Uwe Rodemerck

High-throughput synthesis and screening of catalytic materials: Case study on the search for a low-temperature catalyst for the oxidation of low-concentration propane

Abstract Low-temperature catalysts for the total combustion of low-concentration propane in air have been searched for applying a combinatorial approach including an optimization procedure based on a genetic algorithm. A 1st generation of catalysts was prepared by impregnation of TiO2 and Fe2O3 materials with randomly mixed solutions of eight individual compounds (H2[PtCl6]·xH2O, (NH4)2PdCl6, RhCl3·2H2O, RuCl3·H2O, H[AuCl4]·3H2O, Ag lactate, Cu(NO3)2, Mn(NO3)2) considered as potential catalytic compounds. After parallel testing of the 1st generation of the catalytic materials applying high-throughput testing equipment the most active catalysts were chosen to create a 2nd and after its testing a 3rd generation, respectively. A genetic algorithm was applied to set the compositions of the catalytic compounds of the 2nd and 3rd generation. Fe2O3 was not used as support for the succeeding generations since it lead to significantly inferior catalytic performances than TiO2. The optimization strategy led to improved catalysts. Most of the final material converted propane to CO2 at 150°C, the best ones oxidized propane even at 50°C. Furthermore, the goal was pursued to compare the performance of two different high-throughput testing equipments. In both cases the ranking of 45 catalysts was nearly the same.

The reaction network of the selective oxidation of n-butane on (VO)2P2O7 catalysts: Nature of oxygen containing intermediates

Abstract The reaction network of the partial oxidation of n-butane to maleic anhydride on (VO)2P2O7 has been investigated using steady-state and transient experiments in a Temporal-Analysis-of-Products (TAP) reactor under vacuum conditions to identify by mass spectrometry possible intermediate products and in a tubular fixed bed reactor at atmospheric pressure to derive information on the role of the detected and other potential intermediates in the reaction network. The oxidation of butane, butadiene, tetrahydrofuran, dihydrofuran, and furan has been studied in the TAP reactor and, additionally to these compounds, crotonaldehyde, crotonlactone, and malealdehydic acid were oxidized in the tubular flow reactor. From the results obtained it can be concluded that the main reaction pathway from butane to maleic anhydride proceeds via the intermediate products n-butenes, butadiene, crotonaldehyde, dihydrofuran, furan, and crotonlactone.

Parallel synthesis and fast screening of heterogeneous catalysts

We are presenting an effective method to prepare and test heterogeneous catalysts much faster than by the conventional way. A catalyst array was prepared via an incipient wetness method by combination of different amounts of Pt, Zr, and V on Al2O3 by means of an automatic liquid handler. For catalytic testing for methane oxidation a ceramic monolith reactor module, the channels of which contain the different catalyst compositions, was developed in which up to 250 catalyst compositions can be prepared and tested in parallel. Gas samples from each channel of the monolith were analysed sequentially by a mass spectrometer by moving the QMS inlet capillary into the channels using a three-dimensional positioning system which works at high temperatures. By comparison of the testing results with experiments carried out in flow reactors it is shown that the monolithic reactor is an efficient tool for fast screening of heterogeneous catalysts.