Catalytic Properties and surface Reactivity of Intermetallic Compounds
Zusammenfassung der Projektergebnisse
The CAPRICE project aimed to advance the field of the knowledge-based development in heterogeneous catalysis. By bridging the expertise from surface science with high quality sample synthesis and catalytic tests under industrial relevant conditions. For this project two reactions were picked for their large socio-economic importance, namely methanol steam reforming and the semi-hydrogenation of acetylene. Methanol is an efficient and easy to handle energy carrier, thus predicted to play an important part in a fossil-free hydrogen economy. The semi-hydrogenation of acetylene play a large role in the purification of ethylene in the production of polyethylene, where acetylene acts as a catalyst poison for the Ziegler-Natta catalyst. The compounds AlCo, Al 5Co2 and Al 9Co2 were investigated in the semi-hydrogenation of acetylene under industry-like conditions. The catalytic activity were fairly low for all three compound, activity was higher in samples prepared under argon in contrast to preparation in air. The difference in activity presumably being due to oxidation of the surface. The compound A5Co2 showed reasonable high activity when prepared under argon, however the results suffered from low reproducibility. Due to the low activity of Al-Co compounds focus were shifter to investigating the influence of the microstructure on the catalytic properties of Al13Fe4. Preliminary result had shown that the degree of twinning influence the catalytic properties. Single crystalline slabs with varying twin density were tested in catalysis, however no influence by twinning along c* could be proven. InPd was successfully investigated under operando conditions showing a dynamic behaviour of the near surface region, both in terms of crystal structure (GIXRD) and electronic structure (NAP-XPS). The operando studies confirmed an orientational dependence on the stability towards reactive atmosphere. The difference in near-surface stability coupled together with a difference in catalytic properties of the investigated orientations. To test for differences in catalytic properties of different crystallographic orientations under industrially relevant conditions a new reactor was developed within the project. While the reactor was developed with single-crystalline slabs of InPd in mind, the flexibility of the design allows large variation in sample shape and size. Due to the activity of InPd being rather low compared to the related and proven compound ZnPd part of the focus was shiftet to synthesis development of ZnPd. This refocus resulted in a new synthesis procedure for Zn-based intermetallic compounds with a high degree of control over the final product. The method also shows promise to be applicable to other systems with a large difference in vapour pressure. Samples produced by the new synthesis route possessed larger grains compared to previously produced samples and crystallographic twinning could clearly be seen. As a detailed material understanding is desired for a knowledge based approach and microstructure were in parallel investigated in the case of Al13Fe4, the twinning in ZnPd were deemed a suitable target for investigation. It could be shown that twinning occurs in {101} planes in the structure, it was also observed that the c/a ratio is changing in the vicinity of the twin boundary. These experimental observations were confirmed by quantum chemical calculations, the chemical bonding in real space were investigated by ELI. The combined expertise form the different partner groups led to a highly successful project, the combined number of 18 peer reviewed publications and additional four manuscripts under preparation could not have been achieved by the groups working individually.
Projektbezogene Publikationen (Auswahl)
- The Intermetallic Compound ZnPd and Its Role in Methanol Steam Reforming, Catal. Rev.: Sci. Eng. 55, 2013, 289
M. Armbrüster, M. Behrens, K. Föttinger, M. Friedrich, É. Gaudry, S.K. Matam, H.R. Sharma
(Siehe online unter https://doi.org/10.1080/01614940.2013.796192) - Chemical Bonding in Zn-based Intermetallic Compounds with the CuTi or the CsCl Type of Structures, Z. Anorg. Allg. Chem. 640, 2014, 753
S. Alarcón Villaseca, D. Kandaskalov, É. Gaudry, M. Armbrüster
(Siehe online unter https://doi.org/10.1002/zaac.201300583) - Intermetallic Compounds in Heterogeneous Catalysis - A Quickly Developing Field, Sci. Technol. Adv. Mater. 15, 2014, 034803
M. Armbrüster, R. Schlögl, Yu. Grin
(Siehe online unter https://doi.org/10.1088/1468-6996/15/3/034803) - Physical Properties of the InPd Intermetallic Catalyst, Intermetallics 55, 2014, 56
M. Wencka, M. Hahne, A. Kocjan, S. Vrtnik, P. Kozelj, D. Korze, Z. Jaglicic, M. Soric, P. Poptevic, J. Ivkov, A. Smontara, P. Gille, S. Jurga, P. Tomes, S. Paschen, A. Ormeci, M. Armbrüster, Y. Grin, J. Dolinsek
(Siehe online unter https://doi.org/10.1016/j.intermet.2014.07.007) - The Atomic Structure of Low-Index Surfaces of the Intermetallic Compound InPd, J. Chem. Phys. 143, 2015, 074705
G.M. McGuirk, J. Ledieu, É. Gaudry, M.-C. de Weerd, M. Hahne, P. Gille, D.C.A. Ivarsson, M. Armbrüster, J. Ardini, G. Held, F. Maccherozzi, A. Bayer, M. Lowe, K. Pussi, R.D. Diehl, V. Fournée
(Siehe online unter https://doi.org/10.1063/1.4928650) - Controlled Synthesis and Catalytic Properties of Supported In-Pd Intermetallic Compounds, J. Catal. 340, 2016, 49
M. Neumann, D. Teschner, A. Knop-Gericke, W. Reschetilowski, M. Armbrüster
(Siehe online unter https://doi.org/10.1016/j.jcat.2016.05.006) - ZnPd/ZnO Aerogels as Potential Catalytic Materials, Adv. Funct. Mater. 26, 2016, 1014
C. Ziegler, S. Klosz, L. Borchardt, M. Oschatz, S. Kaskel, M. Friedrich, R. Kriegel, T. Keilhauer, M. Armbrüster, A. Eychmüller
(Siehe online unter https://doi.org/10.1002/adfm.201503000)
