CS223821B2 - Method of cyclic fluidous catalytic cracking e,g,catalytic cracking in fluidous,ev,swirling phase of hydrocarbon materials with contents of weight 0,2 till 6 percent sulphur - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for catalytic cracking with reduced release of noxious gases, and more particularly to a cyclic process for cracking in the mobile or in the animal phase. The process is suitable for the treatment of hydrocarbons containing organic sulfur compounds and leads to a significant reduction in the proportions of carbon monoxide and sulfur oxides in the waste gases from the recovery plant.

The cracking catalyst, which is relatively largely deactivated during the cracking of the hydrocarbons in the reaction zone by carbonaceous deposits, commonly referred to as coke, is continuously discharged from the reaction zone. The catalyst so worn leads from the reaction zone to the stripping zone where it is washed out and separated from the catalyst by the depletable carbonaceous deposits, and the catalyst is then led to the recovery zone where catalyst activity is restored by removing residual carbon deposits by burning coke in the oxygen-containing gas stream. the formation of carbon monoxide and carbon dioxide. The hot, regenerated catalyst is then continuously fed back into the reactor to repeat the cycle.

The cracking catalyst, which is relatively largely deactivated during the cracking of the hydrocarbons in the reaction zone by depositing carbonaceous deposits, usually referred to as coke, is continuously discharged from the reaction zone. The catalyst so worn is passed from the reaction zone to the stripping zone where it is washed out and separated from the catalyst by the evacuable carbonaceous deposits, and the catalyst is then fed to the regeneration zone where the catalyst activity is restored by removing non-ejectable and non-erasable carbon deposits. oxygen, producing carbon monoxide and carbon dioxide. The hot regenerated catalyst is then continuously fed back into the reactor to repeat the cycle,

In the catalytic cracking, there are problems with the incomplete combustion of carbon monoxide to carbon dioxide in the regeneration zone, and thus a noticeable amount of carbon monoxide in the waste or flue gases from the regeneration zone is leaked. In addition to the unwanted leakage of carbon monoxide into the atmosphere, carbon monoxide and residual oxygen in the waste gases from the regeneration zone tend to react together, and the flames in the ducts and smoke outlets, and of course these devices can be damaged by excessively high temperatures.

Furthermore, when the sulfur-containing feedstocks, i.e., the oil fraction, containing organic sulfur compounds, are fed to a mobile catalyst-type cracker, the coke, which is deposited on the catalyst particles, contains sulfur. When the coke-deactivated catalyst is recovered, coke is burnt from the catalyst surfaces, and in this combustion process, sulfur is converted into sulfur dioxide along with a small amount of sulfur trioxide, and these are passed into the gas stream from the recovery zone. When cracking a highly polluted sulfur feed, sulfur oxides often leak in an amount of approximately 1,200 parts per million (ppm).

Standardized conditions with regard to ambient air pollution have been established for the discharge of carbon monoxide as well as fly ash leakage, and similar measures for other waste gases such as sulfur oxides and especially sulfur dioxide should be expected in the short term. For this reason, great attention is paid to the problem of reducing the content of various escaping gases, as well as fly ash from various combustion processes and regeneration zones in connection with cracking equipment. To reduce the leakage of these gases, it is therefore necessary to select processes which are effective without at the same time reducing the efficiency or selectivity of the catalyst. In addition, unwanted leakage of harmful gases must not be replaced by another problem, such as increased fly ash leakage or increased operating costs. In view of these requirements, the desirable reduction of sulfur oxides leakage in the oil cracker is achieved by using a cracking catalyst, which is modified to minimize leakage of both carbon monoxide and sulfur oxides, catalyst efficiency, stability and abrasion resistance. under normal cracking conditions in existing or new crackers remains unchanged.

While we usually avoid the use of metals in cracking catalysts and is believed to be problematic to crack metal-containing paint in the presence of cracking catalysts, South African Patent 7924/72 and its corresponding U.S. Patent 3,909,392 are described in more detail below. dealt with the overall analysis that combustion catalysts or promoters can be used together with cracking catalysts within the regeneration zone in the presence of a metal rod, grid, mesh or screen in the combustion zone, as well as metal compounds which can be moved, especially powdered transition metal oxides such as iron (III) oxide, manganese dioxide and rare earth oxides that are added to the catalyst to be added, or are limited to regeneration plants. Belgian Patent 826,266 discloses a process similar to that described in U.S. Patent 3,909,392, in which a catalytic cracking catalyst is used in physical association with a catalyst for accelerating the oxidation of carbon monoxide and is a metal with an atomic number of at least 20, and metals of groups IB, IIB and III to VIII of the Periodic Table of the Elements are mentioned as suitable oxidation promoters, in particular platinum, palladium, rhodium, molybdenum, tungsten, copper, chromium, nickel, manganese, cobalt, vanadium, iron, cerium , ytterbium and uranium. U.S. Patent No. 3,808,121 discloses the regeneration of a cracking catalyst in the presence of a carbon monoxide oxidizing catalyst and is maintained in the regeneration zone.

Belgian patent specification 7 412 423 discloses a cracking catalyst containing less than 100 ppm, calculated on the metal and based on the total catalyst, of at least one metal component of the metals of group V and VIL of period VIII. This group of catalysts leads to a particularly marked reduction in the carbon monoxide content of the flue gases from the catalytic cracking apparatus. The patent also relates to a molecular sieve catalyst that is prepared in the sodium cycle, sodium is exchanged for ammonium cations by ion exchange, after which the screen is impregnated with rare earth metals.

With regard to the release of sulfur oxides, various methods have been described for treating waste gases and possibly flue gases, such as scrubbing, chemical absorption, neutralization and chemical reactions and conversions, but all of these methods for the removal of sulfur oxides require space-intensive costly additional equipment, and this obviously increases both operating and investment costs. U.S. Pat. No. 3,699,037 discloses adding at least a stoichiometric amount of a calcium or magnesium compound, calculated on the amount of sulfur deposit on the catalyst, to the cracking cycle. This added material is to react with sulfur oxides, and is then to be removed in a very fine state from the cracking cycle in the form of fly ash material in the off-gas from the recovery plant. However, the continuous addition of such material noticeably increases operating costs. In the same way, U.S. Pat. Nos. 3,030,300 and 3,030,314 relate to a catalytic cracking process in which one or more boron, alkali or alkaline earth metal compounds are continuously added to a moving bed catalytic cracking cycle to form catalyst particles. with increased impact resistance as well as abrasion of surface surfaces. The catalyst particles comprise a silica-based or silica-based material with a microporous catalytically active core, provided with an adhering protective coating of glass, the substrate being silica and one or more compounds of boron, alkali metals and caustic earth metals.

U.S. Pat. No. 3,813,031 discloses a cyclic process of catalytic cracking in the moving or aging phase, whereby a reduced leakage of sulfur oxides in the off-gas from the recovery plant is achieved. The process operates with a catalyst on a molecular sieve with matrix or silicon oxide alumina. and the screen is impregnated with one or more of the kovůΑ group metal oxides. U.S. Patent Nos. 3,388,077, 2,409,390 and 3,849,343 disclose a method for treating a harmful off-gas stream comprising carbon monoxide and sulfur oxides. The method comprises contacting the stream with a catalytic composition comprising a porous and refractory support material, a catalytically active metal component, for example a platinum group metal or an alkaline earth metal group such as calcium, barium and strontium.

A brand new method has now been found.

BACKGROUND OF THE INVENTION The present invention relates to a cyclic process for catalytic cracking in the mobile or in the vapor phase with reduced leakage of sulfur oxides in waste gases from the recovery zone. In various embodiments, the invention also results in substantially complete combustion of the carbon monoxide in the reaction zone and absorption of the heat generated by such combustion on solid particles that are fed into the reaction zone and into the ejection zone before being returned to the recovery zone. The solid particles are essentially a molecular sieve cracking catalyst and a metal reactant; it may also be an amorphous cracking catalyst and solids which are substantially inert in the cracking of hydrocarbons.

The metal reagent can be incorporated into a molecular sieve cracking catalyst, amorphous cracking catalysts, and solid, substantially inert substances. This can be done either before or after the addition of substrate particles to the cracking cycle. The conditions of the cracking process are such that a solid metal and sulfur-containing compound is formed on the solid particles in the regeneration zone, and the sulfur-containing gas is discharged from the stripping zone.

When selecting catalysts to reduce the release of sulfur oxides from waste gases from the regeneration zone of the cracking process in the mobile phase, it is important that such catalysts not only have the ability to perform their special function, but also to fulfill this function satisfactorily over a longer period. Therefore, when looking for such catalysts, consideration should be given to the performance and stability properties of the catalysts. Effectiveness in this sense

S is a measure of the ability of a catalyst to reduce sulfur oxide leakage in waste gases from a regeneration zone at some accuracy, meaning conditions used, such as temperature, pressure, contact time, etc. Catalyst stability means a measure of a catalyst's ability to maintain its efficiency for a certain period of time. Stability refers to the time rate of parameter changes in terms of efficacy, the lower the rate, the more stable the catalyst. The stability or stability of the catalyst should be such that the efficiency of the catalyst does not change over an extended period of operation.

