DE2703521C3 - Process for the regeneration of coke-contaminated catalysts with simultaneous carefully controlled combustion of carbon monoxide - Google Patents

Description

The invention relates to hydrocarbon processing and, more particularly, to catalytic cracking processes. It relates in particular to a method for Regeneration of coke-contaminated cracking catalysts with carefully controlled> Combustion of carbon monoxide to carbon dioxide in the regeneration zone of a catalytic cracking process.

Regeneration methods in which a contaminated with coke catalyst in a regeneration zone i "is regenerated, represent a wide range of chemical or hydrocarbon processing technology. Particularly common regeneration methods for the regeneration of coke contaminated fluidizable cracking catalysts in the regeneration i ^r> tion zone a catalytic fluid or fluidized bed cracking process (hereinafter mostly referred to as fluidized bed cracking for the sake of simplicity). Until a few years ago, the prior art was primarily concerned with removing the greatest possible amount of - »coke from the spent catalysts while at the same time removing excessively large amounts to prevent temperatures, as they result from the conversion of carbon monoxide to carbon dioxide, within certain areas of the regeneration zone, par- 2 ^r> particular in the area where the catalyst is present in the dilute phase, so little catalyst for Shoo e the heat of reaction is present and consequently heat damage to cyclones or other separating devices can occur. An essentially complete conversion of carbon monoxide was prevented in conventional regeneration zones simply by limiting the amount of fresh regeneration gas flowing into the regeneration zone. Without the presence of sufficient κ oxygen to maintain the oxidation of carbon monoxide to carbon dioxide, afterburning cannot occur, of course, regardless of the temperature in the regeneration zone. Furthermore, the temperatures in the regeneration zone have generally been limited to less than about 675 ° C. by appropriate selection of the operating conditions in the hydrocarbon reaction zone or the fresh feed streams or the recycle streams or by combinations of these measures to thereby reduce the amount of coke consumed Catalyst and thus the amount of burned combustible material in the regeneration zone. The exhaust gas produced, which contained several percent by volume of carbon monoxide, was either blown directly into the atmosphere or used as fuel in a CO boiler downstream of the regeneration zone

The usual method for starting a catalytic fluidized bed cracking process, such as the 5ί A person skilled in the art in the field of the catalytic fluidized bed touch process is familiar was the Flow of fresh regeneration gas to the regeneration zone initially by hand in an amount rules, which for the maintenance of an essentially <> o Complete carbon monoxide conversion is not sufficient * and at the same time the regeneration zone temperatures are raised to a maximum value of around 675 ° C restrict. After reaching and regulating a usable steady state of the catalytic <> 5 fluidized bed cracking process, the flow rate of fresh regeneration gas was then normally through Instrument control in direct response to controlled a small temperature difference between the exhaust gas outlet temperature (or the temperature in the thin phase separation space) and the temperature of the dense bed in order to automatically maintain this correct flow rate of the fresh regeneration gas and preclude an essentially complete conversion of CO to CO ₂ anywhere within the regeneration zone. When the temperature difference increased beyond a predetermined temperature difference, indicating that a greater conversion of CO was taking place in the dilute phase, the amount of fresh regeneration gas was reduced in order to prevent an essentially complete conversion of CO to CO ₂ . This control method is e.g. B. in US-PS 31 61 583 and 32 06 393 described. This method results in a small amount of oxygen in the exhaust gas, generally in the range of 0.1 to 1 volume percent O ₂ , but makes essentially complete conversion of CO to CO ₂ within the regeneration zone impossible.

Until the introduction of zeolite-containing catalysts, there was only a relatively small economic incentive for an essentially complete conversion of CO to CO ₂ within the regeneration zone. However, the use of zeolite-containing fluidized bed cracking catalysts, which are more thermally stable and less prone to coke formation, and the use of higher temperatures in the hydrocarbon conversion zone have often made additional heat input into the fluidized catalytic cracking process necessary or desirable . B. from auxiliary fuel oil, in the regeneration zone or by using or increasing the extent of charge preheating in external charge preheaters. a feed preheater and a CO boiler, both of which have significant capital and operating costs. Catalyst regeneration processes described in the more recent state of the art have recognized the advantages of essentially complete conversion of CO to CO2 and recovery of at least part of the heat of combustion of the carbon monoxide, both within the regeneration zone, as examples of such regeneration processes are US Patents 38 44 973 and 39 09 392 called The advantages of such working methods are now recognized; such regeneration methods permit reduction or elimination of feed preheat, the elimination of carbon monoxide pollution without the need for external CO boilers, and, when operated in conjunction with modern design hydrocarbon reaction zones, improved yields of more valuable products.

Regeneration methods using CO conversion promoters or catalysts have already been reported; in conventional processes for the regeneration of fluidizable, such promoters or catalysts have been used with coke contaminated cracking catalysts. For example, in US Pat. No. 2,436,927

Fluidized catalytic cracking process described (1948) a physical mixture of separate particles of a cracking catalyst and separate particles of a support-containing CO oxidation catalyst in a dense phase region of a regeneration ^r> tion zone applied to a CO conversion to promote in the dense phase, and thereby a "post-combustion" to prevent in the dilute phase area of the regeneration zone. In the process described in US Pat. No. 3,354,136 (1968), a mixture of a cracking catalyst and a shape-selective crystalline aluminosilicate which contains an oxidation catalyst within its internal pore structure is used to control the CO ₂ / CO ratio in the regeneration zone without influencing the reaction taking place in the hydrocarbon reaction zone. In the process described in US-PS 38 08 121 Proceedings two separate catalysts are used of different particle size and composition, namely a Krackkata- 2 'lyst and a CO- Jxydationskatalysator, preferably supported in an m matrix material such as Aluminiumoxydkugeln and monoliths. Furthermore, the supported CO oxidation catalyst is kept within the regeneration zone, and it does not flow out of this zone to the hydrocarbon reaction zone, as does the cracking catalyst. Coke and carbon monoxide are subjected to oxidation in the regeneration zone to keep the CO content in the exhaust gas as low as to do as possible. j <>

Previous regeneration processes thus have CO oxidation promoters on one of the following two Ways used: (1) on separate particles of a matrix or carrier, the particles with the Are to be mixed with fluidized cracking catalyst, and (2) as part or component of the fluidized cracking catalyst itself, mixtures of cracking catalyst and Carrier-containing CO oxidation promoters tend to be uneven, which leads to a CO concentration in the Exhaust gas above permissible emission restrictions can result. The use of a cracking catalyst having any predetermined component as a component Concentration containing a CO oxidation promoter makes it difficult in any individual case present regeneration zone to bring about the optimal concentration of oxidation promoter necessary for the operating characteristics of this particular regeneration zone suitable or to achieve a special one Modification of a dependent procedural changer are required. w

By enticing the invention, a CO oxidation promoter is fed to the regeneration zone independently of the cracking catalyst, coke from the spent catalyst is oxidized to produce regenerated catalyst and essentially >> chen simultaneously converted carbon monoxide in the presence of the promoter and the regenerated catalyst within the regeneration zone to carbon dioxide. It can be a carbon monoxide oxidation promoter easily and precisely, in particular in this way if it is in a liquid, in the regeneration zone in quantities for controlling the CO concentration in the exhaust gas, for controlling a temperature within the regeneration zone or to control the amount of residual carbon on the f> 5 regenerated catalyst are introduced. The introduction of a CO oxidation promoter after the The process of experience is accordingly simpler, better and more economical than either using separate particles of a supported CO oxidation promoter together with a cracking catalyst or using a cracking catalyst, to which a CO conversion promoter has been added during the catalyst manufacturing run In addition, the method of the invention provides the operating personnel with an operating condition as a process variable which up to now has essentially been a fixed operating condition. Accordingly, the operation is carried out using the Method of the invention of increased operational flexibility and adaptability The invention is applicable to any existing or newly installed fluidized bed cracking process.

The invention is therefore based on the object of providing an improved method for regenerating a catalyst contaminated with coke with simultaneous carefully controlled combustion of carbon monoxide in a regeneration "}"::; and an operational implementation that makes a controlled Klenge exothermic heat of reaction available for the operation of the regeneration zone and reduces the amount of carbon monoxide in the exhaust gas, which does not have the above-mentioned and similar shortcomings of known working methods and is simple, reliable and economical to carry out In connection with this, the invention aims in a catalytic cracking process in which coke-contaminated cracking catalyst and oxygen-containing regeneration _{gas are fed to a regeneration zone maintained at coke oxidation conditions to produce a regenerated catalyst and an exhaust gas containing CO and CO 2} , indicating a mode of operation for utilizing the on-site and place taking place combustion of CO to CO2 for the control of the operation of the regeneration zone. In connection with this, the invention also aims in connection with a catalytic cracking process in which coke-contaminated cracking catalyst and oxygen-containing regeneration gas are fed to a regeneration zone maintained at coke oxidation bonds to generate a regenerated catalyst and an exhaust gas containing CO and CO2, the indication (1) of a mode of operation for Control of the CO concentration in the exhaust gas within a predetermined CO concentration range, (2) an operation for controlling a regeneration zone temperature within a predetermined temperature range and (3) an operation for controlling the concentration of residual carbon on the regenerated catalyst within a predetermined residual carbon concentration range .

