US3532619A - Hydrocatalytic treatment wherein temperatures are modified when changing feedstocks - Google Patents

Description

Oct. 6, 1970 H. REES ETAL 3,532,619

HYDROCATALYTIC TREATMENT WHEREIN TEMPERATURES ARE MODIFIED WHEN CHANGING FEEDSTOCKS Filed July 15, 1966 I I l 1 1. sum: 12m. AFTER muss. v LSAMPLE 2am. AFTER cumsea-z a. SAMPLE LBhrs. AFTER muss.

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HOWARD REES BRIAN LINWOOD WRIGHT BY Y MORGAN, FINNEGAN, DURHAM 8| PINE ATTORNEYS United States Patent 3,532,619 HYDROCATALYTIC TREATMENT WHEREIN TEMPERATURES ARE MODIFIED WHEN CHANGING FEEDSTOCKS Howard Rees and Brian Linwood Wright, Glamorgan, Wales, assignors to The British Petroleum Company Limited, London, England, a corporation of England Filed July 15, 1966, Ser. No. 565,585 Claims priority, application Great Britain, July 30, 1965, 32,646/65 Int. Cl. C10g 23/02, 43/02 US. Cl. 208-27 10 Claims ABSTRACT OF THE DISCLOSURE When changing wax or lubricating oil feedstock during hydrofinishing the new product may be off-specification for a while. This off-specification period may be reduced by raising the temperature at the changeover and then reverting to normal temperatures.

The problem occurs when changing from microcrystalline to crystalline wax or from solvent treated to nonsolvent treated lub oils. The temperature is raised to 750 F. maximum for 5-50 hours in the presence of a bufier feedstock (e.g., vacuum gas oil) or the new wax or lube oil feedstock. The pressure may be lowered simultanously with the temperature increase.

This invention relates to the mild hydrocatalytic treatment of waxes and lubricating oils to improve colour, colour stability and odour, a treatment commonly referred to as hydrofinishing.

The hydrofinishing of waxes is coming more into use on a commercial scale, replacing the older method of finishing waxes by treatment with acid and/or a solid adsorbent such a clay. To be acceptable commercially a hydrofinishing process has not only to be able to treat all grades of wax but also to allow changes in the grade of wax being treated on the run (i.e., without taking the plant off-stream).

Waxes can be conveniently divided into two classes. The crystalline waxes are usually obtained from distillate petroleum fractions and consist largely of n-parafiins: the microcrystalline waxes are usually obtained from petroleum residues and contain isoparaffins. The microcrystalline Waxes normally need a higher hydrofinishing temperaturethan the crystalline waxes to give the required improvement in colour.

The hydrofinishing of lubricating oils is now well established as an alternative to acid and/or clay treatment and it, too, has to be able to treat different grades of oil and to allow changes in the grade of oil being treated on the run. As with waxes, lubricating oils may be divided into two main grades, the nonsolvent treated grades, which are usually the lighter spindle oils and the higher boiling solvent treated grades. The nonsolvent treated grades usually required slightly lower hydrofinishing operating temperatures than the solvent treated grades. Solvent treatment means a preliminary treatment with acid or a 3,532,619 Patented Oct. 6, 1970 selective solvent to reduce the aromatic content of the lubricating oils. The nonsolvent treated grades thus have a higher aromatic content.

It has been found that changing from a crystalline to a microcrystalline wax feedstock presents no particular problems, but that when changing from a microcrystalline to a crystalline wax feedstock a considerable period elapses before the product from the new feedstock reaches an acceptable colour. The off-specification period my be for example, nearly 200 hours. Similarly when changing from a nonsolvent treated grade to a solvent treated grade of lubricating oil there are no problems; but problems arise when the reverse change is effected. When changing from a solvent treated to a nonsolvent treated lubricating oil the off-specification period may be less than for waxes, being for example about 30 hours, but any loss of successful operating time is clearly undesirable. Without being bound by any theory, it is postulated that the change in operating conditions or the change in hydrocarbon composition of the feedstock causes colourforming bodies adsorbed onto the catalyst to be desorbed into the new product, thereby throwing it off-specification.

The present invention is thus concerned with facilitating the change over of feedstocks in hydrofinishing.

In the accompanying drawing which forms par-t of the instant specification and is to be read in conjunction therewith, the figure is a graph illustrative of improvement in colour stability of hydrofinished feedstock with elapse of time after changeover.

