scholarly journals Mesoporous (Ta, Nb)3W7 Modified with Stearic Acid Used as Solid Acids for Esterification

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Fei Chang ◽  
Rui Wang ◽  
Quan Zhou ◽  
Hu Pan ◽  
Heng Zhang
Keyword(s):  
Stearic Acid ◽  
Surface Area ◽  
Heterogeneous Catalysts ◽  
Lower Cost ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Acid Sites ◽  
Solid Acids ◽  
Biodiesel Production ◽  
Preparation Period

Mesoporous solid acids Ta3W7 and Nb3W7 were prepared from TaCl5 and NbCl5 with WCl6 in the presence of stearic acid (SA) via a sol-gel method, respectively. For comparison, mesoporous Ta3W7-P123 mixed oxides and mesoporous Nb3W7-P123 mixed oxides were synthesized in the same way. The catalysts were characterized through TGA, XRD, SEM, TEM, BET, and NH3-TPD. Experimental results showed that Ta3W7-SA and Nb3W7-SA exhibited several advantages such as higher activity, shorter preparation period, lower cost, stronger acid sites, and higher surface area, which had potential to be used as mesoporous heterogeneous catalysts in biodiesel production.

scholarly journals Synthesis and Physico-Chemical Characterization of CeO2/ZrO2-SO42- Mixed Oxides

2017 ◽  
Vol 56 (2) ◽  
Author(s):  
Juan Manuel Hernández-Enríquez ◽  
Rebeca Silva-Rodrigo ◽  
Ricardo García-Alamilla ◽  
Luz Arcelia García-Serrano ◽  
Brent Edward Handy ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Synthesis Method ◽  
Chemical Characterization ◽  
Acid Sites ◽  
Oxide Content ◽  
Physico Chemical

Environmentally friendly solid-acid catalysts CeO<sub>2</sub>/ZrO<sub>2</sub>-SO<sub>4</sub><sup>2-</sup> were prepared by the sol gel method varying CeO<sub>2</sub> content (10, 20 and 30 wt%) and using sulfation <em>in situ</em>, maintaining the sulfate ions amount present in the materials at 20 wt%. ZrO<sub>2</sub> and ZrO<sub>2-</sub>SO<sub>4</sub><sup>2-</sup> were also prepared for comparison proposes using the same synthesis method. The materials were characterized by X-ray diffraction, nitrogen physisorption, potentiometric titration with <em>n</em>-butylamine, decomposition of 2-propanol and <em>n</em>-pentane isomerization. The specific surface area of ZrO<sub>2-</sub>SO<sub>4</sub><sup>2-</sup> was high (160 m<sup>2</sup>/g) compared with the unmodified ZrO<sub>2</sub> (80 m<sup>2</sup>/g), however this area decreased with increasing the CeO<sub>2</sub> content (37-100 m<sup>2</sup>/g). There was no significant effect of CeO<sub>2</sub> on the tetragonal structure of ZrO<sub>2-</sub>SO<sub>4</sub><sup>2-</sup>. The variation of acid sites amount runs parallel to the change of specific surface area. The acid sites amount decreased with increasing cerium oxide content. The decomposition of 2-propanol results fundamentally in the formation of dehydration products such as propylene and diisopropyl ether, both involving acid sites. In addition, a good performance during the <em>n</em>-pentane isomerization was observed for these materials. The selectivity towards isopentane reaches 84% when the Pt/CeO<sub>2</sub>/ZrO<sub>2-</sub>SO<sub>4</sub><sup>2-</sup> catalyst with the highest CeO<sub>2</sub> content was used.

scholarly journals Sol–Gel Entrapped Lewis Acids as Catalysts for Biodiesel Production

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5936
Author(s):  
Mirit Kolet ◽  
Melad Atrash ◽  
Karen Molina ◽  
Daniel Zerbib ◽  
Yael Albo ◽  
...  
Keyword(s):  
Lewis Acids ◽  
Heterogeneous Catalysts ◽  
Fossil Fuels ◽  
Continuous Process ◽  
Sol Gel ◽  
Biodiesel Production ◽  
Esterification Reaction ◽  
Ultrasonic Activation ◽  
Immobilized Catalysts ◽  
Product Separation

Replacing fossil fuels with biodiesel enables the emission of greenhouse gases to be decreased and reduces dependence on fossil fuels in countries with poor natural resources. Biodiesel can be produced by an esterification reaction between free fatty acids (FFAs) and methanol or by transesterification of triglycerides from oils. Both reactions require homogeneous or heterogeneous catalysis. Production of biodiesel catalyzed by heterogeneous catalysts seems to be the preferred route, enabling easy product separation. As we have previously shown, the Lewis acids AlCl3 and BF3 can serve as highly efficient catalysts under ultrasonic activation. The present study focused on the development of oleic acid (OA) esterification with methanol by the same catalysts immobilized in silica matrices using the sol–gel synthesis route. During the course of immobilization, AlCl3 converts to AlCl3 × 6H2O (aluminite) and BF3 is hydrolyzed with the production of B2O3. The immobilized catalysts can be reused or involved in a continuous process. The possibility of biodiesel production using immobilized catalysts under ultrasonic activation is shown for the conversion of FFAs into biodiesel in batch and continuous mode.

scholarly journals Synthesis of Zirconia Doped Molybdenum Oxide as Efficient Catalysts for Ultrasound Assisted Synthesis of Substituted Pyrazoles

