Keggin type heteropolyacids-catalyzed synthesis of quinoxaline derivatives in water

Keggin type heteropolyacids was found to be an efficient and reusable catalyst for the synthesis of biologically active quinoxaline derivatives from the condensation of 1,2-diamine with 1,2-dicarbonyl compounds in excellent yields in water. This method provides a new and efficient protocol in terms of small quantity of catalyst, a wide scope of substrates, and simple work-up procedure.

Preparation of the Supported Heteropolyacids Catalyst by Ultrasound-plasma Treatment

Novel catalysts of phosphotungstic heteropolyacids （PW12） supported on neutral alumina were prepared by assistance of ultrasound and plasma treatment. The prepared catalysts were characterized by FT-IR pyridine adsorption （Py-IR）, temperature programmed desorption of Pyridine （Py-TPD）, BET and X-ray diffraction （XRD）, and their catalytic performances were evaluated by the cationic polymerization of tetrahydrofuran. The results indicate that plasma treatment remarkably increases the surface acidity of the prepared catalyst while ultrasonic treatment induces PW12 to uniformly disperse on the support surface and expose more active sites for the acid catalytic reaction. A higher catalytic activity （69.7%） is obtained on the novel catalyst, which significantly outstripped that on the conventional sample （57.5%）.

Heteropolyacids-Immobilized Graphitic Carbon Nitride:Highly Efficient Photo-Oxidation of Benzyl Alcohol in the Aqueous Phase

Benzaldehyde is a highly desirable chemical due to its extensive application in medicine,chemical synthesis and food sector among others.However,its production generally involves hazardous solvents such as trifluorotoluene or acetonitrile,and its conversion,especially selectivity in the aqueous phase,is still not up to expectations.Hence,developing an environmentally benign,synthetic process for benzaldehyde production is of paramount importance.Herein,we report the preparation of a photocatalyst(PW_(12)-P-UCNS,where PW_(12)is H3PW_(12)O_(40)xH_(2)O and P-UCNS is phosphoric acid-modified unstack graphitic carbon nitride)by incorporating phosphotungstic acid on phosphoric acid-functionalised graphitic carbon nitride(g-C_(3)N_(4))nanosheets.The performance of PW_(12)-P-UCNS was tested using the benzyl alcohol photo-oxidation reaction to produce benzaldehyde in H_(2)O,at room temperature(20℃).The asprepared PW12-P-UCNS photocatalyst showed excellent photocatalytic performance with 58.3%conversion and 99.5%selectivity within 2 h.Moreover,the catalyst could be reused for at least five times without significant activity loss.Most importantly,a proposed Z-scheme mechanism of the PW_(12)-P-UCNScatalysed model reaction was revealed.We carefully investigated its transient photocurrent and electrochemical impedance,and identified superoxide radicals and photogenerated holes as the main active species through electron spin-resonance spectroscopy and scavenger experiments.Results show that the designed PW_(12)-P-UCNS photocatalyst is a highly promising candidate for benzaldehyde production through the photo-oxidation reaction in aqueous phase,under mild conditions.

Etherification of Methanol with Propylene Oxide Catalyzed by Heteropolyacids

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Heteropolyacids Catalysis in Synthesizing Butylacrylate

The catalytic activities of some heteropolyacids(HPAs) in synthesizing butyl acrylate are reported. It has been demonstrated that 12 tungstophosphoric acid is the most effective catalyst among more than 20 HPA(salts). Various factors concerned in this reaction have been investigated. The optimum conditions have been found, that is, the molar ratio of alcohol to acid is 1.2∶1.0 , the catalyst concentration 1%(mass fraction), the reaction time 2 h, the temperature 98—124 ℃ and a certain amount of polymerization inhibitor exists.

One-Pot Process of Naphthoquinones Synthesis from Hydroquinone in the Presence of Solutions of Mo-V-P Heteropolyacids as Bifunctional Catalysts

1,4-Naphthoquinones (NQ) is a class of organic compounds with a number of important properties. However, the existing methods of their synthesis either give a low NQ yield or multistage and require a lot of time. In the present work new one-pot process of NQ synthesis from hydroquinone (HQ) and substituted 1,3-dienes at room temperature is proposed. The solution of heteropolyacid H7PMo8V4O40 (HPA-4) is used as a bifunctional (acid and redox) catalyst for this process. The influence of a number of factors on key process parameters has been studied. It is demonstrated that unsubstituted and a number of alkyl substituted NQ with the yields of 50% - 80% and purity of 92% - 99% can be obtained by this method. The results obtained allow to significantly simplify the synthesis of NQ directly from HQ in comparison with the described similar methods.

