Transformation of Methane into Synthesis Gas Using the Redox Property of Pr-Zr Mixed Oxides: Effect of Calcination Temperature

2013 ◽  
Vol 724-725 ◽  
pp. 1187-1191
Author(s):  
Yong Gang Wei ◽  
Yun Peng Du ◽  
Kong Zhai Li ◽  
Xing Zhu ◽  
Hua Wang
Keyword(s):  
Calcination Temperature ◽  
Synthesis Gas ◽  
Mixed Oxides ◽  
Structural Evolution ◽  
Temperature Stability ◽  
Phase Segregation ◽  
Oxygen Carriers ◽  
High Temperature Stability ◽  
Calcination Temperatures ◽  
Co Precipitation

Pr-Zr mixed oxides prepared by co-precipitation were used as oxygen carriers for converting methane into synthesis gas through gas-solid reactions. The structural evolution and reducibility of Pr-Zr oxygen carriers with calcination temperatures from 600 to 1200°C were investigated by XRD and TPR techniques and correlated to their activity for methane selective oxidation. The Pr-Zr mixed oxides calcined at 600-800°C show outstanding thermostability, and higher calcination temperatures result in phase segregation. Pr0.7Zr0.3O2-δ possesses high temperature stability(<900 °C) and the best appropriate calcination temperature is 800°C for methane gas-solid reaction.

scholarly journals FTIR study of hydrotalcite

2018 ◽  
Vol 11 (2) ◽  
pp. 147-156
Author(s):  
Miroslava Mališová ◽  
Michal Horňáček ◽  
Jozef Mikulec ◽  
Pavol Hudec ◽  
Vladimír Jorík
Keyword(s):  
Calcination Temperature ◽  
Spinel Structure ◽  
Ftir Analysis ◽  
Ftir Study ◽  
Calcination Temperatures ◽  
The Third ◽  
Two Samples ◽  
Co Precipitation

Abstract The aim of the research was the study of aluminium-magnesium hydrotalcite by FTIR analysis and detection of differences in structure due to calcination. Three types of samples were analysed. In the first two samples, cobalt was added into the structure and the third sample contained nickel and zinc. Hydrotalcite was prepared by one of the most common methods of hydrotalcite preparation, co-precipitation. After preparation, the samples were calcined at temperatures from 150 °C to 750 °C. Samples were compared in terms of calcination temperature; but in case of samples containing cobalt, two samples to each other. The most significant changes were noticed in the 500–700 cm−1 region, where a spinel structure was formed at higher calcination temperatures.

Influence of BaO on the catalytic properties and durability of Pd-CZLA for automobile exhaust

2021 ◽  
Vol 4 (1) ◽  
Keyword(s):  
High Temperature ◽  
Temperature Stability ◽  
Catalytic Efficiency ◽  
High Catalytic Activity ◽  
Exhaust Pipe ◽  
High Temperature Stability ◽  
Pd Dispersion ◽  
Car Exhaust ◽  
Nano Alumina ◽  
Co Precipitation

Co-precipitation was used to prepare CeO2-ZrO2-La2O3 (CZL) support, and impregnation was employed to load nano-aluminum sol and Pd to prepare a Pd-CZLA catalyst that can be directly used in car exhaust pipe for the secondary purification of exhaust gas. The specific surface area of the catalyst can reach 143.2 m2/g. At 400 0 C, the catalytic efficiency of the catalyst was 76.47%, 70.59%, and 75.41% for C3H8, CO, and NOx, respectively. After modification through doping with 8% BaO in nano-alumina, the catalyst has enhanced high-temperature stability and maintained its high catalytic activity after aging at 1100 0 C. Scanning electron micrograph showed that the high-temperature sintering of the catalyst is slowed down when modified by BaO addition. Combined barium oxide and nano-alumina acts as a stabilizer that prevents the crystalline phase transition of alumina at high temperature and further stabilizes its structure. This material also stabilizes Pd dispersion and improves CZA supportive protection at high temperature.

