Potassium and Silver Salts of Tungstophosphoric Acid as Catalysts in Dehydration of Ethanol and Hydration of Ethylene

Haber, J.; Pamin, Katarzyna; Matachowski, L.; Napruszewska, Bogna D.; Połtowicz, Jan

doi:10.1006/jcat.2002.3514

Cited by 113 publications

(72 citation statements)

References 24 publications

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“…This is in accordance with literature data, which showed that the lattice parameter of the investigated salt lowered with decrease of the silver content. [13] The Rietveld refinement demonstrated that the concentration of metallic silver phase in the reduced Ag 3 PW 12 O 40 sample was about 12% which corresponds well with the loss of silver ions in the salt structure. These results are in contrast to those obtained by Baba et al [14] who postulated a reversibility of the reduction process of the neutral silver salt.…”

Section: Resultsmentioning

confidence: 88%

Silver nanowires as a result of irradiation or hydrogen reduction of Ag₃PW₁₂O₄₀ salt

Matachowski

Socha

Mucha

et al. 2010

Surface & Interface Analysis

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We report XPS, SEM and XRD investigations of the silver nanowires that are grown at the surface of the neutral silver salt of 12-tungstophosphoric acid (Ag 3 PW 12 O 40 ). Irradiation of the salt with electron or UV beams result in the formation of silver wires in the salt lattice and on the salt surface. The mechanical stress that appears during metallic silver phase formation leads to destruction of the crystal body. The same phenomena were observed after the reduction of Ag 3 PW 12 O 40 in hydrogen. XRD analysis of the processed salts showed two additional reflexes of 2 at 38.12• and 44.28• that originate from the metallic silver phase. SEM analysis showed that the surfaces of the processed salts are covered by bunches of the wires. They show high aspect ratio and rather uniform distribution over the sample. XPS measurements were performed with the fresh and processed silver salts. Hydrogen reduction or irradiation of Ag 3 PW 12 O 40 leads to significant changes in the main component of Ag 3d line. The quantity of the lattice Ag + decreases after reduction, from 93 to 30%. Simultaneously, a new component (metallic silver) appears in the spectrum at a binding energy of 368.0 eV. The amount of metallic silver on the surface of the reduced salt approaches 68% of the total silver concentration in the sample. The analysis of P 2p, O 1s and W 4f core excitations showed no qualitative differences after reduction, which means that the Keggin structure of the treated salt remains unchanged. The latter agrees well with XRD results.

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Section: Resultsmentioning

confidence: 88%

Silver nanowires as a result of irradiation or hydrogen reduction of Ag₃PW₁₂O₄₀ salt

Matachowski

Socha

Mucha

et al. 2010

Surface & Interface Analysis

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“…An increase in the glycerol concentration increases the amount of KOH and decreases the excess of water in the feed. KOH exerts a positive catalytic effect in dehydration reactions [45,46]. In addition, the lower the excess of water, the greater is the shift of the dehydration reactions of glycerol.…”

Section: Liquid Compositionmentioning

confidence: 99%

Analysis and optimisation of H2 production from crude glycerol by steam reforming using a novel two step process

Remón

Jarauta-Córdoba

García

et al. 2016

Fuel Processing Technology

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This work studies the valorisation of biodiesel-derived glycerol to produce a hydrogen rich gas by means of a two-step sequential process. Firstly, the crude glycerol was purified with acetic acid to reduce problematical impurities. The effect of the final pH (5-7) on the neutralisation process was addressed and it was found that a pH of 6 provided the best phase separation and the greatest glycerol purity. Secondly, the refined glycerol was upgraded by catalytic steam reforming and this step was theoretically and experimentally studied. The theoretical study analyses the effect of the temperature (400-700 ºC), glycerol concentration (10-50 wt.%) and N 2 (225-1347 cm 3 STP/min) and liquid flow (0.5-1 mL/min) rates on the thermodynamic composition of the gas. The results show that the temperature and glycerol concentration exerted the greatest influence on the thermodynamics. The experimental study considers the effect of the temperature (400-700 ºC), glycerol concentration (10-50 wt.%) and spatial time (3-17 g catalyst min/ g glycerol) on the product distribution in carbon basis (gas, liquid and solid) and on the composition of the gas and liquid phases. The experiments were planned according to a 2 level 3 factor Box-Wilson Central Composite Face Centred (CCF, :  1) design, which is suitable for studying the influence of each variable as well as all the possible interactions between variables. The results were analysed with an analysis of variance (ANOVA) with 95% confidence, enabling the optimisation of 2 the process. The gas phase was made up of a mixture of H 2 (65-95 vol.%), CO 2 (2-29 vol.%), CO (0-18 vol.%) and CH 4 (0-5 vol.%). Temperatures of 550 ºC and above enabled thermodynamic compositions for the gas to be achieved and helped diminish carbon formation. A possible optimum for H 2 production was found at a temperature of around 680 ºC, feeding a glycerol solution of 37 wt.% and using a spatial time of 3 g catalyst min/g glycerol. These conditions provide a 95% carbon conversion to gas, having the following composition: 67 vol.% H 2 , 22 vol.% CO 2 , 11 vol.% CO and 1 vol.% CH 4 .

