be reproduced.

To solve these problems, according to the teachings of the Japanese Patent application 22 413/1969 already tried a Hydrocarbon mixture distributed the reaction zones of two or to feed several catalyst beds and the total amount of steam into the reaction column of the first reaction stage to feed. In this way, the ratio of steam to the mixture of hydrocarbons in the respective reaction zones should be increased.

Finally, it is also known from British patent specification 1,053,855 to increase the service life or the catalytic Activity of a catalyst over a long period of time instead of excess vapor hydrogen in the reaction system to introduce. In accordance with the teachings of this reference, the hydrogen source can be obtained directly from a high temperature reforming device and the like escaping gas are used.

The invention was now based on the object of providing a method for reforming hydrocarbons, in particular for the production of eLnes methane-containing gas to create the The known processes described are superior to Lst, and Ls in particular eLne effective and smooth steam ref ormierurii'pe Lbs t comparatively heavy hydrocarbons permitted.

2 0Π 803/1030

BAD ORSQlNAt

The invention thus provides a process for reforming hydrocarbons containing at least two carbon atoms per molecule in at least two stages and in the presence of a nickel-containing catalyst, which is characterized in that in the reaction zone of a first reaction stage in the presence of a nickel-containing catalyst at a temperature of 350 ° to 550 ⁰ C adiabatic steam reforming performs a hydrocarbon fraction with a relatively low average molecular weight, are admixed to each carbon atom of this hydrocarbon fraction from 1.0 to 5.0 mol (e) steam, and in that subsequently in the reaction zone at least one further reaction stage in the presence of a nickel-containing catalyst at a temperature of 500 ° to 550 ⁰ C adiabatic steam reforming of a hydrocarbon mixture consisting of the gaseous reaction product from the first reaction stage and a Reaktionszoneder Kohlenwasserstof part with a relatively high average molecular weight, using the ratio of steam to hydrocarbon content. with a larger average molecular weight selects less than the ratio of steam to hydrocarbon content maintained in the first reaction zone (with a lower average molecular weight).

In the second stage of the process according to the invention, fresh steam can optionally be fed in.

The attached drawing shows a graphic representation the relationship between the temperature and length of the catalyst bed during steam reforming of naphtha.

Hydrocarbons reformable by the process according to the invention For example, those with two or more carbon atoms per molecule are petroleum refinery gas, moist

-4-209R8 3 / 103Q

-4- 223Q916

Natural gas, liquefied natural gas, light naphtha, heavy naphtha, Kerosene and the like. Which hydrocarbons in the reaction zone of the first reaction stage and which hydrocarbons are treated in the reaction zone of the second reaction stage, is decided according to their middle Molecular weight. The average molecular weight to be treated in the reaction zone of the second reaction stage Hydrocarbons must be greater than that of the hydrocarbons to be treated in the reaction zone of the first reaction stage. For example, butane is used in the reaction zone treated in the first reaction stage and naphtha in the reaction zone in the second reaction stage. Light naphtha is in the reaction zone of the first reaction stage and heavy naphtha in the reaction zone of the second reaction stage treated. The fraction obtained by fractionating a hydrocarbon mixture into light and heavy fractions is in the reaction zone «of the first reaction stage, the heavy fraction obtained in this way in the reaction zone of the treated second reaction stage. This means that the hydrocarbons to be treated in the reaction zones of the first and second reaction stages are easily more suitable Let wise choose.

In the reaction zone of the first reaction stage - at low temperature - the steam reforming of hydrocarbons with comparatively low or low molecular weight takes place adiabatically with a molar ratio of steam to fed hydrocarbons in the range from 1.0 to 5.0 mol (s) per 1 carbon atom at a temperature at the inlet of the reaction zone of from 550 ° to 55O ⁰ C and a pressure of 0 to 100 kg / cm G, and using a nickel-containing catalyst. Suitable nickel-containing catalysts are all catalysts customary for the steam reforming reaction at low temperature, for example nickel

+ light

? 0 9 Π R 3/1 0 3 0

one component and other components, e.g. metals of group VIII, metals of the left column of group VII, Metals of the left column of group VI, metals of group II or metals of the right column of group I of the periodic table, Alkali metals and the like. As active ingredients or auxiliary ingredients containing catalysts and the Catalysts containing the constituents described in combination with customary known promoters and / or carriers; The gaseous product emerging from the reaction zone of the first reaction stage consists of a methane, hydrogen, Gas mixture containing carbon monoxide, carbon dioxide and unreacted vapor.

