Supported gold- and silver-based catalysts for the selective aerobic oxidation of 5-(hydroxymethyl)furfural to 2,5-furandicarboxylic acid and 5-hydroxymethyl-2-furancarboxylic acid

The sustainable synthesis of two important intermediates relevant for the production of bio-based polymers, 2,5-furandicarboxylic acid (FDCA) and 5-hydroxymethyl-2-furancarboxylic acid (HFCA), via oxidation of 5-(hydroxymethyl)furfural (HMF) was investigated using supported gold- and silver-based catalysts in water with air as the oxidant. High yields and selectivities for the production of FDCA (89%) and HFCA (≥98%) were achieved under the optimized reaction conditions with Au/ZrO2 and Ag/ZrO2 catalysts, respectively. While FDCA was mainly formed in the presence of gold catalysts at a maximum productivity of 67 molFDCA h−1 molAu−1, silver catalysts showed a remarkably high activity in aldehyde oxidation producing HFCA in almost quantitative yields with a maximum productivity of 400 molHFCA h−1 molAg−1. By variation of the reaction parameters, the Au/ZrO2 catalyst could be tuned to produce also HFCA, whereas the Ag/ZrO2 catalyst exclusively produced HFCA in a wide range of reaction parameters. The observed differences in catalyst selectivities can be taken as a starting point for further mechanistic investigation on the oxidation of HMF, contributing to a fundamental understanding of this reaction which is particularly important for establishing the production of bio-based polymers

Role of Iron on the Structure and Stability of Ni3.2Fe/Al2O3 during Dynamic CO2 Methanation for P2X Applications

An energy scenario, mainly based on renewables, requires efficient and flexible Power-to-X (P2X) storage technologies, including the methanation of CO₂. As active Ni⁰ surface sites of monometallic nickel-based catalysts are prone to surface oxidation under hydrogen-deficient conditions, we investigated iron as “protective” dopant. A combined operando X-ray absorption spectroscopy and X-ray diffraction setup with quantitative on-line product analysis was used to unravel the structure of Ni and Fe in an alloyed Ni-Fe/Al₂O₃ catalyst during dynamically driven methanation of CO₂. We observed that Fe protects Ni from oxidation and is itself more dynamic in the oxidation and reduction process. Hence, such “sacrificial” or“protective” dopants added in order to preserve the catalytic activity under dynamic reaction conditions may not only be of high relevance with respect to fine-tuning of catalysts for future industrial P2X applications but certainly also of general interest

Quantum disordered ground state for hard-core bosons on the frustrated square lattice

We investigate the phase diagram of hard-core bosons on a square lattice with competing interactions. The hard-core bosons can be represented also by spin-1/2 operators and the model can therefore be mapped onto an anisotropic $J_1$-$J_2$-Heisenberg model. We find the N\'eel state and a collinear antiferromagnetic state as classical ordered phases to be suppressed for small ferromagnetic exchange terms $J_{1,2}^{x,y}$ and a ferromagnetic phase which orders in the x-y-plane for large $J_{1,2}^{x,y}$. For an intermediate regime the emergence of new quantum states like valence bond crystals or super-solids is predicted for similar models. We do not observe any signal for long-range order in terms of conventional order or dimer correlations in our model and find an exponential decay in the spin correlations. Hence, all evidence is pointing towards a quantum disordered ground state for a small region in the phase diagram.Comment: 8 pages, 9 figures; version 3 includes erratum Phys. Rev. B 84, 219902(E) (2011): correction of formulas in Sec. III and replacement of "DPT transition line" in Fig. 1, (no other changes

Direct Catalytic Route to Biomass-Derived 2,5-Furandicarboxylic Acid and Its Use as Monomer in a Multicomponent Polymerization

Efficient synthesis of valuable platform chemicals from renewable feedstock is a challenging, yet essential strategy for developing technologies that are both economical and sustainable. In the present study, we investigated the synthesis of 2,5-furandicarboxylic acid (FDCA) in a two-step catalytic process starting from sucrose as largely available biomass feedstock. In the first step, 5-(hydroxymethyl)furfural (HMF) was synthesized by hydrolysis and dehydration of sucrose using sulfuric acid in a continuous reactor in 34% yield. In a second step, the resulting reaction solution was directly oxidized to FDCA without further purification over a Au/ZrO$_{2}$ catalyst with 84% yield (87% selectivity, batch process), corresponding to 29% overall yield with respect to sucrose. This two-step process could afford the production of pure FDCA after the respective extraction/crystallization despite the impure intermediate HMF solution. To demonstrate the direct application of the biomass-derived FDCA as monomer, the isolated product was used for Ugi-multicomponent polymerizations, establishing a new application possibility for FDCA. In the future, this efficient two-step process strategy toward FDCA should be extended to further renewable feedstock

Solutions for global marine litter pollution

Since the 1950s the amount of plastics in the marine environment has increased dramatically. Worldwide there is a growing concern about the risks and possible adverse effects of (micro) plastics. This paper reflects on the sources and effects of marine litter and the effects of policies and other actions taken worldwide. Current knowledge offers a solid basis for effective action. Yet, so far the effects of policies and other initiatives are still largely insufficient. The search for appropriate responses could be based on possible interventions and profound understanding of the context specific factors for success. Moreover, the scope, timeframe and dynamics of all initiatives are distinctly different and orchestration at all levels, in close cooperation with one another is currently lacking

Direct Catalytic Route to Biomass-Derived 2,5-Furandicarboxylic Acid and Its Use as Monomer in a Multicomponent Polymerization

Efficient synthesis of valuable platform chemicals from renewable feedstock is a challenging, yet essential strategy for developing technologies that are both economical and sustainable. In the present study, we investigated the synthesis of 2,5-furandicarboxylic acid (FDCA) in a two-step catalytic process starting from sucrose as largely available biomass feedstock. In the first step, 5-(hydroxymethyl)furfural (HMF) was synthesized by hydrolysis and dehydration of sucrose using sulfuric acid in a continuous reactor in 34% yield. In a second step, the resulting reaction solution was directly oxidized to FDCA without further purification over a Au/ZrO2 catalyst with 84% yield (87% selectivity, batch process), corresponding to 29% overall yield with respect to sucrose. This two-step process could afford the production of pure FDCA after the respective extraction/crystallization despite the impure intermediate HMF solution. To demonstrate the direct application of the biomass-derived FDCA as monomer, the isolated product was used for Ugi-multicomponent polymerizations, establishing a new application possibility for FDCA. In the future, this efficient two-step process strategy toward FDCA should be extended to further renewable feedstock

Mindergie: A pervasive learning game for pro-environmental behaviour at the workplace

This chapter reports about a pervasive learning game to increase the environmental awareness and pro-environmental behaviour at the workplace. Based on a discussion of the theoretical background and related work we introduce the game design and game elements. Results of a formative evaluation study are presented and discussed. Results show that incentive mechanisms are less important than challenging game components that involve employees in proposing solutions for energy conservation at the workplace. Conclusions are drawn for future games and energy conservation activities at the workplace.This project has been partially funded by a SURFnet innovation grant for sustainable ICT solutions and partially by the Welten Institute – Research Centre for Learning, Teaching and Technology of the Open University of the Netherlands