CA1274204A - Cascade dewaxing process - Google Patents

Abstract

Abstract Hydrocarbon feedstocks are dewaxed in a cascade process by contacting a waxy feedstock with a large pore crystalline zeolite catalyst and then with a medium pore crystalline zeolite catalyst. Preferably both contactings are performed in the presence of added hydrogen, each zeolite being associated with a hydrogenation/
dehydrogenation component: the first contacting may function as a hydroisomerisation step. In certain applications a preferred large pore zeolite is zeolite beta. In certain applications a preferred medium pore zeolite is ZSM-11. Some degree of interstage separation can be adopted.

Description

~'7~
F-3 1 8 2+ - 1-CASCADE DEWAXING PROCESS

This invention relates to a cascade dewaxing process using a large pore crystalline zeolite as catalyst in a first contacting with a feedstock and a medium pore crystalline zeolite catalyst in a subsequent contacting.
Refining petroleum feedstocks to obtain lubricating oils which may function effectively in diverse environments has become a highly developed and complex art. Although the broad principles involved in refining are qualitatively understood, the art is encumbered by `10 quantitative uncertainties which require a considerable resort to empiricism in practical refining. Underlying ; these quantitative uncertainties is the complexity of the molecular constitution of lubricating oils. Because ~ ~ lubricating oils for~the most part are based on~petroleum -~ 15 fractions boiling above about 450F (232C), the hydrocarbon constituents are of high molecular weight and display extraordinary diversity of structure. This complexity and its consequences are referred to in well-known treatises, such as, for examples, "Petroleum Refinery Engineering", by W.~L. Nelson, McGraw-Hill Book ~Companyj Inc., New York, NY, 1958 (Fourth Edition). For -purposes of this invention,~ lubricating oil or lube oil is th~at part of a hydrocarbon feedstock having a boiling point of 650E ~343C) or higher as determined by ASTM D-~ 97 test method.
In general, the basic premise in lubricant r~efining is that a suitable crude oi1, as shown by ~Z~
F-3182~ -2-experience or by assay, contains a quantity of lubricant stock having a predetermined set of properties~ such as, for example, appropriate viscosity, oxidation stability, and maintenance of fluidity at low temperatures. The process of refining to isolate ~hat lubricant stock consists of a set of subtractive unit operations which removes the unwanted components. The most important of these unit operations include distillation, solvent refining and dewaxing, which basically are physical separation processes in the sense that if all the separated fractions were recombined, one would reconstitute the crude oil.
A refined lubricant stock may be used by itself, or it may be blended with another refined lubricant stock having different propertieæ. Prior to use it may be compounded with one or more additives which function, for example, as antioxidants, extreme pressure additives, V.I.
improvers.
For the preparation of a high grade di~tillate lubricating oil stock, it is known to vacuum distill an atmospheric tower reaiduum from an appropriate crude oil as the first step. This step provides one or more raw stocks within the boiling range of about 450F to 1050F
(232-566C). After preparation of a raw stock of suitable boiling range, it is extracted with a solvent, e.g., furfural, phenol, sulfolane, or chlorex, which is selective for aromatic hydrocarbons, and which removes undesirable components. The raffinate from solvent refining is then dewaxed, for example, by admixin~ with a solvent, such as a blend of methylethyl ketone and toluene. The mixture is chilled to induce crystallization of the paraffin waxes, which are then separated from the raffinate. Sufficient quantities of wax are removed to provlde the desired pour point for the raffinate.

~Z79~

F-3182+ -3-Other processes, such as hydrofinishing or clay percolation, may be used if needed to reduce the nitrogen and sulfur content or improve the color of the lubricating oil stock.
Viscosity index tv.I.) is a ~uality parameter of considerable importance for distillate lubricating oils to be used in automotive engines and aircraft engines subject to wide variations in temperature. This index indicates the degree of change of viscosity with temperature. A
high V.I. of 100 indicates an oil that does not tend to become viscous at low temperature or become thin at high temperatures. ~easurement of the Saybolt Universal Viscosity of an oil at 100F (38C) and 210F (99C), and referral to correlations, provides a measure of the V.I.
of the oil. For purposes o~ the present invention7 whenever V.I is referred to, it is meant the V.I. as noted in the Viscosity Index tabulations of the ASTM (D567), published by ASTM, 1916 Race Street, Philadelphia, PA, or equivalent.
In recent years, catalytic techniques have become available for dewaxing of petroleum stocks. A
process of that nature developed by British Petroleum is described in The_Qil_a~_G3s_~ou~gal, dated January 6, 1975, at pages 69-73.
US-A-3,700,585 describes a process for catalytic dewaxing with a catalyst comprising zeolite ZSM-5. Such a process combined with catalytic hydrofinishing is described in US-A-3,894!936. US-A-3t956,102 discloses a particular method for dewaxing a petroleum distillate with a ZSM-5 catalyst. US-A-3,769,202 teaches catalytic conversion of hydrocarbons using as a catalyst two different crystalline silicate zeolites, one having a pore size greater than 8 Angstroms and the other having a pore size less than 7 Angstroms, and that a conventional ~279~2~
F-3182~

hydrogenation/dehydrogenation component may be added, in an amount from about 0.01 to about 30 wt. ~.
It remains deslrable to increase lube yield, raise product viscosity index (V.I.) ancl to improve catalyst stahility and flexibility in catalyst regeneration.
According to the invention a process for dewaxing a hydrocarbon feedstock comprises, first, contacting said feedstock at elevated temperature with a catalyst comprising a crystalline zeolite having a constraint index less than 2, possessing acidic sites and associated with a catalytically effective quanti~y of a component possessing hydrogenation/dehydrogenation activity, and, second, contacting at least the majority of the effluent from said first contacting, at elevated temperature, with a catalyst comprising a crystalline zeolite having a constraint index greater than 2, possessing acidic sites and associated with a catalytically effective quantity of a component possessing hydrogenation/dehydrogenation activity, and recovering a normally liquid hydrocarbon product of reduced wax content relative to said feedstock. The first and/or second contacting is preferably carried out in the presence of added hydrogen, each hydrogenation/dehydrogenation component comprising a metal of Group VI, VII and/or VIII
of the Periodic Table. When that metal is a Group VIII
noble metal it usually constitutes 0.1 to 5, suitably 0.3 to 3, wt. ~ of the catalyst with which it is associated.
When it is a non-noble ~etal it usually constitutes 0.3 to 25 wt. % of the catalyst with which it is associated.
The process is typically conducted at an overall liquid hourly space velocity~between 0.1 and 5, preferably between 0.2 and 3Ø Each contacting may be carried out at a temperature in the range 232 to 371C l450 to 700F)~
.

~7~
F-3132~ _5_ a liquid hourly space velocity of 0.1 to 10 and a pressure no greater than 70 bar (1000 psig), advantageously below 42.5 bar (600 psig), even more advantageously below 28.5 bar (400 psig). The preferred individual stage liquid hourly space velocity is 0.2 to 6Ø The usual form of reactor for the first and/or second contacting is a fixed, slurry or moving bed unit.
Large pore zeolites for use in the first contacting embrace zeolite Y, ultrastable zeolite Y, dealuminised zeolite Y, ZSM-3, ZSM-18 or ZSM-20, medium pore zeolites for use in the second contacting, zeolite ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48 or TMA Offretite.
In many applications the large pore zeolite of choice is zeolite beta, and in such cases the hydrogenation/
dehydrogenation component associated with the zeolite will usually be platinum. The zeolite of choice for the second contacting will in many applications be ZSM-5, or on occasion ZSM-ll, usually associated with nickel.
The feedstock contains waxy components which are normal and/or slightly branched paraffins, and the majority of it may be expected to have a boiling point above 250C. The process may advantageously be controlled so that the normally liquid effluent from the first contacting has a pour point less than that of said feedstock but no less than 50F ~10C), optionally no less than 70F (21C). In a particular embodiment where the feedstock is a solvent-refined raffinate the activity of the zeolite employed in the first contacting may advantageously be reduced prior to the contacting, and optionally a 650F- (343C-) fraction may be removed from the effluent of the first contacting before the second contacting is performed~
Of the many ways in which the invention can be put into practice some are of particular technical merit.

