Study of the dehydroxylation of kaolinite and alunite from a Mexican clay with DRIFTS-MS

Clay Minerals ◽  
2016 ◽  
Vol 51 (1) ◽  
pp. 55-68 ◽  
Author(s):  
N.R. Osornio-Rubio ◽  
J.A. Torres-Ochoa ◽  
M.L. Palma-Tirado ◽  
H. Jiménez-Islas ◽  
R. Rosas-Cedillo ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Hydroxyl Groups ◽  
Mineralogical Characterization ◽  
Fourier Transform Spectrometry ◽  
Stretching Vibration ◽  
Kaolinitic Clay ◽  
Diffuse Reflectance Infrared ◽  
Refractory Bricks

AbstractFew reports exist on the use of Diffuse Reflectance Infrared Fourier Transform Spectrometry coupled with Mass Spectrometry (DRIFTS-MS) in situ to monitor the dehydroxylation of kaolinitic clays. The use of DRIFTS-MS in situ allows study of the effect of heat treatment on the dehydroxylation, identifying intensities and temperatures at which the hydroxyl groups are released, forming metakaolinite and meta-alunite. The effluent gases from the infrared cell were analysed by mass spectrometry. The decrease in intensity of the bands at 3694, 3669, 3650 and 3621 cm−1 associated with the −OH stretching vibration modes of AlVI−OH−AlVI of kaolinite began at 450°C. Two additional bands at 3513 and 3485 cm−1 are associated with the vibration of AlVI−OH of alunite that also began to disappear during thermal treatment. Monitoring of the fractions m/e 17 and 18 using a mass spectrometer revealed that the intensity of these fractions increased starting at 450°C. Therefore, it is possible to study the dehydroxylation process of clays during thermal treatment.Chemical and mineralogical characterization of a kaolinitic clay (KN) fromMexico showed that the clay consists of 64.8% kaolinite, 11.0% alunite and 24.4% quartz based on PXRD, EDS, TG/DTA, TEM and FTIR results, and suggested that the material might have potential for use in the manufacture of ceramics, refractory bricks or geopolymers.

Catalytic behavior of unsupported Co materials in the reformation of ethanol to hydrogen: An in situ diffuse reflectance infrared Fourier transform (DRIFT)-mass spectrometry study

2008 ◽  
Vol 80 (11) ◽  
pp. 2397-2403 ◽  
Author(s):  
Salvador Martí ◽  
Narcís Homs ◽  
Evandro Brum Pereira ◽  
Pilar Ramírez de la Piscina
Keyword(s):  
Mass Spectrometry ◽  
Steam Reforming ◽  
Diffuse Reflectance ◽  
Ethanol Steam Reforming ◽  
Hydroxyl Groups ◽  
Subsequent Formation ◽  
Co Catalysts ◽  
Diffuse Reflectance Infrared ◽  
Ethanol Steam

New unsupported Co catalysts were studied in the ethanol steam-reforming reaction by in situ diffuse reflectance infrared spectroscopy and on-line mass spectrometry (MS) techniques. The initial ethoxy surface species evolved to surface-acyl species and to acetaldehyde intermediate at temperatures ca. 473 K. The subsequent formation of surface-acetate species occurs at ca. 573 K. Further, the acetate species mainly evolve above 573 K to H2 and CO2 products. The route to ketone formation was inhibited on these materials. The presence of surface-hydroxyl groups, which are probably related to the formation of a CoO phase under the reforming conditions, was determined. Alkaline addition shows a beneficial effect on the ethanol steam-reforming over bulk Co catalysts.

Dynamic Effects in CO Adsorption on Ru/ZSM-5. Part I: Oxidative Disruption of Ru

1992 ◽  
Vol 46 (8) ◽  
pp. 1279-1287 ◽  
Author(s):  
J. Y. Shen ◽  
A. Sayari ◽  
S. Kaliaguine
Keyword(s):  
Diffuse Reflectance ◽  
Direct Evidence ◽  
Co Adsorption ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Diffuse Reflectance Infrared Spectroscopy ◽  
Adsorption Of Co ◽  
Diffuse Reflectance Infrared

In situ diffuse reflectance infrared spectroscopy of CO adsorption on reduced Ru/ZSM-5 reveals that, under appropriate conditions, in addition to the linearly adsorbed CO on metallic Ru particles (at 2045 ± 10 cm−1), two multicarbonyls involving oxidized Ru can be generated. These multicarbonyl species are characterized by IR doublets at 2080 and 2138 cm−1 and at 2086 and 2150 cm−1, respectively. Direct evidence for the consumption of both types of the ZSM-5 surface hydroxyl groups (silanol and Brønsted) during the oxidative adsorption of CO has been obtained. Each of these two OH types is believed to be associated with one of the multicarbonyl species.

