CA1281677C - Process for catalytic dewaxing to improve pour point using zsm-11 catalyst containing hydrogenation/dehydrogenation component - Google Patents

Abstract

PROCESS FOR CATALYTIC DEWAXING TO IMPROVE POUR POINT

HYDROGENATION/DEHYDROGENATION COMPONENT

ABSTRACT OF THE DISCLOSURE
Waxy distillate is catalytically dewaxed using a catalyst comprising ZSM-11 and a hydrogenation/dehydrogenation component to lower the pour point of the distillate.

Description

1~.8~677 PROCESS FOR CATALYTIC DEWAXING TO IMPROVE POUR POINT
USING ZSM-ll CATALYST CONTAINING
HYDROGENATION/DEHYDROGENATION COMPONENT

BACKGROUND OF THE INVENTION

1. Field of the Invention This invention is a process for catalytic dewaxing of oil stocks using ZSM-ll, to improve pour point of the oil.

2. Prior Art Modern petroleum refining is heavily dependent on catalytic processes which chemically change the naturally occurring constituents of petroleum. Such processes include hydrocracking, catalytic cracking, reforming and hydrotreating. Historically, the processes all depended on the discovery that chemical change could be induced by contacting a suitable petroleum fraction with a suitable porous inorganic solid at elevated temperature. If hydrogen under pressure is essential to the desired conversion, such ~ as in hydrocracking, a hydrogenation metal is included with ;~ 20 the porous catalyst to make the hydrogen effective.

The porous inorganic solids that were originally found~useful for catalytic processes included certain clays, aluminas, silica-aluminas and other silicas coprecipitated :: :

~ 7 7 with magnesia, for example, and such solids are still extensively used in the industry. In general, all of these solids had pores that were not of uniform size, and most of the pore volume was in pores having diameters larger than about 30 Angstroms, with some of the pores as large or larger that lO0 Angstroms. As will become evident from the paragraphs which follow, a large fraction of the molecules present in a hydrocarbon feed, such as a gas oil, is capable of entering the pores of the typical porous solids described above.
In recent years much attention has been given to the synthesis and properties of a class of porous solids known as ~molecular sievesn. These are porous crystalline solids usually composed of silica and alumina, and, because the pore structure is defined by the crystal lattice, the pores of any particular molecular sieve have a uniquely determined, uniform pore diameter. The pores of these crystals are further distinguished from those in the earlier used solids by being smaller, i.e., by having effective pore diameters not greater than about 13 Angstroms. These solids, when dehydrated, act as sorbents that discriminate among molecules of different shape, and for that reason were first called "molecular sieves" by J. W. McBain. The term "effective pore diameter~ as used herein means the diameter of the most constricted part of the channels of the dehydrated crystal as estimated from the diameter of the largest molecule that the ~; ~ crystal is capable of sorbing. Zeolite molecular sieves are available that have effective pore diameters ranging from about 3 Angstroms, which is too small to allow occlusion of any hydrocarbon in the pores, to about 13 ~ ~ .
~ -2-X

~816~

Angstroms, which 3110ws occlusion of molecules as large as 1,3,5-triethylbenzene. The structures and uses of these solids are dlescci~ed in "Zeolite Molecular Sieves," by Donald w.
8ceCK~ Jonn Wiley and Sons, New York (1974)-As indicatea by Breck, the zeolite molecular sieves ace use~ul as adsorbents (ibid, ~age 3), and in catalvsts (ibia, page 2).
In s?ite of the small pores which are cnaracteristic of zeolite molecular sieves, certain of these materi~ls have been found to be highly effective as hydrocarbon conversion catalysts. The conversion of gas oil to gasoline and distillate by catalytic cracking, the alkylation of benzene to ethylbenzene, the isomerization of xylenes and the disproportionation of toluene all involve molecules which are smaller in critical diameter than 1,3,5-triethylbenzene, and such molecules are occluded and acted upon by zeolite molecular sieves havinq an effective pore diameter of about 10 Angstroms. A particularly interesting catalytic transformation whic'n requires a molecular sieve catalyst is the reduction o~
the pour point of waxy distillates and residual hydrocarbon fractions. Effective pour point reduction depends on the selective conversion of normal, high melting point paraffin molecules that have an effective critical diameter of about 5 Angstroms to substances of lower molecular weight that are easily separated fcom the low-pour product. ~ffective ; catalytic dewaxing depends at least in part on the regularity of the pore size of the crystalllne zeolites, which allows selective convecsion of unwanted constituents.