The invention relates to a process for the regeneration of coke contaminated Catalysts with simultaneous carefully controlled combustion of carbon monoxide, which; through this is marked that one

(a) Catalyst contaminated with Kok. "into a Introduces regeneration zone,

(b) a carbon monoxide oxidation priority in the Regeneration zone regardless of the catalyst contaminated with coke in an amount that is suitable for Promotion of the combustion of carbon monoxide to carbon dioxide.

(c) oxygen-containing regeneration gas into the control regeneration zone in an amount sufficient to burn off

of coke from the coke-contaminated catalyst and sufficient excess to display Oxygen is chosen to produce the desired level of carbon monoxide combustion will initiate.

(d) a first portion of the oxygen-containing regeneration gas with the coke-contaminated catalyst in the regeneration zone under oxidation conditions, those used to remove coke from the coke contaminated catalyst and generate it a carbon monoxide containing exhaust gas are selected and to bring about a Combustion of carbon monoxide to carbon dioxide in the presence of the oxidation promoter suffice, converts and

(E) at the same time the exhaust gas and a second portion of the oxygen-containing regeneration gas with the Carbon monoxide oxidation promoter in the regeneration zone in the presence of regenerated Bringing the catalyst into contact with the oxidation conditions, and thereby (I) a controlled one Makes amount of exothermic heat of reaction available for the operation of the regeneration zone and (2) decreases the amount of carbon monoxide in the exhaust gas.

In connection with this, another embodiment of the invention relates to a method for the catalytic cracking of a hydrocarbon feed stream which is more contaminated with coke Cracking catalyst and oxygen-containing regeneration gas in one maintained at coke oxidation conditions Regeneration zone are passed, in the coke to produce a regenerated catalyst and a Carbon monoxide and carbon dioxide containing exhaust gas is oxidized, a way of working to exploit the on-site combustion of carbon monoxide to carbon dioxide for the control of the Operation of the regeneration zone provided, which is characterized in that one (a) the regeneration zone a carbon monoxide oxidation promoter regardless of the catalyst contaminated with coke in an amount sufficient to initiate and maintain carbon monoxide combustion in the regeneration zone is selected in the presence of the regenerated catalyst, and (b) then the amount of the oxygen-containing regeneration gas conducted to the regeneration zone to a value which stoichiometric to burn off the coke from the catalyst and to convert at least one Part of the carbon monoxide in carbon dioxide is sufficient, and thereby (1) a controlled amount exothermic Heat of reaction for the. Operation of the regeneration zone and (2) reduces the amount of carbon monoxide in the exhaust gas.

Further aspects and preferred measures of the invention relate to expedient embodiments with regard to carbon monoxide conversion promoters. the amounts of a carbon monoxide conversion promoter to be added, Working methods for the introduction of a carbon monoxide conversion promoter in the regeneration zone as well as the operating conditions: further information can be found in the following further explanation of the invention.

First, for the sake of clarity and better understanding of the method of the invention, several will be considered expressions used here defined.

The term "hydrocarbon reaction zone" denotes that part of a fluidized catalytic cracking plant in which a hydrocarbon feed stream with regenerated catalyst is brought into contact under cracking conditions to produce a mixture of fluidized catalytic cracked product components, coke contaminated (or spent) catalyst and any unreacted feed. Typical fluidized bed catalytic cracked product components as obtained after separation in facilities downstream of the hydrocarbon reaction zone are CrBrennbas, Cj- and C4-I ^; Actions, a Ben / .infrakiion, light circulatory oil and clarified sludge oil. After the product components have been separated off, at least part of the used catalyst is conveyed to the regeneration zone. The terms "catalyst contaminated with coke" or "spent catalyst" are interchangeable and refer to catalyst produced by a hydrocarbon conversion zone ■ -> ■. has been withdrawn due to decreased activity due to coke deposits. End-consumed analyzer flowing into the regeneration zone may contain a few tenths up to about 5 percent by weight of coke; typically, in fluid catalytic cracking operations, the spent catalyst will contain from about 0.5 to about 1.5 weight percent coke.

The designation »regeneration zone« identifies the part! flor catalytic fluidized bed cracking plant ", in a regeneration gas containing oxygen and at least part of the spent catalyst is introduced and in which at least part of the coke of the used catalyst dur '"' ·, (> \ ydation is removed to generate regenerated catalyst and an exhaust gas containing CO2 and CO. "Regenerated catalyst" is a catalyst from which at least a portion of the coke is oxidized has been removed. Regenerated catalyst as produced using the process of the invention generally contains less than about 0.3 weight percent Coke and especially from about 0.01 to about 0.15 weight percent coke. Under the expression "regeneration gas", as it is used here, is to be understood in the general sense as any gas that is associated with the Catalyst is to be brought into contact or that with catalyst in the regeneration zone in contact has stood. The expression »oxygen-containing regeneration gas« denotes a regeneration gas, containing free or unbound oxygen, e.g. B. air or oxygen enriched air or one Air which is deficient in oxygen and which flows into the regeneration zone to prevent coke burning of the spent catalyst and to enable a conversion of CO. The expression "exhaust gas" refers to regeneration gas that has been in contact with catalyst within the regeneration zone and flows out of the regeneration zone. The exhaust gas contains nitrogen, free oxygen and carbon monoxide. Carbon dioxide and water. Because CO and COr concentrations for performing routine calculations be used for the catalytic fluidized bed cracking process and since the CO represents a potential fuel that is inside the regeneration zone or in an external CO boiler or, if necessary, can be incinerated in both ways, and there are also mostly restrictions with regard to air pollution through the emission of CO, the exhaust gas is normally caused by the Concentration of CO and CO2 or by the

Characterized by the molar ratio of CCVCO. Depending on the operating conditions used in the regeneration zone, in particular the amount of oxygen-containing regeneration gas passed into the regeneration zone, the concentrations of CO in this exhaust gas can be over a wide range from a few hundred parts-per-million or even below up to about 15 percent by volume or still vary dv over and the concentration of CO2 can be in a range from about 5 percent by volume to about 20 percent by volume. When the regeneration zone is operated under conditions to largely prevent controlled oxidation of carbon monoxide within the regeneration zone, the concentrations of CO and CO ₂ are approximately the same, both within the range of about 7 to about I ^r > volume percent, and the COo / CO Molar ratio is then in the range from about 0.8 to about 1.5. If the regeneration zone is operated under conditions to achieve a partially complete oxidation of CO, the concentration of CO is lower than that of CO 2 and, in particular, the CO 1 / CO ratio will normally be about 1.5 to about 100 . When the regeneration zone is operated under conditions to achieve substantially complete combustion of CO within the regeneration zone, the concentration of CO will normally be less than about 1000 parts-per-million, preferably less than 500 parts-per-million, and the CO ₂ / CO molar ratio is greater than about 100.

The terms "dense phase" and "dilute phase" s ^: nd terms used in the field of fluidized bed catalytic cracking for the general designation of catalyst densities in different parts of the regeneration zone or the hydrocarbon reaction zone. The boundary density is not clearly defined. In the present documents, the term "dense phase" is intended to designate areas within the regeneration zone where the catalyst density is greater than about 80 kg / m ¹ ; the expression "dilute" does not exist in areas where the catalyst density is less than about 80 kg / m ³ . Usually the density of the dense phase area is in the range of about 80 to 560 kg / m ¹ or more and the density of the dilute phase area is well below 80 kg / m ³ and in the range of about 1.6 to about 80 kg / m ¹ . Catalyst densities in regeneration zones are usually determined by measuring pressure or column differences along pressure sensors built into the vessels and arranged at known distances from one another.