Coupling biomass pretreatment for enzymatic hydrolysis and direct biomass-to-electricity conversion with molybdovanadophosphoric heteropolyacids as anode electron transfer carriers

Owing to their acidity,oxidizing ability and redox reversibility,molybdovanadophosphoric heteropolyacids(H_(n+3)PMo_(12-n)VnO40,abbreviated as PMo_(12-n)Vn) were employed as electron transfer carriers for coupling biomass pretreatment for enzymatic hydrolysis and direct biomass-to-electricity conversion.In this novel coupled process,PMo_(12-n)Vn pretreatment that causes deconstruction of cell wall structure with PMo_(12-n)Vn being simultaneously reduced can be considered as the "charging" process.The reduced PMo_(12-n)Vn are further re-oxidized with release of electrons in a liquid flow fuel cell(LFFC) to generate electricity is the "discharging" process.Several Keggin-type PMo_(12-n)Vn with different degree of vanadium substitution(DSV, namely n) were prepared.Compared to Keggin-type phosphomolybdic acid(PMo_(12)),PMo_(12-n)Vn(n=1-6) showed higher oxidizing ability but poorer redox reversibility.The cellulose enzymatic digestibility of PMo_(12-n)Vn pretreated wheat straw generally decreased with increase in DSV, but xylan enzymatic digestibility generally increased with DSV.PMo_(12) pretreatment of wheat straw at 120℃ obtained the highest enzymatic glucan conversion(EGC) reaching 95%,followed by PMo11V1 pretreatment(85%).Discharging of the reduced heteropolyacids in LFFC showed that vanadium substitution could improve the maximum output power density(Pmax).The highest Pmax was obtained by PMo9 V3(44.7 mW/cm^(2)) when FeCl_(3) was used as a cathode electron carrier,while PMo_(12) achieved the lowest Pmax(27.4 mW/cm^(2)).All the heteropolyacids showed good electrode Faraday efficiency(>95%) and cell discharging efficiency(>93%).The energy efficiency of the coupled process based on the heat values of the products and generated electric energy was in the range of 18%-25% depending on DSV.PMo_(12) and PMo11V1 seem to be the most suitable heteropolyacids to mediate the coupled process.

三个基于Wells-Dawson型多酸的三核铜簇的合成、结构及性能

在水热条件下，通过Wells—Dawson型多酸[As2W18O62]^6-、氯化铜（CuCl2·2H2O）和5-（4-毗啶基）-1H-四氮唑（4-ptz）的反应，在同一反应釜中合成出2个结构完全不同的、都包含三核铜簇的多酸基化合物[Cu3（4-ptz）4（H2O）7（As2W18O62）]·42H2O（1）和[Cu3（4-ptz），（H2O）5（As2W18O62）]·47H2O（2）；当我们以另一种Wells—Dawson型多酸[P2W18O62]^6-、氯化铜（CuCl2·2H2O）和5-（3-吡啶基）-1H-四氮唑（3-ptz）反应，获得了另一种多酸基三核铜簇化合物[Cu3（3-ptz）4（H2O）8（P2W18O62）]·33H2O（3）。X射线单晶衍射结果表明，化合物1为多酸单支撑三核铜簇的悬臂式结构，化合物2的多阴离子被三核铜簇交替连接形成一维链式结构．而化合物3为多阴离子和三核铜簇形成的孤立结构。吡啶-四氮唑类配体（3-ptz和4-ptz）是形成化合物1～3中三核铜簇的重要结构因素。同时，研究了3个化合物的电化学以及光催化性能．

Nano-porous Composites Based on Liquid： Synthesis, Characterization, Esterification Heteropolyacid Functionalized Ionic and Catalytic Performance in

Fhnctionalized ionic liquid samples （bmim-PW12） were synthesized by 1-butyl-3-methyl- imidazolium bromide （bmimBr） and 12-phosphotungstic heteropolyacid （PW12）. The samples were annealed at 100-450 ℃ and were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, thermal gravity-DTG, brunauer emmett teller, and NHa-temperature programmed desorption. The results showed that the bmim-PW12 samples were crystal and maintained intact Keggin structure. The organic parts of those samples were partly decomposed at a temperature more than 350 ℃. The sample annealed at 400 ℃ exhibited nano-porous structure, strong acidity, and excellent catalytic activity on the esterification of n-butanol with acetic acid. The higher ester yield was obtained when the mass ratio of catalyst over the reactants amount was 5% for bmim-PW12 catalyst annealed at 400 ℃.

