scholarly journals Supported-Metal Catalysts in Upgrading Lignin to Aromatics by Oxidative Depolymerization

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 467
Author(s):  
Cédric Cabral Almada ◽  
Aleksandr Kazachenko ◽  
Pascal Fongarland ◽  
Denilson Da Silva Perez ◽  
Boris N. Kuznetsov ◽  
...  
Keyword(s):  
Gold Catalyst ◽  
Added Value ◽  
Supported Metal Catalysts ◽  
Lignin Valorization ◽  
Mild Conditions ◽  
Platinum Particles ◽  
Lignin Oxidation ◽  
Target Molecules ◽  
Supported Gold ◽  
Lignin Depolymerization

Supported gold and platinum particles on titanium oxide catalysts were evaluated in the oxidative depolymerization of lignins toward high added value aromatics under mild conditions (T: 150 °C, Pair: 20 bar, CNaOH: 10 g/L, 1 h). Kraft and ethanol Organosolv lignins were engaged in the study. Gold catalyst showed a strong tendency to further oxidize aromatics produced from lignin depolymerization to volatile compounds leading to very low yield in target molecules. On the contrary, platinum-based catalysts were allowed to observe enhanced yields that were attributed to its ability to preserve lignin’s substructure during the reaction. A kinetic model was constructed based on the results observed, which allowed us to identify the occurrence of condensation reactions during lignin oxidation and degradation of the produced aromatic compounds as the main limitations to reach high product yields. Insights on lignin oxidation and the catalyst’s role lead through this study would help to reach higher control over lignin valorization.

scholarly journals Added-Value Chemicals from Lignin Oxidation

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4602
Author(s):  
Carina A. Esteves Costa ◽  
Carlos A. Vega-Aguilar ◽  
Alírio E. Rodrigues
Keyword(s):  
Dicarboxylic Acids ◽  
Added Value ◽  
Comprehensive Overview ◽  
Lignin Valorization ◽  
Cooking Process ◽  
Lignin Oxidation ◽  
H2o2 Oxidation ◽  
Pulp And Paper Industries ◽  
Energy Strategies ◽  
Different Sources

Lignin is the second most abundant component, next to cellulose, in lignocellulosic biomass. Large amounts of this polymer are produced annually in the pulp and paper industries as a coproduct from the cooking process—most of it burned as fuel for energy. Strategies regarding lignin valorization have attracted significant attention over the recent decades due to lignin’s aromatic structure. Oxidative depolymerization allows converting lignin into added-value compounds, as phenolic monomers and/or dicarboxylic acids, which could be an excellent alternative to aromatic petrochemicals. However, the major challenge is to enhance the reactivity and selectivity of the lignin structure towards depolymerization and prevent condensation reactions. This review includes a comprehensive overview of the main contributions of lignin valorization through oxidative depolymerization to produce added-value compounds (vanillin and syringaldehyde) that have been developed over the recent decades in the LSRE group. An evaluation of the valuable products obtained from oxidation in an alkaline medium with oxygen of lignins and liquors from different sources and delignification processes is also provided. A review of C4 dicarboxylic acids obtained from lignin oxidation is also included, emphasizing catalytic conversion by O2 or H2O2 oxidation.

scholarly journals Catalytic Performance of Gold Supported on Mn, Fe and Ni Doped Ceria in the Preferential Oxidation of CO in H2-Rich Stream

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 469 ◽  
Author(s):  
Shuna Li ◽  
Huaqing Zhu ◽  
Zhangfeng Qin ◽  
Yagang Zhang ◽  
Guofu Wang ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Gold Catalyst ◽  
Gold Catalysts ◽  
Catalytic Performance ◽  
Supported Metal Catalysts ◽  
Doped Ceria ◽  
Preferential Oxidation ◽  
Metal Support Interaction ◽  
Ceria Support ◽  
Supported Gold

