Paweł Kowalik

The Evaluation of Synthesis Route Impact on Structure, Morphology and LT-WGS Activity of Cu/ZnO/Al2O3 catalysts

Four different techniques (co-precipitation, urea homogeneous precipitation, citrate sol–gel auto-combustion, solid state formate assisted) were used in preparation of a series of Cu/ZnO/Al2O3 catalysts, having a nominal composition: (Cu/Zn)mol = 2.5 and (Cu + Zn)/Almol = 3. The catalytic materials were investigated by various methods. The activity of the CuZnAl catalysts in the LT-WGS process was compared. The results revealed that the co-precipitation technique and subsequent thermal decomposition provided the Cu/ZnO/Al2O3 catalyst with the higher specific surface area and more advantageous surface morphology. It was shown that co-precipitation of hydroxycarbonate precursors at constant pH and their subsequent thermal treatment provided the most active WGS catalyst compared to other techniques.Graphical Abstract

The Effect of La 2 O 3 on Ni/Al 2 O 3 Catalyst for Methanation at Very Low CO x /H 2 Ratio

The effect of La2O3 on physicochemical and catalytic properties of Ni/Al2O3 catalysts for carbon oxides methanation was investigated. A series of model Ni–La–Al catalysts with a similar Ni/(Al + La) ratio and with a variable Ni/La ratio were prepared by coprecipitation method. The textural properties of catalysts, reducibility and reaction rate as well as specific activity and the apparent activation energies of carbon oxides methanation was determined. The results reveal a strong and beneficial influence of La2O3 on catalytic activity, despite the fact that their basic textural-surface properties were not substantially modified.Graphical Abstract

On the selection of the best polymorph of Al2O3 carriers for supported cobalt nano-spinel catalysts for N2O abatement: an interplay between preferable surface spreading and damaging active phase–support interaction

A series of cobalt spinel catalysts dispersed over various alumina supports (with varying alpha-, gamma-, delta- and theta-Al2O3 phase contents) were prepared and thoroughly characterized (XRF, XRD, μRS, SEM/TEM/EDX/SAED, TPR) and their reactivity was evaluated in low temperature N2O decomposition as a probe reaction. The observed significant differences in catalytic activities were discussed in terms of the supports nature, active phase dispersion, nanocrystal morphology and the alumina support–Co3O4 interactions. The more reactive amorphous phase as well as the gamma-, delta- and theta-Al2O3 phases gives rise to high dispersion of the spinel nanocrystals (∼10 nm) which is, however, sacrificed by the formation of mixed Co3−xAlxO4 spinels of much less activity. It was revealed that the best support for the deN2O catalyst is an α-Al2O3 phase of micrometric grain size and the optimal size of the Co3O4 nanocrystals is in the range of 20–30 nm. This catalyst was also found to be more resistant to H2O, NO and O2 contaminants in comparison to the catalysts based on γ-Al2O3.

THE EFFICIENCY OF THE GAVER-STEHFEST METHOD TO SOLVE OF ONE-DIMENSIONAL GAS FLOW MODEL

In this paper we examined the efficiency of one of the methods for numerical inversion of the Laplace transform: the Gaver-Stehfest method to find a solution to a onedimensional gas flow model with axial dispersion. The algorithm was used to determine values of the axial dispersion coefficients DL and Pèclet numbers Pe on the basis of the pulse tracer technique. The obtained results of Pèclet numbers indicate that the gas flow is neither plug flow nor perfect mixing under operation condition. Numerical results are provided to confirm the efficiency of the presented method. Calculations were performed with the use of the CAS program type (Maple®).