These key features are easier to achieve if the active agent used to achieve a reduced leakage of sulfur oxides, i.e. a metal deed according to the present invention, is added to the cracking process cycle and incorporated in situ into solid particles than would be the case in in the case of a molecular sieve-type cracking catalyst, in which case the metal reagent is added to or admixed with in the preparation of the catalyst. It has been shown that introducing or adding a metal reagent to the cracking process cycle as compared to blending into the molecular sieve cracking catalyst during the preparation of the cracking catalyst results in a greater reduction in the amount of sulfur oxides leaking in the waste gases from the recovery zone. The addition of the metal reagent to the cracking process cycle is also advantageous in that it controls and controls the potentially harmful effect of the metal reagent on the cracking rate, since the rate and / or amount of metal reagent introduced into the cracking cycle can be varied. Also, the metal reagent, which would be premixed with the cracking catalyst, could also be lost when the cracking catalyst is abrasion in the form of fine particles. Adding the metal reagent to the cracking process cycle and introducing it into the solid particles in situ allows the desired amount of the metal reagent to be maintained on the outside or in accessible locations of the cracking catalyst.

Accordingly, the present invention provides a process for cyclic fluidized catalytic cracking or catalytic cracking in a fluidized or fluidized bed of hydrocarbon materials containing 0.2-6% by weight of sulfur in the form of organic compounds, wherein the feed is cracked in a fluidized or fluidized reaction zone. Cracked catalyst particles of molecular sieve type, catalyst particles deactivated with sulfur and carbon deposits are separated from the reaction zone product and introduced into a stripping zone where the volatile deposits from the deactivated catalyst are stripped off with stripping gas, stripped catalyst particles are separated from the stripping product and transferred to the regeneration zone and by burning the de-stripped deposits containing sulfur and carbon with the oxygen-containing gas, the regenerated catalyst particles are recovered from the They separate from the gas from the regeneration zone and return to the reaction zone, characterized in that the solid particles containing the cracking catalyst of the molecular sieve type are cycled together with the metal reactant, the metal reactant being at least one metal in free form or in the form a compound selected from magnesium, calcium, strontium and barium, wherein the amount of the metal reactant is sufficient to absorb at least 50% of the sulfur oxides that develop when the sulfur and carbon deposits in the regeneration zone are combusted and wherein the metal reactant is introduced into the cracking cycle in liquid form or in the form of particles of solid matter different from the cracking catalyst of the molecular sieve type, the feed is cracked in the presence of circulating particles at a temperature of 454 to 649 ° C, the volatile separated products from the circulating particles are stripped At a temperature of 454 to 649 ° C with steam-containing stripping gas at a weight ratio of steam to cracking catalyst of 0.0005 to 0.025 per unit of time, the sulfur and carbon-containing deposit is burned from the stripped circulating particles at 566 to 788 ° C. absorb at least 50% of the sulfur oxides produced by the combustion of sulfur and carbonaceous deposits in the regeneration zone, gas containing molecular oxygen and traces of sulfur oxides is removed from the regeneration zone and absorbed sulfur oxides are removed as volatile components from the reaction and / or stripper zone.

Accordingly, the present invention provides an improved method of cyclic catalytic cracking in a moving or animal phase by cracking a hydrocarbon feed containing organic sulfur compounds in a reaction zone with moving or moving catalyst particles using homogeneous or inhomogeneous recoverable and moving solid particles containing a metal reagent; A molecular sieve-type cracking catalyst comprising a cracking catalyst matrix and crystalline aluminum silicate, distributed over a matrix, wherein the cracking catalyst is simultaneously deactivated by sulfur-containing carbonaceous deposits and deposits. The particulate solids are separated from the discharged stream of cracked hydrocarbons from the reaction zone and passed to a stripping zone where the deactivated catalyst is stripped of expulsive carbonaceous deposits and deposition by contact with the stripping gas. The movable solid particles are then separated from the gaseous effluent stream from the stripping zone and fed to a regeneration zone where the deactivated catalyst is recovered after the volatilized components have been ejected by incinerating the sulfur-containing non-ejectable carbonaceous deposits. They are in the form of a high efficiency catalyst to form carbon monoxide, carbon dioxide and sulfur oxides which react with the metal reagent to form a metal and sulfur containing compound. Moving or swirling solid particles containing the regenerated cracking catalyst are separated from the off-gas or the flue gases of the regeneration zone and returned to the reaction zone.

The improvement is that metal in the metal reagent is added to the cracking process cycle, the metal reagent is deposited on or incorporated into the solids during the cracking process cycle, further using a stripping gas containing steam to regenerate the deactivated cracking catalyst in at a regeneration temperature in the range where the metal and sulfur-containing compound is contained in the solid particles, stable, as well as in the supply of sufficient oxygen in the regeneration zone, which is conditioned by supplying an oxygen-containing gas stream to the regeneration zone, the bands contain molecular oxygen.

A suitable hydrocarbon feed for use in the process of the invention comprises about 0.2-6% by weight of sulfur as organic sulfur compounds. Advantageously, the feed comprises from 0.5 to 5% by weight of sulfur and in particular from 1 to 4% by weight of sulfur, the sulfur in the feed being in the form of organic sulfur compounds.

The molecular sieve-type cracking catalyst matrix is preferably a combination of at least two materials selected from the group consisting of silicon dioxide, lithium oxide, zirconia, titanium dioxide, magnesium oxide, thorium oxide and boric oxide, in particular a combination of silica and alumina. This cracking catalyst matrix preferably contains from 10 to 65% by weight and in particular from 25 to 60% by weight of alumina, preferably from 35 to 90% and in particular from 35 to 70% by weight of silica, and preferably from 0.5 to 50% and particularly up to 50% of crystalline aluminum silicate. The molecular sieve-type cracking catalyst preferably contains from 10 to 99.999 and in particular from 30 to 99.999% and in particular from 90 to 99.999% by weight of solids, the remainder being a metal reagent.

The metal reagent comprises at least one free or bonded metal element from the group consisting of magnesium, calcium, strontium and barium, compounds and mixtures thereof, and preferably the metal agent is selected from magnesium or calcium.

It appears that oxide or oxide of the metal element or metal elements of the metal reagent ¹ is substantially responsible for ab223821 sorption of sulfur oxides in the regeneration zone. For this reason, it is preferable to add the metal element or metal elements of the metal reagent to the catalytic cracking cycle in the form of oxide or oxides. In practice, however, it is sufficient to add to the cycle at least one of the suitable metal elements selected for use as the metal reagent. The metal element or metal elements of the metal reagent are activated to absorb sulfur oxides in the regeneration zone. Activation is believed to be the partial conversion or substantially complete conversion of the metal or metals of the metal reagent to the corresponding oxide or oxides. And this activation does not depend essentially on the precise way in which the metal elements are combined or bonded at the time of introduction into the cycle.

The metal reagent is present in the recovery zone in an average amount such that it is sufficient to absorb a major proportion of the sulfur oxides produced by burning the carbonaceous deposits containing the sulfur. Of the sulfur oxides thus formed, at least 50% and preferably more than 80% is absorbed by the metal reagent in the recovery zone. As a result, the concentration of sulfur oxides in the waste gases from the recovery zone of the process of the invention is in the range below 600-1000 parts per million (ppmv), and is preferably less than about 600 ppmv, and particularly less than about 400 ppmv.

The amount of metal reagent used, when converted to metal or metals, is preferably about 25 ppm to 7% by weight, especially 0.01 to about 5% by weight, and especially about 0.1 to about 0.5% by weight of the particles.

The metal reagent is not uniformly distributed on the solid particles. Accordingly, certain solid particles may contain less or greater amounts of the metal reagent than mentioned above, but on average, the solid particles contain the above-mentioned mean values of the metal reagent.

The deactivated catalyst, depleted in the stripping zone, is regenerated in the recovery zone at temperatures to form a stable metal and sulfur compound from the metal in the solids contained in the metal reagent and from the sulfur oxides. The regeneration temperatures are preferably about 638 to 732 ° C. The hydrocarbon feed is cracked under reaction conditions where the metal-sulfur compound contained in the solids reacts to form the metal sulfide in the metal reagent. The cracking temperature is preferably about 454 to about 649 ° C, and especially about 466 to about 593 ° C. The expellable deposits from the deactivated cracking catalyst are removed by treatment with a vapor-containing gas at temperature conditions in which the metal sulfide in the metal reagent reacts with water to form hydrogen sulfide gas. The ejection temperatures are preferably about 554 to about 649 ° C, and particularly about 466 to about 538 ° C. The weight ratio of steam to cracking catalyst of the molecular sieve type that is added to the stripping zone is preferably about 0.0005 to about 0.025, and in particular 0.0015 to about 0.0125. The waste gases from the reaction zone preferably contain at least 0.01% by volume and in particular at least 0.5% oxygen, in order to achieve the desired reduction of harmful gases in the discharged gases.

In one embodiment of the process of the invention, the metal-containing material in the metal reagent is an oil-soluble or water-dispersible compound and the metal reagent is incorporated into a molecular sieve cracking catalyst. In this case, the metal reagent is incorporated either into crystalline aluminum silicate, or into a crystalline aluminum silicate matrix, or into a molecular sieve-type cracking catalyst matrix. In this embodiment of the process of the invention, the solid particles may additionally comprise at least one constituent from the group of solids that are substantially inert under hydrocarbon cracking conditions and a cracking amorphous catalyst, whereupon the metal reagent is incorporated into such a constituent. In this embodiment, the compound to be introduced into the catalytic cracking cycle of the invention, which comprises a cracking reaction zone, a stripping zone and a regeneration zone, is preferably a metal salt. Examples are metal diketones and metal salts of carboxylic acids having 1 to 20 carbon atoms. A particularly preferred compound of this type is magnesium acetylacetonate.