According to the present invention, a process for the hydrocatalytic refining of waxes or lubricating oils at elevated pressure in the presence of hydrogen and a hydrogenation catalyst in which the feedstock is changed from a microcrystalline to a crystalline wax or from a solventtreated to a nonsolvent treated grade of lubricating oil is characterised in that the changeover is effected by discontinuing the passage of the existing feedstock while continuing the passage of hydrogen, substituting a petroleum hydrocarbon feedstock other than the existing feedstock raising the temperature to above that used for the first mentioned feedstock up to a maximum of 750 F. for a period of from 5 to 50 hours and then lowering the temperature and commencing processing of a crystalline wax or nonsolvent treated grade of lubricating oil.

The invention thus essentially makes use of a period of high temperature operation at the feedstock changeover during which, it is believed, the desorption of colour-forming bodies from the catalyst is accelerated. The material processed during this high temperature period will contain these colour bodies and hence it is desirable, if possible, to use as the other petroleum hydrocarbon feedstock a material of lower quality and cost than lubricating oil or wax which will not be adversely affected by the presence of colour-forming bodies or which is to be subsequently processed in another unit such as a hydrofiner. This type of other feedstock will hereinafter be referred to as a buffer feedstock and an example of a suitable buffer feedstock is gas oil, particularly a gas oil having a boiling range of 250 to 400 C. A buifer feedstock is particularly conveniently used when hydrofinishing lubricating oils. However, the other feedstock may be a nonsolvent treated grade of lubricating oil particularly if there is oil of this type available surplus to requirements. When hydrofinishing waxes it may be difficult to find a buffer feedstock which will not introduce other undesirable matter into the reaction system and throw the wax off specification for other reasons. In this case, the other feedstock is desirably crystalline Wax, particularly the crystalline wax to be subsequently processed. Clearly some off-specifications crystalline Wax will be produced with this technique but the raised temperature greatly reduces the off-specification period to one of less than 50 hours and there is still a substantial gain in operating efficiency.

The hydrofinishing process conditions for wax and lubricating oil may be chosen from the following broad ranges:

The ratio by weight of molybdenum oxide to cobalt oxide should be at least 1.5:1 and is preferably at least 3:1 and the amount of iron oxide is desirably in excess of the amount of molybdenum oxide.

The support is preferably a refractory oxide selected from Groups II to V of the Periodic Table, particularly one which has a low activity in itself under the hydrogenation conditions used. The preferred support is alumina. The alumina is preferably calcined before the addition of the molybdenum and nickel oxides at a temperature of from 500 to 900 C., particularly from 700 to 900 C.

The invention is illustrated by the following comparative examples.

Preferred range Particularly preferred range Particularly preferred temperatures are:

450-1,000 p.s.i.g. (27-67 ats.). 0.2-4 v./v./hr.

Lubricating Oil Non-solvent Mieroerystalline wax Crystalline wax Solvent treated treated 5154575 F. am-357 0. 475-575 F. (246-302" c.). .{g; gf gggg g gf During the period of operation at the raised tempera- EXAMPLE 1 ture the hydrogen flow rate and feedstock space velocity may be Wlthm the same ranges as those used for proc' 35 A hydrocatalytic process for the refining of waxes used essing. The pressure may also be within the processing range, but it is preferred, paticularly when treating waxes, to lower the pressure to below the actual processing pressure used, for example to a pressure within the range 0450 p.s.i.g. (127 ats.), particularly 0-250 p.s.i.g. (l-16 ats.).

The catalyst may consist of one or more hydrogenating metals on a support, preferably chosen from the metals of Group VIa or VIII of the Periodic Table, or rhenium. The metals, particularly the Group VIa metals, the iron group metals or rhenium may be used in the form of their oxides or sulphides. The amounts of each metal may be within the following ranges:

Group VIa metals3-25% wt., calculated as the oxide M003, Cl'203 01' W207.

Nickel or cobalt-l% wt., calculated as NiO or C00.

Iron325% wt., calculated as Fe O Platinum group metals-0.14% wt., calculated as the metal.