Tungstophosphoric heteropolyacid supported onto neutral alumina: characterization and synthesis of acetals and ketals

Tungstophosphoric acid （HPW） catalyst supported on the neural alumina was studied. It was prepared by means of an equilibrium and incipient wetness impregnation technique. Solution of HPW in 50% V/V ethanol-water was used to impregnate Al2O3 at 25℃. It was found that the catalyst containing 30% PW by calcination at 500℃ showed a higher catalytic activity in the synthesis of acetals and/or ketals. In the following condition, that is, the molar ratio of aldehyde/ketone to glycol being 1：1.5, the mass fraction of the catalyst used was 0.5%, and the reaction time was 1.0 h; the yields of ketals and acetals could reach up to 60.5%-86.7%. Moreover, it could be easily recovered and reused.

Synthesis of ethyl acetate by esterification of acetic acid with ethanol over a heteropolyacid on montmorillonite K10

In present work,liquid phase esterification of acetic acid with ethanol over dodecatungestophosphoric acid （DTPA） supported on K10 montmorillonite was systematically studied and optimization of process parameters was carried out.The 20% m/m DTPA/K10 was found to be the optimum catalyst with 90% acetic acid conversion and 100% ethyl acetate selectivity.The study was also explored to see the feasibility of 20% m/m DTPA/K10 as a catalyst for the alkylation of acetic acid with other alcohols like methanol,iso-propanol and n-butanol.The 20% m/m DTPA/K10 has shown increased activity with the increase in carbon number,at the same alcohol reflux.The results are novel.

A kinetic model for a single step biodiesel production from a high free fatty acid (FFA) biodiesel feedstock over a solid heteropolyacid catalyst

Production of biodiesel from yellow grease(waste cooking oil and waste animal fats) is fast emerging as a promising alternative to address the twin challenges before the biodiesel industry today-fluctuation in prices of vegetable oil and the food versus fuel debate. Yellow grease has a high percentage of free fatty acids(FFA) and proves to be an unsuitable feedstock for biodiesel production from commercially viable alkalicatalyzed production systems due to saponification problems.'Green' methodologies based on heterogeneous solid acid catalyzed reactions have the potential to simultaneously promote esterification and transesterification reactions of yellow grease to produce biodiesel without soap formation and offer easy catalyst separation without generation of toxic streams. This paper presents kinetic studies for the conversion of model yellow grease feeds to biodiesel using a heteropolyacid supported on alumina(HSiW/Al2O3) using a batch autoclave. Three model yellow grease feeds were prepared using canola oil with added FFA such as palmitic, oleic and linoleic acid. A pseudo homogeneous kinetic model for the parallel esterification and transesterification was developed. The rate constants and activation parameters for esterification and transesterification reactions for the model yellow grease feeds were determined. The rate constants for esterification are higher than the transesterification rate constants. The kinetic model was validated using the experimental biodiesel data obtained from processing a commercial yellow grease feed. The kinetic model could be used to design novel processes to convert various low-value waste oils, fats and non-food grade oils to sustainable biodiesel.

A Novel Synthesis of Polyaniline Doped with Heteropolyacid and its Special Property

Polyaniline doped with heteropolyacid was synthesized using solid-state synthesis method. XRD pattern showed that polyaniline molecule has highly ordered arrangement. Fluorescence property of the polyaniline materials was found.

一例Wells-Dawson型铌钨混配多酸的合成及光催化性能（英文）

在双氧水存在条件下,合成了一例Wells-Dawson型铌钨混配多酸K3.5Na4[H4.5(NbO2)6P2W12O5 6]·12.5H2O(1),X射线单晶结构分析表明,化合物1的多阴离子是一个六过氧铌基团取代的P2W12衍生物.六个铌原子分别与五个来自多酸框架上的氧原子和一个端位的过氧单元配位.另外,对化合物1的光催化产氢性能进行了初步研究.

High dispersion of heteropolyacid nanoparticles on hydrothermally Cs-modified three-dimensionally ordered macroporous SiO2 with excellent selectivity in methacrolein oxidation

Heteropolyacid nanoparticles(NPs)were supported on Cs-modified three-dimensionally ordered macroporous(3DOM)SiO2 and used as the catalyst for the oxidation of methacrolein(MAL)to methacrylic acid(MAA).Hydrothermal treatment and incipient wetness impregnation were employed respectively for the Cs-modification.It was found that hydrothermal Cs-modification of 3DOM SiO2 promoted the dispersion of the supported heteropolyacid,which showed an average particle size of 5.2 nm,much smaller than that(17.6 nm)on the Csmodified 3DOM SiO2 prepared by incipient wetness impregnation.The effects of hydrothermal treatment on the structure and catalytic performance of the catalyst were investigated.Results showed that the ion exchange between Cs+and the surface silanol groups on 3DOM SiO2 was promoted with the increase of the hydrothermal temperature.Meanwhile,Cs-modification helped the heteropolyacid to retain intact Keggin structure,inhibiting the formation of MoO3.Highly dispersed heteropolyacid NPs with enhanced structural stability exhibited excellent selectivity to MAA in the oxidation of MAL.

