Large Ferrierite Crystals as Models for Catalyst Deactivation during Skeletal Isomerisation of Oleic Acid: Evidence for Pore Mouth Catalysis. Issue 1 (27th November 2015)

• Record Type: Journal Article
• Authors: Wiedemann, Sophie C. C.; Ristanović, Zoran; Whiting, Gareth T.; Reddy Marthala, V. R.; Kärger, Jörg; Weitkamp, Jens; Wels, Bas; Bruijnincx, Pieter C. A.; Weckhuysen, Bert M.
• Is Part Of: Chemistry. Volume 22:Issue 1(2016)
• Page Start: 199
• Page End: 210
• Publication Date: 2015-11-27
• Subjects: ferrierite -- isomerisation -- micro‐spectroscopy -- pore mouth catalysis -- zeolites; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201503551
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Large zeolite crystals of ferrierite have been used to study the deactivation, at the single particle level, of the alkyl isomerisation catalysis of oleic acid and elaidic acid by a combination of visible micro‐spectroscopy and fluorescence microscopy (both polarised wide‐field and confocal modes). The large crystals did show the desired activity, albeit only traces of the isomerisation product were obtained and low conversions were achieved compared to commercial ferrierite powders. This limited activity is in line with their lower external non‐basal surface area, supporting the hypothesis of pore mouth catalysis. Further evidence for the latter comes from visible micro‐spectroscopy, which shows that the accumulation of aromatic species is limited to the crystal edges, while fluorescence microscopy strongly suggests the presence of polyenylic carbocations. Light polarisation associated with the spatial resolution of fluorescence microscopy reveals that these carbonaceous deposits are aligned only in the larger 10‐MR channels of ferrierite at all crystal edges. The reaction is hence further limited to these specific pore mouths. Abstract : Catalysis at the edge : Large zeolite crystals of ferrierite have been used to study catalyst deactivation in the alkyl isomerisation of oleic and elaidic acid by a combination of micro‐spectroscopy methods (see figure). It was found that the markers of catalytic activity were exclusively found near the pore mouths of the larger 10‐MR channels of ferrierite at all crystal edges, providing experimental evidence for the concept of pore mouth catalysis.