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.

Monitoring transport phenomena of paramagnetic metal-ion complexes inside catalyst bodies with magnetic resonance imaging.

An indirect magnetic resonance imaging (MRI) method has been developed to determine in a noninvasive manner the distribution of paramagnetic Co2+ complexes inside Co/Al2O3 catalyst extrudates after impregnation with Co2+/citrate solutions of different pH and citrate concentrations. UV/Vis/NIR microspectroscopic measurements were carried out simultaneously to obtain complementary information on the nature of the Co2+ complexes. In this way, it could be confirmed that the actual distribution of Co2+ inside the extrudates could be derived from the MRI images.

Insights into the preparation of supported catalysts: a spatially resolved Raman and UV-Vis spectroscopic study into the drying process of CoMo/gamma-Al2O3 catalyst bodies.

Spatially resolved Raman and UV-vis-NIR microspectroscopy have been used as tools to study the preparation process of supported catalyst bodies. Detailed spectroscopic information on the local coordination geometry of two different metallic species along with their macro-distribution over the catalyst body has been obtained, enabling a good understanding of the physicochemical processes occurring during the drying process of impregnated gamma-Al(2)O(3) bodies. The formation and decomposition of the Keggin-type complex H(x)PMo(11)CoO(40)((7-)(x)-), which is considered to be a potential precursor for CoMoS(2)/gamma-Al(2)O(3) HDS catalysts, inside gamma-Al(2)O(3) bodies is shown to be a function of the composition of the impregnation solutions, the aging time, and the drying conditions applied.

Noninvasive in situ visualization of supported catalyst preparations using multinuclear magnetic resonance imaging.

Multinuclear magnetic resonance imaging (MRI) is employed as a new noninvasive tool for monitoring supported catalyst preparation by visualizing precursor transport within the porous support. In particular, liquid phase 31P MRI experiments were used to visualize the dynamics of H3PO4 penetration into an alumina pellet and have revealed a strong interaction of H3PO4 with the support. Solid state 31P MRI was applied to map the distribution of the adsorbed phosphate inside the support after its drying.

Spatially resolved Raman and UV-visible-NIR spectroscopy on the preparation of supported catalyst bodies: controlling the formation of H2PMo11CoO40 5- inside Al2O3 pellets during impregnation.

The physicochemical processes that occur during the preparation of CoMo-Al2O3 hydrodesulfurization catalyst bodies have been investigated. To this end, the distribution of Mo and Co complexes, after impregnation of gamma-Al2O3 pellets with different CoMoP solutions (i.e.

UV-Vis microspectroscopy: probing the initial stages of supported metal oxide catalyst preparation.

A UV-vis microspectroscopy methodology for monitoring the speciation and macrodistribution of catalyst-precursor species inside catalyst-support bodies at the initial stages of catalyst preparation has been developed. The setup is based upon optical-fiber technology and allows spatially resolved analysis of bisected catalyst bodies. The potential of this tool is demonstrated by two pore-volume impregnation studies involving Ni2+ d-d transition bands and Cr6+ charge-transfer bands.

Envisaging the physicochemical processes during the preparation of supported catalysts: Raman microscopy on the impregnation of Mo onto Al2O3 extrudates.

Raman microscopy has been applied to study the preparation of shaped Mo/Al(2)O(3) catalysts. The speciation of different Mo complexes over gamma-Al(2)O(3) support bodies was followed in time after pore volume impregnation with aqueous solutions containing different Mo complexes. The addition of NO(3-) to the impregnation solutions allows for a quantitative Raman analysis of the distribution of different complexes over the catalyst bodies as this ion can be used as an internal standard.