CA1142118A

CA1142118A - Process for the preparation of gasoline

Info

Publication number: CA1142118A
Application number: CA000324241A
Authority: CA
Inventors: Robert H. Van Dongen; Jakob Van Klinken
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1978-05-30
Filing date: 1979-03-27
Publication date: 1983-03-01
Also published as: DE2921601C2; GB2023167A; JPS6320877B2; GB2023167B; IT7923055A0; FR2427375B1; DE2921601A1; IT1121519B; NL7805841A; FR2427375A1; JPS54156013A

Abstract

ABSTRACT

Process for the preparation of gasoline from a hydrocarbon mixture boiling above the gasoline range, which is cracked over a catalyst mixture containing components A and B. Component A is a crystalline aluminosilicate zeolite with a pore diameter of more than 9 .ANG.. Component B is a crystalline iron silicate.

Description

11~21~8 A process for the preparation of gasoline The ;nvention relates to a process for the preparstion of gasoline from a hydrocarbon mixture boiling above the gasoline range.
For the preparation o gasoline from hydrocarbon mixtures boiling above the gasoline range cata~yt;c cracking is used on a large scale. Gasoline preparation by catalytic cracking is effected by contact;ng the oil to be cracked at elevated temperature with a cracking catalyst and separating from the cracked product a frac-tion boiling in the gasoline range. Catalysts which containa crystalline aluminosilicate zeolite with a pore diameter of more than 9 A, have been found very suitable for use as cracking catalysts. In addition to hydrocarbons boiling in the gasoline range, the cracked product contain~ both 1~ hydrocarbons boiling below the gasoline range and hydro-carbons boiling above the gasoline range. From the pro-duct boiling below the gasoline range, wh;ch contains propene and butene, an additional amount of gasoline can be prepared by alkylation. With a view to the gasoline preparation the light product fraction is more useful according as the propene and butene contents of this fraction are higher. For the evaluation of a catalytic cracking process for gasoline preparation account should Z1~8 therefore be taken not only of the amount and quality of the cracked gasoline obtained in the process, but also of the amount and quality of the gasoline which can be prepared by alkylation of the propene and butene present ;n the light product fract;on. An attract;ve basis for compari.ng catalytic cracking processes for the preparation of gasoline is the total amount of gasoline (cracked gaso1ine + a],-kylation gasoline) and the octane nu~ber of this gasoline which can be obtained with the process.
The Applicant has carri.ed out an investigation con-cerning the preparation of gasoline by catalytic cracking of a hydrocarbon mixture boiling above the gasoline range using catal~sts which contain a crystalline alu~ino-silicate zeolite with a pore diameter of more than 9 ~.
It was found ehen that considerably better results can be obtained with this process by using a catalyst mixture which contains, in addition to the above-mentioned crys-talline aluminosilicate zeolite with wide pores, a crys-talline silicate with narrow pores, which s;licate is one of a class of compounds which has recently been iynthe-sized for the first time by the Applicant. In a comparison of the results obtained in a crackjng process carried out using a crystalline alum;.nosilicate zeolite wieh wide pores as the catalyst and the results obtained in a cracking process carried out using the above-mentioned catalyst mixture, it is found in the first place that w;,th the catalyst mixture a cracked gasoline with a higher octane nu~ber is obtained. Although this gain in octane number is obtained at the cost of a yield of cracked gasoline that is lower when the catalyst mixture is used, this lower yield of cracked gasoline is amply offset by the fact that with the catalyst mixture a light product fraction with a considerably higher content of propene and butene is obtained. In summary. it can be stated that using the catalyst mixture. the total amount of gaso~.ine ;s higher and that ! in addition, this gasoline has a higher octane number than when use is made of a catalyst which contains a crystalline aluminosilicate zeolite with a pore diameter of more than 9 ~, but in which no crystalline silicate with narrow pores is present. The novel crystalline si].icates which have a pore diameter of less than 9 ~ are characterized as follows:
(a) they are thermally stable up to temperatures above 600C, tb) after dehydration at 400 C in vacuum, they are capable of adsorbing ~ore than 3 %w water at 25 C and saturated water vapour pressure, and (c) in dehydrated form, they have the following overall composition, expressed in moles of the oxides, )2/n /a Fe23- b A12O3 c Ga203 7.
y(d SiO2. e GeO2), where R = one or more monovalent or bivalent cations, a 3 0.1, b ~ 0, c ~ O, a + b + c = 1, y ~10.
d ~0.1, e ~ , d + e = 1, and n = the valency of R.
For the sake of brevity the crystalline aluminosili-cate zeolite with a pore diameter of more than 9 ~ will 3 in this patent application further be referred to as catalyst component A and the crystalline silicate with narrow pores as catalyst component B.
The present patent application therefore relates ll~Zil8 to a process for the preparation of gasoline from a hydrocarbon mixture boiling above the gasoline range, in which a hydrocarbon mixture boiling above the gasoline range is cracked with use of a catalyst mixture containing components A and B, in which from the cracked product a fraction boiling in the gasoline range is separated, in which catalyst component A is a crystalline aluminosilicate zeolite with a pore diameter of more than 9 A, and in which catalyst component B is a crystalline silicate as defined hereinbefore.
In the process according to the invention use is made Or a catalyst mixture containing the catalyst components A and B. It is preferred that catalyst components A and B are present in the catalyst mixture in combination with a porous matrix, such as silica, alumina, zirconia or mixtures thereof.
Particular preference is given to catalyst mixtures of which 10-50 D~DW consists of catalyst components A and B and the rest of a porous matrix. Each of the catalyst components A and B may be combined separately with a porous matrix.