The term "post-combustion" is generally _{understood in the art to mean the unintentional, uncontrolled oxidation of CO to CO 2} in the dilute-phase area of the regeneration zone or the exhaust pipe, where little catalyst is available to act as a heat absorbent. Since the heat of reaction of the CO oxidation is very exothermic, it is about 2420 Kcal / kg oxidized CO, post-combustion can accordingly lead to severe damage to the catalyst separation devices arranged in the dilute phase. In general, afterburning is shown by a rapid rise in temperature, and it occurs during periods of unsteady operating conditions or "fluctuations" or "disturbances" in the process sequence. It is accordingly usually of a short duration until a steady operating state is brought about again.

In contrast to post-combustion, the terms "controlled conversion of CO" or "controlled oxidation of CO" are intended to mean the deliberate, controlled and sustained oxidation of CO in the presence of sufficient catalyst to absorb at least part of the heat of reaction, so that at least a part of the Heat of reaction is obtained and damage to equipment in the regeneration zone is excluded. Depending on the operating conditions employed, the controlled oxidation of CO may be partially complete or substantially complete. "Partially completed" is intended to mean that the CO concentration in the exhaust gas has been reduced so far. that the CO ^ CO molar ratio of the gas is in the range of about 1.5 to 100. "Substantially complete" conversion of CO is intended to mean that the CO concentration of the gas has been reduced to such an extent that the CO ₂ / CO molar ratio is greater than otw; i 100. Tynisrhrwn results in essentially complete CO conversion> .u CO concentrations less than about 1000 parts-per-million and preferably less than about 500 parts-per-million.

The terms “CO conversion promoter” or “CO oxidation promoter” or simply “promoter” are intended to denote a substance that catalyzes _{the oxidation of CO to CO 2.} With a CO conversion promoter, the kinetic rate constant for the oxidation of CO to CO _{2 can} usually be increased 2 to 5 times, or even much more. A faster rate of CO conversion can thus be achieved under conversion conditions in the presence of a CO conversion promoter than is the case with the same conversion conditions without the promoter. Conversely, the same CO conversion rate can be achieved under less severe conversion conditions, e.g. In terms of temperature, than would be required without the CO conversion promoter.

The amount of CO conversion promoter introduced into a regeneration zone can be expressed are considered to be the amount that is required to make a desired change of a variable or it can be expressed in terms of the circulating catalyst inventory or the catalyst circulation rate or the replenishment rate for fresh cracking catalyst or optionally in in relation to a unit of quantity of the charge. In the present documents, the amount of promoter usually expressed as the amount required to make a desired change in a variable, such as the temperature, the CO concentration or the residual carbon content, or they is reported as parts-per-million by weight of circulating Catalyst inventory. The expression "circulating catalyst inventory" denotes the amount of the cracking catalyst in the fluidized catalytic cracking process, which is obtained from the regeneration zone can be circulated to the hydrocarbon reaction zone and back again. She makes a difference from the total cracking catalyst inventory as there is usually some proportion of the total catalyst inventory that is not available for circulation, e.g. B. the proportion of the total stock, which is typically located in the cone section of the regeneration zone under the pipe grille.

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Taking these definitions into account, today's typical operating modes of catalytic fluidized bed cracking are briefly considered with special consideration of the operation of the regeneration zone. Modern fluid catalytic cracking operations have achieved a significant reduction in coke yield through the widespread use of crystalline aluminosilicate cracking catalysts and the use of short carbon-hydrogen catalyst contact times, for example through riser cracking. While this led to higher yields of more valuable gaseous and liquid products, it also reduced the amount of solid combustible substance available for combustion in the regeneration zone to meet the heat balance requirements of the process. More recent methods of the prior art have recognized that by the combustion of prvpiicrtf * nt Γ ^ Ο innprhtilK / Ipr RpnpnArolinnc / onp - _. _o .... _{H. uu} ~. . .. _o * .. _v ..... *.>. w .. _u , ·. *

and recovering at least a portion of the exothermic heat of reaction a sufficient amount of heat for the Heat balance requirements imposed by a wide range of operating conditions and feed materials brought about is available. Such CO combustion also has further reductions in the Coke yields and increases in the yields of gaseous and liquid products as well as a Reduction or omission of the feed preheating allows and at the same time without the Necessity to arrange an external CO boiler. Air pollution problems from CO emission in eliminates the atmosphere.Typical modern regeneration zones have a single cylindrical vessel, the one diluted phase in the upper section of the vessel, in which there are cyclone separators, and contains a dense phase in the lower portion of the vessel. Used catalyst occurs at the Side or bottom of the vessel and fresh regeneration gas is fed in at the bottom of the vessel and by a pipe grid or an array of perforated plates within the dense phase distributed. Coke is produced with the production of regenerated catalyst and exhaust gas containing CO and CO2 oxidized and CO can in the presence of a sufficient amount of catalyst for recovery at least part of the heat of combustion can be further oxidized. Containing entrained catalyst Exhaust gas flows upward out of the dense phase into the dilute phase where cyclone separators Separate entrained catalyst and return to the dense phase and the separated off gas forward from the regeneration zone. To be limiting or limiting points of view for the Operation of the regeneration zone includes the performance of the air blower, limits of load capacity of the cyclone separator (s). Limitations on the emission of CO and entrained Particulate matter from the exhaust gas and restrictions on container temperatures. While the Regeneration zone, the operating staff has primarily the extent of the catalyst regeneration that Regeneration zone temperatures and the concentration of CO and entrained particles in the exhaust gas observe and monitor closely. It is typical refinery practice to periodically take samples of the regenerated To remove the catalyst and use known methods for their residual carbon content to be analyzed as a measure of the extent of catalyst regeneration and an indication of cracking activity of the regenerated catalyst. The regeneration zone temperatures are determined, usually by means of thermocouples, routinely measured and recorded to detect changes in operations and ensure that the metallurgical restrictions in place on the regeneration vessel are not be crossed, be exceeded, be passed. Furthermore, it is typical practice to periodically or continuously take samples of the exhaust gas and its concentrations of CO, O2, Analyze CO2 and particulate matter. The gas analyzes can be based on any known Methods are carried out, e.g. B. Orsat analysis, gas chromatographic methods and wet spectroscopy Methods. Particulate matter can be determined by opacity measurements or other known Analysis methods are determined. Gas analysis results can be used for calculation, through carbon-nitrogen-oxygen Balance, such data as Kokszu composition, coke burn rate, demand for oxygen-containing regeneration gas, heat of combustion of the coke and the amount of CO that is in an outer CO boiler or in the regeneration zone of the catalytic converter Fluidized bed cracking process or, if necessary, can be incinerated in both, used will. Before the exhaust gas can be vented directly into the atmosphere, the operating personnel must also know the concentrations of CO and particulate matter in the exhaust gas to determine if that Exhaust gas meets local air pollution restrictions with regard to CO emissions. The concentration of Oj in the exhaust gas is important to ensure that the amount of oxygen-containing regeneration gas is sufficient to maintain the desired extent of CO combustion, be it a partially completed or essentially complete CO combustion, on the other hand but is not supplied in such a large excess that it places an unnecessary load on the fan capacity for the oxygen-containing regeneration gas.

A feature of the method of the invention in all of its embodiments is that a CO oxidation promoter introduced into the regeneration zone independently of the cracking catalyst will. Useful carbon monoxidation promoters include Group Ib, Hb, Via, VIIa, and Metals Viii of the Periodic Table of the Elements and Compounds of that. Chromium, nickel, iron are representative examples. Molybdenum, cobalt, copper, zinc, Manganese and vanadium and compounds thereof are mentioned. Preferred CO oxidation promoters are the noble metals and compounds thereof, since it was found that only very small amounts of these promoters are necessary to achieve the desired results. Under the designation »precious metals« are in the usual way the metals gold, silver, mercury, platinum, palladium, iridium, rhodium, and ruthenium Understanding Osnium. The promolor can be added to the regeneration zone in the form of a solid be e.g. B. as powder, chips, pellets or agglomerates, but preferably the promoter placed in a liquid for ease of handling and control. The the Promoter-containing liquid can be continuously or intermittently by means of known media flow and control devices are added.

For example, the liquid containing the promoter can be extracted from a cylinder or from a pressure bottle be squeezed out by means of pipe connections to an auxiliary fuel oil nozzle or a pressure sensing nozzle guided probe is connected, the inflow through a located in the connecting line Valve is controlled. The liquid can also be in a controlled by a small positive displacement pump Amount / time can be pumped from a container into the nozzle or probe. The CO conversion promoter can be distributed in the liquid in the form of a colloidal dispersion or suspension or it can be in the Be liquid soluble. Particularly preferred oxidation promoters are noble metals or compounds thereof soluble or dispersible in water or a liquid hydrocarbon. To suitable water-soluble metal compounds include the metal halides, preferably chlorides, nitrates, amine halides, Oxides, sulfates, phosphates and others

2-ethyl-l-hexanol (-70 ⁰ C). I-heptanol (-34.6V). 4-heptanol (-41.5 ° C) and I-octanol (-16.4 ° C).

