BE849635A - CATALYTIC CRACKING PROCESS WITH REDUCED DISCHARGE OF HARMFUL GASES - Google Patents

Description

       

  Catalytic cracking process with reduced gas evolution

  
harmful.

  
The present invention relates to a cracking process

  
Fluidized bed cyclic catalytic converter, suitable for application to hydrocarbon feedstocks containing sulfur and which

  
characterized by a marked decrease in the oxide emission of

  
carbon and sulfur oxides in regeneration stack gases

  
generator.

  
A cracking catalyst which has become relatively

  
  <EMI ID = 1.1>

  
By "coke", during the craquate of the hydrocarbons in the reaction zone is continuously withdrawn from the reaction zone. This spent catalyst from the reaction zone passes to

  
a stripping zone in which carbonaceous deposits which can be removed, i.e. hydrocarbons, are removed (extracted) from the catalyst, which then passes into a regeneration zone where inactivity of the catalyst is restored by removal

  
carbonaceous deposits which cannot be removed by burning the

  
coke in an oxygen-containing gas to form carbon monoxide and carbon dioxide. The hot regenerated catalyst is then continuously returned to the reactor, to repeat the cycle.

  
In catalytic cracking, a problem arises from the incomplete combustion of carbon monoxide to carbon dioxide in the regeneration zone, leaving a significant amount of carbon monoxide in the combustion gases of the regeneration zone. Aside from the discharge of carbon monoxide

  
in the atmosphere is undesirable, carbon monoxide and residual oxygen in the combustion gases of the regeneration zone

  
tend to react and thus cause combustion in the pipes and chimneys of the installation and damage these structures by excessive temperatures.

  
In addition, when feeds with a high sulfur content, i.e. petroleum hydrocarbon fractions containing

  
organic sulfur compounds, are charged in an element

  
of the fluidized bed type catalytic cracking, the coke which settles on the catalyst contains sulfur. In the process of regeneration

  
tion of the coked catalyst, deactivated, the coke is burned from the

  
  <EMI ID = 2.1>

  
sulfur present is transformed into sulfur dioxide as well as with

  
  <EMI ID = 3.1>

  
incorporated into the flue gas stream from

  
  <EMI ID = 4.1>

  
sulfur content, sulfur oxides emissions are often in the range of about 1200 parts per million (ppm).

  
Pollution control standards have been developed for the release of carbon monoxide and particulate matter, and others are expected to be considered for other emissions, such as those sulfur oxides, in particular sulfur dioxide. Great attention is therefore paid to reducing the rate of emissions

  
various combustion products and particulate matter from the regeneration zone effluent streams associated with petroleum cracking facilities. It is necessary that the process chosen to lower these emissions be effective without reducing the activity and the selectivity of the cracking catalyst. Likewise, it is necessary that the chosen method does not replace one form of unwanted emission with another problem, for example

  
an increase in particulate emissions or operating costs. In view of these considerations, a highly desirable approach towards reducing the emission of carbon monoxide

  
and sulfur oxides in petroleum cracking plants lies in the application of a cracking catalyst which

  
is modified to minimize emissions of both carbon monoxide and sulfur oxides, while retaining the activity, stability and frictional wear resistance of the catalyst under conventional cracking conditions in either existing or new cracking facilities.

  
With regard to carbon monoxide emissions,

  
although metals are generally avoided in cracking catalysts and cracking metal-containing feeds is considered problematic, in the presence of a cracking catalyst, ZA Patent 7924/72 and the corresponding US Patent 3,909,392 issued subsequently, which will be discussed in more detail below, describe the use, in conjunction with cracking catalysts, of catalysts and activating or initiating combustion agents within the regeneration zone which include rods metallic, mesh networks or screens in the combustion zone, and metallic compounds capable of being fluidized, in particular pulverulent oxides of transition metals - for example ferric oxide,

   manganese dioxide and rare earth oxides - either added to the catalyst charge or confined in the regenerator vessel. Patent BE 826.266 describes a process

  
very similar to that of the aforementioned US Pat. No. 3,909,392, which involves a catalytic cracking catalyst in physical association with a catalyst for initiating the oxidation of carbon monoxide, of a metal whose atomic number is at least of 20 and maintain metals of groups IB, IIB and III to VIII of the Periodic Table -

  
in particular platinum, palladium, rhodium, molybdenum, tungsten, copper, chromium, nickel, manganese, cobalt, vanadium, iron, cerium, ytterbium and uranium as useful oxidation initiation agents. In addition, US Pat. No. 3,C08,121 describes the regeneration of a cracking catalyst in the presence of a carbon monoxide oxidation catalyst, which is retained in the regeneration zone.

  
  <EMI ID = 5.1>

  
cracking containing less IDOppm, calculated as the metal, based on the total catalyst, of at least one metal component selected from

  
  <EMI ID = 6.1>

  
VIII of the Periodic Table, rhenium, and their compounds, which show particularly dramatic decreases in carbon monoxide content in flue gases from catalytic cracking catalysts. This patent also discloses a molecular sieve type cracking catalyst which; prepared in the sodium form, by ion exchange with ammonium ions and then impregnated with rare earth metals.

  
In addition, with regard to sulfur oxide emissions, although various methods have been developed for the treatment of flue gases, for example washing or scrubbing, chemical absorption, neutralization and reaction or chemical transformation, all these techniques for removing sulfur oxides require abundant and expensive auxiliary equipment,

  
thus increasing both capital and operating costs. One approach set forth in US Patent No. 3,699,037 contemplates the addition of at least a stoichiometric amount of a calcium or magnesium compound to the cracking cycle, in relation to the amount of sulfur deposition on it. the catalyst. This added material is intended to react with sulfur oxides

  
and thus, being conditionally, finely subdivided, comes out of the

  
cracking cycle as particulate matter in

  
the flow of combustion gas from the regeneration zone. The continuous addition of this material obviously increases the operating costs. Similarly, US Patents 3,030,300 and
3.030.314 describe a catalytic cracking process which involves the continuous addition to a moving bed cracking process cycle of one or more compounds of boron, alkali metals and alkaline earth metals to thereby provide particles of catalyst whose resistance is increased with respect to breaking by impact and surface abrasion and which comprises a siliceous catalyst particle having a microporous, catalytically active core which is provided with a protective coating adhering to a varnish or glaze comprising silica and one or more compounds of boron, alkali metals and alkaline earth metals.

  
  <EMI ID = 7.1> produces sulfur oxides in the regenerator flue gases. The process works with a catalyst which comprises a molecular sieve in a silica-alumina matrix, and which is impregnated with one or more oxides of the Group IIA metals. Licences

  
  <EMI ID = 8.1>

  
effecting the transformation of a noxious waste gas stream containing carbon monoxide and sulfur oxides which comprises contacting the stream with a catalytic composite mass of a refractory porous carrier material, a component catalytically active metallic, for example a metal of the platinum group and of an alkaline earth component selected from the group consisting of calcium, barium and strontium.

  
Until now, no one has described the process according to the present invention.

  
The present invention relates to a cyclic process for

  
  <EMI ID = 9.1>

  
emissions of carbon monoxide and sulfur oxides in the flue gases from the regeneration zone. According to several embodiments, the present invention also ensures substantially total combustion of carbon monoxide in the zone.

  
regeneration and absorption of the heat released during

  
of this combustion by solid particles which circulate towards the reaction zone and the stripping zone before returning to the regeneration zone. These solid particles include a molecular sieve type cracking catalyst and a metallic reagent and may also contain a cracking catalyst.

  
  <EMI ID = 10.1>

  
cracking hydrocarbons, and a metallic activating or priming agent. Alternatively, the metallic initiating agent can be retained within the regeneration zone.

  
The metallic initiating agent and / or a metallic reagent can be incorporated into the molecular sieve type cracking catalyst, the amorphous cracking catalyst and the substantially inert solid and can be circulated in the cycle of the process. cracking. This incorporation can be achieved either before or after the particulate support has been introduced into the cycle of the cracking process. Conditions are applied in the cycle of the cracking process such that a stable compound containing metal and sulfur is formed in the solid particles in the regeneration zone and a gas containing sulfur is withdrawn from the zone. counting.

  
The present invention is an improvement to the process for cyclic catalytic cracking in a fluidized bed, according to which the hydrocarbon feed containing organic sulfur compounds is subjected to cracking in a reaction zone, under fluidized conditions with homogeneous or non-homogeneous, regenerable solid particles, fluidised which comprise a molecular sieve type cracking catalyst, wherein the cracking catalyst is simultaneously deactivated by carbonaceous deposits containing

  
  <EMI ID = 11.1>

  
  <EMI ID = 12.1>

  
go through a counting area in which we remove

  
  <EMI ID = 13.1>

  
  <EMI ID = 14.1>

  
The fluidized solid particles are then separated from the gaseous effluent from the stripping zone and passed to a regeneration zone where the stripped deactivated cracking catalyst is regenerated at high activity by combustion of the stripped. carbonaceous deposits which cannot be removed, containing sulfur, from the deactivated, stripped cracking catalyst, in contact with a gas stream containing oxygen and with a metallic oxidation activating agent, thereby forming carbon monoxide carbon dioxide and sulfur oxides. The fluidized solid particles containing the regenerated cracking catalyst are separated from the flue gases which evolve from the regeneration zone and are recycled to the reaction zone.

  
The upgrade is to provide lower emissions of carbon monoxide and sulfur oxides in the regeneration zone flue gases, using solid particles which include (1) a molecular sieve type cracking catalyst, comprising a cracking catalyst matrix containing an alkali aluminosilicate distributed within the matrix and (2) a metallic reagent, which reacts with sulfur oxide to form a compound containing a metal and sulfur in such solid particles; using a skinning gas which contains water vapor; by regeneration of the deactivated cracking catalyst, stripped in the presence of a metallic agent promoting oxidation (for the oxidation of the oxide

  
carbon and sulfur oxide), at regeneration temperatures in a range in which the compound containing a

  
  <EMI ID = 15.1>

  
supplying a sufficient amount of oxygen to the regeneration zone in the stream of regeneration gas containing oxygen, so that combustion gases containing molecular oxygen can be withdrawn from the regeneration zone. Preferably, the solid particles additionally comprise the metallic initiator. Thus, the metallic initiator can either be confined in the regeneration zone or it circulates in the solid particles within the cycle of the catalytic cracking process.

  
The matrix of the cracking catalyst of the molecular sieve type cracking catalyst is preferably a combination of at least two materials selected from the group consisting of silica, alumina, zirconium dioxide, titanium dioxide. , magnesia, thorium oxide and boron oxide, and preferably silica-alumina. This cracking catalyst matrix preferably contains between about 10 and about 65,

  
  <EMI ID = 16.1>

  
cracking type. to. molecular sieve is preferably between about 10 and about 99.999, more preferably between about

  
30 and about 99.995 and especially between about 90 and about

  
  <EMI ID = 17.1>

  
The metallic initiating agent is chosen from the group consisting of at least a first metal whose atomic number is greater than 20 and preferably chosen from the group consisting of. killed by groups IB, IIB and III to VIII of the Periodic Table, and better still, chosen from the 5th and 6th periods of Group VIII of the Periodic Table, vanadium, silver and rhenium, better still from the group consisting of the 5th and 6th periods of group VIII and rhenium, and ideally chosen from the group consisting of platinum and palladium, their compounds and their mixtures.

