scholarly journals Metal and Precursor Effect during 1-Heptyne Selective Hydrogenation Using an Activated Carbon as Support

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Cecilia R. Lederhos ◽  
Juan M. Badano ◽  
Nicolas Carrara ◽  
Fernando Coloma-Pascual ◽  
M. Cristina Almansa ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Selective Hydrogenation ◽  
Photoelectron Spectroscopy ◽  
Palladium Catalysts ◽  
Active Sites ◽  
Ruthenium Catalysts ◽  
Superior Performance ◽  
Support Surface ◽  
Electronic Effects ◽  
X Ray

Palladium, platinum, and ruthenium supported on activated carbon were used as catalysts for the selective hydrogenation of 1-heptyne, a terminal alkyne. All catalysts were characterized by temperature programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. TPR and XPS suggest that the metal in all catalysts is reduced after the pretreatment with H2at 673 K. The TPR trace of the PdNRX catalyst shows that the support surface groups are greatly modified as a consequence of the use of HNO3during the catalyst preparation. During the hydrogenation of 1-heptyne, both palladium catalysts were more active and selective than the platinum and ruthenium catalysts. The activity order of the catalysts is as follows: PdClRX > PdNRX > PtClRX ≫ RuClRX. This superior performance of PdClRX was attributed in part to the total occupancy of the d electronic levels of the Pd metal that is supposed to promote the rupture of the H2bond during the hydrogenation reaction. The activity differences between PdClRX and PdNRX catalysts could be attributed to a better accessibility of the substrate to the active sites, as a consequence of steric and electronic effects of the superficial support groups. The order for the selectivity to 1-heptene is as follows: PdClRX = PdNRX > RuClRX > PtClRX, and it can be mainly attributed to thermodynamic effects.

scholarly journals High-Active Metallic-Activated Carbon Catalysts for Selective Hydrogenation

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Nicolás Carrara ◽  
Carolina Betti ◽  
Fernando Coloma-Pascual ◽  
María Cristina Almansa ◽  
Laura Gutierrez ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Selective Hydrogenation ◽  
Nickel Catalysts ◽  
Metallic Phase ◽  
Hydrogen Chemisorption ◽  
Electronic Effects ◽  
X Ray ◽  
Mild Conditions ◽  
Temperature Programmed ◽  
Carbon Catalysts

A series of low-loaded metallic-activated carbon catalysts were evaluated during the selective hydrogenation of a medium-chain alkyne under mild conditions. The catalysts and support were characterized by ICP, hydrogen chemisorption, Raman spectroscopy, temperature-programmed desorption (TPD), temperature-programmed reduction (TPR), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR micro-ATR), transmission electronic microscopy (TEM), and X-ray photoelectronic spectroscopy (XPS). When studying the effect of the metallic phase, the catalysts were active and selective to the alkene synthesis. NiCl/C was the most active and selective catalytic system. Besides, when the precursor salt was evaluated, PdN/C was more active and selective than PdCl/C. Meanwhile, alkyne is present in the reaction media, and geometrical and electronic effects favor alkene desorption and so avoid their overhydrogenation to the alkane. Under mild conditions, nickel catalysts are considerably more active and selective than the Lindlar catalyst.

scholarly journals Selective Hydrogenation of Naphthalene over γ-Al2O3-Supported NiCu and NiZn Bimetal Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1215 ◽  
Author(s):  
Jingqiu Li ◽  
Liu Shi ◽  
Gang Feng ◽  
Zhangping Shi ◽  
Chenglin Sun ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Density Functional ◽  
Surface Engineering ◽  
Rational Surface ◽  
Impregnation Method ◽  
X Ray ◽  
Hydrogenation Activity ◽  
Calculation Results

