Vapor phase catalysts splitting

Vapor-phase hydrogenation results and experimental evidence of this type lead to the conclusion that catalysts on basic supports are suitable for nonsplitting prehydrogenation-type reactions and that acidic supports are best used for splitting catalysts. Activated alumina was found to be the best support because of rapid reduction of tar acids. Especially, alumina precipitated from aluminum salts at constant pH was satisfactory and produced catalysts that could be formed into pellets of high mechanical strength. 

A number of vapor phase processes employing decarboxylating or carbon dioxide splitting catalysts have been proposed. In these processes the mixture of steam and phthalic anhydride vapor is circulated over the catalysts in a chamber maintained at temperatures varying from 300° to 450° C., depending on the active materials employed. 

Figure 16.23 shows the reactive distillation flowsheet for EtAc production. The reactive zone is placed in the lower section of the reactive distillation column. The condensed overhead vapor fiom the reactive distillation column is decanted. The aqueous product is withdrawn from the decanter and the organic phase is split, with a portion returned to the reactive distillation column and a portion fed to a stripping column that produces high purity EtAc. In the reactive distillation column, because the column base has much larger residence time than a tray, the catalyst holdup in the column base is assumed to be 10 times that on a reactive tray. The two fresh feeds into the reactive distillation are the alcohol feed below the azeotropic composition (87% EtOH and 13% H2O) and industrial grade acid feed (95 mol% HAc and 5% H2O). Following the work of Lai et al., the... 

---