CO HYDROGENATION OVER AL2O3 - PSEUDO-HYDROTHERMAL AND BASIC ALKALI-METAL COMPOUNDS PRETREATMENT EFFECT

Aluminas pretreated with pure water (pseudo-hydrothermal treatment) an d very dilute basic aqueous solutions were used as catalysts for CO hy drogenation. Pseudo-hydrothermal treatment results in an apparent enha ncement of ethylene selectivity at elevated temperature (> 673 K). The active sites seem to be coordinatively unsaturated metal and oxygen c ounterions (Lewis acid and base pair), which are very probably located on the most external surface of the alumina and can be coordinatively saturated by calcination in air. The precursors of the active sites p robably originate from a very thin layer of boehmite beyond XRD detect ing ability. They can be generated by both pseudo-hydrothermal treatme nt and dilute basic aqueous solution treatment of alumina.