The developments briefly described above are only indicative of the commercial importance of the molecular sieve zeolites and of the academic interest in these materials, which is more accurately reflected by the thousands of patents and publications on the subject. By far the major part of this importance stems from the catalytic properties that may be found in appropriate circumstances within the relatively small pores, together with the regularity in the shape of the pores which permits the molecular sieve catalyst to act selectively on molecules having a particular shape. This latter phenomenon has come to be known as ~shape-selective catalysis~. A review of the state of the catalytic art is found in "Zeolite Chemistry and Catalysis" by Jule A. Rabo, ACS Monograph 171, American Chemical Society, Washington, D.C. (1976).
The dewaxing of oils by shape selective cracking and hydrocracking over ZSM-5 zeolites is discussed and claimed in Re 28,398 to Chen et al. U.S. Patent 3,956,102 discloses a particular method for dewaxing a petroleum distillate with a ZSM-5 catalyst. Typical aging curves as shown in sheet 2 of the drawing of the 3,956,102 patent. U.S. 3,894,938 to Gorring et al discloses that the cycle life of a ZSM-5 dewaxing catalyst is longer with a virgin feed strea~ than it :
is with the same feedstream after it has been hydrotreated.

25~ Catalytic dewaxing of petroleum stocks in which a mordenite type of molecular sieve catalyst is used is described in the Oil and Gas Journal, January 6, 1975 issue at pages 69-73.

~See also U.S. Patent 3,668,113.

: :~

:
~ -4-~ .

~ 7'7 Crystalline zeolite ZSM-ll is disclosed and claimed in U.S. Patent 3,709,979.
In U.S Patent 3,709,979, the preparation of ZSM-ll is disclosed. Example 9 of this patent taught fluid S catalytic cracking at 8750F of a gas oil having a pour point of 100F. High yields of olefins were obtained. The pour point of the product was reduced.
Later patents relating to improvements in the catalytic dewaxing process taught that the use of shape selective zeolites for catalytic dewaxing was preferred.
These references taught that any shape selective zeolite with a constraint index of l to 12, as hereafter defined, could be used but that ZSM-5 and ZSM-ll were especially preferred.
The only work reported was done on ZSM-5 catalyst.
Typical of these patents is U.S. 4,181,598. This patent taught making lube base stock oii of lower pour point from a waxy crude oil fraction by solvent refining, catalytic dewaxing over an intermediate pore size zeolite, e.g., ZSM-5, followed by hydrotreating.
U.S. 4,332,670 taught catalytic dewaxing of middle distillates to produce a low pour fuel oil by using an intermediate pore size zeolite. There are no examples showing use of ZSM-ll.
U.S. Patent 4,357,232, taught catalytic dewaxing of ~25 lubricating base stock oils using an intermediate pore size zeolite, e.g., ZSM-5, along with other treatment steps. Use of ZSM-5 and ZSM-ll as preferred is mentioned, although no examples are reported showing use of ZSM-ll.

:~ ' .

8~.~7'7 U.S. Patent 4,348,363 taught a method of reducing the pour point of a waxy hydrocarbon fuel oil by contact with a zeolite sorbent, followed by catalytic dewaxing over an intermediate pore size zeolite. Use of ZSM-5 and ZSM-ll as preferred is mentioned, although no examples are reported showing use of ZSM-ll.
U.S Patent 4,361,477 teaches catalytic dewaxing using intermediate pore size zeolites having high silica to alumina mole ratios, along with other treating steps. ZSM-5, ZSM-ll and silicalite are taught, and claimed as being suitable for use in this process. No examples using ZSM-ll were presented.
Another method of producing low pour point lubricating oil stock using catalytic dewaxing is disclosed in U.S. 4,372,839. This patent taught use of intermediate pore size zeolites such as ZSM-5 or ZSM-ll for catalytic dewaxing, along with other processing steps. No examples of use of ZSM-ll were given.
U.S. Patent 4,325,805 teaches lubricating oil stabilization, involving catalytic dewaxing with an intermediate pore size zeolite and other processing steps.
Taught as suitable intermediate pore size zeolites were CZH-5, ZSM-5, ZSM-ll, ZSM-12, etc. The preferred zeolites were ZSM-5 and CZH-5: No examples were provided of use of ZSM-ll for catalytic dewaxing.
U.S. Patent 4,361,477 teaches stabilizing and ; ~ dewaxing lube oils using catalytic dewaxing with an intermediate pore size zeolite and other processing steps.

