Radoslaw Ciesielski

The effect of gold on modern bimetallic Au–Cu/MWCNT catalysts for the oxy-steam reforming of methanol

Copper and gold doped copper catalysts supported on multi-walled carbon nanotubes were prepared by wet impregnation and deposition–precipitation methods, respectively. The catalysts were tested in the oxy-steam reforming of methanol (OSRM) and characterized by XRD, SEM-EDS, TOF-SIMS, thermo-gravimetric analysis and temperature-programmed desorption of ammonia. The reactivity results showed the promotion effect of gold on the activity and selectivity of the copper catalysts in the OSRM. The formed Cu–Au alloy as an active phase was responsible for the activity and selectivity improvement of the bimetallic catalysts in the oxy-steam reforming of methanol. The formation of an Au–Cu alloy was confirmed by the XRD, TOF-SIMS and SEM-EDS techniques. The reducibility and acidity of the tested catalysts are important factors, which influence the activity of the copper and gold–copper catalysts.

Novel Pd–Cu/ZnAl2O4–ZrO2 Catalysts for Methanol Synthesis

Monometallic Cu and bimetallic Pd–Cu catalysts promoted by ZrO2 were prepared using impregnation method. The physicochemical properties of catalytic systems were investigated using BET, scanning electron microscopy–energy dispersive spectrometry, temperature programmed reduction-H2, X-ray diffraction, Fourier transform infrared techniques. Catalytic activity was studied in fixed bed reactor under high pressure (4.8 MPa). The results show that addition both Pd and ZrO2 increases the methanol yield. Zirconium oxide improved the dispersion and reducibility of the copper catalysts. The presence of adsorption species attributed to b-HCOO–Zr, b-HCO3–Zr, m-CO3–Zr species on the surface of ZrO2 promoted catalysts was confirmed. The high activity of promoted palladium catalysts is explained by synergistic effect between Pd and Cu.Graphical Abstract

Promoted ternary CuO-ZrO2-Al2O3 catalysts for methanol synthesis

AbstractTernary CuO-ZrO2-Al2O3 catalysts promoted by palladium or gold were prepared and tested in CO hydrogenation reaction at 260°C under elevated pressure (4.8 MPa). The promotion effect of palladium or gold addition on the physicochemical and catalytical properties of CuO-ZrO2-Al2O3 catalysts in methanol synthesis (MS) was studied. The catalysts were characterized by BET, XRD, TPR-H2, TPD-NH3 methods. The BET results showed that the ternary system CuO-ZrO2-Al2O3 had the largest specific surface area, cumulative pore volume and average pore size in comparison with the promoted catalysts. The yield of methanol can be given through the following sequence: 5%Pd/CuO-ZrO2-Al2O3 > CuO-ZrO2-Al2O3 > 2%Au/CuO-ZrO2-Al2O3. We also found that the presence of gold or palladium on catalyst surface has strong influence on the reaction selectivity. The high selectivity of gold doped ternary catalyst is explained by the gold-oxide interface sites created on the catalyst surface and the acidity of those systems. The higher selectivity to methanol in the case of the palladium catalyst is explained by the spillover effect between Pd and CuO.

Fischer–Tropsch synthesis over various Fe/Al2O3–Cr2O3 catalysts

Monometallic iron supported catalysts were prepared by the impregnation method and tested in Fischer–Tropsch (F–T) synthesis. The activity tests performed in the studied reaction showed that the composition of the catalyst strongly influences the reactivity of the catalytic systems in the F–T reaction. It was also found that the system which showed the highest content of iron species on the catalyst surface exhibited the highest yield in F–T reaction. In addition, the most active catalyst also showed high specific surface area, high total acidity value and the highest amount of iron species on the catalyst surface. The analysis of the liquid product of F–T synthesis confirmed the occurrence of aliphatic, branched and unsaturated linear hydrocarbons.

Carbon Deposits Formed on the Surface of Ru–Ni Catalysts During the Mixed Reforming of Methane Process

Monometallic nickel and bimetallic ruthenium–nickel catalysts supported onto aluminum oxide without additives and aluminum oxide modified with MgO and CaO were prepared by an impregnation method. The catalysts were tested in the process of the mixed reforming of methane, and their properties were characterized by thermogravimetry, scanning electron microscopy, and X-ray diffractometry. The total organic carbon content of the catalysts was also measured. The promoting effect of ruthenium and structural promoters on the catalytic activity of Ni/Al2O3 was confirmed. The Ru–Ni/MgO–Al2O3 catalyst exhibited the highest stability and activity; this fact can be explained by the increased adsorption of methane on the surface of ruthenium–nickel clusters.

Supported Ru−Ni Catalysts for Biogas and Biohydrogen Conversion into Syngas

Catalytic properties of monometallic Ni and bimetallic Ru–Ni supported on Al2O3, CaO–Al2O3, and MgO–Al2O3 have been studied in mixed reforming of methane. Physicochemical properties of the catalytic systems have been studied by X-ray diffraction, scanning electron microscopy with energy dispersive spectroscope and temperature-programmed reduction by hydrogen. It has been shown that, of all the studied samples, the highest conversion of methane and carbon dioxide is achieved in the presence of the Ru−Ni/MgO–Al2O3 bimetallic catalyst. Temperature-programmed reduction has confirmed the effect of hydrogen spillower from ruthenium to NiO. The formation of Ru–Ni alloy has also been found.

Bimetallic Pd–Cu/ZnO–Al2O3 and Pd–Cu/ZrO2–Al2O3 catalysts for methanol synthesis

Monometallic copper and bimetallic palladium-copper catalysts supported on ZnO–Al2O3 and ZrO2–Al2O3 were prepared by conventional impregnation method and tested in methanol synthesis reaction under elevated pressure (3.5 MPa) in gradientless reactor at 220°C. The physicochemical properties of prepared catalytic systems were studied using BET, X-ray, TPR-H2, TPD-NH3 techniques. The promotion effect of palladium on catalytic activity and selectivity of copper supported catalyst in methanol synthesis reaction was proven. The highest activity of this system is explained by the Pd–Cu alloy formation.

The features of CNT growth on catalyst-content amorphous alloy layer by CVD-method

This work is devoted to the CVD-synthesis of arrays of carbon nanotubes (CNTs) on Co-Zr-N-(O), Ni-Nb-N-(O), Co- Ta-N-(O) catalytic alloy films from gas mixture of C2H2+NH3+Ar at a substrate temperature of about 550°C.Heating of the amorphous alloy causes its crystallization and squeezing of the catalytic metal onto the surface. As a result, small catalyst particles are formed on the surface. The CNT growth takes place after wards on these particles. It should be noted that the growth of CNT arrays on these alloys is insensitive to the thickness of alloy film, which makes this approach technically attractive. In particular, the possibility of local CNT growth at the ends of the Co-Ta-N-(O) film and three-level CNT growth at the end of more complex structure SiO2/Ni-Nb-N-O/SiO2/Ni-Nb-N-O/SiO2/Ni-Nb-N-O/SiO2 is demonstrated.