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Franczyk E.,New Chemical Syntheses Institute INS | Golbiowski A.,New Chemical Syntheses Institute INS | Borowiecki T.,New Chemical Syntheses Institute INS | Borowiecki T.,Maria Curie Sklodowska University | And 2 more authors.
Chemical and Process Engineering - Inzynieria Chemiczna i Procesowa | Year: 2015

A proper selection of steam reforming catalyst geometry has a direct effect on the efficiency and economy of hydrogen production from natural gas and is a very important technological and engineering issue in terms of process optimisation. This paper determines the influence of widely used seven-hole grain diameter (ranging from 11 to 21 mm), h/d (height/diameter) ratio of catalyst grain and Sh/St (hole surface/total cylinder surface in cross-section) ratio (ranging from 0.13 to 0.37) on the gas load of catalyst bed, gas flow resistance, maximum wall temperature and the risk of catalyst coking. Calculations were based on the one-dimensional pseudo-homogeneous model of a steam reforming tubular reactor, with catalyst parameters derived from our investigations. The process analysis shows that it is advantageous, along the whole reformer tube length, to apply catalyst forms of h/d = 1 ratio, relatively large dimensions, possibly high bed porosity and Sh/St ≈ 0.30-0.37 ratio. It enables a considerable process intensification and the processing of more natural gas at the same flow resistance, despite lower bed activity, without catalyst coking risk. Alternatively, plant pressure drop can be reduced maintaining the same gas load, which translates directly into diminishing the operating costs as a result of lowering power consumption for gas compression.

Konkol M.,New Chemical Syntheses Institute INS | Kondracka M.,New Chemical Syntheses Institute INS | Kowalik P.,New Chemical Syntheses Institute INS | Prochniak W.,New Chemical Syntheses Institute INS | And 4 more authors.
Applied Catalysis B: Environmental | Year: 2016

Ag nanoparticles in a Yb2O3 matrix catalyzed the direct decomposition of N2O to the elements. Our investigations included X-ray powder diffraction and electron microscopy; they revealed a remarkable dependence of the catalytic activity on the catalyst preparation method that influenced the size of Ag crystallites. Simple precipitation followed by calcination resulted in the formation of a catalyst with rather large Ag crystallites, which showed low activity. In contrast, thermal decomposition of the mixed-metal Ag-Yb coordination polymer provided the Ag/Yb2O3 catalytic system with distinctly smaller Ag crystallites. The coordination-polymer derived catalyst exhibited much higher activity in the deN2O process at moderate temperature range 400-500 °C. © 2016 Elsevier B.V.

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