Heteropoly Salt Research Articles

Selective separation and immobilization process of 137Cs from high-level liquid waste based on silicon-based heteropoly salt and natural minerals

• Silicon-based composite adsorbent was effective for 137 Cs removal. • The interaction mechanism of Cs was studied at the molecular level by density functional theory. • A conceptual process for separation and long-term safe disposal of Cs was proposed. A macro porous silica-based ammonium phosphomolybdate (AMP/SiO 2 ) adsorbent was synthesized and tested for separation and recovery of 137 Cs from real radioactive liquid waste. The excellent adsorption ability and high selectivity of AMP/SiO 2 for 137 Cs were confirmed. AMP/SiO 2 had relatively large decontamination efficiency of 137 Cs exceeding 99% in radioactive wastes, and the decontamination factors of 137 Cs were estimated to be 688 and 270 after adsorption in radioactive waste at 1 and 3 mol/L HNO 3 , respectively. In column operation, the separation and recovery of Cs(I) and coexisting ions could be realized using different eluents, and the recovery rate of Cs(I) was more than 90%. The Cs 3d and Mo 3d X-ray photoelectron spectroscopic spectra of AMP/SiO 2 before and after Cs(I) adsorption, suggesting that the ion exchange process of cesium with crystal lattice cations was the governing mechanism, and cesium ions could spontaneously react with approximately two ammonium ions in each AMP lattice by density functional theory simulation. Further, the crystal binding energy of each revised model showed an upward trend with the progress of the adsorption. After sintering at 1200 °C, CsAlSiO 4 , which could stably solidify eluted cesium, was formed in the allophane-based solidified product. The crystalline properties and volume reduction effect of the sintered products were enhanced with the increase in the allophane content. Ba(II) hardly entered the lattice of CsAlSiO 4 and occupied the Cs(I) site, resulting in minor changes in the crystal structure with substitution of Ba(II) for Cs(I).

Hydrodeoxygenation of 2,5-dimethyltetrahydrofuran over bifunctional metal-acid catalyst Pt–Cs2.5H0.5PW12O40 in the gas phase: Kinetics and mechanism

• DMTHF deoxygenated to hexane with >99% selectivity at 90–100 °C and ambient pressure. • Bifunctional Pt–CsPW catalyst much more efficient than monofunctional pt. • HDO occurs via hydrogenolysis, dehydration and hydrogenation steps on pt and H + sites. • Hydrogenolysis of furan ring on pt is a structure-sensitive reaction. Hydrodeoxygenation (HDO) of 2,5-dimethyltetrahydrofuran (DMTHF) was studied at a gas-solid interface in a fixed-bed microreactor in the presence of bifunctional metal-acid catalysts comprising Pt/C and acidic heteropoly salt Cs 2.5 H 0.5 PW 12 O 40 (CsPW). The Pt–CsPW catalyst deoxygenated DMTHF to n-hexane with >99% selectivity under mild conditions (90–100 °C, ambient pressure) and was much more efficient than monofunctional Pt/C. On the basis of kinetic studies, a mechanism for the HDO of DMTHF over Pt–CsPW was proposed, which includes a sequence of hydrogenolysis, dehydration and hydrogenation steps catalysed by Pt and proton sites of the bifunctional catalyst. The turnover rate of HDO increased with increasing Pt particle size suggesting that the hydrogenolysis of C–O bond in furanic compounds on Pt is a structure-sensitive reaction.

NIR-driven upconversion nanophotocatalyst based on hybrid inorganic-organic polyoxometalate for photodegradation of liquorice and biologically treated yeast extract industrial wastewater

Utilization of Near-infrared (NIR) or infrared light improve the efficiency of photodegradation by using lower energy but it has remained as a challenge yet. NIR light-driven nanocomposite containing organic heteropoly salt and TiO2 has been synthesized by a two-step sol-gel/solvothermal method to extend the absorption range of the TiO2 photocatalyst from UV to IR region. This photoactivity was proved by Tauc and photoluminescence plots. This compound has been well-characterized by XRD, SEM-EDX, PL, FTIR and EIS techniques. The composite structure can not only extend the absorption of TiO2 but also consequently increase life-time of excited electron and hole, which improve the photocatalytic efficiency of the photocatalyst. The charge transfer resistance was also decreased compare with TiO2 which was proved by Nyquist and Bode plots. Photocurrent generation was studied by photoelectrochemical investigation. Photodegradation of liqourice and biologically treated yeast extracted wastewater were also investigated with optimization of reaction conditions. The present work should be the rarely fundamental investigation on the utilization of NIR light-driven photocatalyst.

