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 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 and Selective Ni/CeO2–Al2O3 and Pd–Ni/CeO2–Al2O3 Catalysts for Oxy-Steam Reforming of Methanol

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 380 ◽  
Author(s):  
Pawel Mierczynski ◽  
Agnieszka Mierczynska ◽  
Radoslaw Ciesielski ◽  
Magdalena Mosinska ◽  
Magdalena Nowosielska ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Photoelectron Spectroscopy ◽  
Supported Catalysts ◽  
Energy Dispersive Spectrometer ◽  
Nickel Catalysts ◽  
Impregnation Method ◽  
Catalytic Systems ◽  
X Ray ◽  
Steam Reforming Of Methanol ◽  
Temperature Programmed

Herein, we report monometallic Ni and bimetallic Pd–Ni catalysts supported on CeO2–Al2O3 binary oxide which are highly active and selective in oxy-steam reforming of methanol (OSRM). Monometallic and bimetallic supported catalysts were prepared by an impregnation method. The physicochemical properties of the catalytic systems were investigated using a range of methods such as: Brunauer–Emmett–Teller (BET), X-ray Powder Diffraction (XRD), Temperature-programmed reduction (TPR–H2), Temperature-programmed desorption (TPD–NH3), X-ray photoelectron spectroscopy (XPS) and Scanning Electron Microscope equipped with an energy dispersive spectrometer (SEM–EDS). We demonstrate that the addition of palladium facilitates the reduction of nickel catalysts. The activity tests performed for all catalysts confirmed the promotion effect of palladium on the catalytic activity of nickel catalyst and their selectivity towards hydrogen production. Both nickel and bimetallic palladium–nickel supported catalysts showed excellent stability during the reaction. The reported catalytic systems are valuable to make advances in the field of fuel cell technology.

scholarly journals Influence of Nickel Loading on Reduced Graphene Oxide-Based Nickel Catalysts for the Hydrogenation of Carbon Dioxide to Methane

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 471
Author(s):  
Nur Diyan Mohd Ridzuan ◽  
Maizatul Shima Shaharun ◽  
Kah Mun Lee ◽  
Israf Ud Din ◽  
Poppy Puspitasari
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
High Surface ◽  
Nickel Catalysts ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Co2 Methanation ◽  
X Ray ◽  
Reduced Graphene ◽  
Temperature Programmed

In this study, a series of novel nickel catalysts supported on reduced graphene oxide nanosheets (Ni/rGO) with Ni loadings of 10, 15 and 20 wt% were successfully synthesized via the incipient wetness impregnation method. The physicochemical properties of the catalysts and rGO support were thoroughly characterized by thermogravimetric analyser, X-ray diffraction, fourier-transform infrared spectroscopy, Raman spectroscopy, N2 adsorption-desorption, temperature programmed reduction, temperature programmed CO2 desorption and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy. The properties of the catalysts are correlated to its catalytic activity for CO2 methanation which were investigated using three-phase slurry reactor at low temperature and pressure of 240 °C and 10 bar, respectively. Among the three catalysts of different Ni loading, Ni15/rGO shows the highest activity of 51% conversion of CO2 with total selectivity towards CH4. N2-physisorption and CO2-TPD analysis suggest that high catalytic performance of Ni15/rGO is attributed to the high surface area, strong basic sites and special support effect of rGO in anchoring the active metal.

scholarly journals Tuning Selectivity of Maleic Anhydride Hydrogenation Reaction over Ni/Sc-Doped ZrO2 Catalysts

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 366 ◽  
Author(s):  
Lili Zhao ◽  
Yin Zhang ◽  
Tianjie Wu ◽  
Min Zhao ◽  
Yongzhao Wang ◽  
...  
Keyword(s):  
Maleic Anhydride ◽  
Surface Structure ◽  
Selective Hydrogenation ◽  
Succinic Anhydride ◽  
Nickel Catalysts ◽  
Impregnation Method ◽  
Hydrogenation Activity ◽  
Supported Nickel Catalysts ◽  
Zro2 Catalyst ◽  
Temperature Programmed

