JPS6250389A - Catalystic cracking method for enhancing octane value - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for catalytic cracking of hydrocarbon feedstocks. More specifically, the present invention relates to a method for improving the octane number of feedstocks treated by catalytic cracking.

BACKGROUND OF THE INVENTION In the catalytic cracking of hydrocarbon feedstocks, such feedstocks are cracked into low molecular weight products. One of the most important factors in determining catalytic cracking conditions is the octane number of the cracked products. Improving the octane number of decomposition products1
One method has been to use relatively expensive and specially formulated high octane cracking catalysts. However, the use of these catalysts is often not beneficial, especially when the feedstock contains significant amounts of metals such as nickel, vanadium, and/or iron. These metal contaminants become deposited on the cracking catalyst and promote the production of excess hydrogen and coke. The production of high octane cracking products often required frequent regeneration and/or replacement of cracking catalysts.

It has previously been noted that the presence of metal contaminants such as nickel, iron and vanadium on the cracking catalyst has the effect of increasing the octane number of the cracked products. US Patent No. 4
．． No. 200.520 sets the metal content of the catalyst to about 1500 to 4000 wppm equivalent nickel, preferably about 2.50 wppm.
A method is described for increasing the octane number of cracked products by maintaining it within the range of 0 to about 4.000 wppm. The desired metal levels are obtained by adding gas oil intermittently or continuously to the metal-containing heavy feedstock. This patent also suggests maintaining metal levels within a predetermined range by withdrawing high metal content catalyst from the system and adding low metal content catalyst to the cracking zone. However, the addition of metal-containing feedstocks can result in a large number of active metal sites contributing to excess hydrogen and coke production. Also, US Pat. No. 3,718.553 discloses that the octane number of a cracked feedstock can be improved by adjusting the metal content of the feedstock. This patent discloses reducing the amount of nickel, iron and/or vanadium in the catalyst to about 1% by pre-impregnating the catalyst with the desired amount and type of metal.
00 to about 1. It is disclosed that control is performed within the range of OOOwppm.

However, it has also been found that the presence of metal contaminants such as nickel, vanadium and iron in the cracking catalyst can result in excess hydrogen and coke production. Several patents have been issued disclosing methods for reducing the deleterious effects of metal contaminants on cracking catalysts. U.S. Patent No. 4.2
No. 80.8.95 and No. 4,28G, No. 896 discloses passing a decomposition catalyst through a reduction zone having a reducing atmosphere and maintained at an elevated temperature for a period of time ranging from about 30 seconds to 30 minutes. It is disclosed that the catalyst can be passivated by. These patents also disclose that selected metal contaminants can be added to the cracking system to improve the degree of passivation. U.S. Pat. No. 4.29a, 45
No. 9 describes a process for cracking metal-containing feedstocks which involves alternating exposures of up to 30 minutes to a cracking catalyst in an oxidation zone and a reduction zone maintained at elevated temperatures. U.S. Patent No. 4,268,416', U.S. Patent No. 4,361.496,
No. 4.364.848, No. 4.382.015, European Patent Publication No. 52.556 and PCT Patent Publication No. WO 104063 all discuss contacting metal pollution decomposition catalysts with reducing gases at elevated temperatures. A method for passivating a decomposition catalyst is described in which the catalyst is immobilized.

However, these publications do not disclose how to improve the octane number of the cracked products.

It would therefore be desirable to provide a process that allows for the production of cracked products having relatively high octane numbers without incurring the production of excess hydrogen and coke.

It would also be desirable to provide a method in which high octane cracking products are produced without the use of significant amounts of relatively expensive cracking catalysts.

It would also be desirable to provide a method in which the equilibrium catalyst removed from the cracker can be reused.

The present invention relates to a method for maintaining the metal content at a predetermined level and improving the octane number of cracked products by passing the regenerated catalyst from the regeneration zone to the passivation zone before returning it to the cracking zone.

