摘要:
The invention relates to a process and to an apparatus for preparing a heterogeneous catalyst having at least one catalytically active species bound to the surface of a support material. According to the process, the surface of the support is first pretreated. A catalyst reagent containing the catalytically active species or its precursor is vaporized and the vapor is routed into a reaction chamber where it is brought to interact with the support material. The catalyst reagent not bound to the support is withdrawn from the reaction chamber in gaseous form. If necessary, the species bound to the support is posttreated in order to convert it into a catalytically active form. According to the invention, the amount of catalyst reagent brought into the reaction chamber is at least equal to, preferably in excess of the number of available binding sites on the surface. The temperature of the support of kept higher than the condensation temperature of the vapor and at the same time at a sufficiently high level to attain the thermal activation energy needed for forming bonds between the active species and the support. By binding the catalytically active species in this way to the support it is possible to provide a heterogeneous catalyst having a high activity even at small amounts of the active species.
摘要:
The present invention concerns a heterogenic catalyst suited to the metathesis reactions of hydrocarbons in particular. Such a catalyst includes an inorganic oxide support, typically consisting of .gamma.-alumina, having rhenium oxide absorbed onto its surface. The catalyst in accordance with the invention is prepared by vapourizing a precursor of rhenium, preferably rhenium heptoxide, preferably at a temperature of at least 160.degree. C., and routing the vapour into a reaction chamber where they are brought to interaction with the support material. The temperature of the support material is kept above the condensation temperature of the vapour and simultaneously sufficiently high so as to attain the thermal activation energy level necessary for the generation of bonds between the rhenium oxide and the support material. According to the invention, the process is carried out preferredly within a temperature range of approx. 160.degree. . . . 500.degree. C. The rhenium oxide precursor is introduced in vapour phase in an amount, which is at least equal to or, preferably, in excess of the number of available binding sites on the support material surface. The activity of a catalyst even with a very low content of catalytic metal species is as high as the activity of a catalyst of appreciably higher content of rhenium that has been prepared by the methods of conventional technology.
摘要:
The present invention concerns a method for preparing heterogeneous catalysts. According to the method, preparation is carried out under such process conditions in which the bonding of compounds from the gas phase onto the surface of a support material is primarily determined by the properties of the support surface. The constituents contained in the reagent are then selectively bonded to the bonding sites of the support material surface, thus forming stable surface bonds. According to the invention, the number of surface-bond sites available for preparing a stable product with surface bonds is controlled by varying the reaction temperature and/or selecting a suitable reagent. The invention makes it possible to control the metal content of the end product at a predetermined level.
摘要:
Provided are heterogeneous catalysts for homo- and copolymerization of olefins as well as a method for preparing these catalysts, which comprise at least one metallocene compound of a Group 4A, 5A or 6A (Hubbard) transition metal on a solid inorganic support. The method comprises the steps of vaporizing the metallocene compound, treating the support material with the vaporized metallocene compound at a temperature which is sufficiently high to keep the metallocene compound in the vaporous state, contacting the support material with an amount of the vaporized metallocene compound which is sufficient to allow for a reaction between the metallocene compound and at least a substantial part of the available surface sites capable of reacting therewith, removing the rest of the metallocene compound not bound to the support, and optionally treating the product thus obtained with an activating agent. The catalysts are active even if very low amounts of activator agents, such as alumoxane, are used. Furthermore, the polymerization performance of the catalysts can be regulated during the preparation of the catalysts. Thus, by using different support pretreatment temperatures, or by using two or more different metallocenes, and by altering the order in which they are added on the support, it is possible to control and regulate the activity of the catalysts and the polymer properties, such as molecular weight and molecular weight distribution.
