Catalytic dewaxing with trivalent rare earth metal ion...

Details Catalytic dewaxing with trivalent rare earth metal ion... Catalytic dewaxing with trivalent rare earth metal ion...

1999-10-12

2001-09-04

Myers, Helane (Department: 1764)

Mineral oils: processes and products

Paraffin wax; treatment or recovery

Chemical treatment

C205S111000, C205S057000, C205S067000, C205S089000

Reexamination Certificate

active

06284127

ABSTRACT:

BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
The invention relates to catalytic dewaxing with a rare earth metal ion exchanged ferrierite. More particularly the invention relates to catalytically dewaxing a waxy hydrocarbonaceous feed to reduce its pour point, using a dewaxing catalyst comprising ferrierite in which one or more trivalent rare earth metals occupy at least a portion of its cation exchange positions.
2. Background of the Invention
Catalytically dewaxing waxy hydrocarbonaceous materials such as paraffinic feeds to reduce their pour point and convert the wax to more useful products, such as fuel and lubricating oil fractions, is known. Such feeds have included petroleum derived wax containing oils, heavy oil fractions and slack wax. Dewaxing catalysts comprise a catalytic metal component, a natural or synthetic, crystalline aluminosilicate or zeolite molecular sieve component and often one or more additional refractory metal oxide components. Molecular sieves which have been found useful for dewaxing petroleum oil fractions and slack wax include, for example, ferrierite (U.S. Pat. Nos. 4,343,692 and 4,795,623), mordenite (U.S. Pat. No. 3,902,988), ZSM-23 and ZSM-35 (U.S. Pat. No. 4,222,855), ZSM-5 and ZSM-11 (U.S. Pat. No. 4,347,121) and ZSM-5 (U.S. Pat. No. 4,975,177).These various catalysts have different selectivities for different products. For example, while ZSM-5 is particularly effective for dewaxing lube oil raffinates, the cracking selectivity to gaseous products is high resulting in low lube yield. There is still a need for a dewaxing catalyst and process selective towards the production of lube oil base stocks, and particularly for premium, high purity and high VI lube oils with low pour points.
SUMMARY OF THE INVENTION
It has been found that ferrierite can be ion exchanged with trivalent rare earth metal using a hydrothermal ion exchange method and that a dewaxing catalyst comprising the rare earth exchanged ferrierite exhibits better overall selectivity for producing lube oil fractions having a low pour point and a high VI than the hydrogen form of either ferrierite or mordenite. Thus, the invention relates to a process for catalytically dewaxing a waxy hydrocarbonaceous material by reacting the material with hydrogen, in the presence of a catalyst comprising ferrierite in which at least a portion, preferably at least 10%, more preferably at least 15% and still more preferably at least 25% of its cation exchange capacity is occupied by one or more trivalent rare earth metal cations, under reaction conditions effective to reduce the pour point of the material. By rare earth metal is meant the lanthanide elements and includes La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and mixtures thereof Hereinafter, in the context of the invention “RE-ferrierite” is meant to include either natural or synthetic ferrierite in which at least a portion, preferably at least 10%, more preferably at least 15% and still more preferably at least 25% of the cation exchange capacity is occupied by one or more of these trivalent lanthanide elements. When used for catalytic dewaxing, at least one catalytic metal component effective for catalytic dewaxing is added to the RE-ferrierite. Such metal components will typically include at least one Group VIII metal and preferably at least one Group VIII noble metal. Further, the RE-ferrierite may be composited with other known catalytic components which are described in detail below. A dewaxing catalyst comprising RE-ferrierite of the invention to which has been added a Group VIII noble metal has been found to be particularly effective for producing high yields of dewaxed lubricating oil fractions of reduced pour point from Fischer-Tropsch wax that has been hydroisomerized to produce a mixture of iso-paraffins and normal paraffins. Prior to being catalytically dewaxed, hydrocarbon feeds derived from petroleum, shale oil, tar sands, and the like will be hydrotreated to remove sulfur and nitrogen compounds, aromatics and other unsaturates.