Study on the Synthesize, Characterization, and Conductive Performance of Nickelzircomolybdnum Heteropoly Acid Salt with Keggin Structure

A novel heteropoly acid salt, Na6[Ni(Mo11ZrO39)]·20H2O, has been synthesized by the means of acidification and adding the reactants into the solution step by step. The heteropoly compound was characterized by elemental analysis, TGA/DSC, infrared spectrum, ultraviolet spectrum, X-ray diffraction, and SEM. Its protonic conduction was measured by the means of the electrochemical impedance spectrum. The results showed that it belongs to the Keggin type, and its conductivity value was 1.23 × 10–2 S/cm at 23°C when the relative humidity was 60%, and the conductivity enhanced with the elevated temperature. Its proton conduction mechanism was in accordance with vehicle mechanism, and the activation energy was 27.82 kJ/mol.

Glycerol Esterification over Sn(II)-Exchanged Keggin Heteropoly Salt Catalysts: Effect of Thermal Treatment Temperature

In this work, Sn(II)-exchanged Keggin heteropoly acid salts were evaluated as solid catalysts in glycerol esterification reactions with acetic acid. All the Sn(II) heteropoly salts and their precur...

Tin(II) phosphotungstate heteropoly salt: An efficient solid catalyst to synthesize bioadditives ethers from glycerol

In this work, the activity of Sn(II)-Keggin heteropolyacid salts (i.e., Sn3/2PW12O40 and Sn3/2PMo12O40) was investigated on the etherification reactions of glycerol with tert-butyl alcohol. Tin(II) heteropoly catalysts were easily synthesized and characterized by analyses of FT-IR/ATR, TG/DSC, MEV/EDS, XRD, BET, and potentiometric titration with n-butylamine. The activity of heteropoly salts was compared to the precursor heteropolyacids and SnSO4 catalysts. The Sn3/2PW12O40-catalyzed etherification achieved the highest tert-butyl glycerol ethers selectivity (ca. 90%) after 4 h of reaction at 363 K. The selectivity toward mono-glyceryl tert-butyl ether (i.e., an efficient surfactant) or di-tert-butyl glyceryl ether (i.e., a fuel bioadditive) can be tailored by an adequate adjustment of the reaction parameters (i.e., catalyst loading, reactant stoichiometry). Glycerol ethers were characterized by 1H and 13C NMR and infrared spectroscopy and mass spectrometry.

Ultrasonic Degradation Performance of the CeZrMo Heteropoly Salt with Keggin Structure

A new heteropoly salt with Keggin structure of the 1:1:11 series had been synthesized, and characterized the structure by the foruier transform infrared spectroscopy (IR), ultraviolet spectra (UV) and X-ray diffraction (XRD).The thermal stability and the number of the crystal water was analyzed by the thermal gravimetric analysis/differential thermal analysis (TG/DTA). It was showed the molecular formula was Na5[Ce(ZrMo11O39)]•16H2O( Abbrev.CeZrMo),it possessed Keggin structure and had good thermal stability. The influences on the degradation rate, such as the amount of the CeZrMo, the initial concentration of the AGB dye wastewater, the ultrasonic frequency and power, were investigated. The results showed that the degradation rate could reach 88.01% after 60min irradiation, when the amount of the CeZrMo was 0.8g•L-1, the concentration of the AGB was 10mg•L-1, the ultrasonic frequency was 45kHz and the ultrasonic power was 100W.

Ultrasonic Degradation Performance of the NiZrMo Heteropoly Salt with Keggin Structure

A new heteropoly salt with Keggin structure of the 1:1:11 series had been synthesized, and characterized the structure by the foruier transform infrared spectroscopy (IR), ultraviolet spectra (UV) and X-ray diffraction (XRD).The thermal stability and the number of the crystal water was analyzed by the thermal gravimetric analysis/differential thermal analysis (TG/DTA). It was showed the molecular formula was Na6[Ni(ZrMo11O39)]•20H2O( Abbrev.NiZrMo),it possessed Keggin structure and had good thermal stability. The influences on the degradation rate, such as the amount of the NiZrMo, the initial concentration of the AGB dye wastewater, the ultrasonic frequency and power, were investigated. The results showed that the degradation rate could reach 90.19% after 60min irradiation, when the amount of the NiZrMo was 0.8g•L-1, the concentration of the AGB was 10mg•L-1, the ultrasonic frequency was 40kHz and the ultrasonic power was 80W.