摘要:
The present invention concerns heterogeneous catalysts for polymerization of olefins. The catalysts include at least one Group IVa metal compound on a solid inorganic oxidic support. According to the invention the catalysts are prepared by vapourizing at least one solid Group IVa metal halide compound and routing the vapour of the metal halide compound into a reaction chamber, wherein the vapour is reacted with the support at a temperature of about 250.degree. to about 450.degree. C. in order to bind said metal halide compound to said support. Any metal compound not bound to said support as well as any volatile reaction products emanating from the reaction between said metal halide compound and said support are then removed from the reaction chamber in the vapour phase. Optionally, the product obtained is treated with an organic aluminum compound to increase the catalytic activity of said catalyst. The catalysts thus prepared are very well suited for polymerization of ethylene or copolymerization of ethylene with other alpha-olefins, such as propylene, butylene, 4-methyl-1-pentene and hexene. A polymerization process employing the novel catalyst will provide products of the Ultra High Molecular Weight-type (UHMWPE) having very broad MWD.
摘要:
Provided are heterogeneous catalysts for homo- and copolymerization of olefins as well as a method for preparing these catalysts, which comprise at least one metallocene compound of a Group 4A, 5A or 6A (Hubbard) transition metal on a solid inorganic support. The mtehod comprises the steps of vaporizing the metallocene compound, treating the support material with the vaporized metallocene compound at a temperature which is sufficiently high to keep the metallocene compound in the vaporous state, contacting the support material with an amount of the vaporized metallocene compound which is sufficient to allow for a reaction between the metallocene compound and at least a substantial part of the available surface sites capable of reacting therewith, removing the rest of the metallocene compound not bound to the support, and optionally treating the product thus obtained with an activating agent. The catalysts are active even if very low amounts of activator agents, such as alumoxane, are used. Furthermore, the polymerization performance of the catalysts can be regulated during the preparation of the catalysts. Thus, by using different support pretreatment temperatures, or by using two or more different metallocenes, and by altering the order in which they are added on the support, it is possible to control and regulate the activity of the catalysts and the polymer properties, such as molecular weight and molecular weight distribution.
摘要:
The present invention concerns a polymerization catalyst of olefins, said catalyst containing an active chromium compound on an inorganic support. The catalyst in accordance with the invention is prepared by vaporizing a precursor of chromium oxide such as chromyl chloride and allowing the chromium oxide vapor to react with the surface of, e.g., silica gel support material at 160.degree. . . . 500.degree. C. A selective binding of the chromium oxide to the support material is achieved by keeping the vapor pressure sufficiently high and the duration of interaction with the support sufficiently long so as to maintain an excess of the chromium compound in relation to the number of available binding sites on the support material. The activity of a catalyst in accordance with the invention even with a very low content of catalytic metal is as high as the activity of a catalyst of an appreciably higher metal content that has been prepared by the methods of the conventional technology.
摘要:
The present invention concerns a catalyst for the polymerization of olefins, and a method for preparing the same said catalyst constituting an inorganic support material with catalytically active chromium and titanium compounds bound on its surface. The catalyst is prepared according to the invention by bringing the catalytically active metal compounds sequentially in vapor phase onto the support material surface in excess amounts in relation to the binding sites available on the support material surface. The support material temperature is maintained above the condensation temperature of the vapor, preferably above 160.degree. C., and simultaneously sufficiently high so as to achieve the thermal activation energy necessary for the generation of bonds between the support material and the catalytically active material or its compound. To avoid desorption of the chemisorbed compounds, the temperature is kept below approx. 500.degree. C. The activity of a catalyst in accordance with the invention even with very low contents of the catalytic metals is as high as the activity of a catalyst of multiply higher metal contents that has been prepared by the methods of the conventional technoloyg.
摘要:
The present invention concerns a catalyst suited to the aromatization reaction of light hydrocarbons. Such a heterogeneous catalyst contains zinc bound to a zeolite support material. The catalyst in accordance with the invention is prepared by adsorbing the zinc onto the surface of the zeolite support material directly from the vapor phase by way of chemisorption. The zeolite compound acting thus as the support material is here heated to a temperature which is above the condensation temperature of the zinc vapor. Advantageously, the preparation has been carried out at temperatures above 390.degree. C. The zinc vapor has been brought to contact the zeolite support material, whereby the vapor pressure of zinc is maintained sufficiently high and the duration of its interaction with the support material sufficiently long so as to provide at least one equal amount of or, preferably, an excess of zinc in relation to the available binding sites of the support material. In order to avoid the desorption of absorbed zinc, temperature in the preparation reaction of the catalyst in accordance with the invention has been maintained below 550.degree. C.