On the Use of Silicon Nitride in Catalysis

Abstract

Aires, F. J. Cadete Santos Bertolini, J. C.Silicon nitride has very good thermal and chemical stability, as well as high thermal conductivity compared to oxide materials, which are commonly used as catalyst supports. In exothermic reactions working at high temperature, this facilitates heat transfer and thus limits the formation of local hot spots, which are often responsible for structural modification of the support in addition to sintering of active phases. However, it is only recently that this material has been considered for application as a catalyst support for high temperature reactions. It is now established that silicon nitride can be a good support for catalytically active phases. Its range of application is continually expanding (e.g., partial/total oxidation of methane, hydrogenation and dehydrogenation reactions, photocatalysis, base catalysis, etc.)

Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?

“…It is worth mentioning that in our own work SiN x has been observed to crystallize in situ when temperatures above 800 °C are used under an oxygen-containing atmosphere. (ii) Silicon nitrides are chemically relatively inert, heat resistant and heat conductive [58,158]. It should be noted that SiN x windows can in fact corrode under specific conditions [159,160], which has to be taken into account for the planning of in situ experiments.…”

“…SiN x windows often act as catalyst supports, as catalyst particles can be directly prepared on their surface [23,24,105]. The catalytic properties of deposited materials are affected through support interactions [158]. Thus, an inhomogeneous SiN x surface could play a role in the uneven behavior of NPs under reaction conditions as seen for instance, in operando investigations of the morphological evolution of Pt NPs [24].…”

“…Studies of SiN x as a catalyst support have shown that amorphous SiN x supports are detrimental to the catalytic performance of Pt catalysts for the partial oxidation of methane, as it forms a SiO 2 overlayer on the Pt NPs [163]. Moreover, Pt/a-SiN x catalysts have shown catalytic activity superior to Pt/MgO reference systems for propane dehydrogenation which was attributed to the basic nature of SiN x [158]. Hullman et al [164] showed that carbon, boron or titanium doping of the SiN x support can significantly influence its catalytic properties.…”

“…Silicon atoms can be more easily oxidized in such silicon-rich compositions and a case can be made for a likely oxygen or OH termination on the surface of the windows. Santos Aires et al [158] performed X-ray photoelectron spectroscopy (XPS) measurements on amorphous SiN x particles and found significant amounts of surface oxygen. Zaluzec et al detected small amounts of both O and Cl incorporated into SiN x films deposited by LPCVD [167].…”

Synthesis and methane cracking activity of a silicon nitride supported vanadium nitride nanoparticle composite

“…2 Silicon nitride is also of interest as a catalyst support due to the high thermal conductivity relative to the more commonly used silicas, and in the α-Si 3 N 4 form is oxidation resistant at typical catalytic process temperatures. 3,4 Gel-based routes to silicon nitrides and imidonitrides utilise solutionphase reactions of precursor molecules, usually amides, with cross-linking groups such as ammonia 5 or isocyanate. 6 These make polymeric species in solution, and when the polymeric material immobilises the liquid phase, the latter can be removed to provide high surface area materials that often contain basic surface groups.…”