In another embodiment of the process of the present invention, the metal reagent itself is in powder form, for example magnesium oxide, as the metal-containing material in the metal reagent. In another embodiment, the material is a supported metal reagent composition that is either an amorphous cracking catalyst or a solid that is substantially inert under cracking reaction conditions.

The invention therefore relates to an improved process for catalytic cracking in a moving or an agitated phase which is at the same time an improved process for regenerating the catalyst used in the catalytic conversion in a moving phase as well as an improved process for reducing sulfur oxides in waste gases from the cracking catalyst recovery zone. It also relates to the conversion of sulfur-containing hydrocarbon feeds in which the cracking catalyst is deactivated by depositing sulfur coke deposits on the surfaces of the cracking catalyst. The solid particles used in the process of the present invention, including cracking catalysts of the molecular sieve type, circulate in a mutually well dispersible physical relationship with each other through a cracking process cycle that includes a cracking zone, a stripping zone, and a recovery zone. The conditions used result in a reduction in the sulfur oxide content of the waste gases from the recovery zone.

The cracking catalyst and the metal reagent of the invention have different functions.

The cracking catalyst serves to catalyze the cracking reactions, while the metal reagent is substantially inert with respect to the cracking reaction or has very little effect on the catalytic conversion reaction under the conditions used. To reduce the content of sulfur oxides in the waste gases from the recovery zone, they then absorb the solid sulfur oxide particles in the recovery zone. The molecular sieve-type cracking catalyst often serves as such in the function of absorbing sulfur oxides. The metal reagent reacts with the absorbed sulfur oxides to form a metal and sulfur-containing compound, in particular to form a metal sulfate, especially an alkaline earth metal sulfate in solid particles. Assuming that the metal and sulfur containing compound is stable in the regeneration zone under operating conditions, it converts on the surface of the solid particles into a reaction zone and a stripping zone where it is reduced and separated as a sulfur-containing gas, particularly hydrogen sulfide.

Activity with regard to the reduction of leakage of sulfur oxides in the waste gases from the regeneration zone depends on the nature of the applicable ^one metal. With the usable metals in the metal reagent, no equivalent results are obtained as with the special metals which can be used in the metal reagent; reaction conditions also influence the results.

The solid particles according to the invention are finely divided and have a mean size of not more than 20 micrometers to 150 micrometers, so that they are in motion or in motion in a suitable embodiment. Suitable cracking catalyst matrices include silica and / or alumina. Other refractory metal oxides may be used, the choice of which is ultimately limited by their ability to regenerate effectively under selected reaction conditions. Clays can also be used as an additive to alumina. Preferred catalysts are mixtures of alumina and silica mixed with molecular sieves known as zeolites or crystalline aluminum silicates. Suitable cracking catalysts are characterized by a content of crystalline aluminum silicate which is sufficient to increase the cracking activity of the catalyst, said amount being ultimately limited by the possibility of effective regeneration under the reaction conditions. Crystalline aluminum silicates typically contain silica and alumina in a molar ratio of at least about 2: 1, for example about 2 to 12: 1, preferably about 4 to 6: 1. Crack catalysts on a silica support containing, for example, about 35 wt. up to about 90% by weight of silica and containing about 10 to about 65% by weight of alumina. Such catalysts may be prepared using any suitable method, such as milling, gel co-precipitation, and the like, provided that the finished catalyst is in a suitable physical form for vortexing.

Suitable molecular sieves include, of course, both natural and synthetic aluminum silicate materials such as faujasite, chabazite, "X" and "Y" type silicates, and ultra-stable, large porous, crystalline aluminum silicates, or materials containing them. When mixing, for example with silica and alumina, to form a catalyst for cracking oil, the molecular sieve content of the freshly prepared catalyst particles is suitably about 0.5 to about 50%, preferably about 5 to 50, by weight. The equilibrium mixture of molecular sieve and cracking catalyst may contain only 1% by weight of crystalline material. Crystalline aluminum silicates are usually available in sodium form or are prepared in this form. The sodium component is then usually reduced to as low as possible, usually below about 0.30% by weight, by ion exchange for hydrogen ions or precursors thereof, such as ammonium or polyvalent metal ions, including including calcium, strontium, barium and rare earth metals such as cerium, lanthanum, neodymium and rare earth metals found in nature, and mixtures thereof. The pore structure of the usable crystalline materials should be maintained under high temperature conditions during catalyst preparation, hydrocarbon processing and catalyst regeneration. Crystalline aluminum silicates are often characterized by a uniform pore structure of extremely small size, the mean pore diameter being about 0.6 to about 2.0 nm and preferably 1.0 to 1.5 nm.

Catalytic cracking of heavy mineral oil fractions is one of the main refining processes for converting crude oil fractions into desirable combustible materials such as high octane gasoline fuels and kerosene used for internal combustion and spark ignition machines. One example of catalytic conversion is a mobile or vapor phase catalytic cracking process wherein high molecular weight liquid hydrocarbons or their vapors are contacted with hot, solid and fine catalyst particles in either a moving bed reactor or a vortex catalyst. a bed or extended elongation reactor, and the mixture of catalyst particles and hydrocarbon is maintained at elevated temperature in a moving or animal state for a time sufficient to achieve the desired degree of cracking of the higher molecular weight hydrocarbon to form a hydrocarbon fraction, which corresponds to motor spirit and the usual distillates.

Suitable hydrocarbon feeds typically have a boiling point of 204 to 649 ^° C, a higher range than the gasoline or kerosene fractions, and the cracking is generally carried out at about 454 to about 849 ^° C. Suitable feeds include fractions petroleum boiling above the boiling range of kerosene and thus of gasoline such as light gas oils, heavy gas oils, vacuum oils, kerosene, decanted oils, residual fractions, reduced crude oils and circulation oils derived from any of the foregoing oils, as well as suitable fractions obtained from shale oils, from tar sands, synthetic oils, coal liquefaction products and the like. These fractions may be used as such or in any suitable combination.

The process according to the invention can be carried out in any cracking apparatus and according to any scheme, but is preferably carried out in a catalytic cracking system with a moving or fluidized bed, where most of the hydrocarbon conversion takes place in the diluted phase in the transfer line or in the ascending reactor system. using highly active catalysts and a relatively high flow rate. Preferably, the cracking takes place essentially exclusively in the upstream reactor and the subsequent dense cracking bed is not used for cracking. In a typical embodiment using cracking in an ascending reactor and gas oil conversion, the volumetric flow rate or volume ratio of total feed to fresh feed may be from 1 to about 3. The degree of conversion may be about 40 to 100% by weight and preferably maintained above 40 ° /. 60 to 90%. Conversion in this case refers to a percentage reduction in the weight of hydrocarbons boiling above 221 ° C at atmospheric pressure to produce lower hydrocarbons or coke. The weight ratio of the total cracking catalyst to oil in the ascending reactor may be about 2 to about 20 so that the dispersion that is in motion or vortex has a density of about 16.1 to 283 kg / m ³ . Preferably, the catalyst to oil ratio is maintained in the range of about 3 to about 20, preferably 3 to 7. The velocity of movement or turbulence in the ascending reactor may be 3.088 to about 30.48 m / s. The upstream reactor is generally characterized by a length to diameter ratio of about 25. During oil processing, a mixed temperature is maintained at the bottom of the upstream reactor, preferably 538 to 543 ^° C, to maintain a temperature of 510 ° C at the top of the reactor. . Essentially, higher temperatures are required for cracking residues and synthetic fuels. Under these conditions and assuming rapid separation of the worn catalyst from the discharged hydrocarbon vapors, the contact time between the catalyst and the hydrocarbons is very short. The contact time in the ascending reactor is usually 1 to 15 seconds, and preferably about 3 to 10 seconds. Preferably, short contact times are employed, since the greatest proportion of hydrocarbon cracking occurs during the first contact times, and undesirable secondary reactions can be avoided. This is particularly important if higher product yields and higher selectivity as well as lower coke formation are to be achieved.

Short contact times between catalyst particles and hydrocarbon vapors can be achieved in various ways. For example, it is possible to charge the catalyst at one or more locations along the length of the bottom or section at the bottom of the ascending reactor. In the same way, the hydrocarbon feed can be injected along the entire length of the lower part of the upstream reactor, and of course different injection points can be selected for both fresh and recycled streams. For this purpose, the lower part of the upstream reactor can be up to 80% of the total length of the upstream reactor in order to achieve an extremely short contact time, which influences the optimum conversion of the hydrocarbon feed. If a dense catalyst bed is used, it is also possible to work with devices for direct feeding of catalyst particles and / or hydrocarbon feed directly into the dense bed zone.

The foregoing conditions are adapted to prepare fuels for spark-ignition internal combustion engines, but the process can also be adapted to maximize the production of heavy hydrocarbon products such as jet fuel, diesel oil, fuel oil and various chemicals, especially olefins and aromatics.

In the catalytic process, some of the non-volatile carbonaceous materials or coke deposit on the catalyst particles. By coke is meant highly condensed aromatic hydrocarbons, usually containing less hydrogen, for example about 4 to 10% by weight. If the hydrocarbon feed contains sulfur in the form of organic sulfur compounds, the sulfur is also present in the coke. As the amount of carbonaceous deposits on the catalyst increases, the catalyst cracking activity decreases as well as the selectivity of the catalyst in the preparation of gasoline blends. The catalyst particles can be regenerated again by removing major portions of coke from the catalyst surface using a suitable regeneration process.