A series of Cu and Zn modified Ni/Al2O3 catalysts were prepared using an incipient impregnation method for the selective hydrogenation of naphthalene into tetralin. X-ray diffraction (XRD), H2-Temperature programmed reduction (H2-TPR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were applied to reveal the structure regulation, and density functional theory (DFT) calculations were performed to investigate the electronic effect and reactant adsorptions on the active sites. The results showed that the addition of CuO promoted the hydrogenation of naphthalene with an inhibited tetraline selectivity. However, a simultaneously increasing naphthalene conversion and tetraline selectivity were achieved over the Zn modified Ni/Al2O3 catalysts. The characterization and calculation results revealed that the doping of CuO improved the hydrogenation activity with a low tetralin selectivity due to the H spillover from the Cu. The addition of ZnO decreased the interaction between NiOx and Al2O3 in NiZn/Al2O3 catalysts, which efficiently increased the reduction ability of NiOx species and, thus, improved the naphthalene hydrogenation activity. The electron transfer from ZnO to NiOx weakened the adsorption of tetraline and resulted in increased tetraline selectivity. This work provides insight into developing efficient catalysts for heavy aromatics conversions via rational surface engineering.

scholarly journals Study on Adsorption Properties of Modified Corn Cob Activated Carbon for Mercury Ion

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4483
Author(s):  
Yuyingnan Liu ◽  
Xinrui Xu ◽  
Bin Qu ◽  
Xiaofeng Liu ◽  
Weiming Yi ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Photoelectron Spectroscopy ◽  
Adsorption Process ◽  
Physical Adsorption ◽  
Raw Material ◽  
Order Kinetic ◽  
Mercury Ions ◽  
Corn Cob ◽  
Adsorption Time ◽  
X Ray

In this study, corn cob was used as raw material and modified methods employing KOH and KMnO4 were used to prepare activated carbon with high adsorption capacity for mercury ions. Experiments on the effects of different influencing factors on the adsorption of mercury ions were undertaken. The results showed that when modified with KOH, the optimal adsorption time was 120 min, the optimum pH was 4; when modified with KMnO4, the optimal adsorption time was 60 min, the optimal pH was 3, and the optimal amount of adsorbent and the initial concentration were both 0.40 g/L and 100 mg/L under both modified conditions. The adsorption process conforms to the pseudo-second-order kinetic model and Langmuir model. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Zeta potential characterization results showed that the adsorption process is mainly physical adsorption, surface complexation and ion exchange.

Physical Chemistry of the Interface between Attached Micro-Organisms and Their Support

1990 ◽  
Vol 22 (1-2) ◽  
pp. 1-16 ◽  
Author(s):  
P. G. Rouxhet ◽  
N. Mozes
Keyword(s):  
Photoelectron Spectroscopy ◽  
Bacterial Adhesion ◽  
Surface Composition ◽  
Chemical Properties ◽  
Dlvo Theory ◽  
Support Surface ◽  
X Ray ◽  
Polymer Molecules ◽  
Physico Chemical ◽  
Micro Organisms

The thermodynamic approach of adhesion and DLVO theory are complementary to predict initial bacterial adhesion; the interplay between short- and long-range forces, respectively, may be due to surface roughness. Due to the influence of electrical double layer interactions, adhesion can be promoted by treatments leading to modification of the cell or support surface properties. Adhesion is influenced by cell-cell interactions, by the cpresence of polymer molecules on the surface and by the composition of the medium. X-ray photoelectron spectroscopy can be applied to determine the elemental composition of the surface of microorganisms; some information on the chemical functions can also be obtained. The surface composition is related to physico-chemical properties which play a determining role in adhesion and flocculation, in particular the hydrophobicity and the zeta potential.

scholarly journals Biomass-Derived Activated Carbon as a Catalyst for the Effective Degradation of Rhodamine B dye

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 926
Author(s):  
Shamim Ahmed Hira ◽  
Mohammad Yusuf ◽  
Dicky Annas ◽  
Hu Shi Hui ◽  
Kang Hyun Park
Keyword(s):  
Electron Microscopy ◽  
Activated Carbon ◽  
Rhodamine B ◽  
Photoelectron Spectroscopy ◽  
High Specific Surface Area ◽  
High Porosity ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Transmission Electron