Catalyst components A and B may also be combined together with one porous matrix. The proportion in which catalyst components A and B are present in the catalyst mixture according to the invention may vary within wide limits.
Preference is given to catalyst mixtures in which components A and B are present in a weight ratio of from 10:1 to 1:3 and in particular from 2:1 to 1:1.
Catalyst component B is a crystalline silicate of a special class. In the process according to the invention it is preferred to use catalyst compo-nents B in which no gallium and germanium are present, in other words, sili-cates of which, in the above-mentioned overall composition, c and e are 0.
Such silicates are the subject of Netherlands patent application No. 76.13957 filed on December 16, 1976 by Shell Internationale Research Maatschappij B.V.
Further, it is preferred i~2118 to use catalyst components B of which, in the above-mentioned overall composition, a is greater than 0.5, preferably equal to 1. Catalyst components B in which no aluminium is present, in other words, silicates of which, in the above-mentioned overall composition, b is 0 are particularly preferred. It should be noted that in the catalyst components B, y is preferably less than 600, and in particular less than 300. Finally, it is preferred in the process according to the invention to use silicates as catalyst component B whose X-ray powder diffraction patter has, inter alia, the reflections g:iven in Table A of Netherlands patent application No. 761957.
The crystalline silicates which are used as catalyst component B in the process according to the invention, are usually prepared starting from an aqueous mixture which contains the following compounds in a certain ratlo: one or more compounds of an alkali metal, one or more compounds containing an organic cation or from which such a cation is formed during the preparation of the silicate, one or more iron compounds and, optionally, one or more alumium, gallium and/or germanium compounds. The preparation is carried out by maintaining the mixture at elevated temperature until the silicate has been formed and then separating the crystals of the silicate from the mother liquor. Before being used in the process according to the invention, the organic cations which have been intro-duced during the preparation, should be converted into hydrogen ions by calcin-ation. It is preferred to use in the process a catalyst mixture whose alkali metal content is less than 1 %w, and in particular less than 0.05 %w.
In the process according to the invention catalyst components A
can be the usual crystalline aluminosilicate zeolites, known as cracking catalysts and having a pore diameter of more than 9 ~, such as natural and synthetic 11'~2118 faujasite, both of the X and of the Y type, snd zeolite L.
The preferred mater;al is synthetic zeolite Y, in particulsr a synthetic zeolite Y in which ions of the rare-earth metals are present.
In ehe process accord;ng to the invention gasoline is prepared by catalytic cracking. Catalytic cracking on a commercial scale is usually carried out in a continuous process with use of an apparfltus substantially consisting of a vertically mounted cracking reactor and a catalyst regenerator. Hot regenerated catalyst originating from the regenerator is suspended in the oil to be cracked and the mixture is conducted in upward direction through the cracking reactor. The deactivated catalyst is separated from the cracked product and, after stripping, transferred to the regenerator. The cracked product is separated into a light fraction, a gasoline fraction and one or more heavy fractions such as a light cycle oil, a heavy cycle oil and a slurry oil. To increase the gasoline yield one or more of the heavy product fractions may be recycled to the reaction section. To increase the gasoline yield the C3/C4 olefins present ;n the light fraction may be converted into gasoline by alkylation with isobutane.
The process according to the invention can very conveniently be carried out in the way described above. Suitable conditions for carrying out the catalytic cracking according to the invention are a temperature of from 200 to 700C, and preferably of from 450 to 650C, a pressure of from l to lO
bar, and preferably of from 1.5 to 7.5 bar aDd a space velocity of from 0.25 to 4 kg. kg l.h l, and preferably 30 of fro~ 0.5 to 2.5 k8. kg .h . Suitable hydrocarbon mixtures which may be used as the feed in the process according to the invention are atmospheric gas oils, vacuum gas oils, atmospheric distillation residues, vacuum distillation residues, shale o;ls, tar sand oils and oil ` -` 1.1~2118 obtained by coal extraction. It is preferred to use a gas oil as the feed.
In the process according to the invent;on it i9 preferret to add a hydrogen donor to the hydrocarbon mixture that ;s used as the feed. Suitable hydrogen donors are methane, methanol, mixtures of methanol and carbon monoxide, mixtures of carbon monoxide and water and paraf-fins and olefins with two to five carbon atoms per mole-cule. It is preferred to use methanol a-~ the hydrogen donor.
Methanol is preferably used in a weight rat;o of from O.Ol to 5 and in particular of from 0.05 to 0.30 based on the hydrocarbon oil used as the feed. The advantage of using a hydrogen donor in the process according to the invention is in the first place that a gasoline is obtained with a higher content of aro~atics and olefins and consequently of a higher quality than in the absence of a hydrogen donor.
The use of a hydrogen donor is further important, if a heavy fraction of the cracked product is to be used as fuel. When a hydrogen donor is used, a fuel is obta;ned with a lower sulphur content ! a higher hydrogen content, a higher naphthenes/aromatics ratio and a higher diaromatics/
benzothiophenes ratio. The use of a hydrogen donor in the process according to the invention is especislly preferable if the feed consists of metal-containing hydrocarbon o ls.
In addition, inter alia, to the above-mentioned way of carrying out the catalytic cracking process as this is done on a commercial scale, the present patent application also includes a number of attractive variants which wil]
be explained in more detail below.
Variant I
This variant relates to a process in which a gas oil is cracked in a first cracking zone at a temperature of at least 450C and in the presence of the catalyst mixture according to the invention, in which process the cracked 211~