Rheniurn125% wt., calculated as R6 0 One particularly preferred catalyst, especially suitable for wax hydrofinishing, consists of the oxides of nickel and molybdenum on a support. The amount of molybdenum oxide may be from 3 to wt. by weight of total catalyst calculated as M00 and the amount of nickel oxide may be from 3 to 15% wt. calculated as NiO. Particularly preferred catalysts contain from 9 to 15 wt. of molybdenum oxide and from 3 to 5% wt. of nickel oxide.

Another particularly preferred catalyst, especially suitable for lubricating oil hydrofinishing consist of the oxides of iron and molybdenum, and preferably also cobalt, on a support. The amounts of the oxides may be:

Iron oxide (Fe O percent wt.-420 preferably 6-1.5

Molybdenum oxide (M00 percent wt.-420 preferably 5-12 Cobalt oxide (C00) percent wt.0l2 preferably 0.5-4

the following catalyst:

Percent wt. Nickel oxide (NiO) 4.1 Molybdenum oxide (M00) 10.0 Alumina (Al O )-Balance.

Various grades of wax were treated under the following conditions:

Total pressure800 p.s.i.g.

Hydrogen partial pressure-800 p.s.i.g.

Wax space velocity0.5 v./v./hr.

Hydrogen flow rate36 v./ volume of wax (200 s.c.f.b.).

A microcrystalline wax having a congealing point of 160 F. and penetration at 25 C. of 25 mm./ 10 as measured by ASTM Test Method D1321/ 57 was first passed over the catalyst at a temperature of 650 F. for a period of 55 hours. The feedstock had a colour of 5.5 and the product a colour of Ll.0 as measured by ASTM Test Method D1500.

The feedstock was then changed to a crystalline .wax having a melting point of F. and the temperature lowered to 550 F. The crystalline wax feedstock had a colour of 20.0Y using a Lovibond 18-inch cell. 16 hours after the change of feed the colour was 2.8Y and at 48 hours it was 1.1Y. The desired colour of 0.6Y was not achieved until hours after changeover.

The run was repeated again, starting with the microcrystalline wax feedstock using the same conditions. At the changeover to 120/ 125 F. melting point crystalline wax the temperature was, however, raised to 700 F. and the reactor pressure lowered to 400 p.s.i.g. These conditions were held for 20 hours after which the temperature was lowered to 550 F, and the pressure raised to 800 p.s.i.g. The desired colour of 0.6Y was achieved within 40 hours of the changeover of feedstock.

EXAMPLE 2 A hydrocatalytic process for the refining of lubricating oils used the following catalyst:

Percent wt. Iron oxide (Fe o 10.8 Molybdenum oxide (M 8.5 Cobalt oxide (C00) 2.3 Alumina Balance Various grades of solvent treated lubricating oils were treated, over a period of 1 month, under the following conditions:

Total pressure-400 p.s.i.g.

Hydrogen partial pressure-300 p.s.i.g. Feedstock space velocity--0.7-1.0 v./ v./ hr. Hydrogen flow rate36:1 v./v.

Prior to the change of feedstock to a non-solvent treated oil a solvent treated grade of lubricating oil having a viscosity of 11.0 cs. at 210 F. and a viscosity index of 95 was passed over the catalyst at a temperature of 535 F. for 4 days. The feedstock and product colours, as measured by ASTM Test Method D1500 were, respectively, 4.0 and L1.5.

The feedstock was then changed to a nonsolvent treated spindle oil having a viscosity of 9.2 cs. at 140 F. and the temperature lowered to 525 F. The spindle oil feedstock had a colour of 2.5 (ASTM D1500) but the colour of the product immediately after the changeover was 3.5 (i .e., worse than that of the feedstock). The product colour gradually improved with time but the desired product colour of 1.0 ASTM was not achieved until 48 hours after changeover.

In subsequent changeovers from solvent treated oil to nonsolvent spindle oil it was found that the colour stability of the spindle oil (obtained by measuring the colour after storage at 185 F.) was also poor immediately after changeover and only gradually improved as shown by the attached graph, the figure. In this graph curve 5 represents the desired colour stability obtained after a prolonged run on spindle oil alone and it will be seen that this colour stability is only approached and even then not reached 36 hours after changeover.

