DE1255847C2 - PROCESS FOR THE PRODUCTION OF METHANE CONTAINING GASES FROM HYDROCARBONS - Google Patents

Description

Water vapor over a nickel catalyst bed, in which all of the water vapor is with part of the total to be converted hydrocarbon vapors in a first stage and then the mixture after the remaining amount of hydrocarbon vapors has been added, the reaction is continued, is characterized in that one works in at least two stages, one being in the first stage a mixture of steam and some of the evaporated hydrocarbons preheated to at least 350 ° C passes through a nickel catalyst bed, the temperature of which is determined by the reaction taking place therein is kept at 400 to 550 ° C, and in at least one further stage a further part of the evaporated hydrocarbons with the gases of the first stage are mixed and the mixture thus formed is passed through a further nickel catalyst bed, the temperature of which is kept at 400 to 600 ° C by the reaction taking place in it, and that the weight ratio between the total water bed fed to each catalyst bed and selects the total distillate vapor higher than 1.6.

If all of the steam, but only part of the initial distillate, is fed to the first stage, then is the ratio between water vapor and hydrocarbon is high, which at this stage makes the Life of the catalyst is increased. The remaining Hydrocarbons with the gas produced and the non-split water vapor from the first stage mixed, and this measure makes it possible to reduce the proportion of water vapor in contact with the catalyst without increasing the total amount of water vapor based on the starting material. The life of the catalyst on the second stage is thereby compared to a One-step procedure, extended in a similar manner.

Preferably two stages are used and regardless of this, the precedes each stage admixed proportion of evaporated hydrocarbons preferably in the inverse proportion to the number of levels applied.

The sections can be arranged in a single vessel or in separate vessels, provided that there is always a thorough mixing of the vaporized hydrocarbon with the gases from the previous section is guaranteed.

To avoid carbon deposits on the catalyst, it may be necessary not to let the catalyst temperature rise above 575 ⁰ C in some cases.

The weight ratio between water vapor and evaporated hydrocarbons in the over The gases passed through the catalyst must not be less than 1.6, preferably not less than 2.0. This ratio increases as soon as the evaporated hydrocarbons are split and becomes infinite, when the implementation is complete.

The gases entering the catalyst bed must be at a temperature of at least 350 ° C be preheated to ensure sufficient catalyst activity. The preheating temperature is up through the risk of thermal decomposition of the evaporated hydrocarbons and by the condition that the catalyst by the heat of reaction within a certain temperature range should be kept limited and depends on the proportion of existing vaporized Hydrocarbons.

According to the invention, the calorific value of a by the gasification of the distillate with steam Increase the gas obtained, since by adding distillate at each stage the methane content in the gaseous end product is continuously increased.

The effect of the gradual addition of the Destil-LO lats to the catalyst based on the amount of steam in contact with the catalyst is given in the following Table given.

Table I.

Reactant dimer
(Mole) \ One
step Two
first
step stages
second
step distillate 1.0
9.75
9.75 0.5
9.75
19.50 0.5
7.97
15.94 Steam
Ratio of water vapor to
distillate

The steam entering the second portion of Zweistüfenverfahrens, namely, 7.97 mol, represents the non-split portion of the current supplied to the first stage of water vapor. The values refer to an operating temperature of 500 ° C in one-step and to 460 ⁰ C and 500 ⁰ C on the first or second stage of the two-stage process. The weight ratio between steam and distillate is 2. The use of a larger number of stages makes it possible to bring higher amounts of steam into contact with the catalyst, which is particularly advantageous when high-boiling distillates are gasified with a very small amount of steam. The subject of patent 1,227,603 is improvements and modifications of the process described in British patent specification 820,257, which is aimed at extending the life of the catalytic converter. The process according to the invention can, if desired, also be carried out together with the process protected in this patent.

Two methods according to the invention are described below as examples.

example 1

A petroleum distillate with an average of 6.1 carbon atoms per molecule, a boiling range from 26 to 140 ° C and a specific gravity of 0.68 at 20 ° C was used in both parts of the example. The petroleum distillate was freed from sulfur compounds to less than 0.00002% for comparison mixed with steam in amounts of 2 parts by weight per part by weight of distillate steam. The mixture was preheated to 450 ° C and downward under a pressure of about 24.5 atmospheres passed through a bed of nickel-alumina catalyst about 30 cm deep. The catalyst bed was kept at a temperature of 506 ° C. by the heat of reaction. The mixture was with a space velocity of 44,000 parts by volume of mixture per part by volume of catalyst per hour and passed at a linear speed of about 50 cm / sec until undecomposed distillate in the out for the first time gases escaping from the bed occurred, which

sign for the end of the experiment was counted. .

