Während der Röstung von Kaffee laufen zahlreiche Reaktionen ab. Darunter entstehen unerwünschte Stoffe wie Acrylamid, Furan, 2‐ und 3‐Methylfuran, 2,5‐Dimethylfuran (Methylfurane). Das Ziel der ...vorliegenden Arbeit war es, Röstungen und Behandlungsverfahren zu identifizieren, bei denen eine gleichzeitige Minimierung von Acrylamid und Furan/Methylfuranen möglich ist. Hierzu wurden Vietnam Robusta Röstkaffees auf die Gehalte der genannten Analyten mittels optimierter und validierter Methoden mit GC‐MS untersucht.
Industriell wurden Rohkaffees unter Variation der Zeit und der Temperatur auf die Röstfarben hell, mittel und dunkel geröstet. Die Untersuchungen zeigten das gegenläufige Verhalten der Bildung von Acrylamid und Furan/Methylfuranen. Die höchsten Gehalte an Acrylamid wurden in hellen sowie kurzen Röstungen und die von Furan/Methylfuranen in dunklen sowie langen Röstungen ermittelt.
Weiterhin wurden extreme Röstprofile im Vergleich zu o.g. Röstserien untersucht. Bezüglich der Gehalte von Furan und Methylfuranen konnten deutliche Unterschiede festgestellt werden, jedoch ohne eine charakteristische Tendenz. Acrylamid zeigte höhere Gehalte in den Kaffees, die zu Beginn mit niedrigerer und zum Ende hin mit höherer Energiezufuhr geröstet wurden. Betrachtet wurden ebenfalls die Einflüsse von Rohkaffee‐Vorbehandlungen und einer Röstkaffee‐Nachbehandlung. Bei diesen Röstexperimenten konnte deutlich erkannt werden, dass die Behandlungsart differente Einflüsse auf die Bildung der Analyten ausübt. Insgesamt konnten keine Röstparameter ermittelt werden, mit denen eine gleichzeitige Minimierung von Acrylamid und Furan/Methylfuranen möglich ist.
Weiterhin wurden die bei der Röstung gebildeten Furanabkömmlinge: Furfurylalkohol, 5‐Hydroxymethylfurfural, 2‐Furancarbonsäure und 5‐Hydroxymethyl‐2‐furancarbonsäure in den o. a. Kaffees mittels HPLC‐DAD untersucht. Eine deutliche Abhängigkeit von den Röstgraden und Röstzeiten konnte auch bei diesen festgestellt werden.
An Anderson-type polyoxometalate (NH4)3H6CoMo6O24 in deep eutectic solvents exhibited outstanding catalytic performance for the selective aerobic oxidation of HMF to FFCA. It is potentially a ...promising and highly environmentally friendly approach for biomass conversion.
Invited for this month′s cover is the group of Yves Queneau at the University of Lyon. The cover image shows superb natural architectures with spherical symmetrical shapes evoking that of organized ...systems, micelles, and bubbles symbolizing creativity and imagination in the molecular design of biobased surfactants. The Review highlights the emerging use of 5‐hydroxymethylfurfural and other biobased furans as scaffolds toward novel amphiphiles. The Review itself is available at 10.1002/cssc.202102660.
“Carbohydrate‐derived platform molecules such as furanic aldehydes are inspiring scaffolds…” This and more about the story behind the research that inspired the Cover image is presented in the Cover Profile. Read the full text of the corresponding research at 10.1002/cssc.202102660. View the Front Cover here: 10.1002/cssc.202201010.
The electrosynthesis from 5‐hydroxymethylfurfural (HMF) is considered a green strategy to achieve biomass‐derived high‐value chemicals. As the molecular structure of HMF is relatively complicated, ...understanding the HMF adsorption/catalysis behavior on electrocatalysts is vital for biomass‐based electrosynthesis. The electrocatalysis behavior can be modulated by tuning the adsorption energy of the reactive molecules. In this work, the HMF adsorption behavior on spinel oxide, Co3O4 is discovered. Correspondingly, the adsorption energy of HMF on Co3O4 is successfully tuned by decorating with single‐atom Ir. It is observed that compared with bare Co3O4, single‐atom‐Ir‐loaded Co3O4 (Ir‐Co3O4) can enhance adsorption with the CC groups of HMF. The synergetic adsorption can enhance the overall conversion of HMF on electrocatalysts. With the modulated HMF adsorption, the as‐designed Ir‐Co3O4 exhibits a record performance (with an onset potential of 1.15 VRHE) for the electrosynthesis from HMF.
Single atoms of Ir are anchored on Co3O4 for efficient electro‐oxidation of 5‐hydroxymethylfurfural (HMF). It is found that an isolated Ir atom can optimize the adsorption configuration of HMF molecules on catalysts and accelerate HMF oxidation.
