scholarly journals Chemical Tuning of Adsorption Properties of Titanate Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Anastasia V. Grigorieva ◽  
Valentina V. Yuschenko ◽  
Irina I. Ivanova ◽  
Eugene A. Goodilin ◽  
Yuri D. Tretyakov
Keyword(s):  
Nitrogen Adsorption ◽  
Temperature Programmed Desorption ◽  
Sodium Content ◽  
Acid Sites ◽  
Adsorption Properties ◽  
Titania Nanotubes ◽  
Sodium Ions ◽  
Lewis Acid Sites ◽  
Adsorption Characteristics ◽  
Temperature Programmed

A conventional hydrothermal method widely used for the preparation of titania-based nanotubes still generates many unsolved questions. One of them is definitely connected with the influence of a posthydrothermal treatment of titania nanotubes on their micromorphology, structure, and adsorption characteristics. Here, it was analyzed systematically by a group of methods including nitrogen adsorption and temperature-programmed desorption of ammonia and carbon dioxide. It is proved that adsorption characteristics and the surface state of titania nanotubes correlate with a sodium content, since sodium ions act as Lewis acid sites and shield Ti4+acid sites of the nanotubes. To obey a balance between chemical and heat treatments of the nanotubes to design their functional properties has been suggested.

scholarly journals Liquid Phase Benzylation of Toluene over Modified Titania Catalysts

2012 ◽  
Vol 11 (2) ◽  
pp. 31-44
Author(s):  
Sunaja Devi K R ◽  
Sugunan S
Keyword(s):  
Liquid Phase ◽  
Lewis Acid ◽  
Benzyl Chloride ◽  
Sol Gel ◽  
Active Phase ◽  
Temperature Programmed Desorption ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Sulfated Titania ◽  
Temperature Programmed

Titania, sulfated titania and a series of iron loaded sulfated titania catalyst with different iron loadings (39 %) are prepared by sol-gel method and calcined at 500°C. Anatase is found to be the active phase with crystallite size in the nano range. All the prepared catalysts are found to be stable up to 700°C. Acidity is measured using spectrophotometric monitoring of adsorption of perylene, thermogravimetric desorption of 2,6-dimethylpyridine and temperature programmed desorption of ammonia. The activities of the catalysts were tested for liquid phase Friedel-Crafts benzylation of toluene with benzyl chloride. It has been concluded that Lewis acid sites are responsible for the reaction.

The acidity of trivalent cation-exchanged montmorillonite. Temperature-Programmed desorption and infrared studies of pyridine and n-butylamine

Clay Minerals ◽  
1987 ◽  
Vol 22 (2) ◽  
pp. 169-178 ◽  
Author(s):  
C. Breen ◽  
A. T. Deane ◽  
J. J. Flynn
Keyword(s):  
Variable Temperature ◽  
Temperature Programmed Desorption ◽  
Acid Sites ◽  
Trivalent Cation ◽  
Desorption Peak ◽  
Lewis Acid Sites ◽  
Ir Studies ◽  
Infrared Studies ◽  
Interlamellar Space ◽  
Temperature Programmed

AbstractTemperature-programmed desorption (TPD) and IR spectroscopy were used to characterize the number and strength of acid sites in Al3+-, Cr3+- and Fe3+-exchanged montmorillonite. The bases pyridine and n-butylamine occupied three different sites in the interlamellar space: (i) physisorbed base, (ii) base bound to Lewis acid sites, and (iii) protonated base. TPD profiles for pyridine were characterized by maxima at 40°, 150° and 340°C, whilst those for n-butylamine occurred at 30°, 200° and 410°C. The Al3+- and Cr3+-exchanged forms were stable up to pretreatment temperatures of 300°C, but the Fe3+-form required > 3 day exposure to base vapour to re-establish the high-temperature desorption peak. Variable-temperature IR studies showed that the number of Brönsted-bound pyridine molecules increased with increased outgassing temperature.

Effects of SiO2/Al2O3 Ratio on Physicochemical Properties and Catalytic Performance of the Non-Templated ZSM-5 Zeolite

2011 ◽  
Vol 197-198 ◽  
pp. 992-995
Author(s):  
Wei Qiao Liu ◽  
Wei Ning Lei ◽  
Tong Ming Shang ◽  
Zhi Gang Mou ◽  
Heng Qiang Wang ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Temperature Programmed Desorption ◽  
Catalytic Performance ◽  
Acid Sites ◽  
X Ray Diffraction ◽  
Lewis Acid Sites ◽  
X Ray ◽  
Transmission Electron ◽  
Ft Ir ◽  
Temperature Programmed

The ZSM-5 zeolites of various SiO2/Al2O3ratios were synthesized without using any template agent. X-ray diffraction (XRD), transmission electron microscope (TEM), temperature- programmed desorption of ammonia (NH3-TPD) and Fourier transform infrared spectroscopy (FT-IR) techniques were employed to analyze the natures of the as-synthesized zeolite. The results show that the as-synthesized non-templated ZSM-5 zeolite is very pure. Meanwhile, Lewis acid sites and Bronsted acid sites are all presented in the as-synthesized non-templated HZSM-5 zeolite. The number of acid sites decreases almost linearly with the increasing of SiO2/Al2O3ratio of the zeolite. In addition, the reaction of propylene oligomerization was carried out over the as-synthesized non-templated HZSM-5 zeolite to evaluate the catalytic properties. The results show that the catalytic activity of propylene oligomerization decreases with the increasing of SiO2/Al2O3ratio.

