Photo-spectroscopy of mixtures of catalyst particles reveals their age and type

Abstract

Within a fluid catalytic cracking (FCC) unit, a mixture of catalyst particles that consist of either zeolite Y (FCC-Y) or ZSM-5 (FCC-ZSM-5) is used in order to boost the propylene yield when processing crude oil fractions. Mixtures of differently aged FCC-Y and FCC-ZSM-5 particles circulating in the FCC unit, the so-called equilibrium catalyst (Ecat), are routinely studied to monitor the overall efficiency of the FCC process. In this study, the age of individual catalyst particles is evaluated based upon photographs after selective staining with substituted styrene molecules. The observed color changes are linked to physical properties, such as the micropore volume and catalytic cracking activity data. Furthermore, it has been possible to determine the relative amount of FCC-Y and FCC-ZSM-5 in an artificial series of physical mixtures as well as in an Ecat sample with unknown composition. As a result, a new practical tool is introduced in the field of zeolite catalysis to evaluate FCC catalyst performances on the basis of photo-spectroscopic measurements with an off-the-shelf digital single lens reflex (DSLR) photo-camera with a macro lens. The results also demonstrate that there is an interesting time and cost trade-off between single catalyst particle studies, as performed with e.g. UV-vis, synchrotron-based IR and fluorescence micro-spectroscopy, and many catalyst particle photo-spectroscopy studies, making use of a relatively simple DSLR photo-camera. The latter approach offers clear prospects for the quality control of e.g. FCC catalyst manufacturing plants.

Magnetophoretic Sorting of Single Catalyst Particles

“…This industrial approach consisted of a permanent rolling magnet cylinder under a belt where particles with different sizes were fed on, to sort them in just two fractions. [40] In this work, however, the particles have been pre-sorted by size and we focus on the relation of Fe content, magnetic properties and the availability of Brønsted acid sites [41][42][43][44] in a wide range of Fe content and on real, industrially processed ECAT particles, providing a unique catalyst diagnostics platform for single particle analysis.…”

“…Previous work demonstrated that the Brønsted acid-catalysed oligomerization of 4-methoxystyrene visualizes zeolite domains by fluorescence micro-spectroscopy. [43,44,48] This fluorescence was used as a measure for acidity by averaging the fluorescence intensity per particle over AE 100 ECAT particles for all five fractions.…”

Concluding remarks: progress toward the design of solid catalysts

“…Imaging methods, some of them quite novel in catalysis research, 7,8 were also used widely in the work reported at the Faraday Discussion, and these included characterization of zeolitecontaining cracking catalysts investigated on the scale of microns. Important components of industrial catalysts for hydrocarbon cracking in the manufacture of petrol incorporate binders and amorphous components in addition to zeolite crystallites, and results presented at the Faraday Discussion demonstrate their high degrees heterogeneity-on the scale of micronsperhaps a surprising result in view of the enormous scale of application of cracking catalysts.…”

Single Catalyst Particle Diagnostics

“…This industrial approach consisted of a permanent rolling magnet cylinder under a belt where particles with different sizes were fed on, to sort them in just two fractions. 42 In this work, however, the particles have been pre-sorted by size and we focus on the relation of Fe content, magnetic properties and the availability of acid sites [43][44][45][46] in a wide range of Fe content and on real, industrially processed FCC ECAT particles, providing a unique catalyst diagnostics platform for single particle analysis.…”

“…The oligomerization of 4-methoxystyrene is catalysed by the Brønsted acid sites in zeolite domains and induces fluorescence. 40,45,46 This fluorescence was used as a measure for acidity by averaging the fluorescence intensity per particle over ± 100 catalyst particles for all five fractions. These average intensities were compared with Nile blue A staining results.…”