scholarly journals Textural, Structural and Catalytic Properties of ZnCr2O4–A12O3 Ternary Solid Catalysts

1998 ◽  
Vol 16 (3) ◽  
pp. 193-216 ◽  
Author(s):  
E.A. El-Sharkawy
Keyword(s):  
Textural Properties ◽  
X Ray Diffraction ◽  
Solid Catalysts ◽  
Catalytic Activities ◽  
Ion Contents ◽  
Ft Ir ◽  
Adsorption Desorption ◽  
Ir Spectroscopic

Two series of ternary solid catalysts containing Al, Cr and Zn but with different ZN2+ or Cr3+ ion contents were prepared by impregnation methods. All systems were calcined by heating within the temperature range 773–1073 K. Structural characterization of the systems was effected by X-ray diffraction (XRD) methods and by differential thermal analysis (DTA). The textural properties of the precalcined products were measured from adsorption/desorption studies of nitrogen at 77 K. The surface acidities of the precalcined products were also studied using a poisoning method employing pyridine as the probe base. The adsorption and disproportionation of NO at 298 K was followed via in-situ FT-IR spectroscopic methods, while the catalytic activities of the prepared samples towards the dehydration (DHD)/dehydrogenation (DHG) of propan-2-ol were studied using a pulse microcatalytic technique. XRD and DTA analyses showed the presence of γ-A12O3 and ZnCr2O4 in the prepared samples but did not provide any evidence for other detectable species in the ternary solid materials. The disproportionation of NO, as well as the catalytic conversion of propan-2-ol, was apparently strongly influenced by the structural properties of these materials but to a lesser extent by their textural properties.

scholarly journals In-Exchanged CHA Zeolites for Selective Dehydrogenation of Ethane: Characterization and Effect of Zeolite Framework Type

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 807
Author(s):  
Zen Maeno ◽  
Xiaopeng Wu ◽  
Shunsaku Yasumura ◽  
Takashi Toyao ◽  
Yasuharu Kanda ◽  
...  
Keyword(s):  
Active Sites ◽  
Temperature Programmed Desorption ◽  
X Ray Diffraction ◽  
Zeolite Framework ◽  
X Ray ◽  
Catalytic Activities ◽  
Ethane Dehydrogenation ◽  
Temperature Programmed

In this study, the characterization of In-exchanged CHA zeolite (In-CHA (SiO2/Al2O3 = 22.3)) was conducted by in-situ X-ray diffraction (XRD) and ammonia temperature-programmed desorption (NH3-TPD). We also prepared other In-exchanged zeolites with different zeolite structures (In-MFI (SiO2/Al2O3 = 22.3), In-MOR (SiO2/Al2O3 = 20), and In-BEA (SiO2/Al2O3 = 25)) and different SiO2/Al2O3 ratios (In-CHA(Al-rich) (SiO2/Al2O3 = 13.7)). Their catalytic activities in nonoxidative ethane dehydrogenation were compared. Among the tested catalysts, In-CHA(Al-rich) provided the highest conversion. From kinetic experiments and in-situ Fourier transform infrared (FTIR) spectroscopy, [InH2]+ ions are formed regardless of SiO2/Al2O3 ratio, serving as the active sites.

scholarly journals Fabrication of the Hierarchical HZSM-5 Membrane with Tunable Mesoporosity for Catalytic Cracking of n-Dodecane

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 155 ◽  
Author(s):  
Zhenheng Diao ◽  
Lushi Cheng ◽  
Xu Hou ◽  
Di Rong ◽  
Yanli Lu ◽  
...  
Keyword(s):  
Catalytic Cracking ◽  
Inductively Coupled Plasma ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
Inductively Coupled ◽  
Swelling Agent ◽  
Ft Ir ◽  
Temperature Programmed ◽  
Adsorption Desorption

