Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Silicon containing or process of making
Reexamination Certificate
2001-07-02
2004-01-27
Silverman, Stanley S. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Silicon containing or process of making
C502S327000
Reexamination Certificate
active
06683020
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and composition for opening naphthenic rings of naphthenic ring-containing compounds. In particular, this invention relates to the use of a catalyst composition comprising Ir on a composite support of alumina and an acidic silica-alumina molecular sieve.
BACKGROUND OF THE INVENTION
Ir-containing ring opening catalysts are useful in converting multi-ring aromatics by reduction to naphthenes, and then ring opening the naphthenes to paraffins. For example, in U.S. Pat. No. 5,763,731, a ring opening catalyst is disclosed which contains a metal function and an acid function. The metal function is supplied by Ir, Ru, or Rh. The acid function, supplied by a zeolitic material, is effective for isomerizing six-membered naphthenic rings to five-membered naphthenic rings. The metal function is effective for ring opening naphthenic rings, particularly the five-membered naphthenic rings. Paraffin content of diesel, jet fuel, and heating oil, as well as light cycle oil, compositions can be creased in a variety of ways in order to increase cetane number. For example Ir catalysts have been shown to be highly effective in ring opening naphthene ring-containing compounds contained in diesel, jet fuel, heating oil, and light cycle oil compositions, which results in increased paraffin content and, therefore, higher cetane. See for example, U.S. Pat. No. 5,811,624. Such catalysts are useful for upgrading the quality of mid-distillate petroleum streams by providing improvements in gravity, volume, and cetane number. Further improvements, particularly higher cetane number, are nevertheless desired. Conventional IR-containing ring opening catalysts which have been used to ring open naphthene rings of naphthene ring-containing compositions found in diesel, jet fuel, heating oil, and light cycle oil compositions tend, however, to deactivate over time. It is believed that this deactivation is due to deposition of heavy carbonaceous residues on the catalyst during the ringing opening process. Removal of these residues would, therefore, be required to maintain, or restore, activity. Ideally, regeneration by a simple carbon burn in the presence of oxygen would be a desired method. There is also a desire to find a ring opening catalyst that can be regenerated for extended use.
SUMMARY OF THE INVENTION
In one embodiment, the invention relates to a ring opening catalyst comprised of Ir on a composite support of an alumina component and an acidic silica-alumina molecular sieve component. The catalyst is resistant to deactivation by calcination in air and provides higher activity than conventional Ir on alumina catalyst. In addition, the composite catalyst has lower cracking activity and superior gas/liquid selectivity.
In a preferred embodiment, the catalyst is a naphthene ring opening catalyst which comprises Ir on a composite support of alumina and acidic silica-alumina molecular sieve, with the acidic silica-alumina molecular sieve preferably having a Si/Al atomic ratio of at least about 30, more preferably at least about 40, most preferably at least about 60, prior to compositing with the alumina. Preferably, the composite support's alumina component is present in a range of from about 99 to about 1 wt. %, and the acidic silica-alumina molecular sieve component is present in a range of from about 1 to about 99 wt. %; more preferably the alumina component is present in a range of from about 95 to about 5 wt. %, and the acidic silica-alumina molecular sieve component is present in a range of from about 5 to about 95 wt. %; most preferably, the alumina component is present in a range of from about 90 to about 10 wt. %, and the acidic silica-alumina molecular sieve component is present in a range of from about 10 to about 90 wt. %. The weight percents are based on the weight of the composite support.
In another preferred embodiment, the catalyst further comprises at least one other or “second” Group VIII metal selected from Pt, Pd, Rh, or Ru. Preferably, the second Group VIII metal or metals is present in a range of from about 0.01 to about 5 wt. %; more preferably, the second Group VIII metal is present in a range of from about 0.01 to about 2.0 wt. %; most preferably, the second Group VIII metal is present in a range of from about 0.01 to about 1.0 wt. %. The weight percents are based on the weight of the ring opening catalyst.
In yet another preferred embodiment, the Ir is present in a range of from about 0.01 to about 2.0 wt. %. Preferably, Ir is present in a range of from about 0.1 to about 1.2 wt. %. Most preferably, Ir is present in a range of from about 0.01 to about 1.0 wt. %. The weight percents are based on the weight of the ring opening catalyst.
In another embodiment, there is provided a process for opening naphthene rings of naphthene ring-containing compounds in a feed stream. The process comprises providing a naphthene ring-containing feed stream; and contacting the naphthene ring-containing feed stream with the naphthene ring opening catalyst of this invention.
Ring opening can be carried out at a temperature ranging from about 150° C. to about 400° C.; a total pressure ranging from about 100 to about 3,000 psig; a liquid hourly space velocity ranging from about 0.1 to about 10 V/V/Hr; and a hydrogen treat gas rate ranging from about 200 to about 10,000 standard cubic feet per barrel (SCF/B).
In another preferred embodiment, the feed stream is a petroleum feed stream which has a boiling point of from about 175° C. to about 600° C.
In a preferred embodiment, the ring opening process further comprises ring opening naphthene rings containing at least one tertiary carbon site at the tertiary carbon site, thereby forming a ring opened product having increased linear paraffin functionality relative to that of the feed stream. The process can also include recovering the ring opened product. The ring-opened product may be used directly, for example, as a diesel fuel, jet fuel, gas oil and heating oil, and it may be blended with other petroleum streams for use, for example, as a diesel fuel, jet fuel, gas oil, and heating oil. Preferably, the ring opened product is blended with a petroleum stream having a boiling point of from about 175° C. to about 600° C., wherein the blend has a cetane number of at least about 40.
Desirably, the naphthene ring-containing feed stream has a sulfur content of less than about 10 ppm, preferably less than about 1 ppm, more preferably less than about 0.1 ppm. It is also desirable that the naphthene ring-containing feed stream contains less than about 20 wt. % total aromatic compounds.
In yet another preferred embodiment, there is provided a method of making a naphthene ring opening catalyst. The method comprises mixing together an alumina component and an acidic silica-alumina molecular sieve component. The mixture is then composited, and Ir is added to the composite to form a naphthene ring opening catalyst. Other Group VIII metals can also be added to the composite.
The invention also relates to a naphthene ring opening catalyst system which comprises a naphthene ring isomerizing catalyst containing a catalytically active naphthene ring isomerization metal supported on a first catalyst support in an amount effective to isomerize a C
6
naphthene ring-containing compound to a C
5
naphthene ring-containing compound. The catalyst system further comprises the naphthene ring opening catalyst comprising Ir on a composite support of alumina and silica-alumina molecular sieve, including the preferred embodiments thereof.
Also included as part of this invention are the products made by the stated processes.
DETAILED DESCRIPTION OF THE INVENTION
A major parameter in defining the value of diesel and jet fuel range products is cetane number. In general, the higher the cetane, the higher the quality of diesel and jet fuel range products.
While paraffins are typically high in cetane number, linear paraffins are generally higher in cetane number than branched paraffins having a corresponding number of carbons. Therefore,
Baird Jr. William C.
Chen Jingguang G.
Klein Darryl P.
McVicker Gary B.
ExxonMobil Research and Engineering Company
Hughes Gerard J.
Johnson Edward M.
Kliebert Jeremy J.
Silverman Stanley S.
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