Ceria supported metal catalysts often exhibit high activity in the preferential oxidation (PROX) of CO in H2-rich stream and doping the ceria support with other metals proves to be rather effective in further enhancing their catalytic performance. Therefore, in this work, a series of ceria materials doped with Mn, Fe and Ni (CeM, where M = Mn, Fe and Ni; M/Ce = 1/8) were synthesized by a modified hydrothermal method; with the doped ceria materials (CeM) as the support, various supported gold catalysts (Au/CeM) were prepared by the colloidal deposition method. The influence of metal dopant on the performance of these ceria materials supported with gold catalysts in CO PROX was then investigated in detail with the help of various characterization measures such as N2 sorption, XRD, TEM, Raman spectroscopy, H2-TPR, XPS and XAS. The results indicate that the incorporation of Mn, Fe and Ni metal ions into ceria can remarkably increase the amount of oxygen vacancies in the doped ceria support, which is beneficial for enhancing the reducibility of ceria, the metal-support interaction and the dispersion of gold species. Although the gold catalysts supported on various doped ceria are similar in the size and state of Au nanoparticles, the CO conversions for CO PROX over Au/CeMn, Au/CeFe and Au/CeNi catalysts are 65.6%, 93.0% and 48.2%, respectively, much higher than the value of 33.6% over the undoped Au/CeO2 catalyst at ambient temperature. For CO PROX over the Au/CeNi catalyst, the conversion of CO remains near 100% at 60–130 °C, with a PROX selectivity to CO2 of higher than 50%. The excellent performance of Au/CeNi catalyst can be ascribed to its large amount of oxygen vacancies and high reducibility on account of Ni incorporation. The insight shown in this work helps to clarify the doping effect of other metals on the physicochemical properties of ceria, which is then beneficial to building a structure-performance relation for ceria supported gold catalyst as well as developing a better catalyst for removing trace CO in the hydrogen stream and producing high purity hydrogen.

scholarly journals Selective oxidation of uronic acids into aldaric acids over gold catalyst

RSC Advances ◽  
2015 ◽  
Vol 5 (25) ◽  
pp. 19502-19507 ◽  
Author(s):  
Sari Rautiainen ◽  
Petra Lehtinen ◽  
Jingjing Chen ◽  
Marko Vehkamäki ◽  
Klaus Niemelä ◽  
...  
Keyword(s):  
Selective Oxidation ◽  
Building Block ◽  
Gold Catalyst ◽  
Uronic Acids ◽  
Mild Conditions ◽  
Aldaric Acids

Uronic acids available from hemicelluloses were oxidized into aldaric acids, valuable building block chemicals. Au/Al2O3 oxidized glucuronic and galacturonic acids quantitatively to the corresponding glucaric and galactaric acids at mild conditions.

scholarly journals Gold-catalyzed reaction of oxabicyclic alkenes with electron-deficient terminal alkynes to produce acrylate derivatives

2013 ◽  
Vol 9 ◽  
pp. 1969-1976 ◽  
Author(s):  
Yin-wei Sun ◽  
Qin Xu ◽  
Min Shi
Keyword(s):  
Gold Catalyst ◽  
Addition Product ◽  
Terminal Alkynes ◽  
Mild Conditions ◽  
Ethynyl Ketone ◽  
Oxabicyclic Alkenes

Oxabicyclic alkenes can react with electron-deficient terminal alkynes in the presence of a gold catalyst under mild conditions, affording the corresponding addition products in moderate yields. When using alkynyl esters as substrates, the (Z)-acrylate derivatives are obtained. Using but-3-yn-2-one (ethynyl ketone) as a substrate, the corresponding addition product is obtained with (E)-configuration. The proposed mechanism of these reactions is also discussed.

