Understanding the Mechanocatalytic Conversion of Biomass: A Low‐Energy One‐Step Reaction Mechanism by Applying Mechanical Force

Amirjalayer, Saeed; Fuchs, Harald; Marx, Dominik

doi:10.1002/anie.201811091

Cited by 27 publications

(22 citation statements)

References 47 publications

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“…This difference is probably associated with the increased component of frictional forces provided by the Emax mill. Tentatively, the frictional forces would counteract the impact forces by realigning the polymer chains, thus reverting the conformational changes required for the activation of cellulose towards depolymerizing reactions ( Schüth et al, 2014 ; Amirjalayer et al, 2019 ).…”

Section: Resultsmentioning

confidence: 99%

“…These routes are known as mechanocatalytic depolymerization (MCD). Recently, atomistic modeling provided in-depth insight into the impact of mechanical forces on the MCD of cellulose and lignin ( Amirjalayer et al, 2019 ). On the one hand, mechanical forces are proposed to produce conformational changes in the pyranic ring, activating latent states in the MCD of cellulose, facilitating the glycosidic bond cleavage ( Schüth et al, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

“…On the one hand, mechanical forces are proposed to produce conformational changes in the pyranic ring, activating latent states in the MCD of cellulose, facilitating the glycosidic bond cleavage ( Schüth et al, 2014 ). In this manner, compared to a thermally activated process, the mechanochemical conversion was predicted to decrease the activation barrier by a factor of five ( Amirjalayer et al, 2019 ). On the other hand, the cleavage of the most common lignin linkages ( β -O-4 aryl alkyl ether) seems to be favored by stretching forces ( Patel et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

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Kinetic Energy Dose as a Unified Metric for Comparing Ball Mills in the Mechanocatalytic Depolymerization of Lignocellulose

Keßler

Rinaldi

2022

Front. Chem.

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Mechanochemistry utilizes mechanical forces to activate chemical bonds. It offers environmentally benign routes for both (bio) organic and inorganic syntheses. However, direct comparison of mechanochemistry results is often very challenging. In mechanochemical synthetic protocols, ball mill setup (mechanical design and grinding vessel geometry) in addition to experimental parameters (milling frequency, duration, ball count and size) vary broadly. This fact poses a severe issue to further progress in this exciting research area because ball mill setup and experimental parameters govern how much kinetic energy is transferred to a chemical reaction. In this work, we address the challenge of comparing mechanochemical reaction results by taking the energy dose provided by ball mills as a unified metric into account. In this quest, we applied kinematic modeling to two ball mills functioning under distinct working principles to express the energy dose as a mathematical function of the experimental parameters. By examining the effect of energy dose on the extent of the mechanocatalytic depolymerization (MCD) of lignocellulosic biomass (beechwood), we found linear correlations between yield of water-soluble products (WSP) and energy dose for both ball mills. Interestingly, when a substrate layer is formed on the grinding jar wall and/or grinding medium, a weak non-linear correlation between water-soluble products yield and energy dose is identified. We demonstrate that the chemical reaction’s best utilization of kinetic energy is achieved in the linear regime, which presents improved WSP yields for given energy doses. In the broader context, the current analysis outlines the usefulness of the energy dose as a unified metric in mechanochemistry to further the understanding of reaction results obtained from different ball mills operating under varied experimental conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetic Energy Dose as a Unified Metric for Comparing Ball Mills in the Mechanocatalytic Depolymerization of Lignocellulose

Keßler

Rinaldi

2022

Front. Chem.

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“…It is considered that conformational change of the glucoside rings caused by mechanical constraints is the key step for the dry acidcatalyzed hydrolysis of the 1,4-β-glycosidic bonds. 25 The acid amount might affect the depolymerization degree of bamboo powder, which would further impact the conversion and yield of sugar alcohols. Thus, the effect of the acid amount on the catalytic conversion of bamboo powder into sugar alcohols was investigated (Table 2).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Highly Efficient Synthesis of C5/C6 Sugar Alcohols from Bamboo Enabled by Mechanocatalytic Depolymerization

Zhao

Chen

Liu

et al. 2021

ACS Sustainable Chem. Eng.

