DE2703521A1 - METHOD OF REGENERATING COCK-CONTAMINATED CATALYSTS WITH CAREFULLY CONTROLLED COMBUSTION OF CARBON MONOXYDE - Google Patents

Description

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

The invention relates to hydrocarbon processing and especially catalytic cracking processes. In particular, it relates to a method for regenerating cracking catalysts contaminated with coke with simultaneous carefully controlled combustion of carbon monoxide to carbon dioxide in the regeneration zone of a catalytic cracking process.

Regeneration methods in which a catalyst contaminated with coke regenerates in a regeneration zone represent a broad area of chemical and hydrocarbon processing technology . Regeneration methods for the regeneration of coke-contaminated, fluidizable cracking catalysts in the regeneration

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ration zone of a fluid catalytic cracking process (hereinafter mostly referred to as fluidized bed cracking for the sake of simplicity). Until a few years ago the prior art has dealt primarily with removing the greatest possible amount of coke from the consumed Remove catalysts while doing so to prevent excessively high temperatures as they result from the conversion from carbon monoxide to carbon dioxide within certain areas of the regeneration zone, especially in the Area where the catalyst is in a dilute phase, so little catalyst is present to absorb the heat of reaction and consequently heat damage to cyclones or other separating devices can occur. One essentially complete carbon monoxide conversion 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 oxygen to maintain the oxidation of carbon monoxide to carbon dioxide can of course be post-combustion do not enter, no matter what the temperatures in the regeneration zone are. Furthermore, the temperatures in the ! (o-generation zone generally to less than about 675 ° C limited by appropriate choice of the operating conditions in the hydrocarbon reaction zone or the fresh feed streams or the recycle streams or combinations of these Measures to thereby reduce the amount of coke on the spent catalyst and thus the amount of in the regeneration zone to limit spent combustible material. The exhaust gas produced, which contained several percent by volume of carbon monoxide, was either blown directly into the atmosphere or in a CO boiler downstream of the regeneration zone as Fuel used.

The usual method of starting a fluidized catalytic cracking process as known to those skilled in the art on the

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The art of fluid catalytic cracking has been to initially manually control the flow of fresh regeneration gas to the regeneration zone in an amount insufficient to sustain essentially complete carbon monoxide conversion while keeping regeneration zone temperatures up to a maximum of about 675 ° C to restrict. After the fluidized catalytic cracking process had reached a usable steady state and adjusted, the flow rate of the fresh regeneration gas was then regulated, normally by instrument control in direct response to 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 automatically maintain this proper flow rate of fresh regeneration gas and preclude substantially complete conversion of CO to CO- anywhere within the regeneration zone. When the temperature differential increased beyond a predetermined temperature differential, indicating that greater conversion of CO was taking place in the dilute phase, the amount of fresh regeneration gas was reduced to prevent substantially complete conversion of CO to CO ₂ . This control method is described, for example, in US Pat. Nos. 3,161,583 and 3,206,393. This method leads to a small amount of oxygen in the exhaust gas, generally in the range from 0.1 to 1 percent by volume 0.1, but it makes an essentially complete conversion of CO to CO within the regeneration zone impossible.

Until the introduction of zeolite-containing catalysts, there was only a relatively low economic incentive for essentially complete conversion of CO to CO-within the regeneration zone. The use of zeolite Fluidized bed cracking catalysts, which are thermally stable and have a lower tendency to form coke, and the

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Use of higher temperatures in the hydrocarbon conversion zone however, often require additional heat to be introduced into the catalytic fluidized bed cracking process or made desirable. Typically, additional heat was added by burning an externally Fuel, e.g. from auxiliary fuel oil, in the regeneration zone or by applying or increasing the amount of feed preheat fed into external feed preheaters. Normally, on the one hand, there was heat in the introduced catalytic fluidized bed processes and on the other hand then later removed therefrom, namely by two external equipment or plant components, a feed preheater and a CO boiler, both of which represent considerable investment and entail operating costs. Have catalyst regeneration methods described in the more recent prior art the advantages of essentially complete conversion of CO to CO and recovery of at least a portion of the Heat of combustion of carbon monoxide, both within the regeneration zone, recognized. As examples of such regeneration processes U.S. Patents 3,844,973 and 3,909 may be mentioned. The advantages of such operations are now accepted; such regeneration processes allow the feed preheat to be reduced or eliminated, the elimination of air pollution from carbon monoxide without the need to arrange external CO boilers and, when operated in conjunction with hydrocarbon reaction zones modern education, improved yields of more valuable products.

Regeneration processes using CO conversion promoters or catalysts have already been given been; such are conventional processes for regenerating fluidizable, coke-contaminated cracking catalysts such promoters or catalysts have been used. For example, the one disclosed in U.S. Patent 2,436,927

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(1948), the fluidized bed catalytic cracking process described uses a physical mixture of separate particles of a cracking catalyst and separate particles of a supported CO oxidation catalyst in a dense phase area of a regeneration zone in order to promote a CO conversion in the dense phase and thereby an "afterburning" in the dilute phase area to prevent the regeneration zone. In the process described in US Pat. No. 3,364,136 (1968), a mixture of a cracking catalyst and a shape-selective crystalline aluminosilicate containing an oxidation catalyst within its internal pore structure is used to control the CO ₂ / CO ratio in the regeneration zone without affecting it the reaction taking place in the hydrocarbon reaction zone is used. The process described in US Pat. No. 3,808,121 uses two separate catalysts of different particle size and composition, namely a cracking catalyst and a CO oxidation catalyst, preferably supported in a matrix material such as alumina spheres and monoliths. Furthermore, the carrier-containing CO oxidation catalyst is or within the Regenerati. s ζ one and it does not flow out of this zone to the hydrocarbon reaction zone like the cracking catalyst does. Coke and carbon monoxide are subjected to oxidation in the regeneration zone in order to keep the CO content in the exhaust gas as low as possible.

Previous regeneration processes thus have CO oxidation promoters used in either of the following two ways; (1) on separate particles of a matrix or a Carrier, the particles to be admixed with the fluidized cracking catalyst, and (2) as a part or component of the fluidized cracking catalyst itself. Mixtures of cracking catalyst vincl carrier-containing CO oxidation promoters tend to be irregular, which leads to a CO concentration in the exhaust gas above permissible emission restrictions.

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The use of a cracking catalyst as a component any predetermined concentration of a CO oxidation promoter contains, makes it difficult to find the optimal concentration in any given regeneration zone to bring about oxidation promoters suitable for the operating characteristics of this particular regeneration zone or to achieve a particular change of a dependent procedural variable are required.

