(235c) Synthesis and Characterization of Maleic Acid – Aluminum Catalyst for Glucose Conversion

Authors: 
Zhang, X., Purdue University
Mosier, N. S., Purdue University
Maleic acid (MA) and AlCl3 self-assemble into catalytic complexes (Al-(MA)2-(OH)2(aq)) with improved selectivity for converting glucose to value-added chemicals in water. Use of maleic acid and AlCl3 compared to HCl and AlCl3 shows an increase in selectivity (2.6 to 11) of fructose conversion to hydroxymethylfurfural at 180°C. We report the production of Al-(MA)2-(OH)2(aq) formed by reaction of maleic acid and AlCl3 and confirmed by high pressure liquid chromatography (HPLC) and mass spectrometry. Reaction of 100 mM maleic acid and 100 mM AlCl3 at 100°C for 24 hours shows a modest 25.9% production of Al-(MA)2-(OH)2(aq) with some degradation of maleic acid to malic acid. Increasing beginning concentrations to 500 mM maleic acid and 500 mM AlCl3 shows an increase in selectivity (0.34 to 0.47) for Al-(MA)2-(OH)2(aq) over malic acid production. Storage of the refluxed liquid at 4°C yields formation of precipitate crystals containing 92.6% catalyst complex. Alteration of initial reflux concentrations to 500 mM maleic acid and 250 mM AlCl3 shows an increase in Al-(MA)2-(OH)2(aq) production and purity (18.2% to 20.2%) in Al-(MA)2-(OH)2(aq) present in solution. Forming crystals by precipitation shows a change in morphology of formed crystals and an increase in purity to 94.6% compared to the equal molar reflux liquid. Rinsing crystals with deionized water removes residual maleic acid and malic acid yielding crystals with 99.2% purity catalyst complex. Future work will include a study on x-ray crystallography and a study on complex catalytic conversion of glucose including kinetics and conversion yield.