DE1220836B - Process for the regeneration of catalysts - Google Patents

Description

Process for the regeneration of catalysts The invention relates to focus on the regeneration of deactivated catalysts necessary for the conversion of petroleum hydrocarbons at low temperature, especially for isomerization of C4 and higher paraffinic hydrocarbons boiling in the gasoline range (i.e. up to 2000 C) used at low temperature. Uriter "low temperature" is one Temperature below 204 "C to understand.

The conversion of petroleum hydrocarbons at low temperature, in particular the isomerization of C4 and higher paraffin hydrocarbons boiling in the gasoline range, can be carried out with catalysts that contain an inorganic oxide - preferably aluminum oxide, a metal of the platinum group and chlorine, the latter being Friedel-Crafts Metal chloride, for example aluminum chloride, or by reacting the aluminum oxide with a compound of the general formula in which X and Y can be identical or different and H, Cl, Br, F or SCl, or in which X and Y together can mean O or S, under non-reducing conditions and at a temperature such that the aluminum oxide takes up chlorine without that free aluminum chloride is formed was introduced into the catalyst.

The manufacture of the second type of catalyst is the subject of the German Patent 1,194,378, and its use for low temperature isomerization is the subject of German patent application B 63 918 IVb / 12 o. Both types of catalyst gradually lose their activity. Since they would represent expensive materials a significant reduction in the cost of the isomerization process is achieved if there is there would be a method for regenerating the catalysts.

It is obvious, however, that the manufacturing process of the two Catalyst types is very different. The active catalyst sites are in the first type by adding both aluminum and chlorine and in the second Type formed by the addition of chlorine alone. This increases the ability to regenerate affects the catalysts, and the regeneration of catalysts of the first Type causes considerable difficulties. However, it has been found that catalysts of the second type can be regenerated.

The invention relates to a process for the regeneration of deactivated catalysts which are suitable for carrying out reactions of the Friedel-Crafts type and which are originally produced by reacting activated aluminum oxide, which optionally contains a hydrogenation-active metal from Group VI a or VIII of the Periodic Table, with compounds of the general formula in which X and Y can be identical or different and are H, Cl, Br, F and / or SCl, or X and Y together are 0 or S, under non-reducing conditions at 149 to 593 "C in such a way that Chlorine is taken up by the oxide without the formation of free chloride, which is characterized in that the catalysts freed from reactants are treated with an oxygen-containing gas at 121 to 6500 C and then chlorinated again with the compounds of the general formula given above under the conditions mentioned above .

Platinum-alumina-halogen catalysts are known and will be used for reforming or isomerization processes at high temperature. It is also known that these catalysts can be regenerated, but both differentiate between the catalysts in question and the regeneration methods for the following reasons: 1. The usual catalysts for reforming high temperature are not active for isomerization at low temperature, because the activity at low temperature is the result of the special shape, in which the chlorine is present.

2. Both oxidation alone and re-halogenation alone normally have high temperature reforming catalysts result in a significant increase in the activity of the catalyst while detected was that with the catalysts used according to the invention the application only one of the two measures does not bring any advantage.

Any forms of aluminum oxide can be used in the catalysts will. However, one of the forms is preferred whose suitability as a carrier of catalysts, which are used for the catalytic reforming of petroleum hydrocarbons, is known. In these carriers the aluminum oxide is usually γ-aluminum oxide, Aluminum oxide or a mixture of these oxides with possibly some amorphous aluminum oxide. Particularly preferred is one derived from an alumina hydrate precursor Oxide form in which the trihydrate predominates.

Particularly suitable is an aluminum oxide form that has a larger one Contains proportion of ß-aluminum oxide trihydrate. The aluminum oxide can be used in the usual Way by hydrolysis of an aluminum alcoholate, e.g. B.

Aluminum isopropoxide, in an inert hydrocarbon solvent, z. B. Benzene, produce.

All other things being equal, the activity of the catalyst is the higher the greater the amount of chlorine absorbed by the aluminum oxide, and there the maximum amount of chlorine that can be attached to the size of the surface in Is related is a large surface area of alumina of, for example more than 250 mg, preferably more than 300 m2 / g, is desirable.