By the method of the invention, a CO oxidation promoter of the regeneration zone becomes independent of the Cracking catalyst fed, oxidizing coke from the spent catalyst to produce regenerated catalyst and essentially simultaneously carbon monoxide in the presence of the promoter and the regenerated catalyst converted to carbon dioxide within the regeneration zone. In this way it can act as a carbon monoxide oxidation promoter easily and precisely, especially when it is in a liquid, into the regeneration zone in quantities for control the CO concentration in the exhaust gas, to control a temperature within the regeneration zone or to control the amount be introduced of residual carbon on the regenerated catalyst. The introduction of a CO oxidation promoter according to the method of the invention is accordingly simpler, better and more economical than either using separate ones Particles of a supported CO oxidation promoter along with a cracking catalyst or the use of a Cracking catalyst to which a CO conversion promoter has been added during the catalyst manufacturing process. About that In addition, the method of the invention provides the operating personnel with an operating condition as a process variable, which hitherto was essentially a fixed operating condition. Accordingly, the drive implementation is when using the Method of the invention of increased operational flexibility and

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-adaptability. The process of the invention is applicable to any existing or newly installed fluidized bed cracking process applicable.

The invention is therefore based on the object of an improved method for regenerating a catalyst contaminated with coke with simultaneous carefully controlled combustion of carbon monoxide in a regeneration zone and an operating procedure which makes a controlled amount of exothermic heat of reaction available for the operation of the regeneration zone and the amount of carbon monoxide reduced in the exhaust gas to create that does not have the above 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, to indicate a mode of operation for utilizing the On-site combustion of CO to CO ₂ for controlling the operation of the regeneration zone. In connection therewith, 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 under coke oxidation conditions to produce a regenerated catalyst and an exhaust gas containing CO and CO 2} , the indication (1) of a mode of operation for controlling the CO concentration in the exhaust gas within a predetermined CO concentration range, (2) a mode of operation for controlling a regeneration zone temperature within a predetermined temperature range and (3) a mode of operation for controlling the concentration of residual carbon on the regenerated catalyst within a pre-

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certain residual carbon concentration range.

For this purpose, the invention relates to a process for regenerating catalysts contaminated with coke with simultaneous carefully controlled combustion of carbon monoxide, which is characterized in that one

(a) introduces catalyst contaminated with coke into a regeneration zone,

(b) a carbon monoxide oxidation promoter in the regeneration zone regardless of the catalyst contaminated with coke, in an amount that promotes combustion is chosen from carbon monoxide to carbon dioxide, brings in,

(c) oxygen-containing regeneration gas into the regeneration zone in an amount sufficient to burn coke off the coke-contaminated catalyst and display excess 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 at oxidation conditions that remove coke from the coke-contaminated catalyst and are selected to produce an exhaust gas containing carbon monoxide and those to induce combustion from carbon monoxide to carbon dioxide in the presence of the oxidation promoter suffice, converts and

(e) the exhaust gas and a second portion of the oxygen at the same time containing regeneration gas with the carbon monoxide oxidation promoter in the regeneration zone in the presence of regenerated catalyst under the oxidation conditions brings into contact, and thereby (1) a controlled amount of exothermic heat of reaction for operation the regeneration zone and (2) the amount

of carbon monoxide in the exhaust gas.

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In connection with this, according to another embodiment of the invention, a method for catalytic Cracking a hydrocarbon feed stream using coke contaminated cracking catalyst and oxygenated Regeneration gas are passed into a regeneration zone maintained at coke oxidation conditions, in which Coke is oxidized to produce a regenerated catalyst and an exhaust gas containing carbon monoxide and carbon dioxide is a way of working to utilize the on-site combustion of carbon monoxide to carbon dioxide for the control of the operation of the regeneration zone is provided, which is characterized in that (a) the regeneration zone is independent of the catalyst contaminated with coke a carbon monoxide oxidation promoter in an amount sufficient to initiate and maintain carbon monoxide combustion in the regeneration zone in the presence of the regenerated Catalyst is selected, feeds and (b) then the amount of the oxygen-containing passed to the regeneration zone Adjusts regeneration gas to a value that is stoichiometric to burn off the coke from the catalyst and to Conversion of at least part of the carbon monoxide into carbon dioxide is sufficient, and thereby (T) a controlled amount of 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, amounts of a carbon monoxide conversion promoter to be added, methods of incorporation a Konlenmonoxide conversion promoter in the regeneration zone, as well as the operating conditions; further information on this can be found in the further explanation below of the invention.

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First, for the sake of clarity and a better understanding of the method of the invention, several will be used herein Expressions defined.

The term "hydrocarbon reaction zone" denotes the part of a catalytic fluidized bed cracking plant, in which a regenerated catalyst hydrocarbon feed stream is produced under cracking conditions a mixture of fluidized bed catalytic cracked product components, coke contaminated (or spent) catalyst and any unreacted charge is brought into contact. Typical fluid catalytic cracked product components, as arranged after separation in downstream of the hydrocarbon reaction zone Facilities obtained are C fuel gas, C and C fractions, a gasoline fraction, light cycle oil and clarified mud oil. After the product components have been separated off, at least part of the consumed catalyst is added the regeneration zone. The terms "catalyst contaminated with coke" or "spent catalyst" are interchangeably and denote catalyst that is reduced by a hydrocarbon conversion zone Activity has been withdrawn as a result of coke deposits. Used catalyst flowing into the regeneration zone may contain a few tenths up to about 5 weight percent coke; usually contains the spent catalyst about 0.5 to about 1.5 weight percent coke in fluid catalytic coke operations.

The designation "regeneration zone" identifies the Part of the catalytic fluidized bed cracking plant in which an oxygen-containing regeneration gas and at least one part of the spent catalyst and in which at least a portion of the coke from the spent catalyst by oxidation with the generation of regenerated catalyst

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Sator and an exhaust gas containing CO and CO is removed. "Regenerated catalyst" is a catalyst from which at least a portion of the coke has been removed by oxidation. Regenerated catalyst as produced using the process of the invention generally contains less than about 0.3 percent by weight coke, and more preferably about 0.01 to about 0.15 percent by weight coke. As used herein, the term "regeneration gas" is to be understood in the general sense as any gas which is to be brought into contact with the catalyst or which has been in contact with catalyst in the regeneration zone. The term "oxygen-containing regeneration gas" denotes a regeneration gas which contains free or unbound oxygen, for example air or air enriched with oxygen or air containing an oxygen deficiency, and which flows into the regeneration zone in order to burn off coke from the spent catalyst and convert it of CO. The term "exhaust gas" denotes regeneration gas which has been in contact with catalyst within the regeneration zone and which flows out of the regeneration zone. The exhaust gas contains nitrogen, free oxygen, carbon monoxide, carbon dioxide and water. Since CO and CO ₂ concentrations are used to carry out routine calculations for the catalytic fluidized bed cracking process and since the CO represents a potential fuel that can be burned within the regeneration zone or in an outer CO boiler or possibly in both ways, and there Furthermore, there are mostly restrictions with regard to air pollution due to the emission of CO, the exhaust gas is normally characterized by the concentrations of CO and CO ₂ or by the molar ratio of CO ₂ / CO. Depending on the operating conditions used in the regeneration zone, in particular the amount of the oxygen-containing regeneration gas passed into the regeneration zone, the concentrations of CO in this exhaust gas can

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can vary over a wide range from a few hundred parts-per-million or even less to up to about 15 percent by volume or more, and the concentration of CO- can range from about 5 percent by volume to about 20 percent by volume. If the regeneration zone is operated under conditions to prevent controlled oxidation of carbon monoxide within the regeneration zone, the concentrations of CO and CO- are approximately the same, both within the range of about 7 to about 15 percent by volume, and the C0 ₂ / CO- The molar ratio is then in the range from about 0.8 to about 1.5. When the regeneration zone is operated under conditions to achieve partially complete oxidation of CO, the concentration of CO will be lower than that of CO and, in particular, the CO / CO molar ratio will normally be from 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 CO concentration is typically less than about 1000 parts-per-million, preferably less than 500 parts-per-million, and the CO ₂ / CO mole ratio is greater than about 100.

