Carbon Nanotube Formation on Cr-Doped Ferrite Catalyst during Water Gas Shift Membrane Reaction: Mechanistic Implications and Extended Studies on Dry Gas Conversions
| Autor: | Devaiah Damma, Xinhui Sun, Antonios Arvanitis, Panagiotis G. Smirniotis, Junhang Dong, Vesselin Shanov, Noe T. Alvarez |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
02 engineering and technology Chemical vapor deposition 010402 general chemistry lcsh:Chemical technology 01 natural sciences Catalysis Water-gas shift reaction lcsh:Chemistry Crystallinity chemistry.chemical_compound water gas shift sulfur resistance lcsh:TP1-1185 Physical and Theoretical Chemistry Zeolite Membrane reactor carbon nanotubes Dry gas membrane reactor 021001 nanoscience & nanotechnology Cr-doped ferrite 0104 chemical sciences Chemical engineering chemistry lcsh:QD1-999 0210 nano-technology Syngas |
| Zdroj: | Catalysts Volume 10 Issue 8 Catalysts, Vol 10, Iss 927, p 927 (2020) |
| ISSN: | 2073-4344 |
| DOI: | 10.3390/catal10080927 |
| Popis: | A nanocrystalline chromium-doped ferrite (FeCr) catalyst was shown to coproduce H2 and multiwalled carbon nanotubes (MWCNTs) during water gas shift (WGS) reaction in a H2-permselective zeolite membrane reactor (MR) at reaction pressures of ~20 bar. The FeCr catalyst was further demonstrated in the synthesis of highly crystalline and dimensionally uniform MWCNTs from a dry gas mixture of CO and CH4, which were the apparent sources for MWCNT growth in the WGS MR. In both the WGS MR and dry gas reactions, the operating temperature was 500 ° C, which is significantly lower than those commonly used in MWCNT production by chemical vapor deposition (CVD) method from CO, CH4, or any other precursor gases. Extensive ex situ characterizations of the reaction products revealed that the FeCr catalyst remained in partially reduced states of Fe3+/Fe2+ and Cr6+/Cr3+ in WGS membrane reaction while further reduction of Fe2+ to Fe0 occurred in the CO/CH4 dry gas environments. The formation of the metallic Fe nanoparticles or catalyst surface dramatically improved the crystallinity and dimensional uniformity of the MWCNTs from dry gas reaction as compared to that from WGS reaction in the MR. Reaction of the CO/CH4 mixture containing 500 ppmv H2S also resulted in high-quality MWCNTs similar to those from the H2S-free feed gas, demonstrating excellent sulfur tolerance of the FeCr catalyst that is practically meaningful for utilization of biogas and cheap coal-derived syngas. |
| Databáze: | OpenAIRE |
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