As already mentioned, solutions are particularly suitable of a CO oxidation promoter that have freezing points of about -34 ° C or below, so that they even at the location of a plant possibly occurring coldest temperatures are still liquid. Accordingly, particularly preferred solvents are the solvents that contain chloroplatinic acid or chloropalladic acid solutions with the desired Freezing points of -34 "C or below result. Suitable solvents here are also alcohols the group of saturated aliphatic alcohols with 2 to about 8 carbon atoms per molecule and Freezing points of -34 ° C or below Examples of this are given in the list above listed, with the exception of 2,3-dimethyl-2-butanol, 2-methyl-2-butanol and I-octanol, as these are three Alcohols do not have freezing points of 34 "C or

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Other water-soluble compounds are chloroplatinic acid, palwdic acid, palladium chloride, ruthenium tetrachloride, rhodium trichloride, rhodium nitrate and osmium trichloride. Alternatively, a liquid hydrocarbon containing an oil-soluble or oil-dispersible CO oxidation promoter can be fed to the regeneration zone. Suitable liquid hydrocarbons include the hydrocarbons normally liquid at atmospheric temperatures and pressures, such as. B. Heavy gasoline and light cycle oil. Oil-soluble or oil-dispersible compounds include, in particular, metal diketonates, carbonyls, metallocenes, olefin complexes, acetylene complexes, alkyl or aryl phosphine complexes and carboxylates. Specific examples of such compounds are platinum acetylacetonate, palladium acetate, palladium naphthenate. Trijodiridium (III) -tricarbonyl and (π, cyclopentadienyl) - (ethylene) -rhodium (I) called. Of the noble metals and their compounds, platinum and palladium and compounds thereof, particularly water-soluble compounds, are preferred because they are usually more accessible than compounds that are oil-soluble or oil-dispersible. Chloroplatinic acid and palladium acid are particularly preferred water-soluble platinum and palladium compounds.

In order to ensure a broader usefulness in technical application, however, solutions of a CO oxidation promoter with a freezing point of ⁰ ° C. or below are often preferred, so that they are still liquid even at the colder temperatures that can occur at the site of a plant. Solutions with freezing points of about -34 ° C. or below are particularly favorable, so that they are still liquid even at the coldest temperatures that can occur at the location of a plant. Solvents which yield with chloroplatinic acid or chloropalladic acid solutions, the freezing point of 0 ⁰ C or below, alcohols from the group of saturated aliphatic alcohols having 2 to about 8 carbon atoms per molecule and freezing points of from ⁰ ° C or below are. Examples of such alcohols, together with their freezing points, are: methanol (-98.7 ⁰ C), ethanol (-112 ⁰ C). 1-propanol (- 127 ° C), 2-propanol (- 85.8 ° C), 1-butanol (- 89.2 ^C C). 2-butanol (-89 ⁰ C), 2,3-dimethyl-2-butanoi (-14 ⁰ C). 2-methyl-2-butanoi (-i4 ⁼ C), 2-methyl-2-butanoi (-11.9 ⁰ C), 1-pentanol (-78.5 ° C). 1-hexanol (-51.6 ° C).

In addition to a freezing point of - 34 ° C or below, the solutions of the preferred CO oxidation promoters chloroplatinic acid and chloropalladic acid should also be chemically stable, o that no chemical change - indicated by the appearance of a further liquid phase or a solid phase - during the period in question Storage periods occurs. In order to be on the safe side with regard to unfavorable storage conditions that may occur, such solutions should be chemically stable for a period of 30 days at a temperature of 63 ° C. Some of the saturated aliphatic alcohols mentioned above, the resulting solutions, which satisfy the preferred freezing protocol of -34 ⁰ C, no solutions for 30 days were at 63 ° C were chemically resistant. Methanol, 2-propanol, 2-butanol and 2-methyl-2-propanol yielded, for example, chemically resistant wnren no solutions for 30 days at 63 ⁰ C. Furthermore, some customary freezing point depressants for water, such as ethylene glycol or propylene glycol, meet the desired freezing point specification, but they do not meet the desired requirements with regard to chemical stability. Solvents that gave solutions that met both the freezing point specification of -34 ° C and the chemical stability specification with no noticeable chemical change after 30 days at 63 ° C were alcohols from the group of saturated aliphatic primary alcohols having 2 to about 8 carbon atoms each Molecule and freezing points of -34 ° C or below. These solvents are therefore the preferred solvents for preparing the solutions. 1-butanol and 2-ethyl-1-hexanol are particularly preferred. In general, it was found that, with the exception of methanol, the chemical resistance of the solutions was best when the solvent consisted of a saturated aliphatic primary alcohol and was inferior when the solvent was formed from a saturated aliphatic secondary or tertiary alcohol. Preferably, these saturated aliphatic primary alcohols having 2 to about 8 carbon atoms per molecule and freezing points of -34 ° C. or below are used in the pure, undiluted state with chloroplatinic or chloropalladic acid. Preferred concentrations of chloroplatinic or chlorodalladic acid in the solution are

Concentrations corresponding to about 0.01 to about 10 percent by weight Pt or Pd, with concentrations from about 0.01 to 5 percent by weight of Pl or Pd are particularly preferred.

To best make optimal use of the very small amounts of promoter required to ensure, in the process of the invention, the addition of the promoter to the regeneration zone limited. By feeding the promoter directly into the regeneration zone, where the CO oxidation takes place, there is a virtually instantaneous response, so that a controlled amount Exothermic heat of reaction made available for the operation of the regeneration zone and the concentration of carbon monoxide in the exhaust gas is reduced. The CO conversion promoter can be used in the dense Phase or are introduced into the dilute phase of the regeneration zone. Albeit the promoter on several feed points can be introduced, it has been found that when using only a single ■ Feed point satisfactory results can be achieved. The typical regeneration zone vessels have a number of pressure sensors and auxiliary fuel oil nozzles, one or more of which as Feed points can serve; accordingly there is only: a very slight modification of the vessel itself required before the method of the invention can be used.

In one embodiment, the invention provides a mode of operation for the regeneration of coke-contaminated catalyst with simultaneous carefully controlled combustion of carbon monoxide. In this embodiment of the process, the coke contaminated catalyst is introduced into the regeneration zone and the CO oxidation promoter is fed into the regeneration zone independently of the coke oxidation. impure catalyst in one on the desired promotion of the combustion of CO to CO? brought in a coordinated amount. The amount of promoter added corresponds to about 0.1 to about 25 parts-per-million by weight of the circulating catalyst inventory, based on elemental metal, and is preferably in the range of about 0.1 to about 15 parts-per-million by weight of the circulating catalyst inventory. Oxygen-containing regeneration gas is then introduced into the regeneration zone in an amount which results in sufficient excess oxygen to bring about the desired extent of CO combustion. In particular, this amount of oxygen-containing regeneration gas corresponds to about 10 to about 17 kg of air per kg of coke that enters the regeneration zone per unit of time, depending on whether the CO combustion is to be partially complete or essentially complete. It has been found that it is important to introduce the promoter first into the regeneration zone and then the oxygen-containing regeneration gas so that a smooth, controlled catalytic conversion of CO can be initiated from the start and the possibility of post-combustion is suppressed as far as possible. If this amount of <saiierstoffhaltigem regeneration gas is first introduced into the regeneration zone and the promoter is added thereafter, there is a risk that initially a post-combustion instead of the desired controlled conversion of CO is introduced in the presence of promoter and regenerated catalyst. A first part of the oxygen-containing regeneration gas is then reacted with the coke-contaminated catalyst in the regeneration zone under oxidation conditions which are selected to remove coke from the catalyst and to generate a CO-containing exhaust gas and which are sufficient to burn CO to CO ₃ in the presence of the oxidation promoter bring about. The oxidation conditions include, in addition to the presence of the oxygen-containing regeneration gas discussed above, temperatures within the range of about 590 to about 790 ° C and a pressure within the range of about atmospheric to about 4.5 atm. Under such conditions, coke oxidation occurs essentially spontaneously.

Essentially simultaneously, the exhaust gas and a second part of the oxygen-containing regeneration gas with the CO oxidation promoter in the the previously indicated oxidation conditions brought into contact, creating a controlled amount exothermic heat of reaction made available for the operation of the regeneration zone and the amount of CO in the exhaust gas is reduced.