product i9 separated in a first separation zone into a heavy cycle oil, a light cycle oil~ a heavy naphtha fraction and a product bolling below the sa;d heavy naphtha fraction, in which process the said heavy naphtha fract;on is cracked ;n a second cracki.ng zone at a temperature of from 450 to 550 C and in the presence of a fresh, regenerated catalyst mixture according to the invention, in wh;ch process the cracked product thus obta;ned is separated in a second separation zone into a light cycle oil, a fraction rich in aromatics and boiling in the gasoline range and a lighter product, in which process the said cycle oils are mixed, in which process the protuct boiling below the said heavy naphtha fraction which wa~ obtained in the cracking of the gas oil is mixed with the gasoline fraction and the lighter product which were obtained in the cracking of the heavy naphtha fraction, and in which process the latter mixture is separated into a fraction boiling in the gasoline range and a tower boiling gaseous fraction.
In this proce~s a resh, regenerated catalyst mixture according to the invention may be used successively in the cracking of the heavy naphtha, the cracking of the gas oil and the cracking of a straight-run naphtha, before the catalyst mixture is stripped and the stripped cata-lyst mixture is regenerated.
In this process it is further possible to use a fresh, regenerated catalyst mixture according to the invention both for cracking the heavy naphtha and or cracking the gas oil, and to pass the deactivated cata-lyst mixtures through a joint stripping zone prior to theregeneration.
Further, in this process the catalyst mixture that is used for cracking the gas oil may thereupon be used for cracking a straight-run naphtha, and the separat;on of the cracked products of the straight-run naphtha crack-ing and the gas oil cracking may be carried out in a jo-nt separation zone.
Finally, in this process the cracking of the straight-run naphtha may be carried out in the presence of theheavy cracked naphtha.
Variant II
This variant relates to a process in which a gas oil in contact with a catalyst mixture according to the invention is cracked into a product which contains a gas~
oline fraction, in which process at least part of the cracked product is contacted with catalyst component B
to increas~ its octane number by increasing the aromatics content or by alkylating the gasoline part of the pro-duct, in which process the cracked product is contacted exclusively with fresh catalyst component B, in which process deactivated catalyst mixture and deactivated catalyst component B are mixed, in which process the mixture is regenerated and in which process the cracking of the gas oil i9 carried out with the regenerated mixture.
In this process the cracking may be carried out in a first reaction zone and the aromatization or alkylation in a second reaction zone, in which the fresh catalyst component B is kept in this second reactor until it becomes deactivated.
Variant III
This variant relates to a process in which a regene-rated catalyst mixture in the form of a suspension is con-tacted at a temperature of from 540 to 760 C first with a hydrocarbon mixture boiling above the gasoline range in the lower part of a vertically mounted reactor and thereupon with a more coke forming feed in a higher part of the reactor. under such conditions that substantially on~y catalyst component A is selectively deactivated by coke deposition, in which process the suspension of the catalyst mixture containing catalyst component B and catalyst component A deactivated w;th coke i9 conducted in upward direction ;n the lower part of a fluldized catalyst bed, which catalyst bed consists of the catalyst mixture and is maintained at a temperature of from 475 to 600C, i.n which process a hydrocarbon product is sepa-rated from the fluidized catalyst bed which product is enriched with gasoline components by conversion of gaseous olefinic hydrocarbons under the influence of catalyst component B, and in w~ich process the catalyst mixture is stripped from the said fluidized bed and regenerated before it is recycl.ed in a hot state to the lower part of the reactor.
In this process the hydrocarbon mixture boiling above the gasoline range can be a gas oil and a more coke-forming feed can be a resi.dual oil. Additional C3 and C4 olefins may be added to the fluidized catalyst bed.
Variant IV
This variant relates to a process in wh;ch the cata-lyst mixture, in the form of a suspension, i.s first contacted at a temperature of at least 540 C, in the lower part of a vertically disposed reactor with a recycle o-l obta;ned in the catalytic cracking of a residual oil, and after a residence ti.me of the recycle oil in the reactor of from 0.5 to 4 seconds, with a residual oil in the h;gher part of the reactor. in a sufficient amount to termi.nate the cracking of the recycle oil. in which process the sus-pension containing the residual oil feed is conducted at a lower cracking temperature and at an additional residence time of from 0.5 to 6 seconds through the reactor. and in which process the suspension is separated into a cata-lyst phase and a hydrocarbon phase.

