Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Sulfur or compound containing same
Reexamination Certificate
1998-11-12
2001-09-18
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Sulfur or compound containing same
C502S020000, C502S034000, C502S219000, C502S220000, C502S221000, C502S313000, C502S315000, C502S321000, C502S327000
Reexamination Certificate
active
06291391
ABSTRACT:
FIELD OF INVENTION
This invention relates to an improved method of presulfiding a supported metal oxide catalyst for use in hydrotreating and/or hydrocracking hydrocarbon feedstocks, the presulfurized catalytic composition resulting therefrom, and a hydrotreating and/or hydrocracking process utilizing such presulfurized metal oxide catalyst. This invention further relates to an improved method for integrating catalyst presulfiding with a residuum hydroconversion process.
BACKGROUND OF THE INVENTION
A hydrotreating catalyst may be defined as any catalyst composition which may be used to catalyze the hydrogenation of hydrocarbon feedstocks to increase its hydrogen content and/or remove heteroatom contaminants. A hydrocracking catalyst may be defined as any catalyst composition which may be used to catalyze the addition of hydrogen to large or complex hydrocarbon molecules as well as the cracking of the molecules to obtain smaller, lower molecular weight molecules. A residuum hydroconversion process may be defined as a process for converting petroleum atmospheric or vacuum residue at conditions of elevated temperatures and pressures in the presence of hydrogen and a hydrotreating and/or hydrocracking catalyst to convert the feedstock to lower molecular weight products with reduced contaminant (such as sulfur and nitrogen) levels.
Catalyst compositions for use in the residuum hydroconversion process are well known to those skilled in the art and several are commercially available. Suitable catalysts include catalysts containing nickel, cobalt, tungsten, molybdenum and combinations thereof supported on a porous substrate such as silica, alumina, titania, or combinations thereof.
For maximum effectiveness these metal oxide catalysts are converted at least in part to metal sulfides. The metal oxide catalysts can be sulfided in the reactor by contact at elevated temperatures with hydrogen sulfide or a sulfur-containing oil or feedstock.
The catalysts may also be provided to the end-user already having sulfur incorporated therein. However, these ex-situ methods of presulfurizing supported metal oxide catalysts have suffered from excessive stripping of sulfur upon start-up of a hydrotreating reactor in the presence of a hydrocarbon feedstock. As a result of sulfur stripping, a decrease in catalyst activity is observed. It is therefore well known in the art that the activity and activity maintenance of the above mentioned metal oxide catalysts is substantially enhanced by presulfiding of the catalysts in the manufacturing process or in-situ during startup of the hydroconversion process.
Hydroconversion processes can operate in a fixed catalyst bed mode in which a batch of catalyst is utilized in the hydroconversion reactors for periods of typically three months to twenty-four months before the process is shut down to remove and replace the catalyst. In this fixed-bed mode, catalyst can be presulfided during unit startup to achieve maximum levels of catalytic performance (hydrogenation, desulfurization, denitrogenation, conversion, etc.)
In hydrotreating/hydrocracking processes, which add and withdraw catalyst on a regular basis (i.e. daily, weekly) while the process operates at normal conditions of temperature and pressure, catalyst is typically added in an as-manufactured state (i.e. containing metal oxides). Processes which operate in this mode include ebullated-bed hydrocrackers (such as H-Oil™ Process), moving-bed hydrotreater, Onstream Catalyst Replacement reactors (OCR) and guard reactors used in fixed-bed resid hydrotreaters.
In ebullated-bed processing applications, which utilize first generation low activity catalysts, minimal advantage has been identified for presulfiding the catalysts to be added on a daily basis. These catalysts achieve some presulfiding upon addition to the hydroconversion reactor. However, such operations that utilize new second and third generation catalysts (high desulfurization, low sediment), a significant increase in desulfurization, denitrogenation, and Conradson carbon removal can be achieved by presulfiding the catalyst additions.
The benefits of catalyst presulfiding in general are well known in the prior art. For example, the use of high boiling oils, such as vacuum gas oils, and hydrocarbon solvents to aid the incorporation of sulfur into a catalyst is taught in U.S. Pat. No. 4,943,547, issued Jul. 24, 1990. Further, U.S. Pat. No. 4,530,917, issued Jul. 23, 1985, to Berrebi discloses a method of presulfurizing a hydrotreating catalyst with organic polysulfides.
U.S. Pat. No. 4,117,136, issued Dec. 4, 1979, to Herrington et al discloses a method of catalyst presulfurizing wherein a catalyst is treated with elemental sulfur. Hydrogen is then used as a reducing agent to convert the elemental sulfur to hydrogen sulfide in situ. U.S. Pat. No. 4,089,930, issued May 16, 1978, to Kittrell et al discloses the pretreatment of a catalyst with elemental sulfur in the presence of hydrogen. All of the aforementioned patents are hereby incorporated by reference into this application.
This invention describes an improved method for achieving the catalyst presulfiding and preconditioning during normal plant operations but prior to addition of the catalyst to the catalytic reactor and can be accomplished in most situations with minimal equipment changes. This provides the benefit of being able to retrofit existing units as well as implementing on grass roots applications. Moreover, the invention allows for the preconditioning of the residuum hydrotreating or hydrocracking catalyst without interrupting the continuous operation of the resid hydroconversion process. Importantly, the resid hydroconversion process of this invention can operate continuously for several years while maintaining high catalyst activity.
SUMMARY OF THE INVENTION
It is an object of the present invention to presulfurize a hydrotreating and/or hydrocracking catalyst in a manner which maximizes the activity of the catalyst when added to the hydrotreating and/or hydrocracking reactor.
It is yet a further object of the present invention to prepare a safe, stable, presulfided hydrotreating and/or hydrocracking catalyst, either fresh or regenerated.
It is yet a further object of the present invention to provide a presulfided hydrotreating and/or hydrocracking catalyst that upon activation in-situ provides a highly active hydrotreating and/or hydrocracking catalyst.
It is yet another object of the present invention to provide a presulfided hydrotreating and/or hydrocracking catalyst that can be brought to severe hydrocracking conditions rapidly without rapid loss of activity.
It is another object of the invention to precondition the residuum hydrotreating or hydrocracking catalyst without interrupting the continuous operation of the resid hydroconversion process.
This invention describes an improved method for presulfiding and preconditioning a residuum hydrotreating or hydrocracking catalyst as an integrated part of the hydroconversion process. Moreover, the method allows for catalyst to be added onstream intermittently or continuously without interruption of the hydroconversion process. The method is used to condition, activate, or presulfide fresh or regenerated catalyst prior to its addition to the hydroconversion reactor utilizing product streams from the hydroconversion process.
Particularly, this invention describes a method to improve the activity and activity maintenance of a hydrotreating and/or hydrocracking catalyst utilized in a resid hydroconversion process comprising:
(a) exposing a metal oxide catalyst to H
2
S and H
2
rich streams within the hydroconversion process to at least partially convert the said metal oxide catalyst to a metal sulfide; and
(b) conditioning said catalyst by passing it through a liquid hydrocarbon stream; wherein the above steps are performed without interrupting the continuous operation of the resid hydroconversion process.
More specifically, this invention describes a method to improve the activity and activity maintenance of a hydrotreating and/or hydrocra
Bell Mark L.
Hailey Patricia L.
IFP North America, Inc.
Ritter John F.
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