1~ 7 ~
F-3182+ -6-Thus, in one favoured embodiment, the invention concerns a dewaxing process which comprises:
(a) passing a solvent-refined raffinate feedstock over a large pore crystaline silicate zeolite having a Constraint Index less than 2, a silica-to-alumina mole ratio of at least 10, acidic sites~ and having hydrogenation/dehydrogenation activity in the presence of hydrogen at a temperature between 450F (232C) and 700F
(371C), a pressure of about 400 psig (28.6 bar~, a hydrogen feed rate of about 2500 SC~ H2/bbl (445 m3/m3) and a LHSV between 0.2 and 6.0;
(b) passing the entire effluent from step (a) over a medium pore crystalline silicate zeolite having a Constraint Index no less than 2 and having hydrogenation/
dehydrogenation actlvity, in the presence of hydrogen at a temperature between 450F (232C) and 700F (371C), the temperature of step (b) being the same or different from the temperature of step (a3, a pressure of about 400 psig, a hydrogen feed rate of about 2500 SCF H2/bbl and a LHSV
between 0.2 and 6.0; and : (c) recovering from the effluent of step (b) a hydrocarbon feed with reduced wax content.
This embodiment may be regarded as directed to a cascade catalytic dewaxing process wherein a solvent-refined raffinate feedstock is sequentially passed over a first reaction zone containing a zeolite from the group having the structure of TEA Mordenite, Zeolite Y, Deal Y, :
USY, REY, Zeolite Beta, ZSM-4t ZSM~20, H-Zeolon and : amorphous alumina, and having a silica/alumina ratio greater than 10, and having associated therewith acidic sites and 0.1 tD 25 Wt. ~ of a hydrogenationj dehydrogenation component selected from the metals of ; Groups VI, VII,~ and VIII, passing the entire effluent from the first reaction zone into a second reaction zone ~' ~LZ7~
F-3182+ -7-containing a medium pore zeolite having the structure of ZSM-5, ZSM-ll, ZSM-12, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, TMA Offretite and Erionite, and containing from 0.1 to 25 wt. % of a hydrogenation/dehyd.rogenation component selected from the group of Group VI, VII and VIII and mixtures thereof, to produce a hydrocarbon liquid product with a reduced wax content;
It may also be regarded as directed to a dual catalyst cascade dewaxing process involving intermediate separation, comprising:
ta) passing a solvent-refined raffinate feedstock over a cataylst comprising a crystalline silicate zeolite having a Constraint Index less than 2, having acidic sites, and having hydrogenation/
dehydrogenation activity;
(b) separating the product of step (a) .into a 650F- fraction and a 650F~ fraction (650F=343C); and (c) passing at least a majority of the 650F+
fraction over a zeolite having a Constraint Index between

2 and 12 and having hydrogenation/dehydrogenation activity.
The intermediate-separation feature of this embodiment may also be expressed as a process comprising:
(a) passing a hydrocarbon feedstock containing long chain normal paraffins and long chain slightly branched parffins, wherein at least a majority of said feeds~ock has a boiling point in excess of 482F (250C), over Zeolite Beta, said Zeolite Beta having catalytically effective amounts of hydrogenation/dehydrogenation compon.ent, in the presence of hydrogen at a temperature between 450 and 750F ~232-399C), a pressure of about 400 psig, a hydrogen feed rate of about 2500 SCF H2/BBL
and a L~ISV between 0.2 and 6.0;
: (b) separating the product of step (a) into a 650F- fraction and a 650F+ fraction; and F-3182~ -8 (c) passing the 650F+ fraction from step (a) - over a zeolite selected from the group having the structure of ZSM-5, ZSM-ll, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and TMA Offetite, said zeolite having catalytically effective amounts of hydrogenation/
dehydrogenation component in the presence of hydrogen at a temperature between 500 and 700OF ~260-371C), a pressure of about 400 psig, a hydrogen feed rate of about 2500 SCF
H2/BBL and a LHSV between 0.2 and 6Ø

B~ief-Desçr~ap~lQ~-Q~-5hg-Dr3wi~gs Fig. 1 compares ~iscosity index to pour point for a single zone ~nd a cascade reactor system dewaxing a solvent-refined raffinate; and Fig. 2 illustrates the effect of days onstream to reactor temperature for both a single zone and a cascade reactor system.
Fig. 3 illustrates the effect of the presence of interstage separation on the temperature of the second stage reactor with regard to days onstreamO

If Zeolite Beta is place in the first stage reactor, it is optional, and in fact preferred in the embodiment, to discard the reaction product of the first stage for the first 1 or 2 days after fresh catalyst has been added to the first reactor. It is believed that the product of the chargestock as it passes through the highly ~ active fresh catalyst of the first reactor, will contain ~ poisons which will damage the shape-selective catalyst in the second reactor. After a period of 1 or 2 days onstream, the frésh catalyst will have had a chance to age and stabilize in order to produce a chargestock product which will be suitable for feeding to the second stage o~:~
F-3182+ -9_ catalyst. Other methods of aging the catalyst of the first reactor are known to the artt such as, for example, steaming the catalyst.
The interstage separation step o~fers a variety of advantages over and above those disclosed by a cascade S reaction system without interstage separationO It is speculated that the interstage separaion process rids a variety of poisons from the chargestock. The 650-F stock is not considered a lube stock, and contains such components as alkyl aromatics, nitrogen components~ and other "poisons". Some of these products are useful for the production of naphthas, gasoline and distillates.
However, they may damage the effectiveness of the second and subsequent stages of a cascade reactor process.
Another advantage of the interstage separation step is that it lowers the start of cycle tSOC) and line out ~LO) temperatures. The SOC temperature is the temperature at which catalysis is initiated. The LO
temperature is that temperature where the activity of the catalyst beyins to level out. It is well known in the field of catalytic conversion that a fresh catalyst exhibits hiyh activity and aging during the first part of the catalytic conversion process. After a certain amount of time, generally about 2 to 12 days, the activity and the aging process of the catalyst begin to settle or line out. By ridding the chargestock of the 650-F component, the SOC and kO temperatures are much lower. This will be considered more directly with respect to the exa~ples.
A f~rther advantageous embodiment of the invention concerns a dual catalyst cascade dewaxing process comprising:
(a) passing a hydrocarbon feedstock containing waxy components comprising normal paraffins and/or slightly branched chain paraffins over a catalyst F-318~+ -10~

comprising a crystalline silicate zeolite having a Constraint Index less than 2, having acidic sites, and having associated therewith a catalytically efective amount of hydrogenation/dehydrogenation component;
(b) passing at least a majority of the normally liquid hydrocabon recovered from step (a) over a zeolite having the structure of ZSM-ll and a catalytically effective amount of a hydrogenation/dehydrogenation component; and (c) recovering a normally liquid hydrocarbon product having a reduced wax content relative to the feedstock, from the product of step ~b).
The embodiment may be defined in greater detail . as comprising:
(a) passing a hydrocarbon feedstock containing long chain normal paraffins and long chain slightly branched paraffins, wherein at least a majority of the feedstock has a boiling point in excess of 48~F (250C~, over a large pore crystalline silicate zeolite having a Constraint Index less than 2, a silica to alumina mole ratio of at least 10, acidic sites, and having catalytically effective amounts of a hydrogenation/
dehydrogenation component in the presence of hydrogen at a temperature between 450F (232C) and 700F (371C), a pressure of about 400 psig (28.6 bar), a hydrogen feed rate of about 2500 SCF ~2/bbl (445 m3/m3~ and a 1~SV
between 0.2 and 6~0;
(b) passing the entire effluent from step (a) over zeolite ZSM-ll, having catalytically effective amounts of a hydrogenation/dehydrogenation component, in the presence of hydrogen at a temperature between 500F
(260~C) and 700F (371C), the temperature of step (b) being the same or different from the temperature o step (a), a pressure of about 400 psig, a hydrogen feed rate of :~27~