Synthesis and characterization of pure and nanosized hydroxyapatite bioceramics

2017 ◽  
Vol 6 (2) ◽  
pp. 149-157 ◽  
Author(s):  
Aneela Anwar ◽  
Qudsia Kanwal ◽  
Samina Akbar ◽  
Aisha Munawar ◽  
Arjumand Durrani ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Calcium Nitrate ◽  
Temperature Stability ◽  
Molar Ratio ◽  
Calcium Nitrate Tetrahydrate ◽  
High Temperature Stability ◽  
X Ray ◽  
Transmission Electron ◽  
Nanosized Hydroxyapatite ◽  
Co Precipitation

AbstractSynthetic nanosized hydroxyapatite (HA) particles (<120 nm) were prepared using a co-precipitation technique by adopting two different routes – one from an aqueous solution of calcium nitrate tetrahydrate and diammonium hydrogen phosphate at pH 10 and the other by using calcium hydroxide and phosphoric acid as precursors at pH 8.5 and reaction temperature of 50°C. The lattice parameters of HA nanopowder were analogous to reference [Joint Committee on Powdered Diffraction Standards (JCPDS)] pattern no. 09-432. No decomposition of HA into other phases was observed even after heating at 1000°C in air for 1 h. This observation revealed the high-temperature stability of the HA nanopowder obtained using co-precipitation route. The effects of preliminary Ca/P molar ratio, precipitation, pH and temperature on the evolution of phase and crystallinity of the nanopowder were systematically examined and optimized. The product was evaluated by techniques such as X-ray-diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and Raman spectroscopy analyses. The chemical structural analysis of the as-prepared HA sample was performed using X-ray photoelectron spectroscopy (XPS). After heat treatment at 1000°C for 1 h and ageing for 15 h, the product was obtained as a phase-pure, highly crystalline HA nanorods.

scholarly journals Co-precipitation Synthesized MnOx-CeO2 Mixed Oxides for NO Oxidation and Enhanced Resistance to Low Concentration of SO2 by Metal Addition

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 519 ◽  
Author(s):  
Jiaming Shao ◽  
Fawei Lin ◽  
Yan Li ◽  
Hairong Tang ◽  
Zhihua Wang ◽  
...  
Keyword(s):  
Calcination Temperature ◽  
Conversion Efficiency ◽  
Mixed Oxides ◽  
No Oxidation ◽  
Precipitation Method ◽  
No Conversion ◽  
So2 Poisoning ◽  
Negative Effect ◽  
Co Precipitation ◽  
Metal Addition

NO oxidation was conducted over MnOx-CeO2 catalysts, which were synthesized by the co-precipitation method. The calcination temperature and third metal doping were the main considerations. MnCe catalysts calcined at 350 °C and 450 °C attained the highest NO conversion efficiency, compared to 550 °C. XRD results suggested that the higher the calcination temperature, the higher the crystallization degree, which led to a negative effect on catalytic activity. Subsequently, Sn, Fe, Co, Cr, and Cu were separately doped into MnCe composites, but no improvement was observed for these trimetallic catalysts in NO conversion. Nevertheless, MnCeSn, MnCeFe, and MnCeCo still exhibited a desirable NO conversion efficiency, so they were tested under SO2 addition together with MnCe catalyst. Among them, MnCeFe exhibited the highest NO conversion after whole poisoning testing. XPS results indicated that Fe could protect Mn and Ce metal oxides from being reduced during SO2 poisoning process. Furthermore, in in-situ DRIFTS measurement, part of nitrate species maintained undestroyed on the MnCeFe catalyst surface after SO2 poisoning. These characteristics reinforced that Fe dropping would achieve better performance under SO2 atmosphere.