The terms "dense phase" and "dilute phase" are common terms in the fluid catalytic cracking art to generally identify catalyst densities in various 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 2; the term "dilute phase" denotes 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 or more and

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the density of the thinned-phase area is far below 80 kg / m and in the range from about 1.6 to about 80 kg / m. Catalyst densities in regeneration zones are usually determined by Measurement of pressure or column differences (head differences) along pressure sensors that are installed in the vessels and in known ones Are spaced from each other.

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 line 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 (4350 BTü / lb), post-combustion can accordingly lead to severe damage to the catalyst separation devices arranged in the dilute phase. In general, afterburning is manifested by a rapid increase in temperature and occurs during periods of unsteady operating conditions or "fluctuations" or "disturbances" in the process sequence. Accordingly, it is 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" are intended of CO "the deliberate, controlled and sustained oxidation of CO in the presence of sufficient catalyst for absorption at least part of the heat of reaction, so that at least part of the heat of reaction is obtained and one Damage to equipment in the regeneration zone is excluded. Depending on the operating conditions used the controlled oxidation of CO may be partially complete or substantially complete. "Partially completed "should mean that the CO concentration in the

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Exhaust gas has been reduced so far that the C0 ₂ / CO molar ratio of the gas is in the range from 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 eLwa 10Ö. Typically, the substantially complete CO conversion results in 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 ^11” 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 by 2 to 5 times or even much more, thus a faster rate of CO conversion can be achieved under conversion conditions in the presence of a CO conversion promoter than can be achieved under the same conversion conditions without the promoter. Conversely, the same CO conversion rate can be achieved under less severe conversion conditions, for example with regard to temperature, than are necessary without the CO conversion promoter.

The amount of CO conversion promoter introduced into a regeneration zone can be expressed expressed as the amount required to bring about a desired change in a variable, or it can are in terms of the circulating catalyst inventory or the catalyst circulation rate or the replenishment rate for fresh cracking catalyst or, as the case may be, in terms of a unit quantity of the feed. In the present Documents, the amount of promoter is usually expressed as the amount required to achieve a desired

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to bring about a change in a variable such as the temperature, the CO concentration or the residual carbon content, or it is expressed as parts-per-million by weight of the circulating catalyst inventory. The term "circulating catalyst inventory" indicates the amount of the cracking catalyst in the fluidized catalytic cracking process passing from the regeneration zone to the hydrocarbon reaction zone and can be circulated back again. It differs from the total cracking catalyst inventory, as there is usually a certain proportion of the total catalyst inventory that is not available for circulation, e.g. the proportion of the total stock that is typically located in the cone section of the regeneration zone below the pipe grid.

Taking these definitions into account, today's typical operating modes of catalytic fluidized bed cracking are briefly mentioned considered with particular attention to the operation of the regeneration zone. Modern operational implementation of the fluid catalytic cracking has been achieved through the widespread use of crystalline aluminosilicate cracking catalysts and through the use of short hydrocarbon-catalyst contact times, for example by riser cracking, a considerable reduction in the coke yield is achieved. Although this led to higher yields of more valuable gaseous and liquid products, on the other hand it was but the amount of solid combustible substance required for combustion in the regeneration zone is reduced the global balance sheet requirements of the process stands. More recent prior art processes have recognized that by the combustion of coke produced by the oxidation CO within the regeneration zone and recovery of at least part of the exothermic heat of reaction is sufficient Amount of heat for the heat balance requirements, which are determined by a wide range of operating conditions and applications

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materials are brought about is available. Such CO combustion also has further reductions in coke yields and increases in the yields of gaseous and liquid products, as well as a decrease or elimination allows for feed preheating while eliminating the need for an external CO boiler Eliminated air pollution problems from CO release into the atmosphere. Typical modern regeneration zones show a single cylindrical vessel containing a dilute phase in the upper portion of the vessel containing cyclone separators and contains a dense phase in the lower portion of the vessel. Used catalyst occurs on the side or bottom of the vessel and fresh regeneration gas is fed in and through at the bottom of the vessel a pipe grid or an array of perforated plates distributed within the dense phase. Coke is under production oxidized by regenerated catalyst as well as CO and CO2 containing exhaust gas and CO can in the presence of a sufficient Amount of catalyst to obtain at least part of the heat of combustion are further oxidized. Hauled catalytic converter exhaust gas containing it 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 from the regeneration zone forward. Limiting or limiting considerations for the operation of the regeneration zone include the performance of the air blower, limits of the Resilience of the cyclone separator (s), restrictions with regard to the emission of CO and entrained particles by the exhaust gas as well as restrictions on the container temperatures. During the operation of the regeneration zone, the Operating personnel primarily the extent of the catalyst regeneration, the regeneration zone temperatures and the Concentration of CO and debris in the exhaust gas

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to be observed and to be monitored closely. It is typical Refinery practice to periodically take samples of the regenerated catalyst and use known methods on their Analyze residual carbon content 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 for the regeneration vessel existing metallurgical restrictions are not exceeded. Furthermore, it is typical Practice to periodically or continuously take samples of the exhaust gas and check its concentrations of CO, Ο ~, CO and to analyze particulate components. The gas analyzes can be carried out by any known method e.g. Orsat analysis, gas chromatographic methods and mass spectroscopic methods. Particulate material can be determined by opacity measurements or other known analyzes testicles are determined. Gas analysis results can be used for calculation, using the carbon-nitrogen-oxygen balance, such data as coke composition, coke burn rate, need for oxygen-containing regeneration gas, heat of combustion of the Coke and amount of CO in an outer CO boiler or in the regeneration zone of the fluidized catalytic cracking process or, if necessary, can be incinerated in both. Before the exhaust gas directly into the atmosphere can be blown off, the operator must also check the concentrations of CO and particulate matter in the exhaust gas to determine whether the exhaust gas meets local air pollution restrictions with regard to C0 emissions. The concentration of 0, in the exhaust gas is important to ensure that the amount of oxygen-containing regeneration gas is sufficient to generate the desired To maintain the extent of CO combustion, be it a partially completed or essentially complete CO combustion

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tion, on the other hand, is not supplied in such a large excess that an unnecessary load on the fan capacity for the oxygen-containing regeneration gas.