F 3182+

about 2500 SCF H2/bbl and a LHSV between 0.2 and 2.0; and ~c) recovering from the effluent of step ~b) a hydrocarbon feed wi~h reduced wax content.
In practice this embodiment will frequently take the form of a cascade catalytic dewaxing process wherein a hydrocarbon feedstock with a boiling point in excess of 482F (250C) and containing normal paraffins and slightly branched chain paraffins is sequentially passed over a first reaction zone containing a zeolite from the group having the structure of Mordenite, Zeolite Y, Zeolite Beta, ZSM-4 and ZSM~20, and having a silica/alumina ra~io greater than 10, and having associated therewith acidic sites and 0.1 to 25 wt. % of a hydrogenation/
dehydrogenation component selected from the metals of Groups VI, VII and VIII, passing the entire effluent from the first reaction zone into a second reaction zone containing a medium pore zeolite having the structure of ~ ZSM-ll, and containing from 0.1 to 25 wt. % of a ; hydrogenation/dehydrogenation component selected from the group of Group VI, VII and VIII and mixtures thereof, to produce a hydrocarbon liquid product with a reduced wax content In the first stage, the feedstock is hydroisomerized over the high silica, large pore zeolite catalyst, followed by shape selective dewaxing in the second sta~e over ZSM-ll. It is believed that a cascade relationship of the large pore zeolite and ZSM-ll, in the right proportion, offers superior dewaxing activities and lube yield, higher V.I. r improved catalyst stability in the second stage and flexibility in catalyst regeneration in comparison with the prior art~
ZSM-ll has a Constraint Index between 6 and 8.7 and an effective pore size of generaily not greater than about 7 Angstroms, so as freely to sorb normal hexane. In many process applications it has shown little or no ., F-3182+ =12-difference from ZSM-5. However, as reported in ~3r3d3Y
Disc _Çhem~_SQc~, 72, p. 353 ll982), ZSM-ll has shown high hydroisomerization activity where ZSM-5 exhibits only shape-selective cracking. Additionally, the structure of ZSM-ll has intersecting linear channels, rather than the intersecting linear and tortuous channels of 2SM-5.
Although conventional dewaxing catalysts generally utilize a zeolite having the structure of ZSM-5, it will be seen in the Exmaples which follow that the ZSM-ll can be more active and selective for dewaxing than ZSM-5.
Although it is not necessary, the acidity o the ZSM-ll zeolite will usually be very similar to the acidity of the large pore zeolite. If it is desired, or reasons of economy or otherwise, to use a noble metal promoter in association with a large pore zeolite, and a base metal promoter in association with ZSM-ll, it may be beneficial to operate with different acidities or silica/alumina ratios in the large pore æeolite and ZSM-llo sest results will be obtained when the acidity of the ZSM-ll zeolite is matched to the strength and amount of the hydrogenation/dehydrogenation component incorporated in the ZSM-ll zeolite.
It will usually be beneficial to incorporate the ZSM-ll zeolite into a conventional matrix. It is possible, and preferable, ~to operate with the same matrix for both the ZSM-ll zeolite and the large pore zeolite.
In its simplest form, a cascade operation in this embodiment may be achieved by using a large down flow reactor, wherein the lower portion contains the catlyst comprising the ZSM-ll zeolite and the upper portion contains the catalyst comprising the large pore ~eolite.
Two or more reactors in series may also be used, e.g., a three-reactor system may be used. The first one or two reactors in series would contain the relatively F-3182~ -13-large pore zeolite, while the last, and optionally all or a portion of the second reactor would contain the ZSM-ll zeolite. Both stages, i.e., the large pore zeolite reactor and the ZSM~ll zeolite reactor are operated in the presence of hydrogen and under the same pressure.
According to yet a further embodimen the invention is directed to a cascade-catalytic dewaxing process comprising:
(a) passing a hydrocarbon feedstock containing waxy components selected from a group of normal paraffins and slightly branched chain paraffins over a catalyst comprising a crystalline silicate zeolite having a Constraint Index less than 2, having acidic sites, and having associated therewith a catalytically effective amount of a hydrogenation/dehydrogenation component under conditions such that the hydrocarbon product of step (a) has a pour point no less than about +50F;
~b) passing at least a majority of the normally liquid hydrocarbon recovered from step ~a) over a medium pore crystalline silicate zolite, having acidic sites and a catalytically effective amount of a hydrogenation/
dehydrogenation component; and (c) recovering a normally liquid hydrocarbon product having a reduced wax contant relative to the feedstock, from the product of step (b).
In practice this embodiment usually takes the form of:
~a) passing a hydrocarbon feedstock containing long chain normal paraffins and long chain slightly branched paraffins, wherein at least a majority of the feedstock has a boiling point in excess of 482F ~250C), over a large pore crystalline silicate zeolite having a Constrain Index less than 2, a silica to alumina mole ratio of at least 10~ acidic sites, and having 1 Z~ 4 2~a4 F-3182~ -14-catalytically effective amounts of a hydrogenation/
dehydrogenation component in the presence of hydrogen at a temperature between 5000F (260C) and 700F ( 371C), a pressure no greater than 600 psig (42.5 bar) and a LHSV
between 0~2 and 2.0 such that the hydrocarbon liquid product of step (a) has a pour point no less than +70F
(21C);
(b) passing the entire effluent from step ~a) over a medium pore zeolite having a silica to alumina ratio in excess of 10, acidic sites associated therewith, lo and having catalytically effective amounts of a hydrogenation/dehydrogenation component in the presence o~
hydrogen at a temperature between 500F (260C) and 700F
(371C) t the temperature of step (b) being the same or different from the temperature of step (a), a pressure of no greater than 600 psig and a LEISV between 0.2 and 2~0;
and (c) recovering from the effluent of step (b~ a hydrocarbon feed with reduced wax content.
This embodiment may also be regarded as directed : to a cascade catalytic dewaxing process wherein a hydrocarbon feedstock with a boiling point in excess of 482F (250C) and containing normal paraffins and slightly branched chain paraffins is sequentially passed over a first reaction zone containing a zeolite from the group having the structure of Mordenite, Zeolite Y, Zeolite Beta, ZSM-4 and ZSM-20, and having a silica/alumina ratio greater than lO, and having associated therewith acidic sites and 0.1 to 25 wt. % of a hydrogenation/
dehydrogenation component selected from the metals of ~roups VI, VII and VIII, passing the entire effluent from the first reaction zone into a second reaction zone ~ containing a medium pore zeolite selected from the group : having the structure of ZSM-5 and ZSM-ll, having a silica F-3182+ -15-to alumina ratio greater than 10 and containing from 0.1 to 25 wt. % of a hydrogenation/dehydrogenation component selected from the group of Group~ VI, VII and VIII and mixtures thereof, to produce a hydrocarbon liquid product with a reduced wax content.
Reverting to its generality, the present invention is preferably arranged 1~ a two-stage cascading relationship whereby, in the first stage, the feedstock is hydroi~omerized over a high silica large pore zeolite catalyst, followed by shape selective dewaxing in the lo second stage over a medium pore zeolite catalyst. It is believed that a cascade relationship of the large pore zeolite and the medium pore zeolite, in the right proportion, will offer superior dewaxing activities and lube yield, higher V.I., improved catalyst stability in the second stage and ~lexibility in catalyst regeneration than the lube dewaxing catalysts of the prior art.
The present process may be used to dewax a variety of feedstocks ranging from relatively light distillate fractions up to high boiling stocks, such as whole crude petroleum, reduced crudes, vacuu~ tower residua, propane deasphalted residua, e.g., brightstock, cycle oils, FCC tower bottoms, gas oils, vacuum gas oils, deasphalted residua and other heavy oils. The feedstock will normally be a Clo+ feedstock since lighter oils will usually be free of significant quantities of waxy components. However, the process is also particularly useful with waxy distillate stocks, such as gas oils, kerosenes, jet fuels, lubricating oil stocks~ heating oils, hydrotreated oil stock, solvent-refined raffinate, urfural-extracted lubricating oil stock, and other distillate fractions whose pour point and viscosity need to be maintained within certain specification limits.
Lubricating oil stocks, for example, will generally boil 2~ 4 F-3182~ ~16-above 450F (230C), and more easily above 600F (313C~.
The process is also useful for solvent refined neutral oil and hydrocracked oil produced by the catlytic hydrocracking or hydrotreating of hydrocarbon feedstocks boiling about 650F (343C~.
The catalysts used according l:o the invention are zeolites, a term employed here~n to designate not only aluminosilicates having a crystal lattice made up of SiO4 and A104 tetrahedra cross-linked by the sharing of oxygen atoms but also such structures from which aluminum is absent, and which may thus ~e termed crystalline silicates, or is replaced by a different lattice component. Such other components may be present in minor amounts, usually less than 14 mole ~, and preferably less than 4 mole %~ and include gallium, iron, boron and the like.
The silica-t:o-alumina mole ratio of an aluminosilicate zeolite may be determined by conventional analysis. This ratio is meant to represent, as closely as possible, the ratio in the zeolite crystal lattice and to exclude aluminum in the binder or in cationic or other forms within the channels~ Although zeolites with a silica to-aIumina mole ratio of at least 10 are useful, it is prefeered to use zeolites having much higher silica-to-alumina mole ratios, i.e., ratios of at least 50:1. In addition zeolites which are substantially free of aluminum, i.e., having silica-to-aIumina mole ratios of the order of 500, and up to and including infinity, are found to be useful and even preferable in some instances.
Such zeolites, after activation, acquire an intra-~rystalline sorption affinity for normal hexane which is greater than that for water, i~e., they exhibit "hydrophobic" properties.
A convenient measure of the extent to which a ~f~7f~f~
F-3182+ -17-zeolite impede~ access by molecules of varying sizes to its internal structure is the Constraint Index of the zeolite, Zeolites which provide a highly restricted access to and egress from their internal structure have a high Constraint Index, and zeolites of this kind usually have pores of small size. On the other hand, zeolites which provide relatively free access to the internal zeolite structure have a low Constraint Index. The method by which Constraint Index is determined is described fully in US-A-4,016,218, to which reference is made for details of the method.
Constraint Index CI) values for some typica:L
materials are~
_____ÇI____ ZSM-5 6-8.3 ZSM-11 6-8.7 ZSM-23 9.1 ; ZSM-35 4-5 ZSM-48 3.5 TM~ Offretite 3.7 TEA Mordenite 0.4 Clinoptilolite 3.4 Mordenite 0.5 RBY 0.4 Amorphous Silica Alumina 0.6 Dealuminzed Y (Deal Y) 0.5 Chlorinated Alumina <l Erionite 38 Zeolite Beta 0.6-l+