In a second experiment, the same distillate was mixed with 4 parts by weight of steam per part by weight of distillate vapor. The mixture was preheated to 450 ° C. and passed under a pressure of about 24.5 atmospheres downward through a bed about 15 cm deep of the same catalyst as in the first experiment. The gaseous product and undecomposed water vapor emerged from the bed at a temperature of 460 ° C and "were mixed with the same amount by weight of distillate vapor as in the first bed and passed through a second, approximately 15 cm deep, nickel-alumina- The temperature of the catalyst in the second tube was maintained by the reaction at 502 ° C. The mixtures were passed through each bed at a linear velocity of about 50 cm / sec and a combined space velocity of 44,000 parts by volume of mixture per part by volume of catalyst per hour , until undecomposed distillate appeared for the first time in the gases emerging from the lower tube, which was taken as an indication of the end of the experiment.The results of the two experiments are compared with one another in Table II below.

Table II

attempt

, Time until undecomposed distillate appears

260 hours
1520 hours

The composition of the gases obtained in the two experiments was as follows:

Table III

Attempt 1 Attempt 2 second first step 11.05 step 10.75 Volume percentage CO ₂ ...... 0.45 7.20 0.40 Volume percentage CO 8.50 0.15 8.25 Volume percent H ₂ 31.20 6.80 32.70 Volume percentage CH ₄ 48.80 18.65 47.90 Volume percent H ₂ O 67.20

Example 2

A petroleum distillate with an average of 10.0 carbon atoms per molecule, a boiling range from 112 to 245 ° C and a specific gravity of 0.79 at 20 ° C, which is down to less than 0.00002 ° / o of sulfur compounds was used in two comparative experiments. In the first experiment, the petroleum distillate was steamed with 2 parts by weight mixed per part by weight of distillate vapor. The mixture was under a pressure of about Preheated 24.5 atmospheres to 530 ° C and down through a 30 cm deep bed of nickel-alumina catalyst directed. The catalyst bed was kept at 535 ° C. by the reactions that occurred. The mixture became catalyst at a space velocity of 11,000 parts by volume per part by volume pnd hour and a linear velocity of about 13.5 cm / sec passed through the bed until the first time

ίο undecomposed distillate in the emerging from the bed Gassing occurred, which was taken as an indication of the termination of the experiment.

In the second experiment, the same distillate was treated with 4 parts by weight of water vapor per part by weight Distillate vapor mixed. The mixture was preheated to 530 ° C and under a pressure of about 24.5 atmospheres downward through an approximately 15 cm deep bed of the same catalyst as in the first experiment. The gaseous product and undecomposed water vapor emerged at a temperature of 500 ° C the bed and were with the same amount of weight of distillate vapor as before entering the first Tube into a second nickel-alumina catalyst located under the first bed, about 15 cm deep headed through the bed. The temperature of the second catalyst bed was determined by the subsequent reaction held at 535 ° C. The mixtures were at a combined space velocity of 11,000 parts by volume per part by volume of catalyst and hour and a linear speed of about 13.5 cm / sec passed through each bed until the first undecomposed distillate in the emerging from the lower bed Gassing occurred, which was taken as an indication of the termination of the experiment. The results of the both experiments are compared in the table below:

Table IV

Attempt Time until undecomposed distillate appears

152 hours
602 hours

The composition of the gases obtained in the two experiments was as follows:

Table V

Attempt 1 Attempt 2 second first step 12.3 step 12.15 Volume percent CO ₂ 0.65 8.35 0.65 Volume percentage CO 10.4 0.35 10.6 Volume percent H ₂ 30.9 12.0 31.1 Volume percentage CH ₄ 45.75 15.4 45.0 Volume percent H ₂ O 63.9

Claims (3)

