Effect of preparation method on the structure and catalytic property of activated carbon supported nickel oxide catalysts

A series of activated carbon (AC) supported nickel oxide (NiO) catalysts were prepared by aqueous reduction preparation methods with nickel nitrate as a precursor. The effects of preparation procedure and reducing agent on catalyst structure and catalytic property were investigated. Based on the information obtained from physico-chemical characterizations and sorbitol dehydration performances, preparation methods were found to have a significant influence on NiO distribution and surface acidity. The catalysts prepared through the simultaneous loading-reduction procedure had stronger acidity and higher NiO dispersion on the outer surface of AC, which contributed jointly to high sorbitol conversion (turn-over frequency of 190-240 h^-1) and slightly low selectivity to anhydro sugar alcohols (ca. 66%). Correspondingly, with the procedure of reduction of supported nickel catalyst precursors, the selectivity to anhydro sugar alcohols was improved by ca. 10%, while sorbitol conversion was quite low (ca. 20%). Reducing agent exerted less influence on the structure compared with preparation procedure. However, when the simultaneous loading-reduction procedure was used, sodium borohydride influenced the acidity remarkably by formation of a new strong acid site, resulting in better dehydration performances.