Preparation of Silica-Supported Nickel Molybdenum Phosphides by Temperature-Programmed Reduction Technique

2007 ◽  
Vol 124-126 ◽  
pp. 1765-1768 ◽  
Author(s):  
So Yeon Lee ◽  
Yong Kul Lee ◽  
S.Ted Oyama ◽  
Seok Hee Lee ◽  
Hee Chul Woo
Keyword(s):  
Single Phase ◽  
Reduction Rate ◽  
Reduction Reaction ◽  
Molar Ratio ◽  
Infrared Spectrometry ◽  
Molybdenum Oxides ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
Ammonium Hydrogen ◽  
Temperature Programmed

Silica supported nickel molybdenum phosphides (NiMoP/SiO2) were successfully prepared by temperature-programmed reduction (TPR) reaction of phosphorous-impregnated nickel molybdenum oxides (NiMoO4) precursors with hydrogen at relatively low temperatures (530 – 590 oC) and characterized by Fourier transform-Infrared spectrometry (FT-IR), X-ray diffraction (XRD), Electron probe microanalysis (EPMA) and Temperature-programmed reduction reaction (TPR). The process of solid transformation and properties of materials prepared from ammonium hydrogen phosphate (AMP)-impregnated samples were compared with those of phosphide made from phosphoric acid (PAC)-impregnated samples. Results show that the formation of a single NiMoP phase on silica significantly depends on reduction rates, phosphorous sources and phosphorous loadings. A single phase of NiMoP on SiO2 was particularly promoted at a below 5 oC/min of reduction rate and the starting molar ratio of Ni/Mo/P=1/1/1. A single phase of crystalline NiMoP on silica was produced from AMP-impregnated samples, while other phases of MoP, Ni2P, or NiMoP2 were appeared from PAC-impregnated samples with loading. The new phase of NiMoP2 was occurred with increasing phosphorous loading (above Ni/Mo/P=1/1/2.5) as a result of facilitated contact on the surface between the Ni-Mo bimetallic component and the phosphorous reagent

Sol-Gel Precursors and the Oxygen Storage Capacity of PrOy-ZrO2 Materials

1997 ◽  
Vol 497 ◽  
Author(s):  
C. K. Narula ◽  
K. L. Taylor ◽  
L. P. Haack ◽  
L. F. Allard ◽  
A. Datye ◽  
...  
Keyword(s):  
Single Phase ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Fluorite Structure ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
Molar Ratio ◽  
Metal Nitrates ◽  
Temperature Programmed

ABSTRACTThe gels derived from mixtures of Pr(OiC3H7)3 and Zr(OiC3H7)4•iC3H7OH, upon hydrolysis and pyrolysis, furnish single-phase PrOy-ZrO2 materials crystallized in the fluorite structure. These materials can be coated onto high-surface-area γ-alumina powders or deposited onto dense α-alumina coupons in the form of thin films from a solution of parent alkoxides modified with 2,4-pentanedione in THF. The fluorite structure of the PrOy-ZrO2 in the films appears to be thermally stable in air up to 1200°C. Temperature-programmed-reduction (TPR) measurements show that the bulk PrOy-ZrO2 material with a Pr. Zr molar ratio of 1:1 can store and release oxygen while that with a molar ratio of 1:3 cannot.The precursors play an important role in determining phase composition of the resulting PrOy-ZrO2 material. A mixture of monoclinic and cubic or tetragonal phases was found in PrOy-ZrO2 prepared from a new single-source heterometallic alkoxide, Pr2Zr6(μ4-O)2(μ-OAc)6(μ-OiPr)10(OiPr)10, whereas a mixture of cubic and tetragonal phases was present in PrOy-ZrO2 made previously by coprecipitation from aqueous solutions of the metal nitrates.

Synthesis of Biodiesel from Castor Oil Catalyzed by Cesium Phosphotungstate with the Assistance of Microwave

2013 ◽  
Vol 291-294 ◽  
pp. 300-306 ◽  
Author(s):  
Hong Yuan ◽  
Qing Shu
Keyword(s):  
Microwave Radiation ◽  
Castor Oil ◽  
Solid Acid ◽  
Maximum Yield ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Mass Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed

Two cesium phosphotungstate-derived solid acid catalysts (Cs2.5H0.5PW12 and Cs0.5H2.5PW12) were prepared. The resulting catalysts were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption and desorption isotherm and temperature programmed desorption of ammonia(NH3-TPD). The Cs2.5H0.5PW12 and Cs0.5H2.5PW12 were respectively used to catalyze the tranesterification of castor oil and methanol for the synthesis of biodiesel with the assistance of microwave. Results shown microwave radiation can greatly enhance the transesterification process when compared with conventional heating method. Cs2.5H0.5PW12 showed better catalyst performance than Cs0.5H2.5PW12. A maximum yield of 90% was obtained from the using of 30:1 molar ratio of methanol to castor oil and 15 wt % mass ratio of catalyst to castor oil at 343 K under microwave radiation after 4h.

