Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Sulfur or compound containing same
Reexamination Certificate
2002-01-30
2004-05-18
Koslow, C. Melissa (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Sulfur or compound containing same
C502S222000, C502S223000, C502S325000, C502S349000, C423S544000, C423S545000, C423S608000, C423S625000
Reexamination Certificate
active
06737380
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a solid acid catalyst and a process for producing the same. More particularly, the present invention relates to a sulfate group-containing zirconia-alumina catalyst having loaded thereon a metal of the Group VIII which is suitable for industrial use, and to a process for producing the same. Also, the present invention relates to a method for hydrodesulfurizing and isomerizing a light hydrocarbon oil which is conducted using the catalyst.
BACKGROUND OF THE INVENTION
Solid acid catalysts, in particular, sulfate group-containing zirconia catalysts and having loaded thereon a metal of the Group VIII, are used for the isomerization or alkylation of hydrocarbons. Solid acid catalysts for industrial use including these catalysts should not only have high catalytic activity but also have strength to some extent so as not to be broken by their own weight when packed into reactors. Because of this, a technique which has hitherto been used frequently is to press a powdery solid acid catalyst as it is into tablets or mold the catalyst into columnar, four-cusped, spherical, particulate, or other shapes with an appropriate binder before the catalyst is packed into a reactor and used.
However, the tablet catalyst obtained by mere press forming is apt to break during the operation of the practical apparatus because it is a mere powder compact. In addition, since the tablets are not a porous material, inner parts of the catalyst cannot be utilized as a reaction field. Namely, the area of contact with reactants is small and this catalyst has low activity.
The technique using a binder for molding is effective in obtaining a porous catalyst having a high contact efficiency. However, since some degree of binder amount is necessary for securing a certain strength, the binder, when added in a large amount, reduces the concentration of the solid acid in the molded catalyst, resulting in reduced catalytic activity. Furthermore, there are cases where the binder itself deactivates active sites present on the catalyst surface to reduce the catalytic performance.
Examples of the proposed techniques using a binder include processes for producing a catalyst which comprise mixing zirconium hydroxide or zirconia with boehmite-state alumina as a binder and molding the mixture (JP-A-9-38494 and JP-A-11-57478). Although these processes can yield a porous catalyst having a high contact efficiency, the side crush strength of the catalyst cannot be sufficiently enhanced because the binding strength between the alumina as a binder and the zirconium hydroxide or zirconia as a raw material is low. Although increasing the amount of the alumina to be mixed as a binder is necessary for heightening the side crush strength, this results in an increase in the proportion of the alumina in the molded catalyst. Namely, the catalyst thus obtained has a low solid-acid content, i.e., low activity.
Another process comprises calcining zirconium hydroxide or zirconia having loaded thereon a sulfate group, and subsequently adding alumina as a binder thereto, followed by molding. However, the catalyst produced by this process has extremely low solid acidity because the alumina covers the sulfate group, and cannot hence be used as a practical catalyst.
Under these circumstances, how to produce a molded solid acid catalyst having a high side crush strength, a small binder amount, and hence high solid acidity from a powdery solid acid catalyst has been a subject of study in this field.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for producing a solid acid catalyst which has a high side crush strength and retains the inherent solid acidity even though it is a molded catalyst.
Another object of the present invention is to provide a method of hydrodesulfurization and isomerization by which the desulfurization and isomerization of an organosulfur compound-containing light hydrocarbon oil can be simultaneously attained with the solid acid catalyst produced by the process.
These and other objects of the present invention have been accomplished by a process for producing a solid acid catalyst, which comprises:
(A) subjecting a zirconium hydroxide to a sulfation treatment by adding a sulfate group-containing substance;
(B
1
) adding a pseudoboehmite as a binder to the sulfated zirconium hydroxide, followed by kneading with an aqueous solution containing at least one metal of the Group VIII;
(C) molding the resulting kneaded mixture; and
(D) calcining the resulting molding at a temperature of from 550 to 800° C.
Furthermore, these and other objects of the present invention have been accomplished also by a process for producing a solid acid catalyst, which comprises:
(A) subjecting a zirconium hydroxide to a sulfation treatment by adding a sulfate group-containing substance;
(B
2
) loading at least one metal of the Group VIII on the sulfated zirconium hydroxide, and then adding a pseudoboehmite as a binder thereto, followed by kneading with water;
(C) molding the resulting kneaded mixture; and
(D) burning the resulting molding at a temperature of from 550 to 800° C.
Moreover, these and other objects of the present invention have been accomplished with a solid acid catalyst, which is produced by any of the above processes, and has a specific surface area of from 50 to 200 m
2
/g, a total pore volume of from 0.05 to 0.5 mL/g, and a side crush strength of 0.3 kg/2 mm or higher.
Also, these and other objects of the present invention have been accomplished with a method for the hydrodesulfurization and isomerization of a light hydrocarbon oil, which comprises bringing a light hydrocarbon oil having a sulfur content of 700 ppm by weight or lower and hydrogen into contact with the above catalyst under reaction conditions at a temperature of from 160 to 240° C., a pressure of from 1.0 to 4.5 MPa, an LHSV of from 1.0 to 10 h
−1
, and a hydrogen/oil ratio of from 100 to 1,000 NL/L.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors made intensive investigations in order to overcome the drawbacks of the known techniques described above. As a result, it has been found that for producing a solid acid catalyst without adversely influencing the catalytic activity which should be inherent therein, it is essential that sulfate group-containing zirconium hydroxide is prepared first and catalyst production is carried out using the zirconium hydroxide as a starting material. It has further been found that a catalyst combining a high side crush strength and high activity in hydrodesulfurization and isomerization is obtained by using the sulfate group-containing zirconium hydroxide in the uncalcined state as a molding material and by adding a pseudoboehmite as a binder, followed by kneading, and calcining the kneaded mixture at from 550 to 800° C. The present invention has been thus completed.
The constituent elements of the present invention will be explained below.
Zirconium Hydroxide:
The zirconium hydroxide to be used in the present invention may be not only a hydroxide of zirconium but a partially oxidized hydroxide. Consequently, the term “zirconium hydroxide” or “hydroxide of zirconium” will be used in the following description as a representative of both. Zirconium hydroxide exists in several forms including Zr(OH)
4
, Zr(OH)
2
, Zr(OH)
3
and ZrO(OH)
2
, and any of these can be used. Zr(OH)
4
and ZrO(OH)
2
are preferred. The zirconium hydroxides may be hydrates. Zirconium hydroxides which are commercially available may be used. It is possible according to need to produce a zirconium hydroxide by a known method, e.g., a method in which a solution of a water-soluble salt of zirconium is made alkaline to thereby precipitate the hydroxide.
Sulfating Agent and Amount of Sulfate Group:
One feature of the present invention resides in that a sulfation treatment for incorporating a sulfate group into a zirconium hydroxide is conducted before the catalyst production proceeds. Examples of the treating agent which gives a sulfate group include sulfuric acid, a
Baba Koji
Kawakami Takahito
Kimura Takao
Watanabe Katsuya
Hailey Patricia L.
Koslow C. Melissa
Petroleum Energy Center
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