| 1. |
- Abdelaziz, Omar Y., et al.
(författare)
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On the Oxidative Valorization of Lignin to High-Value Chemicals : A Critical Review of Opportunities and Challenges
- 2022
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 15:20
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Forskningsöversikt (refereegranskat)abstract
- The efficient valorization of lignin is crucial if we are to replace current petroleum-based feedstock and establish more sustainable and competitive lignocellulosic biorefineries. Pulp and paper mills and second-generation biorefineries produce large quantities of low-value technical lignin as a by-product, which is often combusted on-site for energy recovery. This Review focuses on the conversion of technical lignins by oxidative depolymerization employing heterogeneous catalysts. It scrutinizes the current literature describing the use of various heterogeneous catalysts in the oxidative depolymerization of lignin and includes a comparison of the methods, catalyst loadings, reaction media, and types of catalyst applied, as well as the reaction products and yields. Furthermore, current techniques for the determination of product yields and product recovery are discussed. Finally, challenges and suggestions for future approaches are outlined.
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| 2. |
- Polukeev, Alexey V., et al.
(författare)
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Iridium Catalyzed Dehydrogenation in a Continuous Flow Reactor as a Tool Towards Practical On-Board Hydrogen Generation From LOHCs
- 2022
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Ingår i: ChemSusChem. - : Wiley. - 1864-564X .- 1864-5631. ; 15:8
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Tidskriftsartikel (refereegranskat)abstract
- To enable the large-scale use of hydrogen fuel cells for mobility applications, convenient methods for on-board hydrogen storage and release need to be developed. A promising approach is liquid organic hydrogen carriers (LOHCs), since these are safe, available on a large scale and compatible with existing re-fuelling infrastructure. Usually, LOHC dehydrogenation is carried out in batch-type reactors by transition metals and their complexes and suffers from slow H 2 release kinetics and/or inability to reach high energy density by weight due to low conversion or the need to dilute the reaction mixture. Here we report the use of a continuous flow reactor in combination with a heterogenized iridium pincer complex, which enables a tremendous increase in LOHC dehydrogenation rates. Thus, dehydrogenation of isopropanol is performed in a regime that in terms of gravimetric energy density, hydrogen generation rate and precious metal content is potentially compatible with applications in a fuel-cell powered car.
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| 3. |
- Robinson, Ada Josefina, et al.
(författare)
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Techno-economic optimization of a process superstructure for lignin valorization
- 2022
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524. ; 364
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Tidskriftsartikel (refereegranskat)abstract
- Lignin, the most abundant aromatic biopolymer on Earth, is often considered a biorefinery by-product, despite its potential to be valorized into high-added-value chemicals and fuels. In this work, an integrated superstructure-based optimization model was set up and optimized using mixed-integer non-linear programming for the conversion of technical lignin to three main biobased products: aromatic monomers, phenol–formaldehyde resins, and aromatic aldehydes/acids. Several alternative conversion pathways were simultaneously compared to assess the profitability of lignins-based processes by predicting the performance of technologies with different TRL. Upon employing key technologies such as hydrothermal liquefaction, dissolution in solvent, or high-temperature electrolysis, the technical lignins could have a market value of 200 €/t when the market price for aromatic monomers, resins, and vanillin is at least 2.0, 0.8, and 15.0 €/kg, respectively. When lower product selling prices were considered, the aromatic monomers and the resins were not profitable as target products.
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| 4. |
- Umar, Yusuf, et al.
(författare)
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A renewable lignin-derived bio-oil for boosting the oxidation stability of biodiesel
- 2022
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Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481. ; 182, s. 867-878
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Tidskriftsartikel (refereegranskat)abstract
- The valorisation of lignin is being increasingly recognised to improve the economics of pulp and paper making mills. In the present study, an integrated lignin–glycerol valorisation strategy is introduced with an overarching aim for enhancing the process value chains. LignoBoost kraft lignin was subjected to base-catalysed depolymerisation using glycerol as a co-solvent. The generated bio-oil was used as a renewable additive to biodiesel for enhancing its oxygen stability. The influence of three independent parameters including temperature, time and glycerol amount on lignin depolymerisation was investigated. Response surface methodology was applied to design the experiments and to optimise the process for maximising the yield and antioxidant impact of bio-oil. The results showed that glycerol has a positive qualitative and quantitative impact on the produced bio-oil, where an enhancement in the yield (up to 23.8%) and antioxidant activity (up to 99 min induction period) were achieved using the PetroOxy method (EN16091). The addition of 1 wt% bio-oil to biodiesel has led to an improvement in the oxidation stability over a neat sample of up to ∼340%, making it compliant with European standard (EN14214). The proposed process presents a biorefinery paradigm for the integrated utilisation of waste cooking oil, lignin and glycerol.
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