.

~ 7 8 Taught as suitable intermediate pore size zeolites are ZSM-5, ZSM-ll, ZSM-12, ZSM-21, etc. No examples are given using ZSM-l].
In U.S. Patent 4,394,251, essentially aluminum-free intermediate pore size zeolites analogous to ZSM-5 and ZSM-ll are taught as suitable for cracking and hydrocracking. No examples are given showing use of ZSM-ll for catalytic dewaxing.
Although catalytic dewaxing is an important commercial process, and although there has been extensive work reported in the patent literature, apparently no one has used ZSM-ll for catalytic dewaxing of fuel oil. Some researchers imply an equivalence between the two, saying that ZSM-5 and ZSM-ll are especially preferred, but invariably the only zeolite actually tested for catalytic dewaxing are ZSM-5 zeolites.
Hydrocracking of n-decane with Pt-containing ZSM-11 has been reported in an article entitled ~Shape-Selectivity Changes in High-Silica Zeolites", Jacobs et al, Faraday Disc.
Chem. Soc. (1982), 72,353.
We studied the work that others had done in this :
area with a view to improving the process for catalytic dewaxing of fuel to see if a way could be found to make this good process even better by obtaining a catalyst of higher ~2~5 activity. We discovered that Pt-ZSM-ll, which has been ignored experimentally by all prior workers in distillate dewaxing, is better for catalytic dewaxing than Pt or ~ Ni-ZSM-5.

:~:

~:
__ ~ ~8~677 BRIEF SUMMARY OF THE INVENTION
Accordingly~ the present invention provides a process for reducing the pour point of a waxy hydrocarbon fuel oil which comprises contacting said oil at catalytic dewaxing conditions including a temperature about 450 to 850F in a reaction zone in the presence of hydrogen with a catalyst comprising ZSM-ll and a hydrogenation/dehydrogenation component to produce a dewaxed fuel oil with reduced pour point.
In another embodiment, the present invention provides a process for reducing the pour point of a waxy hydrocarbon fuel oil which comprises contacting said oil at catalytic hydrodewaxinq conditions including a temperature of about 450 to 850F in a reaction zone containing a fixed bed of catalyst comprising ZSM-ll and a platinum group component and wherein catalytic hydrodewaxing conditions include a hydrogen partial pressure of 25 to 1000 psia and a ratio of hydrogen to hydrocarbon of 500 to 5000 SCFB and a liquid hourly space velocity of 0.5 to 5 hours l to produce a dewaxed fuel oil product with a reduced pour point.

DETAILED DESCRIPTION
2SM-ll Details of preparation of ZSM-ll are given in U.S.
: ~ Patent 3,709,979.
~ :~ An important characteristic of the crystal structure ; ~;
of this novel class of zeolites is that it provides a selective constrained access to and egress from the ~: :
~ : intracrystalline free space by virtue of having an effective ;
:~
~ 8-::
~ :

