Catalyst preparation extrusion

From the results obtained in this study [205], it was concluded that the catalyst prepared by extrusion of a paste containing the TiOz precursor together with natural silicates, is more active in the photocatalytic mineralization of organic compounds than the coated film. 

Mode of preparation Differences can be expected between catalysts prepared by simple impregnation using incipient wetness, impregnation by immersion in a solution of the components, coprecipitation, kneading, or mixed-mull extrusion. The order of addition of Co and Mo when calcination is made between impregnations can also affect the outcome. 

Isopova ct al. described the preparation of various perovskite-based monolithic catalysts for fuel combustion by extrusion of synthesized perovskite powders [14]. Blanco ct al. [25], Lachman and Williams [97], and del Valle et al. [98] reported titania-based and other monolithic catalysts by extrusion. The titania catalysts were tested in a coal-fired power pilot plant for electrostatic separation of fly-ash [98]. Lyakhova et al. studied the W03-doped titania-vanadia monolithic catalysis for selective catalytic reduction (SCR NOx conversion) by extrusion [26]. The rheological properties of the paste for extrusion and the effect of various organic plastisizers on catalytic activity in SCR were discussed. 

Polymers with broad MWD, suitable for application fields such as blow molding and extrusion, are obtained with catalysts prepared after proper choiche of ... 

Fig. 4. Configuration of a ceramic membrane reactor for partial oxidation of methane. The membrane tube, with an outside diameter of about 6.5 mm and a length of up to about 30 cm and a wall thickness of 0.25-1.20 mm, was prepared from an electronic/ionic conductor powder (Sr-Fe-Co-O) by a plastic extrusion technique. The quartz reactor supports the ceramic membrane tube through hot Pyrex seals. A Rh-containing reforming catalyst was located adjacent to the tube (57).

The PU compositions can be prepared by dispersing the mass ABS resin in the reactants used to prepare the PU and then contacting the resultant dispersion with the other urethane reactants under conditions sufficient to form the PU. The reaction can be accelerated by the addition of suitable urethane catalysts, for example by tertiary amines (33). When the PU is prepared by reactive extrusion, the ABS resin may be added already initially along with the urethane-forming reactants. This toughened PU is particularly useful in making structural automotive body parts and housings for electrical appliances. 

Further details have been presented of the one-step preparation of vitamin K analogues through the use of -cyclodextrin extrusion catalysts. A paper has appeared dealing with the photoreduction of vitamin K [phylloquinone (229)]. ... 

Pyrazolines can also be prepared by the oxidation of pyrazolidines. 2-Pyrazolines, which are readily obtained in the reaction of a,j -unsaturated ketones with hydrazine, also undergo nitrogen extrusion at elevated temperature usually in the presence of a basic catalyst. The reaction is believed to proceed via 1-pyrazolines. Treatment of 3,3,5-trialkyl-2-pyrazolines with lead tetraacetate followed by thermolysis affords cyclopropyl acetates ". Oxidation of certain 2-pyrazolines with manganese dioxide gives 3H-pyrazoles, which in turn produce cyclopropenes in the photolysis (equation 7). ... 

A template is described as temporary or external if it is eliminated like a homogeneous catalyst at the end of a synthesis and is therefore not incorporated into the end product [27]. Sulfur or nitrogen, which can be eliminated by pyrolysis from the product after a successful reaction, can be regarded as the best-known exo templates. For example, McMurry et al. [28] used extrusion of Na and S (Barton method) from the thiadiazolines 25 in the preparation of the 16-membered hydrocarbon macrocycle 26 (Scheme 7). 

Tandem sequences have also yielded some interesting pyrazole structures. Four-component coupling of terminal alkynes 37, hydrazines 38, carbon monoxide and aryl iodides furnished pyrazoles 39 in the presence of palladium catalyst <05OL4487>. Fully substituted 1/f-pyrazoles 42 were prepared from the condensation/fragmentation/cyclization/extrusion reactions of thietanone 40 with 1,2,4,5-tetrazines 41 <05JOC8468>. Reactions of isocyanides 43 and dialkyl acetylenedicarboxylates 44 in the presence of 1,2-diacylhydrazines 45 led to highly-functionalized pyrazolines 46 <05TL6545>. 

Gamma alumina extrusions (3 mm dia 10 mm length) were used as the support. Its BET surface area is 240 m /g and pore volume is 0.65 cc/g. All the catalysts were prepared by impregnating AI2O3 extrusions with H2PtCl6 solution. Wet impregnated extrusions were further processed to four different types of catalysts as follows ... 

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