Reduction of Molybdenum Trioxide by Using Hydrogen

2017 ◽  
Vol 888 ◽  
pp. 404-408 ◽  
Author(s):  
Mohd Nor Latif ◽  
Alinda Samsuri ◽  
Mohamed Wahab Mohamed Hisham ◽  
Mohd Ambar Yarmo
Keyword(s):  
Molybdenum Trioxide ◽  
Reduction Step ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
Thermodynamic Consideration ◽  
Rapid Reduction ◽  
Reduction Behavior ◽  
X Ray ◽  
Intermediate Phases ◽  
Temperature Programmed

Metallic molybdenum was synthesized through reduction of molybdenum trioxide (MoO3) by using hydrogen as a reducing agent. The reduction behavior of MoO3 were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The XRD results indicate that the reduction of MoO3 proceed in two steps reduction (MoO3 → MoO2 → Mo) with formation of intermediate phases of Mo4O11 during first step of reduction. However, the TPR results showed only one broad peak that correspond to all reduction step that was merge into one peak. It seem that, increasing the temperature cause the rapid reduction that correlated with thermodynamic consideration data that show the formation of metallic molybdenum is become feasible by increasing the temperature.

Au/iron oxide catalysts: temperature programmed reduction and X-ray diffraction characterization

1999 ◽  
Vol 329 (1) ◽  
pp. 39-46 ◽  
Author(s):  
G Neri ◽  
A.M Visco ◽  
S Galvagno ◽  
A Donato ◽  
M Panzalorto
Keyword(s):  
Iron Oxide ◽  
Oxide Catalysts ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed

Synthesis of Ti3Si0.4Al0.8C1.8 Solid Solution

2008 ◽  
Vol 368-372 ◽  
pp. 995-997
Author(s):  
Cui Wei Li ◽  
Hong Xiang Zhai ◽  
Yang Zhou ◽  
Shi Bo Li ◽  
Zhi Li Zhang
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Scanning Electron Microscopy ◽  
Single Phase ◽  
Lattice Parameters ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Scanning Electron

In this study, free Ti/Si/Al/C powder mixtures with molar ratio of 3:0.4:0.8:1.8 were heated in Argon with various schedules, in order to reveal the possibility for the synthesis of Ti3Si0.4Al0.8C1.8 solid solution powder. X-ray diffraction (XRD) was used for the evaluation of phase identities of the powder after different treatments. Scanning electron microscopy (SEM) was used to observe the morphology of the Ti3Si0.4Al0.8C1.8 solid solution. XRD results showed that predominantly single phase samples of Ti3Si0.4Al0.8C1.8 was prepared after heating at 1400oC for 5 min in Argon and the lattice parameters of Ti3Si0.4Al0.8C1.8 lay between those of Ti3SiC2 and Ti3AlC2.

scholarly journals Structural and magnetic properties of mechanochemically synthesized nanosized yttrium titanate

2012 ◽  
Vol 66 (3) ◽  
pp. 309-315 ◽  
Author(s):  
Tanja Barudzija ◽  
Alexey Gusev ◽  
Dragana Jugovic ◽  
Milena Marinovic-Cincovic ◽  
Miroslav Dramicanin ◽  
...  
Keyword(s):  
Quantum Interference ◽  
Single Phase ◽  
High Energy ◽  
Argon Atmosphere ◽  
Molar Ratio ◽  
Superconducting Quantum Interference Device ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Mean ◽  
First Time

Nanosized perovskite YTiO3 with the mean crystallite size of 18 nm was synthesized for the first time by mechanochemical treatment. The mechanochemical solid state reaction between commercial Y2O3 powder and mechanochemically synthesized TiO powder in molar ratio 0.5:1 was completed for 3 h in a high-energy planetary ball mill in argon atmosphere. The heating in vacuum at 1150 ?C for 12 h transforms nanosized YTiO3 to a well-crystallized single-phase perovskite YTiO3. Both samples were characterized by X-ray diffraction (XRD) and thermogravimetric (TGA/DTA) analyses, as well as superconducting quantum interference device magnetometer (SQUID) measurements.

