Carsten Pätzold

Methanol Utilisation Technologies

Oil and gas are raw materials—the availability of which is prognosticated to run short in the near future. The peak oil discussion is an example generally perceived as proof of this development to come.

Synthesis and Characterisation of In Situ Doped Silicon Nanoparticles

In situ boron, or phosphorous doped silicon nanoparticles were synthesised by pyrolysis of monosilane-diborane and monosilane-phosphane mixtures in free-space reactors. The studies were performed under atmospheric pressure in a laboratory reactor and a pilot plant for examination of scale-up effects. In the laboratory scale experiments, 1 vol % monosilane diluted in helium was used. The synthesis temperature varied between 600 and 800 ∘C. Pilot plant tests were run at 600 ∘C with 13.3 vol % silane diluted in hydrogen. The dopant content of the synthesised silicon powders was characterised by ETV-ICP-OES. Further investigations were carried out by using SEM, XRD, particle size analysis and FT-IR. An inhibition of the boron incorporation into the growing silicon lattice was found during the decomposition of the silane-diborane mixtures. This effect is a result of the low thermal stability of diborane. Silicon powders with higher boron contents and a wider particle size distribution leading to bigger particles, which showed no affinity to electrostatic charging, were obtained on the pilot plant scale. In phosphorus doping, reactor temperature was found crucial for the doping process.

Characteristics and Applications of Nanostructured Nitrides Synthesized by Vapor Phase Reactions

Gas phase ammonolysis of volatile metal chlorides at elevated temperatures is a favorable way to produce nitride or oxynitride nanopowders. Their composition as well as the physico-chemical properties is determined by reaction temperature, molar ratio of the reactants and the residence time of the gases in the reaction zone. Both single and multi component powders can be obtained. Typical particle sizes are in the range of 50 to 350 nm. The specific surface can reach values up to 300 m 2 /g. Microporous analysis revealed the presence of pores with a diameter between 0.6 and 0.7 nm in amorphous silicon nitride. The powders can be used, depending on the characteristics, as catalyst or basic catalyst support. The paper gives an overview about vapor phase synthesis of single and multi component nitrides as well as the use of amorphous silicon nitride as a basic catalyst support for dehydrogenation of propane.