~ L~77 pore size intermediate between the small pore Linde A and the large pore Linde X, i.e. the pore windows of the structure are of about a size such as would be provided by 10-membered rings of silicon atoms interconnected by oxygen atoms. It is to be understood, of course, that these rings are those formed by the regular disposition of the tetrahedra making up the anionic framework of the crystalline zeolite, the oxygen atoms themselves being bonded to the silicon (or aluminum, etc.) atoms at the centers of the tetrahedra.
The silica to alumina mole ration referred to may be determined by conventional analysis. This ratio is meant to represent, as closely as possible, the ratio in the rigid anionic framework of the zeolite crystal and to exclude aluminum in the binder or in cationic or other form within the channels. Although zeolites with silica to alumina mole ratios of at least 12 are useful, it is preferred to use zeolites having higher ratios than about 15, preferably about 15 to 200. In addition, zeolites as otherwise characterized herein but which are substantially free of aluminum, that is zeolites having silica to alumina mole ratios of up to infinity, are found to be useful and even preferable in some instances. Such "high silica~ or ~highly siliceous~ zeolites are intended to be included within this description. Also included within this definition are substantially pure silica ~25 analogues of the useful zeolites described herein, that is to say those zeolites having no measurable amount of aluminum (siliea to alumina mole ratio of infinity) but which otherwise embody the characteristics disclosed.
In general, higher aluminum contents in the zeolite ~ ' _g_ lZ~ '7 framework give more acid activity to the catalyst. The acid activity may be adjusted by crystallizing the ZSM-ll with only a little, or a lot, of aluminum, steaming the ZSM-ll, acid extracting, or any other means conventionally used to adjust acid activity.
The novel class of zeolites, after activation, acquire an intracrystalline sorption capacity for normal hexane which is greater than that for water, i.e. they exhibit "hydrophobic~ properties. This hydrophobic character can be used to advantage in some applications.
The novel class of zeolites useful herein have an effective pore size such as to freely sorb normal hexane. In addition, the structure provides constrained access to larger molecules.
The ~Con~traint Index~ as herein defined may be detemined by passing continuously a mixture of an equal weight of normal hexane and 3-methylpentane over a sample of zeolite at atmospheric pressure according to the following procedure. A sample of the zeolite, in the form of pellets or extrudate, is crushed to a particle size about that of coarse sand and mounted in a glass tube. Prior to testing, the zeolite is treated with a stream of air at 1000F for at least 15 minutes. The zeolite is then flushed with helium and the temperature is adjusted between about 550F and ~25 ; 950F to give an overall conversion of between 10~ and 603. The mixture of hydrocarbons is passed at 1 liquid hourly space velocity (i.e., 1 volume of liquid hydrocarbon per volume of zeolite per hour) over the zeolite with a helium dilution to give a helium to : _ _ (total) hydrocarbon mole ratio of 4:1. After 20 minutes on stream, ~ sample of the effluent is taken and analyzed, most conveniently by gas chromatography, to determine the fraction remaining ~nchanged for each of the two hydrocarbons.
While the above experimental procedure will enable one to achieve the desired overall conversion of 10 to 60% for most ~eolite samples and represents preferred conditions, it may occasionally be necessary to use somewhat more severe con~itions tor samples of very low activity, such as those having an exceptionally high silica to alumina mole ratio. In those instances, a temperature of up to about 1000F and a liquid hourly space velocity of less than one, such as 0.1 or ; less, can be employed in order to achieve a minimum total l conversion of about 10~.
15 l The "Constraint Index" is calculated as follows:
Constraint Index =

(~-ct~n ~ ~e~ aining) ~lo (~rac ~
The Constraint Index approximates the ratio of the cracking rate constants for the two hydrocarbons. Constraint 20 '1¦ Index (CI) values for some typical materials are: ¦

~ ! C.I.
ZSM-4 0.5 ! ZSM-5 8.3 ZSM-ll 8.7 2SM-23 9.1 2SM-3, 4.5 TMA Offretite 3.7 Clinoptilolite 3.4 H-Zeolon (mordenite) 0.4 REY
Amorphous Silica-Alumina 0.6 Erionite 38 :::

~8~77 CATALYTIC DEWAXING TO IMPROVE PO~R POINT
Catalytic dewaxing of high-pour gas oils to low-pour fuel oils over a shape selective zeolite catalyst such as ZSM-5 is described in U.S. Patent No. 3,700,585 and its reissue, RE. 28,398.
A good general discussion of catalytic dewaxing to improve pour point is shown in Chen, N. Y. et al "New Process Cuts Pour Point of Distillatesn, Oil and Gas Journal, Vol.
75, No. 23, June 6, 1977, page 165 and Ireland et al I0 ~Distallate Dewaxing in Operation~, Hydrocarbon Processing, May, 1979.
In very general terms, catalytic hydrodewaxing operates with a fixed or moving bed of catalyst, although other types of catalyst beds such as ebulating bed, moving bed, fluidized bed, may also be used.
Catalytic dewaxing for pour point improvement usually requires somewhat higher temperatures than catalytic dewaxing to prepare a lubricating oil base stock, i.e., temperatures of 450 to 850F, and preferably 500 to 800F
are commonly used for catalytic dewaxing to improve pour point.
A certain amount of hydrogen partial pressure is essential, both to minimize coke formation and laydown on the catalyst, and also because hydrogen is consumed in cracking ~25~ ~ of normal paraffins to lighter molecules. Hydrogen is also ~ ~ helpful in promoting hydroisomerization of long chain ; ~ ~ paraffins or slightly branched paraffins to more highly branched paraffins.