   The metallic reagent is chosen from the group consisting of at least one second metal, preferably chosen from the group consisting of sodium, magnesium, calcium, strontium, barium, scandium, titanium, chromium, molybdenum , manganese, iron, cobalt, nickel, antimony, copper, zinc, cadmium, lead and rare earth metals better still chosen from the group consisting of sodium, magnesium, calcium , strontium, barium, scandium, titanium, chromium, molybdenum, manganese, cobalt, nickel, copper, zinc, cadmium, antimony, lead and rare earth metals, and better still, from the group consisting of sodium, magnesium, calcium, strontium, barium, chromium, manganese, copper, zinc, cadmium and rare earth metals,

   and ideally selected from the group consisting of sodium, magnesium, manganese and

  
copper, their compounds and their mixtures. The metallic reagent contains a second metal which is different from the first metal (s) in the metallic initiating agent.

  
The metallic initiating agent and the metallic reagent are present in an average amount sufficient to ensure a reduction in the emissions of carbon monoxide and sulfur oxides in the combustion gases of the regeneration zone. When the metal present is a metal chosen from the group consisting of ruthenium, rhodium, palladium, osmium, iridium, platinum, silver and rhenium, it is found at an average level,

  
  <EMI ID = 18.1>

  
per million solid particles. In the presence of a metal chosen from the group consisting of vanadium and copper, it is found at an average level, calculated as the metal, preferably

  
  <EMI ID = 19.1>

  
50 parts per million and about 250 parts per million of solid particles. When iron is present, it is found according to

  
  <EMI ID = 20.1> <EMI ID = 21.1>

  
solid. When the metal present is. a metal chosen from the group consisting of magnesium, zinc, calcium, cadmium, manganese, strontium, barium, scendium and cobalt, it is found at an average rate, calculated as a metal, included between about 25 parts per million and about 7% by weight better

  
  <EMI ID = 22.1>

  
solid ticles. In the presence of chromium, antimony or lead it is found at an average rate, calculated as a metal, preferably between about 10 parts per million and about

  
  <EMI ID = 23.1>

  
and about 250 parts per million of solid particles. When sodium is present, it is at an average level, calculated as sodium, preferably between about 0.6 and about 3% by weight, more preferably between about 0.8 and about 3% by weight.

  
  <EMI ID = 24.1>

  
is present, it is at an average level calculated as titanium, preferably between about 10 parts per million

  
  <EMI ID = 25.1>

  
by weight, more preferably between about 2 and about 6% by weight

  
  <EMI ID = 26.1>

  
solid particles. When nickel is present, it is at an average level, calculated as nickel, preferably between about 10 parts per million and about 10% by weight, more preferably between about 50 parts per million and about.

  
  <EMI ID = 27.1>

  
Certain individual solids in the solid particles of the process according to the present invention may contain an amount of at least one of the metallic initiating agent and the metallic reagent, which is greater than the average amount in the solid particles, at the same time. provided that some of these individual solids are mixed with other individual solids in the solid particles containing a smaller amount

  
at least one of the metallic initiating agent and the metallic reagent such that the solid particles contain the average levels of metallic initiating agent and metallic reagent previously indicated.

  
The stripped deactivated catalyst is regenerated at regeneration temperatures in the range for which a stable compound containing the metal and sulfur is formed in the solid particles from the metal in the metal reactant and the sulfur oxide. Regeneration temperatures are pre-

  
  <EMI ID = 28.1>

  
of the hydrocarbon feed at reaction temperatures in

  
the range for which the compound containing a metal and sulfur in the solid particles reacts to form a sulfide of the metal in the metal reactant. The cracking temperature is pre-

  
  <EMI ID = 29.1>

  
removable deposits are stripped of the deactivated cracking catalyst with a gas containing water vapor and at temperatures

  
  <EMI ID = 30.1> in the metallic reagent reacts with water to form hydrogen sulfide gas. The skinning temperatures are

  
  <EMI ID = 31.1>

  
  <EMI ID = 32.1>

  
weight between steam and molecular sieve type cracking catalyst to be supplied to the stripping zone is preferably in the range of about 0.0005 to about 0.025 and more preferably in the range of about 0.0015 to about 0.0125. The combustion gases from the regeneration zone preferably contain at least 0.01% by volume and more preferably

  
  <EMI ID = 33.1>

  
to the desired reduction in harmful gas emissions.

  
According to one of the embodiments of the present invention, at least one of the metallic initiators and

  
  <EMI ID = 34.1>

  
wire mesh type. In this case, one at. less of the metallic initiating agent and metallic reagent is incorporated either in the crystalline aluminosilicate or in the matrix of the molecular sieve type cracking catalyst. According to another form of implementation of the present invention, the solid particles additionally comprise at least one material chosen from

  
the group consisting of solids which are practically inert with respect to cracking of the hydrocarbon feed and a catalyst

  
amorphous cracking; and at least one of the metallic initiating agents and metallic reactants is incorporated into this material. According to yet another form of implementation of the present invention, at least one of the metallic initiating agent and of the metallic reagent is itself a solid in the solid particles.

  
Metallic initiating agent or metallic reagent,

  
or both, can be incorporated into the solid particles

  
either outside or within the cycle of the catalytic cracking process, which includes the cracking reaction zone, the

  
skinning area and regeneration area. If incorporated during the cycle of the catalytic cracking process, one au; less metallic initiating agent and metallic reagent

  
can then be introduced into the fluidized bed catalytic cracking process cycle, in the form of a compound soluble or dispersible in oil or in water, of the metal or metals in

  
  <EMI ID = 35.1>

  
!

  
  <EMI ID = 36.1>

  
  <EMI ID = 37.1>

  
such compound is selected from the group consisting of metal diketonates, metal carbonyls, metallocenes,

  
metal complexes of olefins having 2 to 20 carbon atoms

  
  <EMI ID = 38.1>

  
  <EMI ID = 39.1>

  
liques having 1 to 20 carbon atoms. More preferably, one of these compounds is platinum acetylacetonate.

  
The present invention relates to an improved method

  
fluid catalytic cracking, comprising an improved process for regenerating the cracking catalyst used in the fluid catalytic transformation and an improved process for decreasing emissions of carbon monoxide and sulfur oxides in the effluent gas from the catalyst regeneration zone cracking, involving the transformation of hydrocarbon feeds containing sulfur in which the cracking catalyst is deactivated by depositing coke containing sulfur on the surface of the cracking catalyst.

   The solid particles are circulated according to the process of the present invention, which comprise a molecular sieve type cracking catalyst, in well-dispersed physical association with another, through the cycle of the cracking process, which includes the cracking zone. , the skinning area and the regeneration area. The conditions applied allow to achieve a reduction of carbon monoxide and sulfur oxides in the flue gases in the regenerator zone.

  
The cracking catalyst, the metallic initiating agent and the metallic reagent of the process according to the present invention serve separate and essential functions. The catalyst

  
cracking agent serves to catalyze the cracking reaction, while the metallic initiator and metallic compound are practically inert to the cracking reaction and do not

  
little or no adverse effect, if any, on the operation

  
catalytic transformation under the applied conditions. In

  
with regard to the combustion of carbon monoxide, all metals and their compounds which suitably serve as a metallic initiating agent, catalyze the oxidation of the oxide

  
of carbon to carbon dioxide in the regeneration zone. In this

  
Regarding the decrease of sulfur oxides in the combustion gas of the regeneration zone, the solid particles adsorb the sulfur oxides in the regeneration zone. The molecular sieve type cracking catalyst itself often serves as an adsorbent for sulfur oxides. The metallic initiating agent catalyzes the oxidation of sulfur oxide or a sulfur oxide group in a metallic compound, and the metallic reagent reacts with the adsorbed sulfur oxides to form a compound containing a metal and sulfur, in particular a metal sulfate, in the solid particles.

   Provided that this compound containing a metal and sulfur is stable under the operating conditions in the regeneration zone, !! can be transported to the surface of the solid particles in the reaction zone and the stripping zone where it is reduced and separated as

  
gas containing sulfur, in particular hydrogen sulphide.

J

  
It is understood that the activity relating to the decrease in the emission of carbon monoxide and sulfur oxides in

  
  <EMI ID = 40.1>

  
  <EMI ID = 41.1>

  
  <EMI ID = 42.1>

  
metallic. Similarly, many specific metals which may serve as the metal in the metallic initiator and metallic reagent do not necessarily provide equivalent results, compared with other specific metals which may be used in the initiator. metallic initiating agent or metallic reagent, respectively or when applied in

  
varying conditions.

  
The solid particles of the process according to the invention,

  
are finely divided and have, for example, a particle size of between about 20 microns or less and about

  
150 microns, so that they are in a form suitable for fluidization. Suitable cracking catalyst matrices include those containing silica and / or alumina. Other refractory metal oxides can be used, being limited only by their ability to be effective.

  
  <EMI ID = 43.1>

  
use mixtures of aluminas elongated with clays. Preferred catalysts include combinations of silica and alumina, in admixture with "molecular sieves" also known as zeolites or crystalline aluminosilicates. Suitable cracking catalysts contain a sufficient amount of crystalline aluminosilicate to materially increase the cracking activity of the catalyst, being limited only by their ability to be efficiently regenerated under the conditions selected. Crystalline aluminosilicates usually have molecular proportions between silica and alumina of at least about 2: 1, for example about 2 to 12: 1, preferably about 4 to about 6: 1.

   Suitable silica-based cracking catalysts have a major proportion of silica, for example between about 35 and about 90% by weight silica and between about 10 and about 65% by weight alumina. These catalysts can be prepared by any suitable method, such as grinding, co-gelation and the like, subject only to the condition of providing the finished catalyst in a physical form capable of fluidization.

  
Suitable molecular sieves include both naturally occurring materials and synthetic aluminosilicates, such as faujasite, chabazite, X-type and Y-type aluminosilicate materials, and "ultrastable" crystalline aluminosilicate materials. large pores. When it is mixed, for example with silica -alumina to provide

  
a petroleum cracking catalyst, the molecular sieve content of the particles of newly prepared catalyst is suitably between about 0.5 and about 50% by weight, of

  
  <EMI ID = 44.1>

  
Crystalline silicates are usually available or made in the sodium form; the sodium component is then lowered to as low a content as possible, generally less than about 0.30% by weight, by ion exchange with hydrogen ions, precursors of hydrogen, such as ammonium ions, or polyvalent metal ions, including calcium, strontium, barium and rare earths, such as cerium, lanthanum, neodymium, and rare earths occurring in nature and their mixtures. The crystalline materials which can be used are able to maintain their pore structure under the high temperature conditions of catalyst manufacture, hydrocarbon treatment and catalyst regeneration.

   Crystalline aluminosilicates often have a uniform pore structure, of excessively small size, the cross-sectional pore diameter being between about 6 and about 20 Angstroms, preferably between about 10 and about 15 Angstroms.

  
Catalytic cracking of heavy ends of mineral oils is one of the main refining operations applied when converting crude oils into desirable fuel products such as high octane gasoline used in internal combustion ignition engines. by spark.

   Among the illustrative processes of "fluidized" catalytic transformation is the fluidized bed catalytic cracking process in which high molecular weight hydrocarbon liquids or vapors are contacted with particles of hot, finely divided solid catalyst or fluidized bed reactor, either in an extended riser reaction, and the mixture of hydrocarbon and catalyst is maintained at an elevated temperature in a fluidized or dispersed state for a time sufficient to effect the desired degree of cracking in hydro-

  
  <EMI ID = 45.1>

  
present in motor gasoline and fuel distillates.