Hierarchical HZSM-5 membranes were prepared on the inner wall of stainless steel tubes, using amphiphilic organosilane (TPOAC) and mesitylene (TMB) as a meso-porogen and a swelling agent, respectively. The mesoporosity of the HZSM-5 membranes were tailored via formulating the TPOAC/Tetraethylorthosilicate (TPOAC/TEOS) ratio and TMB/TPOAC ratio, in synthesis gel, and the prepared membranes were systematically characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption–desorption, N2 permeation, inductively coupled plasma (ICP), in situ fourier transform infrared (FT-IR), ammonia temperature-programmed desorption (NH3-TPD), etc. It was found that the increase of the TPOAC/TEOS ratio promoted a specific surface area and diffusivity of the HZSM-5 membranes, as well as decreased acidity; the increase of the TMB/TPOAC ratios led to an enlargement of the mesopore size and diffusivity of the membranes, but with constant acid properties. The catalytic performance of the prepared HZSM-5 membranes was tested using the catalytic cracking of supercritical n-dodecane (500 °C, 4 MPa) as a model reaction. The hierarchical membrane with the TPOAC/TEOS ratio of 0.1 and TMB/TPOAC ratio of 2, exhibited superior catalytic performances with the highest activity of up to 13% improvement and the lowest deactivation rate (nearly a half), compared with the microporous HZSM-5 membrane, due to the benefits of suitable acidity, together with enhanced diffusivity of n-dodecane and cracking products.

scholarly journals Synthesis and Characterization of New Polyimide/Organoclay Nanocomposites Containing Benzophenone Moieties in the Main Chain

2017 ◽  
Vol 57 (2) ◽  
Author(s):  
Khalil Faghihi ◽  
Mostafa Ashouri ◽  
Akram Feyzi
Keyword(s):  
Main Chain ◽  
In Situ Polymerization ◽  
Clay Content ◽  
Nanocomposite Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

<p>A series of nanocomposites consist of organic polyimide and organo-modified clay content varying from 0 to 5 wt%, were successfully prepared by in situ polymerization. Polyimide used as a matrix of nanocomposite was prepared through the reaction of 1,4-bis [4-aminophenoxy] butane (APB) and 3،3΄،4،4΄-benzophenone tetra carboxylic dianhydride (BTDA) in N,N-dimethylacetamide (DMAc). The resulting nanocomposite films were characterized by FT-IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA).</p>

Molecular and X-ray Spectroscopies for Noninvasive Characterization of Mayan Green Stones from Bonampak, Chiapas

2019 ◽  
Vol 73 (9) ◽  
pp. 1074-1086
Author(s):  
Valentina Aguilar-Melo ◽  
Alejandro Mitrani ◽  
Edgar Casanova-Gonzalez ◽  
Mayra D. Manrique-Ortega ◽  
Griselda Pérez-Ireta ◽  
...  
Keyword(s):  
Archaeological Site ◽  
Molecular Techniques ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Noninvasive Characterization ◽  
A Minor

A burial and a rich offering were found under Room 2 in the Murals Building, Bonampak, a Mayan archaeological site situated in Chiapas, Mexico. This burial may be related with the creation of the famous mural paintings. A rich set of jewelry made of green stones was among the different objects found. Green stones have great importance in Mesoamerican cultures, those composed of jadeite being the most appreciated. To characterize the green stones, different spectroscopic techniques were used in a complementary way: Raman and infrared spectroscopies (FT-IR) were used for global mineralogical analysis, while X-ray diffraction (XRD) and X-ray fluorescence (XRF) were applied simultaneously in situ on the artifacts that were not successfully identified by these molecular techniques. In addition, XRF was used to contrasts the elemental information from pieces composed of pyroxenes that may be related to the raw sources of jade in Guatemala. The main minerals identified within the beads and earrings were jadeite with omphacite and jadeite with albite; to a minor extent, quartz, and serpentine. In this paper, the main features of the molecular and X-ray techniques are compared in order to determine the advantages and limitations of these spectroscopies for mineral identification. With this combination of techniques, it was possible to undertake a suitable characterization of the analyzed objects. This paper focuses on the XRD–XRF combined analysis for in situ noninvasive characterization.

scholarly journals Efficiency of TiO2 catalyst supported by modified waste fly ash during photodegradation of RR45 dye

2019 ◽  
Vol 26 (1) ◽  
pp. 292-300 ◽  
Author(s):  
Vanja Gilja ◽  
Zvonimir Katančić ◽  
Ljerka Kratofil Krehula ◽  
Vilko Mandić ◽  
Zlata Hrnjak-Murgić
Keyword(s):  
Fly Ash ◽  
Gas Adsorption ◽  
Sol Gel ◽  
Efficiency Evaluation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sol Gel Synthesis ◽  
Adsorption Desorption

