Vapor Phase Dehydration of Glycerol to Acrolein Over Phosphotungstic Acid Catalyst Supported on Niobia

Viswanadham, Balaga; Pavankumar, Vanama; Chary, Komandur V. R.

doi:10.1007/s10562-014-1204-x

Cited by 43 publications

(42 citation statements)

References 40 publications

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“…The used catalyst was regenerated and when studied for five cycles showed an atomic ratio of 1.00:11.91:1.45 when compared to fresh catalyst, indicating minimal leaching. The Keggin anion density was calculated previously and reported by Viswanadham et al [5] and it was observed that PMA shows more Keggin ion density than the Cu-PMA catalyst. The BET surface area of pure PMA, fresh and regenerated Cu-PMA is shown in Table 1.…”

Section: Elemental Composition and Bet Surface Areamentioning

confidence: 78%

“…BET surface areas of the catalyst were determined using a Micromeritics AutoChem 2910 instrument with nitrogen physisorption at -196°C, taking 0.0162 nm 2 as the cross-sectional of dinitrogen. FT-IR spectra were recorded on a GC-FT-IR Nicolet 670 spectrometer by the KBr disc method and pyridine adsorption experiments were also studied [5]. The Raman spectra of the samples were collected with a Horbia-Jobin-Yvon LabRam-HR spectrometer equipped with a confocal microscope, 2400/900 grooves/mm gratings and a notch filter.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

“…As a result, heteropolyacid catalysts can be reused after activation or without activation, leading to a more economically sustainable process under solvent free conditions [3]. Heteropolyacid catalysts are used in several reactions such as oxidation and acid catalyzed transformations [4][5][6][7][8][9][10][11]. Among these reactions, the Knoevenagel condensation reaction is an important C-C bond forming reaction and its products are extensively used as intermediates in the manufacture of perfumes, pharmaceuticals and polymers [12,13].…”

Section: Introductionmentioning

confidence: 99%

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The Role of Copper Exchanged Phosphomolybdic Acid Catalyst for Knoevenagel Condensation

et al. 2016

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Cu exchanged heteropolyacid catalysts were synthesized by ion exchange method and characterized using various physico-chemical techniques such as X-ray diffraction (XRD), FT-IR, Raman, BET surface area, temperature programmed desorption (TPD) of ammonia, 31 P NMR, pyridine adsorbed FT-IR spectroscopy, ICP-AES and STEM analysis. XRD diffractograms shows crystallites of heteropolyacid, while FT-IR and Raman spectra indicate that the Keggin ion is retained in the catalysts. 31 P NMR, ammonia TPD and pyridine adsorbed FT-IR spectra results suggest that acidity decreases once Cu was incorporated in the heteropolyacid catalyst. For the Knoevenagel condensation reaction, the Cu exchanged phosphomolybdic acid (Cu-PMA) exhibits better catalytic performance than the phosphomolybdic acid (PMA) catalyst and this is related closely with the structural and acidic properties of the catalyst. Graphical Abstract NC CN R O H CuPMA CN NC R O H CuPMA CN NC R H H Keywords Cu exchanged PMA Á Bi-functional Á Raman spectroscopy Á TPD Á Py-FTIR Á 31 P NMR Á Acidity

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Section: Elemental Composition and Bet Surface Areamentioning

confidence: 78%

Section: Catalyst Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Role of Copper Exchanged Phosphomolybdic Acid Catalyst for Knoevenagel Condensation

et al. 2016

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“…As the calcination temperature increases, the acidity of the catalyst increased up to 500°C and decreased later. This is due to crystallite CsPW the catalysts and further leads to decrease in the surface acidity [38]. The catalytic results over various calcination temperatures are presented in Table 5.…”