  
Hydrocarbon feedstocks suitable for the

  
cracked usually boil above the boiling range

  
1

  
  <EMI ID = 46.1>

  
are generally cracked at a temperature between approximately

  
  <EMI ID = 47.1>

  
mineral oil boiling above the gasoline range such as light gas oils, heavy gas oils, wide cut gas oils, vacuum distillation gas oils, kerosene, decanted oils, residual fractions, reduced crude oils, recycle oils from any of the foregoing, as well as suitable fractions from shale processing oils, tar sands, synthetic oils, coal liquefaction and the like. We can-. use these fractions singly or in any desired combination. '

  
The process according to the present invention can be applied according to any conventional catalytic cracking scheme, but it is advantageously carried out in a fluidized bed catalytic cracking system in which at least a significant portion of the conversion of the hydrocarbons takes place in a dilute phase or reactor transfer piping system

  
riser, using highly active catalysts applied with relatively high space velocities. Preferably

  
cracking occurs essentially exclusively in the riser reactor and a subsequent dense catalyst bed is not used for cracking. In a typical case in which lift cracking is applied for converting a gas oil, the yield ratio, or volume ratio between the total and recent charges, may vary between approximately 1 and 3. The conversion rate can vary between approximately
40 and 10'0% by weight, and advantageously it is maintained above

  
  <EMI ID = 48.1>

  
The term "transformation" denotes the percentage reduction in weight of hydrocarbons boiling above about 222 [deg.] C, at atmospheric pressure, by formation of lighter materials or coke. The weight ratio of the total cracking catalyst to the oil in the riser reactor can vary between about 2 and about 20 so that the fluidized dispersion has a density of between about 16.0185 and 320.37 kg / m3 . Desirably the ratio of catalyst to oil is kept between about 3 and about 20, preferably between about 3 and about 7. The rate of fluidization in the lift reactor can be between about 304.8 and about 3048. cm / sec.

  
The riser reactor generally has a length to average diameter ratio of about 25. For the production of a typical naphtha product, the mixing temperature is maintained at the bottom of the reactor, within the riser reaction. preferably between about 538 and about 595 [deg.] C, for vaporization of the oil charge and so that the temperature

  
  <EMI ID = 49.1>

  
cracking of residual and synthetic fuels, significantly higher temperatures would be required. Under these conditions including providing rapid separation of the spent catalyst from the effluent oil vapor, it is established.

  
a very brief period of contact between the catalyst and the oil.

  
The duration of the contact in a riser reactor is generally between about 1 and 15 seconds, preferably about 3 and about 10 seconds. Short contact times are preferred because most of the cracking of the hydrocarbon occurs during the first part of the contact time and

  
that unwanted side reactions are avoided. This is especially important in order to achieve higher yield and selectivity to product, including lower coke production.

  
A short duration of contact between the catalyst particles and oil vapors can be achieved by various means. For example, the catalyst can be injected at one or more points along the bottom section or at the bottom of the riser. Similarly, the oil charge can be injected at any point along the length of the bottom section of the

  
  <EMI ID = 50.1>

  
different tion for the new charge and recycling currents:

  
The lower section of the riser reactor may include,

  
  <EMI ID = 51.1>

  
with a riser so as to ensure extremely short effective contact times, leading to an optimal transformation of the petroleum feedstocks. When using a dense catalyst bed, provision should also be made for injecting the catalyst and / or oil feed particles directly into the zone of the catalyst.

  
dense bed.

  
Although the processing conditions previously discussed are directed towards the production of gasoline, as a fuel for spark ignition internal combustion engines, the processing scheme can be appropriately modified to allow maximum production of hydro carbon products. heavier, such as jet propellant fuels, diesel fuel, heating oils and chemicals, especially olefins and aromatics.

  
In the catalytic process certain non-volatile charcoal products or "coke" are deposited on the catalyst particles. Coke is composed of highly condensed aromatic hydrocarbons which generally contain a minor amount of hydrogen, namely between about 4 and about 10% by weight. When the hydrocarbon feed contains organic compounds

  
sulfur, coke also contains sulfur. As the coke builds up on the catalyst, the activity of the catalyst for cracking and the selectivity of the catalyst for producing gasoline blends decrease. The catalyst particles can regain the major proportion of their original qualities by removing most of the coke in a regeneration process.

  
  <EMI ID = 52.1>

  
  <EMI ID = 53.1>

  
formation of oil is stripped prior to its entry into the regenerator. The stripping vessel for application in a fluidized bed catalytic cracking plant can be suitably maintained, essentially at the reactor process temperature, in the range of from about 455 to about
650 [deg.] C and maintained desirably at a higher value.

  
  <EMI ID = 54.1>

  
is water vapor, although water vapor containing nitrogen or other inert or combustion gas can also be used with steam. The stripping gas is introduced under a pressure which is generally at least about 0.7, preferably about 2.45 kg / cm2 at an appropriate pressure gauge to effect substantially complete removal of the volatiles.

  
from the spent transformation catalyst.

  
The process according to the invention can be applied with any conventional catalyst regeneration scheme, but advantageously, it is applied with a regeneration system involving at least one dense bed and at least one dilute phase zone. Spent catalyst particles, subjected to extraction treatment, can enter the dense bed section

  
from the regenerator vessel by suitable pipes from

  
of the counting vessel. Entrance can be done through the

  
bottom or side, desirably close to the top of the

  
dense bed fluidized zone. Entry can also be through the top of the regenerator when the catalyst has first been in contact with substantially exhausted regeneration gas in a restricted dilute phase zone.

  
Catalyst regeneration takes place by burning

  
coke deposits on the surface of the catalyst with an oxygen-containing gas such as air. Numerous regeneration techniques are practiced industrially with which restoration of catalyst activity is achieved in response to the degree of coke removal. As the coke is gradually removed from the catalyst, the removal of residual coke becomes more difficult and, in practice, an intermediate level of restored catalyst activity is accepted as an economic compromise.

  
The combustion of coke deposits from the catalyst requires a large volume of oxygen or air. Although the present invention is not limited to the following considerations, it is believed that the oxidation of coke can be characterized in a simplified manner as the oxidation of carbon and represented by the following chemical equations:

  

  <EMI ID = 55.1>


  
Reactions (a) and (b) both take place under the characteristic conditions for regeneration of the catalyst,

  
in which the temperature range can be from about 566 to 788 [deg.] C, and are examples of the gas-solid chemical interactions when the catalyst is regenerated at temperatures within this range. The effect of any increase in temperature is reflected in an increase in the burn rate

  
carbon and more complete removal of carbon or coke from catalyst particles. As the combustion rate increases, it is accompanied by a greater release of heat as long as there is a sufficient amount of free or molecular oxygen present, the gas phase reaction (c) may happen. This latter reaction is initiated and propagated by free radicals and can be catalyzed.

  
The combustion of coke deposits containing sulfur from the catalyst also results in the formation of oxy-; des sulfur and, the present invention not being limited by the following, this combustion can be represented by the following chemical equations:

  

  <EMI ID = 56.1>


  
Reactions (d) and (e) can also take place under the characteristic conditions for regeneration of the cracking catalyst. While reaction (d) is fast, reaction (e) is relatively slow. Reaction (e) can be catalyzed using any catalyst which catalyzes the preceding reaction (c). Molecular sieves adsorb oxides of sulfur and therefore reaction (e) can take place on the cracking catalyst in solid particles by the process according to the present invention. Other components of the solid particles can also adsorb sulfur oxides. The resulting sulfur trioxide can then react with a suitable metal, or more particularly an oxide of the metal in the metal reagent, to form a stable metal sulfate in the solid particles.

  
When the solid particles are separated from the combustion gases of the regeneration zone, the metal sulfate in the solid particles circulates in the reaction zone. Thus the sulfur is made unavailable for emission as gaseous sulfur oxides in the combustion gas of the regeneration zone.

  
The sulphate remains on the solid particles as they pass through the cracking reaction zone and, in the reducing atmosphere therein, changes to the metal sulphide in the metal reactant and possibly also to hydrogen sulphide. By stripping with a stripping gas containing water vapor, in the stripping zone, the sulfur is converted to hydrogen sulphide and exits in the effluent stream of the stripping zone. In this way, the metallic reagent is regenerated and made available again for the reaction with sulfur oxides during the next passage through the regeneration zone. The hydrogen sulfide can then be recovered with the cracked products from the stripping zone, separated and converted to elemental sulfur in conventional devices.

  
  <EMI ID = 57.1>

  
it is believed that these reactions can be summarized as follows:

  

  <EMI ID = 58.1>


  
where x represents the proportion between the oxidation state of the oxide ion and the oxidation state of the metal in the metallic reagent

  
in combination with oxygen.

  
These reactions are made possible by the molecular sieve type cracking catalyst, the metallic initiator and the metallic reagent of the process according to the invention. The high cracking activity normally present in the molecular sieve catalyst is substantially unaffected by the presence of either the metallic initiating agent or the metallic reactant, so that the intended transformation of the feed is achieved. and the yield of cracked products, together with a decrease in the emission of carbon monoxide and oxides of sulfur.

  
The metallic initiating agent can be a solid which is confined in the regeneration zone. The metallic initiator and metallic reagent, or both, can also be in finely divided form, such as a powder, separated from the molecular sieve type cracking catalyst or any other support. The metallic initiator or metallic reagent, or both, may be a powder which

  
it is mixed with the catalytic cracking catalyst and which circulates in the cycle of the catalytic cracking process. In general, such a metallic initiating agent or a metallic reagent or both, in powder form is advantageous in that a powder is easy to charge and handle in a fluidized bed catalytic cracking system. The particle size size of the powder should be chosen so as to avoid particle separation at fluidization rates.

   Desirably, the particles in such a powder are not small enough to cause a problem, such as excessive emission with the gases from the bed as entrained particulate matter; however, filters, cyclones, precipitators and the like are usually used in conjunction with fluidized bed catalytic cracking operations to recover most of the entrained particulate matter and return it to the system to reduce losses. The powder should be strong enough to prevent excessive wear and friction degradation of the sieved powder. Frequently, the average particle size of the metallic initiating agent and the powdered metallic reagent, or both, is common.

  
  <EMI ID = 59.1>

  
greater than about 50 microns in diameter. It has been noted that micro-dimensional particles, that is to say whose average particle size is less than about 1 micron, for example

  
  <EMI ID = 60.1>

  
larger in size which can be used to advantage in the process of the present invention. Illustrative examples of metallic initiators and metallic reagents

  
  <EMI ID = 61.1>

  
ferrous, zinc oxide, manganese dioxide, cerium oxide and similar compounds, dolomite and "Trimex" (manufactured

  
  <EMI ID = 62.1>

  
Alternatively, the metallic initiating agent or the metallic reagent, or both, may be incorporated into a suitable carrier. Metal initiating agent and metal reagent can be incorporated into the carrier simultaneously

  
or at different times and by identical or different methods of incorporation. This support can be a catalyst

  
cracking or a solid which is substantially inert to the cracking reaction and may for example be ceramic in nature. In a similar case, the supported metallic initiating agent or metallic reagent, or both, can then be mixed with the molecular sieve type cracking catalyst. Desirably, the support is porous and frequently has a specific surface area, including pore to surface area of at least about 10, and preferably at least 50 m2 / g. Illustrative examples of such supports are silica, alumina, silica-alumina and the like.

   By varying the metallic initiating agent or the metallic reagent, or both, may be incorporated in the molecular sieve type cracking catalyst or in a portion thereof, in the solid particles according to the method of present invention. In which case, the metallic initiating agent or the metallic reagent, or both, can be introduced into the matrix of the cracking catalyst during the manufacture of the catalyst, or they may be impregnated on the structure of the cracking catalyst. . In this case, care should be taken in choosing the method of incorporation, so that the activity

  
  <EMI ID = 63.1>

  
  <EMI ID = 64.1>

  
  <EMI ID = 65.1>

  
the ion exchange is completed before the incorporation of metallic initiator and / or metallic reagent.

