| 1. |
- Abdelaziz, Omar Y., et al.
(author)
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Oxidative Depolymerization of Kraft Lignin to Aromatics Over Bimetallic V–Cu/ZrO2 Catalysts
- 2023
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In: Topics in Catalysis. - 1022-5528. ; 66:17-18, s. 1369-1380
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Journal article (peer-reviewed)abstract
- Zirconia-supported vanadium–copper catalysts (VCux:yZr) were used for the oxidative depolymerization of softwood LignoBoost Kraft lignin (LB). Various VCux:yZr catalysts were prepared (x:y = 0:1, 1:4, 1:2, 3:4, 1:1, and 1:0) by incipient wetness impregnation, and reactions were performed in alkaline water at 150 °C under an O2 pressure of 5 bar for 10 min. 1H–13C HSQC NMR spectroscopy was used for product identification and quantification. The most promising catalyst was VCu1:2Zr, giving a total monomer yield of 9 wt% and the highest selectivity for vanillin (59%). This catalyst was characterized before and after use by N2 physisorption, XRD, TGA, SEM-EDS, and XPS. Cleavage of the main interunit linkages in LB, including the β-O-4 bonds and recalcitrant C–C bonds, was also observed. The findings of this study demonstrate the potential of the V–Cu/ZrO2 catalyst system in the production of value-added aromatics from technical lignin under relatively mild conditions. This would contribute to the more sustainable use of an underutilized side-stream in forest-based industries, provided catalyst reuse can be successfully demonstrated.
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| 2. |
- Chakrabarti, Kaushik, et al.
(author)
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Acceptorless dehydrogenation of 4-methylpiperidine by supported pincer-ligated iridium catalysts in continuous flow
- 2023
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In: Catalysis Science and Technology. - 2044-4753. ; 13:17, s. 5113-5119
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Journal article (peer-reviewed)abstract
- Finding alternative and sustainable ways to produce, store and convert energy is key for reducing fossil fuel-based CO2 emissions. In this transformation, hydrogen for energy storage and hydrogen-powered fuel cells for energy conversion can play important roles. However, storage of hydrogen itself is difficult and the concept of reversible liquid organic hydrogen carriers (LOHCs) has been proposed given the advantages of using liquid storage materials. A key part in the adaption of LOHCs is the catalyst design for efficient dehydrogenation of these hydrogen-carrying species. In this study, the use of silica- and alumina-supported POCOP-Ir systems for gas phase acceptorless dehydrogenation of 4-methylpiperidine (an LOHC with 6.1 wt% hydrogen) is investigated in a continuous-flow system with a high TON. To increase stability and reactivity, a new POCOP-Ir complex with two anchors was designed and found to be highly active in the dehydrogenation of 4-methylpiperidine with ∼91 000 turnovers in 45 h. In addition, this catalyst showed a maintained activity with a TOF of 1684 h−1 after 45 h.
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