scholarly journals Investigating (Pseudo)-Heterogeneous Pd-Catalysts for Kraft Lignin Depolymerization under Mild Aqueous Basic Conditions

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1311
Author(s):  
Dolorès Bourbiaux ◽  
Yu Xu ◽  
Laurence Burel ◽  
Firat Goc ◽  
Pascal Fongarland ◽  
...  
Keyword(s):  
Energy Source ◽  
Aromatic Compounds ◽  
Palladium Catalysts ◽  
Paper Industry ◽  
Kraft Lignin ◽  
Synthetic Methods ◽  
Pd Catalysts ◽  
Renewable Source ◽  
Main Components ◽  
Lignin Depolymerization

Lignin is one of the main components of lignocellulosic biomass and corresponds to the first renewable source of aromatic compounds. It is obtained as a by-product in 100 million tons per year, mainly from the paper industry, from which only 2–3% is upgraded for chemistry purposes, with the rest being used as an energy source. The richness of the functional groups in lignin makes it an attractive precursor for a wide variety of aromatic compounds. With this aim, we investigated the Pd-catalyzed depolymerization of lignin under mild oxidizing conditions (air, 150 °C, and aqueous NaOH) producing oxygenated aromatic compounds, such as vanillin, vanillic acid, and acetovanillone. Palladium catalysts were implemented following different strategies, involving nanoparticles stabilized in water, and nanoparticles were supported on TiO2. Significant conversion of lignin was observed in all cases; however, depending on the catalyst nature and the synthetic methods, differences were observed in terms of selectivity in aromatic monomers, mainly vanillin. All these aspects are discussed in detail in this report, which also provides new insights into the role that Pd-catalysts can play for the lignin depolymerization mechanism.

Model reactions for the study of hydrogenation and acidic activity of palladium catalysts

1987 ◽  
Vol 52 (8) ◽  
pp. 2019-2027 ◽  
Author(s):  
Libor Červený ◽  
Nguyen Thi Du ◽  
Ivo Paseka
Keyword(s):  
Palladium Catalysts ◽  
Styrene Oxide ◽  
Side Reactions ◽  
Pd Catalysts ◽  
Variable Parameters ◽  
Acid Properties ◽  
Liquid Phase Hydrogenation ◽  
Acid Catalysed Reactions ◽  
Different Content ◽  
Model Reactions

Palladium catalysts have been used to study the hydrogenation of 1-phenyl-2-butene-1-ol which is accompanied by several side reactions considered to be acid-catalysed. Another model reaction studied was dehydration and subsequent hydrogenation or hydrogenolysis of 1-phenyl-1,3-propanediol to 3-phenyl-1-propanol, accompanied by formation of propylbenzene. The dehydration and propylbenzene formation can be again classified as acid-catalysed reactions. Another one is methanolysis of styrene oxide taking place under conditions of liquid phase hydrogenation due to the acid properties of Pd-H systems. Hydrogenation activity of Pd catalysts was tested by hydrogenation of cyclohexene. Sixteen Pd catalysts on different supports and with different content of active component were used, their activity and selectivity was determined and the effect of variable parameters in the synthesis of these catalysts on the activity and selectivity is discussed.

scholarly journals Development of palladium catalysts modified by ruthenium and molybdenum as anode in direct ethanol fuel cell

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yonis Fornazier Filho ◽  
Ana Caroliny Carvalho da Cruz ◽  
Rolando Pedicini ◽  
José Ricardo Cezar Salgado ◽  
Priscilla Paiva Luz ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Palladium Catalysts ◽  
Carbon Support ◽  
X Ray Diffraction ◽  
Direct Ethanol Fuel Cell ◽  
Pd Catalysts ◽  
Bifunctional Mechanism ◽  
Catalytic Activities ◽  
Intrinsic Mechanism ◽  
Ternary Catalysts

AbstractPhysical and electrochemical properties of Pd catalysts combined with Ru and Mo on carbon support were investigated. To this end, Pd, Pd1.3Ru1.0, Pd3.2Ru1.3Mo1.0 and Pd1.5Ru0.8Mo1.0 were synthesized on Carbon Vulcan XC72 support by the method of thermal decomposition of polymeric precursors and then physically and electrochemically characterized. The highest reaction yields are obtained for Pd3.2Ru1.3Mo1.0/C and Pd1.5Ru0.8Mo1.0/C and, as demonstrated by thermal analysis, they also show the smallest metal/carbon ratio compared the other catalysts. XRD (X-ray Diffraction) and Raman analyses show the presence of PdO and RuO2 for the Pd/C and the Pd1.3Ru1.0/C catalysts, respectively, a fact not observed for the Pd3.2Ru1.3 Mo1.0 /C and the Pd1.5Ru0.8Mo1.0/C catalysts. The catalytic activities were tested for the ethanol oxidation in alkaline medium. Cyclic voltammetry (CV) shows Pd1.3Ru1.0/C exhibiting the highest peak of current density, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. From, chronoamperometry (CA), it is possible to observe the lowest rate of poisoning for the Pd1.3Ru1.0/C, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. These results suggested that catalytic activity of the binary and the ternary catalysts are improved in comparison with Pd/C. The presence of RuO2 activated the bifunctional mechanism and improved the catalytic activity in the Pd1.3Ru1.0/C catalyst. The addition of Mo in the catalysts enhanced the catalytic activity by the intrinsic mechanism, suggesting a synergistic effect between metals. In summary, we suggest that it is possible to synthesize ternary PdRuMo catalysts supported on Carbon Vulcan XC72, resulting in materials with lower poisoning rates and lower costs than Pd/C. Graphic abstract

