Guerbet Reaction over Strontium-Substituted Hydroxyapatite Catalysts Prepared at Various (Ca+Sr)/P Ratios.

The Guerbet reaction of ethanol to heavier products was performed over a series of extensively characterized Sr-substituted hydroxyapatites (HAPs) with different (Ca+Sr)/P ratios, and thus different structural, textural, and acid-base properties. The acid-base properties were correlated with the reactivity of the solids and an optimal ratio between the amount of acid and basic sites was determined (ca. 4), whereas the ethanol conversion was mainly depending on the specific surface area of the solids. The stoichiometric 100 mol % Sr-substituted sample (SrAp-100) was especially efficient in higher alcohols production, which can be illustrated by a total alcohol selectivity (76.4 %) higher than that of all the other solids at a 13 % ethanol isoconversion. [ABSTRACT FROM AUTHOR]