Evolution of a Metal‐Organic Framework into a Brønsted Acid Catalyst for Glycerol Dehydration to Acrolein

Metal−organic frameworks (MOFs) as solid acid catalysts provide active sites with definite structures. Here, Zr6‐based MOF‐808 and its derivatives were studied as catalysts for glycerol dehydration, the products of which (acrolein vs. acetol) are very sensitive to the nature of the catalytic acid sites. Evolving MOF‐808 into MOF‐808‐S with a 120 % increase in the number of Brønsted OH−/H2O coordinated to ZrIV and a vanished Lewis acidity by steam treatment, the post‐synthetically modified catalyst presented 100 % conversion of glycerol, 91 % selectivity to acrolein, and 0 % selectivity to acetol within the active window. Real‐time analysis of the product composition indicated the in situ MOF structural evolution. Overall, the specific MOF‐substrate interaction characterized by the probe reaction provides more understandings on the structural evolution of the MOFs and their impact on the performance as solid acid catalysts. Full steam ahead: By steam treatment, MOF‐808 with weak Lewis/Brønsted acidity is transformed to MOF‐808‐S featuring more strong sites with exclusive Brønsted acidity. The structural evolution leads to high selectivity to acrolein in glycerol dehydration.