The Activity and Characterization of Pd/Ce0.5Zr0.5O2 Catalyst for the Reduction of NO

2013 ◽  
Vol 800 ◽  
pp. 93-97
Author(s):  
Xue Tao Wang ◽  
Xu Bin ◽  
Shu Juan Kang ◽  
Cheng Rui Qu
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
Mixed Oxides ◽  
Space Velocity ◽  
X Ray Diffraction ◽  
Intrinsic Structure ◽  
Pd Catalysts ◽  
Reduction Of No ◽  
Xrd Techniques ◽  
Co Precipitation

Pd catalysts and Ce0.5Zr0.5O2 mixed oxides (CZ) was prepared by co-precipitation technique and their physicochemical properties were characterized by specific surface area measurements (BET), scanning electron microscope (SEM), and X-ray diffraction (XRD) techniques. CeO2-ZrO2 solid solutions supported with Pd are investigated as catalysts for reduction of NO. The research presented in this paper is focused on the intrinsic structure of CeO2-ZrO2 solid solution and catalytic behavior of NO over Pd/Ce0.5Zr0.5O2 mixed oxides catalyst. The incorporation of ZrO2 into the CeO2 framework strongly promotes the reduction of Ce4+ in the bulk of the support. The surface area of Ce0.5Zr0.5O2 was 32 m2/g after calcination in air at 1000 °C for 5 h. XRD results revealed the existence of Zr-rich phase in CZ sample. The experimental results show that the best Pd/Ce0.5Zr0.5O2 catalyst yielded 97.75% NO conversion at typical reaction temperatures (280-320 C) and the high gas hourly space velocity of 15,000 h1. The effect of the calcination temperature was also investigated, and the optimal calcination temperature was 400-500 C.

Synthesis of Nd:YAG Powders by the Co-Precipitation Method

2011 ◽  
Vol 239-242 ◽  
pp. 3306-3309
Author(s):  
Xiang Yu Zou ◽  
Hong Bo Zhang ◽  
Chun Hui Su
Keyword(s):  
Yttrium Aluminum Garnet ◽  
Laser System ◽  
Temperature Stability ◽  
Optical Quality ◽  
Raw Material ◽  
Precipitation Method ◽  
High Temperature Stability ◽  
Co Precipitation ◽  
Precursor Powders ◽  
New Generation

Yttrium Aluminum Garnet (Nd:YAG) transparent ceramic doped with Nd have predominantly chemical stability, excellent optical quality and high temperature stability, it is becomeing a substitute for single crystal, had already become new generation laser material, have important strategic sense in the laser and the superelevation powders laser system. Al(NO3)3·9H2O, Y2O3, Nd2O3,(NH4)2SO4 and NH4HCO3 are raw material, TEOS is additive and ethylene glycol(EG). Nd:YAG precursor powders witch is Homogeneously dispersed, little agglomerated, pure YAG phase, different Nd3+ doped density were prepared by the co-precipitation method. The Nd:YAG ceramic powders were characterized by TG-DTA, XRD, FT-IR.

scholarly journals Synthesis of Spinel Nanocrystalline ZnFe2O4: Structural, Optical, Magnetic and Electrical properties.

2021 ◽  
Author(s):  
Sasirekha Chelladurai ◽  
Raghavan Chandrasekaran ◽  
Sivaraman Murugasen
Keyword(s):  
Electrical Properties ◽  
Calcination Temperature ◽  
Optical Band Gap ◽  
Low Cost ◽  
Band Gap Energy ◽  
Precipitation Method ◽  
Calcination Temperatures ◽  
Paramagnetic Behavior ◽  
Co Precipitation ◽  
Magnetic And Electrical Properties

Abstract The present paper deals with the synthesis of Zinc Ferrite (ZnFe2O4) nanoparticles using simple, low cost co - precipitation method and study the structural, optical, magnetic and electrical properties. The samples have been prepared at two different calcination temperatures of 400˚ C and 600˚ C. The XRD studies indicate that the synthesized ZnFe2O4 samples exhibit cubic spinel structure and that the grain size increases with calcination temperature. The FTIR spectra demonstrate bands associated with metal – oxygen bonds in the tetrahedral and octahedral sites. Moreover, no unwanted impurity such as nitrate has been detected in the synthesized samples revealing their high purity. The micro structural analysis shows that though most particles are irregular granular ones, some are spherical. The optical band gap energy is found to increase with increasing calcination temperature. The Vibrating Sample Magnetometer (VSM) studies reveal the super paramagnetic behavior of the synthesized samples, even for a high Fe: Zn ratio of 1:2. The electrical resistivity of the samples decreases with increase in calcination temperature.This phenomenon has been explained on the basis of the Verwey-de Boer mechanism.