A feature of the process of the invention in all of its embodiments is that a CO oxidation promoter is introduced into the regeneration zone independently of the cracking catalyst. Useful carbon monoxide oxidation promoters include metals from Groups Ib, Hb, Via, VIIa and VIII of the Periodic Table of the Elements and compounds thereof. Chromium, nickel, iron, molybdenum, cobalt, copper, zinc, manganese and vanadium and compounds thereof may be mentioned as representative examples. Preferred CO oxidation promoters are the noble metals and compounds thereof since it has been found that only very small amounts of these promoters are required to achieve the desired results. The term “precious metals” is to be understood in the usual way as the metals gold, silver, mercury, platinum, palladium, iridium, rhodium, ruthenium and osmium. The promoter can be added to the regeneration zone in the form of a solid, for example as powder, chips, pellets or agglomerates, but the promoter is preferably introduced in a liquid for reasons of ease of handling and control. The liquid containing the promoter can be added continuously or intermittently by means of known media flow and control devices. For example, the liquid containing the promoter can be squeezed out of a cylinder or a pressure bottle which is connected by pipe connections to an auxiliary fuel oil nozzle or a probe guided through a pressure discharge nozzle, the inflow being controlled by a valve in the connecting line. The liquid can also be poured into the tank in a quantity / time controlled by a small positive displacement pump

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Nozzle or probe. The CO conversion promoter can be dispersed in the liquid in the form of a colloidal dispersion or suspension or it can be in the liquid be soluble. Particularly preferred oxidation promoters are noble metals or compounds thereof, which are in water or a liquid hydrocarbon are soluble or dispersible. Suitable water soluble metal compounds include Metal halides, preferably chlorides, nitrates, amine halides, oxides, sulfates, phosphates and other water-soluble ones inorganic salts. Examples of suitable water-soluble compounds are chloroplatinic acid, palladium acid, palladium chloride, Called ruthenium tetrachloride, rhodium trichloride, rhodium nitrate and osmium trichloride. Alternatively, a liquid hydrocarbon that is oil-soluble or in oil Contains dispersible CO oxidation promoter, are fed to the regeneration zone. To suitable liquid hydrocarbons include hydrocarbons normally liquid at atmospheric temperatures and pressures, such as e.g. heavy gasoline and light cycle oil. Oil-soluble or UI-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 acetyl acetate, palladium acetate, palladium naphthenate, Triiodiridium (III) -tricarbonyl and (7Γ, cyclopentadienyl) - (ethylene) -rhodium (I) called. The noble metals and their compounds become platinum and palladium and compounds thereof preferred, especially water-soluble compounds as they are usually more accessible than compounds, which are soluble or dispersible in oil. Chloroplatinum acid and palladium acid are particularly preferred water-soluble platinum and palladium compounds.

In order to ensure a wider usability in technical application, however, solutions are often

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CO oxidation promoters with a freezing point of 0 ° C or below are 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 system. Solvents that form solutions with chloroplatinic acid or chloropalladic acid that have freezing points of O ⁰ C (32 ° F) or below are alcohols from the group of saturated aliphatic alcohols with 2 to about 8 carbon atoms per molecule and freezing points of O ⁰ C or below . As examples of such alcohols, together with their freezing points may be mentioned: methanol (-98.7 ⁰ C), ethanol (-112 ⁰ C), 1-propanol (-127 ⁰ C), 2-propanol (-85.8 ⁰ C), 1-butanol (-89.2 ⁰ C), 2-butanol (-89 ⁰ C), 2,3-dimethyl-2-butanol (-14 ⁰ C), 2-methyl-2-butanol ( -14 ⁰ C), 2-methyl-2-butanol (-11.9 ⁰ C), 1-pentanol (-78.5 ⁰ C), 1-hexanol (-51.6 ⁰ C), 2-ethyl- 1-hexanol (-70 ⁰ C), 1-heptanol (-34.6 ⁰ C), 4-heptanol (41.5 ⁰ C) and 1-octanol (-16.4 ⁰ C).

Are particularly suitable, as already stated, solutions of a C0-Oxydationspromotors, the freezing point of about -34 ° C (-30 ⁰ F) or still have among them so that they are still liquid even at the at the site of a plant that may occur coldest temperatures are. Accordingly, particularly preferred solvents are the solvents which, with chloroplatinic acid or chloropalladic acid, give solutions with the desired freezing points of -34 ° C. or below. Suitable solvents here are also alcohols from 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 listed in the above compilation, with the exception of 2,3-dimethyl-2-butanol, 2-methyl-2-butanol and 1-octanol, since these three alcohols do not have freezing points of -34 ° C or below.

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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, so that no chemical change - indicated by the appearance of a further liquid phase or a solid phase - during the storage periods in question entry. To be on the safe side with regard to adverse storage conditions that may arise, such solutions should be chemically stable for a period of 30 days at a temperature of 63 ° C (145 ° F). Some of the aforementioned saturated aliphatic alcohols that give solutions that meet the preferred freezing point specification of -34 ° C did not give solutions that were chemically stable for 30 days at 63 ° C. For example, methanol, 2-propanol, 2-butanol and 2-methyl-2-propanol did not produce any solutions which were chemically stable at 63 ° C. for 30 days. In addition, some common 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 with 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 being particularly preferred. In general it was found that - with the exception of methanol - the chemical stability of the solutions was best when the solvent of a saturated aliphatic primary alcohol component, and was inferior when the solvent has been formed from a saturated aliphatic secondary or tertiary alcohol. Preferably

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are these saturated aliphatic primary alcohols with 2 to about 8 carbon atoms per molecule and freezing points of -34 ° C or below used in a pure, undiluted state with chloroplatinic or chloropalladic acid. Preferred concentrations of chloroplatinic or chloropalladic acid in the solution are corresponding concentrations about 0.01 to about 10 percent by weight Pt or Pd, with concentrations of about 0.01 to 5 percent by weight Pt or Pd are particularly preferred.

To best ensure optimal utilization of the very small amounts of promoter required, In the process of the invention, the addition of the promoter is limited to the regeneration zone. By feeding the Promoters directly into the regeneration zone, where the CO oxidation to be catalyzed takes place, results in a practical immediate response, allowing a controlled amount of exothermic heat of reaction to operate the regeneration zone made available and the concentration of carbon monoxide in the exhaust gas is reduced. The CO conversion promoter can be in the dense phase or the dilute phase of the regeneration zone. Albeit the promoter at several Feed points can be introduced, it has been found that using only a single feed point be able to achieve satisfactory results. The typical regeneration zone vessels have a number of pressure sensors and auxiliary fuel oil nozzles, one or more of which can serve as feed points; accordingly only a very slight modification of the vessel itself is required, before the method of the invention can be used.

In one embodiment, the invention provides a Working method for the regeneration of coke-contaminated catalyst with simultaneous carefully controlled combustion

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tion of carbon monoxide. In this embodiment of the In the process, the catalyst contaminated with coke is introduced into the regeneration zone and the CO oxidation promoter is in the regeneration zone regardless of the coke contaminated Catalyst introduced in an amount tailored to the desired promotion of the combustion of CO to CO ^. The amount of promoter added corresponds to about 0.1 to about 25 parts-per-million by weight of the circulating catalyst inventory, on an elemental metal basis, 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 fed into the Regeneration zone initiated in an amount that has enough excess oxygen to bring about the desired Extent of CO combustion results. In particular, corresponds this amount of oxygen-containing regeneration gas is 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 to be partially completed or substantially complete. It has been found to be important Introduce promoter first into the regeneration zone and then the oxygen-containing regeneration gas, so that a smooth, controlled catalytic conversion of CO initiated from the start and the possibility of post-combustion is suppressed as far as possible. When this amount of oxygen f-containing regeneration gas is first introduced into the regeneration zone and the promoter is then added the risk that an afterburning instead of the desired controlled conversion of CO in the presence initiated by 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 for Removal of coke from the catalyst and generation

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an exhaust gas containing CO and are sufficient to _{bring about a combustion of CO to CO 2} in the presence of the oxidation promoter. The oxidizing 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 (50 psig). Under such conditions, coke oxidation occurs essentially spontaneously.

