Zirconium-doped enhanced the biomass hydrodeoxygenation over extremely low-loaded Pd catalysts

Abstract: Microwave (MW)-assistance may be a powerful tool also in the Hirao P–C coupling reactions of vinyl/aryl halides with dialkyl phosphites in the presence of Pd-catalysts/P-ligands elaborated forty years ago. This review surveys the development of this reaction by showing the expansion of the reagents and catalysts, as well as the information accumulated. The stress was laid on the “green” aspects, the simplification of the catalyst systems, and the reliable mechanistic details in order to be able to establish the optimum conditions. The best protocol involves the use of some excess of the >P(O)H reagent to ensure the PdII→Pd0 reduction and, via its trivalent tautomeric form (>POH) also the P-ligand. The overall rate is the result of two factors, the activity of the catalyst complex formed, and the reactivity of the reactants in the P–C coupling reactions. Both components are influenced by the nature of the aryl substituents in Ar2P(O)H. NiII salts may also be used as the catalyst precursor, however, despite the PdII→Pd0→PdII route, in this case, a NiII→NiIV→NiII sequence was proved.

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Palladium Promoted Copolymerization of Carbon Monoxide with Polar or Nonpolar Olefinic Monomers

Current Organic Chemistry ◽

10.2174/1385272824999201102221113 ◽

2020 ◽

Vol 24 ◽

Author(s):

Yanlin Zong ◽

Qiankun Li ◽

Hongliang Mu ◽

Zhongbao Jian

Keyword(s):

Carbon Monoxide ◽

Physical Properties ◽

Vinyl Monomers ◽

Pd Catalysts ◽

Catalytic Systems

Abstract:: The copolymers of carbon monoxide (CO) and olefins, namely polyketones, are a family of widely used materi-als. In the catalytic preparation of these materials, palladium(II) catalysts represent the most successful catalytic systems. The production of both alternating and non-alternating polyketones has been achieved, with great difference in their physical properties. Herein, a variety of palladium(II) catalysts employed for the copolymerization of CO with various olefinic mon-omers such as ethylene, α-olefins, styrene and polar vinyl monomers are fully summarized. The influence of important fac-tors such as solvents and counterions on specific copolymerization, is also discussed. This review aims to enlighten the de-sign of new Pd catalysts with improved properties, as well as the development of new polyketone materials.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19872019 ◽

1987 ◽

Vol 52 (8) ◽

pp. 2019-2027 ◽

Cited By ~ 1

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.

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Highly Efficient Reductive Catalytic Fractionation of Lignocellulosic Biomass over Extremely Low-Loaded Pd Catalysts

ACS Catalysis ◽

10.1021/acscatal.0c03393 ◽

2020 ◽

Vol 10 (21) ◽

pp. 12487-12506

Author(s):

Jaeyong Park ◽

Handi Setiadi Cahyadi ◽

Umair Mushtaq ◽

Deepak Verma ◽

Daseul Han ◽

...

Keyword(s):

Lignocellulosic Biomass ◽

Pd Catalysts ◽

Highly Efficient

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

Materials for Renewable and Sustainable Energy ◽

10.1007/s40243-020-00187-1 ◽

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

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Reaction pathways for the HDO of guaiacol over supported Pd catalysts: Effect of support type in the deoxygenation of hydroxyl and methoxy groups

Molecular Catalysis ◽

10.1016/j.mcat.2021.111491 ◽

2021 ◽

pp. 111491

Author(s):

Camila A. Teles ◽

Priscilla M. de Souza ◽

Raimundo C. Rabelo-Neto ◽

Alejandra Teran ◽

Gary Jacobs ◽

...

Keyword(s):

Reaction Pathways ◽

Pd Catalysts ◽

Supported Pd Catalysts ◽

Methoxy Groups ◽

Effect Of Support ◽

Supported Pd

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The Activating Effect of Strong Acid for Pd-Catalyzed Directed C–H Activation by Concerted Metalation-Deprotonation Mechanism

Molecules ◽

10.3390/molecules26134083 ◽

2021 ◽

Vol 26 (13) ◽

pp. 4083

Author(s):

Heming Jiang ◽

Tian-Yu Sun

Keyword(s):

Activation Energy ◽

Dft Calculations ◽

Energy Barrier ◽

Computational Study ◽

Strong Acid ◽

Activation Energy Barrier ◽

Pd Catalysts ◽

Acid Ligand ◽

Strong Acids

A computational study on the origin of the activating effect for Pd-catalyzed directed C–H activation by the concerted metalation-deprotonation (CMD) mechanism is conducted. DFT calculations indicate that strong acids can make Pd catalysts coordinate with directing groups (DGs) of the substrates more strongly and lower the C–H activation energy barrier. For the CMD mechanism, the electrophilicity of the Pd center and the basicity of the corresponding acid ligand for deprotonating the C–H bond are vital to the overall C–H activation energy barrier. Furthermore, this rule might disclose the role of some additives for C–H activation.

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