  
In any of the preceding cases, it is not known with absolute certainty the precise manner in which the metal (s) of the metallic initiating agent or of the metallic reactant, or both, are incorporated into the cracking catalyst. of the molecular sieve type, in the amorphous cracking catalyst or a substantially inert support. The metals can enter into complex combination with the carrier material and other components of the solid particles according to the invention. Therefore, it is understood that the use of the terms "metallic initiating agent" and "metallic reagent" and "incorporated into" the support refer to the metals of these components existing on the support material in elemental state and / or in combined form.

  
The metallic initiating agent and / or the metallic reagent can be incorporated into the support by ion exchange, by impregnation or by other means, by contacting the support or one of its components with one or more solutions. of a compound (s) of the metal (s) in the metallic initiating agent or metallic reagent, or both, in an appropriate amount necessary to ensure the desired concentration of metallic initiating agent or metallic reagent, or two, within the scope of the present invention.

  
The metallic initiating agent and / or metallic reagent can be combined with the support either at any stage in the preparation of the support or after the support has been prepared. One mode of incorporation is ion exchange with the support. For example, it is preferred to carry out a crystalline aluminosilicate ion exchange with one or more solutions of one or more compounds of the metal (s) in the metallic initiating agent or the

  
metallic reagent, or both, and then prepare a material

  
  Porous cracked <EMI ID = 66.1>. Ion exchange of siliceous solids or clays with a solution (s) of a compound (s) of the metal (s) in the metallic initiator or metallic reagent, or both, is also useful. Suitable compounds in this

  
but include metal halides, preferably chlorides, nitrates, amine halides, oxides, sulfates, phosphates and other water-soluble inorganic salts.

  
  <EMI ID = 67.1>

  
bone and alcoholates. Specific examples include palladium chloride, chloroplatinic acid, chloride

  
  <EMI ID = 68.1>

  
dioxo-bis (ethylene diamine) -rhenium (V) chloride, rhodium chloride and the like.

  
Another method of preparing a metallic initiator or metallic reagent, or both, usable according to the present invention is the impregnation of a suitable support with one or more compounds of the metal or metals dispersible or soluble in the. water or in an organic solvent, in the metallic initiating agent and / or the metallic reagent. The impregnation can be carried out in any way which does not destroy the structure of the support. The metallic initiating agent, or the metallic reactant, or both, can be impregnated on a carrier inert to hydrocarbon cracking, the α-type cracking catalyst. molecular sieve or amorphous cracking catalyst. Impregnation is different from cation exchange.

  
Impregnation results in the greater deposition and predominantly physical association on the support surface, while ion exchange results in predominantly association
- chemical and to greater diffusion and consequently to less surface deposition. In the impregnation, the metal is deposited and no significant ion exchange occurs between the metal and the support. In the impregnation of a support the metal (s) in the metallic initiating agent or the metallic reagent or both, may be present in or in the form of one or more compounds soluble or dispersible in water or in an organic solvent, and an amount or amounts sufficient to contain the amount of the desired metal (s) on the support, and the support is contacted therewith.

   The composite material can be dried to remove the solvent, leaving the metallic initiating agent or metallic reagent or both to deposit on the support.

  
Preferably, water soluble salts of the nitrate type are used in the impregnation solution, since the residue from thermal decomposition of nitrates is relatively harmless to the activity of the cracking catalyst.

  
of hydrocarbons. It is also possible to use salts of the type

  
halogenated or sulphates of the metal to be impregnated, however, due to

  
that halogens or sulphides may be released during

  
thermal degradation of the salt and can be harmful to the Inactivity of the hydrocarbon cracking catalyst, these salts are most often used when depositing the metallic initiating agent or the metallic reagent or both on supports which are substantially inert in the cracking reaction which does not materially adversely affect the catalytic cracking reaction.

  
  <EMI ID = 69.1>

  
metallic or metallic reagent or both on a support,

  
in particular porous supports such as crystalline aluminosilicates, is the adsorption of a liquid compound (s) of the decomposable metal (s), in the metallic initiating agent or the metallic reagent or both, on the support followed by a chemical or thermal decomposition of the compound (s). The support can be activated by heating to remove any adsorbed water and then contact with one or more decomposable liquid compounds of the metal (s), in the metal initiating agent.

  
or the metallic reagent or both, with adsorption of the compound (s) to the support. Typical examples of these compounds are carbonyl metals, alkyl metals, volatile metal halides and the like. The adsorbed compound (s) can then be thermally or chemically reduced to the active state, thereby leaving uniformly dispersed on the support an initiating agent or an active metallic reagent, or both. The thermal reduction can be carried out for example in the regeneration vessel during the regeneration process.

  
Impregnation and adsorption can be carried out

  
with a support before the introduction into the cracking process cycle. However, it is also advantageous to introduce one or more compounds of the metal or metals into a metallic initiating agent or

  
a metallic reagent or both, in the cracking process cycle and to incorporate them in situ in the support. This or these compounds can be introduced in dispersible or soluble form.

  
in oil or water, and in solid, liquid or gaseous state,

  
any stage of the cracking process cycle so

  
that we achieve a wide distribution in the particles

  
solid. For example, this or these compounds can be mixed either

  
with the feed or the fluidizing gas in the reaction zone,

  
with regeneration gas, torch oil or water in the

  
regeneration zone, or with the stripping gas in the stripping zone or it can be introduced as a separate stream.

  
Suitable compounds for in situ incorporation include

  
metal salts, organometallic compounds, metal diketonates, carbonyls, metallocenes, olefin complexes of 2 to 20 carbon atoms, acetylene complexes

  
or complexes of alkyl- or aryl-phosphines and carboxylates of 1 to 20 carbon atoms. Specific examples of these are platinum acetylacetonate, tris (acetylacetonato) -rhodium (III), tri-iodoiridium (III) -tricarbonyl, cyclopentadienyl-rhenium- (I) -tricarbonyl, ruthenocene , cyclopentadienyl-sodium (I) -dicarbonyl dimer, dichloro (ethylene) -palladium (II) dimer, cyclopentadienyl- (ethylene) -rhodium (I), diphenyl-acetylene-bis (triphenylphosphino) -platin- (O), bromo-ethyl-bis (triethylphosphino) -palladium (II), tetrakis-
(triphenylphosphine) -palladium (O), chlorocarbonyl-bis- (tri-phenylphosphine) -iridium (I), palladium acetate, palladium naphthenate and zinc-dimethyl and zinc-diethyl.

  
Key features are easier to reach

  
of activity and stability by introducing at least one metallic initiator and metallic reagent to produce reduced releases of carbon monoxide and sulfur oxides in the cracking process cycle, and the incorporation in

  
the solid particles in situ, rather than compositing with the catalyst. cracking during the manufacture of the cracking catalyst. It was found that the introduction of at least

  
a metallic initiator and metallic reagent in the

  
cycle of the cracking process and its incorporation in situ as opposed to composition with the cracking catalyst

  
during the preparation of the cracking catalyst gives rise

  
to a greater reduction in the emission of carbon monoxide

  
  <EMI ID = 70.1>

  
regeneration. The incorporation of at least one metallic initiator and metallic reactant during the cracking cycle is also advantageous because it allows to maintain a greater degree of control over any potential harmful effects of this metallic initiator and / or of the metallic reagent on the cracking reaction because the rate and / or the quantity of this metallic initiator and / or of the metallic reagent introduced into the cracking cycle may vary. Likewise, this metallic initiating agent and / or this metallic reagent, previously compounded with the cracking catalyst before the introduction of the catalyst into the cycle of the cracking process, can be lost under

  
  <EMI ID = 71.1>

  
cracking. The addition of the metallic initiating agent and / or the metallic reagent to the cracking cycle and its incorporation into the solid particles in situ makes it possible to maintain the desired amount of initiating agent and / or metallic reagent at the cracking cycle. surface or on the accessible portions of the solid particles.

  
Another method involves the incorporation of an initiator or a metallic reagent, or both, with a precursor of the carrier, for example a silica gel or a silica gel -alumina before spray drying or the like. physical shaping process, and the precursor is dried to prepare the support. The resulting support body can be calcined to form the active material. Alternatively, heat treatment can be performed in the cracking cycle.

  
According to a preferred embodiment of the present invention, the metallic reagent is mainly in physical association with the cracking catalyst of the molecular sieve type and is chosen from the group consisting of

  
sodium and rare earth metals, their compounds and mixtures. By applying this form of implementation, it is possible to combine the metal or metals of the metallic reactant with the catalyst.

  
molecular sieve type cracking by any process which does not result in significant chemical incorporation of; this or these metals in the crystalline aluminosilicate portion of the cracking catalyst. Accordingly, according to this form of betting

  
the metallic reagent cannot be incorporated into the molecular sieve type cracking catalyst by exchange.

  
ion. With the exception of the ion exchange on the molecular sieve type cracking catalyst, however, the previously indicated techniques for the incorporation of the metallic reagent

  
in the substrate are generally suitable for application in

  
the implementation of this embodiment.

  
A main advantage resulting from the process according to the invention is the unusually low content of carbon monoxide in the effluent gas stream from the regenerator, at which one

  
can achieve. While the flue gas from conventional regeneration of cracking catalysts usually contains between about 6 and 10 carbon monoxide, a similar amount of carbon dioxide and very little oxygen, the content of

  
carbon monoxide of the combustion gas from this process

  
new regeneration can be kept at less than 0.2 volume

  
% approximately, for example between approximately 500 and 1000 parts per

  
million by volume (ppmv). Advantageously, the content is even

  
even lower, for example between 0 and about 500 ppmv. This low concentration of carbon monoxide in the gas stream

  
combustion allows the direct discharge of the effluent gases into the atmosphere, while meeting ambient air quality standards. If necessary, you can burn

  
  <EMI ID = 72.1>

  
  <EMI ID = 73.1>

  
; of the present invention also allows the elimination of costs

  
  <EMI ID = 74.1>

  
  <EMI ID = 75.1>

  
  <EMI ID = 76.1>

  
energy produced by the subsequent oxidation of carbon monoxide, while meeting existing ambient air quality standards for carbon monoxide emissions.

  
The method according to the present invention provides additional advantages. These advantages relate to the problem of thermal equilibrium and the "post-combustion" or combustion of carbon monoxide and entrained coke particles in the dilute phase of a coke burner or catalyst regenerator. A main problem, often encountered and that we are looking for

  
to be avoided in practice, particularly in the regeneration of catalyst in a fluidized bed, is the phenomenon referred to as "post-combustion", as described for example by Hengstebeck "Petroleum Processing", McGraw-Hill Book C [deg.], 1959, at pages

  
160 and 165 and discussed in "Oil and Gas Journal", Volume 53

  
(N [deg.] 3), 1955 at pages 93 and 94. This term describes a subsequent combustion of carbon monoxide to carbon dioxide, as represented by the preceding reaction (c), and which is highly exothermic. Afterburning has been strictly avoided in catalyst regeneration processes because it could lead to very high temperatures which could damage equipment and cause permanent deactivation of the cracked catalyst particles. After-combustion has been observed during numerous fluidized bed catalyst regenerator operations, and a very significant portion of this technique has developed around the various means for regulating regeneration techniques, so as to avoid this after-combustion. .

   More recently, attempts have been made to raise the temperature of the regenerator for various reasons; Complicated arrangements have also been developed to control the temperatures of the regenerator at the point of onset of post-combustion by suitable means for controlling the oxygen supply to the regenerator vessel as disclosed for example in US Pat. deg.] 3,161,583 and 3,206,393 as well as in the

  
US Patent N [deg.] 3,513,087. Accordingly, according to typical current practice, by avoiding post-combustion, the combustion gas from catalyst regenerators usually contains very little oxygen and a large amount.

  
of carbon monoxide and carbon dioxide in practical amounts

  
equimolar.

