High-loading supported catalysts

Fig. 9.1. Effect of catalyst load and the presence of a support on the sintering of a catalyst, a) Unsupported powdered catalyst b) high load supported catalyst c) low load supported catalyst.

Dendritic Polymers as High-Loading Supports for Catalysts I 331... 

The above discussion has indicated that precipitation onto a suspended support is often required to produce catalysts in which the support is highly loaded. Highly loaded supports are especially desirable for catalysts containing (compounds of) base metals as mentioned... 

Impregnation has been used to prepare a number of catalysts having different metal support combinations. Highly loaded nickel catalysts supported on alumina, titania, silica, niobia and vanadium pentoxide were prepared by adsorption of nickel nitrate from an ammoniacal solution onto the support material. The supported salts were dried at 120°C and calcined at 370°C before reduction to the supported metallic nickel. It was found that the ease of reduction depended on the crystallinity of the support. Amorphous or poorly crystalline supports made the reduction of the nickel oxide more difficult than on crystalline supports. As examples of its generality, this procedure was also used to prepare... 

Preparation of Ultra High Loading Supported Pt Catalyst for Direct Methanol Fuel Cell... 

Contrary to the catalytic systems employed for the epoxidation, meehanistie studies of asymmetric ring opening have shown that eooperative interactions between eatalyst imits are needed [209]. Thus, high local concentration of catalyst was necessary and high-loading support should increase the catalytic reactivity. 

In a former study, we have prepared very highly loaded nickel catalysts, efficient for the hydrogenation of edible oil, by a (DP) method and examined the influence of the carrier surface area on the metallic dispersion and on the metal interaction with the silica. The best activity in soybean oil hydrogenation was obtained using a macroporous support with an intermediate surface area, the FC Celite (Manville) (16). We also observed that precipitate aging, at the end of the (DP) method, induced important modifications in the textural properties of the catalysts. 

Porosity and Pore Size. The support porosity is the volume of the support occupied by void space and usually is described in units of cm /g. This value represents the maximum amount of Hquid that may be absorbed into the pore stmcture, which is an especially important consideration for deposition of metal salts or other active materials on the support surface by Hquid impregnation techniques. The concentration of active material to be used in the impregnating solution is deterrnined by the support porosity and the desired level of active material loading on the catalyst. If the porosity is too low, inefficient use of the support material and reactor volume may result. If the porosity is too high, the support body may not contain sufficient soHd material to provide the strength necessary to survive catalyst manufacture and handling. 

Selective hydrogerration over low-loading, supported Cu catalysts has shown to be a valuable tool for the production of high quality biodiesel from Tall Oil, a byproduct of the Pulp Paper indrrstry. These resrrlts allow planning the use of a great variety of non-conventiorral oils with high iodine value for the production of biodiesel. 

---