The exhaust gas and a second part of the oxygen-containing regeneration gas are essentially simultaneously brought into contact with the C0 oxidation promoter under the oxidation conditions specified above, whereby a controlled amount of 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 the oxidation promoter introduced into the regeneration zone can be adjusted according to the extent to which it has been achieved certain desired results can be selected, e.g. a desired concentration of CO in the exhaust gas or a * desired extent of catalyst regeneration or a desired temperature of the regenerated catalyst or a desired regeneration zone temperature. In the 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 desired result to determine whether a further portion of the CO oxidation promoter is required. If after introducing a small proportion of the promoter in the generation zone, the measured concentration

_{r) Ati} 709831/0982

tration 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 nothing is within the predetermined range, a second part of the promoter, i.e. 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, each over a relatively short period of a few minutes to a few hours, allowed the operating personnel a more precise control and monitoring of the operation of the regeneration zone to achieve the desired Result. When adding the promoter in several increments the total amount of promoter is within the ranges given above. When the changeable that controlled is a dilution phase temperature, e.g. an exhaust gas temperature, the CO oxidation promoter can be combined with a diluent gas to control the temperature below a predetermined value to enable. The diluent gas is usually oxygen-containing Regeneration gas used. As soon as the measured variable is within the predetermined range for this variable or below, the promoter becomes continuously or intermittently in the required Extent is added to keep the measured variable within the predetermined range. The amounts of promoter which are required to be a changeable within a Maintaining a predetermined range can change from plant to plant and they are best done by observation and experience in the operation of the plant concerned, but it has been shown that the amount of promoter, which on a medium daily basis to maintain a change

70 9 831/0982

BATH ORIGINAL

lichen within a predetermined range is required, about 0.005 to about 10 parts-per-million by weight des circulating catalyst stock, based on elementary

Metal, corresponds.

Further embodiments of the decay are special independent control methods for use after the initial start-up of the fluid catalytic cracking process and after a useful stationary one Mode of operation of the process has been achieved. In particular, the invention provides in one embodiment a process for the catalytic cracking of a hydrocarbon feed stream the coke-contaminated catalyst and oxygen-containing regeneration gas in one under oxidation conditions Held regeneration zone are passed and coke to produce regenerated catalyst and an exhaust gas containing CO »and CO is oxidized, a Operation for controlling the CO concentration in the exhaust gas within a predetermined CO concentration range. In another embodiment, the invention provides one such method, an operation for controlling a regeneration zone temperature within a; predetermined Area. According to 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 Area. Such control methods can be used by the operating personnel independently of one another. For example, in one case, the operational management in 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 from a metallurgical point of view the regeneration zone, the regeneration zone temperature

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Allow for temperatures and the extent of regeneration that result when controlling the CO concentration. 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 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 which is stoichiometrically sufficient to convert at least part of the carbon monoxide into carbon dioxide. As already mentioned, the order in which they are fed is important in order to avoid the risk of afterburning. 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 (50 psig). 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 sensor temperature is measured and compared with the specified regeneration zone temperature range, or a regenerated catalyst is used for determination the actual residual carbon concentration is analyzed and the latter is compared with the ttest carbon concentration range to be observed. Thereafter, the promoter is supplied to the pegeneration zone in such amounts,

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that either the CO concentration or a regeneration zone temperature or the residual carbon concentration are maintained within their predetermined ranges. The amount of promoter initially supplied to the regeneration zone is preferably added in small increments, as explained above, until the desired result is achieved. The sum of these increments corresponds to from 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 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 fluidized catalytic cracking processes using the process The invention is used is not of critical importance, rather any types of conventional cracking catalysts or intended for use in the fluidized catalytic cracking process, both the amorphous catalysts as well as crystalline aluminosilicate catalysts as well as mixtures of the two types. Of the two general types of cracking catalysts, those are crystalline Catalysts comprising aluminosilicates because of the reduced coke yields and the increased yields of gaseous and liquid products that they produce as compared to amorphous catalysts. Since when using the Process of the invention carbon monoxide as a fuel in addition to the coke oxidized within the regeneration zone and at least part of the heat of the CO combustion within the rtegeneration zone is obtained, the cracking section of the

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fluid catalytic cracking process can now be as selective for more valuable products as the operating conditions the hydrocarbon conversion zone and the cracking catalyst allow. The operating conditions of the hydrocarbon Conversion zones are accordingly selected and based on maximum yields of gaseous and liquid products they usually include a temperature within the range of about 420 to about 600 C, pressure within the range from about atmospheric pressure to about 4.5 atm (50 psig), a catalyst / oil ratio from about 3 to about 20 and a hydrocarbon residence time in contact with the catalyst of from about 1 to about 30, and preferably from about 1 to about 10 seconds. Those in fluid catalytic cracking processes using the process of the invention The input materials used need not differ from the input materials used in operations can be used without using the process of the invention and can be any conventional hydrocarbon feedstock include, for example, heavy gasoline, gas oils, light and heavy distillates, residual oils and the like.

The method of the invention is further illustrated below by means of examples and comparative experiments, but it is not indicated on the particular promoters, concentrations of promoters, or operating conditions Methods of introduction into the regeneration zone are limited.

BeisDiel 1

This example describes investigations into the processes carried out in a semi-technical test facility in the regeneration one of a catalytic fluidized bed cracking plant, the tests being carried out to determine the effectiveness of adding a liquid to the

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contains low concentrations of certain promoters, to the regeneration zone of the catalytic fluidized bed cracking plant in order to reduce the concentration of CO in the exhaust gas. The tests were carried out using a vertical tubular vessel, the upper end of which was provided with a porous stainless steel filter to thereby hold the catalyst sample placed in the vessel during the sequence of operations within the vessel, and the lower end of which was an inlet means for the fluidizing medium, nitrogen or air, and an introduction device for the liquid containing the promoter. Means were also provided to heat the vessel to a constant temperature, and a chromatographic device was used to sample and analyze the exhaust gas from the vessel for CO, CO2 and O ₂ , so that in each case the instantaneous 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 containing about 0.9 Containing weight percent coke. The coke had been deposited on the catalyst by 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 operations has been enforced was.