A series of Sc-doped ZrO2 supports, with Sc2O3 content in the range of 0 to 7.5% (mol/mol), were prepared using the hydrothermal method. Ni/Sc-doped ZrO2 catalysts with nickel loading of 10% (w/w) were prepared using impregnation method, and characterized with the use of XRD, Raman, H2 temperature-programmed reduction (H2-TPR), H2 temperature-programmed desorption (H2-TPD), XPS, and in situ FT-IR techniques. The catalytic performances of Ni/Sc-doped ZrO2 catalysts in maleic anhydride hydrogenation were tested. The results showed that the introduction of Sc3+ into ZrO2 support could effectively manipulate the distribution of maleic anhydride hydrogenation products. γ-butyrolactone was the major hydrogenation product over Sc-free Ni/ZrO2 catalyst with selectivity as high as 65.8% at 210 °C and 5 MPa of H2 pressure. The Ni/Sc-doped ZrO2 catalyst, with 7.5 mol% of Sc2O3 content, selectively catalyzed maleic anhydride hydrogenation to succinic anhydride, the selectivity towards succinic anhydride was up to 97.6% under the same reaction condition. The results of the catalysts’ structure–activity relationships revealed that there was an interdependence between the surface structure of ZrO2-based support and the C=O hydrogenation performance of the ZrO2-based supported nickel catalysts. By controlling the Sc2O3 content, the surface structure of ZrO2-based support could be regulated effectively. The different surface structure of ZrO2-based supports, resulted in the different degree of interaction between the nickel species and ZrO2-based supports; furthermore, the different interaction led to the different surface oxygen vacancies electron properties of ZrO2-based supported nickel catalysts and the C=O hydrogenation activity of the catalyst. This result provides new insight into the effect of ZrO2 support on the selective hydrogenation activity of ZrO2-supported metal catalysts and contributes to the design of selective hydrogenation catalysts for other unsaturated carbonyl compounds.

scholarly journals Ethanol Dehydrogenation to Acetaldehyde over Activated Carbons-Derived from Coffee Residue

2019 ◽  
Vol 14 (2) ◽  
pp. 268 ◽  
Author(s):  
Jeerati Ob-eye ◽  
Piyasan Praserthdam ◽  
Bunjerd Jongsomjit
Keyword(s):  
Catalytic Activity ◽  
Activated Carbon ◽  
Activated Carbons ◽  
Ethanol Conversion ◽  
Physical Activation ◽  
Catalytic Dehydrogenation ◽  
X Ray ◽  
Coffee Ground ◽  
Carbon Catalysts ◽  
Dehydrogenation Of Ethanol

This study focuses on the production of acetaldehyde from ethanol by catalytic dehydrogenation using activated carbon catalysts derived from coffee ground residues and commercial activated carbon catalyst. For the synthesis of activated carbon catalysts, coffee ground residues were chemical activated with ZnCl2 (ratio 1:3) followed by different physical activation. All prepared catalysts were characterized with various techniques such as nitrogen physisorption (BET and BJH methods), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), temperature programmed desorption (CO2-TPD and NH3-TPD), X-ray Difraction (XRD), Fourier transform infrared spectrometer (FT-IR), and thermogravimetric analysis (TGA). The dehydrogenation of vaporized ethanol was performed to test the catalytic activity and product distribution. Testing catalytic activity by operated in a fixed-bed continuous flow micro-reactor at temperatures ranged from 250 to 400 °C. It was found that the AC-D catalyst (using calcination under carbon dioxide flow at 600 °C, 4 hours for physical activation) exhibited the highest catalytic activity, while all catalysts show high selectivity to acetaldehyde (more than 90%). Ethanol conversion apparently increased with increased reaction temperature. At 400 ºC, the AC-D catalyst gave the highest ethanol conversion of 47.9% and yielded 46.8% of acetaldehyde. The highest activity obtained from AC-D catalyst can be related to both Lewis acidity and Lewis basicity because the dehydrogenation of ethanol uses both Lewis acid and Lewis basic sites for this reaction. To investigate the stability of catalyst, the AC-D catalyst showed quite constant ethanol conversion for 10 h. Therefore, the synthesized activated carbon from coffee ground residues is promising to be used in dehydrogenation of ethanol. Copyright © 2019 BCREC Group. All rights reserved 