Preferably the alumina contains a small amount, for example less than 25 percent by weight, of a metal or a metal compound of the Groups VIa and VIII of the Periodic Table with hydrogenation activity. Is preferred a @ enn @@ Platinum group metal, which is present in an amount of 0.01 to 5 percent by weight, preferably from 0.1 to 2 percent by weight, may be present. Preferred as metals of the platinum group are platinum and palladium.

If the catalytic converter shows signs of deactivation and its- If regeneration is deemed necessary, the feed supply is interrupted and rinsing the catalyst bed to remove the reactants. The flush expediently takes place with an inert gas, for example nitrogen, exhaust gas from a Inert gas generator or hydrogen. Hydrogen is preferred, especially when it is normally passed through the reaction zone during processing. the In this case, rinsing takes place simply by interrupting the feed of the feedstock, while the hydrogen continues to pass through. The temperature during the Rinsing is conveniently the same as in processing; i.e., it can under 204 "C. The flow rate of the inert gas and that for a sufficient The length of time required for flushing can easily be determined, for example, by analysis determine the purging gas emerging from the reaction zone. For example, are suitable 100 to 1000 V gas / V catalyst / hour or even larger quantities and a rinsing duration from 10 minutes to 12 hours. The pressure applied is not critical. He can be the same as during processing. However, the subsequent treatment is carried out with an oxygen-containing gas normally at normal pressure, If the processing is carried out under the increased pressure, the pressure must be prevented. This pressure reduction is expediently carried out before or during the flushing.

The simultaneous presence of hydrogen and oxygen during regeneration would of course be undesirable. Therefore, when flushing with Hydrogen is carried out, this must be carried out before the introduction of the oxygen-containing Gas can be removed, for example, by displacement with an inert gas.

The treatment with the oxygen-containing gas (hereinafter for simplicity for the sake of calling it burning off ”) must of course be at such a temperature and be carried out under such conditions that damage to the catalyst is avoided.

(Such damage would be, for example, the conversion of the aluminum oxide of the catalyst in aluminum oxide or crystallization of the optionally present Metal of the platinum group.) Temperatures in the range from 121 to 650 "C are suitable.

A temperature range of 204 to 5380 C. is preferred. The duration Burning off can take 2 to 48 hours. If necessary, it can burn off gradually increasing the temperature within the range from 204 to 538 "C over a period of 5 to 20 hours.

Oxygen or air can be used as the oxygen-containing gas. However, since the oxygen content of the gas affects the rate and shape of the burn as well as the temperature reached plays a role, the oxygen or the air preferably with an inert gas, e.g. B. nitrogen, diluted.

A gas mixture containing 0.1 to 5 percent by volume of oxygen is suitable contains. The exact amount of oxygen and the amount used regulated so that temperatures in the above ranges are obtained.

The re-chlorination of the oxygen-treated catalyst can be done in the same way as the chlorination of the original catalyst. The details of this chlorination are given in German Patent 1,194,378 and are essentially described below: A special feature The chlorination is the use of the specific compounds of the above general formula. With these compounds there is a very specific form of chlorination obtained in the active catalysts for the conversion at low temperature are formed. The specific nature of the compounds used is determined by the The following examples of compounds illustrate the active and inactive catalysts, respectively result.

Compounds that make active catalysts: carbon tetrachloride (CCl4) chloroform (CHCl8) methylene chloride (cHacl2) dichlorodifluoromethane (CCl2F2) Trichlorobromomethane (CClaBr) thiocarbonyl tetrachloride (CCl3SCl) compounds that inactive catalysts result in: hydrogen chloride (HCI) chlorine (Cl2) methyl chloride (CH3Cl) acetyl chloride (CH3COCl) dichloroethane (CH1Cl - CH2Cl) tetrachloroethane (CHCl2 - CHCl2) Tetrachlorethylene (CCl2 = CCl) In the case of compounds that, in addition to chlorine, Carbon and hydrogen contain other elements, these can be removed by the Treatment can be introduced into the catalyst in addition to the chlorine. For example a treatment with dichlorodifluoromethane has the consequence that the catalyst both Absorbs both chlorine and fluorine. It was found that also produced in this way Catalysts for the conversion of hydrocarbons at low temperature are active and, in addition, other properties that result from the attachment of the other elements result, may have. Of the connections that are active Catalysts are carbon tetrachloride, chloroform and methylene chloride preferred.

The compounds falling under the general formula in which X and Y together are 0 or S are phosgene and thiophosgene.