11~2118 In this process the conversion of the recycle oil and that of the res;dual oil are preferably restricted to 'ess than 50 and 45 ~v, respectively.
In this process the catalyst/oil rat;o of the SU9-pension in the area where the residusl oil is injected,may be set by adding a hot catalyst mixture to the 9US-pension.
In this process it is also possible to use a mixture of the separated catalyst mixture together with regenerated catalyst mixture for the conversion of a catalytic refor-mate into a product with a hi8her octane number.
To suppress metal and coke deposits on the catalyst mixture from the residual feed, gaseous materials, such as hydrogen, gaseous products obtained in the cracking of gas oil and Cl-C3 hydrocarbons, may be added to the resi-dual feed.
In this process i~ is also possible to use a separate second conversion zone in which a heavy straight-run naphtha or a light straight-run gas o-l is cracked at a temperature of at least 540 C with a suspension of the catalyst mixture into gasoline and in which subsequently this cracking is terminated by introducing a residual oil.
and in whic~ conversion of the residual o;l takes pl~ce by contact with the suspension of the cata]yst mixture.
Variant V
This variant relates to a process in which a gas oil is cracked in a first reactor at a temperature of from 540 to 650 C and a residence time of less than 5 seconds by contact with a suspension of the catalyst mixture, in which process a C3-containing hydrocarbon feed i9 converted 3 in a second reactor at a temperature of from 260 to 540 C
and a residence t;me of more than 5 seconds by contact with a suspension of the catalyst mixture of which part was ~1~2118 used in the first reactor, in which process the cataly~t mixtures used in the first and in the second reactor are colleceed in a fluidized bed, in which process the ~lu;dized bed is stripped, in which process the stripped catalyst mixture is regenerated, in wh;ch process the regenerated catalyst mixture is conducted at lea~t to the first reactor and in which process catalyst mixture separated from the first reactor is contacted in the se~ond reactor with a C3-conta;ning hydrocarbon material separated from the procuct of the first reactor.
In this process aro~atic components may be added to the C3~containing feed for the second reactor. The catalyst mixture used in the second reactor may consist completely of catalyst mixture originating from the first reactor or it may be a mixture of catalyst mixture originating from the first reactor and fresh, regenerated catalyse mixture.
In this process a third hydrocarbon feed containing C3 hydrocarbons may be added to the fluidi~ed catalyst bed.
The invent;on will now be further explained with reference to the following example.
Example A crystalline iron s;licate (silicate A? was prepared as follows. A mixture of FetN03~3, SiO2. NaN03 and /7C3H7)4N70H in water with the molar composition Na 0- 4-5/~C3H7)4 720- Fe203 29-1 S 2 2 heated for 48 hours in an autoclave at 150 C under auto-~enous pre~sure. After the reaction mixture had coo'ed down, the silicate formed was filtered off. washed with watPr until the pH of the wash water was about 8 and dried for two hours at ]20C. Silicate A thus prepared had the following chemical composit;on:
_ 3 7~4N720. 0.23 Na20. Fe203. 30 S;02. 9 H 0.