  
Subsequent combustion of carbon monoxide to carbon dioxide is a reducing source of thermal energy because reaction (c) is highly exothermic. Afterburning can occur at temperatures above about 593 [deg.] C and releases approximately 2416.69 calorie-grams / gram of oxide.

  
of oxidized carbon. This is typically about a quarter of the heat release which can be obtained from the combustion of coke. The combustion of carbon monoxide can be carried out in a controlled manner in a separate zone or boiler

  
of carbon monoxide, after separation of the effluent gas from the catalyst

  
sor, as described for example in US Pat. No. 2,753,925, the thermal energy released being used in various operations.

  
  <EMI ID = 77.1>

  
  <EMI ID = 78.1>

  
  <EMI ID = 79.1>

  
  <EMI ID = 80.1>

  
petroleum load). These thermal recovery processes require separate and complicated equipment, but they serve to minimize the discharge of carbon monoxide into the atmosphere as a component of the flue gases and therefore serve to avoid

  
a potentially serious risk of pollution.

  
In addition) silica-alumina catalysts conventionally used for many years in various processes for cracking petroleum hydrocarbons :, are not particularly;

  
  <EMI ID = 81.1> <EMI ID = 82.1>

  
weight. However, silica-alumina catalysts have been widely used.

  
  <EMI ID = 83.1>

  
posing incorporated crystalline aluminosilicate and known as zeolites or molecular sieves. The catalysts containing a molecular sieve are much more sensitive to the level of residual coke being strongly influenced both with regard to the activity of the catalyst and the selectivity of the catalyst for the transformation of feed into the desired product (s). Due to the difficulties encountered in conventional catalyst regeneration techniques for removing the last portions of residual carbon, the practical level of coke usually corresponds to the residual coke content on the regenerated catalyst, between about

  
0.2 and about 0.3% by weight.

  
Because improved activity and selectivity can be achieved with molecular sieve type cracking catalysts at low coke levels, an attractive stimulation is offered to find a way to lower residual coke levels even more. Coke levels below approximately

  
  <EMI ID = 84.1>

  
achieve this by industrially practicable means. Considerations such as larger regeneration vessels, larger catalyst inventory, greater heat losses and the like all serve to discourage achieving such an ideal balance of catalyst activity levels.

  
Preferred forms of carrying out the method according to the invention involve an operation in conjunction with the scheme.

  
  <EMI ID = 85.1>

  
'cited in full by way of reference, relates to an improved catalytic cracking process, comprising an improved process.

  
  <EMI ID = 86.1> Catalytic fluidized bed of hydrocarbon feedstocks, during which the catalyst is deactivated by depositing coke on the surfaces of the catalyst. The process makes it possible to keep the coke on the regenerated catalyst at an extremely low level, while simultaneously maintaining a favorable thermal equilibrium in the
- the transformation installation and supplying a stream of combustion gas with an extremely low carbon monoxide content. The heat from the combustion of carbon monoxide is absorbed by the regenerated catalyst and provides part of the process heat required in the transformation zone of

  
1 hydrocarbon. According to one of the embodiments of the process of this patent, the combustion of carbon monoxide into carbon dioxide takes place practically until exhaustion within the container.

  
  <EMI ID = 87.1>

  
partially regenerated catalyst from the primary regeneration zone of relatively dense catalyst can flow through the secondary zone in a controlled manner in quantity and quantity.

  
rates sufficient to absorb virtually all of the heat

  
caused by combustion occurring in the secondary zone.

  
Although most of the coke is burned in the primary zone, additional coke from the partially regenerated catalyst is burnt while it is present in the secondary zone, and the practical catalyst can be recovered.

  
coke free for recycling at conversion level

  
of the hydrocarbon.

  
According to a second form of implementation of the method

  
  <EMI ID = 88.1> tion, including both coke or carbon oxidation on the catalyst and the oxidation of carbon monoxide, occurs in a single zone of relatively dense phase regeneration in response to appropriate regulation mainly from the regeneration temperature and gas velocity.

  
Similarly, when the method according to the present invention operates according to the embodiments involving

  
  <EMI ID = 89.1>

  
part of the heat released during the combustion of carbon monoxide in the regeneration zone is absorbed by the solid particles of this invention which comprise the cracking catalyst and provides part of the heat required in the zone

  
cracking. Advantageously in these forms of implementation

  
work, the process according to the present invention allows the combustion of a considerable quantity of coke and carbon monoxide in

  
the dense phase zone, if there is one, where there is present a significantly greater quantity of solid particles, compared to the dilute phase zone, if there is one, to disperse the heat released. As the portion of combustion which occurs in the dense phase zone increases, the evolution of heat in the dilute phase zone is markedly reduced, therefore, the need to ensure rapid rotation of the solid particles.

  
in the area diluted to absorb the heat released is lessened or eliminated.

  
In these embodiments, the process encompasses the use of the solid particles according to the present invention.

  
which include a molecular sieve type cracking catalyst

  
  <EMI ID = 90.1>

  
metallic reactant of the present process, in a system which maintains substantially complete combustion of carbon monoxide. The low coke levels on the catalyst are lower than in --- <EMI ID = 91.1>

  
process can lead to the result that the flue gas has

  
carbon monoxide levels of less than about 0.2% by volume eg about 500 to 1000 parts per million and as low as about 0 to about 500 parts per million. The process also involves recovering the heat released by transfer directly to the solid particles within the regeneration vessel.

  
In these embodiments, the fluidizing gas in the dense zone of the regenerator can have a velocity, for example between about 6.1 and 121.92 cm / second, so

  
  <EMI ID = 92.1>

  
tion used to fluidize the dense bed contains free or molecular oxygen, and the oxygen is charged to the generator in an amount somewhat in excess of that required for the complete combustion of the coke (carbon and hydrogen ) carbon dioxide and water vapor. The amount of oxygen in excess of that required for complete combustion of the coke may

  
  <EMI ID = 93.1>

  
Theoretical stoichiometric amount of oxygen required for the complete combustion of the coke, but advantageously it does not need to be greater than about 10%. For example, when using air as the regeneration gas, an excess of air of
10% provides only about 2% volume of oxygen in the effluent spent gas stream. Advantageously, the concentration of free or molecular oxygen and of carbon monoxide at any point within the regenerator is kept outside the explosive range under these conditions, preferably the concentration of carbon monoxide is below the explosive range in these conditions, to eliminate any risk of detonation.

  
The regeneration gas, in addition to molecular or free oxygen, may contain inert gases or diluents such as nitrogen, water vapor, etc. Frequently the oxygen concentration in the regeneration gas upon entering the gas. the regenerator is between about 2 and 30% by volume, preferably about 5 to 20% by volume. Since air is conventionally used as the source of oxygen, a major proportion of the inert gas may be nitrogen The inert gas can be used to dissipate excess heat from the combustion of coke on the catalyst.

   A source of hot inert gas is the effluent from the regenerator and a portion of this gas can be recycled to the regenerator and, for example, combined with a sufficient supply of air or any other gas containing air. oxygen, including substantially pure oxygen, to ensure the desired oxygen content. Therefore, the recycle gas can be used in direct heat exchange to increase the temperature of the regeneration gas to provide further thermal savings in the system.

  
Solid particles within the dilute phase can be partially transported to the separation zone, usually having cyclone separators in a plurality of stages, from where the solid particles can be returned directly by hollow rods plunging into the zone. dense bed, and the spent regeneration and combustion gases are collected in a full (plenum) and finally discharged to properly recover the thermal energy they contain.

   Methods of recovering heat from the flue gases include steam regeneration, stripping of spent catalyst, indirect heat exchange with various refining streams, such as feed to the particular transformation process, and use in various drying or evaporating devices. With the accompanying plate of drawings, Figures 1 and 2 provide elevational views, partially in section, of embodiments of the apparatus suitable for catalyst regeneration according to embodiments of the process of the present invention involving the patent regeneration scheme

  
  <EMI ID = 94.1>

  
be applied with advantages in b in existing installations for cracking petroleum hydrocarbons, in particular

  
fluidized catalytic cracking installations with

  
a variety of spatial arrangements of cracked sections,

  
skinning and regeneration.

  
Figure 1 illustrates one of these embodiments of the present invention using a bottom inlet of the spent catalyst, stripped, passing from the cracking reactor.
(not shown) to the regenerator. The solid particles of the spent catalyst impregnated with the metallic initiating agent and a metallic reagent coming from the stripping zone associated with the outlet of the catalyst from the reactor, enter through the bottom of the regeneration vessel 1. The solid particles flow upwards through inlet pipes 2 and 3 and

  
  <EMI ID = 95.1>

  
The dense phase bed is maintained in the lower section 6 of the

  
  <EMI ID = 96.1>

  
phase face 7. Solid particles in the dense phase bed are fluidized by the flow of combustion air through.

  
  <EMI ID = 97.1>

  
air 11. Practically balanced airflow patterns in the regeneration zone can be achieved by using

  
  <EMI ID = 98.1>

  
  <EMI ID = 99.1>

  
  <EMI ID = 100.1>

  
higher temperatures by temporarily burning torch oil, for example decanted oil, in the bed. Torch oil can be added by passing through a pipe 12, a valve 13 and a pipe 14 which ends in a nozzle located

  
above the air ring 11. Fluidizing air velocities t &#65533; ans continuously carry a certain amount of solid particles upward into the dilute phase zone which occupies the portion.

  
  <EMI ID = 101.1>

  
above the phase interface 7. Coke combustion continues in the dilute phase zone and the largely exhausted combustion gas with the solid particles entrained in the first stage of cyclone separators 20 and 21 is removed. Most of the solid particles are separated in the first stage of cyclones and discharged downward through hollow dip rods 22 and 23 into the dense phase zone. The remaining gases and solid particles pass through lines 24 and 25 between the stages of cyclones to the second stage of cyclone separators.

  
  <EMI ID = 102.1>

  
duelles are separated and pass downward through dip rods 28 and 29 into the dense phase bed. Substantially all of the spent combustion gas passes through lines 20 and 31 into a chamber 32 and finally is discharged from the regenerator vessel through a line 33. This effluent can be suitably subjected to heat exchange, not shown, with a refining stream or for the production of process steam. The solid particles of the regenerated catalyst are withdrawn from the dense bed through lines 34 and 35 fitted with collecting heads 36 and 37 for the return to the reactor.

  
cracking.

  
Although the supply of air for combustion ensures an excess of oxygen over the amount required to effect complete combustion of the coke on the catalyst particles into water vapor and carbon dioxide, combustion of the coke may not be complete in the dense phase bed according to one of the embodiments of the present invention which applies the regeneration scheme of US Pat. No. 3,909,392. In this situation, the combustion gases rising from the dense bed zone therefore contain a significant amount of carbon monoxide as well as carbon dioxide and oxygen. The coke remaining on the catalyst and the carbon monoxide are essentially burnt off in the dilute phase zone with the development of additional heat.

   When carbon monoxide burns in the dilute phase, a zone of elevated temperature is usually present within most of the zone.

  
in dilute phase and particularly near the point indicated by X and which can be easily examined, by a window, not shown, in this horizontal plane. The regulation of the regeneration temperature within the dilute phase zone is effected in part by absorption of heat by the mass of the solid particles, that is to say transported upwards by the rise of the neck.

  
  <EMI ID = 103.1>

  
exhaust 40 from the dense bed, and a distributor head
41 where a rain or fountain of solid particles disperses in the dilute phase zone. The solid particles can be directed with air, water vapor or other inert gas entering through a line 42, a valve 43 and an injection tube.

  
  <EMI ID = 104.1>

  
of the exhaust pipe 40. It is also possible to regulate an excessive temperature in the top section of the regenerator.

  
  <EMI ID = 105.1>

  
  <EMI ID = 106.1> bre- by the steam supplied by a pipe 50, a valve 51 and

  
  <EMI ID = 107.1>

  
presser 32. Further cooling, if desired, can be provided by the use of a water spray, not shown, which can advantageously be directed into the region.

