High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors

Abstract

We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m/Δm > 2500. The system design is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0–5000 amu in the current configuration). As a demonstration of the system performance we present data from ammonia oxidation on a Pt thin film showing resolved spectra of OH and NH3.

Engineering Ni–Mo–S Nanoparticles for Hydrodesulfurization

“…The small amount of catalytic nanoparticles necessitates the use of a very small reactor volume to detect the products of the catalytic reaction. We utilize a microreactor platform of our own design for this purpose. − The conditions (e.g., mass transport, pressure, temperature, etc.) in such a reactor are different from those in an industrial HDS reactor, and our experiments are, therefore, designed to show a general trend in the relation between structure and catalytic activity rather than comparisons with literature values.…”

“…The catalytic activity of the nanoparticles was assessed by the use of a microreactor platform that has been described in detail elsewhere. − In short, the reactor consisted of a microfabricated Si chip with a reactor volume of ∼250 nL connected to a time-of-flight mass spectrometer through a capillary outlet, allowing online monitoring of the gas composition in the reactor volume. Reactant gases were dosed through flow-controllers to two inlet channels, and the pressure in the reactor was controlled with a back-pressure controller.…”

Novel micro-reactor flow cell for investigation of model catalysts usingin situgrazing-incidence X-ray scattering

“…For a better temperature control and more homogeneous sample heating, we will replace the hotplate by platinum strips directly evaporated on the back of the reactor. In combination with a four-pin connection the platinum strip can be utilized for both sample heating and temperature monitoring by resistivity measurements (Andersen et al, 2012).…”

“…The temperature inside the reaction chamber for T < 523 K was therefore estimated from the parameters obtained from linear regression analysis of the apparent temperature measured with the thermocouple and the pyrometer. A more elaborate resistive sample heating and temperature determination from Pt strips evaporated on the Si side of the micro-reactor (Andersen et al, 2012) will be implemented in the near future. With the Pt strips we will achieve more precise temperature measurements and a better heat transfer, because of the direct contact with the Si part of the micro-reactor device.…”

“…A silicon/glass micro-reactor device, allowing the complete exchange of the reaction volume in a time on the order of seconds, was developed at DTU (Henriksen et al, 2009). This micro-reactor platform is frequently used in the Department of Physics at DTU to investigate chemical reactions over model (Andersen et al, 2012;Henriksen et al, 2009;Jensen et al, 2013) and photo-catalysts (Dionigi et al, 2012;Nielsen et al, 2012;In et al, 2011;Vesborg et al, 2010a).…”