~ 7 7 Hydrogen partial pressures of 15 to 2000 psia give good results, while hydrogen partial pressures of 100 to 1000 psia give very qood results.
The ratio of catalyst to oil, expressed as liquid hourly space velocity or volume per hour of normally liquid feed measured at 0~ per volume of catalyst may range from about 0.1 to 10 hours 1, preferably about 0.5 to 5 hours l The alnount of hydrogen present may vary greatly, ranging from 5dO to 5000 standard cubic feet per barrel of oil. It is possible to operate with even less hydrogen, although the catalyst will deactivate somewhat more ~uickly than if the preferred minimum amount of hydrogen, 500 SCFB, is added to the feed to the catalytic dewaxing zone. It is also !
I¦ possible to operate with even more hydrogen being pre-~ent, however, it is expensive to circulate such large volumes of hydrogen through the reactor, and the small increase in catalyst life does not justify the expense of such high hydrogen circulation rates.

, I . ~.. .
It ls frequently advantageous to conduct hydrotreating either immediately before or after catalytic dewaxing.
~Hydrotreating will usually be practiced when necessary to remove sulphur or nitrogen or to meet some other product specification.
The advantage of hydrotreating the feed before sub~ecting it to catalytic dewaxing, is that many catalyst poisons will be either converted catalytically in the ~ . .
.

1'~8~77 hydrotreater, or deposited on the hydrotreating catalyst.
This may result in superior operation in the catalytic dewaxing unit, and a longer operational life.
For some high sulfur oils it is better to conduct dewaxing before the hydrotreating step. As discussed in U.S.
Patent 3,894,938, the advantages of dewaxing before hydrotreating are disclosed.
Any conventional hydrotreating catalyst and processing conditions may be used.
Preferably the hydrotreating process uses a catalyst containing a hydrogenation component on a support, preferably a non-acidic support, e.g., Co-Mo or Ni-Mo on alumina.
The hydrotreater usually operates at relatively low temperatures, typically from 150 to 350C, and preferably 15 at temperatures of 200 to 300C.
The hydrotreating catalyst may be disposed as a fixed, fluidized, or moving bed of catalyst, though down flow, fixed bed operation is preferred because of its simplicity. When the hydrotreating catalyst is disposed as a fixed bed of catalyst, the liquid hourly space velocity, or volume per hour of liquid feed measured at 0C per volume of catalyst will usually be in the range of about 0.1 to 10, and preferably about 1 to 5. In general higher space velocities or throughputs require higher temperature operation in the reactor to produce the same amount of hydrotreating.
The hydrotreating operation is enhanced by the presence of hydrogen, so typically hydrogen partial pressures 1281~77 of l to 100 atmospheres, absolute are employed. Hydrogen can be added to the feed on a once through basis, with the hydrotreater effluent being passed directly to the wax isomerization zone, or vice versa, as disclosed in U.S.
3,894,938.
If hydrotreating is done first, the hydrotreater effluent is preferably cooled, and the hydrogen rich gas phase recycled to the hydrotreater. Cooling of hydrotreater effluent, and separation into vapor and liquid phases promotes removal of some of the nitrogen and sulfur impurities which would otherwise be passed into the catalytic dewaxing zone.
Other suitable hydrogenation components include one or , more of the metals, or compounds thereof, selected from Groups Il II, III, IV, V, VIB, VIIB, VIII and mixtures thereof of the Periodic Table of the Elements. Preferred metals include molybdenum, tungsten, vanadium, chromium, cobalt, titanium, iron, nickel and mixtures thereof, e.g., Co-Mo or Ni-Mo.
Usually the hydrotreating metal component will be present on a support in an amount equal to 0.1 to 20 weight 20 il percent of the support, with operation with 0.1 to 10 weight percent hydrogenation metal, on an elemental basis, giving good !
i results.

The hydrogenation components are ùsually disposed on a support, preferably an amorphous support such as silica, 2~5 alumina, silica-alumina, etc. Any other conventional support ; , ~
material may also be used. It is also possible to include c~

the support an acid acting component, such as an acid exchan~
clay or a zeolite.

,~

~ .