~'~7~2~3'~
F-3182+ ~18-Constraint Index is a critical factor in he definiton of those zeolites which are usleful in the invention. The very nature of this parame~er and the technique by which it is determined, howlever~ admit of the pos~ibility that a given zeolite can be tested under somewhat different conditions and thereby exhibit different Constraint Indices. Constraint Index seems to vary somewhat with severity of operation (conversion) and the presence or absence of binders. Likewise, other variables, such as crystal size of the zeolite, the presence of occluded contaminants, etc., may affect the Constraint Index. Therefore, it will be appreciated that it may be possible to so select tes~ conditions as to establish more than one value for the Constraint Index of a particular zeolite. This explains the range of Constraint Indices provided for some zeolites, such as ZSM-5, ZSM-ll, ZSM-34 and Zeolite BetaO
Zeolites ZSM-3, -4, -5, ~ 12, -18, -~0, -23t -34, -35, -38, -48 and beta are defined by the ~x-ray data set forth in US-A-3,415,736; 3,923,639; 3,702,886;

3,709,g79; 3,832,449; 3,950,496; 3,972,983; 4,076,342;

4,086,186; 4~01~,245; 4,046,859; 4,397,827; and 3,308,069, respectively.
Low sodium Ultrastable Y molecular sieve (USY) 2S is described~in US-A-3,293,192 and 3,449,070.
Large pore zeolites, i.e., those zeolites having a Constraint Index 1PSS than 2 and used in the first contacting hereof, are well known to the art and have a pore size sufficiently large to admit the vast majority of cornponents norrnally ound in a feed char~e stock. They are generally considered to have a pore size in excess of 7 Angstroms and are represented by, e.g., Zeolite Beta, Zeolite Y, Mordenite, ZSM-3, ZSM-4 ZSM-18 and ZSM-20 An exceptionally suitable large pore material is zeolite 2~
F-318~+ -19~

beta, although all of the~e zeolites provide hydroisomerization activity.
The preferrred hydrogenation components to be associated with the large pore zeolite are the noble metals of Group VIIIA, especially platinum, but other noble metals, such as palladium, rhenîum or rhodium, may also be used. Combinations of nob~e metalsv such as platinum-rhenium, platinum-palladium, platinum-iridium or platinum-iridium-rhenium, with combinations with non-noble lo metals, particularly of Group~ VIA and VIIIA ars of interest, particularly with metals such as cobalt, nickel, vanadium, tungsten, titanium and molybdenum, for example, platimum-tunsgten, platinum-nickel or platinum-nickel-tungsten. Base metal hydrogenation components may also be used, expecially nickel, cobalt, molybdenum, tungsten, copper or zinc. Combinations of base metals, such as cobalt-nickel, cobalt-molybdenum9 nickel-tungsten, cobalt-nickel-tungsten or cobalt-nickel-titanium, may also be used. The metal may be incorporated into the catalyst by any suitable method, such as impregnation or exchange.
The metal may be incorporated in the form of a cationic, anionic or neutral complex.
The large-pore-catalysed (isomerization) reaction is one which requires a relatively small degree of acidic functionality in the catalyst. Because of this, the zeolite may have a very high silica:alumina ratio, since this ratio is inversely relat~d to the acid site density of the catalyst. Thus, as mentioned previously, structural silica:alumina ratios o~ 50:1 or higher are preferred and~ in fact, the ratio may be much higher, e.g., 100:1, 200:1~ 500:1r 1000:1~ or even higher. Since zeolites are known to retain their acidic functionality even at very high silica:alumina ratios o the order oE
25,000:1, ra~ios of this magnitude or even higher are F-3182+ -20 contemplated.
The original cations associated with the zeolites utilized herein may be replacecl by a wide variety of other cations, accordin~ to techniques well known in the art. Replacing cations include hydrogen and metal cations, including mixtures of the same. Of the replacing metallic cations, particular refer~nce is made to cations of metals such as rare earth ~etals, manganese, as well as metals of Group II A and B of the Periodic Table, e.g., zinc, and Group VIII of the Periodic Table, e.g. nickel, platinum and palladium.
The intermediate or medium pore size zeolites used in the second contacting hereof have a Constraint Index between 2 and 12 and an effective pore size of generally not greater than about 7 Angstroms, and freely sorb normal hexane. In addition, the structure provides constrained access to larger molecules. It is sometimes possible to judge from a known crystal structure whether such constrained access exists. For example, i the only pore windows in a crystal are formed by 8-membered rings of silicon and aluminum atoms, then access by molecules of larger cross-section than normal hexane is excluded and the zeolite is not of the desired type. Windows of 10-membered rings are preferred, although in some instances excessive puckering of the rings or pore blockage may render these zeolites ineffective. The preferred medium pore zeolites in this invention include those having the structure of ZSM-5, ZSM-ll, ZSM-12, ZSM-23, 2SM-35, ZSM-38, ZSM-48 and TMA Offretite.
The medium pore zeolite is associated with a hydrogenation/dehydrogenation componentt just as disclosed in relation to the large pore zeolites~ It is not essential, but may be beneficial, to use different hydrogenation/dehydrogenation components for the medi~m ~7~
F-3182+ -21-pore and large pore zeolites.
The acidity of the medium pore zeolite will usually be very similar to the acidity of the large pore zeolite~ If it is desired, for reasons vf economy or otherwise, to use a noble metal promoter in association with a large pore zeolite, and a base mel:al promoter in association with a medium pore zeolite, it may be beneficial to operate with different acidities, or silica~alumina ratios, in the large pore and medium pore zeolites~ Best results will be obtained when the ~cidity of the medium pore zeolite is matched to the strength and amount of the hydrogenation/dehydrogenation component incorporated in the medium pore æeolite.
It will usually be beneficial to incorporate the medium pore zeolite into a conventional matrix, as discussed previously ~ith regard to the use of matrix encapsulating agents for the large pore zeolites. It is possible, and preferable, to operate with the same matrix material for both the medium pore zeolite and the large pore zeolite.
In general, hydrodewaxing conditions include a temperature of between about 450F (230C) and about 750F
(400C~, and a pressure between 0 (1 bar) and 1000 psig (70 bar), preferably below 600 psig (42.5 bar). The liquid hourly space velocity (LHSV), i.e~., volume of feedstock per volume of catal~st per hour, is generally in the range of 0.1 to 5.0, and preferably in the range of 0O2 to 2.0~ Both stages of the ca~ca~e process are operated in the presence of hydrogen at a hydrogen-to-feedstock ratio of generally between about 400 and about 8000 (71 to 1424 m3/m3) and preferably between about 800 and 4000 standard cubic feet ~SC~) (142.5 to 71~ m3/m3~ of hydrogen per barrel of feed.
In cascade operation at least 90~, and ~7~
F-3182+ -22-preferably all, of the material passed over the large pore zeolite is also passed over the medium pore zeolite7 In some embodiments there is no intermediate separation or cooling of fluid passing from one reaction zone to the next, In its simplest form, a cascade operation may be realised by using a large down flow reactor wherein the lower portion contains the catalyst comprisi~g the medium pore zeolite and the upper portion contains the catalyst lo comprising the large pore zeolite.
Two or more reactors in series may also be used, e.g., a three-reactor system, the first one or two reactors in series containing the relatively larcJe pore zeolite, the last, and optionally all or a portion of the second reactor, containing the medium pore zeolite.
According to one embodiment, however, it is critical in a two-stage cascade process to operate the first stage under mild conditions, such that the pour point of the charge stock is only reduced to no less than ~50F (~10C), preferably no less than +70F (+21C). Another criticality in this process is that the pressure must be no greater than 1000 psig, preferably below 600 psig~
Although both reactors are confined to the same temperature range of 450 to 750F (230-400C), and preferably 500 to 700F (276-371C), they can be operated under the same or different temperat~res as desired.
It is frequently advantageous to conduct hydrotreating either immedidately before or after catalytic dewaxing. Hydrotreating will usually be practised when necessary to remove sulfur or nitrogen or to meet some oth~r product specification~ Hydrotreating the feed before subjecting it to catalytic dewaxing advantageously converts many of the catalyst poisons in the hydrotreater or deposits them on the hydrotreating ~7~

catalyst. Any conventional hydrotreating catalyst and processing conditions ~ay be used.

Example 1 The charge stock was a severely hydrotreated waxy heavy neutral base stock having the following properties:

Specific Gravity 0.861 API 32.8 Pour Point, F (C) +130 (+54) Viscosity KV at 100C, cs 10.39 Nitrogen, ppm 19 CCR ~0.1 A fixed-bed, down-flow operation was employed for both the cascade two-stage scheme and the single-stage processing. In the cascade two--stage operationl lOcc of 0.6% Pt/Zeolite Beta/A12O3 extrudate catalyst was mixed with an equal volume of sand and placed in the first reactor. The platinum catalyst was steamed at 1000F
(538C) for 72 hours prior to platinum exchange~ lOcc of a steamed 1.1~ Ni/ZS~-5 extrudate catalyst was mixed with an equal volume of sand and placed in the second reactor. Both catalysts were presulfided prior to catalystic lube processing after the cascade operation. For single-stage processing, the first catalyst was by-passed and the feedstock was directly charged into the second reactor. The results and process condltions are given in Table 1.

g' Table 1 Oper ting ModeCascade Two-Stage Single Stage Pressure, psig (bar)400 (28.6) 400 (28.6) H2 Circulation, SCF/B (m /m )4000 (712) 4000 (712) Temp., F ( C) 1st Reactor (Pt/Zeolite Beta)575 (302) ----2nd Reactor (Ni/ZSM-5) 530 (277) 605 (472) LHSV
1st Reactor 1.1 ----2nd Reactor 1.1 1.1 Product Yield, wt.%
Cl+C2 G.l 0.5 c3+c4 5.6 l5.6 C5 - 330F Naptha 15.7 19.3 330-650F Distillate10.8 2.6 650Ff Lube 67.8 62.0 Properties of Lube Pour Point (lst Reactor) ~75F (24C) ----Pour Point (2nd Reactor) +20F (-6.7C) +20F
- VI (2nd Reactor) 97 88 Catalyst Aging Rate, F/Day 1st Reactor ~* ----2nd Reactor * 2.7 (1.5C) * No aging was observed during 21 days on stream under constant conditions.

