Brønsted acid sites based on penta-coordinated aluminum species

• DOI: 10.1038/ncomms13820
• Publication Date: 2016-12-15T13:25:32Z
• Authors: Zichun Wang; Yijiao Jiang; Olivier Lafon; Julien Trébosc; Kyung Duk Kim; Catherine Stampfl; Alfons Baiker; Jean-Paul Amoureux; Jun Huang
• Keywords: Magic angle spinning; Solid acid

Abstract Zeolites and amorphous silica-alumina (ASA), which both provide Brønsted acid sites (BASs), are the most extensively used solid catalysts in chemical industry. It is widely believed that BASs consist only of tetra-coordinated aluminum (Al IV ) with bridging OH groups zeolites or nearby silanols on ASA surfaces. Here we report direct observation a new type BAS based penta-coordinated species V by 27 Al-{ 1 H} dipolar-mediated correlation two-dimensional NMR experiments at high magnetic field under magic-angle spinning. Both BAS-Al -Al show similar acidity to protonate probe molecular ammonia. The quantitative evaluation H Al demonstrates co-exists rather than replaces it, opens avenues for strongly enhancing these popular acids.