In experiment 1, no liquid containing promoter was introduced into the vessel during the sequence of operations; the experiment was used to provide a basis for comparison for further experiments in which the procedure according to the invention Was applied, carried out. A 500 g sample of the consumed Catalyst was filled in the vessel and fluidized with nitrogen; the latter stepped at the bottom of the jar

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a. At the same time the device was brought to a temperature heated to 593 ° C. At a fixed point in time, the nitrogen was replaced by air, thereby oxidizing the Coke initiated. The exhaust gas from the vessel had the CO concentrations given in Table I below, determined by the chromatographic apparatus at various levels 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

Time,
Minutes CO in the dry
Exhaust, % CO- / CO-
Ratio 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 manner as Experiment 1, except that 15 seconds after switching the fluidizing nitrogen to the feed of air and while an increase in CO concentration was observed, 30 ml of dilute chloroplatinic acid solution (H-PtCl,) were injected into the vessel. The solution had been prepared by diluting chloroplatinic acid, which was about 28.6 percent by weight Pt, with distilled water to form dilute chloroplatinic acid at 0.1 mg Pt / ml. This amount of chloroplatinic acid corresponds to about 6.0 parts by weight

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per million of 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 In the experiment, the exhaust gas had the following compositions!

Table II

Regeneration zone of the experimental facility, experiment 2, Dilute chloroplatinic acid, 0.1 mg Pt / ml

CO concentrations in the exhaust gas

Time, . CO in dry CO2 / CO minutes exhaust gas,% ratio

1 1.7 9.3

2 <0.1> 100

3 <0.1> 100

The carbon monoxide concentrations are much lower and the CO / CO ratios are much higher than the corresponding Values in experiment 1 for the same time periods. To see how quickly the platinum is reducing its effectiveness loses the CO concentration, the regenerated catalyst from Experiment 2 was used for further cycles in an experimental hydrocarbon reaction zone and then in the Regeneration zone used without the addition of promoter. After the first three more cycles through the hydrocarbon reaction zone and the regeneration zone was made by burning coke essentially no CO formation observed, but a small amount of CO was in by the start of the fourth cycle was present in the off-gas, but this amount was considerably less than the amount in Experiment 1 which did not use a promoter became.

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 that the

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Liquid containing promoter was added to the vessel immediately before the fluidizing nitrogen switched to air became. In this experiment, 25 ml of the more dilute chloroplatinic acid, equivalent to about 0.5 parts-per-million by weight of the catalyst, based on metallic platinum, is introduced into the vessel. The solution was made by diluting a portion of the solution used for Experiment 2, which contained 0.1 mg 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, experiment 3, Dilute chloroplatinic acid, 0.01 mg Pt / ml

CO concentrate ions in the exhaust gas

Time, minutes

1 2

Albeit the reduced promoter range used in this experiment seemed to lead to 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 was found during the regeneration stage. After three cycles, the catalyst apparently produced about two thirds as much CO as it did during run 1 without addition generated by promoter.

In experiment 4, 25 ml of a solution of chlorine

CO in the dry co ₂ / co- Exhaust, % , Relationship 0.6 20.8 XO, 1 > 100 <0, 1 > 100

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palladium acid in water containing 0.1 mg Pd / ml, accordingly about 5 parts-per-million by weight of the catalyst sample, calculated as Pd metal, in the vessel 15 seconds after switching injected into air by the fluidizing nitrogen, thereby initiating the combustion. Within After two minutes, the CO concentration in the exhaust gas fell to less than 0.2 percent by volume.

Example 2

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

The catalytic fluidized bed cracking plant used for the investigation processed about 124 m / hour (18670 barrels / day) of a mixture of vacuum and coker gas oils and had a circulating catalyst inventory of approximately 54500 kg (60 tons) of zeolite-containing catalyst. The attachment was brought into a constant operating state under typical operating conditions without any effort a partial or essentially complete reduction in the CO concentration in the exhaust gas were directed and without the presence a CO conversion promoter in the regeneration zone. A number of relevant operating conditions of the process, prior to adding a promoter to the regeneration zone, are compiled in Table IV below.

There was then 2 liters of a solution of chloroplatinic acid in water over a period of 2-3 minutes pressed from a cylinder into the regeneration zone, through a nozzle located in the regeneration zone for

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Density determination. The diluted chloroplatinic acid solution was prepared by diluting 61.4 g of a concentrated one Chloroplatinic acid solution with a content of 28.637 percent by weight Pt per 2 liter volume using distilled water. The introduction of this amount of solution into the regeneration zone means a promoter feed correspondingly approximately 0.32 parts-per-million by weight circulating catalyst inventory based on metallic platinum. The regeneration zone responded almost immediately to this encore; the CO concentration in the exhaust gas decreased to about half the CO concentration before the introduction of the solution and the temperature of the dense phase the regeneration zone rose by about 25 ° C above the temperature before introducing the solution. No other operational changes were made to the process. A compilation of the operating conditions after this first addition of the solution can also be found in Table IV.

Several hours later, a minor amount of solution containing promoter equivalent to about 0.13 parts-per-million by weight of the circulating catalyst inventory based on metallic Pt was added to the regeneration zone in the introduced in the same way as the first addition. Apart from the addition of the promoter, there were no other operational changes of the procedure. A summary of the operating conditions shortly after this second addition is also given in Table IV below.

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MD

Table IV

Addressing the regeneration zone of a large-scale catalytic Fluidized bed cracking system on the addition of promoter

Selected operating conditions

Beginning, Towards Towards without giving of giving of Promo 0.32 wt. 0.1 3 wt. torzu share-ever- share-ever- gift million million

Temperatures, C

Regeneration zone, dense phase

Regeneration zone,
phase

diluted

Regeneration zone, exhaust gas hydrocarbon reaction zone United charging

Exhaust gas composition, vol .-% CO

COj / CO ratio

Residual carbon on regenerated catalyst, wt% 0.30

Fresh feed supply, m / h return material admixture,

m ³ / h

Air supply, m / second

124 11 15

681

661 687 667 678 510 511 328 328 10.5 5.9 10.8 12.8 0.0 0.0 1.03 2.17

0.16

124
11
15th

713

717 703 511 329

17.1

0.0

12.2

0.06

124 11 15

As can be seen from the values in Table IV, the CO concentration in the exhaust gas decreased from 10.5 percent by volume before Add promoter solution to 5.9 volume percent after adding the first amount of solution (0.32 parts by weight per million pt) and to 1.4 volume percent after the addition of the second amount of solution (0.13 parts-per-million pt). The residual carbon on the regenerated catalyst increased from 0.30 weight

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percent to O, 16 percent by weight after the addition of the first amount of solution, and then to 0.06 weight percent after the addition of the second amount of solution, while the temperature in the dense phase of the regeneration zone of 655 ° C to 681 ⁰ C and then to 713 ° C after the addition of the specified amounts of solution increased. Other regeneration zone temperatures also rose, but not as much as the dense phase temperature.

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, referred to below as test 1, was carried out for the purpose of comparison with subsequent investigations after the addition of promoter solution to the regeneration zone. In the course of 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 per million by weight, based on the circulating catalyst inventory and calculated as metallic Pt, contained in the im Example 2 described manner added. 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 . Then, during steady-state operation, when the CO was substantially completely burned within the regeneration zone in the presence of the mixture of CO conversion promoter and regenerated catalyst, test 2. At the time of test 2, the total amount of dilute chloroplatinic acid introduced into the regeneration zone was carried out the C0 oxidation promoter in an amount corresponding to about 0.9 parts by weight

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per million, based on the circulating catalyst inventory and calculated as metallic platinum.
Test 2 was run at essentially the same feed line and pressures in the regeneration zone and hydrocarbon reaction zone as Test 1. No action was taken to bring about the same level of conversion as Test 1 before beginning Test 2, nor have been making any efforts on it
directed to achieve the flow rate of the air needed
to optimize an essentially complete CO conversion. Relevant results of Test 1 and Test 2 are summarized in Table V.