(330F=166C; 650F=343C) z~

Example 2 For this example, a severely hydrotreated waxy bright stock was used having the following properties:

Specific Gravity 0.887 API 28.8 Pour Point, F (C) +160 ~+71) Viscosity KV at 100C, cs 26.99 Nitrogen, ppm 2 CCR, ~ 0 4 The same experimental procedures as in Example 1 were employed except that a Ni/ZSM-5 catalyst was used for the single-stage processing. The results and the processing conditions are presented in Table 2:

..~..

Table 2 Operating Mode Cascade Two-Stage Single Stage Pressure, psig (bar) 400 (28.6) 400 (28.6) H2 Circulation SCF/~ (m3/m3) 4000 (712)4000 (712) Temp., F ( C) 1st Reactor (Pt/Zeollte Beta) 575 (302) 2nd Reactor (Ni/ZSM-5) 548 (287)616 (324) LHSV
1st Reactor 1.1 ----2nd Reactor l.l 1.0 Product Yield, wt.~ ~
C4- 9.5 19.0 C5 - 330F Naptha ~ 17.6 18.0 330 650F Distillate 8.6 4.0 650F Lube _ -64.3 59.0 Properties of Lube- ~ ~
Pour Point (lst Reactor) +75F (24C) ----Pour Point (2nd Reactor) +10F (-12.2C) ~10F
Catalyst Aging Rate, F/Day 1st Reactor 0.3 (0.17C) ----2nd Reactor 0.5 (0.28C)9.7*(5.4C) * 1.4F/Day (0/78C) after the transition temperature of 616F (324.5C).

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Example 3 Example 3 was designed to show the effective differences of pressure on the lube yield obtained fro~ the first stage (hydroisomerization) reactor using hydrotreated waxy bright stock as a charge stock. The same catalyst and experimental procedures as in Example 1 for the first reactor were employed. The results and the processing conditions are given in Table 3:

Table 3 Effect of Pressure on Lube Yield From First Stage Hydroisomerization Pressure, psig (bar) 400 (28.6) 2800 (194) 400 (28.6) 2800 (194) Pour Point of Lube F (C) +75(24) +75 +30(-1.1) +30 Temp., F (C) 575(302) 573(300)602(316) 616(324) Product Yield, wt %
C4 0.9 0.0 5.1 0.9 C5-330F Naptha 3.4 3.9 23.7 32.1 330-650F Distillate 7.2 9.9 20O9 21.9 650F Lube 88.5 86.2 50.3 44.9 From Table 1, it is noted that in the cascade two-stage operation, the lube fraction in the first reactor effluent had a pour point of +75F and was further reduced to +20F
(-6.6C~ as a result of the second stage dewaxing. The cascade two~stage operation gave an increased lube yield (67.8%
vs. 62.0% at the same +20F pour point), a higher VI (97 vs.
88) and improved ZSM-5 catalyst stability.
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F-3182+ -28-ReEerring now to Table 2, the pour point of the lube fraction was reduced from ~75 to -~10P as a result of the second stage dewaxing process. Again, the cascade operation exhibited enhanced lube yield at the same pour point for the waxy bright stock.
Table 3 shows the effect of pressure on the lube yield obtained from the first stage (hydroisomerization~
process using the hydrotreated waxy bright stock as a charge stock. At a given pour point of lube product, it 10 can be seen that the lower pressure gave a higher lube yield. Table 3 also shows that the lube yield from the first stage reactor at 400 psig was decreased from 88.5 wt. ~ to 50.3 wt. ~ when the pour point of the lube ~raction was reduced from +75 to ~30F. This indicates 15 that severe conditions in the first stage reactor would significantly reduce the overall yield in the cascade two-stage operation. It should be noted that the 50~3 wt %
lube yield is already below the S9 wt. % lube yield which can be achieved from single-stage shape selective dewaxing 20 alone, as illustrated in Table 20 Therefore, it is not desirable in this context to operate the first stage in such a way that the pour point of the lube fraction is reduced to below approximately +50F, and preferably ~70F.
Thus, it can be seen that the use of a large pore zeolite catalyst and a medium pore zeolite catalyst in a cascade catalytic lube process results in a better lube yield, a more valuable by-product in terms of distillate yield, a higher viscosity index, and improved 30 catalyst stability for the second stage process than with a standard lube dewaxing process in which lube base stocks are dewaxed only over medium pore zeolite catalysts.

F-3182+ -29-~ x3m~

This Example employs a solvent~refined raffinate oil chargestock having the following properties:

Specific Gravity 0.877 API : 29.8 Pour Point, F (C) 120 ~50) Cloud Point, F ~C) >120 (>50l Viscosity KV at 100C 11.45 Sulfur~ wt. % 0.~8 Basic Nitrogen, ppm 61 Nitrogen, ppm 61 : Hydrogen, wt. % 13.79 CCR~ wto % ~ 0~08 :::: - ~ Bromine Number 1 0 ~ ;15 ~ ASTM Color ; 4 5 :: :
: It lS a comparative~example, illustrating the effect of steamed 1% Ni-ZSM-5 ~(alpha = 70) catalyst on the~
. : chargestock as it was passed over the catalyst in a single 20~ reactor application. The catalyst was loaded into a f~ixed-bed reactor. The catalyst was reduced ~_s~t~ at : 900F t48~2oc) and 400~psig (2~8.6 bar) H2~. Thereafter, the reactor~:temperature was lower~e~d to the de~sired setting~and ; the chargestock was passed over the catalyst along:with hydrogen under the controlled process conditions which are recited in Table 4.~
-~;27~
F r3182~ ~3 0--~3bl e_ ~

Temperature, F (C) 614 ~323) Gas H2 Circulalcion, SCF/bbl . 34Q (60.$ m3/m3) LHSV, vJv/hr . 99 Yields, wt0 ~6 ~1 + C3 3 .

C~; I 3 . 2 C6 ~ 330~F 3.5 330-650F 1. 7 6 50F~ Lube 8 3 API Gravity 25 . 5 Pour Point, F (C) 25 ~-3.9) Cloud Pointy F (C~ 28 ~-2.23 Flash Point (COC3, F (C) 558~ ~292 KV at 4û~C 145 . O
KV at 100C 13 . 66 SUS at 100 F (38C) (calc) 764 Viscosity Index 88 Bromine Number 0 . 8 Sulfur, wt. % 1.22 ( 3 3:0- 6 5 0 F = 16 6 - 3 4 3 C ) ~ ~ ' ~ .

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F-3182+ -31-~3mElgs-s=~

Examples 5-23 illustrate a dua.l catalyst cascade operation employing steamed 0~6% Pt/Zeolite Beta in the first zone and steamed 1.0% Ni/ZSM-5 in the second zone of a two-zone reactor~ A fixed-bed, ~own-f:Low operation was employed for the cascade two-zon~s~h ~ e, Both catalysts were reduced i~_~it~ of 400 psig~o~ hydrogen and 900F
(480C) for 1 hour. The results and process conditions are given in Table 5.

-32~ 7~
Table 5 Example No. 5 6 7 8 9 _ _ Temperature, F (C) First Reactor650 (343) 650 650 650 650 Second Reactor630 (332) 550 (288) 684 (362) 689 (365) 608 (320) Time on Stream, Days 2.5 4.5 5.6 6.5 7.5 Run Time, Hrs 64.5 20.S 20.5 19.5 19.5 LHSV 1.14 0.830.92 1.01 0.93 650F Lube Yield, Wt% 90.6 87.4 90.1 88.9 85.5 Specific Gravity 0.8911 0.8887 0.8891 0.8901 0.8924 API 27.3 27.7 27.7 27.5 27.1 Pour Point, F (C) 90 (32) 85 (29.5) 70 (21) 55 (13) 35 (1.66) Cloud Point, F (C) 104 (40) 120 (49) 120 (49) 62 (16.5) 50 ~lO) KV at 100F, cs (38C) 128.6 120.9 121.7 129.6 138.5 KV at 210F, cs (99C) 11.90 12.02 12.29 12.67 12.97 15 KV at 40C, cs 113.5 107.2 108.0 114.8 122.4 KV at 100C, cs11.56 11.6811.95 12.31 12.60 SUS at 100F (38C) 598 560 564 600 642 SUS at 210F (99C) 66.1 66.5 87.5 68.9 70.1 Viscosity Index87.1 96.2 99.3 97.3 93.9 20 Sulfur, Wt % 0 93 0.640.75 0.69 0.73 Basic Nitrogen, ppm 55 56 62 61 60 Nitrogen, ppm 73 72 75 62 70 ~Hydrogen, Wt %13.73 13.7013.69 13.71 13.65 CCR, Wt % 0.06 0.040.06 0.08 0.09 ` 25 Bro~ine Number 2.6 0.8 0.5 1.3 2.2 ASIM Color L3.5 L3.5 L3.0 L2.5 L2.5 :
L = Lighter than .

