γ-Stearolactone ring-opening by zeolites for the production of branched saturated fatty acids.

C branched saturated fatty acids (BSFA) are used as ingredients in cosmetics and lubricants and are produced the hydrogenation of C branched unsaturated fatty acids (BUFA). Industrial-grade C BUFA contain the odorous by-product γ-stearolactone (GSL), which must be removed by acid-catalysed ring-opening of GSL into oleic acid. Zeolites such as Y and beta can facilitate the ring-opening, but due to the dimensions of GSL the activity is expected to be limited by diffusion into the micropores.

time-gated Raman spectroscopy of solid catalysts.

Raman spectroscopy is a powerful analytical tool to provide new insights in the working and deactivation principles of solid catalysts. Intense fluorescence can obscure Raman spectra to the extent that they become uninterpretable. Time-gated Raman spectroscopy, based on pulsed excitation and time-gated detection, suppresses background fluorescence based on its slower time dynamics compared to Raman scattering.

Probing coke formation during the methanol-to-hydrocarbon reaction on zeolite ZSM-5 catalyst at the nanoscale using tip-enhanced fluorescence microscopy.

The deactivation mechanism of the widely used zeolite ZSM-5 catalysts remains unclear to date due to the lack of analytical techniques with sufficient sensitivity and/or spatial resolution. Herein, a combination of hyperspectral confocal fluorescence microscopy (CFM) and tip-enhanced fluorescence (TEFL) microscopy is used to study the formation of different coke (precursor) species involved in the deactivation of zeolite ZSM-5 during the methanol-to-hydrocarbon (MTH) reaction. CFM submicron-scale imaging shows a preferential formation of graphite-like coke species at the edges of zeolite ZSM-5 crystals within 10 min of the MTH reaction (, working catalyst), whilst the amount of graphite-like coke species uniformly increased over the entire zeolite ZSM-5 surface after 90 min (, deactivated catalyst).

New insights into the NH-selective catalytic reduction of NO over Cu-ZSM-5 as revealed by spectroscopy.

To control diesel vehicle NO emissions, Cu-exchanged zeolites have been applied in the selective catalytic reduction (SCR) of NO using NH as reductant. However, the harsh hydrothermal environment of tailpipe conditions causes irreversible catalyst deactivation. The aggregation of isolated Cu brings about unselective ammonia oxidation along with the main NH-SCR reaction.

Visualizing defects and pore connectivity within metal-organic frameworks by X-ray transmission tomography.

Metal-Organic Frameworks (MOFs) have the potential to change the landscape of molecular separations in chemical processes owing to their ability of selectively binding molecules. Their molecular sorting properties generally rely on the micro- and meso-pore structure, as well as on the presence of coordinatively unsaturated sites that interact with the different chemical species present in the feed. In this work, we show a first-of-its-kind tomographic imaging of the crystal morphology of a metal-organic framework by means of transmission X-ray microscopy (TXM), including a detailed data reconstruction and processing approach.