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The Cover Feature shows high-performing and stable Cu/NiAlO_x catalysts derived from NiAl-hydrotalcite for continuous catalytic conversion of ethanol into butanol, which is one of the pivotal processes in biorefinery for the production of renewable fuels and value-added chemicals. In their Research Article, Y. Tan, W. Luo, Y.-J. Ding and co-workers report that significant enhancement in catalytic performance in terms of activity, selectivity and stability, can be attained by adding Cu properly into the NiAl-hydrotalcite. An optimal compromise between the ethanol conversion and butanol selectivity can be sustained over the optimal Cu/NiAlO_x catalyst for 1000 h during the long-term stability test under moderate reaction condition, reflecting one of the state-of-the-art performances for non-noble metal-based heterogeneous catalysts in this Guerbet coupling process. More information can be found in the Research Article by Y. Tan, W. Luo, Y.-J. Ding and co-workers.

Efforts to deepen the understanding of sustainable development have resulted in the concept of green carbon science. In this Review, technological achievements in green carbon science are discussed, with a focus on pilot testing, industrial demonstrations, and commercial applications beyond the laboratory stage.

Abstract

The concept of green carbon science is to promote the goal of achieving carbon neutrality, the importance and urgency of which have been well-recognized and received worldwide attention. Carbon neutrality has become the focus of research work in many fields, and correspondingly, a growing number of papers and publications have been published over the last few years. However, since carbon neutralization is a real problem that urgently requires technical solutions, the transition from fundamental research to practical applications must be accelerated. A number of research teams are bold in putting things into practice and blazing new trails. This Review summarizes the recent technological developments within the framework of green carbon science, focusing on conducted pilot tests, industrial demonstrations, and commercial applications beyond the laboratory stage.

Nature Synthesis, Published online: 22 August 2022; doi:10.1038/s44160-022-00161-x

Mission impossible: Mechanosynthesis is erroneously perceived as an enabling tool for only making greener well-known solution-based processes. Modern mechanochemistry is, above all, an effective tool to open synthetic paths not accessible by following conventional and well-known pathways already reported in the literature for the classical chemistry in solution. Mechanical stimuli promote uncharted reaction pathways, making it possible to design and develop effective, successful synthetic protocols previously classified as “impossible reactions”.

Abstract

Mechanochemical transformations have made chemists enter unknown territories, forcing a different chemistry perspective. While questioning or revisiting familiar concepts belonging to solution chemistry, mechanochemistry has broken new ground, especially in the panorama of organic synthesis. Not only does it foster new “thinking outside the box”, but it also has opened new reaction paths, allowing to overcome the weaknesses of traditional chemistry exactly where the use of well-established solution-based methodologies rules out progress. In this Review, the reader is introduced to an intriguing research subject not yet fully explored and waiting for improved understanding. Indeed, the study is mainly focused on organic transformations that, although impossible in solution, become possible under mechanochemical processing conditions, simultaneously entailing innovation and expanding the chemical space.

Catalysts, Vol. 12, Pages 783: Selective Synthesis of Levulinic Ester from Furfural Catalyzed by Hierarchical Zeolites

Catalysts doi: 10.3390/catal12070783

Authors: Sancler C. Vasconcelos Luiz F. C. Pinhel Vinicius G. C. Madriaga Vinicius Rossa Leyliane G. S. Batinga Domingos S. A. Silva Rodrigo D. dos Santos André V. H. Soares Ernesto A. Urquieta-González Fabio Barboza Passos Rajender S. Varma Thiago M. Lima

Furfural is a platform molecule that can be catalytically converted using a cascade series of reactions into levulinic esters, essential compounds used as fuel additives. Bifunctional catalysts containing Lewis and Brønsted acid sites such as zeolites are commonly used for these conversions. However, microporous zeolites often present diffusional restriction due to the size similarity of furfural and other molecules to the zeolites’ micropores. Thus, incorporating mesopores in these materials through post-synthetic protocols is a promising pathway to circumventing these limitations. This study presents the creation of hierarchical beta and mordenite using Si or Al removal and their employment in the furfural conversion to isopropyl levulinate (PL). Mordenite zeolite did not produce satisfactory mesopores, while the beta was more efficient in generating them by both acid and alkaline treatments. Beta zeolite treated in an alkaline solution presented larger mesopores (14.9 and 34.0 nm), maintaining a total acidity value close to its parent zeolite and a higher Lewis/Brønsted ratio. The combination of these features led to an improved diffusion of bulkier products and the highest furfural conversion (94%) and PL selectivity (90%), suggesting that a post-modification of beta zeolites produced efficient catalysts for upgrading abundantly available furfural.

Hydrogenation catalysis: A homogeneous Cu(I) catalyst with high selectivity (>99%) and activity (TON=4 000), under relatively mild reaction conditions (24 h, 140 °C) using a base-free system using H₂ (300 psi) as a reductant, and a low catalytic load (0.025 mol%) under optimized conditions in the hydrogenation of levulinic acid to γ-valerolactone is reported, along with full characterization of the copper catalytic precursor.

Abstract

We report the first well-defined homogeneous copper-based catalyst for levulinic acid (LVA) hydrogenation using complex [(PPh₃)₂Cu(k²-O,O-LVA)] as a copper source and (1,2-bis(diisopropyl phosphino)ethane (dippe) as an ancillary ligand. This catalytic precursor has high activity in LVA hydrogenation and yields γ-valerolactone (GVL) under relatively mild reaction conditions (24 h, 140 °C) in a base-free system using H₂ (300 psi) as a reductant. Under optimized conditions, GVL was obtained with excellent yield (>99 %) and selectivity (>99 %) using a low catalytic load (0.025 mol %), allowing a TON=4000.

Nature Chemistry, Published online: 23 June 2022; doi:10.1038/s41557-022-00974-5

Synfacts 2022; 18: 0773-
DOI: 10.1055/s-0041-1737652

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