Deactivation of Zeolite Catalyst H-ZSM-5 during Conversion of Methanol to Gasoline: Operando Time- and Space-Resolved X-ray Diffraction

Abstract

The deactivation of zeolite catalyst H-ZSM-5 by coking during the conversion of methanol to hydrocarbons was monitored by high-energy space- and time-resolved operando X-ray diffraction (XRD) . Space resolution was achieved by continuous scanning along the axial length of a capillary fixed bed reactor with a time resolution of 10 s per scan. Using real structural parameters obtained from XRD, we can track the development of coke at different points in the reactor and link this to a kinetic model to correlate catalyst deactivation with structural changes occurring in the material. The "burning cigar" model of catalyst bed deactivation is directly observed in real time.

Catalytic conversion of furanic compounds over Ga-modified ZSM-5 zeolites as a route to biomass-derived aromatics

“…Therefore, the amount of active catalyst decreases as function of time on stream. 38,39 The reaction profiles shown in Figure S4 show that the concentration of olefins (ethylene and propylene) increased during deactivation (and therefore with contact time). This implies that olefinic compounds formed during earlier reaction stages are converted to aromatics in the presence of Ga species.…”

Hierarchical H-ZSM5 zeolites based on natural kaolinite as a high-performance catalyst for methanol to aromatic hydrocarbons conversion

“…MTH products are essential raw materials for downstream petrochemical industries such as oil and polymers 8,9 . A current problem in MTH process with conventional ZSM-5 catalyst is the fast deactivation of ZSM-5 due to the rapid coke deposition on Bronsted acidic sites and diffusion limitation in the microporous structure of ZSM-5 10 . In this regard, designing zeolites with pores larger than micropores and reducing crystal size in order to shorten the diffusion length could be good strategies to developing more efficient catalysts.…”

Topology-dependent hydrocarbon transformations in the methanol-to-hydrocarbons reaction studied by operando UV-Raman spectroscopy

“…When ZSM-5 is used in MTH in a fixed-bed reactor, it is well established that deactivation occurs first at the top layers and then progressively proceeds toward the bottom. 7,[39][40][41] This behaviour, has also been described as a "burning cigar" type of evolution, and therefore the data will strongly depend on the sampling point, i.e. the laser focal point.…”