Impregnation of catalysts

Very fine particles of iron sulfide is one class of very promising catalysts because of lower cost and moderate activity. Presulfiding treatments for activation, ion exchange, and dispersed impregnation of catalysts or catalyst precursors are combined to enhance the catalytic activity and reduce the amount of catalyst required (69, 70). 

An early attempt to simulate metals deactivation was the introduction of the Mitchell method steam deactivation procedure (2). This procedure involved impregnation of catalysts with Ni and V naphthenates, followed by steaming in the presence of air. While this method was easy to implement and did allow comparison of catalysts in the presence of metal contaminants, both the destruction of the zeolite and the metal dehydrogenation activity was greatly over-predicted (3, 4) in both MAT and riser testing. 

Coating or impregnation of catalyst materials on metal surfaces is expensive. 

The dry powder is sieved (50 - 200 pm), calcined at 500 C before the impregnation of catalyst species. 

Impregnation of Catalyst into Microreactor Pore Structures... 

The paper-impregnation drying oven exhausts contain high concentrations (10—20% LEL) of alcohols and some resin monomer. Vinyl resins and melamine resins, which sometimes also contain organic phosphate fire retardants, may be used for air filters. The organic phosphates could shorten catalyst life depending on the mechanism of reduction of catalyst activity. Mild acid leaching removes iron and phosphoms from partially deactivated catalyst and has restored activity in at least one known case. 

Distribution of Catalyst in Pores Because of the prac tical reqmrements of manufacturing, commercial impregnated catalysts usually have a higher concentration of ac tive ingredient near the outside than near the tip of the pores. This may not be harmful, because it seems that effectiveness sometimes is better with some kind of nonuni-form distribution of a given mass of catalyst. Such effects may be present in cases where the rate exhibits a maximum as a function of... 

A platinum on silica gel catalyst was prepared by impregnation of silica gel (BDH, for chromatographic adsorption) by a solution containing 0.5% (wt.) of sodium hydroxide and 0.5% (wt.) of chloroplatinic acid (both of analytical grade). The dried catalyst contained 1% (wt.) of platinum and a corresponding amount of the alkaline component. The BET surface area of the catalyst was 40 m2/g, the mean pore radius 150 A. The catalyst was always reduced directly in the reactor in a stream of hydrogen at 200°C for 2 hr. 

A silica-supported catalyst was prepared by anaerobic impregnation of Mo2Rh(/a-CO)(CO)4((7 -C,H,s),i (Fig. 70) from CHiCF solution, followed by evacuation at room temperature. Decomposition processes were observed at the... 

Bimetallic Co-Mo oxide specimens were prepared via co-impregnation of calculated amounts of cobalt nitrate and ammonia heptamolybdate on y-alumina to achieve a total metal loading of 20wt% with an equimolar Co Mo ratio. Nitridation of catalysts was carried in a fixed bed... 

The combustion temperature of soot particulates can be lowered by the addition of an oxidation catalyst in the form of fuel additives[2], by spraying metal salt solution on an accumulated soot or by the impregnation of filter walls with an oxidation catalyst. For the last option, oxides of supported metals are considered to be... 

Proven, industrially used catalysts are mostly based on either iron or cobalt. Ruthenium is an active F-T catalyst but is too expensive for industrial use. Both Fe and Co are prepared by several techniques including both precipitation and impregnation of (e.g. alumina or silica) supports. The more noble Ni catalyst produces nearly exclusively methane and is used for the removal of trace of CO in H2. 

---