Modified Versions of AM‐4 for the Aqueous Phase Isomerization of Aldo‐Saccharides
Margarida M. Antunes, Auguste Fernandes, M.F. Ribeiro, Zhi Lin, Anabela A. Valente
Abstract
The isomerization of aldo‐saccharides to keto‐saccharides is an important transformation in biomass conversion processes. The use of eco‐friendly heterogeneous catalysts for these reactions is most attractive, albeit good catalytic stability continues a challenge. The as‐synthesized Aveiro‐Manchester material number 4 (AM‐4, Na 3 (Na,H)Ti 2 O 2 [Si 2 O 6 ] 2 ,2H 2 O) possessed isomerization activity, but limited stability. This versatile precursor material was modified to meet superior performances in the base‐catalyzed isomerization of the monosaccharides d ‐glucose and d ‐xylose, and the disaccharide d ‐cellobiose, at 100 °C. Different alkali and alkaline‐earth metals were introduced into AM‐4, which influenced the catalytic properties. The Mg‐containing material was the most stable, leading to 27 % fructose yield from d ‐glucose, 41 % cellobiulose from d ‐cellobiose and 39 % xylulose from d ‐xylose isomerization, at 2 h reaction.