Abstract
H-ZSM-5 catalyst powders before and after a steaming post-treatment have been investigated during the Methanol-To-Hydrocarbons (MTH) process at 350 degrees C. Bulk and surface characterization techniques have been combined with in situ Scanning Transmission X-ray Microscopy (STXM) at the aluminum and carbon K-edge to study the changes in acidity, porosity, reactivity, and aluminum distribution upon steaming. It was found that steaming post-treatment has a positive impact on the stability of H-ZSM-5 without inducing important changes in the MTH activity and selectivity. The lower MTH stability of non-steamed H-ZSM-5 catalyst powder is related to the formation of poly-aromatic compounds in the outer regions of the catalyst particles, as probed with in situ STXM. In contrast, a limited amount of poly-aromatics was found in the outer rim of steamed H-ZSM-5 catalyst particles. These differences occur as a result of the generation of mesoporosity as well as the reduction in the number and strength of acid sites after steaming, as evidenced by the nanoscale imaging of adsorbed pyridine with STXM. (C) 2013 Elsevier Inc. All rights reserved.
Original language | English |
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Pages (from-to) | 185-193 |
Number of pages | 9 |
Journal | Journal of Catalysis |
Volume | 307 |
DOIs | |
Publication status | Published - Nov 2013 |
Funding
Dr. B. Watts and Dr. J. Raabe (both from the Swiss Light Source, Switzerland), Dr. T. Tyliszczak and Dr. A.L.D. Kilcoyne (both from the Lawrence Berkeley National Laboratory, USA) as well as Dr. P.S. Miedema (Utrecht University, The Netherlands) are kindly thanked for their contributions and fruitful discussions. K. Cats and H. van der Bij (both from Utrecht University, The Netherlands) are thanked for their help during STXM experiments. We thank NRSC-C (BMW), NWO-CW Top (BMW) and NWO-CW VICI (FMFdG) for financial support. S.T.'s Ph.D. grant is financed by inGAP, which receives funding from the Norwegian Research Council under Contract Number 174873.
Keywords
- Heterogeneous Catalysis
- Zeolites
- Methanol-to-hydrocarbons
- Coke formation
- In situ spectroscopy
- X-RAY SPECTROMICROSCOPY
- K-SHELL EXCITATION
- HZSM-5 ZEOLITES
- AROMATIC-MOLECULES
- CARBON
- CONVERSION
- DEALUMINATION
- SPECTROSCOPY
- DEACTIVATION
- NMR