Novel Keggin-type H 4 PVMo 11 O 40 -based ionic liquid catalysts for n -caprylic acid esterification

Han, Xiaoxiang; Chen, Keke; Du, Huan; Tang, Xiujuan; Hung, Chin‐Te; Lin, Kaifeng; Liu, Shang-Bin

doi:10.1016/j.jtice.2015.07.005

Cited by 14 publications

(4 citation statements)

References 45 publications

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“…A new series of catalysts, which combine acidic ionic liquid (IL) with heteropolyacid (HPA) to form an organic–inorganic composites, have been developed and utilized for conversion of biomass. ,− Owing to the “green solvent” nature of ILs − and “pseudoliquid” and superacidic characteristic of HPA, , the IL-HPA hybrid catalysts are highly soluble to water and other polar solvents. As such, these water-tolerable IL-HPA hybrids may be utilized not only for heterogeneous catalysis but also for homogeneous reactions if carried out under proper solvents .…”

Section: Applications Of 31p Nmr For Acidity Characterization Of Vari...mentioning

confidence: 99%

³¹P NMR Chemical Shifts of Phosphorus Probes as Reliable and Practical Acidity Scales for Solid and Liquid Catalysts

2017

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Acid-base catalytic reaction, either in heterogeneous or homogeneous systems, is one of the most important chemical reactions that has provoked a wide variety of industrial catalytic processes for production of chemicals and petrochemicals over the past few decades. In view of the fact that the catalytic performances (e.g., activity, selectivity, and reaction mechanism) of acid-catalyzed reactions over acidic catalysts are mostly dictated by detailed acidic features, viz. type (Brønsted vs Lewis acidity), amount (concentration), strength, and local environments (location) of acid sites, information on and manipulation of their structure-activity correlation are crucial for optimization of catalytic performances as well as innovative design of novel effective catalysts. This review aims to summarize recent developments on acidity characterization of solid and liquid catalysts by means of experimental P nuclear magnetic resonance (NMR) spectroscopy using phosphorus probe molecules such as trialkylphosphine (TMP) and trialkylphosphine oxides (RPO). In particular, correlations between the observed P chemical shifts (δP) of phosphorus (P)-containing probes and acidic strengths have been established in conjuction with density functional theory (DFT) calculations, rendering practical and reliable acidity scales for Brønsted and Lewis acidities at the atomic level. As illustrated for a variety of different solid and liquid acid systems, such as microporous zeolites, mesoporous molecular sieves, and metal oxides, the P NMR probe approaches were shown to provide important acid features of various catalysts, surpassing most conventional methods such as titration, pH measurement, Hammett acidity function, and some other commonly used physicochemical techniques, such as calorimetry, temperature-programmed desorption of ammonia (NH-TPD), Fourier transformed infrared (FT-IR), and H NMR spectroscopies.

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Section: Applications Of 31p Nmr For Acidity Characterization Of Vari...mentioning

confidence: 99%

³¹P NMR Chemical Shifts of Phosphorus Probes as Reliable and Practical Acidity Scales for Solid and Liquid Catalysts

2017

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“…[23] In brief, varied stoichiometric amounts of HPAs, SAFILs, and water were put into athree-necked flask, then, the mixture was kept at 363 Kwhile stirring continuously for 24 h. After removing the water,t he obtained solid product was washed with diethyl ether followed by drying under vacuum. 40 (i.e.,w ith x = 1), and various ion-exchanged and/or heteroatom-substituted HPA [48] were also prepared together with as eries of active solid oxides (CeMTiO;M = Mn, Fe, Cu, Zn, and Ag) synthesized by using as ol-gel method, [15] as listed in Ta ble 1.…”

Section: Methodsmentioning

confidence: 99%

“…As a result, a series of organic STA salts may be obtained, for example, for the DMBPS IL series, the composite catalysts were expressed as [DMBPSH] x H 4− x SiW 12 O 40 , where x= 1–4 represents the DMBPS/STA molar ratio. For comparison purposes, other SAFIL–STA composite salts, for example, [DMPPSH]H 3 SiW 12 O 40 , [TEAPSH]H 3 SiW 12 O 40 , [MIMPSH]H 3 SiW 12 O 40 , and [PPSH]H 3 SiW 12 O 40 (i.e., with x= 1), and various ion‐exchanged and/or heteroatom‐substituted HPA were also prepared together with a series of active solid oxides (CeMTiO; M=Mn, Fe, Cu, Zn, and Ag) synthesized by using a sol‐gel method, as listed in Table .…”