The amount of oxidation promoter introduced into the reduction zone can be selected in accordance with the achievement of certain desired results, e.g. B. a desired concentration of CO in the exhaust gas or a desired extent of the catalyst regeneration or a desired temperature of the regenerated catalyst or a desired regeneration zone temperature. When adding the required amount of the CO oxidation promoter to achieve such a result, the promoter is usually added gradually in small portions and the relevant dependent variable - be it the CO concentration or the residual carbon content on the regenerated catalyst or a temperature - is measured and compared to the target result to determine whether an additional portion of the CO oxidation promoter is needed. If, after a small portion of the promoter has been introduced into the regeneration zone, the measured concentration of CO in the exhaust gas or the concentration of residual carbon on the regenerated catalyst or the temperature of the regenerated catalyst or the relevant regeneration zone temperature is not yet within the predetermined range, a second portion is used of the promoter, ie a further increment of the promoter, and, if necessary, further increments are added until the measured variable falls within the predetermined range. The addition of the promoter in several small increments, in each case over a relatively short period of a few minutes to a few hours, allows the operating personnel more precise control and monitoring of the operation of the regeneration zone in order to achieve the desired result. If the protnotor is added in several increments, the total amount of the promoter is within the ranges given above. When the variable to be controlled is a dilute phase temperature. r. B. an exhaust gas temperature, the CO-Oxydalionspromoior can be introduced together with a diluent gas to enable the temperature to be controlled below a predetermined value. Oxygen-containing regeneration gas is normally used as the dilution gas. As soon as the measured variable is within the predetermined range for this variable

909 614/457

before or below, the promoter becomes continuous or added intermittently to the extent necessary to keep the measured variable within of the predetermined range. The amounts of promoter required to produce a variable ί Keeping it within a predetermined range can change from plant to plant, and so do they are best determined by observation and experience in the operation of the particular facility it has however, it has been shown that the amount of promoter targeting i < > Average daily base required to maintain a variable within a predetermined range is, about 0.005 to about 10 parts-per-million by weight of the circulating catalyst stock, based on elementary metal. ι '■

Other embodiments of the process include particular independent control methods for use after the fluidized catalytic cracking process has been initially started up and after a useful steady state operation of the process has been achieved. In particular, the invention provides in one embodiment in a process for the catalytic cracking of a hydrocarbon feed stream in which coke-contaminated catalyst and oxygen-containing regeneration gas are passed into a regeneration zone maintained at oxidation conditions and containing coke to produce regenerated catalyst and a CO2 and CO Exhaust gas is oxidized, a mode of operation for controlling the CO concentration in the exhaust gas J <> within a predetermined CO concentration range. In another embodiment, the invention provides a method of operation for controlling a regeneration zone temperature within a predetermined range in such a method. In yet another embodiment, in such a method, the invention provides a mode of operation for controlling the concentration of residual carbon on the regenerated catalyst within a predetermined range. Such Steuerungsmetho- the w can be applied independently of the operating personnel. For example, in one case the operational management may be primarily interested in keeping the CO concentration in the exhaust gas within a predetermined range, and if the temperatures to be expected do not pose any difficulties with regard to metallurgical aspects of the regeneration zone, it will change the regeneration zone temperatures and the degree of regeneration that result in controlling the CO-con- w concentration, allow. In another instance, management may be primarily concerned with regeneration zone temperatures in view of metallurgical restrictions. According to one embodiment of the invention, it can then keep a regeneration zone temperature within a predetermined range and it will accept the CO concentration of the exhaust gas and the degree of regeneration that result from this control method. In each of these control methods, the m> CO oxidation promoter is first introduced into the regeneration zone and then oxygen-containing regeneration gas is fed to the regeneration zone in an amount that is stoehiometrically sufficient to convert at least part of the carbon monoxide into carbon dioxide n ~> . As already mentioned, the order in which they are fed is important in order to avoid the risk of afterburning / ti. At least a portion of the carbon monoxide is then converted under conversion conditions including the presence of the CO oxidation promoter and regenerated catalyst to produce exhaust gas containing CO ₂ and CO. The conversion conditions include a temperature within the range of about 590 to about 790 ° C. and a pressure within the range of about atmospheric pressure to about 4.5 atm. Depending on the control method used, the exhaust gas is then analyzed to determine the actual CO concentration and the latter is compared with the CO concentration range to be maintained, or a regeneration zone temperature is measured and compared with the specified regeneration zone temperature range, or a regenerated catalyst is used to determine the actual The residual carbon concentration is analyzed and the latter is compared with the residual carbon concentration range to be observed. The promoter is then supplied to the regeneration zone in such quantities that either the CO concentration or a regeneration zone temperature or the residual carbon concentration are kept within their specified ranges. The amount of promoter initially supplied to the regeneration zone is preferably added in small increments, as previously explained, until the desired result is achieved. The sum of these increments corresponds to about 0.1 to about 25 parts per million by weight of the circulating catalyst inventory, based on elemental metal , and preferably ranges from about 0.1 to about 15 parts per million by weight of the circulating catalyst inventory. The average daily amount of promoter required to maintain a measured variable within a given range is typically from about 0.005 to about 10 parts-per-million by weight of the circulating catalyst inventory, calculated as elemental metal.

The type of cracking catalyst used in fluid catalytic cracking processes employing the The method of the invention is used is not of critical importance, rather any Types of common cracking catalysts employed or for use in the fluidized catalytic cracking process be provided, both the amorphous catalysts and crystalline aluminosilicate catalysts as well as mixtures of the two types. Of the two general types of cracking catalyst, the Catalysts comprising crystalline aluminosilicates because of the reduced coke yields and the increased yields of gaseous and liquid products compared to amorphous catalysts generate, preferred. Since when using the method of the invention carbon monoxide as a fuel in addition to the coke is oxidized within the regeneration zone and at least part of the heat the CO combustion is recovered within the regeneration zone, the cracking section of the catalytic Fluidized bed cracking process can now be as selective for more valuable products as that Allow operating conditions of the hydrocarbon conversion zone and cracking catalyst. the Operating conditions of the hydrocarbon conversion zone accordingly become maximum as a result Yields of gaseous and liquid products are chosen and they usually include a temperature within the range of about 420 to about 600 ° C, a pressure within the range of about

Atmospheric pressure up to about 4.5 atm, a catalyst / O | ratio from about 3 to about 20 and one Hydrocarbon residence time in contact with the catalyst from about 1 to about 30, and preferably from about 1 to about 10 seconds. The case of catalytic)> Fluidized bed cracking processes employing the process of the invention do not need to differ from the input materials used in operations without Application of the method of the invention can be employed, and they can be any conventional Hydrocarbon feedstocks include, e.g. B. Heavy gasoline, gas oils, light and heavy distillates, Residual oils and the like

The method of the invention is described below at i> Hand of examples and comparative experiments further illustrated, but it is also not based on that specified particular promoters, concentrations of promoters, operating conditions or methods limited to the introduction into the regeneration zone.

Fluidized nitrogen; the latter entered at the bottom of the vessel. At the same time the device was on heated to a temperature of 593 ° C. At a specified time, the nitrogen was replaced by air replaced and thereby initiated the oxidation of the coke. The exhaust gas from the vessel had that in the CO concentrations given in Table I below, determined by the chromatographic device at different times after the introduction of air:

Table I.

Regeneration zone of the experimental facility, experiment 1,

No CO oxidation promoter
CO concentrations in the exhaust gas

• 40

example 1

This example describes investigations carried out in a semi-industrial test facility the processes in the regeneration zone of a catalytic! Fluidized bed cracking plant, with the investigations were carried out to determine the effectiveness of adding a liquid that was low Contains concentrations of certain promoters, to the regeneration / one of the catalytic fluidized bed cracking plant for the purpose of reducing the concentration of CO in the exhaust gas. The J investigations were performed using a vertical "tubular vessel, the upper end of which with a porous stainless steel filter was provided to thereby remove the catalyst sample placed in the vessel to be kept inside the vessel and its lower part during the sequence of operational measures End of an inlet direction for the fluidizing medium, nitrogen or air, and an introduction device for the liquid containing the promoter. Means were also provided to open the vessel a constant temperature was heated, and a chromatographic device was used for sampling and analysis of the exhaust gas from the vessel for CO, CO2 and Oj, so that in each case the current composition of the gas for the purpose of determining the reduction in the CO concentration could be determined.

Each run was carried out with a 500 g sample of spent zeolite-containing cracking catalyst, the containing about 0.9 weight percent coke. The coke was deposited on the catalyst by passing a gas oil feed through the cleanly regenerated catalyst in a hydrocarbon reaction zone of semi-industrial experimental scale, which under standard operating conditions with a predetermined Sequence of work measures operated had been enforced.