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“…Thus, treatment of benzaldehyde, ethyl acetoacetate and urea in the presence of the silver salt of 12-tungustophosphoric acid [14] in water at 80°C resulted in the formation of 4-phenyl-3,4-dihydropyrimidinone in 92% yield (Scheme 1).…”

Section: Resultsmentioning

confidence: 97%

“…The catalyst was prepared according to the procedure reported in literature. [14] General Procedure: A mixture of aldehyde (5 mmol), ethyl acetoacetate (5 mmol), urea (10 mmol), and Ag 3 PW 12 O 40 (10% w/w of aldehyde) in water or ethanol (10 mL) was stirred at 80°C for the appropriate time (Table 1). On completion of the reaction, as indicated by TLC, the reaction mixture was lyophilized to remove the water.…”

Section: Resultsmentioning

confidence: 99%

Green Protocol for the Biginelli Three‐Component Reaction: Ag₃PW₁₂O₄₀ as a Novel, Water‐Tolerant Heteropolyacid for the Synthesis of 3,4‐Dihydropyrimidinones

et al. 2004

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Biginelli three-component condensation of an aldehyde, β-keto ester, and urea proceeds smoothly on the surface of the silver salt of heteropolyacid (HPA), i.e. Ag 3 PW 12 O 40 , in water to afford the corresponding 3,4-dihydropyrimidinones in high-to-quantitative yields under mild conditions. The heterogeneous solid acid provides ease of separation of the catalyst and isolation of the products. The recovered catalyst can be recycled in subsequent reactions with consistent activity.

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Potassium and Silver Salts of Tungstophosphoric Acid as Catalysts in Dehydration of Ethanol and Hydration of Ethylene

Cited by 113 publications

References 24 publications

Silver nanowires as a result of irradiation or hydrogen reduction of Ag₃PW₁₂O₄₀ salt

Silver nanowires as a result of irradiation or hydrogen reduction of Ag₃PW₁₂O₄₀ salt

Analysis and optimisation of H2 production from crude glycerol by steam reforming using a novel two step process

Green Protocol for the Biginelli Three‐Component Reaction: Ag₃PW₁₂O₄₀ as a Novel, Water‐Tolerant Heteropolyacid for the Synthesis of 3,4‐Dihydropyrimidinones

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Potassium and Silver Salts of Tungstophosphoric Acid as Catalysts in Dehydration of Ethanol and Hydration of Ethylene

Cited by 113 publications

References 24 publications

Silver nanowires as a result of irradiation or hydrogen reduction of Ag3PW12O40 salt

Silver nanowires as a result of irradiation or hydrogen reduction of Ag3PW12O40 salt

Analysis and optimisation of H2 production from crude glycerol by steam reforming using a novel two step process

Green Protocol for the Biginelli Three‐Component Reaction: Ag3PW12O40 as a Novel, Water‐Tolerant Heteropolyacid for the Synthesis of 3,4‐Dihydropyrimidinones

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Silver nanowires as a result of irradiation or hydrogen reduction of Ag₃PW₁₂O₄₀ salt

Silver nanowires as a result of irradiation or hydrogen reduction of Ag₃PW₁₂O₄₀ salt

Green Protocol for the Biginelli Three‐Component Reaction: Ag₃PW₁₂O₄₀ as a Novel, Water‐Tolerant Heteropolyacid for the Synthesis of 3,4‐Dihydropyrimidinones