In situ characterization of Fischer–Tropsch catalysts: a review

Abstract

In the field of heterogeneous catalysis research, in situ and operando characterization techniques, i.e. characterization techniques which can be applied under realistic reaction conditions and ideally on a working catalyst, become essential in order to generate new knowledge and understanding of structure performance relationships. Only this knowledge will enable researchers to develop or rather design new catalysts for existing and novel processes without relying on an ‘educated guess’ approach. In combination with ever improving theoretical predictions, operando characterization techniques are expected to be the main drivers in catalyst research and associated material science in the foreseeable future. Fischer–Tropsch (FT) catalyst systems, and specifically the iron based catalysts, are highly dynamic under reaction conditions, making deductions on structure-activity relationships difficult when relying on conventional characterization techniques. In addition, various deactivation mechanisms, such as oxidation, poisoning, sintering, attrition and phase separation have been observed. As such, the FT synthesis encompasses several challenges experienced in some form or other in most catalytic applications and material science studies. The present review therefore aims to provide a comprehensive account of characterization techniques employed under (quasi) in situ and operando conditions for FT catalysts. Together with a description of the respective technique and a critical discussion of the employed reaction cell, the actual research conducted is briefly discussed. We hope that this combination will enable readers not only to get a good impression of the capabilities and limitations of the respective technique and available instrumentation but also to understand their applicability in catalysis research and maybe to be inspired to push current boundaries.

Direct View of Cr Atoms Doped in Anatase TiO2(001) Thin Film

“…The area ratio of L 3 /L 2 is estimated to be 0.79, which is in agreement with the reported experimental value of 0.8 for Ti 4+ [48,50]. L 2 (and L 3 ) edges are further split into two peaks due to the crystal field interaction, where Ti-O octahedron splits the degenerate Ti 3d states into two states of t 2g and e g [51,52]. The energy separation of peaks A1 and A2 is 5.3 eV, indicates the oxidation state of Ti is +4 again [51].…”

Hydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometry

“…Furthermore, the wide size distribution of this spent sample shows the presence of a few particles that are in the range of 20-70 nm. This particle growth can be attributed to the combination of the high H 2 O concentration and the high reaction temperatures reached, which has also been reported for other metal-based catalysts [32].…”

Crack Statististics and Stress Analysis of Thick GaN on Patterned Silicon Substrate

“…Few models have been developed on stress relaxation on patterned heteroepitaxial films where it was shown that the patterned film as well as the patterned substrate has a large effect on relaxation of the film stress. [22][23][24][25] Hu's model showed that due to having free edges the patterned film on the substrate releases film stress through the edges. While the model of Fischer and Richter [24] showed that if the substrate is patterned it can release more stress of the patterned film.…”

“…[22][23][24][25] Hu's model showed that due to having free edges the patterned film on the substrate releases film stress through the edges. While the model of Fischer and Richter [24] showed that if the substrate is patterned it can release more stress of the patterned film. In our work, the stress distribution of the patterned GaN and underlying patterned silicon substrate also showed the similar results shown in Figure 5.…”