Catalyst preparation particle drying

Influence of catalyst preparation, composition, and structure on activity and selectivity. There is an extensive literature some of which has been covered incidentally already. An excellent review has been published by Ripperger and Saum. Much of the work relates to the catalysts as oxides and so will not be covered in detail in this Report. Variables that influence catalytic properties include preparation e.g., method and order of addition of active components), pretreatment (drying and calcination,pre-reduction sulphiding,composition (e.g., concentration and ratio of active components and the type of support), distribution of active components in catalyst particles,particle size, " and surface area and pore size distribution. 

The mimic is prepared by sequential ion-exchanges with iron(ll) and Pd(ll) tetrammine cations followed by calcinations and reduction of the Pd(ll) to Pd(0) as previously described(14). A material with 2wt% Fe(ll) and 1wt% Pd(0) is used by immersing the dry zeolite solid in neat substrate alkane and then pressuring the reaction vessel with a 3 1 mixture of oxygemhydrogen. After shaking this mixture at room temperature for 4 hours the products are analyzed by capillary GC. As a control to assess the intrinsic selectivity of such a Pd/Fe system in the absence of steric effects of the zeolite, catalysts prepared with amorphous silico-aluminate supports were run for comparison. In these cases all reactions must take place at the particle surface since there is no interior pore structure available. In addition, comparison of reaction selectivities of this catalysts with our zeolite materials allows us to ascertain that the Fe active sites must be actually inside (and not on the exterior surface) of the zeolite crystallites. 

The Supported Sr-promoted La203 catalysts with different Sr/La ( 0.0, 0.03, 0.3, 2.0, 10.0) ratios and with Sr-La203 loading of 16 1.5 wt% were prepared by impregnating 22-30 mesh size particles of commercial low surface area porous, inert catalyst carrier ( SA-5205 obtained from Norton Co., USA) by the active catalyst mass. The impregnation of mixed nitrates of Sr and La from their aqueous solution on the support particles was done by the incipient wetness technique. The resulting supported catalyst mass was dried at 90°C for 16 h and then calcined in static air at 950°C for 4 h. 

---