Cubic SrTiO3 particles are obtained by precipitation from an aqueous gel suspension. The gel suspension
is prepared by hydrolyzing a TiOCl2 solution with NaOH and adding SrCl2. The addition of citric acid
leads to spherical particles. The particle size can be tailored in the range 80−1400 nm by varying the
temperature and the concentration. A careful control of the synthesis conditions is essential for producing
particles with a narrow size distribution. The results of HRTEM and ED investigations provide strong
evidence that the oriented aggregation of small (4−5 nm) nanocrystals is the dominant growth mechanism
for the formation of the observed SrTiO3 particles. The primary nanocrystals self-assemble in a highly
oriented fashion, producing defective single-crystal particles. The above results show that the directional
aggregation process can be controlled by changing the temperature and concentration of the suspension
as well as by adding organic molecules, obtaining SrTiO3 particles with a controlled size and shape.
This short critical review summarises and analyses the developments in Fischer-Tropsch catalysis using bimetallic alloys. We introduce a simple notation for such catalysts, and monitor the reports of synergistic effects and composition/performance relationships. Special attention is given to CoFe alloys on a variety of supports, and to the effects of catalyst preparation methods and pre-treatment conditions. The key drawbacks in comparing the large amount of data available on Fischer-Tropsch catalysis are the high dimensionality of the problem and the lack of long time-on-stream studies. Based on the new understanding coming from characterisation studies of supported bimetallic particles, we propose a structured approach for effectively studying Fischer-Tropsch catalysis.
Audio cassettes hold the key to enhancing Fischer–Tropsch catalysis. Catalysts based on ultra‐thin cobalt shells surrounding cheap iron oxide cores (see picture) are developed, an approach previously optimized for preparing magnetic tape for audio cassettes. These particles are easily made on a large scale, and are excellent Fischer–Tropsch catalysts, giving good diesel fractions.
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