Activated carbon (AC) was fabricated from carrot waste using ZnCl2 as the activating agent and calcined at 700 °C for 2 h in a tube furnace. The as-synthesized AC was characterized using Fourier-transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller analysis; the results revealed that it exhibited a high specific surface area and high porosity. Moreover, this material displayed superior catalytic activity for the degradation of toxic Rhodamine B (RhB) dye. Rate constant for the degradation of RhB was ascertained at different experimental conditions. Lastly, we used the Arrhenius equation and determined that the activation energy for the decomposition of RhB using AC was approximately 35.9 kJ mol−1, which was very low. Hopefully it will create a great platform for the degradation of other toxic dye in near future.

scholarly journals Capping Agent Effect on Pd-Supported Nanoparticles in the Hydrogenation of Furfural

Catalysts ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 11 ◽  
Author(s):  
Shahram Alijani ◽  
Sofia Capelli ◽  
Stefano Cattaneo ◽  
Marco Schiavoni ◽  
Claudio Evangelisti ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Catalytic Performance ◽  
Shielding Effect ◽  
Capping Agents ◽  
X Ray ◽  
Supported Nanoparticles ◽  
Liquid Phase Hydrogenation ◽  
Diallyldimethylammonium Chloride ◽  
Transmission Electron

The catalytic performance of a series of 1 wt % Pd/C catalysts prepared by the sol-immobilization method has been studied in the liquid-phase hydrogenation of furfural. The temperature range studied was 25–75 °C, keeping the H2 pressure constant at 5 bar. The effect of the catalyst preparation using different capping agents containing oxygen or nitrogen groups was assessed. Polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and poly (diallyldimethylammonium chloride) (PDDA) were chosen. The catalysts were characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The characterization data suggest that the different capping agents affected the initial activity of the catalysts by adjusting the available Pd surface sites, without producing a significant change in the Pd particle size. The different activity of the three catalysts followed the trend: PdPVA/C > PdPDDA/C > PdPVP/C. In terms of selectivity to furfuryl alcohol, the opposite trend has been observed: PdPVP/C > PdPDDA/C > PdPVA/C. The different reactivity has been ascribed to the different shielding effect of the three ligands used; they influence the adsorption of the reactant on Pd active sites.

scholarly journals Nitrogen-Doped Sponge Ni Fibers as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaili Zhang ◽  
Xinhui Xia ◽  
Shengjue Deng ◽  
Yu Zhong ◽  
Dong Xie ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
High Performance ◽  
Active Phase ◽  
X Ray ◽  
Highly Active ◽  
N Doping ◽  
Energy Conversion Devices

Abstract Controllable synthesis of highly active micro/nanostructured metal electrocatalysts for oxygen evolution reaction (OER) is a particularly significant and challenging target. Herein, we report a 3D porous sponge-like Ni material, prepared by a facile hydrothermal method and consisting of cross-linked micro/nanofibers, as an integrated binder-free OER electrocatalyst. To further enhance the electrocatalytic performance, an N-doping strategy is applied to obtain N-doped sponge Ni (N-SN) for the first time, via NH3 annealing. Due to the combination of the unique conductive sponge structure and N doping, the as-obtained N-SN material shows improved conductivity and a higher number of active sites, resulting in enhanced OER performance and excellent stability. Remarkably, N-SN exhibits a low overpotential of 365 mV at 100 mA cm−2 and an extremely small Tafel slope of 33 mV dec−1, as well as superior long-term stability, outperforming unmodified sponge Ni. Importantly, the combination of X-ray photoelectron spectroscopy and near-edge X-ray adsorption fine structure analyses shows that γ-NiOOH is the surface-active phase for OER. Therefore, the combination of conductive sponge structure and N-doping modification opens a new avenue for fabricating new types of high-performance electrodes with application in electrochemical energy conversion devices.

scholarly journals On the Influence of Composition and Structure of Carbon-Supported Pt-SnO2 Hetero-Clusters onto Their Electrocatalytic Activity and Durability in PEMFC