The Study of Iron Catalyst for Ammonia Synthesis in Chemical Engineering

2012 ◽  
Vol 577 ◽  
pp. 97-100
Author(s):  
Dong Mei Zhao ◽  
Xue Peng Liu
Keyword(s):  
Chemical Engineering ◽  
Hydrogen Adsorption ◽  
Ammonia Synthesis ◽  
Iron Catalyst ◽  
Nitrogen Adsorption ◽  
Temperature Programmed Desorption ◽  
Iron Catalysts ◽  
Synthesis Activity ◽  
Temperature Programmed ◽  
Adsorption Intensity

The temperature programmed desorption technique is used to study the hydrogen adsorption on the catalytic surface of fused iron catalysts with different oxide precursors in chemical engineering. The different catalysts desorption active energy, desorped temperature and their amouts desorped have been attained. The desorption energies, desorped temperatures and desorption amounts have been related to the iron ratio (Fe2+/Fe3+). It is compared with the curve of ammonia synthesis activity against iron ratio. The inhibition of hydrogen in the ammonia synthesis reaction is verified, the adsorption intensity of hydrogen controls the inhibition to nitrogen adsorption

Effect of Rice Husk Ash Based Silicon Dioxide on the Properties of SUZ-4 Zeolite

2017 ◽  
Vol 729 ◽  
pp. 24-29
Author(s):  
Thitipob Sirisoontornpanit ◽  
Atichat Wongkoblab ◽  
Supunnee Junpirom
Keyword(s):  
Silicon Dioxide ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Sol Gel ◽  
Hydrothermal Process ◽  
Temperature Programmed Desorption ◽  
Acid Sites ◽  
Weak Acid ◽  
Molar Ratio ◽  
Temperature Programmed

SUZ-4 zeolite was synthesized by the sol-gel technique, followed by hydrothermal process. The effect of the molar ratio of rice husk ash based silicon dioxide to silica solution was investigated. The synthesized zeolite was characterized by XRD, SEM, N2 adsorption and temperature programmed desorption. The results show that the SUZ-4 zeolite was formed for all investigated conditions. However, the formation of MER zeolite occurred as an impurity for the content of rice husk ash higher than 75%. A needle shape crystal with mainly microporous structure is the feature of synthesized SUZ-4 zeolite. The result of temperature programmed desorption indicated that the chemical surface property of obtained SUZ-4 zeolite was weak acid sites.

The Characterization of Hydrocarbon Intermediates in H-ZSM-5

1987 ◽  
Vol 111 ◽  
Author(s):  
T. J. Gricus Kofke ◽  
R. J. Gorte ◽  
W. E. Farneth
Keyword(s):  
Infrared Spectroscopy ◽  
Thermogravimetric Analysis ◽  
Acid Site ◽  
Adsorbed Molecule ◽  
Temperature Programmed Desorption ◽  
Acid Sites ◽  
Adsorption State ◽  
Brönsted Acid ◽  
Temperature Programmed

AbstractWe have examined the adsorption of simple alcohols and 2-propanamine on H-ZSM-5 zeolites with Si/Al2 ratios between 38 and 520. Thermogravimetric analysis (TGA) demonstrated that most of the molecules display a clearly defined adsorption state corresponding to a coverage of one molecule per Al site. Temperature programmed desorption (TPD) and transmission infrared spectroscopy results for each of the molecules in this 1:1 adsorption state are consistent with adsorption being due to the transfer of a proton from the zeolite to the adsorbed molecule. These results provide additional evidence that carefully prepared H-ZSM-5 is a Bronsted acid, with one acid site per framework Al atom, in which all of the acid sites are identical in strength.

scholarly journals Surface Characteristics of Porous Coconut Shell Carbon Impregnated with Bimetallic Catalysts

2014 ◽  
Vol 695 ◽  
pp. 16-19
Author(s):  
Yakub Ibrahim ◽  
Anwar Mohd Said Khairul ◽  
Norsuzailina Mohamed Sutan ◽  
Yun Hin Taufiq-Yap ◽  
Mahmud Surahim
Keyword(s):  
Selective Catalytic Reduction ◽  
Bimetallic Catalysts ◽  
Catalytic Reduction ◽  
Nitrogen Adsorption ◽  
Ambient Air ◽  
Temperature Programmed Desorption ◽  
Coconut Shell ◽  
Synthesis Process ◽  
Selective Catalytic Reduction Catalyst ◽  
Temperature Programmed

Selective Catalytic Reduction catalyst (Cu-Mn/CSC) was derived from coconut shell carbon (CSC). The bimetallic catalysts, Copper and Manganese (Cu-Mn), were deposited onto CSC using wet impregnation technique while the calcination stage was performed under low temperature ambient air. The samples were then characterized using nitrogen adsorption-and-desorption, carbon dioxide temperature-programmed desorption, ammonia temperature-programmed desorption, hydrogen temperature-programmed reduction as well as scanning electron microscopy. The results showed that the synthesis process increased the external surface area and regulated the distribution of slit-shape pores on Cu-Mn/CSC. Besides, Cu-Mn was found to be reduced and the surface has more acidic groups compared to basic. These findings indicated the potential of using CSC as a precursor for NOx-Selective Catalytic Reduction catalyst.

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