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Table V

Comparative studies on the catalytic fluidized bed: · cracking before and after addition of CO conversion promoter

Test 12

Before after

Processing conditions

Hydrocarbon Reaction Zone Temperature, ⁰ C Combined Feed, Temp., ⁰ C

Regeneration zone

Temperature of the dense phase, the dilute phase temperature ⁰ C, ⁰ C exhaust gas temperature, ⁰ C

Carbon on the regenerated catalyst, wt% 0.28 0.11

Exhaust gas analysis, vol .-%

510 505 328 313 656 696 661 699 667 710

co ₂ 10.5 14.1 CO 9.6 <ίθ, 1 ° 2 0.0 3.5 COj / CO ratio 1.09 > 140 Product yields C ₂ and lighter components,% by weight 2.7 2.4 Propylene,% by volume 8.5 8.2 Propane, vol .-% 2.5 2.5 Isobutane, vol .-% 6.1 5.5 η-butane,% by volume 1.7 1.6 Butenes,% by volume 9.1 9.2 C ₅₊ gasoline, vol .-% 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,% v / v 79.7 78.0

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A comparison of the test results shows a reduction in the CO concentration of the exhaust gas of 9.6 percent by volume to 4 0.1 volume percent, a reduction in residual carbon on the regenerated catalyst from 0.28 weight percent to 0.11 weight percent, giving better catalyst regeneration indicates, and a general increase in regeneration zone temperatures of about 38 to 44 C when using the method the invention. Although the temperatures of the hydrocarbon reaction zone are not quite the same, the recovery has some of the heat of CO combustion within the regeneration zone in Test 2 allows a significant reduction in the temperature of the combined feed. Although the conversion in Test 2 was about 1.7% lower than in Test 1, a comparison of the yields shows that Test 2 achieves more 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 for Test 1, and despite the 1.7% lower conversion in Test 2 than Test 1, the gasoline yield was that Test 2 with 57.4 percent by volume is approximately the same as in test 1 with 57.6 percent by volume. In the case of induction With the same conversion, a significantly higher gasoline yield is achieved when using the process of the invention.

Long-term operations with the same large-scale plant showed that essentially complete conversion of CO can be sustained if the average daily amounts of promoter solution are introduced into the regeneration zone, the promoters 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 significant proportion of the Promoters remains on the cracking catalyst. For example

709831/0 9 82

was at a time when a total amount of chloroplatinic acid solution introduced with a total content of promoter corresponding to 75 g of platinum in this large-scale plant a sample of the catalyst in equilibrium was withdrawn from the system and checked for its platinum content analyzed. The value determined from this sample was 1.0 parts-per-million platinum. When the entire 75 g Platinum fed into the facility evenly distributed among the 54,500 kg (60 tons) of catalyst inventory if this were 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 it shows investigations into the chemical instability of a solution of chloroplatinic acid in a mixture of water and a common freezing point depressant for water, viz Ethylene glycol. Chloroplatinic acid containing 25.46 percent by weight Pt was in a mixture of equal parts by weight of technical grade ethylene glycol and water, one is distilled water and the other is tap water, dissolved to prepare two solutions, each 0.045 percent by weight Pt included. 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 are flowable at -29 ° C Solutions remained, but they did not have the desired chemical stability for 30 days at 63 ° C; a black precipitate formed in about 11 days at 22 ° C and in only 0.7 hours at 63 ° C. The black precipitate was separated by centrifugation, washed with water and analyzed for its platinum content. The elemental Pt content of the black precipitate was 94% and a chemical one

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Electron spectroscopic analysis indicated the presence of mainly metallic Pt (Pt °) with about 5% PtO. The platinum recovery from the precipitate, the flasks and the 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 ⁺ present in the chloroplatinic acid has apparently been reduced to Pt ° and the ethylene glycol has been oxidized. Ethylene glycol oxidation products were not identified.

Table VI

Stability of chloroplatinic acid in a mixture of ethylene glycol and water

... days to the formation of precipitation

Type of -

Sample water ⁰ -29 C 22 ° C 43 C 63 ° C

1 distilled soluble ^ 11 4 0.7

2 pipe soluble ~ 11 0.7 0.7

Example 5

This example shows studies on the freezing point and chemical stability at temperatures of -36 ° C, 22 ° C and 63 ° C for ten solutions of chloroplatinic acid with a concentration corresponding to 0.045 percent by weight Pt in various undiluted primary, secondary or tertiary alcohols of reagent quality or Mixtures thereof. A temperature of -36 ° C was chosen to the coldest temperatures invoice ZV wear that might occur at the site of a plant; the temperature of 22 ^C C corresponds to average ambient conditions; the temperature of 63 ° C was chosen in order to record average or possibly occurring storage conditions (in and outside of rooms or deer parents). The time is up, in days up to

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Mr

a black precipitate, most likely mainly made of metallic platinum, was observed for any temperature detected. The results are shown in Table VII below.

The chemical stability of chloroplatinic acid is best with saturated aliphatic primary alcohols, with the exception of methyl alcohol, and worse for them saturated aliphatic secondary and tertiary alcohols. In addition to a lack of suitability due to poor chemical The stability of the solution of chloroplatinic acid in 2-methyl-2-propanol was solid at -36 ° C. A classification of the chloroplatinic acid solutions in various solvents in the order of decreasing chemical stability at 63 ° C gives: 2-ethyl-i-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).

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Table VII

σ co αο to

solution

Resistance of chloroplatinic acid in different solvents at different temperatures

solvent

Art

1 Methanol -97 2 Ethanol -112 3 1-propanol -127 4th 2-propanol -85 5 1-butanol -89 6th 2-butanol -89 7th 2-methyl-2-propanol 25th 8th 1-hexanol -51 9 2-ethyl-1-hexanol -70 10 Et: anol + 1-butanol (1: 1)

Enamel ,. _{Boiling iX} Flammr. ,. point, ⁰ C ¹⁾ point, ⁰ C ¹⁾ point ² ) ° C ^1}

117

100

83

157

184

12 12 16-29

12-16 ₃₇ 3)

24 11 74 85 days until precipitation forms

-36 ° C
4)

22 ° C

14th

n.b.

Liquid> 61

Liquid> 61

n.b. 7th

Liquid> 63

n.b. · 56

Solid 22

Liquid> 56

> 60> 60

n.b.