It is also possible to cascade dewaxing and desulfurization as described in U.S. Patent 4,394,249.
HYDROC;ENATION/DEHYDROGENATION COMPONENT OF DEWAXING CATALYST

An essential part of the process of the present invent:ion is incorporation of a hydrogenation/dehydrogenation component into the dewaxing catalyst.
The hydrogenation/dehydrogenation component is believed to promote hydroisomerization activity in addition to the shape selective cracking activities that occur with ZSM-ll. This combination of activities gives higher activity, better selectivity and lower pour point product than can be achieved with ZSM-5 catalysts.
The hydrogenation/dehydrogenation component may be added by ion exchange or impregnation, or any other method known to the art of incorporating hydrogenation/dehydrogenation components in a support, the support in this instance being either ZSM-ll alone or in admixture with a refractory inorganic oxide binder. Suitable hydrogenation/dehydrogenation components may be selected from one or more of the metals, or compounds thereof, selected ;~ ~ from Groups II, III, IV, V, VIB, VII~, VIII and mixtures thereof of the Periodic Table of the Elements. Preferred metals include molybdenum, tungsten, vanadium, chromium, cobalt, titanium, iron, nickel and mixtures thereof, e.g., 5~ `Co-Mo or Ni-Mo.

The metal component may be incorporated into the catalyst by impregnation, by ion exchange or by other means by contacting either the catalyst or a component thereof with a solution of a compound of the metal in an appropriate amount necessary to provide the desired concentration within the scope of the invention. The metal component may be incorporated either in any step during preparation of the catalyst`or after the finished catalyst has been prepared. A
preferred manner of incorporation is to ion-exchange a crystalline aluminosilicate and then compositing the ion-exchanged product with a porous matrix. Also useful is the ion-exchanging or impregnation of siliceous solids or clays. Suitable metal compounds include the metal halides, preferably chlorides, nitrates, ammine halides, oxides, sulfates, phosphates and other water-soluble inorganic salts;
and also the metal carboxylates of from 1 to 5 carbon atoms, alcoholates. Specific examples include palladium chloride, chloroplatinic acid, ruthenium penta-ammine chloride, osmium chloride perrhenic acid, dioxobis (ethylenediamine) rhenium (V) chloride, rhodium chloride and the like. Alternatively, an oil-soluble or oil-dispersable compound of the metal may be added in suitable amount of a hydrocarbon feedstock, such as a gas oil charge stock, for incorporation in the catalyst - as the charge is cracked. Such compounds include : ~ :

: ~ :

1~81~77 metal diketonates, carbonyls, metallocenes, olefin complexes of 2 to 20 carbons, acetylene complexes, alkyl or aryl phosphine complexes and carboxylates of l to 20 carbons. Specific examples of these are platinum acetylacetonate, tris (acetylacetonato) rhodium (III), triiodoiridium (III) tricarbonyl, -cyclopentadienylrhenium (I) tricarbonyl, ruthenocene, -cyclopentadienylosmium (I) dicarbonyl dimer, dichloro (ethylene) palladium (II) dimer ( -cyclopentadienyl) (ethylene) rhodium (I), diphenylacetylenebis (triphenyl-phosphino) platinum (O), bromomethylbis (triethylphosphino)palladium (II), tetrakis (triphenylphosphino)palladium (O), chlorocarbonylbis(triphenylphosphino) iridium (I), palladium ;l acetate, and palladium naphthenate. i ~i The hydrogenation/dehydrogenation component will also, 15 , to a certain extent, serve as a hydrogenation/dehydrogenation promoter but that is not the primary purpose of adding this component.
There will be a small amount of hydrotreating, i.e., removal of any sulfur and nitrogen compounds present, due to 20~l the presence of the e.g., platinum group component and this is a beneficial, though unintended result. The hydrogenation/
dehydrogenation component is essential to promote hydroisomerlzation of long chain normal or slightly branched paraffins to more highly branched paraffins. This 25~ hydroisomerization converts the waxy long chain paraffins into materials which are compatible with the fuel oil product, ; permitting increased yields of fuel oil when using the process of the present invention. It is much more beneficial, from a 1281~77 liquid yield standpoint, to hyaroisomerize long chain paraffins to other liquid products than it is to simply hydrocrack these materials.
The amount of the hydrogenation/aehyarogenation component a~ed to the catalytic dewaxing catalyst is not narrowly critical an~ may range from about 0.01 to 3~ weight percent, calculate~ as the elemental metal base~ upon the weight of the entire catalyst.
Operation with O.û5 to 5 weight percent, calculated as the elemental metal of a Pt group component gives good results, with the preferred amount of Pt group metal component being equal to 0.1 to 2.0 weight percent.