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Table 5 (Cont.) Exampie No. 10 11 12 13 14 Temperature, F (C) First Reactor650 (343) 650 650 650 650 Second Reactor628 (331) 639 (337) 642 (33g) 649(343) 648 (342) Time on Stream, Days 9.5 11.5 12.5 13.6 14.5 Run Time, Hrs 85 21 21 20.5 20 LHSV 0.91 0.87 1.02 1.00 1.06 650F Lube Yield, Wt % 82.2 82.0 81.5 81.7 82.5 Specfic Gravity0.8938 0.8938 0.8936 0.8939 0.8933 API 26.8 26.8 26.9 26.8 26.9 Pour Point, F (C) 20 (-6.6) 15 (-9.5) 20 t-6.6) 20 (-6.6) 25 (-3.9) Cloud Point, F (C) 26 (-3.3) 22 (-5.6) 30 (-1.1) 26 (-3.3) 42 (5.6) KV at 100F, cs (38C) 143.4 144.2 144.2 144.6 142.40 KV at 210F, cs (99C) 13.09 13.09 13.10 13.09 13.07 KV at 40C, cs 126.5 127.7 127.2 127.5 125.7 KV at 100C, cs12.71 12.71 12.72 12.71 12.69 SUS at 100F (38C) 664 668 668 670 660 SUS at 210F (99C) 70.5 70.5 70.5 70-5 70-4 Viscosity Index91.5 90.8 91.0 90.6 92.0 Sulfur, Wt % 0.75 0.72 0.75 0.75 0.84 Basic Nitrogen, ppm 64 70 60 65 61 Nitrogen, ppm 72 70 69 81 75 Hydrogen, Wt %13.65 13.59 13.53 13.60 13.58 CCR, Wt % 0.07 0.08 0.09 0.08 0.04 Bromine Number 2.6 2.0 2.3 2.4 2.1 ASIM Color L2.0 L2.0 L2.0 L2.0 L2.5 L = Lighter Than .~:

~ 7~

Table 5 (Cont.) Example No. 15 16 17 _ _ 18 19 Temperature, F (C) First Reactor 650 (343) 650 650 650 650 Second Reactor 648 (342) 648 (342) 648 (342) 650 (343) 649 (343) Time on Stream, Days 15.5 16.5 17.5 19.5 21.5 Run Time, Hrs 19.5 l9 19 65 l9 LHSV 0.96 0.96 0.98 0.96 0.93 650F Lube Yield, Wt % 80.8 81.1 82.4 82.3 82.9 Specific Gravity 0.8933 0.8935 0.8934 0.8933 0.8939 API 26.9 26.9 26.9 26.9 26.8 Pour Point, F (C) 20 (-6.6) 15 (-9.5) 20 (-6.6) 15 (-9.5) 25 (-3.9) Cloud Point, F (C) 30 (~1.1) 28 (-2.2) 36 (2.2) 40 (4.5) 40 (4.5) KV at 100F, cs (38C) 143.1 143.8 143.2 143.1 142.5 KV at 210F, cs (99C) 13.05 13.08 13.17 13.09 13.07 KV at 40C, cs 126.3 126.9 126.4 126.3 125.8 KV at 100C, cs 12.67 12.70 12.79 12.71 12.69 SUS at 100F (38C) 663 666 663 663 660 SUS at 210F (99C) 70.3 70.5 70.8 70.5 70.4 Viscosity Index 91.1 91.0 92.7 91.7 91.9 Sulfur, Wt % 0.76 0.78 0.78 0.78 0.78 Basic Nitrogen, ppm 67 68 67 S8 66 Nitrogen, pp~ 71 64 63 75 74 ~ydrogenj Wt % 13.50 13.48 i3.49 13.47 13.43 CCR, Wt % 0.08 0.06 0.08 0.07 0.08 Bromine Number ~ 1.8 2.4 2.0 1.0 0.8 ASIM Color 2.0 2.0 2.0 L2.5 2.0 L = Lighter Than :

~7, ~ ~t7 ~

Table 5 (Cont.) _ Example No. _ 20 21 __ 22 23 Temperature~ F (C) First Reactor 650 (343) 650 650 650 Second Reactor 648 (343) 649 ~343) 649.2 (343) 649 (343) Time on Stream, Days 22.5 23.5 24.5 26.5 Run Time, Hrs 23 22 30 65 LHSV 0.95 0.90 0.93 0.95 650F Lube Yield, Wt % 83.9 83.7 83.8 84.4 Specific Gravity 0.8935 0.8935 0.8933 0.8929 API 26.9 26.9 26.9 27.0 Pour Point, F 25 ~-3.9) 30 (-1.1) 25 (-3.9) 30 (-1.1) Cloud Point, F (C) 46 (7.8) 44 (6.7) 46 (8) 52 (11.1) KV at 100F, cs (38C) 140.4 141.4 140.0 137.7 KV at 210F, cs (99C) 13.02 13.05 13.00 12.95 KV at 40C, cs 124.0 124.6 123.7 121.7 KV at 100C, cs 12.65 12.68 12.63 12.58 SUS at 100F (38C) 650 654 649 638 SUS at 210F (99C) 70.3 70.4 70.2 70 Viscosity Index 93.0 92.9 93.0 94.3 Sulfur, Wt % 0.79 0.76 0.77 0.80 Basic Nitrogen, ppm 66 66 66 64 Nitrogen, ppm 76 77 74 67 Hydrogen, Wt % 13.64 13.53 13.76 13.58 CCR, Wt % 0.09 0.08 0.06 0.08 Bromine Number 1.0 0.1 1.5 2.1 ASIM Color L2.5 L2.0 L2.0 2.0 L = Lighter than ~J
~' ~27~

F-3182~ -36 Compared to the Ni-ZSM-5 catalyst in the single stage reactor, the cascade reactor system of Examples 5-23 improved viscosity index by up to 4 num~ers. As illustrated in Fig. 1, which shows the effect of pour point on viscosity index for both a cascade and a single zone reactor, the viscosity index of solvent~refined raffinate is higher in the cascade reactor system than in the single zone reactor system at the designated pour point.
Fig. 2 illustrates the effect of the number of days a catalyst is on-stream for both a single zone and cascade reactor with regard to the temperature of the catalyst. It can be seen that after approximately 20 days on-stream, the temperature of the single zone reactor must operate in excess of 675F (357C) for efficient reaction to occur. In contrast, the cascade reactor system may operate in excess of 27 days below a reactor temperature of 675F (357C). Thus, the cascade reactor system operates more efficiently, for a larger period of time and produces a superior product for a solvent-refined raffinate chargestock, when compared to the single zone reactor.

ExamE~es~
These examples illustrate the effect of interstage separation employing a 0.6% Pt/Zeolite Beta catalyst in the first reactor and steamed 1% Ni-ZSM-5 zeolite in the second reactor. A fixed-bed, down-flow operation was employed for the cascade 2-zone scheme. The chargestock was first processed over the 0.~ Pt/Zeolite Beta under the following conditions:

-37- ~

Temperature F (C) 633-640 (334-333) LHSV
SCF H2/bbl 2500 H2, psig 400 (28.6 bar) The 650F+ portion was then fractioned out by conventional means and processed over steamed 1 % Ni/ZSM-5. The results and process conditions of the second stage are given below in Table 6.
Table 6 Example No. 24 25 26 27 Average Temperature, F (C) 551 (289) 556 (291) 560 (293) 567 (297) Time on Stream, Days 2.5 3.5 5.4 7.3 650F Lube Yield, Wt % 84.6 84~5 84.5 86.3 API Gravity 26.9 26.8 27.1 26.9 Specific Gravity 0.8940.894 0.893 0.894 Pour Point,F (C) 25 (-3.9) 25 (.3.9)30 (-1.1) 35 (1.7) Cloud Point, F (C) 46 42 48 46 KV at 40C, cs 124.3 125.l 119.7 123.8 KV at 100C, cs 12.6912.72 12.46 12.67 Viscosity Index 93.3 93.0 94.5 93.5 Table 6 (Cont.) ., Example No. 28 29 30 31 Average Temperature, F (C)571 (299)576 (302) 581 (305) 587 (308) Time on Stream, Days 8.3 9.3 10.3 12.3 650F Lube Yield, Wt % 85.5 85.6 84.9 84.7 API Gravity 26.8 26.7 26.6 26.5 Pour Point, F (C) 30 (-1.1) 30 (-1.1)20 (-6.6) 15 (~9.5) Cloud Point, F (C) 40 (4.5) 40 (4.5)28 (-2.2) 24 (-4.5) KV at 40C, cs 125.2 126.3 127.8 130.6 KV at 100C, cs 12.7012.75 12.77 12.87 Viscosity Index 92.6 92.3 91.1 90.0 ~;