scholarly journals PENGARUH TEMPERATUR KALSINASI DAN SUBSITUSI LOGAM NIKEL PADA PEMBENTUKAN FASA BARIUM M-HEXAFERRITTE (BaFe12-xNixO19) MENGGUNAKAN FTIR

2015 ◽  
Vol 10 (1) ◽  
Author(s):  
Susilawati Susilawati ◽  
Munib Munib ◽  
Aris Doyan
Keyword(s):  
Fourier Transform ◽  
Calcination Temperature ◽  
Barium Hexaferrite ◽  
Precipitation Method ◽  
Nickel Metal ◽  
Calcination Temperatures ◽  
Infra Red ◽  
M Phase ◽  
Materials Used ◽  
Co Precipitation

Abstrak: Sintesis Barium M-Hexaferrite (BaFe12-xNixO19) doping logam nikel telah dilakukan dengan metode korpresipitasi dan efeknya terhadap perubahan temperatur dan subsitusi dopan. Bahan dasar yang digunakan dalam sintesis BaCO3, FeCl3.6H2O dan logam nikel. Dalam penelitian ini digunakan variasi temperatur kalsinasi 80, 400, 600 dan 800°C selama 4 jam dengan variasi dopan 0; 0,4; 0,7 dan 0,9. Hasil sintesis dikarakterisasi dengan FTIR (Fourier Transform Infra Red Spectroscopy) merek Shimidzu tipe 8400 s. Hasil pembentuka fasa dari barium M-hexaferrite (BaFe12-xNixO19) diketahui melalui data FTIR seiring dengan meningkatkan temperatur kalsinasi yang digunakan diperoleh puncak yang muncul pada rentang bilangan gelombang 800 - 1650 cm-1 semakin sedikit, sehingga pembentukan fasa barium M-hexaferrite yang signifikan terbentuk pada temperatur kalsinasi 800 °C dan pada variasi dopan 0,7.Kata kunci:   Temperatur, dopan, barium M-hexaferrite, kopresipitasi Abstract: Synthesis of Barium M-Hexaferrite (BaFe12-xNixO19) nickel metal doping have been done with co-precipitation method and its effect on temperature changes and substitution dopants. Basic materials used in the synthesis of BaCO3, FeCl3.6H2O and nickel metal. This study used a variation of calcination temperature of 80, 400, 600 and 800°C for 4 hours with a variety of dopants 0; 0.4; 0.7 and 0.9. Synthesized characterized by FTIR (Fourier Transform Infra Red Spectroscopy) Shimidzu brand type 8400 s. Results of the phase formation of barium M-hexaferrite (BaFe12-xNixO19) known through the data FTIR along with increasing the calcination temperatures used were obtained peak appearing in the range of wavenumber 800 to 1650 cm-1 is getting a little bit, so the formation of M-phase barium hexaferrite significant formed at calcination temperature of 800 ° C and at variations of dopant  0.Key words: temperature, dopant, barium M-hexaferrite, co-precipitation

Microstructure and reactivity of small metal particles: The role of Ce additives

1992 ◽  
Vol 50 (1) ◽  
pp. 318-319
Author(s):  
L.D. Schmidt ◽  
K. R. Krause ◽  
J. M. Schwartz ◽  
X. Chu
Keyword(s):  
Atmospheric Pressure ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Chemical Shifts ◽  
Catalytic Converter ◽  
Structural Evolution ◽  
Single Particles ◽  
Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

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