The gaseous product emerging from the reaction zone of the first reaction stage as part of the process according to the invention is then in the reaction zone of a second reaction stage, optionally after the addition of fresh steam and after the addition of other hydrocarbons, the average molecular weight of which is higher than the average molecular weight of the Reaction zone of the first reaction stage treated hydrocarbons, at an inlet temperature of 500 ° to 550 ⁰ C, and a suitably selected pressure, preferably under a pressure of 0 to 100 kg / cm G, and subjected to steam reforming in the presence of a nickel-containing catalyst. The nickel-containing catalysts which can be used in the second reaction stage of the process according to the invention can be the same nickel-containing catalysts as are also used in the first reaction stage of the process according to the invention.

Although the steam reforming reaction in the reaction zone ± b the second reaction stage on relatively heavy hydrocarbons is carried out, is prolonged - since this steam reforming co-action in the presence of the reaction

-6-209R83 / 1030

zone of the first reaction stage originating gaseous methane, The product containing hydrogen, carbon dioxide and the like will expire - the life of the catalyst entirely considerable, which in turn, in contrast to the usual known steam reforming processes for hydrocarbons reduced steam ratio enables a smooth reaction process. In this context it should be pointed out that that the quantitative ratio of hydrocarbons to be treated in the reaction zone of the first reaction stage to in the reaction zone of the second reaction stage to be treated hydrocarbons can easily be determined in a suitable manner.

According to the method according to the invention, even batches such as heavy naphtha, kerosene and the like, their Use for the production of methane-containing gases by gasification was previously uneconomical from an economic point of view was held to treat appropriately, suggesting the combination of these batches with hydrocarbons lower average molecular weight (than their own molecular weight). In the case of the invention carried out steam reforming of hydrocarbons, the significantly reduced steam addition has an increase in the Methane content in the gaseous reaction product result. Consequently, the gaseous end product which can be obtained by the process according to the invention is highly suitable V / eise for use as town or heating gas.

In the context of the method according to the invention, the water-containing agent that allows the steam supply to be reduced is used Gas to extend the life of the steam reforming catalyst from the one approved in the same reaction system hydrogen-containing ^ gas supplied. In addition, bt i the steam reforming of the comparatively difficult, η coal

2 0 9 Π R 3/1 Ο 3 0

Hydrogen from steam reforming is relatively lighter Hydrogen-containing gas derived from hydrocarbons at low temperature instead of one in a high temperature reforming device (See, for example, British patent specification 1,053,855) formed hydrogen-containing gas used. The effect of the use of the steam reforming reaction The gaseous product formed at a low temperature can be identified by comparing the following of the present invention Understand the examples carried out with the comparative examples carried out in a different way.

To carry out the method according to the invention it is readily possible to have a plurality of reaction zones, e.g., a first reaction zone, a second reaction zone, a third reaction zone, etc. to connect to one another to produce the middle in the production of the desired methane-containing gas Molecular weight in the various reaction. zones to be treated hydrocarbons.

The following examples are intended to explain the method according to the invention in more detail.

example 1

For comparison purposes, various tests were carried out in the present case. As the starting hydrocarbon feedstock is a naphtha per molecule has an average of 7 * 0 carbon atoms, an IBP of 40 ° C, a PBP of 185 ⁰ C and a specific gravity (d ¹ 5) _of 0.7 and using butane.