SUMMARY OF THE INVENTION The present invention provides a method for cracking a hydrocarbon feedstock into low molecular weight products in a cracker system that includes a reaction zone, a regeneration zone, and a passivation zone by: (a) cracking a feedstock containing metal contaminants; (b) contamination with coke and metals; and (b) contamination with coke and metals. (c) passing the regenerated catalyst from the reaction zone to a passivation zone and then returning it to the reaction zone; , in a method for cracking a hydrocarbon feedstock consisting of (1
) monitoring the octane level of the cracked product; and (ii) adjusting the metal contaminant level of the catalyst to maintain the octane level within a predetermined range.

The present invention also provides for: (1) monitoring the amount of hydrogen and/or coke produced in the reaction zone; and (ii) adjusting catalyst metal contaminant levels to produce hydrogen and/or coke in the reaction zone. It also concerns keeping the amount within the planned range.

The present invention also includes: (1) monitoring the metal contaminant level of the cracking catalyst; and (ii) adjusting the metal contaminant level of the cracking catalyst to maintain the metal contaminant level of the catalyst within a predetermined range. It can also be implemented by

The metal contaminants may be nickel, vanadium or mixtures thereof. The metal contaminant level of the cracking catalyst is preferably greater than about 400 wppm equivalent nickel, more preferably from about 600 to about 2,300 wppm.
within the range of nickel equivalents and most preferably about 700
to about 2,3000 wppm equivalent nickel.

The octane level of the cracked products is a function of many variables, including the feedstock used, the catalyst used, and the process conditions in the reaction zone. Typically, the decomposition products are
Research Octane Number (R) in the range of about 85 to about 95
ONC).

The amount of hydrogen and coke produced in the reaction zone is a function of the feedstock used, the catalyst used, and the process conditions in the reaction zone. The amount of hydrogen and/or coke produced that can be tolerated depends on the design of each cracking system.

When using vacuum gas oil as feed to the cracking system, hydrogen production is typically below 20 OSCF/metered feedstock barrel (fresh feed + recycle), preferably below about 15O8CF/barrel. below and more preferably within the range of about 25-75 SCF/barrel.

In one method of practicing the invention, a metal contaminant decomposition catalyst is added to the cracking system to maintain metal contaminant levels on the cracking catalyst within a predetermined range. The metal-contaminated catalyst preferably accounts for about 5 to about 100 1 of the total exchange catalyst added to the cracking system.
i: Corresponds to XK. This process is particularly useful for producing relatively high octane products from feedstocks having relatively low metal contaminant content, such as vacuum gas oil.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, a schematic diagram of a cracker system is shown. In this drawing, all pumps, valves, gauges and related equipment not necessary for an understanding of the invention have been removed for clarity. The illustrated reaction or cracking zone 1G is a fluidized catalyst bed 12 having a level indicated by the reference numeral 14.
and into this fluidized bed a hydrocarbon feedstock is introduced via line 16 for catalytic cracking. Hydrocarbon feedstocks may be derived from naphtha, light gas oil, heavy gas oil, resid fractions, vacuum distilled crude oil, circulating oils derived from any of these, as well as Shae A oil, kerogen, tar sands. It may be any suitable fraction obtained from the treatment of bitumen, a synthetic oil, an oil obtained from the hydrogenation of coal, etc.

Heavy feedstocks such as deasphalted oils, high endpoint gas oils, atmospheric and/or vacuum distillation residues typically contain relatively high concentrations of vanadium and/or nickel i.e. 650% to the reaction zone. 'F+ based on feedstock from about 2 to about 1.
600 wppm of the metal, whereas light feedstocks such as heavy naphtha, light recycle oil, paraffinic gas oil, hydrotreated naphtha, and light recycle oil typically contain reduced amounts of vanadium. and/or nickel, or about 0.001 to about tOwppm metal.

