Catalytic conversion of Biomass-derived Levulinic Acid! This review attempts to showcase an efficient catalytic system of levulinic acid reductive amination into pyrrolidones with core concerns on catalyst design and conditional optimization.

Abstract

Nowadays, the field of biomass conversion is gradually moving towards an encouraging stage. The preparation of nitrogen-containing chemicals using various biomass resources instead of fossil resources do not only reduce carbon emissions, but also diversify the products of biomass conversion, thus increasing the economic competitiveness of biomass refining systems. Levulinic acid (LA) can be used as a promising intermediate in biomass conversion for further synthesis of pyrrolidone via reductive amination. However, there are still many critical issues to be solved. Particularly, the specific effects of catalysts on the performance of LA reductive amination have not been sufficiently revealed, and the potential impacts of key conditional factors have not been clearly elucidated. In view of this, this review attempts to provide theoretical insights through an in-depth interpretation of the above key issues. The contribution of catalysts to the reductive amination of LA as well as the catalyst structural preferences for improving catalytic performance are discussed. In addition, the role of key conditional factors is discussed. The insights presented in this review will contribute to the design of catalyst nanostructures and the rational configuration of green reaction conditions, which may provide inspiration to facilitate the nitrogen-related transformation of more biomass platform molecules.

MnNb2O6 anode has attracted much attention owing to its unique properties for holding Li ions. Unluckily, its application as a Li-ion battery anode is restricted by low capacity because of the inferior electronic conductivity and limited electron transfer. Previous studies suggest that structure and component optimization could improve its reversible capacity. This improvement is always companied by capacity increments, however, the reasons have rarely been identified. Herein, MnNb2O6-C nanofibers (NF) with MnNb2O6 nanoparticles (~15 nm) confined in carbon NF, and the counterpart MnNb2O6 NF consisting of larger nanoparticles (40-100 nm) are prepared by electrospinning for clarifying this phenomenon. The electrochemical evaluations indicate that the capacity achieved by the MnNb2O6 NF electrode presents an activation process and a degradation in subsequence. Meanwhile, the MnNb2O6-C NF electrode delivers high reversible capacity and ultra-stable cycling performance. Further analysis based on electrochemical behaviors and microstructure changes reveals that the partial structure rearrangement should be in charge of the capacity increment, mainly including pseudocapacitance increment. This work suggests that diminishing the dimensions of MnNb2O6 nanoparticles and further confining them in a matrix could increase the pseudocapacitance-dominated capacity, providing a novel way to improve the reversible capacity of MnNb2O6 and other intercalation reaction anodes.

Fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are considered the most effective electrolyte additives for improving the solid electrolyte interphase (SEI) of Si-containing anodes while lithium difluorophosphate (LiDFP) is known to improve the interphases of cathode materials and graphite. Here, we combine VC, FEC, and different amounts of LiDFP in a highly-concentrated electrolyte to investigate the effect on Si-dominant anodes in detail. Cycle life tests, electrochemical impedance spectroscopy and rate tests with anode potential monitoring were conducted in Si/NCM pouch cells. The results reveal that adding LiDFP to the electrolyte improves all performance criteria of the full cells, with a concentration of 1 wt.% being the optimal value for most cases. Post-mortem analyses using scanning electron microscopy and x-ray photoelectron spectroscopy showed that a more beneficial SEI film was formed for higher LiDFP concentrations, which led to less decomposition of electrolyte components and a better-maintained anode microstructure.

Metal-organic frameworks-based electrocatalysts have been developed as highly desirable and promising candidates for catalyzing oxygen reduction reaction (ORR), which, however, usually need to be prepared at elevated temperatures and may suffer from the framework collapse in water environment largely preventing its industrial application. Herein, we demonstrate a facile low-temperature ion exchange method to synthesize Mn and Fe co-loaded Prussian blue analogues possessing core-shell structured frameworks and favorable water-tolerance. Among the catalysts prepared, the optimal HMPB-2.6Mn shows a high ORR electrocatalytic performance featuring a half-wave potential of 0.86 V and zinc-air battery power density of 119 mW cm-2, as well as negligible degradation up to 60 h, which are comparable to commercial Pt/C. Such an excellent electrocatalytic performance is attributed to the special core-shell-like structure with Mn concentrated in outer shell, and the synergetic interactions between Mn and Fe, endowing HMPB-Mn with outstanding ORR activity and good stability.