Preparation of Forsterite by Solid State Synthesis Process and its Dielectric Properties

2012 ◽  
Vol 534 ◽  
pp. 110-113 ◽  
Author(s):  
Fei Shi ◽  
Peng Cheng Du ◽  
Jing Xiao Liu ◽  
Ji Wei Wu ◽  
Chun Yuan Luo
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Single Phase ◽  
Raw Materials ◽  
Magnesium Carbonate ◽  
Solid State Synthesis ◽  
Molar Ratio ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
X Ray

Using basic magnesium carbonate (Mg(OH)2•4MgCO3•6H2O) and SiO2 as raw materials, forsterite (Mg2SiO4) was prepared by solid state synthesis process. The optimal process for synthesizing Mg2SiO4 was obtained by adjusting Mg/Si molar ratio and sintering temperature. The crystal phase of the obtained Mg2SiO4 powder was determined by X-ray diffraction (XRD). The results indicate that the single-phase Mg2SiO4 powder can be obtained when the mixtures with Mg/Si molar ratio of 2.05～2.01 were sintered at 1350°C for 3h in the air. The as-prepared Mg2SiO4 ceramic samples which were sintered at 1300～1360°C showed better dielectric properties with εr=7.4 and tanδ =7.5×10-4.

scholarly journals Effect of Residual Na+ on the Combustion of Methane over Co3O4 Bulk Catalysts Prepared by Precipitation

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 427 ◽  
Author(s):  
Andoni Choya ◽  
Beatriz de Rivas ◽  
Jose Gutiérrez-Ortiz ◽  
Rubén López-Fonseca
Keyword(s):  
Photoelectron Spectroscopy ◽  
Near Infrared ◽  
Diffuse Reflectance Spectroscopy ◽  
Negative Impact ◽  
Methane Combustion ◽  
Molar Ratio ◽  
Temperature Programmed Reduction ◽  
X Ray ◽  
Two Samples ◽  
Temperature Programmed

The effect of the presence of residual sodium (0.4 %wt) over a Co3O4 bulk catalyst for methane combustion was studied. Two samples, with and without residual sodium, were synthesized by precipitation and thoroughly characterised by X-ray diffraction (XRD), N2 physisorption, Wavelength Dispersive X-ray Fluorescence (WDXRF), temperature-programmed reduction with hydrogen followed by temperature-programmed reduction with oxygen (H2-TPR/O2-TPO), temperature-programmed reaction with methane (CH4-TPRe), ultraviolet–visible–near-infrared diffuse reflectance spectroscopy (UV-vis-NIR DRS), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that during calcination, a fraction of the sodium atoms initially deposited on the surface diffused and migrated into the spinel lattice, inducing a distortion that improved its textural and structural properties. However, surface sodium had an overall negative impact on the catalytic activity. It led to a reduction of surface Co3+ ions in favour of Co2+, thus ultimately decreasing the Co3+/Co2+ molar ratio (from 1.96 to 1.20) and decreasing the amount and mobility of active lattice oxygen species. As a result, the catalyst with residual sodium (T90 = 545 °C) was notably less active than its clean counterpart (T90 = 500 °C). All of this outlined the significance of a proper washing when synthesizing Co3O4 catalyst using a sodium salt as the precipitating agent.

Study of Preparation, Characterization and Temperature-Programmed Reduction of NiO-ZnO Binary Materials

2013 ◽  
Vol 664 ◽  
pp. 515-520
Author(s):  
Chih Wei Tang ◽  
Jiunn Jer Hwang ◽  
Shie Hsiung Lin ◽  
Chin Chun Chung
Keyword(s):  
Weight Percent ◽  
Precipitation Method ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Areas ◽  
Temperature Programmed ◽  
Co Precipitation ◽  
Adsorption Desorption

The NiO-ZnO binary materials had been prepared by co-precipitation method. The weight percent of nickel of NiO-ZnO materials were 5, 10 and 20; they were pretreated under air at temperature of 300, 500 and 700°C, respectively. The characterization of NiO-ZnO materials were the thermal gravity analysis(TGA), X-ray diffraction(XRD), N2 adsorption-desorption at 77K, scaning electron microscope(SEM) and temperature-programmed reduction(TPR). The results revealed that surface areas of NiO-ZnO materials order from large to small were 20NiZn(OH)x(66 m2·g-1) > 10NiZn(OH)x(34 m2·g-1) > 5NiZn(OH)x(9 m2·g-1) after being calcined at the temperature of 500°C. Further, NiO-ZnO materials had two main reductive peaks at 390-415°C and 560-657°C, respectively. In all NiO-ZnO materials, 20NiZn(OH)x-C500 material had the highest surface area and the best interaction between NiO and ZnO.

Sign in / Sign up

Export Citation Format

Share Document