The effect of protic solvents in the conversion of lignin from Earleaf Acacia tree

2021 ◽  
Vol 11 (1) ◽  
pp. 123-126
Author(s):  
Khoa Phung Thanh ◽  
Khanh Vu Bao ◽  
Phat Huynh Van ◽  
Truc Nguyen Kim ◽  
An Tran Nguyen Minh ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Solvent Polarity ◽  
Pulp Industry ◽  
Protic Solvents ◽  
Renewable Feedstock ◽  
Bulk Chemical ◽  
Paper And Pulp ◽  
Paper And Pulp Industry ◽  
Main Components ◽  
Acacia Tree

Lignin is one of main components of lignocellulosic along with cellulose and hemicellulose. It is a by-product of the paper and pulp industry, and has aromatic backbones making them an ideal renewable feedstock of aromatic compounds for a range of applications. Catalytic conversion of lignin from Earleaf Acacia tree was performed using high pressure/temperature reactor with Ru/C catalyst and protic solvents. The results showed that the conversion of lignin depends on the solvent polarity of protic solvents, and Ru/C catalyst enhanced the lignin conversion. Phenolic compounds are the main components of lignin conversion. Those compounds can be applied as a basement for bulk chemical and fuels.

scholarly journals Volatilome and Essential Oil of Ulomoides dermestoides: A Broad-Spectrum Medical Insect

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6311
Author(s):  
Paulina J. Cázares-Samaniego ◽  
Claudia G. Castillo ◽  
Miguel A. Ramos-López ◽  
Marco M. González-Chávez
Keyword(s):  
Secondary Metabolites ◽  
Essential Oil ◽  
Essential Oils ◽  
Traditional Medicine ◽  
Broad Spectrum ◽  
Alternative Treatment ◽  
Aromatic Compounds ◽  
Therapeutic Potential ◽  
Pharmacological Interest ◽  
Main Components

Ulomoides dermestoides are used as a broad-spectrum medical insect in the alternative treatment of various diseases. Preliminary volatilome studies carried out to date have shown, as the main components, methyl-1,4-benzoquinone, ethyl-1,4-benzoquinone, 1-tridecene, 1-pentadecene, and limonene. This work focused on the production of metabolites and their metabolic variations in U. dermestoides under stress conditions to provide additional valuable information to help better understand the broad-spectrum medical uses. To this end, VOCs were characterized by HS-SPME with PEG and CAR/PDMS fibers, and the first reported insect essential oils were obtained. In HS-SMPE, we found 17 terpenes, six quinones, five alkenes, and four aromatic compounds; in the essential oils, 53 terpenes, 54 carboxylic acids and derivatives, three alkynes, 12 alkenes (1-Pentadecene, EOT1: 77.6% and EOT2: 57.9%), 28 alkanes, nine alkyl disulfides, three aromatic compounds, 19 alcohols, three quinones, and 12 aldehydes were identified. Between both study approaches, a total of 171 secondary metabolites were identified with no previous report for U. dermestoides. A considerable number of the identified metabolites showed previous studies of the activity of pharmacological interest. Therefore, considering the wide variety of activities reported for these metabolites, this work allows a broader vision of the therapeutic potential of U. dermestoides in traditional medicine.

Fast methods for the identification of suitable chemo‐enzymatic treatments of Kraft lignin to obtain aromatic compounds

2020 ◽  
Vol 14 (3) ◽  
pp. 521-532 ◽  
Author(s):  
René Herrera Diaz ◽  
Laura Bodi‐Paul ◽  
Oihana Gordobil ◽  
Jalel Labidi
Keyword(s):  
Aromatic Compounds ◽  
Kraft Lignin ◽  
Fast Methods

scholarly journals Insights into the Potential of Hardwood Kraft Lignin to Be a Green Platform Material for Emergence of the Biorefinery

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1795
Author(s):  
Juliana M. Jardim ◽  
Peter W. Hart ◽  
Lucian Lucia ◽  
Hasan Jameel
Keyword(s):  
Research And Development ◽  
Polymer Blends ◽  
Carbon Fibers ◽  
Aromatic Compounds ◽  
Critical Review ◽  
Black Liquor ◽  
Kraft Lignin ◽  
Softwood Kraft Lignin ◽  
Structure Properties