EXAMPLES
15 l ¦ Example 1 (Prlor Art) This illustrates the dewaxing of distillate using a conventional catalyst, a steamed O.9X Ni - 65% ZSM-5/35X
A1203 (Ni by exchange). The ZSM-5 had a SiO2:Al203 20 I ratio of about 70.
Commercially-prepared, extruded catalyst was -laboratory steamed 6 hours at 900F. The steamed catalyst was i used to hydrodewax feed having the properties shown in Table I.
:

1'~81~77 Table I

Gas Oil A Gas Oil ~ Gas Oil C
.

Gravity, API 35.9 24.8 28.0 Pour Point, F 75 65 85 Cloud Point, F 100 88 KV ~ 40C, cs 7.07 21.64 23.77 KV ~ lû0C, cs 2.186 4.169 4.4~3 Sulfur, wt ~ û.O9 2.25 0.84 ~itrogen, ppm 18û 46û 560 Hydrogen, wt ~ 13.65 12.60 13.18 Bromine No. û.8 4.3 2.1 Carbon Residue by MCRT, % 0.02 0.01 0.01 Vacuum Distillation - D1160 5 Vol X Distillated 531 703 693 551 714 726 `

i 40 641 749 782 15 ' 50 668 763 794 i 80 744 803 823 ¦ End Point 875 837 870 !
The catalyst was disposed as a fixed bed of catalyst in a reactor.
Reaction conditions and product properties are : reported in the table, after Example 2.
I
Example 2 (Invention) The catalyst used in thls study was prepare~
by flushing unsteamed HZSM-ll, 65 wt ~ ZS~-ll (with a silica to alumina ratio, on a molar basis, of about 70) and 35 wt % alumina in 14-25 mesh, with C02 for a few i ' ~, 1-~81~77 minutes, followed by chloroplatinic acid-impregnation to 0.5%
platinum by weight. The platinum ZSM-ll catalyst was loaded into the same fixed bed reactor used in Ex. I and reduced in situ at 400 psig of hydrogen and 900F for one hour. Light S neutral stock was then pumped into the reactor along with hydrogen after the reactor temperature was lowered to the deaired setting. After five days on stream with light neutral stock, the feed was switched to bright stock. These runs were ~a~e at 540-585F, 400 psig of H2, 2500 SCF/bbl, and 0.75-1.0 LHSV. After five days, the feed was changed to Gas Oil A. The runs were conducted at 700-750F, 400 psig of H2, 2000 SCF/bbl, and 1.0 LHSV. The dewaxed distillate products have a pour point lower than -65F.
The properties of dewaxed distillate products 15 ~, processed with the Pt/ZSM-11 catalyst (invention) are compared to Ni-ZSM-5 ~prior art), in the following Table II.

TABLE II
ProPertv comParison of Dewaxed Distillate SteamedUnsteamed ~1 Ni-ZSM-5 Pt-ZSM-ll ; I ~eactor Temp., F 700 700 744 Pressure, psig 400 400 400 ¦ LHSV
H2 Circ., SCF/bbl 2000 2000 2000 Days on Stream 15 13 14 1 25 Pour Point, F 20 LT -65 LT -65 Product Selectivity, wt %
l-C2 0.2 1.1 1.1 C3 5.3 12.7 11.6 C4 9.3 7.1 6.4 C5-330F 29.2 20.2 22.3 330F+ 56.0 58.9 58.6 . ~ ~

~ -21-~8~

At 700F, the product from ZS~-ll has a pour point lower than -65F while that from ~i-ZSM-5 has a 20F pour, indicating that Pt-ZSM-ll is more active than ~i-ZS~-5 for distillate aewaxing.
~oth catalysts gave the almost same distillate yields at 700F, as shown in the table. For distillate dewaxing, the lower the pour point, the lower the yield. Removal of waxy components to reduce pour point usually results in removal of product, and lower yields. Consequently, the distillate yiela with Pt-ZSM-ll should be much higher than 60 wt ~ if the reactor temperature was dropped to give a pour point of 20F.
Pt-ZS~-ll is far more selective than ZSM-5-~ Lxample 3 (Invention) 15 I The catalyst of Example 2 was thereafter used for dewaxing Gas Oil B with results reported in Table III.