~Z1~8 l3 The silicate had an X-ray powder di.ffraction pattern substantially as given in Table B of Netherlands patent application No. 7613957. The silicate was thermally stab1e up to te~peratures higher than 1000C and after dehydration at 400 C! was capable of adsorbing 8.0 ~w water in vacuum at 25C and saturated water vapour pressure. With silicate A as the starting material. silicate B was prepared by successively calcining silicate A at 500 C, boiling with 1.0 molar NH4 NO3 solution, washi.ng with water, boiling lo again with 1.0 molar NH4NO3 solution and washing. drying at 120 C and calcining at 500C.
Two experiments were carri.ed out (experiments l and

2), in which a distillate obtained in the vacuum distillation of an atmospheric dist;llation residue of a crude mineral oil, was contacted with a cracking catalyst at a temperature of 485 C, atmospheric pressure, a space veloxity of ll kg.kg .h and a catalyst/o;l weight rat;o of 1.1:1. The results of the experiments are presented in the following table. The yields are based on the vacuum distillate feed.

Experiment No 1 2 raking catalyst Mixture of fauja- Mixture of fauja-site and silica- site, silica B
alumina matrix ;n and silica-alumina weight rat;o 1:~ matrix ;n weight ratio 1:1:9 Cracked gasoline Yield of fraction, ~w Octane number of this gasoline 82.4 88.6 (RON-O) Alkylation gasoline Yield of C3/C4 olefins, %w 6.9 13.2 Maximum gasoline yield which can be prepared from these C3/C4 olefins by alkylation with 10.0 22.3 isobutane, %w Octane number of this gasoline 93.1 93.4 (RON-O~

Claims

C L A I M S

1. A process for the preparation of gasoline from a hydrocarbon mixture boiling above the gasoline range, characterized in that a hydrocarbon mixture boiling above the gasoline range is cracked with use of a catalyst mixture containing components A and B, and in that a fraction boiling in the gasoline range is separated from the cracked product, and in that catalyst component A
is a crystalline aluminosilicate zeolite with a pore dia-meter of more than 9 .ANG.. and in that catalyst component B
is a crystalline silicate which (a) is thermally stable up to temperatures above 600°C, (b) after dehydration at 400°C in vacuum, is capable of adsorbing more than 3 %w water at 25°C and saturated water vapour pressure, and (c) in dehydrated form, has the following overall com-position. expressed in moles of the oxides (1.0 ? 0.3)(R)2/n0.[a Fe2O3.b Al2O3. c Ga2O3].
y(d siO2. e GeO2), where R = one or more monovalent or bivalent cations.
a ? 0.1, b ? 0, c ? 0, a + b + c = 1, y ? 10, d ? 0.1, e ? 0, d + e = 1, and n = the valency of R ,

2. A process according to claim 1, characterized in that use is made of a catalyst mixture of which 10-50 %w consist of catalyst components A and B and the rest of a porous matrix.

3. A process according to claim 1 or 2, characterized in that a catalyst mixture is used in which the components A and B are present in a weight ratio of from 10:1 to 1:3.

4. A process according to claim 1, characterized in that a catalyst mixture is used in which a component B is present of which, in the formula giving the overall composition, c and e are equal to 0.

5. A process according to claim 1, characterized in that a catalyst mixture is used in which a component B is present of which, in the formula giving the overall composition, a is greater than 0.5.

6. A process according to claim 5, characterized in that the catalyst mixture is used in which a component B is present of which, in the formula giving the overall composition, a is equal to 1.

7. A process according to claim 1, characterized in that a catalyst mixture is used in which a component B is present of which, in the formula giving the overall composition, y is less than 600.

8. A process according to claim 1, characterized in that a catalyst mixture is used whose alkali metal content is less than 1% w.

9. A process according to claim 1, characterized in that a catalyst mixture is used in which as component A a synthetic zeolite Y is present.

10. A process according to claim 1, characterized in that the catalytic cracking is carried out at a temperature of from 200 to 700°C, a pressure of from 1 to 10 bar and a space velocity of from 0.25 to 4 kg.kg-1.h-1.