DE2403701A1 - Regeneration of catalysts in methane prodn. - from hydrocarbons, by substitution of hydrocarbons by methanol during use - Google Patents

Abstract

Methane-contg. gases are produced from 2-30C hydrocarbons, using Ni on a carrier as catalyst, by passing steam at pressures >1 atmos. and pre-heating to >250 degrees C to produce a temp. of 300-600 degrees C in the catalyst bed, in which the catalyst is simultaneously regenerated by wholly or partly replacing the hydrocarbon feed with methanol. Used for the mfr. of rich gases e.g. for use as natural gas substitutes. De-activation of the catalyst by carbonaceous deposits, as shown by a steady migration of the temp. profile through the bed, is reversed. Subsequent de-activation is not significantly faster e.g. half the original activity, as measured in bed thickness, can be maintained. Production of gas is not interrupted or permanently reduced.

Description

Process for the production of methane-containing gases with simultaneous Regeneration of the catalyst The present invention relates to a method for Generation of methane-containing gases with simultaneous regeneration of the catalyst, that for the low-temperature vapor splitting of hydrocarbons into so-called rich gases, or gas that can be exchanged for natural gas (SOG) is used.

In practically all catalytic reactions in which the chemical Equilibrium should be set and in which there is a catalyst bed Temperature profile, one observes a slow deactivation of the catalyst, recognizable by a constant migration of the temperature profile through the catalyst bed0 This behavior can be interpreted as follows: As a result of recrystallization under Reaction conditions, the active surface area of the catalyst decreases; this inactivation is usually still a chemical inactivation of the catalyst superimposed The chemical Inactivation of the catalyst can have various causes. So, for example catalyst poisons such as chlorine, sulfur, lead, and antimony that have been introduced into the reactants etc. cause inactivation. In the case of low-temperature naphtha cleavage with steam however, the kinetics of the reaction taking place is the main cause of the Consider loss of catalyst activity. The vapor splitting of higher hydrocarbons is namely a reaction that proceeds in partial steps, which takes place over more or less reactive, relatively short-lived species (molecular ions or radicals). These intermediate products are generally further split into H2 and CO; but it can also be through recombination processes or through polymerization reactions stable C, H-containing end products result.

Used rich gas catalytic converters occasionally contain up to 15 Wt% carbon; however, analysis shows that this type of carbon is still another contains a certain amount of hydrogen and they are actually high polymer hydrocarbons with a low H: C ratio. Such products so far in their constitution are not examined in more detail, are predominantly called "gum" or as in the literature "Kinetic Soot". The deposition of such products on the catalyst prevents the reactants from accessing the active centers of the catalyst surface, by clogging the pores of the catalyst; for this reason they humiliate the activity of fission catalysts.

It is known that especially the higher boiling, especially aromatic and naphthenic hydrocarbons in the low temperature naphtha cleavage contribute to increased deposition of kinetic soot and thus to deactivation lead of the catalyst used in this reaction.

In contrast to the chemical inactivation of the catalyst by Aging or catalyst poisons can block the active surface of the catalyst by gasifying the "gum" or "kinetic soot" formed be reversed.

For the regeneration of catalysts deactivated by kinetic soot a number of suggestions have already been made, e.g. regeneration with Rich gas or with hydrogen.

For example, it is known from the German Auslegeschrift 1 233 090, the formation of "so-called polymers" by recycling part of the Methane-rich fission products obtained from hydrocarbons in water vapor splitting (Reichgas) to delay. By recirculating the fission products, according to the information in this publication the service life of the catalyst increased (Equivalent to this, the exemplary embodiments 1 and 2).

In DAS 1 255 847, which comes from the same applicant, becomes Suggested increase in the life of the catalyst, the raw materials to be cleaved to pass into two or more successive sections of the catalyst bed and all of the necessary for the cleavage of the raw material (hydrocarbon) To supply water vapor in the first section With the previously proposed methods the regeneration of the catalyst is carried out while the system is in operation, however, in the former case, a lower one becomes because of the recycling of reaction product Throughput achieved than without recirculation. In the second case, only a part becomes of the catalytic converter protected from aging.

It has also already been proposed, the rich gas catalyst to regenerate with hydrogen (see Petroleum and Petrochemical International, February issue 1973, pages 50 ff, especially page 57).

When regenerating the rich gas catalytic converter with hydrogen, however, gas generation can be interrupted. Large gas generation plants come to a standstill as a result of the regeneration of the fission catalyst, however, it is out of the question in most cases, since the losses caused by the loss of production are often greater than the cost of installing a new batch of catalyst.