The spent catalyst from the oil conversion reactor is stripped of expelled matter before it is admitted to the recovery plant. The stripping device used in conjunction with a moving bed cracker can most effectively operate at the same temperature as that maintained in the conversion reactor, i.e., at a temperature of about 454 to about 649 ° C, and preferably at a temperature above 466 ° C. Steam is preferably used as the ejection gas, although steam-containing nitrogen or some other inert gas containing steam, optionally waste gas or flue gas may be used. The purging gas is preferably used at an overpressure of generally 60 to 200 psig, which is suitable for substantially complete removal of the ejectable compounds from the worn catalyst.

The process of the present invention can be used in any process, both, or a catalytic cracking recovery system, but is preferably used in a recovery system comprising at least one dense bed zone and one with a dilute phase. Worn catalyst particles after performed. The ejection of the expellable fractions may be conducted by a suitable conduit from the ejection device to the dense bed section of the regeneration device. The entry may be bottom or side, and desirably near the upper end of the dense bed moving zone. The inlet may also be directed to the upper end of the regeneration device, where the catalyst is first contacted with substantially consumed regeneration gas in a limited zone of the diluted phase.

Catalyst regeneration is achieved by firing coke deposits from the catalyst surfaces by treatment with a molecular oxygen-containing gas such as air. A number of regeneration processes are performed to achieve a remarkable regeneration of catalyst activity as a function of coke removal rate. With the progressive removal of coke from the catalyst, it is becoming increasingly difficult to remove the remaining coke, and in practice, an intermediate stage of acceptable catalyst activity that can be achieved is chosen as an economic compromise.

Large amounts of oxygen or air are required to burn coke deposits on the catalyst. Coke oxidation can be regarded in a simplified form as carbon oxidation, and this can be explained by the following chemical equations, but they do not imply any limitation: a) C + O2 -> CO2 bj 2 C + O2 -> 2 CO cj 2 CO + O2 -> 2 CO2

Reactions aj and b) proceed in both cases under typical catalyst regeneration conditions, where the catalyst temperature can be about 566 to about 788 ° C, and examples are known for the chemical alternating effects of gas on a solid occurring when the catalyst is regenerated at this temperature. range. The effect of the elevated temperature translates into an increased rate of carbon combustion and improved separation of carbon or coke from the catalyst particles. Since the increased combustion rate is accompanied by a greater amount of released heat, reaction c) in the gas phase can take place in the presence of sufficient free or molecular oxygen. This latter reaction is induced and initiated by free radicals and can be further led and catalyzed.

The combustion of sulfur-containing coke deposits on the catalyst also leads to the formation of sulfur oxides, which can be expressed by the following chemical equations, which, however, do not imply any limitation in any way:

dj S (in coke + O2 - »SO2

e) SO2-1 / 2O2 SO3

Reactions d) and e) also take place under typical cracking catalyst regeneration conditions, but while reaction dj proceeds rapidly, the reaction ej is relatively slow. However, the reaction ej can be catalyzed by the same catalysts that catalyze the previous reaction cj. Molecular sieves absorb sulfur oxides and therefore the reaction may be carried out on the catalyst in the solid particles of the present invention. Other proportions of solid particles can also absorb sulfur oxides. The resulting sulfur trioxide can then react with a suitable metal or in particular with a metal oxide in the metal reagent to form a stable metal sulfate in the solid particles. When the solid particles are separated from the gases discharged from the regeneration zone, the metal sulfate in the solid particles is returned to the reaction zone. Thus, sulfur leakage in the form of gaseous sulfur oxides in the waste gases from the recovery zone cannot occur.

The sulphate remains on the solid particles, which are returned to the cracking zone, where the prevailing reducing atmosphere reduces the sulphate to the sulphide of the metal, corresponding to the metal of the metal reagent, and possibly also to hydrogen sulphide. Upon ejection with a suitable vapor-containing gas, sulfur in the stripping zone is converted into hydrogen sulphide, which enters the waste gases from the stripping zone. The metal reagent is regenerated in this manner and is again suitably adapted to react with the sulfur oxides in the further passage through the regeneration zone. The hydrogen sulfide can then be recovered from the stripping zone together with the cracking products, whereupon the hydrogen sulfide is converted to elemental sulfur by conventional means.

These reactions can be summarized as follows, but are not intended to be limiting:

Regeneration equipment:

M _x 0 + SO 2 d - 1/2 O2 - M _x 0 + SO 3 -> M _x SO 4 reactor

M _x S0d + 4H2-M _X S + 4H2O-M _x 0 + HzS + 3H2O stripping device

M _X S + H 2 O - M _x 0 + H 2 S

All these reactions are carried out by a molecular sieve cracking catalyst and by the presence of a metal reagent according to the invention. The high cracking efficiency, which is typically characterized by molecular sieve catalysts, is substantially unaffected by the presence of a metal reagent, so that the expected feed conversion as well as the expected yield of cracking products along with reduced carbon monoxide and sulfur oxides emissions occur.

The metal reagent can be used in fine form, as a powder, separately from the molecular sieve cracking catalyst or any other carrier. In such a case, the metal reagent is used in powder form, introduced separately into the catalytic cracking cycle and mixed with the molecular sieve cracking catalyst in situ during the catalytic cracking cycle, but not before the molecular sieve cracking catalyst has been introduced into the cracking cycle. Generally, such a powdered metal agent is advantageous because the powdered substance is easy to add and set in motion in a movable catalytic cracking system. The particle size of the powdered product should therefore be selected such that further particle separation into smaller particles at the rate of particle introduction is excluded. Advantageously, the particles of such a powdered product are not very small, so that they do not excessively escape with the bed gases in the form of co-pulverized powdered material. However, cyclones, filters, separators and separators or similar devices are used to obtain the largest proportion of entrained fine materials and to avoid loss of operation. The powdered product should be strong enough to avoid excessive abrasion and to prevent further breakdown of the particles. Often, the mean particle diameter of the powdered metal reagent is 0.5 to 1 to 100 microns, preferably about 50 microns. It has been found that microparticles, i.e. particles with a mean size below about 1 micrometer, for example 0.01 to 0.5 micrometer, tend to agglomerate to form larger particle sizes which can be favorably utilized in the process of the invention. Examples of powdered metal reagents which can be used in the process of the present invention are magnesium oxide and calcium oxide, dolomite and Trimex, a product described in U.S. Pat. 3,630,696.

Alternatively, the metal reagent may be added on a suitable carrier other than a molecular sieve cracking catalyst, the metal reagent being deposited on the carrier outside the cracking cycle and then added together with the carrier to the cracking cycle where it forms part of the solid particles. The carrier can be an amorphous cracking catalyst or a solid which is substantially inert under cracking conditions, for example of ceramic nature. In such a case, the supported metal reagent is mixed with the molecular sieve-type cracking catalyst during the catalytic cracking cycle, but not before the molecular sieve-type cracking catalyst is introduced into the cracking cycle. It is suitable to use a porous support which often has a surface including pores on the surface of at least 10 and preferably at least 50 m ² / g. Examples of such carriers include silica, alumina, a mixture of silica and alumina. The metal reagent may be applied to such a substrate by ion exchange, impregnation or any other means, for example by contacting the substrate or one of its components 3 with a solution or solutions of a metal compound or metal compound metal compounds in an amount suitable to achieve the desired metal reagent concentration. invention. The metal reagent may be combined with the support either at some stage in the preparation of the support or after preparation of the support. One way is to incorporate it into the substrate by ion exchange. Also useful is a method of ion exchange of solids or clays containing silicic acid or silicon using solutions or solutions of a compound or compounds of a metal element or metal elements of a metal reagent. Suitable compounds for this purpose include metal halides, preferably chlorides, nitrates, amine halides, oxides, sulfates, phosphates and other inorganic salts when they are soluble in water. Salts of metals and carboxylic acids having 1 to 5 carbon atoms as well as alcoholates are also suitable.

Further, for variation, the metal reagent can be applied to the molecular sieve-type cracking catalyst, or to a portion of the catalyst, to solid particles in the process of the invention, and thus the metal reagent is introduced into the cracking cycle, but not before the molecular-type cracking catalyst is added. sieves into the catalytic cracking cycle. In such a case, the metal reagent is deposited on the cracking catalyst during the cracking cycle, and the deposition method must be carefully chosen so that neither the cracking efficiency nor the selectivity of the cracking catalyst is adversely affected.

In all of the foregoing, the manner in which the metal or metals of the metal reagent is bonded to a molecular sieve cracking catalyst, to an amorphous cracking catalyst or to a substantially inert support substrate is not known precisely. The metals are complicated to combine with the carrier material and other solid particle components of the present invention. It is therefore understood that the use of the terms "metal reagent" and "introduced or incorporated" into a substrate includes metals as components which are found on the carrier material in combined or bonded form and / or in an elementary state.

The substrate may be impregnated in any manner that does not disrupt the substrate structure. The metal reagent can be impregnated with a molecular sieve-type cracking catalyst only during the cracking cycle, or an inert carrier or amorphous cracking catalyst, if inert under cracking conditions, can be impregnated only during or outside the cracking cycle. Impregnation differs from ion exchange to the extent that impregnation causes greater deposition and primary physical bonding to the surface area of the substrate, while ion exchange results in primary chemical bonding, more diffusion and hence less deposition on the surface area. During impregnation, the metal is deposited and there is no substantial ion exchange between the metal and the substrate. When impregnating the substrate, the metal or metals of the metal reagent may be used in the form of at least one salt, dissolved or dispersed in water or in an organic solvent, in an amount sufficient to apply sufficient metal or metals to the substrate. contact with solution or dispersion. After impregnation, the material can be freed from the solvent by drying, leaving the metal reagent deposited on the substrate.

