A series of supported Ni catalysts (∼2 wt% Ni) were tested for the dry reforming of propane to synthesis gas reaction at 600 • C, C 3 H 8 :CO 2 :H 2 :N 2 (%) = 10:30:10:50, 1 atm and GHSV = 13333 Nml/(h g cat ). The support systems studied range from acidic (SiO 2 ) to amphoteric [Al 2 O 3 , Mg(Al)O] to basic oxides [MgO, CaO], with BET areas of 100, 100 (131 and 173), 117, and 16 m 2 /g, respectively. Ni particle size and reduction state was investigated by magnetic measurements, performed before and during catalytic testing. Support basicity was measured by CO 2 TPD. It was observed that the intrinsic activity of the catalysts (TOF) depends strongly on the Ni particle size (D) in the size range of 4.5-11 nm. As such, a TOF versus D plot showed an exponential inverse relationship, much more pronounced than previously reported for the methane dry reforming reaction. In turn, a volcano-type correlation was found between intrinsic catalyst activity and support basicity. As a result, the best catalytic performance, including a low selectivity to methane, was observed on the most dispersed Ni particles supported on Mg(Al)O. Key mechanistic features were derived from these observations.

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In this paper, we present a comprehensive study on how stacking faults, crystallite size, crystallite size distribution as well as shape and strain dictate the nature of the X-ray powder diffraction patterns of small (<20 nm) and large (>20 nm) cobalt (Co) nanoparticles. We provide a unique library of simulated diffractograms which can be used for fingerprint analysis. Likewise, the simulated data are used as a basis for structural refinements of experimentally obtained Xray powder diffractograms. We provide examples of using the library for fingerprint analysis and for full structural analysis of synthesized Co nanoparticles. Structural refinements presented in this study allow to reveal fine structural details that directly correlate to different behavior upon heating in a CO atmosphere relative to a H 2 or He atmosphere. All calculations were performed using the Discus package and the Debye scattering equation.

Catalysts with cobalt as the Fischer-Tropsch (FT) metal and nickel and/or rhenium as promoters on alumina of different pore sizes, a stabilized alumina, silica, or titania as supports were investigated for activity, selectivity, and deactivation up to 800 h of operation in a fixed-bed reactor. From the observed selectivities, there is no indication that nickel as a promoter with a loading up to 5 wt % influences the selectivities to higher hydrocarbons for low-temperature (<250 °C) cobalt FT synthesis. Nickel is found to have a profound impact on the catalytic activity, and the start of run activity, steady-state level, and deactivation rate are influenced. The freshly reduced catalyst is nearly inactive, but the activity increases rapidly to a stable level which is significantly higher than for catalysts without nickel. It appears that nickel can substitute rhenium as a reduction and activity promoter. The steady-state activity is maintained constant for a prolonged time, but expected deactivation commences after ca. 150 h time on stream.