Stefan Kaluza

A Novel Synthesis Route for Cu/ZnO/Al2O3 Catalysts used in Methanol Synthesis: Combining Continuous Consecutive Precipitation with Continuous Aging of the Precipitate

A novel continuous method for the preparation of a ternary Cu/ZnO/Al2O3 catalyst based on a cascade of micromixers and a tubular aging reactor is presented as a promising alternative route to the conventional batch process. Its application, in combination with immediate spray drying, enables monitoring of the formation of the final precursor by exchange reactions between initially separated phases during the aging step. These exchange reactions were successfully simulated by consecutive precipitation by using micromixers in series as analytical tool. After 60 min of continuous aging, calcination, and reduction, a catalyst is produced that exhibits an almost equal mass‐related activity in methanol synthesis compared to a commercial catalyst and an area‐related activity that is about 50 % higher.

The synthesis of Nb-doped TiO2 nanoparticles by spray drying: an efficient and scalable method

Nb-doped TiO2 nanoparticles were prepared by a continuous spray drying process using ammonium niobate (V) oxalate and titanium oxysulfate as water-soluble precursors. The structural and electronic properties were investigated using thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. Nb was found to be mainly incorporated as Nb5+ into the TiO2 lattice resulting in a charge compensation by Ti vacancies. The characterization results indicate that Nb was homogeneously distributed within the titania lattice, and that the surface segregation of Nb, which is commonly observed for Nb-doped TiO2, was significantly less pronounced. The high homogeneity and the lower extent of surface segregation originate from the efficient atomization of homogeneous precursor solutions and the fast evaporation of the solvent in the spray drying process. As a result, the ion mobility is diminished and spheres of well-mixed precursor materials are formed. Using the continuous spray drying process followed by a controlled heat treatment, the phase composition, the crystal size and the surface area of the Nb-doped TiO2 nanoparticles are easily adjustable.

On the precipitation mechanism and the role of the post-precipitation steps during the synthesis of binary ZnO–Al2O3 composites with high specific surface area

Zinc oxide, aluminium oxide and binary ZnO–Al2O3 composites were synthesized using a novel preparation method that combines continuous precipitation in a microreactor with an immediate spray drying process. The sequence of the post-precipitation processes as well as the type of drying can therefore be investigated in detail and turn out to be crucial parameters to achieve high specific surface areas. By optimizing those unit operations the formation of hydrotalcite during the synthesis can be suppressed resulting in an increase of the BET surface area up to 144 m2 g−1 for the co-precipitated, washed, freeze-dried and subsequently calcined Zn–Al precursor.

Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation

Ordered mesoporous materials are promising catalyst supports due to their uniform pore size distribution, high specific surface area and pore volume, tunable pore sizes, and long-range ordering of the pore packing. The evaporation-induced self-assembly (EISA) process was applied to synthesize mesoporous mixed oxides, which consist of cobalt ions highly dispersed in an alumina matrix. The characterization of the mesoporous mixed cobalt-aluminum oxides with cobalt loadings in the range from 5 to 15 wt% and calcination temperatures of 673, 973, and 1073 K indicates that Co2

German Catalysis on an International Scale in Weimar

Over the years, the Annual Meeting of the German Catalysis Society (GeCatS), which traditionally takes place in Weimar, has become a constant in the conference calendar of every German catalysis researcher. This year’s meeting (March 12th– 14th) covered a huge range of catalysis, including recent research topics such as thermal, bio-, and photocatalysis. The latter was even put into practice, with the sunshine catalyzing scientific discussion and collaborative initiatives in the adjacent Weimarhalle park! This year’s conference was not only record-breaking with respect to the high temperatures but the scientific program itself. 582 participants joined this year’s conference (in comparison to 519 the year before), in which 38 oral presentations, including five plenary lectures with topics from academia and industry, and 288 posters were presented. For the first time, all oral presentations were given in English, reflecting the conference’s ever-increasing international character and significance. Furthermore, two poster workshops for emission reduction and selective hydrogenation were organized by YounGeCatS, in which selected poster contributors highlighted their research in short oral presentations. A high number of contributions focused on renewable resources and sustainability, for example, biomass conversion, carbon dioxide utilization, and photocatalysis, confirming the topical character of the meeting and reflecting the important role of catalysis in current and future strategies. In addition to the scientific program, 22 companies presented their latest developments and equipment related to catalysis research and catalyst characterization throughout the conference. In Remembrance of Helmut Knçzinger

A novel continuous approach for the synthesis and characterization of pure and mixed metal oxide systems applied in heterogeneous catalysis

Abstract An extensive set of characterization methods is required to study the processes occurring during the evolution of the initially amorphous precursor towards the complex Cu/ZnO/Al 2 O 3 system. A novel preparation method was therefore developed that provides the possibility of a systematic study of all components in the different stages of the precipitation of the ternary catalyst. As a result, a continuously operating synthesis route was established as an alternative to the industrially applied process.