Preferably, water-soluble nitric acid salt solutions are used in the impregnation, since the thermal decomposition residue of the nitric acid salt is relatively harmless with respect to the cracking catalyst efficiency. Metal halides and sulphates may also be used for impregnation, but since by-products formed in the thermal decomposition of these salts may be detrimental to the hydrocarbon cracking efficiency of the catalyst, these salts are most often used when a metal reagent is applied. to substrates which are substantially inert in the cracking reaction and which do not adversely affect the cracking of the hydrocarbons.

Another method of physically applying a metal reagent to a substrate, particularly of a porous nature, such as crystalline aluminum silicates, is to adsorb the liquid containing the degradable compound or degradable compounds of the metal or metals corresponding to the metal reagent to the substrate, followed by thermal or chemical decomposition of the compound; compounds. The substrate may be activated by heating to remove any adsorbed water by contacting a solution of the degradable metal compound (s) or metal reagent (s) and adsorbing the compound (s) onto the substrate. Typical examples of such compounds include metal alkyl derivatives, volatile metal halides and the like. The adsorbed compound (s) can then be thermally or chemically reduced to form the active state, leaving the metal reagent dispersed uniformly on the support. The thermal decomposition can be carried out, for example, in a regeneration plant during the regeneration process.

However, it is also advantageous to introduce the compound or compounds of the metal or metals contained in the metal reagent into the cracking process cycle, thereby introducing them in situ onto the substrate. Such compound (s) can be applied in a water or oil soluble or dispersible form, further in a solid, liquid or gaseous state at any stage of the cracking process cycle, so as to achieve broad solid particle distribution. For example, the compound (s) may be mixed with either the hydrocarbon feed or the gas used in the reaction zone swirl, the regeneration gas, the burner oil or the water in the reaction zone, or the stripping gas in the stripping zone, or said compounds may be added as a separate stream. Suitable compounds for in-line cycling include metal salts, and include metal diketone and metal salts of C 1 -C 20 carboxylic acids. A special example is magnesium acetylacetonate.

Preferred embodiments of the method of the invention include the working methods together with the regeneration system disclosed in U.S. Patent 3,909,392. The process is fully incorporated into the present disclosure. It is directed to an improved catalytic cracking process, including an improved catalyst regeneration process for the catalytic conversion of hydrocarbon feeds in a moving bed, wherein the catalyst is deactivated by deposition of coke on the catalyst surfaces. In this way, the coke content of the regenerated catalyst on the substrate can be extremely reduced, while at the same time maintaining a favorable thermal equilibrium in the conversion apparatus and obtaining a waste gas with an extremely low carbon monoxide content. The heat released by the combustion of carbon monoxide is absorbed by the solid particles and generated

2J part of the heat that is needed in the hydrocarbon conversion zone. According to one embodiment of the process of the present invention, the combustion of carbon monoxide to carbon dioxide is effected substantially perfectly in the recovery plant in a relatively dilute secondary catalyst regeneration zone, preferably at a temperature of 649-816 ° C, in particular at a temperature of 652-788 °. C. The temperature in the secondary stripes can be about 28-56 ^C Celsius higher than the temperature of the first regeneration zone. The partially regenerated catalyst from the relatively dense primary regeneration zone of the catalyst may be passed at an increased rate through the secondary zone in an amount and at a rate sufficient to absorb substantially all of the heat that is released in the second zone. Although the largest portion of coke from the catalyst is fired in the first zone, yet another portion of coke from the partially regenerated catalyst is fired as it passes through the secondary zone, and a catalyst suitable for recycling to the hydrocarbon conversion stage can be obtained.

According to a second embodiment of U.S. Pat. No. 3,909,392, combustion is substantially complete, including both oxidation of coke or carbon on the catalyst and oxidation of carbon monoxide, in a single, relatively dense catalyst regeneration zone due to favorable control and mainly control of regeneration temperature and gas speed.

In the same manner, in carrying out the process of the present invention according to the embodiments with respect to the recovery system of U.S. Patent No. 3,509,392, the major amount of heat released by combustion of carbon monoxide in the recovery zone is absorbed on solid particles of the invention that include a cracking catalyst. , thereby providing some of the heat required for the cracking zone. Advantageously, such embodiments of the process of the present invention allow substantial combustion of coke and carbon monoxide in the dense phase zone when such a zone is used, where a significantly larger proportion of solid particles is present compared to the dilute phase zone used, so that the heat generated scattered. As the proportion of combustion in the dense phase increases, the heat evolution in the dilute phase zone decreases substantially, thereby reducing or eliminating the need for rapid movement of solid particles in the dilute phase zone, which would be necessary to absorb the heat generated.

In such embodiments, the method comprises the use of solid particles of the present invention comprising a molecular sieve cracking catalyst and a metal reagent of the invention in a system wherein substantially the carbon monoxide is substantially burned. The low coke content which can be achieved in this way is in the range below 0.2%, preferably below about 0.05%. The process can lead to waste gases with a carbon monoxide content of less than 0.2% by volume, for example with a content of 500 to 1000 ppm, as well as to as low a content as 0 to 500 ppm. The method also relates to the provision of a device for recovering the released heat by direct transfer to solid particles within the regeneration device.

In such embodiments, the gas causing movement or swirling in the dense zone of the regeneration device may have a velocity of, for example, about 0.06 to about 1.22 m / s, in particular about 0.15 to 0.19 m / s.

The regeneration gas used to move the particles in the dense bed contains free or molecular oxygen, and the oxygen is fed to the regeneration device preferably in an amount that is somewhat higher than the amount required to completely burn the coke, i.e. carbon and hydrogen to form carbon dioxide and steam. The amount of excess oxygen compared to the amount required to completely burn the coke is about 0.1 to about 25% or more of the theoretically necessary stoichiometric amount of oxygen, but preferably is at most 10%. For example, when air is used as a regeneration gas, a 10% excess of air results in a volume excess of 2% oxygen in the exhaust gas stream consumed. Preferably, the concentration of molecular or free oxygen and carbon monoxide is kept at any point in the recovery plant outside the explosive limit under the conditions, and preferably the concentration of carbon monoxide is below the explosive range under the reaction conditions used to eliminate any danger and risk of explosion.

The regeneration gas may contain, in addition to the free or molecular oxygen, an inert gas or diluent gas such as nitrogen, steam, etc., recycle gas from the waste stream from the regeneration plant and the like. Often, the oxygen concentration of the regeneration gas in the inlet portion of the regeneration device is about 2 to 30% by volume, preferably about 5 to 25%. Since air is usually used as the oxygen source, the major part of the inert gas may be nitrogen. The inert gas can be used to distribute the excess heat from the coke combustion on the catalyst. The gaseous effluent from the recovery plant is a source of hot inert gas and part of the gas may be returned to the recovery plant, for example, along with a sufficient amount of oxygen or air containing gas or, possibly, substantially pure oxygen to supply the desired oxygen concentration. Thus, the recycle gas can be used in direct heat exchange to increase the temperature of the regeneration gases to achieve even greater utilization of heat in the system.

The solid particles in the diluted phase may be partially carried away into the separation zone, which typically consists of cyclone separators in several stages, and from there the solid particles are guided, directly by submerged lines, into the dense bed zone; the spent gas from the regeneration and combustion zones is collected in a collecting device from which it is subsequently discharged taking into account the recovery of the contained heat. Waste gas recovery methods include steam generation, ejection of expelled fractions from the catalyst after its use, indirect heat exchange with various refinery streams, such as feeds to special conversion processes, and use for various equipment for drying or evaporation.

1 and 2 are front views, partly in cross-section of a device suitable for regenerating a catalyst according to embodiments of the process of the invention, including regeneration schemes of U.S. Pat. No. 3,909,392. Existing oil and hydrocarbon cracking equipment, especially in moving bed catalytic cracking, which includes a number of sub-equipment and arrangements for cracking, ejection and recovery.

Figure 1 shows one possible embodiment of the process according to the invention, wherein the worn-out catalyst for the expulsion of the expelled fractions, fed from the reactor (not shown), is fed to the regenerator bottom. The solid particles containing the catalyst impregnated with a metal reagent from the stripping zone together with the catalyst are passed from the reactor to the bottom of the recovery plant. The solid particles flow up through the inlet ducts 2 and 3 and are deposited via the discharge head 4 and 5 in the dense bed of the lower part 6 of the regeneration device, which portion extends up to the boundary area between phases 7. The solid particles in the dense phase bed They are set in motion or swirled by a stream of combustion air supplied via a duct 8 with a closure 9 and a further duct 10 to the air ring 11. A substantially uniform air flow through the regeneration zone can be achieved by using additional air rings not plotted, . Air coke combustion on a worn catalyst is initiated in a dense bed. Higher temperatures can be achieved by temporarily or occasionally burning a stream of torbanite oil, such as decanted bed oil. The torbanite oil can be fed through a line 12 with a cap 13 and a further conduit 14 that opens through a nozzle at a level above the air ring 11. A portion of the solid particles 24 continuously moves upward into the dilute phase zone including the upper part 13 of the recovery device. The coke combustion continues in the dilute phase zone, and the combustion gas, largely spent, is discharged together with the entrained solids to the first stage of the cyclone separators 20 and 21. The largest portion of the solids is it separates in the first cyclone stage and passes through the submerged lines 22 and 23 back to the dense phase zone. The gases and remaining solid particles are passed through cycles 24 and 25 between the cyclones to the second stage of the cyclone separators 26 and 27, where substantially all of the remaining solid particles are separated and passed through the submerged lines 28 and 23 to the dense phase bed. The substantially spent combustion gas is then discharged via lines 20 and 31 into the receiver 32 and then discharged from the recovery plant via line 33. This waste gas stream can be utilized in an appropriate manner to provide heat exchange without depiction using a refinery stream or to produce process steam. The solid particles containing the regenerated dense bed catalyst with tubes 34 and 35 equipped with collecting heads 34 and 35 are returned to the cracking reactor.