Section: Methodsmentioning

confidence: 99%

Ionic Liquid–Silicotungstic Acid Composites as Efficient and Recyclable Catalysts for the Selective Esterification of Glycerol with Lauric Acid to Monolaurin

et al. 2016

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The synthesis of glycerol monolaurate (GML) by the esterification of glycerol (GL) with lauric acid (LA) over a series of propyl sulfonic acid‐functionalized ionic liquids (SAFILs)‐modified silicotungstic acid (STA; H4SiW12O40) composite catalysts has been investigated. The synthesized organic–inorganic hybrid catalysts were characterized by different physicochemical techniques. In particular, their acidic properties were studied by solid‐state 31P magic angle spinning (MAS) NMR spectroscopy by using adsorbed trimethylphosphine oxide (TMPO) as a probe. The effects of key reaction parameters, such as glycerol/lauric acid molar ratio, amount of catalyst, reaction time, and reaction temperature on LA conversion and GML product yield were elucidated and optimized with response surface methodology (RSM). The N,N‐dimethyl(benzyl)ammonium propyl sulfobetaine (DMBPS)‐modified STA [DMBPSH]H3SiW12O40 exhibited the optimal catalytic activity and was exploited for process optimization. A highest GML yield of 79.1 % was achieved with the optimized reaction conditions. The high catalytic activity of these hybrid catalysts were attributed to strong acidity, low transport resistance, and their “pseudoliquid” characteristics. A kinetic study was made based on a second‐order irreversible model of the esterification reaction, which resulted in an activation energy of 39.49 kJ mol−1 for [DMBPSH]H3SiW12O40 under optimized reaction conditions.

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“…Li et al [21] synthesized photoanodes containing HPA of dye-sensitized solar cells using a solvothermal method, which resulted in an improvement of 49.2 % of the solar electric energy conversion efficiency compared to the performance of photoanodes without HPA. As a novel HPA-based ionic liquid catalyst for ncaprylic acid esterification, Han et al [22] found that there was only 3 % loss in catalytic activity over six consecutive runs, implying excellent durability and recyclability of the catalyst.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and electrocatalytic performance of phosphotungstic acid-modified Ag@Pt/MWCNTs catalysts for oxygen reduction reaction

Wang

Zhu

et al. 2016

J Appl Electrochem

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Keggin-structured phosphotungstic acid H 3 PW 12 O 40 (HPW)-modified Ag@Pt/MWCNTs electrocatalysts were successfully prepared using a chemical impregnation method. Physical characterization by X-ray powder diffraction, high-resolution transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy revealed that the HPW molecules were incorporated into the Ag@Pt/MWCNT structure The diameter of the catalyst used was about 4.0 nm, and electrochemical investigation results indicated that HPW could ameliorate electrocatalytic activity. The catalyst with HPW content of 25 % displayed the best excellent electrocatalytic activity with an electrochemically active area of 83.62 m 2 g -1 and a half-wave potential for the oxygen reduction reaction of 0.851 V, all ascribed to the high utilization of Pt and the protective effect of the HPW layer on the catalyst surface. The synergic effect of the HPW and Ag@Pt enhanced the rate of electron transfer and increased the catalytic efficiency of oxygen reduction reaction, influencing 4e -reduction reactions on Ag@Pt/MWCNTs-HPW catalysts. Graphical AbstractPhosphotungstic acid-modified Ag@Pt/MWCNTs catalysts were successfully synthesized by the chemical impregnation method. The morphology and catalytic performance of the prepared catalysts were investigated, leading to the understanding of catalytic mechanism of the catalyst in acidic medium, especially, the importance of HPW in the hybrid catalysts. The investigation indicated that the hybrid catalyst showed excellent activity toward oxygen reduction. Schematic diagram for mechanism of ORR on Ag@Pt/MWCNTs-HPW nanostructure.

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Novel Keggin-type H 4 PVMo 11 O 40 -based ionic liquid catalysts for n -caprylic acid esterification

Cited by 14 publications

References 45 publications

³¹P NMR Chemical Shifts of Phosphorus Probes as Reliable and Practical Acidity Scales for Solid and Liquid Catalysts

³¹P NMR Chemical Shifts of Phosphorus Probes as Reliable and Practical Acidity Scales for Solid and Liquid Catalysts

Ionic Liquid–Silicotungstic Acid Composites as Efficient and Recyclable Catalysts for the Selective Esterification of Glycerol with Lauric Acid to Monolaurin

Synthesis and electrocatalytic performance of phosphotungstic acid-modified Ag@Pt/MWCNTs catalysts for oxygen reduction reaction

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Novel Keggin-type H 4 PVMo 11 O 40 -based ionic liquid catalysts for n -caprylic acid esterification

Cited by 14 publications

References 45 publications

31P NMR Chemical Shifts of Phosphorus Probes as Reliable and Practical Acidity Scales for Solid and Liquid Catalysts

31P NMR Chemical Shifts of Phosphorus Probes as Reliable and Practical Acidity Scales for Solid and Liquid Catalysts

Ionic Liquid–Silicotungstic Acid Composites as Efficient and Recyclable Catalysts for the Selective Esterification of Glycerol with Lauric Acid to Monolaurin

Synthesis and electrocatalytic performance of phosphotungstic acid-modified Ag@Pt/MWCNTs catalysts for oxygen reduction reaction

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Product

Resources

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³¹P NMR Chemical Shifts of Phosphorus Probes as Reliable and Practical Acidity Scales for Solid and Liquid Catalysts

³¹P NMR Chemical Shifts of Phosphorus Probes as Reliable and Practical Acidity Scales for Solid and Liquid Catalysts