  
  <EMI ID = 108.1>

  
low temperatures promote the formation of stable compounds containing metal and sulfur in the regeneration zone.

  
Figure 2 illustrates another embodiment of the present invention, using the regeneration scheme of US Patent No. 3,909,392 with side entry of solid particles of spent, stripped catalyst and agent. metallic initiation and metallic reagent, from the cracking reactor to the regenerator. The solid particles of spent catalyst impregnated with the metallic initiating agent and metallic reagent enter the regeneration vessel 101, flow out <EMI ID = 109.1>

  
  <EMI ID = 110.1>

  
dense phase, maintained in a bottom section 106 a short distance below the phase interface 107. Fluidization of the solid particles is effected by air for combustion passing through line 108, valve 109, and line 110 to an air ring 111. Additional air rings, not shown, can be used, if desired, to further balance the air flow patterns in the regeneration zones. As depicted in Figure 1, the combustion of the coke on the spent catalyst particles is initiated in the dense phase zone where temperatures as high as desired can be achieved by temporary combustion of a stream of torch oil in the area. This torch oil can be added by a con-

  
  <EMI ID = 111.1> a nozzle.

  
The velocity of the fluidizing air can be regulated to continuously drive up the solid particles, in order to absorb heat in the dilute phase zone

  
which occupies the upper section 115 of the regenerator vessel, i.e. the section which is above the phase interface
107. The combustion of the coke as well as that of the carbon monoxide can continue in the dilute phase zone and the combustion gas, largely depleted together with the entrained portion of the solid particles, is withdrawn into cyclone separators of the. first stage 120 and 121. In these first stage cyclones, most of these solid particles are separated and discharged downward by hollow plunging rods 122 and 123 in the dense phase zone.

   The remaining gases and solid particles then pass through lines 124 and 125 between the cyclone stages to cyclone separators 126 and 127 of the second stage or. virtually all of the remaining solid particles are separated and pass downward through hollow plunging rods

  
128 and 129 in the dense phase bed. The substantially exhausted combustion gas then passes through lines 130 and 131 into

  
  <EMI ID = 112.1>

  
generator via a line 133. Solid particles are removed

  
of the regenerated catalyst from the dense bed, passing through

  
pipes 134 and 135 provided with collecting heads 136 and 137 'for the return to the reactor. catalytic cracking.

  
As described for the embodiment

  
in Figure 1, carbon monoxide burns in the dilute phase,

  
  <EMI ID = 113.1>

  
  <EMI ID = 114.1>

  
indicated by X. The regulation of the regeneration temperature in the diluted zone is effected largely by absorption of heat by the mass of solid particles carried upwards by the rising flow of the combustion gases. The temperatures in the vicinity of the booster, cyclone and connecting pipes can be lowered if desired with supplied steam.

  
  <EMI ID = 115.1>

  
steam ring 153 which surrounds chamber 132. Likewise, water spray devices, not shown, can be used.

  
In other particularly preferred embodiments of the present invention, the apparatus shown in FIGS. 1 or 2 is used with a significant modification of the operating parameters, compared to the embodiments previously described. In these forms of implementation,

  
the speed of the gas and the arrival of the solid particles are controlled so that a practically complete combustion of the coke and the carbon monoxide is completed within the dense phase and that the heat

  
  <EMI ID = 116.1>

  
In all these forms of implementation, the stabilization of the combustion reaction is particularly reinforced.

  
by the use of the metallic initiating agent and the regenerator is therefore able to operate at a lower temperature or to burn larger quantities of carbon monoxide and thus regenerate a larger quantity of cracking catalyst

  
at the same temperature. These low temperatures promote the formation of stable compounds containing metal and sulfur in

  
the regenerator.

  
When this system operates in accordance with one of the forms of the two embodiments previously described, the recovery of the heat released by the practically total combustion of the coke and of the carbon monoxide takes place by absorption.

  
in the solid particles, in both phases and the return of the solid particles in the dense phase also serves to ensure the maintenance of this appropriate high temperature within the dense phase zone. The returned solid particles can carry additional heat which serves to raise the temperature of the dense phase zone to a temperature which promotes combustion of the additional positions of coke deposits, so that combustion of the final portions of coke is virtually complete. When the system is operating so that practically

  
all combustion is completed in the dense catalyst phase, heat is dispersed within this phase as it is absorbed by the fluidized solid particles and the final portions of coke are burned. Consequently, in all these embodiments, the solid particles of regenerated catalyst returning from the regenerator to the reactor

  
crackers suitably contain from about 0.01 to in-

  
  <EMI ID = 117.1>

  
preferably about 0.01 to about 0.03% weight of carbon or coke on the catalyst and can be removed from the regenerator at a favorable temperature for use in the cracking reactor.

  
A remarkable advantage of these embodiments of the invention is that a regenerated catalyst is provided which generally has improved activity and selectivity characteristics, more closely similar to those of the fresh transformation catalyst, particularly during transformations carried out with very short contact times

  
  <EMI ID = 118.1>

  
catalyst containing a sieve and their selectivity to transform hydrocarbon feedstocks into desired products are both very markedly modified in a favorable direction by further removal of residual carbon or coke on the catalyst during regeneration. Especially preferred is the low coke content on the catalyst regenerated with fluidized bed cracking catalysts containing crystalline, catalytically active aluminosilicates. As a result, larger conversions of the feed and higher yields of the desired transformation products are achieved. The metallic initiating agent in this process helps stabilize the regulation of the regenerator, by regulating the oxidation of carbon monoxide.

   In addition, the risk of the extinction of the oxidation of carbon monoxide by a drop in temperature, an increase in the speed of the gas which can cause

  
blowing or a decrease in the carbon monoxide content,

  
because the oxidation of carbon monoxide is favored. The metallic initiating agent also results in lower regeneration temperatures and thus promotes the formation of a stable compound containing metal and sulfur in the regeneration zone.

  
  <EMI ID = 119.1>

  
lower zone with dense phase and upper zone with dilute phase;

  
  <EMI ID = 120.1>

  
in carbon dioxide can be made to a significant extent, often

  
  <EMI ID = 121.1>

  
until completion in the dense phase of the regenerator. The oxidation of carbon monoxide to carbon dioxide in the dense phase provides heat to help support the combustion of coke deposits from the fluidized catalyst. In addition, since a large portion of carbon monoxide is oxidized in the dense phase, a lesser amount of carbon monoxide is present for combustion in the upper phase of the fluidized catalyst in the regenerator, and thus one can significantly decrease or avoid "afterburning" and high temperatures due to excessive uncontrolled combustion of carbon monoxide in the upper portion of the regenerator, which can adversely affect the materials used to build the reactor, the gas stacks

  
of waste flue, collectors for possible particulate matter in the waste gas, for example in cyclones and which can compromise the activity of the catalyst.

  
Solid particles containing the regenerated catalyst particles with unusually low residual coke content are collected from the dense phase and or passed at substantially dense bed temperature through a line to the cracking reactor for contact with. a new one

  
hydrocarbon feed or a mixture with recycled hydrocarbon fractions. Since the favored oxidation of carbon monoxide from the combustion of coke deposits on the catalyst can occur to a large extent in the dense phase

  
and occurs according to the preferred embodiments, substantially all in the dense phase, the regenerated catalyst can be returned to the cracking reactor at a much higher temperature as well as with a higher activity than what was happening up to present in conventional operations.

  
Many fluidized bed cracking plants operate on a primary "thermal equilibrium", dependent on the combustion of coke for the release of heat required by the process. These installations, however, have not been able to fully utilize the advantages of cracking catalysts, in particular of zeolite type catalysts, which can be expected.

  
  <EMI ID = 122.1>

  
  <EMI ID = 123.1>

  
oil can be extremely short. The type of operation which ensures a large transformation coupled with a high selectivity, favors a low ratio between the catalyst and the oil in the lift reactor, which results in a less quantity of available coke capable of generating heat by combustion in the regenerator. Consequently, an external heat source, such as a feed preheating furnace, must frequently be added to increase the temperature of the catalyst or, alternatively, the installation must operate at a new lower feed temperature. These undesirable characteristics can be avoided or reduced by the process according to the invention which allows

  
efficient recovery of additional heat by the solid particles, for transport to the riser reactor. The heat of combustion of coke in typical operations is about 6666 calorie-grams / gram. The process according to the invention can increase the heat available by combustion

  
coke up to about 9,445 calorie-grams / gram or more.

  
This higher heat of combustion tends to raise the temperature of the regenerator, lower the rate of coke on the regenerated catalyst and lower the rate of circulation of the solid particles while ensuring improved yields for a lower rate.

  
of given transformation.

  
EXAMPLE 1.-

  
200 g of commercially available calcined molecular sieve type cracking catalyst were impregnated in equi.

  
  <EMI ID = 124.1>

  
flax type Y, and subjected to ion exchange with hydrogen and rare earth ions, containing 30% by weight of alumina, with 3.90 g

  
  <EMI ID = 125.1>

  
  <EMI ID = 126.1>

  
the range from 20 to 75 microns. The impregnated catalyst particles were collected and dried at 122 [deg.] C, followed by calcination for 3 hours at 677 [deg.] C. The resulting catalyst contains 0.3% by weight of manganese.

  
EXAMPLE 2. -

  
The procedure of Example 1 is repeated, except that 1.265 g of uranyl nitrate dissolved in 210 ml of water is used as the impregnation solution. The impregnated catalyst was dried at 122 [deg.] C and then calcined for 3 hours at 677 [deg.] C. The cata-

  
  <EMI ID = 127.1>

  
EXAMPLE 3. -

  
  <EMI ID = 128.1>

  
The procedure of Example 1 is repeated, except that 0.82 g of ammonium metatungstate dissolved in 210 ml of water is used as the impregnation solution. The catalyst is dried

  
at 122 [deg.] C then calcined for 3 hours at 677 [deg.] C. The catalyst re-

  
  <EMI ID = 129.1>

  
as an impregnation solution. The catalyst is dried and calcined as in Example 1 and contains 0.3% cerium.

  
EXAMPLE 5.-

  
The process of Example 1 is repeated except that 2.73 g of zinc nitrate hexahydrate in 200 ml of water is used.

  
as an impregnation solution. The catalyst is dried and calcined as in Example 1 and it contains 0.3% by weight of zinc. EXAMPLE 6.-

  
We repeat the process of example 1, except that we <EMI ID = 130.1>

  
EXAMPLE 7.-. We repeat the process of example 1 except that we <EMI ID = 131.1>

  
aqueous as an impregnation solution. We dry it; catalyst impregnated at 122 [deg.] C for 3 hours and then calcined at 677 [deg.] C during

  
  <EMI ID = 132.1>

  
molybdenum.

  
EXAMPLE 8. -

  
We repeat the process of example 1, except that we

  
  <EMI ID = 133.1>

  
with water, as an impregnation solution. The solution is heated until the titanium salt is completely dissolved.

  
The catalyst was dried at 122 [deg.] C and then calcined for 3 hours at 677 [deg.] C. The resulting catalyst contains 0.3% by weight of titanium.

  
EXAMPLE 9.-

  
The procedure of Example 1 is repeated except that 1.2 g of chromic oxide dissolved in 200 ml of water are used as the impregnation solution. The impregnated catalyst was dried for 3 hours at 122 [deg.] C and then calcined for 3 hours at

  
  <EMI ID = 134.1>

  
EXAMPLE 10.-

  
The procedure of Example 1 is repeated, except that 2.12 g of zirconyl chloride dissolved in 200 ml of water are used as the impregnation solution. The im- catalyst is dried.