AbstractThe waste fly ash (FA) material was subjected to chemical treatment with HCl at elevated temperature for a different time to modify its porosity. Modified FA particles with highest surface area and pore volume were further used as a support for TiO2 catalyst during FA/TiO2 nanocomposite preparation. The nanocomposite photocatalysts were obtained by in situ sol–gel synthesis of titanium dioxide in the presence of FA particles. To perform accurate characterization of modified FA and FA/TiO2 nanocomposite photocatalysts, gas adsorption-desorption analysis, X-ray diffraction, scanning electron microscopy, UV/Vis and Infrared spectroscopy were used. Efficiency evaluation of the synthesized FA/TiO2 nanocomposites was performed by following the removal of Reactive Red 45 (RR45) azo dye during photocatalytic treatment under the UV-A irradiation. Photocatalysis has been carried out up to five cycles with the same catalysts to investigate their stability and the possible reuse. The FA/TiO2 photocatalyst showed very good photocatalytic activity and stability even after the fifth cycles. The obtained results show that successfully modified waste fly ash can be used as very good TiO2 support.

Synthesis and Characterization of ZrO2/Graphene Nanocomposite Materials

2012 ◽  
Vol 531 ◽  
pp. 161-164 ◽  
Author(s):  
Zong Hua Wang ◽  
Fu Qiang Zhu ◽  
Jan Fei Xia ◽  
Fei Fei Zhang ◽  
Yan Zhi Xia ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Transmission Electron ◽  
Ft Ir ◽  
Graphene Nanocomposite ◽  
Adsorption Desorption

Zirconia/graphene (ZrO2/graphene) nanocomposite has been successfully synthesized by a simple method. The as-prepared nanocomposite was characterized using transmission electron microscopy (TEM), FT-IR spectroscopy, power X-ray diffraction (XRD) and nitrogen adsorption-desorption. It was found that tetragonal ZrO2was uniformly deposited on graphene, which resulted in the formation of two-dimensional nanocomposite, it showed a high surface area of 165 m2/g.

Preparation and Characterization of Cobalt Modified Rectorite

2013 ◽  
Vol 773 ◽  
pp. 263-266 ◽  
Author(s):  
Xiao Rong Zhao ◽  
Li Hua Zhu ◽  
He Qing Tang
Keyword(s):  
Nitrogen Adsorption ◽  
Interlayer Spacing ◽  
X Ray Diffraction ◽  
Step Method ◽  
Bet Specific Surface Area ◽  
Pore Properties ◽  
Adsorption Desorption ◽  
Resultant Material

Cobalt modified rectorite (Co@R) was prepared from sodium saturated rectorite (Na-R) with a two-step method of microwave-assisted ion-exchange and in-situ hydrolysis. The morphology, composite structure and pore properties of Co@R were observed with scanning electron microscopy (SEM), small angle X-ray Diffraction (XRD) and nitrogen adsorption-desorption isotherm. The adsorption ability and catalytic behavior of Co@R were studied with methyl blue (MB) as probe contaminant. The interstratified layered Na-R was stripped fully and the resultant material remained the layered structure with a slit-shaped pore between the layers of lamellar particles. The interlayer spacingd001of rectorite was increased successfully from 2.23 nm up to 2.72 nm. The Co@R has a BJH pore volume of 0.091 cm3g-1resulting from the macropores and BET specific surface area of 28.5 m2g-1. A set of test has shown that Co@R possesses the potential to become a good adsorbent and catalyst for activating peroxymonosulfate (PMS), removing organic pollutants efficiently.

Synthesis and characterization of magnetic Ni0.3 Zn0.7 Fe2 O4/polyvinyl acetate (PVAC) nanocomposite

2014 ◽  
Vol 34 (9) ◽  
pp. 823-828
Author(s):  
Fatemeh S. Mohammad Doulabi ◽  
Mohsen Mohsennia ◽  
Shervin Taraghikhah
Keyword(s):  
Magnetic Nanoparticles ◽  
Polyvinyl Acetate ◽  
Nickel Chloride ◽  
X Ray Diffraction ◽  
Phase Spinel ◽  
Ft Ir ◽  
Xrd Patterns ◽  
Synthesized Materials

