Catalyst performance testing

Figure 12.7-1. Schematic diagram of the reactor set-up for catalyst performance test.

The need for having good and realistic catalyst performance testing capabilities is obvious (1) For the catalyst producer, effective catalyst innovation is only possible if the many possible ideas and developments can be effectively checked. The costs of catalyst development are. Therefore a critical screening of the many leads generated is required. 

Large pilot plants remain indispensible only when in the development of an unconventional process sufficient amounts of novel product have to be made available for application studies, or when complex interactions between elements of the process have to be studied in an integrated way. In the latter case, a pilot plant will be a scaled-down version of an actual complex industrial plant, rather than just a reactor unit as required in catalyst performance testing or kinetic process studies. 

The catalyst performance tests were carried out in bench scale isothermal trickle-bed reactors. The reactor was loaded with 373 cm catalyst extrudates (0.13 cm diameter). The catalyst was diluted with 0.2-O.3 mm diameter (50-80 mesh) inert glass beads in order to improve the liquid distribution and contacting effidency witbin the reactor. 

Analyses of feed composition and of spent catalysts from the catalyst performance tests stxnv that there is a fwly good correlatioa between the amount of coke and the amount of PNA in the feeds as seen in figure 1. The amounts ci mono, di- or triarcnnatic compounds in the fised do not significantly influence the amount of coke. Since the sulfur compounds are almost exclusively found in the diaromatic fractions which often constitute the major part, the feed sulfur seems to be unimportant for coke formatioa These results show that the most important coke precursors must be present in the PNA fraction, which as mentioned also contains all the nitrogen compounds. 

Exelus has developed a novel structured catalytic system that allows one to meet all four criteria in a single catalytic system Hydrodynamic tests reveal that the HyperCat has similar gas hold-up as a slurry bubble column reactor but with a much lower liquid axial-dispersion coefficient. Cold-flow studies appear to indicate that the heat-transfer coefficient of this new system is similar to a bubble column reactor. Catalyst performance tests reveal that the performance of the HyperCat is similar to that of a powder catalyst when used in a plug-flow reactor. 

From this catalyst performance test the lifetime of SCR catalysts may be predicted, thus providing a replacement strategy for SCR elements. Honeycomb elements or plate-type elements are placed in the oven of a bench-scale setup. With this method the integral activity of an element is obtained. 

Figure 1. Catalyst Performance Test Results for Water Gas Shift Catalyst Materials...

Janssen, F. Meijer, R., "Quality control of DeNO catalysts Performance testing, surface analysis and characterization of DeNOx catalysts". Catalysis Today, 16,157 (1993). 

The coprecipitates were separated by filtration, air dried and calcined at 250 or 350° C In preparation for characterization and catalyst performance tests. The metal contents of the calcined coprecipitates were calculated from the residual metal contents of the equilibrium filtrates as determined by atomic absorption (Griswold and Fuss Environmental Laboratories, Manchester, CT). BET nitrogen surface areas were measured by Structure Probe, Fairfield, CT. Additional BET surfaces and CO chemisorption measurements were made by Porous Materials, Inc., Ithaca, NY. Xray diffraction analyses were made for selected samples to characterize the crystallinity of the calcined coprecipitates. 

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