MECHANISTIC ASPECTS OF THE HIGHER ALCOHOL SYNTHESIS OVER UNPROMOTED ZNCRO - 1-PROPANOL FLOW MICROREACTOR STUDY

Mechanistic aspects of the higher alcohol synthesis (HAS) over a ZnCrO sample are investigated by flow-microreactor experiments of 1-propano l. Results indicate that the catalyst can promote a number of chemical functions including hydrogenation/dehydrogenation, 'normal' and 'reve rsal' aldolic-type condensation, ketonization, alpha-addition, dehydra tion. On comparing the data with those obtained over a K-promoted samp le it appears that the alkali dopant does not affect the reactivity of ZnCrO towards hydrogenation/dehydrogenation and 'normal' aldolic-type condensation, is essential for 'reversal' aldolic-type condensation a nd alpha-addition, favors ketonization and essentially suppresses the dehydration function. Thus the alkali promoter, besides playing a cruc ial role in the C-1 --> C-2 step, significantly affects the chain grow th mechanisms involving C-2+ oxygenates and effectively preserves oxyg enate molecules towards the production of undesired hydrocarbons by de hydration.