1 . 2 ■ were chosen in order to avoid carbon deposits on ■ patent claims: the catalyst. The proportion of water vapor, based on the hydrocarbons, is 1. Process for the production of methane-containing larger than the gen gases split during the reaction from evaporated, predominantly paraffi- 5 and the required steam excess depends on the niche hydrocarbons with an average of 4 average molecular weights of the up to 15 carbon atoms per molecule used by excess hydrocarbons, and increases with increas passing a preheated to at least 35O ⁰ C mendem molecular weight. The excess of each mixture of evaporated hydrocarbons is not great, and you can use 1.6 parts by weight and water vapor over a nickel catalyst bed, io water vapor per part by weight of hydrocarbon in which all the water vapor is used with all the hydrocarbon mixtures that are part of the total hydrocarbons to be converted - Average of 4 to 10 carbon atoms per molecule. Since the water vapor is in excess, the mixture, after adding the remaining amount of the hydrocarbon vapors exiting the catalyst bed, always contains a certain proportion of water vapor, is brought further to the reaction, because the composition of the gases formed is characterized by, that one is determined in at least chemical equilibria, that works in two stages, with the water vapor present in the first product unchanged, stage a preheated to at least 350 ° C provided that the working temperature, the mixture of water vapor and a part the pressure and the ratio of the reactant-vaporized hydrocarbons due to a nickel mer also remain unchanged. 'Catalyst bed conducts, the temperature of which by The said patent also describes the the conversion taking place therein to 400 to post-treatment of the methane-containing products thus produced 550 ⁰ C is maintained, and where one in min gases, the methane concentration on the ge at least one further step to reduce a further part 25 of the desired value, of the evaporated hydrocarbons with the It has also been found that the well-known Gases of the first stage are mixed and this is done according to the invention with predominantly paraffin The mixture formed by a further nickel catalysis see hydrocarbons with an average of 4 to sator bed, the temperature of which is applied by the 15 carbon atoms per molecule in it following reaction kept at 400 to 600 ° C 30 den can. It was also found that the is, conducts, and that the weight ratio carrying out the reaction between the carbon between all of the hydrogen and the water vapor in each catalyst bed in the described supplied water vapor and the entire NEN way limited the life of the catalyst Selects distillate vapor higher than 1.6. ' is. Limiting the life of the catalyst 2. The method according to claim 1, characterized in that the higher the average, the stronger indicates that the proportion of the evaporated molecular weight of the hydrocarbons used, before each stage of mixed hydrocarbons and the lower the ratio between the selects substances so that it is in inverse proportion - water vapor and the hydrocarbon. Counter tennis corresponds to the number of levels used. status of the earlier patent 1 226 738 is a process 3. The method according to claim 1 and 2, characterized in 49 for the continuous catalytic cleavage of tables characterized in that the catalyst is in the two-volatile hydrocarbons or mixtures th or each subsequent stage through the associated therefrom for the purpose of heating gas generation, with a preceding one Implementation at a temperature of cleavage zone a mixture of water vapor and 50 to 400 to 575 ° C is maintained. 65% of the total hydrocarbons to be converted 45 substance vapors in a volume ratio of 3 to 7 to 1 is converted to water gas, which is essentially only carbon contains lenmonoxide and hydrogen, and in one Main cleavage zone, the water gas produced with the remaining amount of hydrocarbon vapors to a heating In British patent specification 820 257, a valuable gas is implemented. This creates a drive back mixtures for the production of methane-containing gases from polymer formation in the pre-cleavage zone with predominantly paraffinic charcoal. '. Hydrogen described, with the hydrocarbons, In contrast, the invention provides an improvement in vapors and water vapor in the atmosphere or a modification of that described in British patent pressure or above through a bed of nickel 55 font 820 257, already passed in the first catalyst and wherein the hydrocarbon stage leading to methane-rich gases process vapors and water vapor at a temperature of. It is based on the observation that the life of the catalyst is passed more than 350 ° C into the catalyst bed, so that the bed by the reaction of a can when the output held in two or distillate temperature in the range of 400 to 55O ⁰ C for 60 more consecutive sections of the Katalywird. . Satorbettes passes, with all the steam in the The pressure can be up to 50 atmospheres, the first section is initiated
but can also be higher if desired. The inventive method for production The most suitable pressures are in the range of 10 methane-containing gases from vaporized, over to 25 atmospheres. The lower temperature limit 65 predominantly paraffinic hydrocarbons with im 400 ° C was chosen because of an inclination means 4 to 15 carbon atoms in the molecule to reduce the activity loss of the catalyst to pass over a preheated to at least 350 ° C the, while 550 ° C as the upper temperature limit mixture of evaporated hydrocarbons and