一个基于Wells-Dawson型多金属氧酸盐的有机-无机化合物的合成与结构

以夹心结构Wells-Dawson型化合物[Na16P4W30Cu4(H2O)2O112](简写为{Cu4P4W30})作为无机构筑块,有机含氮化合物吡嗪(简写为Pz)和过渡金属Co(II)离子分别作为桥连配体和节点金属,在常压水溶液中合成了一个结构新颖的有机-无机杂化化合物(H3O)4[{Co6(H2O)22(Pz)2}{Cu3Co(H2O)2P4W30O112}].19H2O,并通过X-射线单晶衍射测定该化合物的晶体结构。标题化合物属三斜晶系,P-1空间群,晶胞参数:a=1.4323(2)nm,b=1.4539(3)nm,c=2.0794(2)nm,V=4.126(2)nm3,Z=1,F(000)=4126,R1=0.1230,wR2=0.2597。结构分析表明,Wells-Dawson型杂多酸阴离子作为一个八齿配体,在a、b方向上分别通过桥氧和[Co2(Pz)(H2O)8]4+配阳离子、Co(II)向外延伸连接成为一个具有二维网络状结构的有机-无机聚合物。此外,还通过元素分析、IR和TG等手段对化合物进行了相应的性质表征。

Hydroxylation of Benzene to Phenol by H_2O_2 over an Inorganic–Organic Dual Modified Heteropolyacid

Various catalysts, including the heteropolyacid(HPA) H4PMo11VO40, its cesium salts, and inorganic–organic dual modified HPA catalyst, were prepared and characterized by Fourier transform infrared spectroscopy(FT-IR), nuclear magnetic resonance(13C NMR), N2 adsorption, acid–base titration, electron spin resonance(ESR) and X-ray diffraction(XRD) techniques as well as elemental analysis. These prepared catalysts were used in the hydroxylation of benzene to phenol by H2O2 as oxidant. The inorganic–organic dual modified HPA Cs2.5(MIMPS)1.5PMo11VO40, prepared by partially exchanging Cs+with protons in H4PMo11VO40 and followed by the immobilization of 3-(1-methylimidazolium-3-yl)propane-1-sulfonate(MIMPS), led to a liquid–solid biphasic catalysis system in the hydroxylation, which showed the best catalytic performance in terms of reusability and catalytic activity. The high reusability of Cs2.5(MIMPS)1.5PMo11VO40 in the heterogeneous hydroxylation was probably due to its high resistance in leaching of bulk HPA into the reaction medium. The slightly enhanced catalytic activity for the catalyst was due to the acid sites available from MIMPS beneficial to the hydroxylation.

Hydrothermal Synthesis and Characterization of a Novel Organically-templated Tungsten Heteropolyacid with a Microporous Structure

A microporous organically-templated tungsten heteropolyacid, (C2N2H10)2 [H2P2W18O62]?8H2O, with a new type was hydrothermally synthesized by using ethylenediamine as the structure-directing agent. Its structure was determined by single-crystal X-ray diffraction analysis. Crystal data: monoclinic, space group P21/c, a = 14.633(4), b = 19.432(5), c = 26.776(5) ?, β = 117.849(11)o, V = 6732(3) ?3, Z = 4, Mr = 4615.48, Dc = 4.554 g/cm3, μ(MoKα) = 30.781 mm-1, F(000) = 7976, the final R = 0.0678 and wR = 0.1359. The crystal of the title compound is constructed by Dawson anions and organic dications forming a novel “hollow” channel system.

离子液体多酸在燃油氧化脱硫中的研究进展

氧化脱硫,因其反应条件温和、成本较低等特点被广泛应用于燃油脱硫领域。近年来,有研究者发现离子液体中的阴阳离子结构具有可调性,可借此通过物理化学法制备出高效的催化剂,为更深度的氧化脱硫提供有利条件。本文总结了离子液体多酸的合成与分类,详细叙述了单纯离子液体多酸和以金属有机框架或无机非金属材料为载体的负载型离子液体多酸的特点以及目前其在燃油氧化脱硫领域的研究进展,包括脱硫率和重复使用次数等脱硫效果。单纯离子液体多酸的初次脱硫效率都在80%以上,最高可达99.2%,而负载后的离子液体多酸的脱硫率都在98%以上,大多数高达100%,重复利用次数最高可达13次。众多研究者一致认为负载型离子液体多酸不仅能有效增强多酸的催化活性,而且可提高催化剂的热稳定性与重复利用性,在燃油氧化脱硫中有着良好的使用效果。最后对离子液体多酸在氧化脱硫领域的发展方向提出了展望,指出了具有良好催化性能、可重复利用性好、绿色高效的离子液体多酸是未来的研究方向,为进一步研究离子液体多酸提供了参考。