Announcements

CHEMISTRY SEMINAR by Cem Akatay

Author: COLLEGE OF SCIENCES
Time: 14:30
Location: SCI 103

KOÇ UNIVERSITY CHEMISTRY SEMINAR
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Speaker          : Cem Akatay, Senior Research Scientist, Honeywell UOP

Title                : Structural and chemical analysis of catalysts at the nanometer scale

Date                : September 17, 2019, Thursday
Time               : 14:30
Cookie&Tea  : SCI 103 14:15
Place               : SCI 103

 

Abstract         :

 

Characterization of materials at the nanometer scale is of great importance in the development of high-performance functional materials. The adaptation of the aberration correction has improved the spatial resolution for transmission electron microscopy down to sub-Ångstrom levels [1]. The drastic improvements in the X-ray detectors and electron spectrometers have expanded the high-resolution imaging capabilities into chemical imaging with sub-nanometer resolution and enabled single atom sensitivity where possible [2-3]. These advanced capabilities empower researchers to a great degree in their quest to understand the materials behavior better. This talk will focus on the use of aberration corrected transmission electron microscopy imaging and chemical analysis in identifying the failure mechanisms of catalysts.

Pre-mature deactivation of catalysts is an industrially relevant problem and visualizing how catalysts “age” during operation provides great insights on the deactivation mechanisms. The material of choice for this study was a zeolite. Zeolites are crystalline aluminosilicates that are used as industrial adsorbents and catalysts thanks to their high surface area and pore network of well-defined cages and channels [4]. In this case, the zeolite was embedded with metal nanoparticles resulting in a nano-composite material which serves as a bifunctional catalyst for hydrocarbon chemistry [5]. During the catalytic reaction, carbonaceous species deposit on the material which are regarded as coke. Coking can hinder diffusion of the reactants limiting the accessibility of the active sites and hence is detrimental to the performance of the catalyst [6]. In this work, the location of the coke was determined at the nanometer level and chemically different types of carbon were found at different sites of the catalyst. This information was used to identify the specific mechanism of catalyst deactivation and thus shed light onto the inner workings of the catalytic nanomaterial.

References:

[1] DA Muller et al, Science 319 (2008), p.1073-1076

[2] RS Ruskin, Z Yu, and N Grigorieff, J. Struct. Biol. 184 (2013), p. 385

[3] JL Hart, AC Lang, C Trevor, R Twesten, ML Taheri, Microsc. Microanal. 22 (S3) (2016), p. 336

[4] Broach, R. and Kulprathipanja, S. (2010) Mixed-Matrix Membranes, in Zeolites in Industrial Separation and Catalysis (ed S. Kulprathipanja), Wiley-VCH

[5] Kanazirev, V, J. Chem. Soc. Chem. Communications (1990) 712-713

[6] Sanchez, S. I.; Moser, M. D.; Bradley, S. A. ACS Catal. 2014, 4, 220– 228

 

Short Bio                  :

 

Cem Akatay obtained B.Sc in Materials Science and Engineering at Sabanci University, Turkey. He continued his studies in the United States of America and obtained Ph.D in Materials Science and Engineering at the Purdue University focusing on the characterization of catalyst nanomaterials. He joined Honeywell UOP in 2014 and is responsible for the advanced characterization of UOP materials at their R&D headquarters in Des Plaines, IL.