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ZB 16 - Dynamics of nanocrystal structure induced by surface chemistry (Z.Kaszkur) |
Funding
01.02.2019 - 31.12.2020
Research project 2018/29/N/ST4/01465 granted by National Science Centre of Poland
"Structure dynamics of surface of catalytic systems based on nanocrystalline gold loaded on oxide supports in chemoselective Reduction of (Volatile) α,β-Unsaturated Carbonyl compounds (R-(V)ABUC)"
Principal Investigator: Maciej Zieliński, PhD Eng.
The main idea of this project was inspired by curiosity to answer the question how supported heterogeneous gold (Au) catalysts work. They are going to be tested in reaction of Reduction of (Volatile) α,β–Unsaturated Carbonyl compounds (R-(V)ABUC) with gaseous hydrogen. Among possible outcomes of this reaction, production of unsaturated alcohol (allylic alcohol) is the most challenging. The main aim concentrates on explaining why gold catalysts can be efficiently applied to production of derivatives of unsaturated carbonyl compounds.
As bulk gold does not interact readily with surroundings even if its surface was modified and developed, a hypothesis was formulated that the whole gold particle structure reconstruction is necessary in order that gold becomes a chemically active species. In contrast to bulk, in which any distortion created on the surface can be dissipated and compensated in the volume of the (poly)crystal, surface of a nanocrystal is a significant and, thus, important part of its structure. Following this concept, any disturbance of the equilibrium state of the surface should also affect deeper parts of the particle structure as a result of the attempt to compensate the influence of external stimulus.
One of the best techniques to track cyclic structural changes happening under reaction conditions is in operando Nanocrystalline X-Ray Diffraction (NXRD), which has been established and developed in our laboratory. This technique is based on standard Powder X-Ray Diffraction (PXRD), but is arranged into an in-operando setup and is coupled with Mass Spectrometry (MS). Our customised measurement strategy allows for acquisition of diffraction patterns (DP) while MS spectra are monitored on-line and other experimental parameters (including temperatures and gas flows) are logged at the same time. After extracting crystal structure description from DP the reversible changes of structure parameters of gold and support are presented as a function of time, chemical reaction output, etc.
Additionally, adsorbates on the surface will be identified by in-situ Infrared Spectroscopy (IR) and their interactions with the surface will be correlated with crystal structure evolution. Crystal lattice will be also investigated at the atomic level by Transmission Electron Microscopy (TEM).
The results of this research will show dynamics of the surface which is as a whole the active centre of the catalyst. New point of view on the catalytic systems together with new data are likely to be the crucial step towards development of this branch of chemistry.
The project summary is available also on the official site of the National Science Centre of Poland: http://ncn.gov.pl/sites/default/files/listy-rankingowe/2018-03-15/streszczenia/412873-en.pdf