Desulfurization of Simulated Coking Benzene on Modified Activated Clay

2012 ◽  
Vol 524-527 ◽  
pp. 876-882 ◽  
Author(s):  
Chun Guang Pan ◽  
Hong Zhu Ma
Keyword(s):  
Removal Efficiency ◽  
Atmospheric Pressure ◽  
Catalytic Properties ◽  
Temperature Programmed Desorption ◽  
Acid Strength ◽  
Energy Dispersive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Temperature Programmed

Two catalysts, SO42-/activated clay (SAC) and SO42-/Fe2O3 activated clay (SFAC) were obtained by activated clay with or without Fe2O3 loading then treated with H2SO4. The acidity of the catalysts were measured by temperature-programmed desorption of ammonia (NH3-TPD), and the results confirm that the SFAC catalyst has higher acid strength than SAC catalyst. Other techniques such as X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and energy dispersive X-ray spectroscopy (EDXS) were also employed to characterize the structure of catalysts. Its catalytic properties in desulfurization reaction from the simulated coking benzene by alkylation method was also investigated under mild conditions (353 K and atmospheric pressure), the thiophene removal efficiency can reach 42% for SAC catalyst and 99% for SFAC catalyst, respectively.

scholarly journals Hydrodechlorination of CHClF2 (HCFC-22) over Pd–Pt Catalysts Supported on Thermally Modified Activated Carbon

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1291
Author(s):  
Monika Radlik ◽  
Wojciech Juszczyk ◽  
Krzysztof Matus ◽  
Wioletta Raróg-Pilecka ◽  
Zbigniew Karpiński
Keyword(s):  
Activated Carbon ◽  
Photoelectron Spectroscopy ◽  
Pt Nanoparticles ◽  
Pt Catalysts ◽  
Metal Chlorides ◽  
X Ray ◽  
Monometallic Catalysts ◽  
Scanning Transmission ◽  
Pt Alloy ◽  
Temperature Programmed

Commercial activated carbon, pretreated in helium at 1600 °C and largely free of micropores, was used as a support for two series of 2 wt.% Pd–Pt catalysts, prepared by impregnating the support with metal acetylacetonates or metal chlorides. The catalysts were characterized by temperature-programmed methods, H2 chemisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM) with energy dispersive spectroscopy (EDS). Overall, the results confirmed the existence of well-dispersed Pd–Pt nanoparticles in the bimetallic catalysts, ranging in size from 2 to 3 nm. The catalysts were investigated in the gas phase hydrodechlorination of chlorodifluoromethane (HCFC-22). In this environmentally relevant reaction, both the ex-chloride and ex-acetylacetonate Pd–Pt/C catalysts exhibited better hydrodechlorination activity than the monometallic catalysts, which is consistent with the previous results of hydrodechlorination for other chlorine-containing compounds. This synergistic effect can be attributed to the electron charge transfer from platinum to palladium. In general, product selectivity changes regularly with Pd–Pt alloy composition, from high in CH2F2 for Pd/C (70–80%) to the selective formation of CH4 for Pt/C (60–70%).

scholarly journals Selective Hydrogenation of Acetylene over Pd-Mn/Al2O3 Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 624
Author(s):  
Dmitry Melnikov ◽  
Valentine Stytsenko ◽  
Elena Saveleva ◽  
Mikhail Kotelev ◽  
Valentina Lyubimenko ◽  
...  
Keyword(s):  
Temperature Treatment ◽  
Treatment Temperature ◽  
Hydrogen Chemisorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Mn Content ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared ◽  
Cyclopentadienylmanganese Tricarbonyl