Hydrocarbon gas and/or steam passing through the fluidized bed 12 maintains the bed in a dense, turbulent fluid state. The decomposed vaporized products exit zone 10 via line 52. In reaction zone 10, the cracking catalyst typically becomes exhausted due to the deposition of coke thereon during contact with the hydrocarbon feedstock. As used herein, a "spent" or "coke-contaminated" catalyst is defined as having sufficient coke on it to pass through the reaction zone and cause deactivation, thereby requiring regeneration. means a catalyst that

Generally, the coke content of the spent catalyst is from about 0.5 to
Vary between about 5% by weight or more.

Prior to substantive regeneration, the spent catalyst enters stripping zone 18 from reaction zone 10 where it is transferred to line 2.
0 into zone 18. A stripping gas such as steam serves to remove most of the volatile hydrocarbons remaining on the catalyst. The stripping zone is typically maintained at essentially the same temperature as the reaction zone, ie, about 450 to about 6 oo<0>C. The spent catalyst, which has been stripped to remove most of the volatile hydrocarbons, enters the connecting vertical riser 24 from the bottom of the stripping zone 18 via a droplet bend 22 . Vertical riser 24 extends into the lower portion of playback zone 26 . The air introduced into the riser 2'4 via line 28 reduces the density of the catalyst flowing therein, so that the catalyst flows upstream into the regeneration zone 26 with a simple pressure balance.

The illustrated playback band 26 is designated by the reference numeral 32 .

It contains a dense phase catalyst bed 30 having a level. This catalyst bed 60 undergoes regeneration to burn off coke deposits formed in the reaction zone during the cracking process.

Above the dense phase bed 30 is a dilute phase 34 . The oxygen-containing regeneration gas enters the lower portion of the regeneration zone 26 via line 36 and passes upstream through the grid and dense bed 30, thus maintaining the bed in a turbulent flow condition similar to that present in the reaction zone 10. do. Flue gas from regeneration zone 26 exits regeneration zone 26 via line 60 . The design and operating conditions of reaction zone 10 and regeneration zone 26 are not critical;
Well known to those skilled in the art. Regenerated catalyst from regeneration zone M, 26 flows through standpipe 42, U-bend 44 and line 80 to passivation or reduction zone 70. This passivation zone 70 is maintained at a temperature greater than 500°C, preferably greater than 600°C, and conduit 72 is maintained to maintain a reducing environment in the passivation zone and thereby passivate metal contaminants. - a reducing agent such as hydrogen, carbon oxide, light hydrocarbons such as C1-C3 hydrocarbons or mixtures thereof. As explained in detail below and as described in U.S. Pat. No. 4,280,895, the reduction or passivation zone 70 provides adequate contact between the catalyst and the reducing environment at elevated temperatures. It can be any container in which it is provided.

The shape of passivation zone 70 is not critical. In the illustrated embodiment, passivation zone 70 has a similar shape to regeneration zone 26, and a reducing environment is maintained and the catalyst is fluidized by the reducing agent entering via line 72 and exiting via line 78. be done. The residence time of the catalyst in passivation zone 70 is not critical, provided that the catalyst is sufficiently passivated. Passivated catalyst from passivation zone 70 enters reaction zone 10 through return pipe 82 and U-bend 84. The residence time in the passivation zone 70 is:
It may range from about 5 seconds to about 30 minutes. The pressure in the passivation zone 70 is not critical and is generally a function of the position of the passivation zone in the system and the pressures of the adjacent regeneration and reaction zones. The temperature of passivation zone 70 is greater than about 500°C, preferably about 600°C.
but below the temperature at which the catalyst sinters or degrades. A preferred temperature range is from about 600 to about 800°C, and a more preferred temperature range is from about 650 to about 750°C. Passivation zone 70
is preferably located after the regeneration zone so that the heat imparted to the catalyst by regeneration reduces or minimizes the need for additional catalyst heating in the passivation zone. Passivation zone 70 may be constructed of any chemically resistant material that can withstand the relatively high temperature and wear conditions inherent in fluidized catalyst systems. The particular reducing agent used in passivation zone 7o is not critical. Typically,
The reducing agent used is one that is readily available. Examples of suitable reducing agents are catalytic cracker tail gas, catalytic reformer off-gas, spent hydrogen stream from catalytic hydrotreating, synthesis gas and flue gas. Passivation zone 7o
The rate of consumption of the reducing agent in the passivation zone depends on the amount of reducing material entering the passivation zone. In a typical fluidized cracking system, about 1 to about 1 ton of catalyst is passed through passivation zone 70.
It is expected that 0.00 scf of hydrogen will be required.