Table III
PropertY Comparison of Dewaxed Distillate 20 l SteamedUnsteamed Ni-ZSM-5 Pt-ZSM-ll Reactor Temp. F 700 625 Pressure, Psig H2 400 LHSV
~ H2 Circ., SCF/bbl 2000 2000 : 25 ! Pour Point, F
:
Product Selectivity, wt ~
C4 4.0 4.0 C5-330F 9.0 8.7 ;1~ 330F+ 87.0 87.3 ~ .
~ ~.

lX~ 77 For Gas Oil B, the Pt/ZS~-ll catalyst is 75F more active than steamed ~i-ZSM-5 while the selectivities are comparable.
Example 4 (Invention) The catalyst of Example 3 was thereafter used for dewaxing Gas Oil C. The results are shown in Table IV:

Ta~le IV
Property Comparison of Dewaxed Distillate Steamed Unsteamed Ni-ZS~-5 Pt-ZS1~1-ll Reacto r Temp. F 710 655 Pressure~ Psig H2 LHSV 1 ` 1 H2 Circ., SCF/bbl 2000 2000 j Pour Point, F o o ¦ Prodùct Selectivity, wt X
i C~ 6.6 5.7 C5-330F 11.4 9.8 ! 3300F+ 82.0 84.5 For Gas Oil C, the Pt/ZSM-ll catalyst offers a catalyst activity advantage of 55F over steamed Ni-ZSM-5. In addition, Pt/ZSM-ll improves the 330F+ selectivity by 2.5%.
Best Mode If we were building a catalytic dewaxing unit to reduce the pour point of distillate today, we would use a ~catalyst comprising 65 weight percent ZSI~1-11 and 35 weight percent alumina and it would Contain about 0.5 weight percent Pt added by impregnation. The ZSI~I-ll use~ would have a SiO2:A1203 ratio of about 70 and would not be steamed.
The Pt would be calcined to fix it on the support, then reducea ~1 !
with hydrogen to the elemental state.

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The catalyst would be disposed as a fixed bed in a eeactor operated at the following conditions: 500-800F under Ihydrogen pressure of 250-500 psig and with hydrogen circulation of about 1500-2500 SCF/bbl. The preferred space velocity would be about 0.5-2.0 LHSV.

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Claims (9)

1. A process for reducing the pour point of a waxy hydrocarbon fuel oil which comprises contacting said oil at catalytic dewaxing conditions including a temperature of about 450° to 850°F in a reaction zone in the presence of hydrogen with a catalyst comprising ZSM-11 and a hydrogenation/ dehydrogenation component other than a platinum group metal alone to produce a dewaxed fuel oil with reduced pour point.

2. Process of claim 1 wherein said hydrogenation/ dehydrogenation component is selected from the group of metals of Groups II, III IV, V, VIB, VIIB, VIII, other than platinum group, and mixtures thereof.

3. Process of claim 1 wherein said catalyst contains about 0.01 to 30 weight percent hydrogenation/dehydrogenation component, calculated on an elemental metal basis.

4. Process of claim 1 wherein catalytic dewaxing conditions include a hydrogen partial pressure of about 15 to 2000 psia, a ratio of hydrogen to hydrocarbon of about 500 to 5000 SCF/bbl and a liquid hourly space velocity of about 0.5 to 5.

5. Process of claim 1 wherein said catalyst comprises ZSM-11 and a refractory inorganic oxide binder.

6. Process of claim 5 wherein said refractory inorganic oxide binder is alumina, silica or silica alumina.

7. Process of claim 1 wherein said ZSM-11 has a SiO2:Al2O3 ratio in excess of 15:1.

8. Process of claim 1 wherein said catalyst comprises 50 to 80 weight percent ZSM-11 and 50 to 20 weight percent alumina.

9. A process for reducing the pour point of a waxy hydrocarbon fuel oil with a relatively high pour point which comprises contacting said oil at catalytic hydrodewaxing conditions including a temperature of about 450 to 850°F, hydrogen partial pressure of 25 to 1000 psia, a ratio of hydrogen to hydrocarbon of 500 to 5000 SCFB and a liquid hourly space velocity of 0.5 to 5 in a reaction zone containing a fixed bed of catalyst comprising ZSM-11 and 0.01 to 30 weight percent hydrogenation/dehydrogenation group component other than a platinum group metal alone, on an elemental metal basis, to produce a dewaxed fuel oil product with a reduced pour point.