Catalytic conversions in water. Part 5: Carbonylation of 1-(4-isobutylphenyl)ethanol to ibuprofen catalysed by water-soluble palladium–phosphine complexes in a two-phase system

1-(4-Isobutylphenyl)ethanol (IBPE) was carbonylated to 2-(4-isobutylphenyl)propionic acid (ibuprofen) in an aqueous/organic two phase system using the water-soluble Pd(tppts)₃ catalyst [tppts = P(C₆H₄-m-SO₃Na)₃] in the presence of p-CH₃C₆H₄SO₃H at 363 K, 15 MPa CO pressure and a palladium concentration of 150 ppm without addition of organic solvents. Under these conditions the conversion of IBPE was 83% and the selectivity to ibuprofen 82% with no decomposition of the Pd(tppts)₃ catalyst. Both the activity and selectivity were strongly influenced by the tppts/Pd molar ratio and the nature of the added Brønsted acid. Maximum efficiency was observed for P/Pd = 10. Acids of weakly or non-coordinating anions, such as p-CH₃C₆H₄SO₃H, CF₃COOH or HPF₆ afforded carbonylation. No catalytic activity was observed in the presence of acids of strongly coordinating anions, such as HI. The water-soluble Pd/dppps catalyst [dppps = Ar_2-nPh_nP-(CH₂)₃-PPh_n′Ar_2-n′; Ar = C₆H₄-m-SO₃Na; n = nń = 0: 86% and n = 0, nń = 1: 14%] exhibited low catalytic activity and the major product obtained was the linear isomer of ibuprofen, 3-(4-isobutylphenyl)propionic acid (3-IPPA) with selectivities up to 78%. Replacement of tppts by a ligand containing less −SO₃Na groups such as monosulphonated triphenylphosphine (tppms) gives rise to a dramatic drop in the catalytic activity and selectivity to ibuprofen. No catalytic activity was observed using palladium catalysts modified with 2-pyridyldiphenylphosphine (PyPPh₂) and tris(2-pyridyl)phosphine (PPy₃) which are both water soluble in their protonated form. A catalytic cycle is proposed to explain the observed results. ©1997 SCI     

Palladium(0) allylic alkylation in a two-phase system or with a supported aqueous phase catalyst

The reaction of allylic carbonates with various acyclic and cyclic carbonucleophiles is catalyzed by the system Pd(OAc)₂ and P(C₆H₄-m-SO₃Na)₃ (or tppts) in a two-phase liquid medium H₂O-nitrile, the activity of the catalyst depending mainly on the nature of the nitrile, the temperature of the reaction and the ratio palladium/tppts. The same system Pd(OAc)₂ and P(C₆H₄-m-SO₃Na)₃ supported on silica catalyzes also this reaction. The formation of the active palladium species in the two cases is followed by

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NMR spectroscopy and discussed.     

Ce在负载Pd催化苯酚氧化羰基化合成碳酸二苯酯反应中的作用

采用微乳液法制备了Ce为助剂的Pd-Ce-O/SiO₂催化剂,用于苯酚氧化羰基化合成碳酸二苯酯（DPC）反应。活性评价结果显示,催化剂性能随着Ce用量的增加而提高,当Ce/Pd摩尔比为10/1时,苯酚转化率为64.4%,碳酸二苯酯选择性为83.4%。利用XRD表征发现,部分Ce⁴⁺进入到PdO晶格中,使得失活Pd原子中的电子更容易向Ce转移,从而易于再生,表现出更好的催化性能。根据上述结果,设计制备了Pd-O/CeO₂催化剂用于本反应,苯酚转化率和碳酸二苯酯选择性分别仅为24.0%和23.3%。表征发现,在Pd-Ce-O/SiO₂催化剂表面,Pd物种主要是PdO,而Pd-O/CeO₂表面的Pd物种则以PdO₂为主。由于苯酚氧化羰基化反应的活性中心为Pd(Ⅱ),所以Pd-O/CeO₂催化性能较差。并且,由于Pd与CeO₂之间存在强相互作用,催化剂表面Pd含量较低,这也是Pd-O/CeO₂催化活性较差的原因之一。     

Selective catalytic reduction of N2O and NOx in a single reactor in the nitric acid industry

The nitric acid industry is a source of both NO_x and N₂O. The simultaneous selective catalytic reduction of both compounds using propane as a reductant has been investigated. A stacked catalyst bed with first a Co-ZSM-5 catalyst and second a Pd/Fe-ZSM-5 catalyst gives >80% conversion of N₂O and NO_x above 300 °C at atmospheric pressure. At 4 bar absolute pressure (bara) the Co-ZSM-5 DeNO_x catalyst shows higher NO_x and propane conversion. This leaves not enough propane for the Pd/Fe-ZSM-5 DeN₂O catalyst, which causes a ‘dip’ in N₂O conversion. Reducing the space velocity (SV) of the first catalyst bed secures high NO_x and N₂O conversions from 300 °C and up at 4 bara.     

