RESUMO
Unveiling the coke formation in zeolites is an essential prerequisite for tackling the deactivation of these catalysts in the transformations of hydrocarbons. Herein, we present the direct mapping of coke in the micropores of ZSM-5 catalysts used in methanol-to-hydrocarbons conversion by single-crystal electron diffraction analysis. The latter technique revealed a polycyclic aromatic structure along the straight channel, wherein the high-quality data permit refinement of its occupancy to about 40 %. These findings were exploited to analyze the evolution of micropore coke during the reaction. Herein, coke-associated signals, which correlate with the activity loss, indicate that the nucleation of coke commences in the intersections of sinusoidal and straight channels, while the formation of coke in the straight pores occurs in the late stages of deactivation. The findings uncover an attractive method for analyzing coke deposition in the micropore domain.
RESUMO
This protocol describes the production and operation of a microfluidic dissection platform for long-term, high-resolution imaging of budding yeast cells. At the core of this platform is an array of micropads that trap yeast cells in a single focal plane. Newly formed daughter cells are subsequently washed away by a continuous flow of fresh culture medium. In a typical experiment, 50-100 cells can be tracked during their entire replicative lifespan. Apart from aging-related research, the microfluidic platform can also be a valuable tool for other studies requiring the monitoring of single cells over time. Here we provide step-by-step instructions on how to fabricate the silicon wafer mold, how to produce and operate the microfluidic device and how to analyze the obtained data. Production of the microfluidic dissection platform and setting up an aging experiment takes ~7 h.