Although the combustion air supply usually leads to an excess of oxygen compared to the amount required to completely burn the coke from the catalyst particles to form steam and carbon dioxide, the combustion of the coke in a dense phase bed according to one embodiment of the invention using U.S. Pat. No. 3,909,392, completely. In this embodiment, the combustion gases rising up from the dense phase bed contain a substantial amount of carbon monoxide as well as carbon dioxide and oxygen. The coke remaining on the catalyst, as well as the carbon monoxide, is essentially burnt perfectly in the dilute phase zone with great heat evolution. When the carbon monoxide is burned in the diluted phase, the high temperature zone typically occupies a large portion of the dilute draft zone, and in particular is at the X-marked location, which can easily be seen by the unhindered window in this horizontal plane. The increase in the regeneration temperature within the dilute zone is partly due to the absorption of heat by the mass of solid particles carried either upwardly by the flow of combustion gases or escaping from the dense bed through the duct head 40, and from there the particulate fountain is divided into the dilute phase zone. The solid particles can be drawn off by air, steam or other inert gas, which is led through line 42 with a shutter 43 with a further line 44, which opens at a short distance from the lower ¹ end of line 40. Excessive temperatures of the upper part of the recovery can be controlled and controlled , for example, by conduits 45 and 46 with a closure 47 using another conduit 48 and a steam discharge device 49. Temperatures near the gas collector 32 can also be controlled by supplying steam using conduit 50, shutter 51 and conduit 52 to a steam ring 53 that extends around the conduit 32. Optionally, additional undisturbed spray water cooling can be installed, which is preferably controlled per section lines 24 and 25 between cyclones. Such lower temperatures favorably affect the formation of stable metal and sulfur containing compounds in the regeneration zone.

Figure 2 is an example of another embodiment of the process of the present invention using the recovery system of U.S. Pat. No. 3,909,392, wherein solid particles comprising a worn stripper catalyst and a metal reagent that is fed from a cracking reactor are flanked to the recovery equipment. Solid particles containing a worn catalyst impregnated with a metal reagent are introduced into the regeneration device 101 by means of a conduit 102 which opens close to below the boundary surface 7 between the phases. The particles are directed downwardly to the recovery device to allow them to be added to the dense bed that is maintained at the bottom, i.e., the portion indicated by 106. The solid particles are moved by the combustion air stream supplied through the conduit 108 with the shutter 103 and Further lines 110 into the air ring 111 may be used. Other non-illustrated rings may be used to achieve equilibrium air distribution in the regeneration zone. As described in connection with Figure 1, combustion of coke from worn catalyst particles in the dense phase zone is initiated, whereby higher temperatures can optionally be achieved by intermittent or temporary combustion of torbanite oil in said zone. In such a case, the torbanite oil is fed via a duct 112 with a cap 113 and a duct 114 extending in the form of a nozzle.

The air velocity for moving the particles or for swirling the particles can be controlled by continuously entraining the solid particles upwardly to absorb heat in the dilute phase zone located in the upper portion 115 of the regeneration device, i.e. above the boundary surface 187 of the phases. Combustion of coke as well as combustion of carbon monoxide can take place further in the dilute phase zone, and the largely worn combustion gas is discharged, along with entrained solids, to the first stage of the cyclone separators 120 and 121. in the first cyclone stage and through the dip lines 122 and 123, these particles are fed back down into the dense phase zone.

The gases and remaining solids are passed through cycles 124 and 125 between the cyclones to the second stage of the cyclone separators.

126 and 127, where substantially all of the remaining solid particles are separated and passed downwardly into the dense bed by means of dip lines 128 and 129. Combustion gas, substantially spent, is routed via ducts 130 and 131 to the sump 132 and The solid particles containing the regenerated dense bed catalyst are drawn off through tubes 134 and 135 equipped with a header 136 and 137, and returned to the catalytic cracker.

As described in the embodiment of Figure 1, carbon monoxide is burned in the dilute phase zone to form a high temperature zone that contains a large portion of the dilute phase zone and is particularly noticeable at the location indicated by the X. The dilute phase zone is largely achieved by the absorption of heat by the mass of solid particles which are entrained and entrained by an increasing combustion-air flow. The temperatures near the sump 132, the cyclones and the connecting conduits may optionally be reduced by the steam that flows through the conduit 150 with the shutter 151 and the conduit 152 of the steam ring 15-3, which is situated around the sump 132. water spraying equipment.

According to a further and particularly preferred embodiment of the process according to the invention, the device according to FIG. 2 is used with substantial changes in the operating parameters compared to the embodiment just described. In this embodiment, the gas velocity and solids injection are adjusted such that the coke and carbon monoxide are substantially burned in the dense phase, and heat is distributed throughout the bed.

When operating in a system using one of the two embodiments just described, the heat released by substantially complete combustion of coke and carbon monoxide is recovered by absorption on the solid particles in both phases while returning the solid particles to the dense phase zone. thereby ensuring a consistently high temperature in the dense phase band. The recovered solid particles can bring in additional heat to raise the temperature of the dense phase so that it favors the combustion of other coke deposits on the catalyst particles, so that the remaining coke deposits burn off substantially perfectly. The system is operated in such a way that substantially all of the combustion takes place perfectly in the dense catalyst phase zone, then the heat is dispersed into the phase by absorption by moving solid particles, and the remaining k-shaped deposits are burnt. In this respect, in all embodiments the solid particles containing the regenerated catalyst which are fed back from the regeneration device back to the cracking device preferably comprise from about 0.01 to 0.10% by weight, preferably from 0.01 to 0.05% by weight, and in particular about 0.01 to about 0.03% of carbon or coke on the catalyst, and the particles can be used directly at a preferred temperature for introduction into the cracking reactor.

An essential advantage of the process according to the invention is that a recovered catalyst is obtained which is essentially characterized by improved activity and selectivity that is close to the fresh catalyst, especially for use under conversions taking place in very short contact times in ascending reactors. The cracking activity of the catalysts containing the molecular sieves and their selectivity in converting hydrocarbon feeds to the desired products is always strongly influenced in a favorable direction by better removal of the residual carbon or coke on the catalyst during regeneration. The low coke content of the regenerated catalyst is particularly advantageous for moving bed catalysts containing catalytically active crystalline aluminum silicates. As a result, higher yields of the desired conversion products can be achieved.

In the cracking process using the dense phase and the upper phase of the dilute phase in the regeneration zone, oxidation of carbon monoxide to carbon dioxide in the dense phase of the regeneration plant can take place to a large extent, often at least 60%, usually in the range 65-95%. . Oxidation of carbon monoxide to carbon dioxide in the dense phase generates heat to promote the steady combustion of coke deposits on the moving bed catalyst. In addition, due to the oxidation of a substantial portion of the carbon monoxide in the dense phase, the upper part of the recovery plant contains a lower carbon monoxide content for combustion, so that afterburning and high temperatures due to uncontrolled and excessive combustion of the carbon monoxide falls away. This also avoids the undesirable effect of these high temperatures on the reactor components, the gas evacuation, the collecting device for separating the reactor part, the gas evacuation, the collecting device for separating off the waste gas particles, such as cyclones, influence the activity of the catalyst.

Solid particles containing regenerated catalyst particles having an unusually low coke residue are thus obtained from the dense phase, and are essentially contacted with a fresh hydrocarbon feed or a mixture of such feed with hydrocarbon fractions via a line to the cracking reactor via a dense phase bed. that go back. Since the oxidation of carbon monoxide resulting from the combustion of coke deposits on the catalyst is predominantly in the dense phase, and in the preferred embodiment substantially completely dense, the regenerated catalyst can be fed to the cracking reactor at a substantially higher temperature as well as higher. activity than previously possible using conventional procedures.

The main advantage of the process according to the invention is in the unusually low content of carbon monoxide in the waste gases from the recovery plant. While the waste gas from conventional cracking catalyst regeneration usually contains about 6-10% carbon monoxide, similar amounts of carbon dioxide and very low oxygen, the carbon monoxide content of the off-gas using the present catalyst regeneration can be very low in the process of the present invention. below about 0.2% by volume, for example in the range of 500 to 1000 ppm, based on gas volume. Preferably, the content is even lower, for example in the range of 0 to 500 ppm. Such a low concentration of carbon monoxide in the off-gas or flue gas allows direct discharge of the off-gas into the ambient atmosphere, since the gas complies with standard air purity requirements. If desired, the remaining carbon monoxide can be appropriately burned in the exhaust from the recovery plant. As a result of this advantage of the method according to the invention, the investment costs that would otherwise be required to install existing carbon monoxide burners as well as other turbine-type or other partial energy recovery burners which are released by additional oxidation of the oxide carbon monoxide in such a way that the conditions with regard to the degradation of air quality by carbon monoxide are respected.