DETAILED DESCRIPTION
As set forth above, a typical dewaxing catalyst of the invention will comprise RE-ferrierite and also at least one catalytic metal component. The dewaxing catalyst of the invention is a dual function catalyst having both a hydroisomerization and a dehydrogenation-/hydrogenation function, with the RE-ferrierite providing the hydroisomerization function and the catalytic metal component the dehydrogenation/hydrogenation function. In one embodiment the catalyst will also contain one or more refractory catalyst support materials, including one or more additional molecular sieve components. The refractory catalytic support material may include, for example, any oxide or mixture of oxides such as silica which is not catalytically acidic and acid oxides such as silica-alumina, other zeolites, silica-alumina-phosphates, titania, zirconia, vanadia and other Group IIIB, IV, V or VI oxides. The Groups referred to herein refer to Groups as found in the Sargent-Welch Periodic Table of the Elements copyrighted in 1968 by the Sargent-Welch Scientific Company. A catalytic metal component, such as one or more Group VIII metals and preferably at least one noble metal of Group VIII, may be deposited on, ion exchanged into or composited with the RE-ferrierite or it may be supported on one or more refractory catalyst support materials or additional molecular sieve components that have been or will be composited or mixed with the RE-ferrierite. Thus, the catalytic metal, and promoter metal if present, is composited or mixed with, impregnated into, occluded or otherwise added to one or more of the other catalyst components either before or after they are all mixed together and extruded or pilled. In one embodiment it has been found to be effective to ion-exchange the catalytic metal (e.g., preferably a noble metal as Pt or Pd and preferably Pt) into the ferrierite. One or more metal promoter components of Groups VIB and VIIB may be used with the one or more Group VIII metal catalytic components. Typical catalytic dewaxing conditions useful in the process of the invention are set forth in the Table below.
Condition
Broad
Preferred
Temperature, ° F.
300-950
400-800
Total pressure, psig
250-3,000
500-1,500
LHSV
0.1-10
0.5-5
Hydrogen treat rate, SCF/B
500-15,000
1,000-3,000
An RE-ferrierite dewaxing catalyst of the invention may be used to dewax any waxy hydrocarbonaceous feed, including light and heavy petroleum oils, slack wax, Fischer-Tropsch wax and the like. Prior to being catalytically dewaxed, hydrocarbon feeds derived from petroleum, shale oil, tar sands, and the like will be hydrotreated to remove sulfur and nitrogen compounds, aromatics, and non-aromatic unsaturates. It is preferable to deoil such feeds prior to the hydrotreating to an oil content of from about 0-35 wt. % and preferably 5-25 wt. %. The hydrotreating step is accomplished by reacting the feed with hydrogen in the presence of any well known hydrotreating catalyst at hydrotreating conditions. Such catalysts typically comprise catalytic metal components of Co/Mo, Ni/Mo or Ni/Co/Mo on alumina and are well known to those skilled in the art. Typical conditions include a temperature in the range of from 540-750 F., a space velocity of 0.1 to 2.0 v/v/hr, a pressure of from 500-3,000 psig and hydrogen treat rates of from 500-5,000 SCF/B. Further, if desired the feed may also be hydroisomerized prior to catalytic dewaxing.
A dewaxing catalyst comprising the RE-ferrierite of the invention has been found to be particularly effective for producing dewaxed lubricating oil fractions of low pour point with high product yield from Fischer-Tropsch wax that has been hydroisomerized over a dual function catalyst to produce a heavy boiling feed comprising a mixture of iso-paraffins and normal paraffins. When produced via a slurry process from a catalyst which includes a cobalt catalytic component, this Fischer-Tropsch wax feed is very pure, typically having less than 1 wppm of either sulfur or nitrogen and comprising at l

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