Hierarchically porous FER zeolite obtained via FAU transformation for fatty acid isomerization’

Skeletal isomerization of linear unsaturated fatty acids is important in the production of branched-chain saturated fatty acids with diverse applications. This reaction can be efficiently catalyzed by ferrierite (FER) zeolite. The reaction, however, suffers from diffusion limitations in the 10-membered ring channels. Herein, we report a method for the synthesis of hierarchically porous FER zeolite via transformation of FAU precursor driven by N-methylpyrrolidine (NMP) and amphiphile 1,2-dimethyl-3-hexadecyl-1H-imidazol-3-ium bromide (C16dMImz) as the structure-directing agent (SDA) and a mesoporogen, respectively, under hydrothermal conditions. This dual-template approach allows tuning the morphological and textural properties of the mesoporous FER materials by varying the concentration of the mesoporogen in the initial gel. The optimized FER sample is characterized by a high mesoporous volume (0.19 cm3 g-1), large external surface area (∼120 m2  g-1) and reduced crystal size in the a- and c-dimensions. This implies shortened diffusional pathways in the 10-membered ring channels. These modifications led to a significantly enhanced catalytic performance of hierarchical FER zeolite in the isomerization of fatty acids in comparison with a bulk FER reference zeolite

Hierarchically porous FER zeolite obtained via FAU transformation for fatty acid isomerization’

Skeletal isomerization of linear unsaturated fatty acids is important in the production of branched-chain saturated fatty acids with diverse applications. This reaction can be efficiently catalyzed by ferrierite (FER) zeolite. The reaction, however, suffers from diffusion limitations in the 10-membered ring channels. Herein, we report a method for the synthesis of hierarchically porous FER zeolite via transformation of FAU precursor driven by N-methylpyrrolidine (NMP) and amphiphile 1,2-dimethyl-3-hexadecyl-1H-imidazol-3-ium bromide (C16dMImz) as the structure-directing agent (SDA) and a mesoporogen, respectively, under hydrothermal conditions. This dual-template approach allows tuning the morphological and textural properties of the mesoporous FER materials by varying the concentration of the mesoporogen in the initial gel. The optimized FER sample is characterized by a high mesoporous volume (0.19 cm3 g-1), large external surface area (∼120 m2  g-1) and reduced crystal size in the a- and c-dimensions. This implies shortened diffusional pathways in the 10-membered ring channels. These modifications led to a significantly enhanced catalytic performance of hierarchical FER zeolite in the isomerization of fatty acids in comparison with a bulk FER reference zeolite

Skeletal isomerisation of oleic acid over ferrierite : Influence of acid site number, accessibility and strength on activity and selectivity

Protonated ferrierite shows superior activity and selectivity in the liquid-phase isomerisation of linear unsaturated fatty acids to (mono-)branched-chain unsaturated fatty acids, (Mo)BUFA. This high selectivity is remarkable, as most of the interior surface of the zeolite is blocked already at the onset of reaction, limiting reaction to the pore mouth. A detailed study of the relationship between ferrierite acidity and performance is reported for five commercial catalysts; significant differences were found, independently of their bulk Si/AI ratios. Initial pore conversion correlates with Bronsted acidity in the 10-MR channels, as determined by adsorption/desorption of pyridine and FTIR. A low density of external acid sites reduces oligomerisation of fatty acids, while a high ratio of Bronsted to Lewis sites explains the observed high BUFA yield. The combination of FTIR with CO adsorption, and temperature-programmed desorption of NH3, confirms that the presence of strong but few Bronsted acid sites in the 10-MR channels increases selectivity to MoBUFA. (C) 2015 Elsevier Inc. All rights reserved

Skeletal isomerisation of oleic acid over ferrierite in the presence and absence of triphenylphosphine : Pore mouth catalysis and related deactivation mechanisms

The formation and nature of coke (precursor) species has been studied during the skeletal isomerisation of oleic acid catalysed by protonated ferrierite, in the presence and absence of a triphenylphosphine promoter. UV-Vis and FT-IR spectroscopic analyses of the spent catalyst materials, complemented by NMR and mass spectrometry of the coke deposits extracted after HF dissolution, provide new insights into the deactivation mechanisms. Initial high catalyst activity and selectivity are quickly lost, despite conservation of the framework integrity, as a result of severe deactivation. Pore blockage is detected very early in the reaction, and only the pore mouth is actively employed. Additionally, polyenylic carbocations formed by hydrogen transfer reactions poison the active sites; they are considered to be the precursors to traces of condensed aromatics detected in the spent catalyst. Dodecyl benzene is the major "coke" constituent, and its precursor probably also competes for the active sites