It has now been found that deactivated rich gas catalysts without the disadvantages outlined above can be regenerated if the for Splitting used raw materials (hydrocarbons or naphtha) in whole or in part replaced by methanol, namely until the temperature profile in the catalyst bed migrated back and came to a standstill0 In this way it is possible, for example, half of the original Activity reserve, measured in cm the catalyst bed length. The migration of the temperature profile only runs through the regenerated catalyst zone after the first regeneration marginally faster than with a freshly used catalyst.

The invention therefore relates to a method for producing methane-containing Gases from hydrocarbons with a C number from C2 to C30 on nickel catalysts on supports with simultaneous regeneration of the catalyst, the hydrocarbons together with water vapor at pressures of over 1 ata and preheating temperatures of above 2500C are passed through the bed of a nickel catalyst, its temperature by keeping the occurring reaction between 300 and 600 ° C. The procedure is characterized in that for the regeneration of the catalyst for the reaction zone the supply of hydrocarbons / is interrupted and methanol together with water vapor is passed through the catalyst bed and after regeneration of the catalyst the methanol supply is interrupted and again Eohydrocarbons together with Steam can be passed through the catalyst bed0 Another embodiment the invention relates to the fact that for the regeneration of the catalyst, the hydrocarbon feed is only throttled and one corresponding to the reduction in the amount of hydrocarbons Amount of methanol is added0 The basic process for the preparation of methane-rich gases through low-temperature splitting of hydrocarbons (naphtha) on nickel catalysts with steam has been around since the late fifties known (see DAS 1 180 481).

The further elaboration of this procedure is in the German interpretative document 1 233 090 (recycle of the cracked gas) as well as in the interpretative documents 1 240 618 (higher Preheating temperatures) and 1 255 847 (hydrocarbon split; hydrogasification) and in the laid-open German application 1 922 182 (cooling with reactants) described.

Regarding the development of the low-temperature cracking catalysts on the British patent specification 820 257, the German Auslegeschrift 1 227 603 (alkalization) as well as the published applications 1 470 700 and 1 545 442 (addition of alkaline earth metals, especially barium) as well as the published German application 1 545 428 (magnesium silicate referred to as carrier), for the process according to the invention come very generally the catalysts used for the low-temperature cracking of hydrocarbons into consideration. In particular, the German application disclosed 1 545 428 described alkali-free nickel catalyst, which after reduction nickel on amorphous magnesium silicate and by adding a water glass solution a solution of magnesium salts and precipitates of nickel is obtained, as well as the in the German patent application P 23 11 756o8 (O, Z, 29 248) described alkali-free Low-temperature cracking catalyst containing nickel, magnesium and aluminum has been tried and tested0 A magnesium-free catalyst is also preferably used for its preparation in the German patent application (see P 22 55 909o7 - OoZo 29 520) is described.

The method according to the invention can be carried out both in one and in several Reaction zones are carried out. In a particular embodiment of the method becomes both the flow direction of the water vapor and that of the regeneration Regenerating agent used, e.g. the methanol or the hydrocarbon-methanol mixture compared to that used for carrying out the splitting of hydrocarbons Direction of flow reversed This is when a reaction zone is used through installation corresponding valves in the supply lines to the inlet and outlet of the reaction zone or the reactor is possible. When carrying out the method according to the invention in two reaction zones or two reactors are corresponding supply and bypass lines to the Inputs and outputs of the two reactors with a corresponding Provide regular facial expressions. You can then alternate the cleavage in one reaction zone carry out of hydrocarbons while regenerating in the other zone or remove the no longer regenerable catalyst.

Even when carrying out the method according to the invention in two The flow directions for regeneration are the reaction zones or two reactors of water vapor and regenerant compared to that observed during the cleavage The direction of flow (in which the profile migration takes place) is preferably reversed.

The hydrocarbon feed is used to regenerate the catalyst interrupted to the reaction zone. The addition of steam to the reaction zone must, however must be guaranteed, otherwise when changing over to the one required for regeneration Raw material (methanol) could damage the catalyst. Preferred the amount of water used in the splitting of the hydrocarbon during the regeneration continues to be passed over the catalyst. (The preheater is on anyway designed for a specific performance; without special arrangements for regulation to meet, therefore the actual splitting of the raw material (naphtha) amount of water vapor used cannot be increased or decreased significantly, though this would be technically feasible.) In a special embodiment of the process according to the invention, however, only 50% of the hydrocarbons are through Replaced methanol. In the case of the last-mentioned embodiment, this naturally results slightly longer regeneration times.