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 803 ◽  
Author(s):  
Spasov ◽  
Ivanova ◽  
Pushkarev ◽  
Pushkareva ◽  
Presnyakova ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Photoelectron Spectroscopy ◽  
Layer Structure ◽  
Polymer Electrolyte Membrane ◽  
Carbon Support ◽  
Reduction Reaction ◽  
Support Surface ◽  
Catalytic Layer ◽  
X Ray ◽  
Electrolyte Membrane

A detailed study of the structure, morphology and electrochemical properties of Pt/C and Pt/x-SnO2/C catalysts synthesized using a polyol method has been provided. A series of catalysts supported on the SnO2-modified carbon was synthesized and studied by various methods including transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical methods, and fuel cell testing. The SnO2 content varies from 5 to 40 wt %. The TEM images, XRD and XPS analysis suggested the Pt-SnO2 hetero-clusters formation. The SnO2 content of ca. 10% ensures an optimal catalytic layer structure and morphology providing uniform distribution of Pt-SnO2 clusters over the carbon support surface. Pt/10wt %-SnO2/C catalyst demonstrates increased activity and durability toward the oxygen reduction reaction (ORR) in course of accelerated stress testing due to the high stability of SnO2 and its interaction with Pt. The polymer electrolyte membrane fuel cell current–voltage performance of the Pt/10wt %-SnO2/C is comparable with those of Pt/C, however, higher durability is expected.

Pulsed Laser Deposition in a Zinc Alloy Corrosion Study

2003 ◽  
Vol 780 ◽  
Author(s):  
R. Guerrero-Penalva ◽  
M.H. Farías ◽  
L. Cota-Araiza
Keyword(s):  
Pulsed Laser Deposition ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Reactive Element ◽  
General Mechanism ◽  
Zinc Alloy ◽  
Reactive Element Effect ◽  
X Ray

AbstractA significant improvement in corrosion resistance of the protecting oxide of alloys has been observed when adding small amounts of reactive elements, such as yttrium, this effect has been called reactive element effect (REE). The general mechanism of the REE has not been determined yet. In this work, we study a growing of a yttrium oxide film and its interaction with the phases η and α that constitutes the alloy Zn-22Al-2Cu named ZinalcoTM The alloy's surface was coated by a pulsed laser deposition technique. The deposit is controlled and characterized by x-ray photoelectron spectroscopy. The mechanism by which the reactive element produce its effects in this alloy is explained by the preferential interaction among the active sites related to the zinc rich phase and enhancing aluminum movement toward the surface where it is oxidized and the protection film formed.

Mesoporous Co–B amorphous alloy films with enhanced catalytic efficiency prepared from a mixed-surfactant solution

2009 ◽  
Vol 24 (11) ◽  
pp. 3300-3307 ◽  
Author(s):  
Hui Li ◽  
Jun Liu ◽  
Haixia Yang ◽  
Hexing Li
Keyword(s):  
Amorphous Alloy ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Chemical Reduction ◽  
Surfactant Solution ◽  
Mesoporous Structure ◽  
Mixed Surfactant ◽  
Alloy Films ◽  
X Ray ◽  
Electron Micrography

Co–B films were synthesized through the solvent evaporation-assisted chemical reduction method by using a mixed-surfactant solution containing Span 40 and (1S)-(+)-10-camphorsulfonic acid. With the characterization of x-ray diffraction, selected-area electron diffraction, x-ray photoelectron spectroscopy, scanning electron micrography, and transmission electron micrography, the resulting Co–B films were identified to be amorphous alloys with mesoporous structure. The synergistic effect of two kinds of surfactants is essential for the formation of mesoporous structure. During liquid-phase cinnamaldehyde hydrogenation to cinnamyl alcohol, the mesoporous Co–B amorphous alloy films exhibited a much higher activity and better selectivity than the solid Co–B nanoparticles prepared by direct reduction of cobalt ions with borohydride. The enhanced activity is attributed to both the mesoporous and the film structure, which provides more Co active sites for the adsorption and diffusion of reactant molecules. The improved selectivity may be related to the difference in surface curvature.

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