Test 1

When one with steam in the ratio 2.0 moles of steam per 1 carbon atom the naphtha charge mixed naphtha charge in a nickel-containing catalyst with Kieseiguhr as a carrier

-8th-

packed, adiabatic reactor at an inlet temperature of 50O ⁰ C and a pressure of 33 kg / cm O with a mass ^{velocity of 20,000 kg / m 2} h, the outlet temperature rose to 5JO ⁰ C. On this occasion it should be noted that that the temperature distribution in the catalyst bed of the adiabatic reactor changed in the course of the experiment, as can also be seen from the graphic representation of the drawing. (The solid line A shows the distribution state after θ std after the start of the experiment; the dashed line B shows the distribution state B + Δ Ο std ^! After the start of the experiment) This indicates that the catalyst activity decreased gradually, which resulted in the termination far more catalyst was required to react and to achieve equilibrium. It is possible on this occasion to determine the amount of catalyst required to complete the reaction by measuring the temperature distribution. In this way, the amount of catalyst required to complete the reaction was estimated. Furthermore, the composition of the gaseous end product obtained was analyzed.

Test 2

If the steam in a ratio of 5.0 moles of steam per 1 carbon atom of the butane batch mixed butane feedstock in an adiabatically operating reactor of the first reaction stage, which was packed with the same nickel-containing catalyst such as in an attempt at an inlet temperature of 544 ⁰ C and a pressure of 33 kg / cm ² G to a ground speed of 20, 000 kg / m ² std fed, the outlet temperature dropped to 500 ⁰ C.

-9-209883 / 1030

If the gas from the first reaction stage, containing undecomposed vapor, was mixed with the naphtha charge and the mixture obtained, after the addition of fresh steam in the ratio of 1.5 moles of total steam per 1 carbon atom of the naphtha charge, an adiabatic reactor of the second reaction stage, which with the same · nickel-containing catalyst was packed in einer'Einlaßtemperatur of 435 ° C and a pressure of "33 kg / cm ² G ⁺ supplied, so the outlet temperature rose to 530 ⁰ C. In the same manner as in experiment 1, the amount of to complete the reaction after 500 hours of required catalyst and the composition of the gaseous end product is determined In this connection, it should be noted that the weight ratio of the butane to be treated in the first reaction stage to the naphtha to be treated in the second reaction stage is 1.0: 3.43 fraud.

Test 3

If the hydrocarbon charge consisting of butane and naphtha in a weight ratio of 1: 3 * 43 is mixed with steam in the ratio 1.8 moles of steam per each carbon atom contained in the hydrocarbon charge and the mixture obtained is an adiabatic reactor packed with the same nickel-containing catalyst as in experiment 1 was fed in at an inlet temperature of 495 ⁰ G and a pressure of 33 kg / cm G and a mass velocity of 20,000 kg / m std, the outlet temperature rose to 530 ⁰ C. In the manner described in experiment 1, the amount of the to terminate the implementation after 500 hours of required catalyst and the composition of the gaseous end product is determined.

Test 4

The one with steam in the ratio 5 * 0 moles of steam per 1 carbon atom The butane batch of mixed butane became adiabatic

+ with a mass velocity v. 2o 000 kü / m std

-10-209883 / 1030

working reactor of the first reaction stage, which is equipped with a nickel-containing catalyst for high temperature reforming, was packed at a temperature of 400 ° C and a pressure

of 33 kg / cm G were fed in, the outlet temperature rising to 80O ⁰ C.

The gaseous product was mixed together with unreacted steam from the first reaction stage with the naphtha charge and fresh steam in a ratio of 1.5 moles of total steam per 1 carbon atom of the naphtha charge and the mixture obtained was mixed in an adiabatic reactor of the second reaction stage with the same nickel-containing catalyst as packaged in Experiment 1, fed at an inlet temperature of ⁰ C, the outlet temperature rose to 625 ° C.

The weight ratio of butane to naphtha in the present case was 1: 3.43.

Test 5

Experiment 4 was repeated, but the butane to naphtha weight ratio was kept at 1.0: 15.7. This sank the outlet temperature of the adiabatic reactor of the second reaction stage to 537 ° C.

