Catalyst pretreatment

Then the standard emphasizes that all operations such as catalyst pretreatment and analytical techniques must be done as standardized to obtain meaningful relative results. 

As was found in Ref. [13], the method of catalytic decomposition of acetylene on graphite-supported catalysts provides the formation of very long (50 fim) tubes. We also observed the formation of filaments up to 60 fim length on Fe- and Co-graphite. In all cases these long tubules were rather thick. The thickness varied from 40 to 100 nm. Note that the dispersion of metal particles varied in the same range. Some metal aggregates of around 500 nm in diameter were also found after the procedure of catalyst pretreatment (Fig. 2). Only a very small amount of thin (20-40 nm diameter) tubules was observed. 

Fig. 3. compares the ammonia conversion for nanostructured vanadia/TiOa catalysts pretreated with O2 and 100 ppm O3/O2 gases. The reactions were conducted at 348 K for 3 h. No N2O and NO byproducts were detected in the reactor outlet. It is clear from the figure that higher vanadium content is beneficial to the reaction and ozone pretreatment yields a more active catalyst. Unlike the current catalysts, which require a reaction temperature of at least 473 K, the new catalyst is able to perform at much lower temperature. Also, unlike these catalysts, complete conversion to nitrogen was achieved with the new catalysts. Table 2 shows that the reaction rate of the new catalysts compared favorably with the established catalysts. 

Four mmoles of malononitrile and benzaldehyde were introduced in a batch stirred tank reactor at 323 K with toluene as solvent (30 ml). Then 0.05 g of aluminophosphate oxynitride was added. Samples were analysed by gas chromatography (Intersmat Delsi DI200) using a capillary column (CPSilSCB-25 m). Care was taken to avoid mass or heat transfer limitations. Before the reaction no specific catalyst pretreatment was done. 

The CO-reduced catalyst polymerizes ethylene much like its ethylene-reduced hexavalent parent and produces almost identical polymer [4]. Since the polymer properties are extremely sensitive to the catalyst pretreatment. 

Figure 4 Effect of repeated reaction cycles and catalyst pretreatment in 6.2 M NaOH at 473 K on rate constant and catalyst surface area for ethanolamine dehydrogenation over unpromoted skeletal copper under standard conditions.

Figure 1. DR UV-vis spectra of hydrated Fe-zeolite catalysts pretreated by calcination in flow of dry oxygen at 540 °C (black curves) and steam-treated in the flow of water vapor at 540 °C (gray curves). A) Fe-sil-12900, B) Fe-MTW-11500, C) Fe-MTW-14700, Fe-MTW-18900.

The bench-scale unit for the study of catalytic reactions has been designed with features such as accessibility, isothermal operation, and catalyst pretreatment. The use for catalytic screening tests makes easy accessibility a necessity, while the study of kinetics prescribes isothermal operation. 

Co/A1203 (Puralox) PFR 1. Positive transient 2. Weakly positive transient 50% syngas, = 13 bar, DCo = 4.9% 1. As prepared 2. Catalyst pretreated (deactivated) with steam... 

Selectivity of n-Hexane Transformations as a Function of Catalyst Pretreatment Temperature" (155d)... 

Figures 6 and 7 [72] show the CO conversion on different catalysts after catalyst pretreatment at 200 and 500°C, respectively. The intention of the catalytic experiments following catalyst pretreatment at 200°C is to see whether these catalysts are highly active...

Effect of Metal Oxide Additives on Au/Ti02, Catalyst Pretreated 200°C CaO, ZnO... 

Catalyst Pretreatment temp (K) Surface area (m /g) Reaction temp (K) Time (min) Conversion (%) E/ ratio... 

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