As shown in the examples below, the metal content of the cracking catalyst is approximately 4
00 Wppm preferably from about 600 to about 2
Maintaining within the range of 500 wppm equivalent nickel provides cracked products with improved octane numbers without producing excessive amounts of hydrogen and coke and without significantly reducing conversion. The term "nickel equivalent" as used herein is defined as "N1-)-".

A series of tests were conducted to compare naphtha yield, octane hydrogen production, and coke production using low and high metal content equilibrium cracking catalysts. The term “
"Equilibrium catalyst" is defined as a cracking catalyst removed from a cracking system operated under steady state conditions.

The equilibrium decomposition catalyst used was "5upper DX", a silica-alumina zeolite decomposition catalyst manufactured and sold by Davison Chemical Company, a division of W.R. Brace & Company.
It was a catalyst.

The low metal balance catalyst consisted of 185 wppm nickel and 220 wppm vanadium resulting in a catalyst with an equivalent nickel of approximately 240 wppm. High metal content equilibrium catalysts are additive to low metal content equilibrium catalysts.
1.000 wppm nickel and 4.000 wp
Impregnated with vanadium of pm to about 2.240 wpp
was prepared by producing a catalyst with an equilibrium nickel of m. Both catalysts were used without passivation treatment and were used at 4 lb/lb feedstock introduced.
of the eluent was circulated to the reaction zone. The composition of the product is A
Measured by adsorption with a fluorescent indicator as described in STM D1319. From Table 1, when comparing the octane number when using a high metal content equilibrium catalyst with the low metal content equilibrium catalyst, the single research octane number (RONC) improved by about 4.3, and the single motor octane number increased by 2. .8
It can be seen that there has been some improvement. However, it should be noted that for the high metal content catalyst, the presence of metals more than doubled coke production and increased hydrogen production by a factor of X10.

EXAMPLE 1 This example shows that passing a high metal contaminant catalyst through the passivation zone with a residence time of 20 minutes or 7 hours prior to use improved research and motor performance without producing excess lid coke and hydrogen. This indicates that a decomposition product having an octane number was produced. This data is also shown in Table 1.

Table 1 Characteristics of decomposition products High metal content Equilibrium 5uper DX Low metal content H2 treatment Metal content Equilibrium 5uperDX oxidation 20 minutes 7 hours Equilibrium Ni, wppm 240 2,2
40 2240 2.240 conversion rate, LVX
68.2 64.6 64.7 69.
4 Naphtha yield 58.5 49.6 4
9.7 55.1 Selectivity 85J3
7&5 76B 79.4RONC88,5
92-893,592,7M0NC7EL7
8t5 [08t5 naphtha composition saturated product 3t2 52.2 56
．． 2 40.9 Olefin 442
37.6 28,6 28.7 Aromatic
24.6 5α2 35,2311.4 Coke, wt, % &O&9 4.0
Easy hydrogen, wt, XQ, 08 cL77 (L
28 Q, 24 From Table 1, exposing the high metal contaminant content catalyst to passivation zone 701C reduced coke production and hydrogen production to virtually the same levels as produced with the low metal contaminant catalyst. I understand that. Surprisingly, however, research and motor octane numbers were similar to those obtained with high metal contaminant catalysts that were not exposed to passivation zone 70, despite the differences in naphtha composition caused by the reduction process. It should be noted that they were virtually the same.

Thus, it can be seen that zone 70 passivates the catalyst without significantly reducing the ability of the metal contaminant levels to produce cracked products with improved research and motor octane numbers.