2021 ◽  
Vol 33 (9) ◽  
pp. 2007-2014
Author(s):  
Amal A. Muftah ◽  
Shobha A. Waghmode ◽  
Sharda R. Gadale
Keyword(s):  
Photoelectron Spectroscopy ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Temperature Stability ◽  
Acid Sites ◽  
High Yield ◽  
Ultra Sound ◽  
Electron Microscopes ◽  
Temperature Programmed ◽  
Substituted Pyrazoles

To explore green methodology for the synthesis of mixed oxide, its catalytic activity and temperature stability of series of ZrO2/MoO3 and ZrO2 were prepared by sol-gel method and characterized by XRD, FT-IR, X-ray photoelectron spectroscopy (XPS), temperature programmed Desorption (TPD), Raman spectroscopy and transmission electron microscopes (TEM). These mixed oxides were showed high stability with nanocrystalline nature. Due to highly acidic nature of the catalysts, ultra sound assisted synthesis of substituted pyrazoles was carried out successfully with high yield. The reaction was carried out in solvent free medium, which showed green approach and energy saving reaction. Condensation of dibenzoyl methane and hydrazine to form substituted pyrazoles with 97.7% yield. The acid strength and acid amount of synthesized catalysts were determined by temperature programmed desoprtion (TPD), incorporation of zirconia into the molybdenum, network has changed its surface acid properties due to the Zr2+ and Mo6+ ions. After addition of ZrO2 on MoO3, it showed weak and strong acid sites.

Synthesis, Characterization and Catalytic Properties of Al2O3-TiO2 Mixed Oxides Prepared by Sol-Gel

1996 ◽  
Vol 431 ◽  
Author(s):  
A. Montoya ◽  
J. Melé;ndez-Hernindez ◽  
J. M. Domínguez ◽  
G. Sandoval-Robles
Keyword(s):  
Distribution Function ◽  
Radial Distribution Function ◽  
Surface Area ◽  
Long Range ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Sol Gel ◽  
Long Range Order ◽  
Synthesis Parameters ◽  
Mixed Aggregates

AbstractSome synthesis parameters like R-OH/OBu, H20/OBu and composition (Al/Ti) ratios influence the textural and catalytic properties of the mixed Al2O3 -TiO2 oxides. The Radial Distribution Function of the pure and mixed oxides shows that Ti4+ incorporation favors the long-range-order in the mixed aggregates as well as the surface area loss at high temperatures, i.e. 900 °C. The catalytic dehydration of isopropanol towards propylene and the HDS of light gasoils indicate that catalytic properties of the sol-gel mixtures are comparable to the activity of reference catalysts, i.e. Al2O3and Ni/Al2O3.

scholarly journals Glycerol Hydrogenolysis to 1,2-Propanediol over Novel Cu/ZrO2 Catalysts

Catalysts ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 72
Author(s):  
Giuseppina Luciani ◽  
Giovanna Ruoppolo ◽  
Gianluca Landi ◽  
Valentina Gargiulo ◽  
Michela Alfè ◽  
...  
Keyword(s):  
Batch Reactor ◽  
Metal Organic Framework ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Weak Acid ◽  
Copper Deposition ◽  
Biodiesel Production ◽  
Preparation Methods ◽  
Glycerol Hydrogenolysis

Glycerol is the main by-product of biodiesel production; its upgrading to more valuable products is a demanding issue. Hydrogenolysis to 1,2-propanediol is one of the most interesting processes among the possible upgrading routes. In this study, we propose novel copper/zirconia catalysts prepared by advanced preparation methods, including copper deposition via metal–organic framework (MOF) and support preparation via the sol–gel route. The catalysts were characterized by N2 physisorption, X-ray diffraction, Scanning Electron Microscopy, H2-TPR and NH3-TPD analyses and tested in a commercial batch reactor. The catalyst prepared by copper deposition via MOF decomposition onto commercial zirconia showed the best catalytic performance, reaching 75% yield. The improved catalytic performance was assigned to a proper combination of redox and acid properties. In particular, a non-negligible fraction of cuprous oxide and of weak acid sites seems fundamental to preferentially activate the selective pathway. In particular, these features avoid the overhydrogenolysis of 1,2-propanediol to 1-propanol and enhance glycerol dehydration to hydroxyacetone and the successive hydrogenation of hydroxyacetone to 1,2-propanediol.

Effect of Calcination Temperature on Catalyst Surface Area of Ca Supported TiO2 by Sol-Gel Method for Biodiesel Production

2016 ◽  
Vol 818 ◽  
pp. 219-222 ◽  
Author(s):  
Noor Yahida Yahya ◽  
Norzita Ngadi
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
Sol Gel ◽  
Waste Cooking Oil ◽  
Biodiesel Production ◽  
Gel Method ◽  
Bet Model ◽  
Percentage Yield

Currently, the major concern in production of biodiesel is to find a new catalyst which can produce high quality of biodiesel at lower costs. In this study, titania supported CaO catalyst was prepared by a so-gel method. The characterization of catalyst was done using Brunauer-Emmett-Teller (BET) model method to characterize the surface area of the catalyst. Further, the ability of the catalyst for transterification reaction of waste cooking oil (WCO) with methanol was also assessed. The effect of calcination temperature on the catalyst to the transesterification reaction was examined to investigate the relation between catalyst calcination temperature and percentage yield (% yield) of biodiesel production.

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