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The exploitation of an efficient method for direct conversion of lignocellulosic biomass into various high valuable chemicals remains a huge challenge in the chemical industry. Here, mechanocatalytic depolymerization in the presence of H 2 SO 4 combined with hydrogenation with Ru/C was used to produce C5/C6 sugar alcohols starting from bamboo, which are important platform chemicals. A high yield of C5/C6 sugar alcohols was obtained, up to 91.9%, under optimal reaction conditions. The pretreatment improved the conversion and yield of the desired products by effective depolymerization of bamboo into oligosaccharides through "dry" acid-catalyzed hydrolysis of 1,4-β-glycosidic bonds. It was found that the state of Ru species significantly influenced the activity of the Ru/C catalyst. The Ru/C catalyst containing Ru and RuO 2 species with the RuO 2 /Ru ratio of 0.56−1.44 exhibited high catalytic activity in the transformation of bamboo into C5/C6 sugar alcohols. This work provided an effective and potential route to utilize bamboo processing residues to produce high-valued chemicals.

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“…[12] Pioneering work has demonstrated the application of mechanochemical activation of cellulose to obtain oligosaccharides, [13] sugar alcohols, [14] and furfurals [15] with high yield [16][17][18] in astonishingly mild conditions. The underlying reasons for the enormous mechanochemical rate accelerations seen for cellulose, [19] as well as a protein mimic in recent force-clamp-mode atomic force microscopy (AFM) experiments, [20] have been probed recently to generate further insight in the burgeoning field of biomass mechanochemistry.…”

Section: Introductionmentioning

confidence: 99%

Improving the Yield and Rate of Acid‐Catalyzed Deconstruction of Lignin by Mechanochemical Activation

2020

Self Cite

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Lignin is a potential biomass feedstock from plant material, but it is particularly difficult to economically process. Inspired by recent ball‐milling results, state‐of‐the‐art quantum mechanochemistry calculations have been performed to isolate and probe the purely mechanochemical stretching effect alone upon acid‐catalyzed deconstruction of lignin. Effects upon cleavage of several exemplary simple ethers are examined first, and with low stretching force they all are predicted to cleave substantially faster, allowing for use of milder acids and lower temperatures. Effects upon an experimentally known lignin fragment model (containing the ubiquitous β‐O‐4 linkage) are next examined; this first required a mechanism refinement (3‐step indirect cleavage, 1‐step side reaction) and identification of the rate‐limiting step under zero‐force (thermal) conditions. Mechanochemical activation using very low stretching forces improves at first only yield, by fully shutting off the ring‐closure side reaction. At only somewhat larger forces, in stark contrast, a switch in mechanism is found to occur, from 3‐step indirect cleavage to the direct cleavage mechanism of simple ethers, finally strongly enhancing the cleavage rate of lignin. It is concluded that mechanochemical activation of the common β‐O‐4 link in lignin would improve the rate of its acidolysis via a mechanism switch past a low force threshold. Relevance to ball‐milling experiments is discussed.

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Understanding the Mechanocatalytic Conversion of Biomass: A Low‐Energy One‐Step Reaction Mechanism by Applying Mechanical Force

Abstract: Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Cited by 27 publications

References 47 publications

Kinetic Energy Dose as a Unified Metric for Comparing Ball Mills in the Mechanocatalytic Depolymerization of Lignocellulose

Kinetic Energy Dose as a Unified Metric for Comparing Ball Mills in the Mechanocatalytic Depolymerization of Lignocellulose

Highly Efficient Synthesis of C5/C6 Sugar Alcohols from Bamboo Enabled by Mechanocatalytic Depolymerization

Improving the Yield and Rate of Acid‐Catalyzed Deconstruction of Lignin by Mechanochemical Activation

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