The results obtained in experiments 1 to 5 are in compiled in the following table:

-11-

209883/1030

Attempt no. 1 / / 2 1 / / 2 3 / 1 / / H 2 1 / f 5 2 Number of stages 1 500 544: 3.43 1 495 / 4oo / 3.43; / / 15.7 Weight ratio
of the to be treated until until \ / until until / / Hydrocarbons 53o 5oo 435 ' 53o 800 / 435 4oo 435 Temperature (° C) 26.1 .11.6 until 28.7 2, o * until until until 9.9 • 8.7 53o 9.9 33.8 625 800 ■ 537 - o, 5- o, i; 37.2 o, 5 4.8 29.4 2, o 29.8 Together- CH ^. 1o, 8 5.3 9 * ο 11.0 7.6 17.7 33,, 8 1o, 2 setting of the "
gaseous 2 52.7 74.3! o, 8 49.9 51.9 2.6 4.8 o, 7 Product CO 1oo, o Ιοο, ο j 13, o Ιοο, ο 1oo, o 12.3 7.6 11.7 (VoI *) - ^ ₂ 4o, o / 38.0 51.8 47.6 H ₂ O o, 72 ο, 24; 100, 0 ο, 86 1oo, o 1oo, o 1oo, o total / Amount of at 0.48 o, 92 o, 48 Ending everyone the Um- stage settlement o, 91 ' ο, 86 5oo hours after Attempt 3 * 72 start
required in ^the S ^e - Catalyst ^samX>

+ To compensate for the amount of hydrocarbons used, 1.9 of the catalyst required to treat the butane was added (the molar ratio of steam per 1 carbon atom of the butane being 1.5 .)

-12-

2O98R3 / 1030

Since the experiments 4 and 5 were carried out using a high-temperature steam reforming apparatus that requires relatively expensive equipment in the first reaction stage, the results of the measurements can be based on the amount of completion of the reaction 500 hours after start of the test ⁺ not compare directly; however, the methane concentration in the gaseous product is obviously far lower in experiments 4 and 5 than in experiment 2 carried out according to the invention.

These experimental results also show that in the experiment obtained gaseous product has a high methane concentration and is therefore ideally suited as a fuel gas.

Since when carrying out Experiment 4 with a weight ratio of butane to naphtha of 1: 3.45 in the reaction system When a large amount of hydrogen was present, a hydrogenating reaction occurred at the same time as the steam reforming reaction Decomposition and a rise in the catalyst temperature. These phenomena make it difficult to maintain the kata-Iytic Activity quite considerably.

Served to maintain catalytic activity one has hitherto been looking at an increase in the molar ratio of steam to fed-in hydrocarbons. The previous test results prove, however, that with the same amount of to end the reaction 500 hours after the start of the experiment required catalyst, the molar ratio of steam to injected hydrocarbons can be kept very small, if the method according to the invention described in Experiment 2 is used.

Example 2

By having a light hydrocarbon fraction with a A.P.I. gravity of 78.85 ° and a boiling point in the range

borrowed catalyst

209883/1030

of 57 ° to 119 ⁰ C "in mixture with steam in a ratio of 4 moles of steam per 1 carbon atom (the hydrocarbon fraction) by a nickel-containing catalyst having a Kieseiguhrträger at an inlet temperature of 517 ⁰ C (in

"kg ρ of the first reaction stage) and a pressure of ^ / cm Q with a feed rate of 0.1580 1 / h, a steam reforming reaction was carried out. The outlet temperature of the first reaction stage was 500 ° C; the composition of that exiting from the first reaction stage Gas was as follows:

CH _if '14 .25% (VoI)

H ₂ - 8.49

CO 0.16

CO ₂ 6.55

H ₂ O 70.57

A second steam reforming reaction was then carried out using a heavy. Hydrocarbon fraction with an API gravity of 47.60 and a boiling point in the range of 143 ° to 238 ⁰ C with both obtained in the first steam reforming reaction product gaseous as well as with unreacted steam in a ratio of 2 moles of total vapor (from the first reaction stage derived unreacted steam and freshly fed steam) per 1 carbon atom in the heavy hydrocarbon fraction and the mixture obtained is mixed through a non-carbonaceous catalyst with a Kieseiguhr as a carrier at an inlet temperature of 469 ° C (second reaction stage) and a pressure of ~ 5'j kg / cm ^ G was passed at a feed rate of 0.60 1 / hr. The outlet temperature of the second reaction stage rose to 54O ° C; the composition of the gas leaving the second Roaktion stage was as follows:

(209BR ₃ ZiO ₃ O

28.68 % (VoI) H ₂ 10.15

co 0.73

CO ₂ . . 12.68.