To avoid this undesirable state of affairs, the run was repeated. At the changeover from the solvent treated grade of oil a straight run vacuum gas oil (ASTM boiling range 250 to 370 C.) was substituted for the solvent treated grade and the temperature was raised to 635 F. for 24 hours. The gas oil space velocity was 0.5 v./v./hr. and the hydrogen partial pressure 300 p.s.i.g. At the end of this period the feedstock was changed to the nonsolvent treated spindle oil at 0.7 v./v./hr. and the temperature lowered to 525 F. The spindle oil colour and colour stability were, respectively, 0.9 ASTM, 0.15 C.D.I. giving a specification product immediately.

Colour Density Increase (specification 0.2 max).

What we claim is:

1. A process for the hydrocatalytic refining of waxes or lubricating oils in the presence of hydrogen and a hydrogenation catalyst, at a temperature in the range 450- 675 F., a hydrogen partial pressure of from 16 to 100 atmospheres, a liquid hourly space velocity of from 0.1 to 6 v./v./hr., and a hydrogen flow rate of from 1 to 150 v./v. of feedstock, in which the feedstock is changed from a microcrystalline wax as a first feedstock to a crystalline wax as a second feedstock, or from a solvent-treated grade of lubricating oil as a first feedstock to a nonsolvent-treated grade of lubricating oil as a second feedstock, said process being characterized in that the changeover is effected by discontinuing the passage of the first feedstock while continuing the passage of hydrogen, substituting a gas oil or a non-solvent treated grade of lubricating oil when the first feedstock is a solvent-treated grade of lubricating oil, or substituting crystalline wax when the first feedstock is a microcrystalline wax, raising the processing temperature for the substituted feedstock to above that used for the first feedstock, up to a maximum of 750 F. for a period of from 5 to 50 hours, then lowering the processing temperature to the normal processing temperature, and thereafter commencing processing of the second feedstock.

2. A process as claimed in claim 1 in which the first feedstock is a solvent-treated grade of lubricating oil, the substitute feedstock is a gas oil, and the second feedstock is a nonsolvent-treated grade of lubricating oil.

3. A process as claimed in claim 1, in which the first feedstock is a solvent-treated grade of lubricating oil, the substituted feedstock is a nonsolvent-treated grade of lubricating oil, and the second feedstock is also a nonsolvent-treated grade of lubricating oil.

4. A process as claimed in claim 1 in which the first feedstock is a microcrystalline wax, the substituted feedstock is a crystalline wax, and the second feedstock is also a crystalline wax.

5. A process as claimed in claim 4, wherein the pressure is lowered to between 1 to 27 ats. and below that of the processing pressure during the period of operation at raised temperature.

6. A process as claimed in claim 1 wherein the pressure is from 27-67 ats., the space velocity from 0.2 to 4 v./v./hr. and the hydrogen flow rate from 15 to 50 v./v.

7. A process as claimed in claim 1 wherein the temperature for microcrystalline wax is from 575 to 675 F. and for crystalline wax from 475 to 575 F.

8. A process as claimed in claim 1 wherein the temperature for solvent treated grades of lubricating oil is from 450 to 550 F. and for nonsolvent treated grades of oil from 450 to 535 F.

9. A process as claimed in claim 1 wherein the catalyst comprises one or more hydrogenating metals from Groups VIa or VIII of the Periodic Table on a support.

10. A process as claimed in claim 9 wherein the catalyst comprises molybdenum oxide and one or more iron group metals supported on alumina.

References Cited UNITED STATES PATENTS 3,089,841 5/ 1963 Berkowitz et al 20827 3,094,480 6/ 1963 Richardson 208216 3,228,875 1/ 1966 Demeester 208264 3,288,704 11/ 1966 OHara et a1 208264 3,365,385 1/1968 Kay et al. 20827 DANIEL E. WYMAN, Primary Examiner P. E. KONOPKA, Assistant Examiner US. Cl. X.R. 20818, 264

mg?" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,532,619 Dated October 6, 1970 Inventor(a) Howard Rees and Brian Linwood Wright It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 25, for "lub" read --1ube--;

Column 2, line 9, for "my" read --may--;

Column 2, line 40, for "feedstock" (second occurrence) read ----feedstock,--;

Column 3, line 37, for "paticularly" read --particu1ar1y--;

Column 3, line 68, for "consist" read --consists-;

Column 5, line 5, for "(Fe O read --(Fe 03)--.

ZLIEGNED W f JL'ED F-EB231971 ISEAL) Ana:

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