Novel bimetallic Pd-Mn/Al2O3 catalysts are designed by the decomposition of cyclopentadienylmanganese tricarbonyl (cymantrene) on reduced Pd/Al2O3 in an H2 atmosphere. The peculiarities of cymantrene decomposition on palladium and, thus, the formation of bimetallic Pd-Mn catalysts are studied. The catalysts are characterized by N2 adsorption, H2 pulse chemisorption, temperature-programmed desorption of hydrogen (TPD-H2), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The modified catalysts show the changed hydrogen chemisorption properties and the absence of weakly bonded hydrogen. Using an organomanganese precursor provides an uniform Mn distribution on the catalyst surface. Tested in hydrogenation of acetylene, the catalysts show both higher activity and selectivity to ethylene (20% higher) compared to the non-modified Pd/Al2O3 catalyst. The influence of the addition of Mn and temperature treatment on catalyst performance is studied. The optimal Mn content and treatment temperature are found. It is established that modification with Mn changes the route of acetylene hydrogenation from a consecutive scheme for Pd/Al2O3 to parallel one for the Pd-Mn samples. The reaction rate shows zero overall order by reagents for all tested catalysts.

scholarly journals Mg-Ni supported on perlite as hydrogenation catalyst: Influence of Mg and Ni content

2019 ◽  
Vol 25 (2) ◽  
pp. 193-206
Author(s):  
Vojkan Radonjic ◽  
Jugoslav Krstic ◽  
Davor Loncarevic ◽  
Nikola Vukelic ◽  
Dusan Jovanovic
Keyword(s):  
Sunflower Oil ◽  
Catalyst Activity ◽  
Nickel Catalysts ◽  
Hydrogenation Reaction ◽  
Hydrogen Chemisorption ◽  
Partial Hydrogenation ◽  
Dispersion Degree ◽  
Supported Precursors ◽  
Temperature Programmed ◽  
Mg Content

Use of broken honeycomb-like expanded perlite as support for magnesium modified nickel catalysts in process of partial hydrogenation of sunflower oil was studied. By the use of the precipitation-deposition method, two groups of precursors were synthesized: different Ni/SiO2 mole ratios with constant Mg/Ni mole ratio 0.1, and different Mg/Ni mole ratios with constant Ni/SiO2 mole ratio 0.25. Characterizations of precursors were done (scanning electron microscopy, diffuse reflectance UV?Vis, infrared spectroscopy, N2-physisorption, temperature programmed reduction (TPR) and He-pycnometry) to determine the material differences, considering the change in morphology, structure, texture and reducibility with overall Ni and Mg content. In addition, TPR and hydrogen chemisorption were performed in order to estimate the temperature reduction range of supported precursors and the dispersion degree of nickel in reduced precursors, respectively. The interaction between Ni2+ and perlite support was established. Different reducibility and dispersion were obtained as a function of Ni/SiO2 and Mg/Ni mole ratios. After the precursor?s reduction and paraffin oil impregnation, the obtained catalysts were tested in a sunflower oil hydrogenation reaction. Catalyst activity was monitored through the decrease of the refractive index and hydrogen consumption that gave the insight that the influence on catalyst activity represents the accessibility of triacylglycerols and not always the hydrogen determined dispersion degree.

Interactions of Ge Atoms with High- ê Oxide Dielectric Surfaces

2005 ◽  
Vol 879 ◽  
Author(s):  
Scott K. Stanley ◽  
John G. Ekerdt
Keyword(s):  
Oxide Layer ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Tungsten Filament ◽  
X Ray ◽  
Dielectric Surfaces ◽  
Temperature Programmed ◽  
The Stability ◽  
Ge Nanocrystals

AbstractGe is deposited on HfO2 surfaces by chemical vapor deposition (CVD) with GeH4. 0.7-1.0 ML GeHx (x = 0-3) is deposited by thermally cracking GeH4 on a hot tungsten filament. Ge oxidation and bonding are studied at 300-1000 K with X-ray photoelectron spectroscopy (XPS). Ge, GeH, GeO, and GeO2 desorption are measured with temperature programmed desorption (TPD) at 400-1000 K. Ge initially reacts with the dielectric forming an oxide layer followed by Ge deposition and formation of nanocrystals in CVD at 870 K. 0.7-1.0 ML GeHx deposited by cracking rapidly forms a contacting oxide layer on HfO2 that is stable from 300-800 K. Ge is fully removed from the HfO2 surface after annealing to 1000 K. These results help explain the stability of Ge nanocrystals in contact with HfO2.

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