The regeneration of the rich gas catalytic converter can be repeated several times will. However, the reactivation effect achieved in each case is getting smaller and smaller. It is possible to regenerate the rich gas catalyst preferably used 2 to 3 times to extend its service life e.g. by twice. One goal of the invention Procedure is when regeneration of the catalyst the same To achieve gas yield, as in the actual splitting of the hydrocarbons is achieved. This can be achieved by reducing the load on the catalyst is increased accordingly during the regeneration with methanol. There can be loads from 0.5 to 5 kg of methanol / l of catalyst / h can be granted. Usually there are loads used in the range between 1 and 3 kg of methanol catalyst / h. Will be used during the Regeneration only replaces part of the hydrocarbon with methanol, so, based on the proportion of methanol in the total amount to be converted Raw material, selected lower loads in accordance with the aforementioned areas.

The maximum reaction temperature in the contact bed is of the Depending on the type of raw material used. Must be used for regeneration with methanol a higher temperature rise can be expected. It is therefore the ratio of water vapor : To choose methanol so that the temperatures are high enough to avoid the "kinetic Soot "to gasify, on the other hand, however, the upper temperature limit, up to that of the Catalyst is thermally stable, is not exceeded. This upper limit is likely between 530 and 6000C for the various catalysts.

In general, water vapor: methanol ratios are therefore chosen from 1.5 to 4 kg of water vapor per kg of methanol; in particular, ratios of 1.5 to 3.0 kg of water vapor per kg of methanol applied. For the preheating temperatures the water vapor: methanol mixtures also apply limiting limits as for the load. In general, when using pure methanol, one chooses as the regeneration agent Preheating temperatures of 200 to 400 ° C, in particular those in the range between 300 and 380 ° C used. These preheating temperatures are generally somewhat lower than those for the cracking of hydrocarbon mixtures. For small circumstances of steam: In the above-mentioned areas, methanol is the lower preheating temperatures, for large ratios of water vapor : Methanol on the other hand the in higher preheating temperatures are applied in this area.

The time required for regeneration is essentially dependent on the state of the deactivated catalyst.

It can be a few hours to several days. Usually 3 to 40 hours are required for a single regeneration.

The methane-rich produced during the regeneration of the catalyst Gases can be released in the usual way, e.g. through post-methanation, C02 scrubbing, etc. processed into gases with a high calorific value (natural gas, SNG).

The process of the invention is shown in the examples below explained in more detail.

In Example 1 are catalysts that are based on the teachings of the German Auslegeschrift 1,227,603 under laid-open German application 1,545,428 have been described. It is also an example of the manufacture of a catalyst contain, which is particularly preferred according to the invention. It is the one from the catalyst runner Ni5 Mg A12 (OH) 16 CO3 4 rC H20 through calcination and reduction available particularly active low-temperature cracking catalyst. In example 2 are Comparative tests included. In this example the regeneration with steam, methane-rich gas (rich gas) and hydrogen of the regeneration according to the invention contrasted with methanol. From these experiments it is evident that the inventive Process for the regeneration of low-temperature cracking catalysts the known Procedure is superior.

In Examples 3 and 4, the regeneration of catalysts A and B described; Example 5 shows the multiple regeneration.

Example 1 The following is the preparation of the catalysts A, B and C.

A) Approx. 7.5 l of fully demineralized water are placed in a vessel, to this one leaves with stirring at 20 to 40OC within about 1 hour and at one The following solutions flow in with a pH value of 7 to 7.5: 1. 0.218 kg SiO2 in approx. 1.45 1 dilute water glass solution with an SiO2 content of 15 percent by weight; 2. 0.146 kg MgO in approx. 2.5 1 dilute magnesium nitrate solution with a Mg (N03) 2 content of about 20 percent by weight; 30 0.718 kg NaOH as 25 percent strength by weight sodium hydroxide solution.

The further solutions given below are added with stirring added to the precipitated, suspended, amorphous magnesium silicate (carrier): a) 0.637 kg NiO in approx. 4.0 1 approx. 15 weight percent nickel nitrate solution; b) 1.25 kg Na2CO3 dissolved in approx. 1.250 1 H20.

