MEMS Nanoreactors

MEMS Nanoreactors

In Situ X-ray Microscopy Reveals Particle Dynamics in a NiCo Dry Methane Reforming Catalyst under Operating Conditions

Herein, we report the synthesis of a γ-Al2O3-supported NiCo catalyst for dry methane reforming (DMR) and study the catalyst using in situ scanning transmission X-ray microscopy (STXM) during the reduction (activation step) and under reaction conditions. During the reduction process, the NiCo alloy particles undergo elemental segregation with Co migrating toward the center of the catalyst particles and Ni migrating to the outer surfaces. Under DMR conditions, the segregated structure is maintained, thus hinting at the importance of this structure to optimal catalytic functions. Finally, the formation of Ni-rich branches on the surface of the particles is observed during DMR, suggesting that the loss of Ni from the outer shell may play a role in the reduced stability and hence catalyst deactivation. These findings provide insights into the morphological and electronic structural changes that occur in a NiCo-based catalyst during DMR. Further, this study emphasizes the need to study catalysts under operating conditions in order to elucidate material dynamics during the reaction.

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MEMS Nanoreactors

Capturing the Genesis of an Active Fischer–Tropsch Synthesis Catalyst with Operando X‐ray Nanospectroscopy

A state‐of‐the‐art operando spectroscopic technique is applied to Co/TiO2 catalysts, which account for nearly half of the world’s transportation fuels produced by Fischer–Tropsch catalysis. This allows determination of, at a spatial resolution of approximately 50 nm, the interdependence of formed hydrocarbon species in the inorganic catalyst. Observed trends show intra‐ and interparticular heterogeneities previously believed not to occur in particles under 200 μm. These heterogeneities are strongly dependent on changes in H2/CO ratio, but also on changes thereby induced on the Co and

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MEMS Nanoreactors

Visualization of oscillatory behaviour of Pt nanoparticles catalysing CO oxidation

Many catalytic reactions under fixed conditions exhibit oscillatory behaviour. The oscillations are often attributed to dynamic changes in the catalyst surface. So far, however, such relationships were difficult to determine for catalysts consisting of supported nanoparticles. Here, we employ a nanoreactor to study the oscillatory CO oxidation catalysed by Pt nanoparticles using time-resolved high-resolution transmission electron microscopy, mass spectrometry and calorimetry. The observations reveal that periodic changes in the CO oxidation are synchronous with a periodic refacetting of the Pt

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MEMS Nanoreactors

An all-in-one nanoreactor for high-resolution microscopy on nanomaterials at high pressures

We present a new MEMS nanoreactor fully integrated on a single die. It enables atomic-scale imaging of nanostructured materials under the high pressures and temperatures that are typical for many industrial applications (14 bar and 660°C). The reactor can therefore be used to study the behavior of e.g. catalysts in a transmission electron microscope (TEM). It has a shallow channel (0.5 μm), which is made with surface micromachining techniques and contains pillars that prevent bulging. Integrated with the channel are

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MEMS Optomechanical Oscillators

Other MEMS devices