Max Planck Institutes in Mülheim report the first artificial synthesis of ferripyrophyllite under exceptionally mild conditions as successful result from their joint research work

Joint research results were recently published in Dalton Transactions.

The joint research project of the two Max Planck Institutes in Mülheim started by a chance discovery: When performing catalytic reactions in water as a solvent, Dr. Yunxiang Qiao, postdoctoral researcher in the team of Dr. Nils Theyssen of the Kohlenforschung and member of the department of Prof. Walter Leitner of the neighboring MPI CEC worked with two different reactors. The autoclaves, manufactured by the Precision Engineering Department of the Kohlenforschung, were both made of nickel-based alloy, but one autoclave used a stirrer shaft made of iron-based V4A stainless steel while the second variant used only a magnetic, Teflon-coated stirrer core. Surprisingly, when the researcher worked with SBA-15, a mesoporous form of silicon oxide SiO2, an iron silicate was formed in the reactor with the stainless steel stirring shaft. The substance did not appear in any analytical database to that date and set off a successful collaboration of specialists from both Max Planck Institutes in Mülheim, who combined their expertise and instrumental equipment to identify ferripyrophyllite formed under particularly mild conditions for the first time.

The presumed phase transformation of SBA-15 into the new iron silicate was shown by transmission electron microscopy (TEM) of the MPI für Kohlenforschung. Mössbauer spectroscopy from the Chemical Energy Conversion provided further important data on the chemical environment of the iron. Extensive structural investigations by the Powder Diffractometry and Surface Spectroscopy group and other groups from the Heterogeneous Catalysis Department of the Kohlenforschung and the Heterogeneous Reactions Division of the MPI CEC served to understand the structure and function of the iron silicate in detail. It was demonstrated that only an iron source (e.g. iron powder), a SiO2 source (for example SBA-15, MCM-41 or even silica) and water are needed to produce iron silicate at surprisingly mild conditions of 100 °C and the vapor pressure of water. Other previously known iron silicates usually require pressures of around 1000 bar and significantly higher temperatures.

In the meantime, the researchers carried out catalytic tests and succeeded in incorporating further metals into the structure of the iron silicate. Ferripyrophyllite proved to be a promising catalyst support material that is also interesting for use as a catalyst in iron-catalyzed reactions.

The research results, summarized by Dr. Nils Theyssen and Professor Walter Leitner, were recently published in the journal Dalton Transactions of the Royal Chemical Society. The Mülheim contribution to catalysis research was highlighted as a topic for the Inside Front Cover.

You can find more information on the joint research work of both Mülheim MPIs in this news article of the MPI for Chemical Energy Conversion.

Publication: Yunxiang Qiao, Nils Theyssen, Bernd Spliethoff, Jan Folke, Claudia Weidenthaler, Wolfgang Schmidt, Gonzalo Prieto, Cristina Ochoa-Hernández, Eckhard Bill, Shengfa Ye, Holger Ruland, Ferdi Schüth, Walter Leitner (2021) Synthetic ferripyrophyllite: preparation, characterization and catalytic application. Dalton Trans., 2021,50, 850-857.

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