  
  <EMI ID = 135.1>

  
200 ml of water as an impregnation solution. We dry it

  
  <EMI ID = 136.1>

  
  <EMI ID = 137.1>

  
EXAMPLE 12.-

  
We repeat the process of example 11 except that we

  
  <EMI ID = 138.1>

  
210 ml of water as an impregnation solution. The resulting catalyst contains 0.1% manganese.

  
EXAMPLE 13.-

  
50 g are impregnated with an industrially available catalytic cracking catalyst, in equilibrium, which has been calcined and is example of coke, and which contains 2 to 4% of a molecular sieve.

  
  <EMI ID = 139.1>

  
Magnesium nitrate trihydrate in 50 ml of water, sufficient to completely wet the cracking catalyst. The wet catalyst was then dried for 3 hours at 122 [deg.] C and then calcined at 538 [deg.] C for 3 hours. The catalyst contains 1% by weight of magnesium.

  
EXAMPLE 14.-

  
The process of Example 13 is repeated except that half the amount of magnesium nitrate is used for furnace.

  
  <EMI ID = 140.1>

  
EXAMPLE 15. -

  
36.24 kg are impregnated with an industrially available cracking catalyst in equilibrium, which has been calcined and which is free of. coke and contains 3.8% by weight molecular sieve in a silica-alumina matrix, in three batches with 1.90 kg

  
of magnesium nitrate dissolved in 12 liters of water, just enough to fill the pore volume of the catalyst. We dry it

  
  <EMI ID = 141.1>

  
catalyst.

  
EXAMPLE 16. -

  
100 mg of chloroplatinic acid are dissolved in 1 liter of water and 18 ml of this solution are diluted with a quantity of water sufficient to wet 300 g of an industrially available equilibrium cracking catalyst which has been withdrawn. of an industrial plant and then calcined at 538 [deg.] C for

  
  <EMI ID = 142.1>

  
calcines at 538 [deg.] C for 3 hours. The catalyst contains 6 parts per million by weight of platinum.

  
EXAMPLE 17. -

  
95 g of an industrially available alumina are wetted with a solution of 3.22 g of ammonium vanadate and 5 g of oxalic acid in 95 ml of water and then dried at 122 [deg.] C for 3 hours. and calcined at 538 [deg.] C for 3 hours. This alumina impregnated with vanadium is then wetted with a solution of 9.3 g of copper nitrate in 95 ml of water. This wet alumina was dried at 122 [deg.] C for 3 hours and calcined at 538 [deg.] C for

  
  <EMI ID = 143.1>

  
by weight of copper.

  
EXAMPLE 18.-

  
10 g of a solution of 6.9 g of lubricating oil adjuvant which contains 9.2% by weight of

  
  <EMI ID = 144.1>

  
magnesium bonate and polypropyl-benzene sulphonate of magnesium

  
  <EMI ID = 145.1>

  
in a laboratory-scale cracking installation, having

  
a fluidized bed of 220 g of an industrial cracking catalyst

  
  <EMI ID = 146.1>

  
molecular weight and about 0.6% by weight sodium and withdrawn from an industrial fluidized bed catalytic cracking plant and then calcined. The recycle oil is cracked at 372 [deg.] C

  
  <EMI ID = 147.1> for 10 minutes at 677 [deg.] C, the catalyst bed is cooled to
372 [deg.] C and the cracking-purging-regeneration cycle is repeated until the magnesium, zinc and phosphorus contents of the catalyst reach levels of 110, 703 and 59 parts per million, respectively. Zinc and phosphorus are inherently present.

  
EXAMPLE 19.-

  
The process of Example 18 is repeated, except that the cracking-purging-regeneration cycle is repeated with 10 g of a solution containing 6.5 g of oil and 3.5 g of oil adjuvant. read-

  
  <EMI ID = 148.1>

  
EXAMPLE 20. -

  
The procedure of Example 19 is repeated, except that an industrially available cracking catalyst is used.

  
  <EMI ID = 149.1>

  
in a silica-alumina matrix and which has also been withdrawn from an industrial fluidized and calcined catalytic cracking installation, and the cracking-purging-regeneration cycle is repeated until the magnesium, zinc and phosphorus from the catalyst reach 4600, 304 and 1136 parts per million, respectively.

  
EXAMPLE 21. -

  
Lubricating oil adjuvant is used in an amount of 7.3 g and containing 8.2% by weight of magnesium, distributed in the form of magnesium carbonate, magnesium hydroxide and magnesium polypropylbenzene sulfonate and a volume sufficient xylene to wet 2000 g of an industrially available cracking catalyst in equilibrium which has been withdrawn from an industrial catalytic cracking plant and calcined, and which contains 2.5% by weight of molecular sieve in a matrix of

  
  <EMI ID = 150.1>

  
for 20 hours. The catalyst contains 3000 parts per million of magnesium.

  
EXAMPLES 22 to 27.-

  
A laboratory scale regeneration plant was used to investigate the ability of a number of the impregnated catalysts of Examples 1 to 21 to provide lower emissions of carbon monoxide in the regeneration zone flue gases. A combustion gas is passed from

  
  <EMI ID = 151.1>

  
and water vapor each, and 88% by volume of nitrogen at a rate of

  
  <EMI ID = 152.1>

  
  <EMI ID = 153.1>

  
metal, which is held in a glass regenerator surrounded by a furnace to ensure the desired regeneration temperature of 6-9 [deg.] C. The temperature of the catalyst is measured by thermocouples. A cyclone is used to separate the catalyst entrained in the gas leaving the regenerator and return the catalyst to the catalyst bed. The length of time the regenerator operates

  
  <EMI ID = 154.1>

  
approximately 90 minutes so as to allow sufficient time to establish the oxidation state of the metal on the catalyst in an actual operation in an industrial fluidized catalytic cracking installation.

  
The gas leaving the regenerator is analyzed by gas chromatography for oxygen, nitrogen, carbon monoxide and

  
carbon dioxide. The quantity of carbon monoxide converted is determined by the difference between the carbon monoxide contents of a new mixture of artificial gas and that of the gas leaving the regenerator.

  
In Examples 22 to 26, the catalysts

  
  <EMI ID = 155.1>

  
in volume of carbon monoxide transformed is respectively 65,

  
  <EMI ID = 156.1>

  
Several of the foregoing catalysts are investigated according to standard uniform methods of experience, applied in industry, in a microfluidized catalytic plant, to determine the desired selectivity of catalytic cracking. As the base, in Example 28, the unimpregnated cracking catalyst used in Example 1 has a relative micro-activity of

  
  <EMI ID = 157.1>

  
and methane in mole percentage of 0.64. In Example 29, the impregnated catalyst prepared in Example 1 is used, and it includes

  
  <EMI ID = 158.1>

  
1.1 and a molar percentage ratio between hydrogen and

  
methane from about 1.1 to 1.2. In Example 30, the impregnated catalyst prepared in Example 4 is used and it demonstrates a relative micro-activity of 150, a coke factor of 1.1 and a

  
&#65533; &#65533;, molar percentage ratio between hydrogen and methane

  
  <EMI ID = 159.1>

  
EXAMPLES 32 to 38.-

  
We repeat the process. from examples 22 to 27, to this

  
  <EMI ID = 160.1>

  
particle size is 5 microns and finer, mixed with the unimpregnated catalyst used in Example 1, instead of impregnated catalysts. Powdered metal oxides ,. their quantities and the percentage by volume of carbon monoxide converted into carbon dioxide in Examples 32 to 35 as well as in Comparative Example 36, which does not use metal oxide, all other conditions being otherwise identical, are shown in Table I. Similar data is also shown in Table 1 for Example 37 and its Comparative Example 38, which do not use metal oxide, all other conditions being otherwise identical.

TABLE I

  

  <EMI ID = 161.1>


  
  <EMI ID = 162.1>

  
after preparing the artificial combustion gas with 1500

  
  <EMI ID = 163.1>

  
by volume of oxygen and water vapor each, in nitrogen at

  
677 [deg.] C &#65533; that it is passed through the regenerator at the rate of

  
  <EMI ID = 164.1>

  
  <EMI ID = 165.1>

  
Sulfur dioxide from the effluent gas. Comparative tests were carried out using the unimpregnated catalyst used in Example 16 and the impregnated catalyst used in Example 16. Example 39 involves the unimpregnated catalyst while Example 40 involves the impregnated catalyst. The percentages by volume of sulfur dioxide removed from the combustion gas of the regeneration zone are given as a function of the passage of time after the start of the experiment, in Table II. The volume percentage decreases with time as the surface of the catalyst becomes saturated. AT

  
  <EMI ID = 166.1>

  
the catalyst is 55 parts per million before the experiment and 368 parts per million afterwards, which corresponds to the re-

  
  <EMI ID = 167.1>

  
from regeneration gas. In Example 40, the sulfur content in the form of soluble sulphate on the catalyst is 111 parts per million before the experiment and 733 parts per million after, which corresponds to a recovery on the catalyst of 91% by weight. sulfur removed from the regeneration zone.

  

  <EMI ID = 168.1>


  

  <EMI ID = 169.1>
 

  
EXAMPLES 41 and 42.-

  
  <EMI ID = 170.1>

  
comparative tests using mixtures of molecular sieve cracking catalyst and different amounts of alumina impregnated with vanadium and copper, produced in Example 17. A

  
  <EMI ID = 171.1>

  
cular and which was withdrawn from an industrial catalytic cracking installation in a fluidized bed and calcined at 538 [deg.] C for

  
5 hours. The flow rate of artificial combustion gas is

  
  <EMI ID = 172.1>

  
industrial cracking lyser in equilibrium, calcined used in Example 41. The flow rate of artificial combustion gas is

  
  <EMI ID = 173.1>

  
sulfur dioxide removed from the combustion gas for the examples

  
41 and 42 are shown in Table II.

  
EXAMPLES 43 to 47.-

  
The procedure of Examples 39 and 40 was repeated using a regeneration temperature of 677 [deg.] C. Example 43 is a comparative run applying a flow rate of the artificial combustion gas mixture of 1084 ml per minute and the unimpregnated equilibrium catalyst used in Examples 18 and 19, while Examples 44 and 45 involve the impregnated catalyst produced at

  
Examples 18 and 19, respectively, and artificial combustion gas flow rates of 989 and 1014 ml per minute, respectively.

  
  <EMI ID = 174.1>

  
impregnated used in Examples 20, 41, and 42 and a flow rate of the mixture of artificial combustion gas of 891 ml per minute.

  
The percentages by volume of sulfur dioxide removed from the gas

  
combustion for Examples 43 to 47 are shown in Table II.

  
EXAMPLES 48 to 50. -

  
Synthetic cracking tests are carried out on a

  
  <EMI ID = 175.1>

  
of sulfur in the form of organic sulfur compounds. In

  
comparative cracking tests with constant cracking severity in Examples 48 to 50, with the unimpregnated, calcined equilibrium catalyst used in Example 13 and with the impregnated catalyst produced in Examples 13 and 14 respectively,

  
the amounts of sulfur dioxide released from the stripped catalysts, deactivated after the next regeneration, are measured and calculated in parts per million by weight of sulfur on the catalyst.

  
The sulfur strippable in Example 48 of the non-magnesium catalyst is 134 parts per million by volume. The eliminable sulfur

  
  <EMI ID = 176.1>

  
sium is 52 parts per million, a decrease of 61%.

  
The sulfur which can be removed in Example 50 from the catalyst containing

  
  <EMI ID = 177.1>

  
EXAMPLES 51 and 52.-

  
Comparative tests are carried out involving the cracking of a gas oil containing sulfur by weight in a continuous cracking-regeneration plant of the type described in

  
  <EMI ID = 178.1>

  
implemented in Example 21 and the impregnated catalyst produced in Example 21. Example 51 involves the unimpregnated catalyst while Example 52 involves the impregnated catalyst. The operating conditions and the composition of the combustion gas. regenerator are shown in Table III.