The non-reducing conditions used for chlorination can be either inert or oxidizing conditions. To be favoured the latter because they result in catalysts that reduce their activity during isomerization lose more slowly at low temperature. A simple me- method of treatment The alumina consists of the chlorine compound as a gaseous stream either alone or preferably in a non-reducing carrier gas over the aluminum oxide to direct. Suitable carrier gases are, for example, nitrogen, air and oxygen.

Non-reducing conditions are essential as reducing conditions convert the chlorine compound into hydrogen chloride, which becomes an inactive catalyst leads. The chlorination temperature is between 149 and 5930 C. The tendency to The formation of free aluminum chloride increases with increasing temperature. Man must therefore be careful when at the higher temperatures in the specified range is being worked on. Because the temperatures used are usually above the volatilization temperature of aluminum chloride, the formation of free aluminum chloride can easily be discovered by its appearance in the gaseous reaction products. if a catalyst composed of the platinum group metal and alumina care must be taken to prevent the formation of volatile platinum complexes will. The tendency to form such complexes also increases with increasing temperature stronger. In the treatment of catalysts made from the platinum group metal and aluminum oxide, the temperature is preferably between 149 and 371 "C, with platinum on aluminum oxide for the treatment of combinations expediently Temperatures between 232 and 316 "C and for the treatment of the combination palladium temperatures between 260 and 3430 C can be applied to aluminum oxide.

The chlorination reaction is exothermic and at the temperatures indicated it concerns the initial temperatures used.

The rate of attachment of the chlorine compound is so slow as possible to ensure uniform chlorination and rapid temperature rise as a result of the exothermic reaction. The attachment rate is preferably not more than 1.3 percent by weight of chlorine compound per minute, based on the catalyst.

When a carrier gas is used, the flow rate is preferably at least 200 V / V / hour. A range from 200 to is suitable here 1000 V / V / h It is expedient to work at normal pressure.

The amount of chlorine absorbed by the catalyst depends on the same Factors that are decisive during catalyst manufacture. The amount of chlorine, which can be attached without the formation of free aluminum chloride stands on the surface of the catalyst and has a surface area of about 3.0 to 3.5 10-4 g / m2 of the original catalyst. Maximum chlorination of the catalyst is preferred, however, active catalysts are still obtained even with lower amounts of chlorine.

A range from 2.0 10-4 to 3.5 is suitable. 5-10-4g / m2.

It must be expected that the burning will cause a considerable Amount of original chlorine is removed. In practice, up to 50 percent by weight the compound used for the chlorination, based on the catalyst, while the chlorination are passed over the catalyst.

The various stages of the regeneration process as well as the preferred ones Conditions are listed in Table 1 below.

Table 1 More preferred Level Gas Temperature Remarks area ° C Flushing hydrogen 65 to 177 Flushing to remove the reaction Attendees. Reduced pressure up to Normal pressure Burning off inert gas with regulated acidic to 482 temperature control by the oxygen substance content content of the gas Chlorination of air and CCl4 232 to 316 chlorination temperature by blowing in kept below 343 ° C by CCl4. Overall including blown CCl4 up to 500 / o des Catalyst weight Example 1 I. Preparation of a fresh catalyst A 125 cm3 of a commercially available platinum-aluminum oxide catalyst, which consisted of 0.57 percent by weight of platinum and 0.81 percent by weight of chlorine on aluminum oxide, were placed in a glass reactor and treated as follows: a) The catalyst was dried in flowing nitrogen at 2600 C for 2 hours. During the entire duration of the treatment, the space velocity of the gas flowing downwards was 500 V / V / hour. b) The catalyst was treated with 24% carbon tetrachloride (based on the weight of the catalyst used) at 2600.degree. The carbon tetrachloride was added dropwise above the catalyst bed into the nitrogen stream used as carrier gas, by means of which the vaporized CCl4 was passed over the catalyst. The amount of CCl4 added exceeded 0.8 g / min. not. c) The treated catalyst was flushed for a further hour with nitrogen at 2600 ° C. and then transferred to a dry, airtight container. This catalyst was named "Catalyst A".