H ₂ O 47.76

As a result of measuring the temperature distribution in the catalyst bed it was found that the required to end the reaction 50 hrs, 100 hrs and 150 hrs after the start of the experiment Ordered amount of catalyst 0.530 kg, 0.588 kg büv /. ö, 600 kg fraud.

Comparative example

If the same batch is mixed with hydrocarbons with an API oath of 47.60 and a boiling point in the range from 143 ° to 238 ⁰ C (see Example 2) and steam in the ratio of 2 moles per 1 carbon atom in the hydrocarbon batch and the mixture obtained is mixed with a catalyst with kieselguhr as carrier in the first reaction stage at an inlet temperature of 484 ⁰ C and a pressure of 33 kg / cm ² G at a feed rate of 0.6 l '/ hr was passed through, the gas obtained had the following composition:

CH ₄ .. 25.41 % (VoI) H ₂ 10.35

CO 0.66

CO ₂ 12.10

H ₂ O 51.48

Since the catalyst is considerably impaired 10 hours after the start of the reaction and the pressure gradient in the reaction column has increased the attempt was not continued. Upon completion of the experiment, the catalyst was removed from the reaction zone carried out and examined. Here it turned out that that there is a carbonaceous material on the catalyst

2 0 9 8 8 3/1030

2230915

had deposited.

Example 3 .

First of hydrocarbon feedstocks were distilled with an IBP of 45 ⁰ C and a PBP of 243 ° C to obtain a light fraction having an IBP of 37 ° C and a FBP of 152 ^o C and a heavy fraction having an IBP of 144 ⁰ C and a FBP of'24.9 ° G to win.

The light Kohlenwasserstofffraktiori thus obtained was mixed with steam in a ratio of 4 moles of steam per 1 carbon atom in the hydrocarbon fraction, and the resulting mixture charged to a 0.6 kg of a nickel-containing catalyst with kieselguhr as carrier, adiabatically operating reactor at an inlet temperature of 515 ⁰ C and an internal pressure of 35 kg / cm G was fed. During the reaction, the hydrocarbon fraction was ■ fed in at a rate of 0.155 l / h. The outlet temperature was 500 ⁰ C.

The gaseous product obtained was then mixed with a heavy hydrocarbon fraction and steam in the ratio of 2 moles of steam (including unreacted steam from the first reactor and additional steam) to one carbon atom in the hydrocarbon fraction, whereupon the mixture obtained was poured into a second, 0, 8 kg of a nickel-containing catalyst with a kieselguhr support charged reactor at an inlet temperature of 465 ° C and a pressure of 33 kg / cm G with a feed rate (the heavy hydrocarbon fraction) of 0.61 l / h. The outlet temperature of the second reactor was 5 ^J 10 ° C; the gas obtained had the following composition:

₄ 28.78 VoI %

H ₂ 10.12 "

CO 0.71 "

CO ₂ "12.65"

H ₂ O 47.74 "

std after the onset of the reaction could be observed become that unreacted hydrocarbons have been blown out.

Comparative example

The hydrocarbon charges used in example j5 with an IBP of 45 ° C. and an FBP of 2Vj ⁰ C were brought into contact with a nickel-containing catalyst bed together with steam in a ratio of 2 moles H _{2 O to one carbon atom of the hydrocarbon charge without fractional distillation.} The nickel-containing catalyst corresponded to the nickel-containing catalyst used in Example 3.