~r7~4 Table 6 (Cont.) Example No. 32 33 34 35 Average Temperature, ~F (C) 587 (308) 590 (310) 593 (311) 593 (311) Time on Stream, Days 14~4 15~5 16~5 17~4 650F Lube Yield, Wt % 86~0 85~7 85~8 85~9 API Gravity 26 ~ 6 26 ~ 6 26 ~ 6 26 ~ 6 Specific Gravity 0~895 0~895 0~895 0~895 Pour Point, F (C) 15 (~9~5) 15 ( 9~5) 15 (~9~5) 15 (~9~5) Cloud Point, F (C) 28 (~2~2) 26 (~3~3) 22 (-5~6) 24 (~4~4) KV at 40C~ cs 129~0 129~3 129~2 129~5 KV at 100C, cs 12~81 12~80 12~80 12~81 Viscosity Index 90~6 90~1 90~2 90~1 Table 6 (Cont.) . _ . _ Example No. 36 37 .
Average Temperature, F (C) 592 (3113 591 (310) Time on Stream, Days 19~5 21~5 650F Lube Yield, Wt % 86.1 87~0 API Gravity 26 ~ 7 26 ~ 8 Specific Gravity 0~895 0~894 Pour Point, F (C) 20 (-6~6) 30 (-1~1) Cloud Point, F (C) 22 (-5~6) 40 (4~5) KV at 40C~ cs 127 ~ 9 126 ~ 6 KV at 100C, cs 12~75 12~70 Z5 Visco9ity Index 90 7 92 0 .__ .....

~2~

F-3182+ 3g Figure 3 .illustrates the effect of the presence of interstage separation on the second stage reactor temperature with re~ard to days onstream. It can be seen that in the first few days onstream, the dewaxin~ catalyst aged at approximately 5F (2.8C) per day with an SOC
temperature of 542F (283C). After 20 days onstream, the dewaxing catalyst lined out at ab~u 585F (307C). In contrast, the cascade dewaxing process wi~hout interstage separation had an SOC temperature of 575F (302C) and lined out at 650F. The aging rate ater line-out was 0.5F (0.28C) per day. With the conventional dewaxing process, the SOC temperature was 550F (288C) and aged at a rate of approximately 5~/day until the end of cycle temperature tset at 675F (357C)). The results indicate that the pretreatment of the chargestock over a large pore zeolite, preferably Zeolite Beta, and the removal of light ends, e.g~, the 650F- stock, can significantly reduce the severity level for the second reactor.

~ ~n the following Examples the cbargestock was a light neutral lubricating oil chargestock having the following properties:

Specific Gravity .8774 API 29.8 Pour Point, F (C) 85 (35) Viscosity KV at 100C) 5.341 Sulfur, wt. ~ 0.76 AsTrl Color *Ll.0 *L = Lighter than Examples 38 to 42 are comparative examples, showing the effects of three different catalysts on the ~;~7~Z~

F-3182+ -40-chargestock as it was passed over the catalyst in a single reactor operationO

E~am~le~
Steamed 1% Ni-ZSM-5 was loadecl into a fixed-bed reactor. The catalyst was reduced i~ t~ at 900F
(482C) and 400 psig H2 for 1 hour. Thereafter, the reactor temperature was lowered to the desired setting, the chargestock being passed over the catalyst together with hydrogen under the process conditions set forth in Table 7. The product stream leaving tha reactor was passed through a heated trap, a cold-water trap, and a gas-sampling bomb. The gas samples were analyied by mass spectrometry for Cl-C6 components. Liquid products were topped, under less than 0.1 mm Hg pressure and miximum pot temperature of 400F (204.~5C), to isolate the 650F+
fraction. Some of the topped samples were processed through a simulated distillator~ The light liquid products, i.e., the condensate from the cold trap and the overhead from the topped samples, were analyzèd by gas chromatography. Overall material balances were made based on total liquid ~eed charge pl~s hydrogen. The results are~set forth in Table 7.

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Table 7 Temperature, F (C) 580 (304) Pressure, psig 400 (28.6 bar) Gas H2 Circulation, SCF/bbl 2500 (445 m3/m3) LHSVr v/v/hr 1. 00 Yields, wt. %
Cl +C2 0 . 1 C3 1.5 C4 4.0 C5 4.3 C6 650F 10.8 650 F+ Lube 79.5 (610F)(321C) API Gravity 28.6 Specific Gravity 0.884 Pour Point, F/C 15/-9.5 KV at 40C 42.99 KV at 100C 6.325 ~ Viscosity Index 92.8 ;~ 20 Example 39 This example illustrates the effect of a 0.5 %
Pt-ZSM-5 catalyst on the chargestock. The platinum catalyst was reduced in situ at 900F (482C) and 400 psig of hydrogen for one hour before introducing the feed into the reactor. The procedure of Example 38 was followed under conditlons specifled in Table 8, which also recites the results.

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-~2-Table 8 Temperature, F (C) 565 (296) Pressure, psig 400 (28.6 bar) Gas H2 Circulation, SCF/bbl 2500 (445 m3/m3) LHSV, v/v/hr 1.28 Yields, wt. ~
Cl +C2 0.2 C3 4.4 C4 5.4 C5 1.5 C6 - 650F 8.8 650F~ Lube 80.6 (610 ~)(321 &~
API Gravity 28.3 Specific Gravity 0.885 Pour Point, F/C 5/-15 KV at 40C 45.35 KV at 100C 6.505 Viscosity Index 91.5 .

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Example 40 This example illustrates the effect of a .44 %
pt-Zeolite Beta on the chargestock. The procedure of Example 39 was followed under conditions specified in Table 9, which also recites the results:
:, .
. Table 9 , -- ~
~emperature, F (C) 800 (427) - Pressur~e, psig 400 (28.6 bar) Gas H2 Circula~ion, SCF/bbl 2500 (445 m3/m3) Time on Stream, Days 6 LHSV, v/v/hr 1.0 Yields, wt. %
Cl +C2 1 . O
C3 2.1 C4 6.1 C5 3.3 C6 - 650F (343C) : 35.0 ~: 650F+ Lube 52.5 : API Gravity ~ 29.0 : Specifi~ Gravity 0.881 Pour Po-mt, FjC . 5/-15 KV at 4:0~C 13.05 ~ KV at;100C 3.035 :~ Viscosit~Index ~ 80.5 ^
- ,.
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Example _ This example illustrates the effect of .44 ~
Pt-Zeolite beta on the chargestock under reaction conditions different from those of Example 40 (reaction temperature 550F vs. 800F). The procedure of Example 39 was followed under conditions specified in Table lO, which also recites the results:

Table lO

Temperature, F (C) 550 (288) Pressure, psig 400 (28.6 bar) Gas H2 Circulation, SCF/bbl 2500 (445 m3/m3) 15 Time on Stream, Days 0.5 LHSV, v/v/hr l.0 Yields, wt. %
Cl +C2 Q.2 C3 0.1 c4 0.1 C5 0.1 C6 ~ 650F (343C) 3.6 650F+ Lube 95.9 API Gravity 29.0 25 Specific Gravity 0.881 Pour Point, F/C 95 (3 ) KV at 40C 27.98 KV at 100C 5.143 :

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Example 42 -This example illustrates the effect of .5 ~ Pt/ZSM-ll on the chargestock. The procedure of example 39 was followed under conditions specified in Table 11, which also recites the results.

Table 11 Temperature, F (Cl 540 (282) : Pressure, psig 400 (28.6 bar) Gas H2 Circulation, SCF/bbl 2500 (445 m3/m3) Time on Stream, Days 4 LHSV, v/v/hr 1.0 Yields, wt. ~
Cl +C2 0.3 C 2.3 C4 2.8 C5 2.4:
: C~ -~650F (343C) 10.3 ~ 650 F+ Lube 81.9 API Gravity 29.0 : Specific Gravity 0.881 Pour Point, F/C 15/-8.6 K~t at 40C 42.32 :; 25 KV at 1;00C 6.311 Viscosity Index 95.2 , ~