II. Use and Deactivation of Catalyst A Four 30cc samples of Catalyst A were tested for their activity at the low temperature Isomerization of hexane tested under the following conditions: Temperature ................... 132 ° C pressure ...... ...... 18.5 kg / cm2 molar ratio H2: hydrocarbon ................ 2.5: 1 space velocity of the liquid input ......... ................ 2.0 V / V / hour.

A dearomatized C6 cut from a refinery light gasoline served as an insert, which contained 0.1 percent by weight of CCl4 as an additive. The average Test duration was 50 hours, the initial conversion to 18% 2,2-dimethylbutane in the not stabilized liquid product in the 50th hour to an average of 12.5 percent by weight fell. The spent catalyst particles were hydrogenated at 132 "C for 1 hour purged and cooled to room temperature under nitrogen. You were in an ordinary, Transfer to dry, airtight containers and mix well to ensure uniformity.

This catalyst was named Catalyst B.

III. Treatment of the catalyst B 30 cm3 of the catalyst B were filled in a glass reactor and with 14 weight percent CCl4 (based on the catalyst) treated in the same way as Catalyst A. This catalyst was referred to as catalyst C.

IV.

30 cm3 of catalyst B were gradually increased to 499 ° C. in air heated. The temperature was brought to 260 ° C within 2 hours, Increased every hour by 55 ° C up to 499 ° C and held at this level for 2 hours.

V. (Catalyst D) 30 cm3 of the catalyst B were added in stages heated to 499 ° C in the same way as Catalyst D. The catalyst was then placed in a glass reactor and with 14 weight percent CCl4 in the same Way treated like catalyst A.

This catalyst was named Catalyst E.

VI. Activity tests Small parts of Catalysts B, C, D and E were analyzed for chlorine and carbon content.

The remaining parts were then checked for their activity in the case of low temperature carried out isomerization of hexane under the same conditions and using the same feedstock as described under II. The results of the activity tests are shown in Table 2 below. For comparison, the results obtained with the fresh catalyst A are shown.

Table 2 Activity test results increase sales Catalyst 2,2-dimethylbutane weight percent after a running time of Weight percent Weight percent 6 hours ß 21 hours 30 hours A 11.2 0.02 18 15.5 5 12.5 B 9.5 1.13 9 7 C 10.4 0.78 8 D 3.1 0.02 4 - - E 10.5 0.02 17 16 - The chlorine and carbon contents indicated that the deactivated catalyst B had a lower chlorine content and a significant carbon content compared to the fresh catalyst A. As a result of chlorination to form catalyst C, the chlorine content increased, while the carbon content decreased only to a limited extent. Heating in air to form Catalyst D removed the carbon but also removed the chlorine.

Only the catalyst E, which is used to remove the carbon on the Air heated and then chlorinated contained chlorine and carbon similar to those of the fresh catalyst A.

The activity test of the catalyst B showed that the deactivation was permanent and that with further use for the isomerization another Deactivation occurred. The experiments with catalyst C, which is re-chlorinated, but had not been heated in air, and with the catalyst D, which was on the Air heated but not chlorinated indicate that neither treatment had an appreciable influence on the activity of the catalyst. Were however the treatments combined as in the case of Catalyst E became the original Activity of the catalyst restored.

Example 2 I. Preparation of the catalyst F 65 g of a platinum-aluminum oxide-halogen catalyst, the 0.57 percent by weight of platinum and 0.81 percent by weight of chlorine on aluminum oxide were placed in an upright, tubular glass reactor, whereupon dry nitrogen in an amount of 48 l / h. from top to bottom over the catalytic converter was directed. The temperature of the catalyst was increased to 288 ° C and on this Height held.

After 2 hours there was carbon tetrachloride in the amount of 13 g / h blown into the nitrogen stream. After 2 hours, as 26.2 g carbon tetrachloride Had passed over the catalyst, the addition of the carbon tetrachloride canceled. After purging with nitrogen at 288 ° C for an additional hour the catalyst was cooled to room temperature - and quickly transferred to a dry, refilled airtight container. There was an increase in the weight of the catalyst 6.9% found. An analysis of the catalyst showed chlorine ................ 13.3 weight percent carbon ... 0.02 weight percent hydrogen. 0.05 percent by weight Surface .......... 327 m2 / g pore volume. 0.29 cm3 / g II. Use and regeneration of the catalyst F The catalyst F was charged in an amount of 25 g in a reactor filled and checked for its activity under the following conditions: temperature ................. 1320 C pressure ................ ...... 18.5 kg / cm2 molar ratio H2: hydrocarbon. . . . . 2.5: 1 space velocity of the liquid input .................... .. 1.0 V / V / hour

The input materials used and the results obtained are listed in Table 3. After a term of. 66 hours became the catalyst regenerated as follows: The reactor was flushed with hydrogen for one hour and the pressure is then reduced to normal pressure.