The deposited precipitate is carefully on the filter press Washed alkali-free. The filter cake is dried, ground, with 2 graphite blended and compressed to 5 x 5 mm tablets.

The tableted catalyst was calcined at 45,000 and exhibited a nickel content of 40 percent by weight, based on the oxidic contact. The rest is amorphous Mg-silicate. The bulk density was 0.92 g per cm3.

B) The catalyst B was according to the information in the German patent application P 23 11 756.8 - O.Z. 29 248 manufactured.

For the production of the catalyst precursor Ni5MgAl2 (OH) 16 003.4 H20 the following 2 molar solutions were prepared: lo 0.463 kg MgNO3 (20) Q6 H20 were dissolved in such an amount of H 2 O that a total solution of 0.9 1 resulted.

2. 2.845 kg Nun03 (2nd). 6 H20 and 1.45 kg Al (N03) 3.9 H20 were in H20 dissolved, so that a solution of 7.0 1 was formed.

3. 1.85 kg of Na2CO3 were dissolved in 9 l of H2O.

In a stirred tank with a glass electrode for continuous pH measurement was provided, 2.5 l of H2O were submitted, heated to 500G and with solution 3 adjusted to pH 10.

At constant pH and constant temperature, magnesium became as a hydroxide or as a basic carbonate by continuously combining solutions 1 and 3 failed.

After solution 1 had run in completely, the further addition was made set by solution 30 With a small amount of solution 2, the pH was now set in the template to 8 and at this pH and a temperature of 50 0C solution 2 and 3 continuously combined within 40 minutes. The fancy, partially crystalline precipitate was filtered off, the filter cake in 12 l of water suspended at 500C and stirred for a longer period of time. After about 4 to 5 The precipitate was filtered off with suction for hours, 5 hours at 95 ° C., 5 hours at around 11000 dried and then calcined for 4 hours at 5000C, with the drying temperature was heated up to the calcination temperature within 2 hours.

The analysis showed 50.3 percent by weight Ni, calculated as metal and based on the oxidic contact. The bulk density of the oxide catalyst was 0.96 g per cm3.

C) It was a catalyst according to the teaching of Example 1 of the German Auslegeschrift 1 227 603 produced, which calculated 1.65 percent by weight potassium as metal and based on the combined weight of metallic nickel and aluminum oxide, contained. (Compare catalyst E of the example of the cited patent application.) This catalyst (oxidic) had a bulk density of 1.05 g per cm3.

Example 2 Approx. 200 ml of each of the catalysts A, B and 3 into a vertically arranged reaction tube with a clear width of 2-4 mm filled in so that a contact bed height of approx.

50 cm. The reaction tube was made of a heatable aluminum block enclosed so that adiabatic reaction conditions could be simulated.

All catalysts were in the reaction tube at a temperature of 4500C and at a pressure of 30 ata for 12 hours with 600 liters of hydrogen per liter Catalyst and hour reduced.

A steam / naphtha mixture was poured over the catalysts reduced in this way (Boiling range naphtha 80 to 155OC, density 0.727 kg / l) with a load of 5 kg naphtha per liter of catalyst and hour at a preheating temperature of 3800C, a temperature of the aluminum block of 4500C, a pressure of 30 ata and with a weight ratio of water vapor to naphtha of 1.6 kg / kg. Included moves the maximum of the temperature in the reaction tube, which was originally at 32 cm Catalyst height is 48 cm in the course of 210 hours and it does not occur converted hydrocarbons in the cracked gas.

a) Regeneration of the catalyst B with steam via the, as above described, deactivated catalyst was steam with a for 5 hours Preheating temperature of 4500C and a total load of 10 kg steam per liter Catalyst and hour passed. The temperature profile maximum moves through this treatment from 48 to 46 cm and comes under the above when the gasoline is split again again to the 48 cm mark within 10 hours.

b) Regeneration with cracked gas (rich gas) To determine the effect of rich gas during regeneration became about 8000 for 5 hours 1 rich gas of the following composition (all data in percent by volume): methane 65; CO2 23; H2 11.2; CO 0.8 together with 10 kg of water vapor per liter of catalyst and Passed hour with a preheating temperature of 460 ° C through the reactor. Here the temperature profile maximum had migrated back from the original 48 to 45 cm and was again at the 48 cm mark within 22 hours after the gasoline was split again arrived.