  
EXAMPLES 53 and 54.-

  
Fluidized bed cracking tests are carried out in a cyclic installation on a semi-industrial scale with a load

  
  <EMI ID = 179.1>

  
using the unimpregnated catalyst used in Example 15 and the impregnated catalyst produced in Example 15. Examples 53 and 54 involve the unimpregnated and impregnated catalysts, respectively. The operating conditions and the composition of the combustion gas from the regeneration zone are shown in Table III. The impregnated catalyst leads to a decrease in
57.5% sulfur dioxide emission in the regenerator combustion gas. Processing and product yields are essentially the same for each catalyst. EXAMPLES 55 and 56. -

  
  <EMI ID = 180.1>

  
the sulfur content is 1.67% by weight in an industrial fluidized bed catalytic cracking element having a riser reaction. Conventional regeneration is applied. An industrial equilibrium type cracking catalyst is used.

  
  <EMI ID = 181.1>

  
second charge of diesel oil with a sulfur content of 1.68% by weight, in the same industrial installation, by applying the same regeneration scheme and the same cracking catalyst, but in addition the catalyst is impregnated with magnesium and zinc. Magnesium and zinc are deposited on the catalyst by introducing low concentrations of magnesium sulfonate and zinc dialkyl dithiophosphate into the reaction zone, in the form of a lubricating oil adjuvant in the feed. After several additions in this way, levels of 0.3% magnesium <EMI ID = 182.1>

  
The operating conditions and the composition of the gases

  
  <EMI ID = 183.1>

  
EXAMPLES 57 and 58.-

  
A charge of gas oil having a sulfur content of 0.26% by weight is cracked in an industrial fluidized bed catalytic cracking plant having a riser reactor and applying conventional regeneration. In Example 58, an industrial equilibrium fluidized cracking catalyst of molecular sieve type containing 2.5% by weight of molecular sieve and 1.01% by weight of sodium is used. The sodium is deposited on the catalyst by introduction with the charge of an aqueous solution of sodium chloride. Comparative Example 57 involves cracking a gas oil with a sulfur content of

  
0.28% in the presence of the same catalyst as that of Example 58 but not impregnated with sodium, all other conditions besides being the same. The operating conditions and the composition of the combustion gases from the regeneration zone are shown in Table III.

  
EXAMPLES 59 and 60.-

  
In example 59, a charge of diesel oil is cracked,

  
the sulfur content is 0.81% in an industrial fluidized bed catalytic cracking plant having a riser reactor and a regenerator of the type shown in Figure 2. The regeneration is carried out in accordance with the regeneration scheme of

  
  <EMI ID = 184.1>

  
Molecular sieve type equilibrium fluidized bed containing 4.1% by weight molecular sieve, 0.64% by weight of iron, 56 parts per million of copper and 0.22% by weight of sodium. In Example 60, a second charge of gas oil with a sulfur content of 1.14% by weight is cracked in the same industrial installation using the same regeneration scheme and an industrial fluidized bed cracking catalyst in sieve type balance

  
  <EMI ID = 185.1>

  
by weight of iron, 34 parts per million of copper, 0.22% by weight of sodium and 0.09 parts per million of platinum. There are 270 tonnes of this catalyst in the installation and the platinum is deposited on the catalyst by introducing into the reaction zone with the feed, a solution of platinum acetylacetonate in benzene. A total of 20 g of platinum metal is introduced with an average rate of 3 g of platinum metal per day. For both catalysts sodium is inherently present in the catalyst and copper and iron are introduced into the cracking process cycle as components of the feed. The operating conditions and the composition of the combustion gases from the regeneration zone are shown in Table III.

  
The results indicate that the addition of platinum to the cracking catalyst produces lower emissions of sulfur oxides, even when the hydrocarbon feed contains higher amounts of sulfur. In addition, the emission of carbon dioxide

  
  <EMI ID = 186.1>

  
molars which are characteristic of conventional regeneration in the absence of a platinum-initiated catalyst. The increase of

  
the amount of carbon monoxide in the combustion gas of the regeneration zone, when using a carbon dioxide catalyst

  
Platinum-primed cracking is the consequence of a higher rate of combustion air in this case. Temperature

  
  <EMI ID = 187.1>

  
  <EMI ID = 188.1>

  
at the entry of the cyclone, the increase in the temperature of the bed,

  
  <EMI ID = 189.1>

  
and that at the inlet of the cyclone, when using the platinum-initiated cracking catalyst, indicate a significant increase in the extent of combustion of carbon monoxide in the dense bed.

  

  <EMI ID = 190.1>


  

  <EMI ID = 191.1>



    

Claims (1)

1.- Improvement in a cyclic process for catalytic cracking in a fluidized bed of a hydrocarbon feed containing organic sulfur compounds in which (1) this feed is subjected to cracking in a reaction zone with fluidized solid particles of a molecular sieve type cracking catalyst, (2) separating the catalyst particles which have been deactivated by carbonaceous deposits containing sulfur from the reaction zone effluent, and transported to a stripping zone in which volatile deposits are removed from the deactivated catalyst by contact with stripping gas, (3) the stripped catalyst particles are separated of the effluent from the stripping area and transported in a regeneration zone and carbonaceous deposits which cannot be removed and which contain sulfur on the stripped catalyst particles are regenerated by combustion with an oxygen-containing gas, and (4) the regenerated catalyst particles are separated effluent from the regeneration zone and recycled to the reaction zone; said method, to lower emissions of carbon monoxide and sulfur oxides in the effluent gas stream from the regeneration zone, being characterized (a) in that the cracking catalyst is circulated in the process cycle in combination with a metallic reagent which reacts with the sulfur oxides in the regeneration zone, this combination being formed by fluidizable solid particles, where the metallic reactant is present in an amount sufficient to lower the concentration of sulfur oxides in the effluent gas stream from the regeneration zone, and where the metallic reagent consists essentially by at least one free or combined metallic element which is chosen from the group consisting of sodium, magnesium, calcium, strontium, barium, scandium, titanium, chromium, molybdenum, manganese, iron, cobalt, nickel, anti-monk, copper, zinc, cadmium, lead, rare earth metals, their compounds and mixtures, (b) <EMI ID = 192.1> is carried out 649 [deg.] C, (c) the volatile deposits are stripped from the particles of the combination at temperature of about 455 to about 649 [deg.] C with a stripping gas which contains water vapor, where the proportion of steam to catalyst is from about 0.0005 to about 0.025 per unit time, (d) the particles of the combination are regenerated at a temperature of about 566 to about 788 [deg.] C in the presence of an agent which promotes the oxidation of the oxide carbon, which consists of at least one free or combined metallic element selected from the group consisting of elements of the 5th and 6th periods of Group VIII of the Periodic Table, vanadium, silver, rhenium, their compounds and mixtures thereof , and wherein the initiator is present in an amount sufficient to decrease the concentration of carbon monoxide and oxides sulfur in the effluent gas stream from the regeneration zone and (e) an effluent gas stream is withdrawn from the regeneration zone which contains molecular oxygen. <EMI ID = 193.1> that the initiating agent is chosen from the group consisting of ruthenium, rhodium, palladium, osmium, iridium, platinum and rhenium, their compounds and their mixtures, and where the amount of initiator is from about 0.1 parts per million to about 10 parts per million, calculated as a metal and based on the weight of the particles in the combination. 3. A method according to claim 2, characterized in that the initiating agent is chosen from the group consisting of platinum, palladium, their compounds and their mixtures. <EMI ID = 194.1> that the initiator is chosen from the group consisting of vanadium, its compounds and mixtures thereof, and where the amount of initiator is between about 10 parts per million and about 10% by weight calculated as as a metal and based on the particle weight of the suit. 5.- Method according to claim 1, characterized in that the metal reagent is chosen from the group consisting of sodium, magnesium, calcium, strontium, barium, chromium, manganese, copper, zinc, cadmium and rare earth metals, their compounds and mixtures. 6. A method according to claim 1, characterized in that the metal reagent is chosen from the group consisting of sodium, magnesium, manganese, copper, their compounds and their mixtures. 7.- Method according to claim 1, characterized in that the metal reagent is chosen from the group consisting of sodium, magnesium, calcium, strontium, barium, scandium, titanium, chromium, molybdenum , manganese, iron, cobalt, nickel, antimony, copper, zinc, cadmium, lead, rare earth metals and their oxides. <EMI ID = 195.1> that the metallic reagent is chosen from the group consisting of sodium, magnesium, manganese, copper and their oxides. <EMI ID = 196.1> that the effluent gas stream from the regeneration zone contains; at least 0.5% by volume molecular oxygen. 10. A method according to claim 1, characterized in that the particles of the combination consist of fluidizable particles of cracking catalyst of the molten sieve type. <EMI ID = 197.1> metallic reagent. 11. A method according to claim 10, characterized in that the particles which contain the metallic reagent are composed of a support on or in which the metallic reagent is incorporated and in which the support is chosen from the group consisting of catalysts. crackers and solids that are practically inert in cracking the. charge. 12. A method according to claim 11, characterized in that the support is chosen from the group consisting of silica, alumina and mixtures thereof. 13. A method according to claim 10, characterized in that the initiating agent is additionally incorporated into the particles which contain the metallic reagent. 14. A method according to claim 1, characterized in that the particles of the combination consist of particles of the molecular sieve type cracking catalyst in or on which the metallic reagent has been incorporated. 15. A method according to claim 14, characterized in that the initiating agent is further incorporated in or on the particles of the molecular sieve type cracking catalyst. 16. A process according to claim 15, characterized in that the amount of molecular sieve type cracking catalyst is from about 90 to about 99.995% by weight of the combination of catalyst, initiator and starter. metallic reagent. <EMI ID = 198.1> incorporating at least one of the metallic reactant and the initiating agent in the particles of the molecular sieve type cracking catalyst, by introducing into the process cycle at least one soluble compound or dispersible in water or in the oil of one or more metallic elements of the initiating agent or of the metallic reagent. <EMI ID = 199.1> whether the compound soluble or dispersible in water or in oil is chosen from the group consisting of metal diketonates, carbonyl metals, metallocenes, metal complexes of olefins of 2 to 20 carbon atoms, metal complexes of acetylene, metal complexes of alkyl- or aryl-phosphines and metal carboxylates of 1 to 20 carbon atoms. 19.- The method of claim 17, characterized in that the water or oil soluble or dispersible compound is platinum acetylacetonate. 20.- The method of claim 1, characterized in that the oxidation initiating agent is incorporated in or on a support and in that the support is selected from the group consisting of amorphous cracking catalysts and solids which are substantially inert in cracking the feed. 21.- The method of claim 20, characterized in that the support is chosen from the group consisting of silica, alumina and mixtures thereof. 22.- Method according to claim 1, characterized in that the initiating agent is locked in the regeneration zone. 23.- Process according to claim 1, characterized in that the particles of the combination are regenerated at a temperature of about 638 to about 733 [deg.] C. 24.- Method according to claim 1, characterized in What the initiating agent is is a fluidizable powder which circulates in the cycle of the catalytic cracking process. <EMI ID = 200.1> that the metallic reagent is mainly in physical association with the molecular sieve type cracking catalyst, and where the metallic reagent is selected from the group consisting of sodium, rare earth metals, their compounds and their mixtures and in which the oxidation initiator is chosen from the group consisting of elements of the 5th and 6th periods of group VIII of the Periodic Table, vanadium, silver, rhenium, their compounds and their mixtures. <EMI ID = 201.1> that the metallic reagent is an oxide of an element selected from the group consisting of sodium and rare earth metals.