Tunning catalytic acidity in Al2O3 nanofibers with mordenite nanocrystals for dehydration reactions

RODRIGUEZ-OLGUIN, M.A.; CRUZ-HERBERT, ROSA NERI; ATIA, H.; BOSCO M.,; FORNERO, ESTEBAN L.; ECKELT, R.; DE HARO DEL RÍO, DAVID; AGUIRRE, A.; GARDENIERS, J.G.E.; SUSARREY-ARCE, A.

Catalysis Science & Technology

Royal Society of Chemistry

Lugar: Zurich; Año: 2022

2044-4761

Alumina (Al2O3) is one of the most used supports in the chemical industry due to its exceptional thermal stability, surface area, and acidic properties. Mesoscopic structured alumina with adequate acidic is important in catalysis to enhance selectivity and conversion. This study introduces a synthetic method based on electrospinning to produce Al2O3 nanofibers (ANFs) with mordenite (MOR) nanocrystals (hereafter, hybrid ANFs) to tune the Lewis and Brønsted acid content. The hybrid ANFs with electrospinning form a non-woven network with macropores. ANF-HMOR, i.e. ANFs containing protonated mordenite (HMOR), shows the highest acidity of ca. 276 µmol/g as determined with infrared spectroscopy using pyridine as a molecular probe (IR-Py). IR-Py results reveal that Lewis acid sites are prominently present in the hybrid ANFs. Brønsted acid sites are also observed in the hybrid ANFs and are associated with MOR presence. The hybrid ANFs functionality is evaluated by performing methanol dehydration to dimethyl ether (DME). The proof of concept reaction reveals that ANF-HMOR is the more active and selective material with 87% conversion and 100% selectivity at 573 K compared to sodium ANFs with sodium exchanged MOR (ANF-NaMOR), ANFs, and the unstructured catalysts HMOR nanocrystals and Al2O3 counterparts. The results demonstrate that the acid site type and content can be modulated in hybrid ANF structures, end-synergistically improving selectivity and conversion during the methanol dehydration reaction. From a broader perspective, our results promote the utilization of hybrid structural materials as a means to tune chemical reactions selectively.