c) with hydrogen There were 300 liters of hydrogen per for 5 hours Liters of catalyst and hour passed through the contact bed at a pressure of 30 ata. The temperature maximum moved back 6 cm to the 42 cm mark and was returned to the old 48 cm mark within 56 hours.

d) with methanol-hydrocarbon mixtures it was for 5 hours with a mixture of 2 kg of naphtha, 2 kg of water and 4 kg of methanol per liter of catalyst and hour (preheating temperature of the mixture 2500C) regenerated. The one in the catalyst layer the maximum temperature occurring was 509 ° C. The maximum temperature moved from 48 to 44 cm and was within 28 hours when the gasoline was split again back to the old mark. In this and the following experiment the direction of flow during regeneration compared to that during deactivation used direction reversed.

e) with methanol-water mixtures. The regeneration was carried out with 3 kg Methanol and 9 l of water per liter of catalyst per hour. This mixture was with a preheating temperature of 380 0C passed through the contact bed for five hours. The temperature profile maximum moved back from 48 to 42 cm and was again Gasoline splitting back to the old mark after 68 hours.

Example 3 Catalyst C is, as described in Example 2 above, deactivated. The same amount of water vapor and 3 kg of methanol are used for regeneration per liter of catalyst and hour with a preheating temperature of 350 ° C for five hours passed through the catalyst bed for a long time (arrangement as in Example 2 d). The temperature maximum moves to the mark of 42 cm and was among the above when the gasoline was split again the above-mentioned conditions return to the original mark (48 cm) after 44 hours arrived.

Example 4 The catalyst A was, as described in Example 2, deactivated. While maintaining the amount of water vapor, instead of naphtha 3 kg of methanol per liter of catalyst per hour at a preheating temperature of 350 0C passed through the catalyst bed for five hours (reversal of the direction of flow). The temperature profile maximum moved up from the original 48 cm mark the 44 cm mark and was again with renewed naphtha cleavage after 42 hours reached the 48 cm mark.

Example 5 Multiple regeneration with methanol.

The catalyst B was prepared as indicated above by cleavage of Deactivated naphtha. Instead of naphtha, 3 kg of methanol per liter of catalyst were then used and hour with a preheating temperature lowered to 3500C through the contact bed directed.

The originally selected proportion of water vapor was retained.

The temperature maximum (which in this case was 51,100) moved within from 6 hours back to 32 cm. The naphtha cleavage was then resumed. After the first hour, the maximum temperature was 40 cm. Within 86 hours it had moved forward again to 48 cm. The second regeneration with Methanol under the above-mentioned conditions there is a back migration of the temperature profile maximum to the 42 cm mark.

The renewed splitting of naphtha gave a breakthrough after 62 hours of unreacted hydrocarbons. The third regeneration with methanol under The aforementioned conditions resulted in a forward shift in the temperature profile maximum to the 45 cm mark. With the subsequent resumption of the naphtha fission could the running time has not yet been extended by 44 hours (regeneration with reversal of the direction of flow).

The 3-time regeneration thus reduced the operating time of the catalytic converter extended by 172 hours from the original 210 hours to a total of 382 hours will.

Claims (4)

Claims 1. Process for generating methane-containing gases from hydrocarbons with a carbon number of C2 to C30 on nickel catalysts on supports with simultaneous Regeneration of the catalyst, where the hydrocarbons were together with Vor Water vapor at pressures above 1 ata and temperatures above 250 0C through the Bed of a nickel catalyst are passed, the temperature of which by the entering Reaction is kept between 300 and 6000C, characterized in that for regeneration of the catalyst, the supply of hydrocarbons to the reaction zone is interrupted and methanol is passed through the catalyst bed together with steam Once the catalyst has been regenerated, the supply of methanol is stopped and again passed hydrocarbons together with steam through the catalyst bed will. 2. The method according to claim 1, characterized in that the hydrocarbon feed is interrupted without the steam supply to the reaction zone is throttled. 3. Process for generating methane-containing gases from hydrocarbons with a C number of 02 to C30 on nickel catalysts on supports with simultaneous Regeneration of the catalyst, the hydrocarbons together with water vapor at pressures above 1 ata and temperatures above 250 ° C through the bed a nickel catalyst are passed, the temperature of which by the entering Reaction is kept between 300 and 6000C, characterized in that for regeneration of the catalyst, the hydrocarbon feed is reduced and that of the reduction corresponding proportion of the hydrocarbon is replaced by methanol. 4. The method according to claim 3, characterized in that during the regeneration of the catalyst, the steam supply is not throttled.