Study on Synthesis, Characterization and Ultrasonic Degradation the Dyeing Wastewater of 11- MnZrMo Heteropoly Salt with Keggin Structure

The heteropoly salt, Na6[Mn(Mo11ZrO39)] •19H2O（MnZrMo）with Keggin structure of the 1:1:11series, was synthesized by the aqueous solution method, and characterized and analyzed. The element analysis showed that the molar ratio of Mn, Zr and Mo was accord with 1:1:11;the thermogravimetric analysis/ differential thermal analysis(TG/DTA) indicated that the MnZrMo had good thermal stability and it contained nineteen molecules of crystallization water; the characterization of the fourier transform infrared spectroscopy(FT-IR),X-ray powder diffraction analysis(XRD) and the ultraviolet spectrum(UV) showed that the anionic of the MnZrMo heteropoly salt possessed Keggin structure; the analysis of the scanning electron microscopy(SEM) showed that it had the basic feature of the macromolecular compound and a regular crystal. The MnZrMo heteropoly salt was used as the catalyst to degrade the acidic-green B(AGB) dyeing wastewater enhanced by the ultrasonic, the degradation rate could reach 95.90%.

Efficient hydrodeoxygenation of biomass-derived ketones over bifunctional Pt-polyoxometalate catalyst

Acidic heteropoly salt Cs(2.5)H(0.5)PW(12)O(40) doped with Pt nanoparticles is a highly active and selective catalyst for one-step hydrogenation of methyl isobutyl and diisobutyl ketones to the corresponding alkanes in the gas phase at 100 °C with 97-99% yield via metal-acid bifunctional catalysis.

Study on Synthesis, Characterization and Photocatalytic Property of FeZrMo Heteropoly Salt with Keggin Structure

A new heteropoly salt with Keggin structure of the 1:1:11 series has been synthesized by the aqueous solution method, and structurally characterized by SEM, TG/DTA,IR,UV and XRD. The results from the experiment showed that the molar ratio of Fe, Zr and Mo accord with 1:1:11, the molecular formula was Na5[Fe(ZrMo11O39)]•19H2O( Abbrev.FeZrMo),it possessed Keggin structure and had good thermostability. The heteropoly salt was used as the catalyst to degrade the acidic-green B(Abbrev. AGB) dye wastewater, the degradation rate could reach 84.49%.

PERANAN KATALIS K3-xHxPW12O40 PADA KATALISIS SELEKTIF SINTESIS METILAMINA DARI METANOL DAN AMONIAK

Role of K3-xHxPW12O40 as a Catalyst in Selective Catalysis of Methylamine Synthesis from Ammonia andMethanol. Synthesize of methylamine from methanol and ammonia was studied in this research work using a partiallypotassium heteropoly salt (K3-xHxPW12O40 abbreviated as KPW) as a catalyst. KPW was prepared from heteropoly saltand potassium carbonate by using ion exchange method. The reaction was conducted at 600 ~ 800K and at theatmospheric pressure. Reactor used was a continue flow reactor with W/F=0,1~0,9g-kat.mnt./cc.Concentration ofreactants and products were analyzed by gas chromathography while catalyst structure was observed by XRD (X-raydiffraction). Isothermal adsorption method was used for determining catalyst pore size. The result showed that ionexchange between H ion in zeolit with K ion produced potassium heteropoly salt that caused the change of interstitialspace. The change of interstitial space was observed by the change of the lattice constant of the catalyst crystal.Trimethylamine(TMA) has molecule size smaller than catalyst pore size but bigger than molecular size ofDimethylamine (DMA) and Monimethylamine (MMA). This phenomenon caused the suppression of TMA formation.KPW has a rigid crystal structure and stabil during reaction. On the other hand, crystal structure of a non selectivecatalyst (NH4)3PW12O40 was not rigid and its pore size is easy to change depending on the product molecule size.

