简介:Anewreaction-controlledphase-transfercatalystsystem,lacunaryKegginpolyoxotungstate[C7H7N(CH3)3]9PW9O34hasbeensynthesizedandusedforcatalyticepoxidationofolefinswithH2O2astheoxidant.Infraredspectrawereusedtoanalyzethebehaviorofthephasetransferofcatalyst.Inthissystem,thecatalystnotonlycanactashomogeneouscatalystbutalsoasheterogeneouscatalysttobeeasilyfilteredandreused.Theepoxidarionreactioniscleanandexhibitshighconversionandselectivityaswellasexcellentcatalyststability.
简介:ThecatalyticperformanceofCs-substitutedphosphomolybdicsaltswasstudiedforselectiveoxidationofisobutane.Theresultsofactivitytestsrevealedthat360°Cwastheoptimalreactiontemperature.Itwasdemonstratedthatoxidizingsitesnotonlytookdominatingpartintheactivationofisobutane,butalsoinfluencedtheproductdistribution.Besides,appropriateCsadditionledtomoderateacidityofcatalysts,favoringtheselectivitytodesiredproducts.Furthermore,toobtainpartiallyreducedcatalysts,differentcalcinationatmosphereswereinvestigatedandcertainproportionofMo~(5+)producedduringcalcinationwascrucialfortheredoxreaction.ThecatalystcalcinedinN_2showedthehighestyieldofMAA(7.0%).Fe-substitutionenhancedtheactivityofcatalystsbyrapidreoxidationofMo~(5+).
简介:Fouriertransformedinfraredspectrometry(FTIR)and27AlMagicAnglespinning(MAS)nuclearmagneticresonancespectroscopywereemployedtocharacterizearsenateadsorptiononamorphousAlgelswithKegginstructureatpH=4–10.Thesestudieshaveproventhat:thesurfacecomplexspeciesofarsenateshowsignificantdifferencesunderacidicandalkalineconditions,whichwasdeducedbasedontheAs-Ostretchingvibrationbandslocatedrespectivelyat774and870cm-1;poorlycrystallineAl13(orAl)-arsenateprecipitationcouldbeeasilyformedunderacidmediumconditionandhighloadinglevel,whichwassupportedbycomparingtheAs-Ovibration(at≈732cm-1)ofprecipitationtoadsorbedAlgels;arsenate(AsO43-)adsorptionhasnoeffectontheKegginstructureofAlgelswithbasicity(R)=2.6and3.0,evenathighloadinglevel,asevidencedbythesignalat≈63×10-6ofmagicanglespinning(MAS)-27AlNMR.Theadsorptionenvelopewasdeterminedbyconventionalbatchexperiments.
简介:利用水热合成方法合成了2个新的苯并咪唑修饰的Keggin型多酸基化合物[(C_7H_6N_2)_3(H_3PMo_(12)O_(40))]·H_2O(1)和[KNa_2(C_7H_5N_2)_2(H_(2.5)SiW_(12)O_(40))_2]·6(C_7H_6N_2)(2)(C_7H_6N_2=苯并咪唑).化合物1为超分子结构,化合物2为2种碱金属钾和钠与多酸配位形成链状多酸基化合物,并通过元素分析和X-射线单晶衍射方法确定了2种化合物的晶体结构.单晶结构分析表明化合物1属于三斜晶系,P-1空间群,晶胞参数a=1.1580(7)nm,b=1.3159(8)nm,c=1.8254(12)nm,α=84.418(10)°,β=88.958(10)°,γ=65.852(10)°,V=2.5255(3)nm3,Z=2;化合物2也属于三斜晶系,P-1空间群,晶胞参数a=1.3586(9)nm,b=1.4403(10)nm,c=1.8365(13)nm,α=109.509(10)°,β=90.755(10)°,γ=114.864(10)°,V=3.0236(4)nm3,Z=1.
简介:合成了三价态过渡金属取代的钨硅杂多配合物αSiW11Mx-(M=MnⅢ、FeⅢ、CoⅢ)的K(或Cs)盐,通过元素分析、红外、紫外、可见光谱、循环伏安等手段进行了表征.研究了配合物的热稳定性、水溶液中的酸碱稳定性、催化活性以及磁性,常温和变温(82K~272K)磁化率数据表明配合物具有顺磁性特征.
简介:选用新颖的有机配体3-噻吩-5-三氟甲基-2,3-二氢-1-H吡唑(L),在水热条件下成功得到2个新的基于Keggin多酸的超分子化合物,{[Ag(L)_2]_3[PMo_(12)O_(40)]}·3H_2O(1)和{[Ag(L)_2]_3[HSiMo_(12)O_(40)]}·3H_2O(2).通过红外光谱、元素分析和单晶X-射线对化合物1和2的结构进行了表征.化合物1和2同构,包含1个孤立的Keggin多阴离子和3个金属-有机亚单元[Ag(L)2]+.其中多酸阴离子和[Ag(L)2]+片段通过氢键作用力交替连接形成1个一维超分子链.相邻一维链进一步通过氢键连接成二维超分子层状结构.光催化和电化学性质表明,化合物1和2具有相同的电化学性能.