The process according to the invention has further advantages. These relate to the problem of post-combustion and thermal equilibrium. The main problem that arises in practice, especially in the regeneration of movable bed catalysts and which has to be overcome, is the so-called post-combustion, see for example Hengstebeck "Petroleum Processing", Mc Graw-Hill Co., 1959, pp. 160 and 175 , and a discussion in the "Oil and Gas Journal", 53, 93-94 (1959). The term refers to the afterburning of carbon monoxide to form carbon dioxide according to equation c) above, and this course is extremely exothermic. Post-combustion is extremely undesirable in catalyst regeneration processes because it is associated with very high temperatures, which can damage the equipment, and can permanently deactivate the cracking catalyst particles. Numerous precautions for regenerating the movable catalysts result in post-combustion, which is a serious circumstance in technology, and a number of measures have been described to control the regeneration process so that post-combustion is eliminated. In the last 222221, it has been attempted to increase the regeneration temperature for a variety of reasons, and very carefully elaborated devices have been described with which the regeneration temperatures can be maintained using suitable devices to control the oxygen supply to the reactor in the region of incipient post-combustion. U.S. Pat. Nos. 3,161,583, 3,206,393 and 3,513,087. According to current practice in non-post-combustion processes, the off-gas from regeneration plants typically contains low oxygen and a significant amount of both carbon monoxide and carbon dioxide approximately equimolar amounts.

Further combustion of carbon monoxide to carbon dioxide is an interesting source of thermal energy, since reaction c) is strongly exothermic. The post-combustion may take place at temperatures above about 595 ^° C, releasing about 10,674.4 kJ / kg of oxidized carbon monoxide. This typically represents about a quarter of the total amount of heat released, that is, the heat that is released when the coke is completely burned. The combustion of carbon monoxide may be carried out ^one in a controlled manner in a separate boiler for combustion of carbon monoxide, after separation of the catalyst from the stream of waste gas as described for example in U.S. Patent

753 925. The amount of heat released can be utilized for numerous refining processes, for producing high pressure steam, etc. Other uses of this thermal energy are described in U.S. Pat.

012 962 and 3,137,133 (turbine propulsion) and U.S. Pat. No. 3,363,993 (oil feed preheating) These heat recovery processes are used to prevent the release of carbon monoxide as a proportion of the off-gases in the atmosphere and make it very difficult Procedures require their own and sophisticated equipment.

On the other hand, silica-based and alumina-based catalysts, which are commonly used for many years in numerous cracking processes for petroleum hydrocarbons, are not very sensitive to the residual coke content on the catalyst, provided the coke content does not increase by weight above about 0, 5%. However, silica-based and alumina-based catalysts have been largely displaced by other catalysts which additionally contain a crystalline component of aluminum silicate and are known as zeolites or molecular sieves. Catalysts containing molecular sieves are substantially more sensitive to residual coke and are strongly influenced both in terms of catalytic activity and catalyst selectivity when converting feed to the desired product or products. Due to the difficulties of conventional catalyst regeneration technology with respect to the removal of the last remaining carbon deposits, the coke content generally corresponds to the residual coke content of the regenerated catalyst in the range of about 0.2 to about 0.3% by weight.

Since increased activity and selectivity has been achieved using lower molecular coke cracking catalysts, there is a strong incentive to seek means to further reduce the remaining coke content. It is highly desirable to have a coke content below about 0.03% by weight, but such a low content cannot be achieved by conventional techniques and equipment. Measures taking into account larger regeneration plants, higher catalyst content, higher heat losses and the like are far from being sufficient to develop similar catalysts with ideal activity.

Numerous moving bed cracking devices operate on the principle of "thermal equilibrium", which is dependent on the combustion of coke to obtain the heat required for the process itself. However, it has not yet been possible to utilize the advantages of cracking catalysts, especially zeolite catalysts, which can be achieved especially in an ascending reactor, where the contact times between the catalyst and the oil vapors are extremely low. An operating process that leads to high conversion, including high selectivity, has a favorable effect on the low catalyst to oil ratio in the upstream reactor, and this results in less heat that can be achieved by burning that amount of coke available in the recovery plant. . For this reason, an external heat source, such as a hydrocarbon feed preheater, is often required in order to raise the temperature of the catalyst, or else the entire plant can be maintained at a lower fresh feed temperature. Such undesirable features can be eliminated by the method of the invention or reduced to a minimum so as to allow efficient recovery of additional solid heat for transfer to the upstream reactor. The heat obtained in the combustion of coke in the usual working methods corresponds to 35 520 kj / kg and in the process according to the invention at least 37 200 kj / kg. These higher combustion heats lead to an increase in the temperature in the recovery plant, a reduction in the coke content of the regenerated catalyst, and a decrease in the circulating velocity of the solid particles, with better yields at a given conversion stage.

Example 1 g of a solution consisting of 6.9 g of a lubricating oil additive containing by weight

9.2% magnesium in the form of magnesium hydroxide, magnesium carbonate and magnesium salt of polypropylbenzenesulfonic acid, in

33.1 g of catalytic light cyclic oil (which is always the middle distillate obtained by catalytic cracking at boiling point)

221 to 343 [deg.] C.), is cracked in a moving bed or fluidized bed cracking experimental apparatus with a fixed amount of a cracking catalyst consisting of a cracking catalyst mass, crystalline aluminosilicate and a matrix containing 2.5% by weight molecular sieves and 0.6% sodium; withdrawn from a conventional catalytic cracking apparatus using a moving bed and then calcined. The recycled oil was cracked at 371 ° C for 4 minutes. After purging the catalyst bed with nitrogen at 677 ° C for 10 minutes, the catalyst bed is cooled to 371 ° C and the cracking, purging and regeneration cycle is repeated until the magnesium, zinc and phosphorus recovered in the catalyst process drop to 1100, 703 , or 59 ppmi. Zinc and phosphorus are inseparably present.

Example 2

The procedure of Example 1 is repeated, but the cracking, rinsing and regeneration cycle is carried out using 10 g of solution

6.5 g oil and 3.5 g lubricating oil additive containing 1.6% zinc, 1.3% phosphorus and 4.6% magnesium until the magnesium, zinc and phosphorus content of the catalyst falls to 2400, 1200, or 1097 ppm.

Example 3

The procedure of Example 2 is repeated, but using a conventional equilibrium cracking catalyst with a 3.3 wt% molecular sieve content in a silica-alumina matrix, also withdrawn from a conventional mobile catalytic cracker, calcining the catalyst, and then a cracking, purging and regeneration cycle is carried out until the magnesium, zinc and phosphorus content of the catalyst drops to 4600, 340, or 1136 ppm, respectively.

Examples 4 to 8

The laboratory experimental recovery plant will be used to determine the effectiveness of a certain number of impregnated catalysts in achieving reduced sulfur dioxide emissions in the off-gases from the recovery zone. A synthetic waste or flue gas containing 1500 ppm of sulfur dioxide in a mixture of 4% by volume of both oxygen and water vapor in nitrogen is passed through the moving bed or fluidized bed of the cracking catalyst of the molecular sieve type, and the cracking catalyst is impregnated with metal and stored in a glass recovery plant equipped with heating to achieve a desired recovery temperature of 677 ° C. The catalyst temperature is measured with a thermocouple. A cyclone is used to separate the entrained catalyst from the gas, the gas being discharged from the recovery plant, passing the catalyst back to the catalyst bed. The operating time of the regeneration device is about 40 to 90 minutes under the given conditions, since there is sufficient time to achieve the metal oxidation degree on the catalyst in an efficient moving-catalytic cracker.

The sulfur dioxide content of the gases from the recovery plant is analyzed continuously using an ultraviolet analysis device. The amount of sulfur dioxide removed in the recovery plant is determined as the difference between the content of sulfur dioxide in the fresh synthetic mixture and the content in the gases from the recovery plant. The volume percentages of sulfur dioxide removed from the recovery gas from the regeneration zone are a function of the time elapsed since the start of the experiment, and are found in Table 1. The percentages of sulfur dioxide removed are at the time of saturation of the catalyst and its surface area.

Example 4 is a comparative example where synthetic waste gas is used with a flow rate of 1084 ml per minute and an impregnated, equilibrium catalyst of Examples 1 and 2. Examples 5 and 6 were performed using the impregnated catalysts prepared in Experiments 1 and 2, and utilization of the flow rate of the synthetic gaseous waste mixture 989 or 1014 ml per minute. Example 7 is a comparative example using the impregnated catalyst of Example 3 'at a synthetic exhaust gas flow rate of 891 mL per minute. In Example 8, the impregnated catalyst prepared in Example 3 was used at a flow rate of 992 ml of synthetic gas mixture per minute. Flow rates are measured at 15.6 ° C.