In the present case the inlet temperature of the reactor was 487 ° C .; the internal pressure in the reactor was 15.5 kg / cm G. 15 hours after the start of the reaction, the reaction was stopped because there was a gradual increase in the pressure drop in the catalyst bed was observed. Here was - as the graphic representation of the temperature distribution in the catalyst bed shows severe impairment of the catalytic activity of the catalyst is to be expected.

After the reaction had ended, the catalyst was removed from the reaction zone discharged and examined, it was found that carbon-like material was deposited on the catalyst .would have.

-17-209883 / 1030

223Ü916

Example 4

0.5 1 butane charge, which was mixed with 0.72 kg / h of steam in a ratio of 1 mole of butane to 2 moles of steam, Viurde into the first reactor charged with a nickel-containing catalyst supported by a Kieseiguhr at an inlet temperature of 487 ° C and a Internal pressure in the reactor of 25.9 kg / cm G initiated. The outlet temperature was 500 ⁰ C.

The light emerging from the first reaction stage as G-/ was mixed with a naphtha IBP of 40 ° C, a PBP of 175 ° C and a specific weight of 56 ⁰ C in an amount of 0.37 1 hr, after which the mixture obtained in an inlet temperature of 489 ° C. was fed into a second reactor charged with a nickel-containing catalyst corresponding to the nickel-containing catalyst of the first reactor. The pressure in this reactor was kept constant at 25.9 kg / cm G. The outlet temperature of this reactor rose to 53O ⁰ C. The gaseous end product obtained in this way had the following composition:

64.2 % (VoI)

H ₂ 12.1 %

CO 1.6 %

CO ₂ . 22.1 %

The first and second reactors were with 0.4 and 0.5 kg of catalyst, respectively loaded. Even after operating the two reactors for 600 hours, there was still no unreacted naphtha punched through.

Comparative example

A mixture of 0.5 l / h butane and 0.37 l / h naphtha was produced with 0.72 kg / h of steam in the ratio of 0.99 moles of steam per 1 carbon atom mixed in the mixture, whereupon

-18-20 9R83 / 103Q

Put the mixture obtained into one with a nickel-containing one Catalyst according to Example 4 fed into the reactor.

After the reaction had started, the attempt had to be made aborted because of a continuous increase in Pressure drop in the catalyst bed was observed. On that vmrde the catalyst discharged from the catalyst bed and examined. It was found that on the Catalyst had deposited carbonaceous material.

-U-

20988 3/1030

Claims (1)

Patent claims '. Process for reforming hydrocarbons having at least ^ two carbon atoms per molecule in at least two stages, characterized in that an adiabatic steam reforming is carried out in the reaction zone of a first reaction stage in the presence of a nickel-containing catalyst at a temperature of 550 ° to 550 ° C Hydrocarbon fraction with a relatively low average molecular weight undertakes, 1.0 to 5.0 mol (e) of steam being admixed to each carbon atom of this hydrocarbon fraction, and then in the reaction zone at least one further reaction stage in the presence of a nickel-containing catalyst at a temperature of 300 ° to 55O ° C an adiabatic steam reforming of a hydrocarbon mixture, consisting of the gaseous reaction product from the reaction zone of the first reaction stage and a hydrocarbon fraction with a relatively high average molecular weight, is carried out, the ratio of steam to Hydrocarbon fraction with a larger average molecular weight is selected to be smaller than the ratio of steam to hydrocarbon fraction (with a lower average molecular weight) maintained in the first reaction zone. 2. The method according to claim 1, characterized in that one of petroleum refinery gases, liquefied natural gas, light naphtha, Runs out of heavy naphtha and / or kerosene. 5. The method according to any one of claims 1 and 2, characterized in that that one reformed in two reaction stages. + average -20- 209383/1030 Process according to claim 1, characterized in that the hydrocarbon part is low, medium Molecular weight and the hydrocarbon content with large average molecular weight by fractionating those having at least two carbon atoms per molecule Hydrocarbons wins. Process according to Claim 1, characterized in that the gaseous reaction product from the first reaction stage treated in the second reaction stage after it has been treated with additional steam and the hydrocarbon ■ has mixed proportion with a larger average molecular weight. 209883/1030