Abstract The magnetic Ni0.3 Zn0.7 Fe2 O4 nanoparticles were expected to have wide applications in bionanoscience and electronic devices technology. In this work, Ni0.3 Zn0.7 Fe2 O4 nanoparticles were synthesized successfully by a redox chemical reaction in an aqueous solution of nickel chloride, zinc chloride and ferric chloride. Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the shape, structure and size of the synthesized magnetic nanoparticles. The magnetic properties of Ni0.3 Zn0.7 Fe2 O4 nanoparticles were studied using a vibrating sample magnetometer (VSM). The XRD patterns of the synthesized nanoparticles revealed the formation of the single phase spinel structure of the synthesized materials. The synthesized Ni0.3 Zn0.7 Fe2 O4 nanoparticles were used for the preparation of Ni0.3 Zn0.7 Fe2 O4/polyvinyl acetate (PVAC) nanocomposites by an in situ emulsion polymerization method. The synthesized Ni0.3 Zn0.7 Fe2 O4 nanoparticles exhibited superparamagnetic behavior at the room temperature under an applied magnetic field. Magnetization measurements indicated that the saturation magnetization of synthesized Ni0.3 Zn0.7 Fe2 O4/PVAc nanocomposites was markedly less than that of Ni0.3 Zn0.7 Fe2 O4 magnetic nanoparticles.

Study on Preparation and Characterization of Modified Montmorillonite with the Aromatic Isocyanate

2013 ◽  
Vol 662 ◽  
pp. 297-300
Author(s):  
Xiao Hua Gu ◽  
Xi Wei Zhang ◽  
Jia Liang Zhou ◽  
Bao Yun Xu
Keyword(s):  
Smart Materials ◽  
In Situ Polymerization ◽  
Heat Stability ◽  
X Ray Diffraction ◽  
Modified Polymer ◽  
Highly Active ◽  
Detection Analysis ◽  
Ft Ir

In this article, the methylene diphenyl isocyanate (MDI) containing two benzene rings was used to modify montmorillonite. The detection analysis of the original MMT and the samples after modification were investigated by infrared spectroscopy (FT-IR), x-ray diffraction (XRD) and thermo gravimetry (TG). Analysis of detection results shows that MDI and the surface of montmorillonite form chemical bonds and the spacing of montmorillonite layer increases from 1.24 nm to 1.86 nm. It provides highly active terminal isocyanate groups in situ polymerization for the montmorillonite and smart materials. It will improve the compatibility of the MMT and polymer, and allows the montmorillonite have always been able to maintain a good dispersion in polymer. Meanwhile the diphenyl isocyanate into ring can improve the heat stability of montmorillonite-modified polymer.

Xavier Guerrero, De México a Chile (From Mexico to Chile), Some Remarks About the Use of Portland Cement in Mexican Muralism

2012 ◽  
Vol 1374 ◽  
pp. 73-85
Author(s):  
Sandra Zetina Ocaña ◽  
Manuel Espinosa Pesqueira ◽  
Nora Ariadna Pérez Castellanos ◽  
Renato Robert Pappereti
Keyword(s):  
Portland Cement ◽  
Textural Properties ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Stratigraphic Sequence ◽  
Diego Rivera ◽  
Setting Process ◽  
Mexican Government ◽  
Adsorption Desorption

ABSTRACTXavier Guerrero (1896-1974) had an important role in the so-called Mexican Mural Renaissance, as a technical leader in the murals painted by Roberto Montenegro and Diego Rivera in the early 1920’s. Jean Charlot, Diego Rivera and David Alfaro Siqueiros considered him as a sophisticated fresco craftsman, whose knowledge came from a popular mural painters guild.In 1941 the Mexican Government donated a School to Chillan, a Chilean town almost destroyed by a strong earthquake. David Alfaro Siqueiros and Xavier Guerrero were commissioned to paint murals on the Mexico School. Between 1941-1942 Guerrero decorated several walls and the staircase ceiling, the mural program is called De México a Chile (From Mexico to Chile). In 2010 another earthquake destroyed part of the ceiling. This study is part of the diagnosis project of De México a Chile, and consists in the characterization of the mortar and painting layers with optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis (TGA), while textural properties of the mortars were studied with nitrogen adsorption-desorption techniques.Analytical results show a stratigraphic sequence composed of several layers of Portland and lime combinations, and also an interesting painting technique that possibly involves the Portland cement setting process, with the development of specular gypsum.

Sign in / Sign up

Export Citation Format

Share Document