Section: Effect Of Calcination Temperaturementioning

confidence: 99%

Synthesis and characterization of Cs-exchanged heteropolyacid catalysts functionalized with Sn for carbonolysis of glycerol to glycerol carbonate

et al. 2015

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Cs exchanged heteropolyacid catalysts functionalized with various Sn contents were prepared by wet impregnation method. These catalysts were characterized by X-ray diffraction, FT-IR, Raman spectroscopy, temperature programmed desorption of ammonia and BET surface area measurements. The catalytic properties of SnCsPW catalysts were evaluated for the synthesis of glycerol carbonate and they exhibit an unprecedented activity for the higher glycerol conversion and selectivity towards glycerol carbonate under vacuum conditions. Sn-functionalized Cs exchanged heteropolyacid catalysts (CsPW) play a significant role in the enhancement of acidity, catalytic activity and stability. The glycerol conversion and the selectivity of carbonate formation mainly depend on the Sn content and acidity of the catalysts. Different reaction parameters such as Sn molar ratio, glycerol to urea molar ratio, reaction temperature were investigated and also optimum conditions were established. The catalyst containing molar ratio of 3:1 Sn-CsPW has shown highest conversion and glycerol carbonate selectivity.

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“…The heteropolyacids phosphotungstic acid (PWA) in the solid state is a pure Brönsted acid and stronger than the conventional solid acids such as SiO 2 , Al 2 O 3 , H 3 PO 4 , and zeolites [9]. Furthermore, the heteropolyacids catalysts do not introduce undesirable side reactions, such as sulfonation and chlorination as well as the corrosion of equipment, which were considered as nontoxic, eco-friendly, and environmentally benign catalysts.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Characterization of Sulfonated Poly (Ether Sulfone) (SPES)/Phosphotungstic Acid (PWA) Hybrid Membranes for Biodiesel Production

Shi

Yang

et al. 2015

Catal Lett

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A new kind of organic-inorganic hybrid membrane based on sulfonated poly (ether sulfone) (SPES) with different degree of sulfonation (DS) embedded phosphotungstic acid (PWA) was prepared as a heterogeneous acid catalyst for biodiesel production. Three kinds of hybrid membranes with the DS of SPES 9.7, 20.3 and 39.1 % were obtained. The interactions between SPES and PWA in SPES/PWA hybrid membrane were characterized by Fourier transform infrared (FTIR), thermogravimetric analysis and X-ray diffraction (XRD). The band shift of FTIR spectrum showed that the PWA particles interacted primarily with sulfonic acid groups on the polymer backbone. Compared to pure SPES membrane, the thermal stability of SPES/PWA hybrid membrane was enhanced. The XRD results suggested that the PWA particles were incorporated inside membrane pores and adhered on the walls outside the pores which were due to the interaction between PWA and SPES polymer matrix. The catalytic properties of SPES/PWA membranes were tested by the esterification of the acidified oil with methanol. The reaction conditions were optimized by response surface model and the optimum conditions were obtained as: methanol/oil mass ratio of 1:1, hybrid membrane loading of 1.66 meq/g and reaction time 6 h with the free fatty acids conversion of 95.3 %. The hybrid membrane with SPES/PWA mass ratio of 2:1 and the membrane thicknesses of 0.06 mm were optimal for the esterification. The SPES/PWA membrane of DS 20.3 % exhibited the best catalytic stabilities among the three kinds of hybrid membranes with different DS with a stable conversion of above 90 % in all times. Graphical Abstract 1 2 3 4 5 0 20 40 60 80 100 Conversion (%)Recycling times DS=9.7% DS=20.3% DS=39.1%

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Vapor Phase Dehydration of Glycerol to Acrolein Over Phosphotungstic Acid Catalyst Supported on Niobia

Cited by 43 publications

References 40 publications

The Role of Copper Exchanged Phosphomolybdic Acid Catalyst for Knoevenagel Condensation

The Role of Copper Exchanged Phosphomolybdic Acid Catalyst for Knoevenagel Condensation

Synthesis and characterization of Cs-exchanged heteropolyacid catalysts functionalized with Sn for carbonolysis of glycerol to glycerol carbonate

Preparation and Characterization of Sulfonated Poly (Ether Sulfone) (SPES)/Phosphotungstic Acid (PWA) Hybrid Membranes for Biodiesel Production

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