The synthesis and purification of pectin-based 2,5-furandicarboxylic acid methyl esters from gram-scale to kilogram-scale enables the valorisation of agricultural side streams into fully renewable polyesters.

Abstract

2,5-Furandicarboxylic acid (FDCA) is one of the most attractive emerging renewable monomers, which has gained interest especially in polyester applications, such as the production of polyethylene furanoate (PEF). Recently, the attention has shifted towards FDCA esters due to their better solubility as well as the easier purification and polymerisation compared to FDCA. In our previous work, we reported the synthesis of FDCA butyl esters by dehydration of aldaric acids as stable intermediates. Here, we present the synthesis of FDCA methyl esters in high yields from pectin-based galactaric acid using a solid acid catalyst. The process enables high substrate concentrations (up to 20 wt %) giving up to 50 mol % FDCA methyl esters with total furancarboxylates yields of up to 90 mol %. The synthesis was successfully scaled up from gram-scale to kilogram-scale in batch reactors showing the feasibility of the process. The stability of the catalyst was tested in re-use experiments. Purification of the crude product by vacuum distillation and precipitation gave furan-2,5-dimethylcarboxylate with a 98 % purity.

The decavanadate cluster ([V₁₀O₂₈]⁶⁻) is stabilized with the organic guanidinium (CN₃H₆ ⁺, Gdm⁺) cation through electrostatic and hydrogen bonding interactions. The resulting Gdm{V₁₀} cluster shows improved thermal properties and stability in liquid organic electrolytes, leading to better performance as an anode material for sodium-ion and lithium-ion batteries.

Abstract

Decavanadate ([V₁₀O₂₈]⁶⁻, {V₁₀}) clusters are a potential electrode material for lithium and post-lithium batteries; however, their low stability due to the solubility in liquid organic electrolytes has been challenging. These molecular clusters are also prone to transform into solid-state oxides at a moderate temperature needed in the typical electrode fabrication process. Hence, controlling the solubility and improving the thermal stability of compounds are essential to make them more viable options for use as battery electrodes. This study shows a crystal engineering approach to stabilize the cluster with organic guanidinium (Gdm⁺) cation through the hydrogen-bonding interactions between the amino groups of the cation and the anion. The comparison of solubility and thermal stability of the Gdm{V₁₀} with another cluster bearing tetrabutylammonium (Tba⁺) cation reveals the better stability of cation-anion assembly in the former than the latter. As a result, the Gdm{V₁₀} delivers better rate capability and cycling stability than Tba{V₁₀} when tested as anode material in a half-cell configuration of a sodium-ion battery. Finally, the performance of the Gdm{V₁₀} anode is also investigated in a lithium-ion battery full cell with LiFePO₄ cathode.

This review reports a comparison between Carbonates and Esters chemistry. Analysis of the experimental data led to propose a Model outlining the differences in energy profiles among the reaction mechanisms of these compounds. Several case studies were herein discussed so to corroborate the proposed theoretical energy model.

Abstract

This review reports on the competition/collaboration among intertwined base-catalyzed acyl cleavage bimolecular mechanism (B_Ac2)/base-catalyzed alkyl cleavage bimolecular mechanism (B_Al2) or the related acid catalyzed mechanisms A_Ac2/A_Al2 and A_Al1 concerning Carbonates chemistry also in comparison with Esters reactivity. A consistent analysis of the experimental data so far available in the literature led to proposing a theoretical Model outlining the differences in energy profiles among the above-mentioned reaction mechanisms. The reactions involving Carbonates are so tightly interconnected that the formation of the final product is driven by a precise not interfering sequence of B_Ac2-B_Al2 (or A_Al2-A_Ac2) mechanisms. When entropic effect (in cyclisations) or an anchimeric effect (mustard carbonates, isosorbide methylation) are involved, the difference in Gibbs activation energy is reduced allowing chemical transformations that would normally require higher temperatures. In these cases (intramolecular alkylation, cyclisation reaction, and alkylation by mustard carbonates) only a catalytic amount of base is required as the leaving group CH₃OCOO⁻ decomposes restoring the base. As Green Chemistry is concerned, syntheses with much lower environmental impact are achieved with Carbonates when compared with the corresponding ones involving Chlorine chemistry.