In experiment 1, no liquid containing promoter was introduced into the vessel during the operating sequence; the experiment was carried out to obtain a minute basis for comparison for further experiments in which h> the method of operation according to the invention was used. A 500 g sample of the spent catalyst was poured into the vessel and mixed with

Time, CO in the dry CO2 / CO- Minutes Exhaust, % relationship 1 2.4 3.09 2 3.5 3.00 3 5.0 2.86 4th 6.0 2.58 5 5.7 2.96

As can be seen from the values, the CO 2 / CO ratio remained in the fairly narrow range of about 2.5 to about 3.0 during the experiment.

Experiment 2 was carried out in the same way as experiment 1, with the exception that 15 seconds after switching the fluidizing nitrogen to the supply of air and while an increase in the CO concentration was observed, 30 ml of dilute chloroplatinic acid solution (H ₂ PtCl ₆ ) were injected into the vessel. The solution was prepared by diluting chloroplatinic acid containing about 28.6 weight percent Pt with distilled water to form dilute chloroplatinic acid containing 0.1 mg Pt / ml. This amount of chloroplatinic acid corresponds to about 6.0 parts-per-million by weight of the catalyst sample calculated as metallic platinum. The instantaneous readings from the chromatograph indicated that the CO concentration was now decreasing. In the course of the experiment, the exhaust gas had the following compositions:

"Table Il

Regeneration zone of the experimental facility, experiment 2,

_{h ()} Dilute chloroplatinic acid, 0.1 mg Pt / ml
CO concentrations in the exhaust gas

CO in the dry Exhaust, %

1.7

coyco-

Relation

9.3 > l00 > 100

The carbon monoxide concentrations are essential lower, and the COj / CO ratios are much higher than the corresponding values in Experiment 1 for the same time periods. To see how quickly that If platinum loses its effectiveness in reducing the concentration of i CO, it has been regenerated Catalyst from experiment 2 for further circuits in an experimental hydrocarbon reaction zone and then used in the regeneration zone without the addition of promoter. After the first in three more loops through the hydrocarbon reaction zone and the regeneration zone was at essentially no CO formation was observed after coke combustion, but at the beginning of the fourth cycle a small amount of CO was present in the exhaust gas, ιί however, this amount was considerably less than the amount in Experiment 1 which had no promoter was used.

The same procedure was used with a new 500 g catalyst sample for Experiment 3, with the exception that a more dilute solution is used and the liquid containing the promoter was added to the vessel immediately before the fluidizing nitrogen was switched to air. In this experiment, 25 ml of the more dilute chloroplatinic acid, equivalent to about 0.5 Parts-per-million by weight of catalyst based on metallic platinum, placed in the vessel. The solution was prepared by diluting a portion of the solution used for experiment 2, the 0.1 mg jo Pt / ml, with distilled water to form a more dilute chloroplatinic acid solution with a Content of 0.01 mg Pt / ml. The CO concentrations in the exhaust gas were as follows:

Table III

Regeneration zone of the experimental facility, -to Attempt 3,

Dilute chloroplatinic acid, 0.01 mg Pt / ml
CO concentrations in the exhaust gas

Time.
Minutes

CO in the dry
Exhaust, %

CO2 / CO ratio

• 4

0.6

20.3
> 100
> l00

Although the reduced amount of promoter used in this experiment produced results which are comparable to the results obtained in experiment 2 with a higher promoter concentration were obtained, the regenerated catalyst apparently lost much of its promoter effectiveness quite quickly, since in subsequent cycles the presence of some CO during the regeneration stage was established. After three cycles the catalyst apparently produced about two thirds as much CO as was generated during experiment 1 without the addition of promoter.

In experiment 4, 25 ml of a solution of chloropalladic acid in water containing 0.1 mg of Pd / ml

W) contained, corresponding to about 5 parts by weight per million of the analyzer sample, calculated as Pd metal, injected into the vessel 15 seconds after switching from the fluidizing nitrogen to air, thereby initiating the combustion. The CO concentration in the exhaust gas fell to less than 0.2 percent by volume within two minutes.

Example 2

This example describes the behavior of the regeneration zone of a large-scale fluid catalytic cracking process shortly after the introduction of small amounts of a CO oxidation promoter containing liquid according to the method of the invention, with no other operational changes were made.

The catalytic one used for the investigation Fluidized bed cracking plant processes about 124 mVh of a mixture of Veku'im and coker gas oils and had a circulating catalyst inventory of approximately 54,500 kg of zeolite-containing catalyst. the System was brought into a constant operating state under typical operating conditions, without efforts to reduce the CO concentration partially or essentially completely were directed in the exhaust gas and without the presence of a CO conversion priority in the regeneration zone. A set of pertinent operating conditions of the process, prior to feeding a promoter to it the regeneration zone are summarized in Table IV below.

Then 2 liters of a solution of chloroplatinic acid in water were pressed out of a cylinder into the regeneration zone within a period of 2-3 minutes, by a nozzle located in the regeneration zone to determine the density. The diluted chloroplatinic acid solution was prepared by diluting 61.4 g of a concentrated chloroplatinic acid solution containing 28.637 weight percent Pt to 2 liter volume using distilled. Water. The introduction of this amount of solution into the regeneration zone means a promoter supply corresponding to about 032 parts by weight per million circulating catalyst inventory, based on metallic platinum. The regeneration zone responded almost immediately to this addition; the CO concentration in the exhaust gas decreased to about half the concentration before the introduction of the solution and the temperature of the dense phase of the regeneration zone rose by about 25 ^° C. above the temperature before the introduction of the solution. No other operational changes were made to the process. A summary of the operating conditions after this first addition of solution can also be found in Table IV.

Several hours later a smaller solution menu, the promoior corresponding to about 0.13 Parts-per-million weight of circulating catalyst inventory based on metallic Pt. in the Regeneration zone introduced in the same way as the first addition. Except for the addition of the promoter no other operational changes were made to the procedure. A summary of the Operating conditions shortly after this second addition can also be found in Table IV below.

Table IV

Response of the regeneration zone of a large-scale catalytic fluidized bed cracking plant on the addition of promoter selected operating conditions

Beginning, Towards Towards without pro giving of giving of molor admittedc 0.J2 wt. 0.13 Ciew Share each Share-each- - - ■ - million inillioii Temperatures, "C
Regeneration / one, dense phase 655 681 713 Regeneration zone, dilute phase 661 687 717 Regeneration zone, exhaust gas 667 678 703 Hydrocarbon reaction zone 510 511 511 United loading 328 328 329 Exhaust / .usumnierisei / .urig. VOi .- "/ o CO 10.5 5.9 1.4 CO, I0.S 12.8 17.1 O ₂ 0.0 0.0 0.0 COj / CO ratio 1.03 2.17 12.2 Remaining carbon on the regenerated 0.30 0.16 0.06 Catalyst, wt .-% Fresh delivery feed, mVh 124 124 Return material admixture. m "h Il Il 11th Air supply, mV. Second 15th 15th 15th

As can be seen from the values in Table IV, the CO concentration in the exhaust gas increased from 10.5 percent by volume before the addition of promoter solution to 5.9 percent by volume after the addition of the first amount of solution (0.32 parts by weight per million pt) and to 4, 1 volume percent after adding the second amount of solution (0.13 parts by weight per million pl). The residual carbon on the regenerated catalyst decreased from 0.30 percent by weight to 0.16 percent by weight after the addition of the first amount of solution by then to 0.06 percent by weight after the addition of the second amount of solution, during the temperature ii of the dense phase of the regeneration zone of 655 ° ^C 681 ° C and then to 71 ° C after the specified amounts of solution had been added. And the regeneration zone temperatures also rose, but not as much as the temperature of the dense phase.

Example 3

This example also illustrates the application of the process of the invention in the same large-scale plant used in Example 2 and further demonstrates the advantages achieved thereby. Before the addition of the two promoter solutions was carried out as in Example 2, a fairly complete investigation was carried out, hereinafter referred to as test 1, for the purpose of comparison with subsequent investigations after adding vuti rromoioriösurig to the regeneration zone during the day after the addition of the first two promoter solutions two further promoter solutions, the promoter corresponding to about 0.13 and 0.32 parts by weight-per-million, based on the circulating catalyst inventory and calculated as metallic Pt, were added in the manner described in Example 2. This time, however, the air supply to the regeneration zone has been increased to ensure that sufficient oxygen is present for essentially complete conversion of CO to CO ₂ . During stationary operation, when the CO was essentially completely burned within the regeneration zone in the presence of the mixture of CO conversion promoter and regenerated catalyst, test 2 then took place. At the time of test 2, the total amount of the in the regeneration *. ^ «Introduced dilute chloroplatinic acid of the CO-oxidation promoter in an amount corresponding to about 0. <parts by weight-per-million, based on the circulating catalyst inventory and calculated as metallic! Platinum. Test 2 was run at virtually the same feed line and practically the same pressures in the regeneration zone and hydrocarbon reaction zone as Test 1. No action was taken to achieve the same level of conversion as Test 1 prior to the start of Test 2 directed any efforts to optimize the flow rate of the air required to achieve essentially complete CO conversion. Relevant results of Test 1 and Test 2 are summarized in Table V.