Diffuse Reflectance Infrared Spectroscopic Characterization of Silica Dehydroxylation

1990 ◽  
Vol 44 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Robert L. White ◽  
Aurobindo Nair
Keyword(s):  
Force Constant ◽  
Diffuse Reflectance ◽  
Spectroscopic Characterization ◽  
Absorption Bands ◽  
Stretching Vibration ◽  
Diffuse Reflectance Infrared ◽  
Highly Strained ◽  
Infrared Absorption Bands ◽  
Absorbance Band

Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) is employed to study the dehydroxylation of amorphous silica. Dehydroxylation results in the appearance of infrared absorption bands at 1022, 1107, and 1240 cm−1 assigned to asymmetric stretching vibrations for three different siloxane bridge types. The 1107-cm−1 absorbance band represents a siloxane bridge that is indistinguishable from bulk species. The 1022-cm−1 absorbance band represents a siloxane bridge with a bond angle that is smaller than the bulk, with little change in the stretching vibration force constant. The 1240-cm−1 absorbance band derives from a siloxane bridge characterized by a stretching force constant significantly larger than that of bulk siloxane bridges. This band may be indicative of a highly strained or broken siloxane bridge.

scholarly journals Synthesis and Characterization of TNTs/Polyaniline Composite as Photocatalyst Degradation of Rhodamin B by Visible Light

2017 ◽  
Vol 3 (5) ◽  
pp. 41
Author(s):  
Atik Setyani ◽  
Sri Wahyuni ◽  
Sigit Priatmoko ◽  
Emas Agus Prastyo Wibowo ◽  
Nur Amin
Keyword(s):  
Energy Gap ◽  
In Situ Polymerization ◽  
Anatase Phase ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
Pani Composite ◽  
Stretching Vibration

<p>The purpose of this research is to study the effect of the amount of aniline on their photocatalytic activity. Nano TiO<sub>2</sub> was synthesized using sol-gel method with TiPP precursor. XRD characterization results showed that nano TiO<sub>2</sub> with calcination temperature of 450 °C had size of 13.8 nm with high crystalline. The diffraction peaks of nano TiO<sub>2</sub> at 2θ are 24.45°; 37.075°; 47.26° and 53.18°. Nano TiO<sub>2</sub> was then synthesized with hydrothermal treatment 24 h of 140 °C to produce TNTs. The results of XRD analysis shows anatase phase with field (004) and (200). The morphology of TNTs begins to form at the calcinations temperature of 600 °C with textural coefficient value of 0.998 3 . Synthesis of composite TNTs/PANI (polyaniline) was done by in situ polymerization technique of aniline which was already contained nano TiO<sub>2</sub>. The molar ratio of aniline and APS in the synthesis of a composite is 1:1.5 with the addition of aniline of 15 %; 20 % and 25 % (w/w %). Characterization using FTIR showed the stretching vibration of the C=N in wavelength of 1 600 cm<sup>–1</sup> to mark the formation of quinonoid compounds of polyaniline. The test of the rhodamine B degradation gave the best results on the 25 % TNTs/PANI composite, with the degradation percentage of 58.73 %. The characterization results using dr-uv proved that the decrease of energy gap in the TNTs/PANI composite which as evidenced with Kubelka-Munk calculation equation that was 25 % TNTs/PANI amounting to 3.19 eV and TNTs at 3.24 eV.</p>

scholarly journals Synthesis and Characterization of New Silver (I) N-Heterocyclic Ccarbene Ccomplex Dderived from Imidazol-2-ylidene salt

2018 ◽  
Vol 28 (2) ◽  
pp. 55
Author(s):  
Mohammedl Mujbe Hasson
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Room Temperature ◽  
13C Nmr Spectroscopy ◽  
Synthesis And Characterization ◽  
Imidazolium Salt ◽  
In Situ Method

A new N, N'-imidazolium salt 1-(2,6-diisopropylphenyl)-3- (4,6-dimorpholino -1,3,5-traizine-2-yl)-1H-imidazol-3-ium chloride) as a precursor of N - heterocyclic carbene ligand was prepared via the reaction of 1 - (2, 6 - diisopropyl phenyl - 1H - imidazole) with 1, 3, 5 - triazine derivative bearing morpholine substituent (2, 6 -dimorpholine - 6- chloro-1, 3, 5-triaziazine). Linear coordi-nated Ag (І) NHC complex was synthesised via deprotonation of the imidazolium salt and reac-tion with Ag2O in darkness at room temperature by in situ method. The complex was synthesised for using as transfer agent to prepare another transition metals complexes by transmetallation method in the future. The imidazolium salt and their silver complex have been characterized by 1 H and 13C NMR spectroscopy as well as mass spectrometry.

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