Example

Time

TABLE 1

% By volume of SO 2 removed 4 5 6 7 8

0—10 78—63 85—82 92—91 36—24 60—49 10—20 63—43 82—78 91—89 24—16 49—39 20—30 43—32 78—74 89—88 16—14 39—33 30—40 32—27 74—70 88—87 14—13 33—30

Examples 9 and 10

In Example 9, the procedure of Examples 4 to 8 is repeated, but a synthetic waste gas containing 4% by volume of carbon monoxide, oxygen and water vapor in nitrogen at 1000 ml / min (measured at 15.8 ° C) is used. The gas is passed through a moving bed or fluidized bed of a mixture of powdered magnesium oxide of a particle size of not more than 5 micrometers and an impregnated, calcined, equilibrium cracking catalyst of the molecular sieve type currently available ¹ , containing 5,3% by weight of hydrogen and rare earths, Ion exchange, crystalline "Y" type silicate, and a mixture of silica and alumina containing 30% by weight of alumina instead of impregnated catalyst, containing 0.3% by weight of magnesium oxide and about 70% by volume of carbon monoxide to be converted to oxygen. In Example 10, the non-impregnated catalyst of Example 9 was used in the absence of magnesium oxide under otherwise identical conditions, thereby converting 58% by volume of carbon monoxide to carbon dioxide.

Examples 11 and 12

In Example 11, a gas oil with a sulfur content of 1.67% by weight is cracked in a conventional moving bed cracker under catalysis in an ascending reactor. Conventional regeneration gas is used, and a fixed amount of a molecular sieve-type cracking catalyst consisting of a cracking catalyst mass, crystalline aluminosilicate and a matrix containing 2.5% by weight molecular sieves and about 0.6% sodium is used. In Example 12, a second injection of gas oil with a sulfur content of 1.60% by weight in the same cracker is cracked using the same regeneration system and the same cracking catalyst but additionally impregnated with magnesium and zinc. These metals are deposited on the catalyst using a small amount of magnesium sulfonate and zinc dialkyldithiophosphoric acid, in the form of a lubricating oil addition to the feed. A few hours after such addition, 0.3% magnesium and 0.1% zinc were deposited on the cracking catalyst. The operating conditions and composition of the waste gas from the regeneration zone are given in Table 2 below.

TABLE 2

Examples

Cracking Conditions Cracking Temperature ° C Total Injection Rate / Day Total Injection Rate to Fresh Injection Catalyst Circulation Rate kg / min Catalyst to Oil Weight Ratio

Stripping conditions Stripping temperature ^C C Steam / catalyst ratio kg / kg

Regeneration conditions Thick bed temperature ° C Combustion air speed g / h

Composition of waste gas from regeneration zone

CO 2, mol. %

CO, mol. %

Oz, mol. % sulfur dioxide, ppmv

524 5 866

1.07

26.4

5.3

521

4.3

688 187 048

521 5,580

1,25

23.09

5.2

518

4.7

707

221093

13.0

0 0.5

580

14.0

5.6

2,0

Example 13

A solution of 36.9 g of calcium nitrate tetrahydrate in 70 ml of water is used to impregnate 82.4 g of alpha alumina particles having a specific pore size of 0.260 cm @ ³ / g. The impregnated alumina is dried overnight at 121 ° C and then calcined for 3 hours at 538 ° C to give particles containing 7% calcium by weight.

Example 14

Prepare a solution by dissolving 450 g of magnesium nitrate hexahydrate in enough water to obtain 500 ml of the solution. To this solution was added 232 g of fluidizable alpha alumina particles which passed through a 100 mesh sieve (150 micron diameter). The excess solution is then filtered off and the impregnated aluminum oxide is dried at 121 ° C and calcined at 538 ° C. A sample of 20 g of the resulting solid was collected and the residue was added to the above filtrate, excess solution was removed by filtration, and the solid was dried at 121 ° C and calcined at 538 ° C. This procedure is repeated twice with a 20 g sample taken before each repeat to give a particulate substance containing 14.3% magnesium by weight.

Example 15

A solution of 0.116 g of barium nitrate in sufficient water to be 12 ml is used to impregnate 20 g of alpha alumina in the form of particles having a specific surface area of 1.4 m ² / g and a specific pore volume of 0.254 µm ³ / g. The impregnated alumina was dried overnight at 121 ^° C and calcined at 538 ° C for three hours to give 0.3% barium particles.

Example 16

The ability of different masses to absorb sulfur dioxide from a gas is measured in this way;

A sample of mass of 1 g is placed on a glass wool plug in a quartz sample tube with a diameter of 1.3 cm and a length of 41 cm. The tube is then placed in a tube furnace and heated to the desired temperature, and a scrubbing gas containing 2.6% by volume water vapor and helium is passed down the test bed at a rate of 10 cm ³ / min. After a 1 hour wash with the sample down, a synthetic gas containing 0.10% by volume sulfur dioxide is passed. 2.9% oxygen, 2.6% water vapor and as the remainder helium at a rate of 10 cm ³ / min. After passing through the sample bed, a gas sample is taken periodically and the sulfur dioxide content is determined by gas chromatography.

Results for CBZ-1 cracking catalyst particles (from Davison Chemical Division, W. R. Grace &

29.1% alumina, 0.46% sodium oxide and 0.11% iron and zeolite Y are shown in Table 3i as Test A. Results for a CBZ-1 crack catalyst mixture with 1% by weight additive particles prepared according to the method of Examples 13 and 14 are shown in Table 3 as Test B and C. Finally, the results for the pure additive prepared according to Example 15 are shown in Table 3 as Test D. The samples used for Test A, B and C were steam treated at temperature 760 ° C (100% atmospheric vapor) 5 hours before use.

Example 17

A 1.67 percent sulfur gas oil is cracked in the same process unit using the same crack catalyst and under the same conditions as described in Example 11. However, fluidizable additive particles containing 15 wt% magnesium on amorphous the silica and alumina supports by adding to the regenerator a sufficient amount of the cracking catalyst / additive mixture to contain 0.5% by weight of magnesium. A small amount of additive is then added to the periodococci to maintain the magnesium concentration to 0.5% by weight in the mixture of solids that circulate through the cracking unit. Analysis of the gas discharged from the regeneration zone revealed a sulfur oxide content of less than 50% of the amount produced in the process of Example 11 when the magnesium additive was not used.

TABLE 3

Exam

A B C D

Crack catalyst CBZ-1 CBZ-1 CBZ-1 -. Additive according to example - 13 14 15 Dec Ingredient composition - Ca / AGO, Mg Al. (B Ba / Al ₂ O _; Additive weight ratio to the cracking catalyst - 1: 99 1: 99 - Temperature, ° C 677 677 677 749 Percentage of oxide by volume of sulfur dioxide in gas after 5 min. 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 10 min. 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 20 min. 53 50 100 ALIGN! 100 ALIGN! 40 min. 2? 36 100 ALIGN! 100 ALIGN! 60 min. 14 23 about 100 52 80 min. 9? 28 96 min 85 24

Claims (7)

CLAIMS 1. A process for cyclic fluidized catalytic cracking or catalytic cracking in a fluidized or in an animal phase of hydrocarbon materials having a sulfur content of 0.2 to 6% by weight, in which the feed is cracked in a reaction zone with fluidized or optionally solid particles. molecular sieve cracking catalyst, catalyst particles deactivated by sulfur and carbonaceous deposits are separated from the reaction zone product and introduced into a stripping zone where the volatile deposits from the deactivated catalyst are stripped off with a stripping gas, stripped catalyst particles are separated from the stripping zone product; they are transferred to the regeneration zone and by combustion of the non-stripped deposits containing sulfur and carbon with the gas containing them, the oxygen is regenerated and the regenerated catalyst particles are separated = from the gas from the regeneration zone and returned o A reaction zone, characterized in that the solid particles containing the molecular sieve-type cracking catalyst are allowed to run along with the metal reactant, the metal reactant being at least one metal in free form or in the form of a magnesium, calcium, strontium and barium, wherein the amount of the metal reactant is sufficient to absorb at least 50% of the sulfur oxides that develop during the combustion of the sulfur and carbonaceous deposits in the regeneration zone and wherein the metal reactant is introduced into the cracking cycle in liquid or solid particulate form from the cracking catalyst of the molecular sieve type, the feed is cracked in the presence of circulating particles at a temperature of 454 to 649 ° C, the volatile products separated from the circulating particles are stripped at a temperature of 454 to 649 ° C with a stripping gas containing finding steam at a steam to crack catalyst weight ratio of 0.0005 to 0.025 per unit of time, sulfur and carbon-containing deposits are burned from the stripped circulating particles at a temperature of 566-788 ° C, the circulating particles absorb at least 50% of sulfur oxides The sulfur-containing carbon and carbon in the regeneration zone, the gas containing molecular oxygen and the traces of sulfur oxides and the absorbed sulfur oxides are removed from the regeneration zone as volatile components from the reaction and / or stripping zone. 2. A process according to claim 1, wherein the metal reagent consists of at least one metal in free form or in the form of a compound selected from magnesium and calcium. 3. A process according to claim 1, wherein the metal reagent ¹ is used in an amount of 0.1 to 0.5% by weight based on the particulate mixture. 4. A process according to claim 1, characterized in that a waste gas containing at least 0.01% by volume of molecular oxygen is removed from the regeneration zone. 5. The process of claim 1, wherein a gas containing less than about 600 ppm sulfur oxides is removed from the recovery zone. 6. The method of claim 1, wherein the metal reagent is introduced into the cracking cycle in the form of a solid particulate material comprising a supported metal reagent, the carrier being selected from amorphous cracking catalysts and solids inert to the cracking reaction. . 7. The method of claim 6 wherein the support is selected from the group consisting of silica, alumina, thorium oxides, and boron oxides.