Mineral oils: processes and products – Refining – With hydrogen
Reexamination Certificate
1999-11-16
2001-10-23
Yildirim, Bekir L. (Department: 1764)
Mineral oils: processes and products
Refining
With hydrogen
C208S2160PP, C208S25400R, C502S232000, C502S235000
Reexamination Certificate
active
06306289
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a hydrotreating catalyst and to a method of hydrotreating hydrocarbon oils using the same. More specifically, the present invention relates to a hydrotreating catalyst comprising a silica-alumina catalyst carrier in which the silica is highly dispersed or a silica-alumina carrier having a specific pore structure loaded with at least one type of hydrogenation-active metal component, and in particular, to one having a high degree of silica dispersion specified by nuclear magnetic resonance analysis; and to a method of hydrotreating hydrocarbon oils such as hydrodesulfurization, hydrodenitrogenation, hydrocracking, hydrodearomatization, hydroisomerization, and hydrofining using the same.
PRIOR ART
To date, there have been developed various hydrotreating catalysts for hydrotreating hydrocarbon oils in the process of producing petroleum products comprising a refractory inorganic oxide carrier such as alumina, silica-alumina, magnesia or zirconia loaded with oxides or sulfides of Group VI metals and Group VIII metals. These hydrotreating catalysts have been widely used, for example,in the hydrodesulfurization, hydrodenitrogenation, hydrocracking and hydrodearomatization of distallates and residual oils from the atmospheric or vacuum distillation of crude oils, the hydrofining of lubricating oil fractions, and the hydroisomerization of wax fractions.
However, there has been a demand in recent years from the viewpoint of environmental conservation for a further increase in desulfurization activity to meet the demand for more stringent hydrodesulfurization of hydrocarbon oils, together with a further increase in denitrogenation activity for the removal of nitrogen compounds in fuels which are seen as a source of nitrogen oxides which are substances which cause atmospheric pollution. Furthermore, when hydrocarbon oils which contain nitrogen compounds are subjected to catalytic cracking or catalytic reforming in the process of refining oils, there is a striking reduction in the activity of the cracking catalyst or reforming catalyst inviting a reduction in product yield, and there has therefore been a demand for increased denitrogenation activity to counter this problem.
Such a hydrotreating catalyst is disclosed, for example, in Japanese Patent Application Laid-open (Kokai) No. 287446/1986. It discloses a catalyst carrier composition having heat resistance and obtained by adding a basic compound to a mixed aqueous solution of an alumina hydrate and colloidal silica to convert the mixed aqueous solution into a viscous gel, followed by drying and calcinating the gel. In Japanese Patent Application Laid-open (Kokai) No. 242639/1986, there is disclosed a monolithic catalyst carrier comprising a structural layer of a sintered ceramic substance and a high surface area carrier layer of a porous oxide integrated with the structural layer. The porous oxide carrier layer of this catalyst has 50 to 93% by weight of alumina and 7 to 50% by weight of silica as its main components.
Furthermore, as proposals concentrating on the porous structure of the catalyst, there is disclosed, for example, in Japanese Patent Publication (Kokoku) No. 31496/1991 a hydrotreating catalyst comprising a silica-alumina carrier having a specific pore volume and a controlled distribution of pores in both the micropore and macropore regions, loaded with a hydrogenation-active component. In Japanese Patent Application Laid-open (Kokai) No.276712/1997, there is disclosed a catalyst comprising a carrier containing alumina, silica and magnesia loaded with Group VI and/or Group VIII metals, which has an average pore diameter of 190 to 350 Angstroms. In Japanese Patent Application Laid-open (Kokai) No.89806/1996, there is disclosed a hydrodesulfurization-denitrogenation catalyst comprising a carrier loaded with hydrogenation-active components, said carrier having a boria-silica-alumina base, having an average pore diameter of 60 to 90 Angstroms and in which the volume of pores having a pore diameter within ±10 Angstroms of the average pore diameter represents no less than 60% of the total pore volume.
However, each of the above-described proposed catalysts have the problem that their hydrogenation activity is still not sufficient. There is therefore the desire for the development of a hydrotreating catalyst which is improved with respect to desulfurization activity, denitrogenation activity, and with respect its performance at maintaining these activities.
DISCLOSURE OF THE INVENTION
An object of the present invention is to improve the above-mentioned problem areas of the prior art technology and to provide a hydrotreating catalyst which exhibits both high desulfurization activity and high denitrogenation activity and which is excellent with respect to its performance at maintaining these activities.
A second object of the present invention is to provide a hydrotreating catalyst which comprises a silica-alumina carrier in which the silica is highly dispersed and which has high desulfurization activity and high denitrogenation activity.
A third object of the present invention is to provide a hydrotreating catalyst in which hydrogenation-active metal components are highly dispersed on a carrier, and which is excellent with respect to both desulfurization activity and denitrogenation activity.
A fourth object of the present invention is to provide a method of hydrotreating to a high degree hydrocarbon oils containing sulfur and nitrogen compounds.
The inventors of the present invention have carried out extensive research regarding the relationship between the desulfurization activity and denitrogenation activity of a hydrotreating catalyst and the physical properties of its carrier. As a result, they found that when silica-alumina comprising a silica layer formed on an alumina surface is used as the carrier, the control of the solid acidity of the hydrotreating catalyst is facilitated, and that the increase in silicon-aluminum bonds and the uniform development of a number of solid acid sites having uniformly acidic properties on the alumina is facilitated; and that as a result both the sulfur compounds and nitrogen compounds in a hydrocarbon oil can be eliminated to a high degree by using a hydrotreating catalyst having as a structural component a silica-alumina carrier which contains a large amount of silica and in which the silica is highly dispersed or a silica-alumina-third component carrier comprising silica, alumina and a third component which has a high pore volume in the relatively small pore diameter regions and whose pore diameter distribution lies within a specific range. It was on the basis of these findings that the present invention was completed.
The present invention provides a hydrotreating catalyst comprising a carrier comprising silica and alumina loaded with at least one hydrogenation-active metal component, characterised in that:
(1) the silica content is in the range of 2% to 40% by weight based on the total weight of the catalyst carrier; and
(2) in the spectrum obtained by nuclear magnetic resonance analysis (
29
Si-NMR),
(i) the area of peaks at −80 ppm is 10% or more of the combined area of all the peaks, and
(ii) the total area of peaks at −80 ppm, −86 ppm and −92 ppm is 20% or more of the combined area of all the peaks.
The present invention also relates to a hydrotreating catalyst comprising a carrier comprising silica and alumina and containing an alkaline earth metal oxide and/or boria as a third component, loaded with at least one hydrogenation-active metal component, wherein:
(1) the silica content is in the range of 2% to 40% by weight based on the total weight of the carrier;
(2) the content of the third component is in the range of 0.1 to 10% by weight based on the total weight of the carrier; and
(3) in the pore structure:
(i) the ratio ((a)/(b)) of (a) the volume of pores having a pore diameter in the range of 30 to 100 Angstroms as measured by the nitrogen adsorption method and (b) the volume of pores havin
Hayashi Fumitaka
Kamo Akira
Toshima Hiroshi
Birch & Stewart Kolasch & Birch, LLP
Tonen Corporation
Yildirim Bekir L.
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