Which is better? The performance of 2-cyanopyridine and 2-furonitrile as a dehydrant has been compared in the CeO₂-catalyzed direct synthesis of dialkyl carbonates from CO₂ and various alcohols. The affinity of nitrile dehydrant and CeO₂ as well as bulkiness of alkyl chain in alcohols are important factors.

Abstract

The shift of equilibrium by removing water with nitrile dehydrants is crucial for CeO₂-catalyzed synthesis of dialkyl carbonates from CO₂ and alcohols. Two nitriles – 2-cyanopyridine and 2-furonitrile – were previously found as effective dehydrants, yet their detailed comparison as well as exploration of potential of 2-furonitrile remain insufficient. Herein, the performance of 2-cyanopyridine and 2-furonitrile was compared in the synthesis of various dialkyl carbonates. 2-furonitrile was found to be superior to 2-cyanopyridine in the synthesis of dialkyl carbonates from CO₂ and bulky or long-chain (≥C3) alcohols. Namely, the yield of diisopropyl carbonate (up to 50 %) achieved using CeO₂ and 2-furonitrile is comparable to or even higher than previously reported ones. Meanwhile, 2-cyanopyridine acted as a better dehydrant than 2-furonitrile in the synthesis of dimethyl carbonate and diethyl carbonate. The adsorption experiments and density functional theory calculations have indicated that the better performance of 2-furonitrile compared to 2-cyanopyridine in the synthesis of dialkyl carbonates from bulky or long-chain alcohols is due to the weaker interaction of 2-furonitrile with the CeO₂ surface. Such weak interaction of 2-furonitrile offers a larger reaction field on the catalyst surface for both CO₂ and alcohols.

Commercialization of photoelectrochemical (PEC) water-splitting devices requires the development of large-area, low-cost photoanodes with high efficiency and photostability. Herein, we address these challenges by using scalable fabrication techniques and porous transport layer (PTLs) electrode supports. We demonstrate the deposition of W-doped BiVO4 on Ti PTLs using successive-ionic-layer-adsorption-and-reaction methods followed by boron treatment and chemical bath deposition of NiFeOOH co-catalyst. The use of PTLs that facilitate efficient mass and charge transfer, allowed the scaling of the photoanodes (100 cm2) while maintaining ~90% of the performance obtained with 1 cm2 photoanodes for oxygen evolution reaction i.e. 2.10 mA cm-2 at 1.23 V vs. RHE. This is the highest reported performance to date. Integration with a polycrystalline Si PV cell leads to bias-free water splitting with a stable photocurrent of 208 mA for 6 h and 2.2% solar-to-hydrogen efficiency. Our findings highlight the importance of photoelectrode design towards scalable PEC device development.

The shift towards sustainable feedstocks for platform chemicals requires new routes to access functional molecules that contain heteroatoms, but there are limited bio-derived feedstocks that lead to heteroatoms in platform chemicals. Combining renewable molecules of different origins could be a solution to optimize the use of atoms from renewable sources. However, the lack of retrosynthetic tools makes it challenging to examine the extensive reaction networks of various platform molecules focusing on multiple bio-based feedstocks. In this study, a protocol was developed to identify potential transformation pathways that allow for the use of feedstocks from different origins. By analyzing existing knowledge on chemical reactions in large databases, several promising synthetic routes were shortlisted, with the reaction of D-glucosamine and pyruvic acid being the most interesting to make pyrrole-2-carboxylic acid (PCA). The optimized synthetic conditions resulted in 50% yield of PCA, with insights gained from temperature variant NMR studies. The use of substrates obtained from two different bio-feedstock bases, namely cellulose and chitin, allowed for the establishment of a PCA-based chemical space.