Table V

Comparative investigations / ur catalytic fluidized bed cracking before and after addition of CO conversion promoter

Tesi
I. 2 before after Processing conditions Hydrocarbon reaction zone Temperature, C 510 505 United charge, lernp., 'C 328 313 Regeneration zone Dense phase temperature, ⁰ C 656 696 Dilute phase temperature, "C 661 699 Exhaust gas temperature, ⁰ C 667 710 Carbon on the regenerated catalyst, 0.28 0.11 uew.- ° / o Exhaust gas analysis, vol .-% CO ₂ 10.5 14.1 CO 9.6 <0, l O ₂ 0.0 3.5 COyCO ratio 1.09 > 140 Product yields C2 and lighter components, wt% 2.7 2.4 Propylene,% by volume 8.5 8.2 Propane, Vo 1 .-% 2.5 2.5 Isobutane, vol .-% 6.1 5.5 n-butane, vol .-% 1.7 1.6 Butenes, vol .-% 9.1 9.2 C ₅ + petrol,% by volume 57.6 57.4 Light circulation oil, vol .-% 20.1 21.2 Sludge oil, vol .-% 3.1 3.8 Coke, wt% 5.4 4.3 Conversion,% by volume 79.7 78.0

A comparison of the test results shows a reduction in the CO concentration of the exhaust gas from 9.6 percent by volume to <0.1 percent by volume, a reduction in residual carbon on the regenerated catalyst from 0.28 weight percent to 0.11 weight percent, allowing better catalyst regeneration and a general increase in regeneration zone temperatures of about 38 to 44 ° C using the method of the invention. Even so, the temperatures of the hydrocarbon reaction zone are not quite the same, the recovery of part of the heat of CO combustion within the Regeneration zone in test 2 shows a significant reduction in the temperature of the combined batch enables. Although the conversion for residue 2 was about 1.7% lower than for test 1. A comparison of the yields shows that Test 2 is selective cracking to more valuable products than in Test 1. The coke yield in Test 2 was 4.3 weight percent versus 5.4 Weight percent in Test 1, and despite the 1.7% lower conversion in Test 2 than that In Test 1, the gasoline yield in Test 2 was approximately the same as that in Test 2 at 57.4 volume percent Test 1 at 57.6 percent by volume. In the event that the same transformation is brought about, then at Using the method of the invention, a significantly higher gasoline yield is achieved.

Long-term operations with the same large-scale plant showed that one essentially full conversion of CO can be sustained when going into the regeneration zone brings in daily amounts of promoter solution on average, the promoter corresponding to about 0.12 parts by weight-per-million of the circulating catalyst inventory, based on metallic platinum.

Platinum analyzes of catalyst samples from this large-scale plant showed that a considerable Part of the promoter remains on the cracking catalyst. For example, at one point it was too a total amount of chloroplatinic acid solution with a total content of promoter corresponding to 75 g Platinum had been introduced into this large-scale facility, a sample of the equilibrium The catalyst located in the system is withdrawn and analyzed for its platinum content. The one from this Sample determined value was 1.0 parts-per-million by weight Platinum. When the entire 75 g of platinum that had been introduced into the plant was evenly distributed over the 54,500 kg of catalyst inventory were distributed, this would result in a concentration of 1.4 parts by weight per million pt on the equilibrium catalyst.

Example 4

This example illustrates the issue of chemical instability of the promoter solution. in the

individually it shows investigations into the chemical instability of a solution of chloroplatinic acid in one Mixture of water and a common freezing point depressant for water, namely ethylene glycol. Chloroplatinic acid with a content of 25.46 percent by weight Pt was in a mixture of the same Parts by weight of technical grade ethylene glycol and water, on the one hand distilled water and on the other other tap water, dissolved to make two solutions each containing 0.045 weight percent Pt. These two solutions were tested for solubility properties at -29 ° C and for their thermal stability tested at 22 °, 43 ° and 63 ° C. The data in Table VI below show that the solutions at -29 ° C flowable solutions remained, but they did not possessed the desired chemical stability for 30 days at 63 ° C; a black precipitate formed

II) in about 11 days at 22 ° C and in only 0.7 days at 63 ° C. The black precipitate was separated off by centrifugation, washed with water and analyzed for its platinum content. The elemental Pt content of the black precipitate was 94% and chemical electron spectroscopic analysis indicated the presence of mainly metallic Pt (Pt ") with about 5% PtO. The platinum recovery from the precipitate, flasks and clear solution gave a value of 100.3% of the amount originally used. These results show that the black precipitate consists essentially of metallic platinum and that the Pt ^M present in the chloroplatinic acid has evidently been reduced to Pt "and the ethylene glycol has been oxidized. Ethylene glycol oxidation products were not identified.

Table Vl

Stability of chlomlatinic acid in a mixture of Äthvlenelvko! and water

sample

Type of water

Days to the Dueling of Precipitation
-29 "C 22 ° C 43 ° C

63 ° C

distilled
management

soluble soluble

4th 0.7

0.7 0.7

example

This example shows studies on the freezing point and chemical stability at temperatures jo of -36 ° C, 22 ° C and 63 ° C five ten solutions of chloroplatinic acid with a concentration accordingly 0.045 weight percent Pt in various undiluted primary, secondary or tertiary alcohols of Reagent grade or mixtures thereof. A temperature of -36 ° C was chosen to be the coldest Take into account temperatures that could occur at the location of a system; the temperature of 22 ° C corresponds to average ambient conditions; the temperature «on 63 ° C was chosen to mean or r> to record any storage conditions that may arise (in and outside of rooms or containers). The time in days until a black precipitate appears, most likely to Mainly made of metallic platinum, for each -n Temperature detected. The results are shown in Table VII below.

The chemical stability of chloroplatinic acid is best with saturated aliphatic primary alcohols, except for methyl alcohol, and inferior to the saturated aliphatic secondary and tertiary alcohols. In addition to unsuitability due to poor chemical stability, the Solution of chloroplatinic acid in 2-methyl-2-pronanol solid at -36 ° C. A classification of the chloroplatinic acid solutions in various solvents in the order of decreasing chemical stability 63 ° C results in: 2-ethyl-1-hexanol (more than 60 days), 1-propanol (more than 58 days), 1-butanol (50 days), ethanol and 1-hexanol (42 to 44 days), 2-methyl-2-propanol (13 days), 2-propanol and 2-butanol (1-2 days), methanol (0.25 days).

Table VII

Resistance of chloroplatinic acid ⁵ ) in different solvents at different temperatures

solution

solvent
Art

Melting point,

Boiling point, -O)

Flash point). O) Days to precipitation
-36 ° C 22'C 63 ° C

1 Methanol -97 65 12th n. b «) 14th 0.25 2 Ethanol -112 78 12th liquid 44 3 1-propanol -127 98 16-29 liquid > ο I > 58 4th 2-propanol -85 83 12-16 n.b. 7th 1 5 1-butanol -89 117 37 ') liquid > 63 50 6th 2-butanol -89 100 24 n.b. 56 2 7th 2-methyl-2-propanol 25th 83 11th Solid 22nd 13th 8th 1-hexanol -51 157 74 liquid > 56 42 9 2-ethyl-1-hexanol -70 184 85 > 60 > 60 > 60 10 Ethanol + 1-butanol (1: 1) - n.b. > 48 > 48

) Literature values for the melting point, the boiling point and the flash point. Closed cup flash point, Cleveland.
Penske - Martens determinations with closed beaker, na = not determined.
Chloroplatinic acid concentration in each solution corresponds to 0.045 percent by weight Pt.