To investigate the preferred metal level range of the cracking catalyst, 4
00.600.700.800.1100 and 1450
5upper with an equilibrium nickel of Wppm
Additional tests were conducted using a DX cracking catalyst. Equivalent nickel levels in the cracking catalyst were increased to 1.
OOO wppm of nickel and 4,000 wppm
400 wppm Kara'L 450 by adding in portions an equilibrium catalyst pre-impregnated with vanadium.
increased to wppm. At each metal level, 95
Research and motor octane levels, hydrogen and coke production were measured on the unimmobilized catalyst used in the reaction zone maintained at 0°F and 15 psig. In this case, 4 lb of catalyst was circulated per lb of feed introduced. The results are plotted in Figures 2.3 and 4.

Example 2 In this example, various catalyst samples impregnated with equivalent amounts of 400 to 450 wppm of nickel were exposed to hydrogen atmosphere for 1 to 3 hours.
00111'' for 2 hours. The catalyst was then used in a reaction zone maintained at 950'F and 15 psig. In this case, 4 lb of catalyst was circulated per lb of feed introduced. Ta.

Research and motor octane numbers are plotted in Figure 2, and hydrogen and coke production are plotted as a function of catalyst metal contaminant levels in Figures 3 and 4, respectively.

Figure 2 shows that the level of metal contaminants in the catalyst is particularly low at 700 wpp.
Both research and motor octane numbers show an improvement as m is increased above equivalent nickel. The figure also shows that the passivated catalyst samples generally yielded higher octane numbers at comparable metal content to the unpassivated catalyst samples. 3rd and 4th
The figure shows that as the metal level of the catalyst increases, hydrogen and coke production improves for both the passivated and unpassivated catalyst samples. However, the passivated catalyst sample shows a much smaller improvement in hydrogen and coke production than the unpassivated sample. In particular, it is noteworthy that for the passivated catalyst samples, hydrogen production did not show substantial improvement until reaching metal contaminant levels higher than 700 wppm equivalent nickel. Similar K
, coke production did not show a significant increase until after 800 wppm equivalent nickel was added to the catalyst.

Thus, the process of the present invention can be utilized to produce cracked products with improved octane numbers without incurring excess hydrogen and coke production. This is illustrated by the data summarized in Table 2. Table 2 summarizes the octane numbers, hydrogen and coke production for catalysts with varying metal levels.

Table 2 Metal content at 1300°F in H2; Equilibrium Ni, wppm 400 80
0 1450RONCB7.9 88,7
89.6M0NC77,979,279,5 H2Wt,X α065 0.0
99 (L125: I-ri, t, wt, X
2.7 S u &2
From the data in Table 2, it can be seen that the 800 wppm equivalent Ni catalyst has no increase in coke production and only a negligible increase in hydrogen production by 0.8% compared to the unpassivated catalyst, respectively.
It can be seen that this resulted in a decomposition product with improved RONC and MONC values of t3 and t3. 1 a so
For wppm equivalent nickel, t7 and t in RONC and MONC values, respectively, compared to unpassivated catalyst.
An improvement of 6 was obtained. 0.06Njk% and α, respectively
An increase in hydrogen and coke production of 4% by weight is not considered detrimental in view of the significant octane improvement obtained.

When the feedstock has a relatively low metal content, such as a vacuum gas oil fraction, one method to maintain elevated catalytic metal levels is to use metal-contaminated equilibrium catalysts from other cracking zones. That's true. The addition of such an equilibrium catalyst thus serves a dual purpose. Increasing catalytic metal levels improves the research motor octane number of the cracked product, whereas reusing the equilibrium catalyst reduces the cost of replacement catalyst added to the system. In such systems, the extent to which equilibrium catalyst is added depends on the desired metal content of the catalyst in the cracking system, the metal content of the equilibrium catalyst to be added, the desired degree of conversion of the catalyst due to attrition and other losses, and the inflow. Included the metal content of the feedstock. Depends on several factors. When using feedstocks with relatively high metal content, such as high end point gas oils, deasphalted oils, and atmospheric and/or vacuum distillation residues, the metal content of the catalyst is
By reducing the degree of catalyst exchange for the cracking system and (
or) metal contamination can be maintained at a relatively high level by adding an amount of equilibrium catalyst to the system. The metal-contaminated catalyst accounts for about 5 to about 100 of the total exchange catalyst added to the system.
Preferably it corresponds to % by weight.

