Catalyst – solid sorbent – or support therefor: product or process – Zeolite or clay – including gallium analogs – And additional al or si containing component
Reexamination Certificate
2002-02-19
2004-11-02
Stoner, Kiley (Department: 1725)
Catalyst, solid sorbent, or support therefor: product or process
Zeolite or clay, including gallium analogs
And additional al or si containing component
C502S074000, C502S064000
Reexamination Certificate
active
06812180
ABSTRACT:
BACKGROUND OF THE INVENTION
(i) Field of the Invention
The present invention relates to an improvement of a method for preparing a catalyst.
More specifically, the present invention relates to a method for preparing a catalyst, particularly a platinum-supporting halogen-treated L-type zeolite catalyst in which active components are supported on a carrier, and in this method, a drying treatment is carried out so that an evaporation rate of water from the whole surfaces of catalyst particles may be uniform in a drying treatment step, to homogeneously highly disperse the active components in the carrier and to thereby improve a catalytic activity.
(ii) Description of the Related Art
Heretofore, as catalysts for aromatizing non-aromatic hydrocarbons such as aliphatic hydrocarbons to produce aromatic hydrocarbons, platinum-aluminum catalysts have been used. However, these catalytic systems have a drawback that hydrocarbons having 6 and 7 carbon atoms cannot effectively be converted into the aromatic hydrocarbons.
Thus, in recent years, as a catalyst in which this drawback has been overcome, there has been found a catalyst in which platinum is supported on an L-type zeolite (Japanese Patent Publication No. 57408/1983). In this catalyst, a metal in the group VIII of the periodic table is supported on the L-type zeolite, but its activity is not sufficient and its life is inconveniently short. Afterward, for the sake of the improvement of the activity, a selectivity and the catalytic life and the simplification of a catalyst preparation method, various techniques have been suggested. For example, there have been suggested (1) a method which comprises supporting a metal in the group VIII on an L-type zeolite, and then subjecting it to an oxy-chlorination treatment to improve the catalytic activity and the life (Japanese Patent Application Laid-open No. 168539/1985), (2) a method which comprises treating an L-type zeolite with a solution containing a platinum salt and a non-platinum salt to improve platinum dispersion (Japanese Patent Application Laid-open No. 138539/1986), (3) a catalyst in which platinum is supported on an L-type zeolite treated with a halogen-containing compound (Japanese Patent Application Laid-open No. 57653/1987), (4) a catalyst in which platinum is supported on an L-type zeolite treated with a halogen-containing compound (Japanese Patent Application Laid-open No. 91334/1988), and (5) a simple catalyst preparation method which comprises the step of simultaneously supporting a platinum component and one or more halogen components on an L-type zeolite (Japanese Patent Application Laid-open No. 49936/1993).
However, the above method (1) has a drawback that a treating apparatus is complex, and the method (2) has a drawback that the catalytic activity is not sufficient. In addition, the catalysts of the above (3) and (4) make use of Freon which is a harmful substance in a halogen treatment, and they have a drawback that a high-temperature treatment is carried out, so that dealumination takes place and hence a surface area decreases. Moreover, in the above preparation method (5), there is a drawback that the obtained catalyst has a high cracking activity.
As understood from the foregoing, each of the conventional catalysts in which platinum is supported on the L-type zeolite has the disadvantage, and for the reason, they have not been always sufficiently satisfactory.
In this connection, it is known that in order to improve the activity of the obtained catalyst in the preparation of the catalyst in which the active component is supported on the carrier, the uniform and high dispersion of the active component on the carrier is important.
SUMMARY OF THE INVENTION
The present invention has been developed under such circumstances, and an object of the present invention is to provide a method for preparing a catalyst having an improved catalytic activity in which active components are supported on a carrier, particularly a method for preparing a platinum-supporting halogen-treated L-type zeolite catalyst which is desirable as a catalyst for the production of aromatic hydrocarbons and as a catalyst for the production of a gasoline and which can inhibit a cracking activity, can restrain the formation of coke (i.e., can restrain the deactivation of the catalyst by the coke), and can also improve an aromatic selectivity and a liquid yield.
The present inventor has intensively researched to achieve the above object, and as a result, it has been found that in a method which comprises impregnating a carrier with active components, drying the impregnated carrier, and then calcining the same to prepare a catalyst, the active components can uniformly and highly be dispersed and a catalytic activity can be improved by drying the impregnated carrier, i.e., the catalyst particles while they are always moved so that an evaporation rate of water from the whole surfaces of these catalyst particles may be uniform in the drying treatment step. In particular, it has been found that when a platinum-supporting halogen-treated L-type zeolite catalyst is prepared using an L-type zeolite as the carrier and using a platinum-containing compound and a halogen-containing compound as the active components, there can finally be obtained the catalyst in which the distribution of the halogen component is uniform, the platinum component is highly dispersed, an aromatizing activity can be improved, and a cracking selectivity deteriorates, by drying the catalyst particles while they are always moved. The present invention has been completed on the basis of such a knowledge.
That is to say, the present invention is directed to a method for preparing a catalyst which comprises the steps of impregnating a carrier with active components, drying the impregnated carrier, and then calcining the same, said drying treatment being carried out while the impregnated carrier is in a drifting condition. In particular, the present invention is directed to a method for preparing the catalyst wherein the carrier is an L-type zeolite, the active components are a platinum-containing compound and one or more halogen-containing compounds, and the obtained catalyst is a platinum-supporting halogen-treated L-type zeolite catalyst.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In a preparation method of a catalyst according to the present invention, when the catalyst is prepared by impregnating a carrier with active components, and then subjecting this impregnated carrier to a drying treatment step and a calcination step, the above drying treatment of the impregnated carrier is carried out in a condition that the impregnated carrier is drifty, i.e., in a condition that the impregnated carrier is freely movable.
By conducting the drying treatment in such a condition, it can be presumed that an evaporation rate of water from the whole surfaces of the respective particles of the catalyst is uniform. For example, with regard to one certain catalyst particle, if this catalyst particle is fixed in the drying treatment step, water is scarcely evaporated from portions of the catalyst particle which are in contact with adjacent catalyst particles, but water is easily evaporated from the other portions of the catalyst particle which do not contact them. That is to say, in the one catalyst particle, the portions having the different drying rates are present. However, when the catalyst particles are always moved as in the present invention, the positions of the portions which contact the adjacent catalyst particles and the portions which do not contact them always change, so that the evaporation rate of water from the whole surface of the one catalyst particle is substantially uniform, whereby the active components can be homogeneously highly dispersed and hence a catalytic activity can be improved.
As techniques for drying the impregnated carrier in such a drifty condition, there are a method of doing the drying treatment while a drying container containing the impregnated carrier is rotated, and a method of doing the drying treatment whil
Carroll Rodney B.
Conley & Rose, P.C.
Idemitsu Kosan Co. Ltd.
Ildebrando Christina
Reed K. KaRan
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