Lignin is an abundant, renewable, and relatively cheap biobased feedstock that has potential in energy, chemicals, and materials. Kraft lignin, more specifically, has been used for more than 100 years as a self-sustaining energy feedstock for industry after which it has finally reached more widespread commercial appeal. Unfortunately, hardwood kraft lignin (HWKL) has been neglected over these years when compared to softwood kraft lignin (SWKL). Therefore, the present work summarizes and critically reviews the research and development (R&D) dealing specifically with HWKL. It will also cover methods for HWKL extraction from black liquor, as well as its structure, properties, fractionation, and modification. Finally, it will reveal several interesting opportunities for HWKL that include dispersants, adsorbents, antioxidants, aromatic compounds (chemicals), and additives in briquettes, pellets, hydrogels, carbon fibers and polymer blends and composites. HWKL shows great potential for all these applications, however more R&D is needed to make its utilization economically feasible and reach the levels in the commercial lignin market commensurate with SWKL. The motivation for this critical review is to galvanize further studies, especially increased understandings in the field of HWKL, and hence amplify much greater utilization.

Catalytic Asymmetric Synthesis of P-Stereogenic Phosphines: Beyond Precious Metals

Synlett ◽  
2020 ◽  
Author(s):  
David S. Glueck
Keyword(s):  
Asymmetric Synthesis ◽  
Asymmetric Catalysis ◽  
Palladium Catalysts ◽  
Precious Metals ◽  
Synthetic Methods ◽  
Secondary Phosphine ◽  
Phosphine Oxides ◽  
Chiral Epoxides ◽  
Earth Abundant ◽  
Limonene Oxide

AbstractMetal-catalyzed asymmetric synthesis of P-stereogenic phosphines is a potentially useful approach to a class of chiral ligands with valuable applications in asymmetric catalysis. We introduced this idea with chiral platinum and palladium catalysts, exploiting rapid pyramidal inversion in diastereomeric metal–phosphido complexes (ML*(PRR′)) to control phosphorus stereochemistry. This Account summarizes our attempts to develop related synthetic methods using earth-abundant metals, especially copper, in which weaker metal–ligand bonds and faster substitution processes were expected to result in more active catalysts. Indeed, precious metals were not required. Without any transition metals at all, we exploited related P-epimerization processes to prepare enantiomerically pure phosphiranes and secondary phosphine oxides (SPOs) from commercially available chiral epoxides.1 Introduction2 Copper-Catalyzed Phosphine Alkylation3 Copper-Catalyzed Tandem Phosphine Alkylation/Arylation4 Nickel-Catalyzed Phosphine Alkylation5 Proton-Mediated P-Epimerization in Synthesis of Chiral Phosphiranes6 Diastereoselective Synthesis of P-Stereogenic Secondary Phosphine Oxides (SPOs) from (+)-Limonene Oxide7 Conclusions

scholarly journals Polyurethane Synthesis from Sugarcane Bagasse Organosolv and Kraft Lignin

2015 ◽  
Vol 659 ◽  
pp. 527-532 ◽  
Author(s):  
Chularat Sakdaronnarong ◽  
Nattawee Srimarut ◽  
Navadol Laosiripojana
Keyword(s):  
Sodium Hydroxide ◽  
Sugarcane Bagasse ◽  
Paper Industry ◽  
Pulp And Paper Industry ◽  
Kraft Lignin ◽  
Single Step ◽  
Pulp And Paper ◽  
Hydrolysis Reaction ◽  
Hydroxyl Groups ◽  
Organosolv Lignin

Sugarcane bagasse (SCB) was subjected to a single-step fractionation and hydrolysis reaction in the presence of various organic solvents. The reaction was performed at 170 °C for 3 h when sodium hydroxide was used as catalyst. The results showed that suitable solvents significantly enhanced the yield of lignin fractionation and simultaneous hydrolysis reaction took place indicated by an increase of hydroxyl groups in lignin molecules. Lignin-based polyurethane (LPU) from SCB organosolv lignin polyols had relatively better mechanical and thermal resistant properties compared to LPU from liquefied Kraft lignin from pulp and paper industry.

Towards lignin consolidated bioprocessing: simultaneous lignin depolymerization and product generation by bacteria

2015 ◽  
Vol 17 (11) ◽  
pp. 4951-4967 ◽  
Author(s):  
Davinia Salvachúa ◽  
Eric M. Karp ◽  
Claire T. Nimlos ◽  
Derek R. Vardon ◽  
Gregg T. Beckham
Keyword(s):  
Aromatic Compounds ◽  
Consolidated Bioprocessing ◽  
Product Generation ◽  
Lignin Depolymerization

Lignin Consolidated Bioprocessing utilizes microbes that simultaneously depolymerize lignin and convert the resulting aromatic compounds to fuel and chemical precursors.

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