The system was purged with nitrogen, followed by air in an amount from 15 1 / h was passed through. The temperature was to avoid one too Sudden burning carefully increased as follows: a) 132 to 204 "C 33 / d .. hours b) 204 to 232 ° C. 1 hour c) 232 to 260 ° C ..... 1 hour d) 260 to 482 ° C ........... 4½ hours e) 482 ° C. 1 .......... hour Particular care was taken in the temperature range proceed from 204 to 260 ° C, since the perceptible »burn-off« started in this area. The catalyst was cooled to 288 ° C. while air was passed through and then within of one hour with 8.4 g of carbon tetrachloride (32.3 percent by weight of the catalyst) treated. Seven minutes after the start of treatment with carbon tetrachloride was made recorded a maximum catalyst temperature of 3020 C.

After the addition of the carbon tetrachloride, the catalyst temperature became to 482 ° C in the same way as under d) and e) while passing through 151 air increased per hour and then decreased to 132 "C. After purging with nitrogen, the conditions of the activity check set again.

The results in Table 3 show that initially, when benzene, C7 and higher hydrocarbons, and sulfur were low or absent from the feed, the catalyst worked well. After changing the use by including these components, the activity of the catalyst fell sharply. However, after regeneration of the catalyst and return to the original use, the activity of the catalyst was completely restored. Table 3 Bet Bet 1 run time Bet 2 run time ~ Bet 3 'run time Components +0.1 weight hours +0.1 weight hours +0.1 weight hours Weight percent percent CCl4 6 1 39 percent CCl4 49 to 66 ~ protent CCI4 72 1 108 Propane ............... lane lane - 1 lane - lane lane Isobutane. . . ...... - 0.5 0.5 - 2 0.5 - 0.5 0.5 n-butane .............. track track track - track track track track track Isopentane. . . . . . . . . . . . . Lane 2.5 2.5 Lane 1 Lane Lane 1 1 n-pentane. . . . . . . . . . . . . . 4.5 1.5 1.5 1.5 1 1 5d 1.5 0.5 0.5 2,2-dimethylbutane 3.5 3.5 24 23.5 0.5 10.5 1 2.5 2.5 28.5 29 2,3-dimethylbutane 335 45 4 39 40 39 2-methylpentane -. 5 40.5 0, to 40.5 36 25.5 36 30.5 3-methylpentane. . . . . . . . 23 15.5 16 16 15 12.5 5 22.5 15.5 15.5 n-hexane. . . . . . . . . . . . . . 30- 11 11 31 15 29 30 10 10.5 C, -naphthenes 5,5. . . . . . . 5.5 4.5 4.5 13.5 12.5 15 4.5 4 4 Benzene ............... 0 - - 0.5 trace 0.5 0 - - C7 etc. - - 11.5 6 10 - - - Sulfur, ppm 0.6 - - 250 - -. 0.7 250 - -

Claims (3)

Claims: 1. Process for the regeneration of deactivated catalysts which are suitable for carrying out reactions of the Fnedel-Crafts type and which are originally produced by reacting activated aluminum oxide, which optionally contains a hydrogenation-active metal from group VI a or VIII of the periodic table with Compounds of the general formula in which X and Y can be identical or different and are H, Cl, Br, F and / or SCl, or X and Y together are 0 or S, have been prepared under non-reducing conditions at 149 to 593 "C in such a way that chlorine is absorbed by the oxide without the formation of free chloride, characterized in that the catalysts freed from reactants are treated at 121 to 650 "C with an oxygen-containing gas and then chlorinated again with the compounds of the general formula given above under the conditions mentioned above. 2. The method according to claim 1, characterized in that the treatment with the oxygen; containing gas takes place at temperatures between 204 and 538 "C. 3. The method according to claim 1 and 2, characterized in that the Chlorination in the presence of catalyst materials containing platinum group metals is made at 149 to 371 "C.