Hydrogenolysis of Glycerol to Propanediol Over Ru: Polyoxometalate Bifunctional Catalyst

Ruthenium-doped (5 wt%) acidic heteropoly salt Cs2.5H0.5(PW12O40) (CsPW) is an active bifunctional catalyst for the one-pot hydrogenolysis of glycerol to 1,2- propanediol (1,2-PDO) in liquid phase, providing 96% selectivity to 1,2-PDO at 21% glycerol conversion at 150 � C and an unprecedented low hydrogen pressure of 5 bar. Rhodium catalyst, 5%Rh/CsPW, although less active, shows considerable selectivity to 1,3-PDO (7.1%), with 1,2-PDO being the main product (65%).

Fries rearrangement of phenyl acetate catalysed by platinum-doped heteropoly salt: Catalyst regeneration and reuse

The acidic cesium hetetropoly salt Cs 2.5H 0.5PW 12O 40 (CsPW) is an active solid acid catalyst for the liquid-phase Fries rearrangement of phenyl acetate, which, similar to other solid acid catalysts, suffers from deactivation due to coke deposition. Coke burning cannot effectively regenerate CsPW because of its relatively low thermal stability. Doping CsPW with Pt metal (0.3 wt%) allows full regeneration of catalyst activity and selectivity by the aerobic oxidation of coke at 350 °C and ambient pressure, which occurs without any structural damage to the catalyst. Pt doping practically does not affect the activity and selectivity of CsPW. As a coke-burning catalyst, Pt is much more efficient than Pd; the latter requires almost ten times higher a metal loading. The Pt/CsPW catalyst is characterised by XRD, TGA/TPO, FTIR and H 2 chemisorption.

Efficient Acylation of Toluene and Anisole with Aliphatic Carboxylic Acids Catalyzed by Heteropoly Salt Cs2.5H0.5PW12O40.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Efficient acylation of toluene and anisole with aliphatic carboxylic acids catalysed by heteropoly salt Cs2.5H0.5PW12O40

Heteropoly salt Cs2.5H0.5PW12O40 is a highly efficient and reusable solid acid catalyst for the liquid-phase acylation of toluene or anisole with C2 – C12 aliphatic carboxylic acids.

Characterization of the compounds formed from the interaction of divalent cations with inorganic molecular metal—oxygen cluster compounds

Infrared spectroscopy, powder X-ray diffraction, differential thermal analysis and nitrogen adsorption—desorption measurements were carried out on a series of solids prepared from 12-molybdophosphoric and 12-tungstophosphoric acids and the alkaline earth hydroxides. A single crystal investigation and data analysis were done for the Ba 2+ /PMo 12O 40 3− system. It is concluded that the reaction of simple divalent salts with 12-molybdophosphoric acid produces a mixture of the parent acid and a divalent compound rather than a divalent heteropoly salt.

Alkylation of toluene with methanol over heteropoly acid/Y-zeolite catalysts

Alkylation of toluene with methanol has been studied in a fixed bed reactor with a continuous flow system. As a promoter, heteropoly acids and their metal salts were impregnated on Y-zeolite. Catalyst impregnated with lower amount of heteropoly acid showed higher initial activity, and the catalytic activity was enhanced by more electronegative metal ion of heteropoly acid salt impregnated on Y-zeolite, Catalyst calcined at lower temperature showed higher initial activity, but its deactivation rate was faster than that calcined at higher temperature. Catalyst impregnated with BiPMo12O40 showed a good activity and a good regeneration ability of catalytic activity.

A Highly Specific Method of Separating Cesium by Ion Exchange on Thallous Phosphotungstate.

Thallous phosphctungstate (TPT) is a highly specific cation exchanger for cesium. The heteropoly salt is converted into a form suitable for column use by mixing with paper pulp. The affinity of several monovalent ions for the exchanger is in the order Cs >> Ag > Rb > K. A simple method for obtaining essentially quantitatively a cesium fraction of high purity from virtually any starting solution is based on absorption on TPT, washing with 0.005M thallous nitrate which removes contaminants, and eluting cesium with 0.15M thallous nitrate. A major advantage over other methods using synthetic rnorganic exchangers is that the final cesium fraction is obtained free of ammonium ion, a frequently used eluent which is troublesome to remove. The column retention capacity of TPT rs 0.5, 0.3, and 0.1 meq per gram for cesium, rubidium, and potassium, respectively. (auth)