Staining of fluid-catalytic-cracking catalysts: localising Brønsted acidity within a single catalyst particle.

A time-resolved in situ micro-spectroscopic approach has been used to investigate the Brønsted acidic properties of fluid-catalytic-cracking (FCC) catalysts at the single particle level by applying the acid-catalysed styrene oligomerisation probe reaction. The reactivity of individual FCC components (zeolite, clay, alumina and silica) was monitored by UV/Vis micro-spectroscopy and showed that only clay and zeolites (Y and ZSM-5) contain Brønsted acid sites that are strong enough to catalyse the conversion of 4-fluorostyrene into carbocationic species. By applying the same approach to complete FCC catalyst particles, it has been found that the fingerprint of the zeolitic UV/Vis spectra is clearly recognisable.

Catalytic activity in individual cracking catalyst particles imaged throughout different life stages by selective staining.

Fluid catalytic cracking (FCC) is the major conversion process used in oil refineries to produce valuable hydrocarbons from crude oil fractions. Because the demand for oil-based products is ever increasing, research has been ongoing to improve the performance of FCC catalyst particles, which are complex mixtures of zeolite and binder materials. Unfortunately, there is limited insight into the distribution and activity of individual zeolitic domains at different life stages.

Identification of active Zr-WO(x) clusters on a ZrO2 support for solid acid catalysts.

Tungstated zirconia is a robust solid acid catalyst for light alkane (C(4)-C(8)) isomerization. Several structural models for catalytically active sites have been proposed, but the topic remains controversial, partly because of the absence of direct structural imaging information on the various supported WO(x) species. High-angle annular dark-field imaging of WO(3)/ZrO(2) catalysts in an aberration-corrected analytical electron microscope allows, for the first time, direct imaging of the various species present.