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•We focus on productions of HMF, LA, and FAME over solid catalysts from biomass.•Challenges of using actual biomass and waste streams were highlighted in this work.•Constituents of ...biomass could interfere with and deactivate catalysts.•Complete evaluation of solid catalysts on actual biomass conversion is encouraged.
Biomass conversion to value-added chemicals and fuels over heterogeneous catalysts is one of the top issues in green chemistry. This review focuses on recent advances in the application of solid catalysts for producing three prominent bio-based chemicals, hydroxymethylfurfural (HMF), levulinic acid (LA) and fatty acid methyl ester (FAME) from biomass materials, respectively. Our work highlights the perspectives and challenges during the conversion of actual biomass, including the impact of complex constituents and impurities of biomass on the solid catalysts, mass transfer limitation in the reactions, and the stability and deactivation of the solid catalysts. Transformation of solid catalysts from research to industrialization necessitates future work on identification of interactions between the catalysts and actual biomass, and comprehensive evaluation of the suitability of the catalysts in the reaction systems.
The conversion of renewable compounds to versatile platform molecules over environmentally friendly heterogeneous catalysts is a major challenge. Zeolites stand as active, selective, and reusable ...solid catalysts for various acid-catalyzed reactions involved in the one-pot cascade transformation of polysaccharides to 5-hydroxymethylfurfural (HMF), a platform molecule opening the way to various valuable chemicals. However, the acidity-performance relationships of zeolite catalysts in HMF synthesis have not been fully elucidated. Here, we have addressed the effect of acid site nature in zeolite catalysts for sucrose-to-HMF transformation by comparing the performance of conventional Al-substituted IWW zeolite with that of Sn-, Zr-, and Ge-containing zeolite catalysts of the same structure. Ge-associated acid sites were found to exhibit superior HMF selectivity compared to Sn, Zr, and Al acid centers, while experiencing evolution into Brønsted acid centers during the catalytic run. The conversion of sucrose over germanosilicate zeolites enhances with increasing catalyst pore diameter or decreasing crystal size. Specifically, the extra-large pore Ge-UTL catalyst, featuring intersecting 14- and 12-ring pores (crystal size 10 × 20 × <1 μm), and large-pore Ge-IWW with 12-, 10- and 8-ring pores (crystal sizes of 1 μm) showed a yield of targeted HMF comparable to or even exceeding the values previously reported for homogeneous or heterogeneous catalysis (54 % after 3 h at 120 °C). Ge-IWW catalyst demonstrated reusability across a minimum of 3 catalytic runs, while in situ structural transformation precluded stable performance of Ge-UTL catalyst in the repetitive catalytic cycles. The results of this study highlight zeolites with uncharacteristic chemical compositions as active, selective, and reusable catalysts for highly demanding applications in biomass valorization.
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•Acidity-performance relationships of zeolite catalysts in sucrose-to-HMF transformation.•Weak Ge acid sites outperform stronger Sn, Zr, and Al acid centers.•In situ formation of Ge Brønsted acid sites during the catalytic run.•Zeolites with uncharacteristic chemical compositions for biomass valorization.
Paired electrosynthesis is a promising technology with the potential to generate value‐added products at both electrodes in a cost‐effective manner. Herein, 3D vanadium nitride (VN) and Pd/VN hollow ...nanospheres are successfully fabricated and coupled to carry out simultaneous electrocatalytic oxidation (ECO) and electrocatalytic hydrogenation (ECH) of 5‐hydroxymethylfurfural (HMF) into 2, 5‐furandicarboxylic acid (FDCA) and 2,5‐bishydroxymethyl‐tetrahydrofuran (DHMTHF), respectively. VN shows excellent ECO performance with high HMF conversion (≥98%), FDCA selectivity (≥96%), and faradaic efficiency (≥84%) after a stability test, and Pd/VN achieves high ECH selectivity for DHMTHF at ≥88% and an HMF conversion of ≥90%, with a faradaic efficiency of ≥86%. VN and Pd/VN incorporated into a membrane electrode assembly in a paired electrolysis system shows potential for large‐scale biomass conversion and upgrading. Theoretical calculations reveal that the higher performance of VN for the production of ECO can be attributed to its lower d‐band center level relative to the Fermi level compared to that of V2O5, which favors HMF chemisorption and activation. This study paves the way for developing paired electrosynthesis technologies with the potential for biomass utilization and energy conversion.
A paired electrolysis system is employed for simultaneous electrocatalytic oxidation of 5‐hydroxymethylfurfural to 2, 5‐furandicarboxylic acid and electrocatalytic hydrogenation to 2, 5‐bishydroxymethyl‐tetrahydrofuran using VN and Pd/VN as electrocatalysts with excellent activity. This strategy opens up a new avenue for biomass utilization and energy conversion.