Although the present method has been described with respect to particular embodiments, it will be understood that the method is susceptible to further modifications. Therefore, it should be understood that the present invention is not limited to the specific examples described above.

FIG. 1 is a schematic flow diagram illustrating one method for carrying out the invention, with reference numeral 10 being a reaction zone, 26 being a regeneration zone and 70 being a passivation zone.

FIG. 2 is a graph plotting the single research and motor octane numbers as a function of the equivalent nickel contaminant level of the catalyst for both passivated and unpassivated cracking catalysts.

FIG. 3 is a graph of hydrogen production as a function of equivalent nickel contaminant level of the catalyst for both passivated and unpassivated cracking catalysts.

FIG. 4 is a graph plotting coke production as a function of catalyst equivalent nickel contaminant level for both passivated and unpassivated cracking catalysts.

Hiroshi Fuma and 1-゜(,
−) Of the drawing? ? W (No change in content) F/θ, / EONi, IIIPPM F no G, 3 EO,! II, IPPM ・- 了击烹きO-ξ 4hi FIG, 4 EO, Ni, WPPII Procedural amendment (method) % formula % Display of the case 1985 Patent application No. 185956 Title of the invention Octane number-enhancing catalytic cracking person who makes legal amendments

Claims (9)

[Claims] (1) In cracking a hydrocarbon feedstock into low molecular weight products in a cracker system comprising a reaction zone (10), a regeneration zone (26), and a passivation zone (70), the hydrocarbon feedstock contains (a) metal contaminants; (b) passing the feedstock to a reaction zone having a cracking catalyst, which cracks the feedstock into low molecular weight products and coke, such that the coke and metal contaminants become deposited on the catalyst; (c) passing the catalyst contaminated with coke and metals from the reaction zone to a regeneration zone (26) where coke is removed from the catalyst to regenerate the catalyst;
passing the regenerated catalyst from (i) to a passivation zone (70) before returning to the reaction zone (10).
1. A process for cracking a hydrocarbon feedstock, comprising: (i) monitoring the octane level of the cracked product; and (ii) adjusting the catalyst contaminant level to maintain the octane level within a predetermined range. 2. The method of claim 1 further characterized in that the metal contaminants are selected from the group consisting of nickel, vanadium, and mixtures thereof. 3. The method of claim 1 or claim 2 further characterized in that metal contaminant levels are maintained within predetermined limits by the addition of a metal contaminant catalyst to the cracking system. (4) The metal contaminant level of the decomposition catalyst is about 400 to about 2
. , 300 wppm. (5) The metal contaminant level of the decomposition catalyst is about 600 to about 2
5. A method according to any one of claims 1 to 4, further characterized in that the equivalent nickel content is maintained within the range of , 3000 wppm. (6) Claims 1 to 3 further characterized in that the metal-contaminated catalyst is added to a decomposition system consisting of an equilibrium decomposition catalyst.
The method described in any one of Item 5. (7) Any of claims 1 to 6 further characterized in that the equilibrium cracking catalyst is added to the cracking system in an amount representing from about 5 to about 100% by weight of the total exchange catalyst added to the cracking system. or the method described in paragraph 1. (8) A method according to any one of claims 1 to 7, further characterized in that the equilibrium cracking catalyst added to the cracking system has a higher equivalent nickel content than the cracking catalyst in the reaction zone. . (9) (i) monitor hydrogen and/or coke production in the reaction zone; and (ii) adjust catalyst metal contaminant levels to
9. The method according to claim 1, further comprising: or) maintaining the coke production within a predetermined range.