Example 6

This example describes! Investigations in the regeneration zone of a semi-technical test facility, those used to determine the effectiveness of a solution containing chloroplatinic acid in isobutanol for the reduction in the concentration of CO in the exhaust gas was carried out. The investigations were carried out using the test device explained in Example 1. As in Example I, there were precautions taken to heat the device to a constant temperature, and by means of a chromatographic Device, samples of the exhaust gas were continuously taken from the vessel and checked for CO, CO2 and Oj analyzed. A chromatographic l.inie.vug for CO, CO2 and O2 was recorded, so dali Instantaneous analyzes to characterize the combustion of CO during the test were available. A specific CO2 / CO ratio, hereinafter referred to as the C02 / C0 minimum ratio, was established is, from the chromaiographic lines for everyone The test is determined by first determining the maximum CO concentration for the test (which is usually within 2 up to 3 minutes after initiation of the combustion), and the CO2 concentration at the moment the maximum CO concentration is determined and then the CO2 / CO ratio for the concentrations determined in this way was calculated. This ratio has been referred to as the CO2 / CO minimum ratio, as many Such regeneration tests have been observed that in the event of the current CO2 / CO ratios versus elapsed time for each test gives a curve that goes through a minimum and the CO2 / CO ratio at that minimum has a value as calculated by the method explained above. It has been shown that this OZ ^ / CO minimum ratio best the effect and Performance of any solution containing a CO promoter to catalyze CO combustion indicates.

The tests were performed on 500 g samples of an equilibrated zeolite Fluidized bed cracking catalyst that has previously been "used up" by a Gas oil feed to a pilot scale hydrocarbon reaction zone which is used at Standard conditions with a predetermined sequence of work measures through which Equilibrium catalyst sample was passed. Each sample of the spent catalyst contained approximately 0.9 Weight percent coke.

The Tesi I did not use a promoter-containing solution admitted. This. · Test was carried out to a

ι Basis for a comparison with a subsequent one Test using a promoter-containing solution. A 500g sample of the vel was needed Catalyst was poured into the vessel and fluidized with nitrogen entering at the bottom of the vessel,

Was heated 1 "while the device to a temperature of 593 ⁰ C. At a fixed point in time, the nitrogen was replaced by air and this initiated the oxidation of coke. The exhaust gas from the vessel was based on the chromatographic device

ι ι CO2, CO and O2 analyzed and the CO ₂ / CO mipima! ratio was calculated from the lines for CO2 and CO. To determine a measure for the reproducibility of the results obtained according to this test method, the test was repeated a total of four times with separate samples of the used catalog. The CO2 / CO minimum ratios were in the range from 2.5 to 3.3, as can be seen from Table VIII below.

Test 2 was carried out in the same manner as Test 1

Performed 2ι , with the exception that immediately before switching the fluidizing nitrogen to air, a 25 g sample of a solution of chloroplatinic acid in 1-butanol was injected into the regeneration zone. The concentration of chloroplatinic acid in the sample

in corresponded to 0.008 percent by weight of Pt and the amount of platinum in the sample was 2 mg Pt, i.e. H. 4 parts per million by weight based on the 500 g catalyst sample. It the result was a minimum CCVCO ratio of 52.1. To get a measure of the speed with which the

r, particle mixture of promoter and regenerated catalyst particles to reduce its effectiveness If the CO concentration in the exhaust gas was lost, the mixture was operated in further cycles. in the individually, the mixture in the hydrocarbon reaction zone was used to complete a further cycle ve η semi-technical experimental scale in the manner described above in the "Used up" and then the regeneration zone test was repeated, but without any addition any further amounts of pro notor solution. At the end of the seventh cycle that was COj / CO minimum ratio for the particle mixture 41.5, indicating that the mixture had largely retained its CO combustion activity. Results of Tests 1 and 2 are shown in Table VIII.

Table VIII

Regeneration zone investigations in a semi-technical test facility with and without Use of a promoter solution

test

no use of promoter solution

COi / CO minimum ratios

Cycle

12 3 4

3.3

2.5 -

3.1

3.0 -

32

COyCO-M inimal ratios

Cycle

12 3 4

Test 2

25 g solution of chloroplatinic acid 52.1 in 1-butano! with a Content of 0.008 wt.% Pt

41.5

Solutions of chloroplatinic acid in other preferred solvents behave similarly to the solution of chloroplatinic acid in 1-butanol used in this example.

Claims (16)

Patent claims: 1. Process for the regeneration of coke-contaminated catalysts with simultaneous carefully controlled combustion of carbon monoxide, characterized in that man (a) introduces catalyst contaminated with coke into a regeneration zone, (b) a carbon monoxide oxidation promoter in to the regeneration zone in one regardless of the catalyst contaminated with coke Brings amount to promote the combustion of carbon monoxide to carbon dioxide, (c) oxygen-containing regeneration gas in the Re- π generation zone in an amount to burn coke off the contaminated catalyst and to provide enough excess oxygen to bring about the desired level of carbon monoxide consumption. initiates breiming, (d) a first part of the oxygen-containing regeneration gas with the coke-contaminated catalyst in the regeneration zone under oxidation conditions for the removal of coke 2> from the coke-contaminated catalyst and the generation of an exhaust gas containing carbon monoxide and sufficient to bring about a combustion of carbon monoxide to carbon dioxide in the presence of the m oxidation promoter, converts and (e) the exhaust gas and a second part of the oxygen-containing regeneration gas at the same time the carbon monoxide oxidation promoter in the regeneration zone in the presence of π regenerated catalyst at the oxidation conditions, and thereby (1) a controlled amount of exothermic Makes reaction heat available for the operation of the regeneration zone and (2) the amount -to of carbon monoxide in the exhaust gas. 2. The method according to claim 1, characterized in that the carbon monoxide oxidation promoter is introduced in step (b) in the form of a solution in a solvent 4 ^r > 3. The method according to claim 2, characterized in that there is a solvent, the water or comprises or consists of a liquid hydrocarbon 4. The method according to claim 2, characterized in that one solvent which comprises or consists of an alcohol from the group of saturated aliphatic primary alcohols with 2 to 8 carbon atoms per molecule and freezing points of 0 ⁰ C or below, is used , 5. The method according to claim 4, characterized in that the primary alcohol is 1-butanol or 2-ethyl-1-hexanol is used 6. The method according to any one of claims 1-S _1, characterized in that the carbon monoxide> oxydoxydationspromotor is introduced into the regeneration zone introduces in such an amount that exhaust gas that Contains carbon monoxide in an amount equal to or less than a predetermined amount. 7. The method according to any one of claims 1-5, h3 characterized in that the carbon monoxide oxidation promoter is introduced into the regeneration zone in step (b) in such an amount that a sufficient amount of exothermic heat of reaction is released to bring the mean combustion temperature in the regeneration zone to a Increase height, at which a regenerated catalyst, the remaining carbon in a Quantity less than or equal to a predetermined value is generated. 8. The method according to any one of claims 1-5, characterized in that the carbon monoxide oxidation promoter is in the regeneration zone in step (b) in such an amount that a sufficient amount of exothermic heat of reaction to raise the temperature of the regenerated To increase the catalyst to a predetermined level, is made free. 9. The method according to any one of claims 1-5, characterized in that the amount of in of stage (b) introduced into the regeneration zone carbon monoxide oxidation promoter ί jf a Sets a value which is sufficient to ensure that im essentially all of the carbon monoxide released from exothermic combustion Heat is released in the presence of regenerated catalyst, and thereby a Control of the temperature of the exhaust gas below a predetermined level allows 10. The method according to any one of claims 1-5, characterized in that the amount of carbon monoxide oxidation promoter introduced into the regeneration zone in step (b) in conjunction with an amount of diluent gas supplied to the regeneration zone is adjusted in order to control the temperature of the exhaust gas flowing off allow below a predetermined level. 11. The method according to any one of claims 1 - 10, characterized in that a carbon monoxide oxidation promoter from the group of Precious metals and their compounds are used 12. The method according to claim 11, characterized in that one uses a carbon monoxide oxidation promoter from the group of platinum, palladium and their compounds 13. The method according to any one of claims 1 - 12, characterized in that the oxidation promoter of the regeneration zone in step (b) in an amount corresponding to 0.1 to 15 parts by weight per million of the circulating catalyst inventory, based on elemental metal 14. The method according to any one of claims 1-13, characterized in that the oxygen-containing regeneration gas in an amount corresponding to 10 to 17 kg of air per kg of coke entering the regeneration zone, per unit of time 15. The method according to any one of claims 1-14, characterized in that one in the regeneration zone oxidation conditions with a temperature of 590 to 79O ° C and a pressure of Maintains atmospheric pressure up to 43 atm 16. The method according to any one of claims 1-15, characterized in that the regeneration zone is the Köhlenmonoxydoxydatiorispromotor in an average daily amount corresponding to 0.005 to 10 parts by weight per million of the circulating catalyst inventory, based on elemental Metal, feeds.