Photochemical Preparation of Anatase Titania Supported Gold Catalyst for Ethanol Synthesis from CO2 Hydrogenation

2017 ◽  
Vol 148 (1) ◽  
pp. 11-22 ◽  
Author(s):  
Dong Wang ◽  
Qingyuan Bi ◽  
Guoheng Yin ◽  
Peng Wang ◽  
Fuqiang Huang ◽  
...  
Keyword(s):  
Gold Catalyst ◽  
Co2 Hydrogenation ◽  
Anatase Titania ◽  
Supported Gold ◽  
Ethanol Synthesis

Preparation of Highly Dispersive Supported Gold Catalyst by Microbial Reduction Method

1998 ◽  
Vol 14 (09) ◽  
pp. 769-771
Author(s):  
Fu Jin-Kun ◽  
◽  
Liu Yue-Ying ◽  
Hu Rong-Zong ◽  
Zeng Jin-Long ◽  
...  
Keyword(s):  
Reduction Method ◽  
Gold Catalyst ◽  
Microbial Reduction ◽  
Supported Gold

scholarly journals Ultrastable Au nanoparticles on titania through an encapsulation strategy under oxidative atmosphere

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Shaofeng Liu ◽  
Wei Xu ◽  
Yiming Niu ◽  
Bingsen Zhang ◽  
Lirong Zheng ◽  
...  
Keyword(s):  
Au Nanoparticles ◽  
Gold Catalyst ◽  
Au Catalyst ◽  
Supported Gold Catalysts ◽  
Metal Support Interaction ◽  
Excellent Activity ◽  
Metal Support ◽  
Oxidative Atmosphere ◽  
Supported Gold ◽  
Special Strategy

AbstractSupported gold catalysts play a crucial role in the chemical industry; however, their poor on-stream stability because of the sintering of the gold nanoparticles restricts their practical application. The strong metal-support interaction (SMSI), an important concept in heterogeneous catalysis, may be applied to construct the structure of catalysts and, hence, improve their reactivity and stability. Here we report an ultrastable Au nanocatalyst after calcination at 800 °C, in which Au nanoparticles are encapsulated by a permeable TiOx thin layer induced by melamine under oxidative atmosphere. Owning to the formed TiOx overlayer, the resulting Au catalyst is resistant to sintering and exhibits excellent activity and stability for catalytic CO oxidation. Furthermore, this special strategy can be extended to colloidal Au nanoparticles supported on TiO2 and commercial gold catalyst denoted as RR2Ti, providing a universal way to engineer and develop highly stable supported Au catalysts with tunable activity.

scholarly journals Melt Stable Functionalized Organosolv and Kraft Lignin Thermoplastic

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1108
Author(s):  
Shubhankar Bhattacharyya ◽  
Leonidas Matsakas ◽  
Ulrika Rova ◽  
Paul Christakopoulos
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Kraft Lignin ◽  
Added Value ◽  
Lignin Valorization ◽  
1H Nuclear Magnetic Resonance ◽  
Ft Ir ◽  
Viable Biomass

A shift towards an economically viable biomass biorefinery concept requires the use of all biomass fractions (cellulose, hemicellulose, and lignin) for the production of high added-value products. As lignin is often underutilized, the establishment of lignin valorization routes is highly important. In-house produced organosolv as well as commercial Kraft lignin were used in this study. The aim of the current work was to make a comparative study of thermoplastic biomaterials from two different types of lignins. Native lignins were alkylate with two different alkyl iodides to produce ether-functionalized lignins. Successful etherification was verified by FT-IR spectroscopy, changes in the molecular weight of lignin, as well as 13C and 1H Nuclear Magnetic Resonance (NMR). The thermal stability of etherified lignin samples was considerably improved with the T2% of organosolv to increase from 143 °C to up to 213 °C and of Kraft lignin from 133 °C to up to 168 °C, and glass transition temperature was observed. The present study shows that etherification of both organosolv and Kraft lignin with alkyl halides can produce lignin thermoplastic biomaterials with low glass transition temperature. The length of the alkyl chain affects thermal stability as well as other thermal properties.

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