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Ni/SBA-15 meso-structured catalysts modified with chromium and CeO2 (Ni–Cr-CeO2/SBA-15) were utilized to produce hydrogen from glycerol steam reforming (GSR). The catalysts were synthesized by a one-pot hydrothermal process and extensively characterized by analytical techniques such as N2 adsorption–desorption (BET), H2-temperature programmed reduction (H2-TPR), powder X-ray diffraction (PXRD), inductively coupled plasma-optical emission spectrometry (ICP-OES), and transmission electron microscopy (TEM). The low-angle XRD reflections affirmed that the catalysts were crystalline and possessed a 2D-ordered porosity. The BET results depicted that all the catalysts exhibited a good surface area ranging from 633 to 792m2/g, and the pore sizes were consistently in the mesoporous range (between 3 and 5 nm). TEM analysis of both calcined and spent catalysts revealed that the metal active sites were embedded in the hybrid CeO2-SiO2 support. Overall, the Ni-based catalysts exhibited higher glycerol conversion -12Ni-SBA-15–99.9%, 12Ni3CeO2-SBA-15–89.4%, and 8Ni4Cr3CeO2-SBA-15–99.7%. Monometallic 12Ni/SBA-15 performed exceptionally well, while 12Cr/SBA-15 performed poorly with the highest 71.48% CO selectivity. For short-term GSR reactions, CeO2 addition to 12Ni/SBA-15 did not have any effect, whereas Cr addition resulted in a 32% decrease in H2 selectivity. The long-term stability studies of 12Ni-SBA-15 showed H2 selectivity of ~ 64% and ~ 98% glycerol conversion. However, its activity was short-lived. After 20–30 h, the H2 selectivity and conversion dropped precipitously to 40%. The doping of mesoporous Ni/SBA-15 with Cr and CeO2 remarkably enhanced the long-term stability of the catalyst for 12Ni3CeO2-SBA-15, and 8Ni4Cr3CeO2-SBA-15 catalyst which showed ~ 58% H2 selectivity and ~ 100% conversion for the entire 60 h. Interestingly, Cr and CeO2 seem to improve the shelf-life of Ni-SBA-15 via different mechanistic pathways. CeO2 mitigated Ni poisoning through coke oxidation whereas Cr bolstered the catalyst stability via maintaining a well-defined pore size, structural rigidity, and integrity of the heterogeneous framework, thereby restricting structural collapse, and hence retard sintering of the Ni active sites during the long-term 60 h of continuous reaction. Hydrogen generation from renewable biomass like glycerol could potentially serve as a sustainable energy source and could substantially help reduce the carbon footprint of the environment
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Nanoshaped CeO2 and SiO2 Supported Ru catalyst for Plasma Catalysis Chemical Looping Reactions
Chemical Looping Reaction is a key strategy to achieve both emission reduction and carbon utilization while producing various value-added chemicals, through redox reactions. Here we study the effect of nanoshape ceria supported Ru catalysts for plasma assisted Chemical Looping Reforming reduction step coupled with water splitting oxidation step reactions in the temperature range 150 ⁰C to 400 ⁰C at 1 atm pressure. The oxygen carrier/catalyst combination materials used are Ru/CeO2 nanorods (NR), Ru/CeO2 nanocubes (NC), Ru/SiO2 nanospheres (NS), and Ni-based perovskite mixed with CeO2. NRs and NCs showed the best catalytic performance followed by Ni-based perovskite and NS. Differences in the selectivity and reactivity for the NRs and NCs were noticed. The NCs showed slightly higher selectivity towards H2 formation during reduction step and lesser carbon deposition. From the analysis of data and literature, it is proposed that the spillover of species such as H adatoms and CHx radicals after activation at Ru sites into the CeO2 supports and lattice O mobility may be slightly faster in the case of NCs. During the oxidation step, the NR and NC materials showed increased H2 production by a factor of more than 4 when compared to Ni based perovskite material.
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- Award ID(s):
- 1655280
- PAR ID:
- 10221575
- Date Published:
- Journal Name:
- International journal of energy engineering
- Volume:
- 10
- Issue:
- 3
- ISSN:
- 2163-1905
- Page Range / eLocation ID:
- 67-79
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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