Effect of Mg/Al Atomic Ratio of Mg-Al Hydrotalcites on Their Catalytic Properties for the Isomerization of Glucose to Fructose

Abstract

The effect of Mg/AI atomic ratio on the catalytic properties of Mg Al hydrotalcite was investigated. Mg Al hydrotalcites (Mg Al HT_X) with a wide range of Mg/AI atomic ratios (X = 0.5-3.5) were prepared via co-precipitation and applied to the isomerization of glucose to fructose. All characterizations performed in this study strongly support the successful formation of Mg Al HT_Xs with varying Mg/AI atomic ratios (X). It was revealed that Mg Al HT_Xs with lower Mg/AI atomic ratios retained smaller crystallite sizes and larger specific surface areas, resulting from the limitation of the growth of brucite-like layered structures by incorporated Al. This incorporation of Al into brucite-like layered structures enables Mg Al HT to retain abundant surface base sites, leading to enhanced catalytic activity. Fructose selectivity over Mg Al HT_Xs was analogous, whereas glucose conversion was different depending on the Mg/AI atomic ratio, Consequently glucose yield exhibited a volcano-shaped curve with respect to Mg/AI atomic, ratio (X), The Mg/AI atomic ratio of Mg Al HTs could play an important role in controlling their base properties and catalytic activities. Among the tested samples, Mg Al HT_1.5, with the smallest crystallite size and the largest specific surface area, exhibited the best catalytic performance attributed to its abundant surface base sites.