> 48

6 3 ° C

0.25

44

> 58

50 2

13th

42

> 60

> 48

1) Literature values for the melting point, the boiling point and the flash point

2) Closed cup flash point, Cleveland

3) Penske-Martens determinations with closed beaker

4) nb « not determined

5) Chloroplatinic acid concentration in each solution corresponding to 0.045 percent by weight Pt

00

ro

Example 6

This example describes investigations in the regeneration zone of a pilot plant, which were carried out to determine the effectiveness of a solution containing chloroplatinic acid in 1-butanol in reducing the concentration of CO in the exhaust gas. The tests were carried out using the test device explained in Example 1. As in Example 1, provisions were made to heat the device to a constant temperature, and samples of the exhaust gas were continuously taken from the vessel by means of a chromatographic device and analyzed _{for CO, CO 2} and O _2. A chromatographic trace was recorded for CO, CO ₂ and O ₂ so that instantaneous analyzes were available to characterize the combustion of CO during the test. A specific CO ₂ / CO ratio, hereinafter referred to as the C0 ₂ / C0 minimum ratio, was determined from the chromatographic lines for each test up to 3 minutes after initiation of the combustion), furthermore the CO ₂ concentration was determined at the moment of the maximum CO concentration and then the CO ₂ / CO ratio for the concentrations determined in this way was calculated. This ratio is referred to as the C0 ₂ / C0 minimum ratio, since in many such regeneration tests it has been observed that if the instantaneous COj / CO ratios are plotted against the elapsed time, a curve results for each test which goes through a minimum, and the CO ₂ / CO ratio at this minimum has a value as calculated by the method explained above. It has been found that this _{minimum CO 2} / CO ratio best characterizes the effectiveness and efficiency of any solution containing a CO promoter for catalysis of CO combustion.

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The tests were carried out on 500 g samples of equilibrium zeolite-containing fluidized bed cracking catalyst which had previously been brought to a spent ¹¹ state by passing a gas oil feed through the equilibrium catalyst sample in a pilot-scale hydrocarbon reaction zone operated at standard conditions with a predetermined sequence of operations was directed. Each sample of the spent catalyst contained approximately 0.9 weight percent coke.

In test 1, no promoter-containing solution was added. This test was conducted to provide a basis for comparison with a subsequent test using a promoter-containing solution. A 500 g sample of the spent catalyst was placed in the vessel and fluidized with nitrogen which entered the bottom of the vessel while the device was heated to a temperature of 593 ° 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 analyzed for CO-, CO and O- with the chromatographic device and the C02 / C0 minimum ratio was calculated _{from the lines for CO 2 and CO.} To determine a measure of the reproducibility of the results obtained by this test method, the test was repeated a total of four times with separate samples of the spent catalyst. The _{minimum CO 2} / CO ratios ranged 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 except that immediately before Switching the fluidizing nitrogen to air a 25 g sample of a solution of chloroplatinic acid in 1-butanol into the Regeneration zone was injected. The concentration of

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Chloroplatinic acid in the sample was equal to 0.008 weight percent Pt and the amount of platinum in the sample was 2 mg Pt, ie 4 parts-per-million by weight with respect to the 500 g catalyst sample. The result was a C0 ₂ / C0 minimum ratio of 52.1 * operated in further cycles. Specifically, to complete another cycle, the mixture in the semi-industrial scale hydrocarbon reaction zone was "consumed" in the manner described above, and then the regeneration zone test was repeated, but without adding any further amounts of promoter solution. At the end of the seventh cycle, the _{minimum CO 2} / CO ratio for the particulate mixture was 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 the use of a promoter solution

C0 ₂ / C0 minimum ratio 8e cycle: _1 2 3 4__ _J> 6_ 7

Test 1; no application of 3.3- - - - - -

Promoter solution _

z, 3. - - - - - -

Test 2; 25 g solution of chlorine-52.1 - - · - - -41.5 platinic acid in 1-butanol
with a content of
0.008 wt% Pt

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

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Claims (16)

Claims 1. Process for regenerating coke contaminated Catalysts with simultaneous carefully controlled combustion of carbon monoxide, characterized in, that he (a) Coke contaminated catalyst into a regeneration zone introduces, (b) a carbon monoxide oxidation promoter in the regeneration zone regardless of the catalyst contaminated with coke, in an amount to promote the combustion of Brings carbon monoxide to carbon dioxide, (c) oxygen-containing regeneration gas into the regeneration zone in an amount sufficient to burn coke off the coke-contaminated catalyst and to display introduces excess oxygen to bring about the desired level of carbon monoxide combustion, (d) a first part of the oxygen-containing regeneration gas with the coke-contaminated catalyst in the regeneration zone under oxidation conditions for removal of coke 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 oxidation promoter, implements and (e) Simultaneously the exhaust gas and a second part of the oxygen-containing one Regeneration gas with the carbon monoxide oxidation promoter in the regeneration zone in the presence of regenerated catalyst brings into contact with the oxidation conditions, and thereby (1) a controlled Amount of exothermic heat of reaction for operation 7 0 a8 3 1/0982 ORIGINAL INSPECTED the regeneration zone and (2) the amount of carbon monoxide in the exhaust gas. 2. The method according to claim 1, characterized in that the carbon monoxide oxidation promoter in the step (b) in the form of a solution in a solvent. 3. The method according to claim 2, characterized in that there is a solvent, the water or a liquid Comprises or consists of hydrocarbon is used. 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 having 2 to 8 carbon atoms per molecule and freezing points of O ⁰ C (32 ° F) or below, used. 5. The method according to claim 4, characterized in that the primary alcohol is 1-butanol or 2-Ä "ethyl-1-hexanol used. 6. The method according to any one of claims 1-5, characterized in that the carbon monoxide oxidation promoter introduces into the regeneration zone in such an amount that exhaust gas contains the carbon monoxide in an amount equal to or less as a predetermined amount is generated. 7. The method according to any one of claims 1-5, characterized in that the carbon monoxide oxidation promoter in the regeneration zone in step (b) in such an amount that a sufficient amount of exothermic The heat of reaction is released in order to increase the mean combustion temperature in the regeneration zone to a level in which a regenerated catalyst, the remaining carbon 7098 3 1/0 982 substance in an amount less than or equal to a predetermined one Value is generated. 8. The method according to any one of claims 1-5, characterized in that the carbon monoxide oxidation promoter 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 catalyst to a predetermined level is released. 9. The method according to any one of claims 1-5, characterized in that the amount of in step (b) carbon monoxide oxidation promoter introduced into the regeneration zone is set to a value sufficient to insure that substantially all of the exothermic combustion heat released by carbon monoxide is released in the presence of regenerated catalyst, and thereby allows the temperature of the exhaust gas to be controlled below a predetermined level. 10. The method according to any one of claims 1-5, characterized in that the amount of in step (b) carbon monoxide oxidation promoter introduced into the regeneration zone in connection with one of the regeneration zones supplied Diluent gas amount adjusts to control the temperature of the outflowing exhaust gas below a predetermined Allow height. 11. The method according to any one of claims 1-10, characterized in that there is 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 there is a carbon monoxide oxidation promoter from 709831/0982 Group used 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-per-million by weight of 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 each 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 oxidation conditions with a temperature of 590 to 790 ° C are used in the regeneration zone (1100-145O ° F) and pressures from atmospheric to 4.5 atm (50 psig). 16. The method according to any one of claims 1-15, characterized in that the regeneration zone Carbon monoxide oxidation promoter in an average daily amount corresponding to 0.005 to 10 parts-per-million by weight des circulating catalyst stock, based on elemental metal, feeds. 709831 / Π982