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~7l ,~.~ i, ~ ~4~4 F~3182+ -46-~3-m~le_~
This Example illustrates the effect of 0~5%
Pt/ZSM-ll/Zeolite Beta in admixture on the chargestock.
ZSM-ll was first calcined in a nitrogen atmosphere at 1000F (538C~ for 3 hours to decompose tetrabutyl ammonium and other organics in its structure. The ZSM~ll was subsequently N~4NO3 exchanged to reduce its Na content to less than 0.02~. Zeolite Beta was pretrea~ed similarly~ 32.5 parts of N~4ZSM-11, 32.5 parts of NH4-~eolite Beta and 35 parts of alpha alumina monohydrate were mulled together to form a uniform mixture which was then impregnated with H~PtC16 in a stream of CO2. The sample was finally si2ed to 30/60 me~h and activated with an air calcination fsr 3 hours at 1000F ~538C). The sample was analyzed and found to contain 0.49 wt. % and 0.01 wt. ~ Na, The runs were made in a 15/32" (1.19 cm) ID
fixed-bed reactor with a spiral preheater and a three-zone furnace for good temperature control. The platinum ; composite catalyst was reduced ~n_sit~ at 900F (482C) ~and 400 psig of hydrogen or one hour before the reactor temeprature was lowered to 500F ~260C) and the feed was started pumping into the reactor. The product stream leaving the reactor was passed through a heated trap, a ~ cold water trap, and a gas-sampling bomb. The gas samples were analyzed by inass spectrometry for Cl-C6 components, Liquid~products were topped under less than 0.1 mm-Hg ;; ~ pressure, maximum pot temperature 40~F (204C), to isolate the 650F+ part. Light liquid products ~the cvndensate in the cold trap and the overhead from topping) were sent for gas chromatography anal~-sis. Overall material balances were made based on total liquid feed charge plus hydrogen.
The run conditions and results are specified in ~7~

Table 12 Temperature, F (C) 580 (304) Pressure, psig . 400 (28.6 bar) Gas H
Circulation, SCF/bbl 2500 (445 m3/m3) Time on Stream, Days 6 LHSV, v/v/hr l.0 Yields, wt. %
Cl +C2 0 . 1 c3 2.6 C4 2.9 C5 2.8 C6 - 6500F (343C) 7.3 650F+ Lube 84.3 API Gravity 29.1 Specific Gravity 0.881 Pour Point, F/C 20/-6.7 ~V at 40C 41.06 KV at 100C 6.236 Viscosity Index 97.5 ''~;~' ~'~7~

Examples 44 and 45 These examples illustrate a dual catalyst cascade operation employing 0.44 % Pt/Zeolite 3eta in the first zone and 0.5 % Pt/ZSM-ll in the second zone o~ a two-zone reactor.
A fixed~bed, down-flow operation was employed for the cascade two-zone scheme. Both catalysts were reduced in situ under 400 psig of hydrogen at 900F (480C) for 1 hour. The results and process conditions are given in Table 13.

Table 13 Example No. 44 45 Temperature, F (C) First Reactor554 (290) 555 (290) Second Reactor546 (286) 545 (285) Pressure, psig400 (28.6 bar)400 (28.6 bar) H2 Circulation, SCFjbbl2500 (445 m 3!m3) 2500 (445 m3/m3) Time on Stream, Days2 3 LHSV, v/v/hr tOverall) .5 .5 LHSV (First Reactor)1.0 1.0 LHSV (Second Reactor) 1.0 1.0 Yields, wt. ~
Cl +C~ .3 .1 C3 1.4 1.8 C4 3.1 3.3 c5 2.6 2.6 C~ - 650F (343C) 9.4 7.2 650F+ Lube 83.2 85.0 ~PI Gravity 28.8 29.0 Specific Gravity 0.883 0.882 Pour Point, F/C 15/-8.6 20/-6.7 KV at 40C 42.63 41.46 KV at 100C 6.322 6.250 Viscosity Index 93.4 96.3 ,~,. ~.

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F 3182+ -49_ Compared to the Ni-ZSM~5 (Example 38) and Pt ZSM-5 ~Example 39) in the single reactor operation, Pt/ZSM-ll (Example 42) improved product yields by approximately 5% and 4%r respectively, and VI by about 2 and 4 numbers, respectively.
Compared to Ni-ZSM-5 in the single reactor operation, the cascade operation IExamples 44 and 45) enhanced catalyst activity by 25-35F (13.9-19.5C) and improved product yields by 5% and VI by 3 numbers, lo respectively. Compared to Pt/Zeolite Beta, the cascade operation enhanced catalyst activity by at least lS0F
t83.5C), lube yield by 32% and VI by 16 numbers. As illustrated in Example 41, Pt-Zeolite Beta exhibits very little dewaxing activity at a temperature of 550F;
however, the dewaxing activity is grea~ly enhanced by the use of Zeolite Beta and ZSM-ll in a cascade relationship.
The cascade operation had a slightly lower catalyst activity, i.e., 5-15F ~2.8-8.5C), than Pt/ZSM-11 in the single reactor operationg but the cascade operation produced 3% more luhe yield. Equivalent lube yield and product VI were observed between the cascade operation and the single reactor operation utilizing the composite Pt~ZSM 5/Zeolite Beta catalyst. Further, the cascade operation ofered a catalyst activity advantage of 25-35F. Thus, it can be seen that a dual catalyst cascade operation utilizing a large pore zeolite catalyst ~ and ZSM-ll results in enhanced catalyst activity, better - lube yield and a higher viscosity index over the single reactor operation~
Although the invention has been described in conjunction with specific embodlments, it is evident that many alternatives and variations will be apparent to those skilled in the art in light of the foregoing description.
Accordingly, the invention is intended to embrace all of 2~

F-3182~ -50-the alternatives and variations that fall within the spirit and scope of the appended claims.

Claims (27)

1. A process for dewaxing a hydrocarbon feedstock which comprises, first, contacting said feedstock at elevated temperature with a catalyst comprising a crystalline zeolite having a constraint index less than 2, possessing acidic sites and associated with a catalytically effective quantity of a component possessing hydrogenation/dehydrogenation activity, and, second, contacting at least the majority of the effluent from said first contacting, at elevated temperature, with a catalyst comprising a crystalline zeolite having a constraint index greater than 2, possessing acidic sites and associated with a catalytically effective quantity of a component possessing hydrogenation/dehydrogenation activity, and recovering a normally liquid hydrocarbon product of reduced wax content relative to said feedstock.

2. A process according to claim 1 wherein the first and/or second contacting is carried out in the presence of added hydrogen.

3. A process according to claim 1 wherein each hydrogenation/dehydrogenation component comprises a metal of Group VI, VII and/or VIII of the Periodic Table.

4. A process according to claim 3 wherein said metal is a Group VIII noble metal and constitutes 0.1 to 5 wt. % of the catalyst with which it is associated.

5. A process according to claim 4 wherein the metal constitutes from 0.3 to 3 wt. % of the catalyst.

6. A process according to claim 3 wherein said metal is a non-noble metal and constitutes 0.3 to 25 wt. %
of the catalyst with which it is associated.

7. A process according to claim 1, 2 or 3, of which the overall liquid hourly space velocity is between 0.1 and 5.

8. A process according to claim 1, 2 or 3 wherein the overall liquid hourly space velocity is between 0.2 and 3Ø

9. A process according to claim 1, 2 or 3, wherein each contacting is carried out at a temperature in the range 232 to 371°C (450 to 700°F), a liquid hourly space velocity of 0.1 to 10 and a pressure no greater than 70 bar (1000 psig).

10. A process according to claim 1, 2 or 3, wherein each contacting is carried out at a pressure below 42.5 bar (600 psig).

11. A process according to claim 1, 2 or 3 wherein each contacting is carried out at a pressure below 28.5 bar (400 psig).

12. A process according to claim 1, 2 or 3 wherein each contacting is carried out at a liquid hourly space velocity of 0.2 to 6Ø

13. A process according to claim 1, 2 or 3 wherein the first and/or second contacting is carried out in a fixed, slurry or moving bed unit.

14. A process according to claim 1, 2 or 3, wherein the zeolite employed in said first contacting is zeolite Y, ultrastable zeolite Y, dealuminised zeolite Y, ZSM-3, ZSM-18 or ZSM-20.

15. A process according to claim 1, 2 or 3, wherein the zeolite employed in said second contacting is zeolite ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48 or TMA
Offretite.

16. A process according to claim 1, 2 or 3, wherein the zeolite employed in said first contacting is zeolite beta.

17. A process according to claim 1, 2 or 3, where the hydrogenation/dehydrogenation component associated with the zeolite is platinum.

18. A process according to claim 1, 2 or 3, wherein said feedstock contains waxy components which are normal and/or slightly branched paraffins.

19. A process according to claim 1, 2 or 3, wherein the normally liquid effluent from said first contacting has a pour point less than that of said feedstock but no less than 50°F (10°C).

20. A process according to claim 1, 2 or 3 wherein the normally liquid effluent from said first contacting has a pour point of no less than 70°F (21°C).

21. A process according to claim 1, 2 or 3 wherein the zeolite employed in said second contacting is zeolite ZSM-5.

22. A process according to claim 1, 2 or 3 wherein the zeolite employed in said second contacting is zeolite ZSM-5 and the hydrogenation/dehydrogenation component associated with the zeolite is nickel.

23. A process according to claim 1 wherein said feedstock is a solvent-refined raffinate.

24. A process according to claim 23 wherein the activity of the zeolite employed in said first contacting is reduced prior to the contacting.

25. A process according to claim 23 or claim 24 wherein a 650°F- (343°C-) fraction is removed from the effluent of said first contacting before said second contacting is performed.

26. A process according to claim 1, 2 or 3 wherein at least the majority of said feedstock has a boiling point greater than 250°C.

27. A process according to claim 1, 2 or 3 wherein at least the majority of said feedstock has a boiling point greater than 250°C and the zeolite employed in said second contacting is ZSM-11.