Hybrid Catalysis (Netherlands)

The oxidative coupling of methane (OCM) was investigated using a catalyst with a core@shell structure or a physical mixture comprised of MgO and SiC or Fe3O4, which was thermally activated via conventional resistive heating or microwave heating.

A simple, modified Metal–Organic Chemical Deposition (MOCD) method for Pt, PtRu and PtCo nanoparticle deposition onto a variety of support materials, including C, SiC, B4C, LaB6, TiB2, TiN and a ceramic/carbon nanofiber, is described. Pt deposition using Pt(acac)2 as a precursor is shown to occur via a mixed solid/liquid/vapour precursor phase which results in a high Pt yield of 90–92% on the support material. Pt and Pt alloy nanoparticles range 1.5–6.2 nm, and are well dispersed on all support materials, in a one-step method, with a total catalyst preparation time of ∼10 hours (2.4–4× quicker than conventional methods). The MOCD preparation method includes moderate temperatures of 350 °C in a tubular furnace with an inert gas supply at 2 bar, a high pressure (2–4 bar) compared to typical MOCVD methods (∼0.02–10 mbar). Pt/C catalysts with Pt loadings of 20, 40 and 60 wt% were synthesised, physically characterised, electrochemically characterised and compared to commercial Pt/C catalysts. TEM, XRD and ex situ EXAFS show similar Pt particle sizes and Pt particle shape identifiers, namely the ratio of the third to first Pt coordination numbers modelled from ex situ EXAFS, between the MOCD prepared catalysts and commercial catalysts. Moreover, electrochemical characterisation of the Pt/C MOCD catalysts obtained ORR mass activities with a maximum of 428 A gPt−1 at 0.9 V, which has similar mass activities to the commercial catalysts (80–160% compared to the commercial Pt/C catalysts).

Voltage stability is a focal issue in every shipboard power system, where strict requirements (e.g. specified by STANAG 1008, classification rules, IEEE and IEC standards) are defined to guarantee safe operation under various operating conditions. This work proposes a low-voltage DC (LVDC) shipboard power system design and evaluates its voltage stability performance by comparing it with a standard low-voltage AC (LVAC) design. In order to evaluate the resulting transient performance, two different models are implemented with the aid of numerical simulation toolbox SimPowerSystems, working under the commercial software Matlab/Simulink. Voltage transients in LVAC and LVDC systems are simulated, resulting from an identical disturbance, i.e. disconnection of one of the Diesel Generators. From the observed transient responses, two different integral indices are used to assess the degree of system stability for both the LVAC and LVDC configurations. The indices considered are: Integral Absolute Error and Integral Time Absolute Error. The smaller values of the integral indices show the excellent capability of DC technology to maintain voltage stability following typical disturbances.