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.

Sol-Gel Synthesized Fe-P-O Catalyst for the Benzylation of Benzene with Benzyl Chloride

2011 ◽  
Vol 284-286 ◽  
pp. 2141-2145
Author(s):  
Tao Lin ◽  
Xin Zhang ◽  
Rong Li ◽  
Gui Quan Zhang ◽  
Ting Bai
Keyword(s):  
Surface Area ◽  
Lewis Acid ◽  
Benzyl Chloride ◽  
Sol Gel ◽  
Acid Sites ◽  
High Reactivity ◽  
Lewis Acid Sites ◽  
Isothermal Adsorption ◽  
Adsorption Desorption ◽  
Benzylation Of Benzene

Three Fe-P-O catalysts were prepared by different methods. The as-prepared catalysts were comparatively characterized by N2 isothermal adsorption-desorption, XRD, SEM and Py-IR techniques. The reactivity of these catalysts was tested in the benzylation of benzene with benzyl chloride. So-gel prepared Fe-P-O catalyst showed the highest activity among these catalysts and could keep high reactivity even after six reactions cycled because it is not only the large-surface-area superfine particle but also has a large amount of weak and medium Lewis acid sites.

scholarly journals Preparation of Mesoporous Mn–Ce–Ti–O Aerogels by a One-Pot Sol–Gel Method for Selective Catalytic Reduction of NO with NH3

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 475
Author(s):  
Yabin Wei ◽  
Shuangling Jin ◽  
Rui Zhang ◽  
Weifeng Li ◽  
Jiangcan Wang ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Lewis Acid ◽  
Catalytic Reduction ◽  
Sol Gel ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
One Pot ◽  
Gel Method ◽  
Nh3 Scr ◽  
Composite Aerogels

Novel Mn–Ce–Ti–O composite aerogels with large mesopore size were prepared via a one-pot sol–gel method by using propylene oxide as a network gel inducer and ethyl acetoacetate as a complexing agent. The effect of calcination temperature (400, 500, 600, and 700 °C) on the NH3–selective catalytic reduction (SCR) performance of the obtained Mn–Ce–Ti–O composite aerogels was investigated. The results show that the Mn–Ce–Ti–O catalyst calcined at 600 °C exhibits the highest NH3–SCR activity and lowest apparent activation energy due to its most abundant Lewis acid sites and best reducibility. The NO conversion of the MCTO-600 catalyst maintains 100% at 200 °C in the presence of 100 ppm SO2, showing the superior resistance to SO2 poisoning as compared with the MnOx–CeO2–TiO2 catalysts reported the literature. This should be mainly attributed to its large mesopore sizes with an average pore size of 32 nm and abundant Lewis acid sites. The former fact facilitates the decomposition of NH4HSO4, and the latter fact reduces vapor pressure of NH3. The NH3–SCR process on the MCTO-600 catalyst follows both the Eley–Rideal (E–R) mechanism and the Langmuir–Hinshelwood (L–H) mechanism.

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.

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.

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 Effect of Zn/ZSM-5 and FePO4Catalysts on Cellulose Pyrolysis

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Haian Xia ◽  
Xiaopei Yan ◽  
Siquan Xu ◽  
Li Yang ◽  
Yuejie Ge ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Value Added ◽  
Product Distribution ◽  
Acid Sites ◽  
Gas Chromatography Mass Spectrometry ◽  
Lewis Acid Sites ◽  
Liquid Products ◽  
Temperature Programmed ◽  
Xrd Techniques ◽  
Brønsted And Lewis Acid

A series of Zn/ZSM-5 catalysts with different Zn contents and FePO4were used to pyrolyze cellulose to produce value added chemicals. The nature of these catalysts was characterized by ammonia-temperature programmed desorption (NH3-TPD), IR spectroscopy of pyridine adsorption, and X-ray diffraction (XRD) techniques. Noncatalytic and catalytic pyrolytic behaviors of cellulose were studied by thermogravimetric (TG) technique. The pyrolytic liquid products, that is, the biooils, were analyzed by gas chromatography-mass spectrometry (GC-MS). The major components of the biooils are anhydrosugars such as levoglucosan (LGA), 1,6-anhydro-β-D-glucofuranose (AGF), levoglucosenone (LGO, 1,6-anhydro-3,4-dideoxy-β-D-pyranosen-2-one), and 1,4:3,6-dianhydro-α-D-glucopyranose (DGP), as well as furan derivatives, alcohols, and so forth. Zn/ZSM-5 samples with Brønsted and Lewis acid sites and the FePO4catalyst with Lewis acid sites were found to have a significant effect on the pyrolytic behaviors of cellulose and product distribution. These results show that Brønsted and Lewis acid sites modified remarkably components of the biooil, which could promote the production of furan compounds and LGO. On the basis of the findings, a model was proposed to describe the pyrolysis pathways of cellulose catalyzed by the solid acid catalysts.

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.

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