丁腈橡胶催化加氢反应研究

氢化丁腈橡胶具有良好的耐油性和耐氧性,广泛应用于汽车和石油行业,通过丁腈橡胶溶液均相催化加氢制得,采用铑类和钯类均相催化剂。考察不同溶剂、催化剂及m(Ru)∶m(丁腈橡胶)对丁腈橡胶加氢的影响。采用红外光谱法和核磁法对氢化丁腈橡胶的结构进行分析,筛选出价廉、活性高和选择性高的催化剂。结果表明,在丁腈橡胶加氢反应中,丁酮可作为溶剂,Ru(PPh3)3Cl2催化剂具有高活性和高选择性。在丁酮200 m L、丁腈橡胶5 g、Ru(PPh3)3Cl2催化剂、m(Ru)∶m(丁腈橡胶)=0.000 20∶1、反应温度140℃、氢压8.0 MPa和反应时间4 h条件下,加氢度和选择性均达到100%,具有与Rh(PPh3)3Cl相当的催化性能。     

Cr2O3/SiO2催化苯酚与碳酸二乙酯邻位烷基化反应

以Cr(NO₃)₃?9H₂O为前体,采用等体积浸渍法制备了一系列不同Cr₂O₃负载量的Cr₂O₃/SiO₂催化剂;在固定床连续微反装置上,考察了Cr₂O₃/SiO₂催化剂对苯酚与碳酸二乙酯邻位烷基化反应的催化性能;采用XRD、NH₃-TPD、CO₂-TPD和吡啶吸附、红外等手段对催化剂进行了表征。实验结果表明,随着Cr₂O₃负载量的增加,苯酚的转化率和邻乙基苯酚的选择性均逐渐增加;当Cr₂O₃负载量达到7.5%时,苯酚的转化率和邻乙基苯酚的选择性均达到最大值,分别为48%和67%。催化剂的表征结果表明,L酸中心是苯酚邻位烷基化反应的活性中心,苯酚转化率和邻乙基苯酚选择性的变化主要是由催化剂的酸、碱中心数目变化引起的。     

Hydrogen production by oxidative methanol reforming on Pd/ZnO: Catalyst preparation and supporting materials

Pd and Pd–Zn alloy were supported on various supporting materials using impregnation, co-precipitation and microemulsion methods, and their catalytic performances in oxidative methanol reforming (OMR) were investigated. Pd/ZnO exhibited much higher selectivity than either Pd/Al₂O₃ or Pd/ZrO₂ in the OMR for hydrogen production. This was attributed to the presence of Pd–Zn alloy on the ZnO support. Elemental Pd on Al₂O₃ or ZrO₂ promotes methanol decomposition reaction and increases CO formation. Using a microemulsion method, a highly selective Pd/ZnO can be obtained with much lower Pd loading than that in samples prepared by co-precipitation. Modification of Al₂O₃ with ZnO produced a ZnAl₂O₄ phase, which was found to be a good support for the Pd/ZnO catalyst. Highly active and selective Pd/ZnO/ZnAl₂O₄ catalysts for the OMR reaction, containing much lower Pd loadings have been developed by impregnation of the supports with an aqueous solution of Pd(NO₃)₂ + Zn(NO₃)₂.     

Epoxidation of propylene by using [π-C5H5NC16H33]3[PW4O16] as catalyst and with hydrogen peroxide generated by 2-ethylanthrahydroquinone and molecular oxygen

The epoxidation of propylene catalyzed by a reaction-controlled phase transfer catalyst [π-C₅H₅NC₁₆H₃₃]₃[PW₄O₁₆] is investigated. The H₂O₂ is generated by the oxidation of 2-ethylanthrahydroquinone (EAHQ) with molecular oxygen in the organic solvent. Under mild conditions, the selectivity for propylene oxide, based on propylene, is 95%, and the yield, based on 2-ethylanthrahydroquinone, is 85%. During the epoxidation, the catalytic system is homogeneous. However, after the H₂O₂ is used up, the catalyst can be recovered as a precipitate and can be reused. After the epoxidation reaction, 2-ethylanthraquinone can be regenerated to 2-ethylanthrahydroquinone by catalytic hydrogenation, and no coproduct is produced.     

Micellar catalysis for partial oxidation of toluene to benzoic acid in supercritical CO2: effects of fluorinated surfactants

One of the key hindrances on development of solid catalysts containing cobalt species for partial oxidation of organic molecules at mild conditions in conventional liquid phase is the severe metal leaching. The leached soluble Co species with a higher degree of freedom always out-performs those of solid supported Co species in oxidation catalysis. However, the homogeneous Co species concomitantly introduces separation problems. We have recently reported for the first time, a new oxidation catalyst system for the oxidation of organic molecules in supercritical CO₂ using the principle of micellar catalysis. [CF₃(CF₂)₈COO]₂Co·xH₂O (the fluorinated anionic moiety forms aqueous reverse micelles carrying water-soluble Co²⁺ cations in scCO₂) was previously shown to be extremely active for the oxidation of toluene in the presence of sodium bromide in water–CO₂ mixture, giving 98% conversion and 99% selectivity to benzoic acid at 120 °C. In this study, we show that the effects of varying the type of surfactant counterions and the length of the surfactant chains on catalysis. It is found that the use of [CF₃(CF₂)₈COO]₂Mg·yH₂O/Co(II) acetate is as effective as the [CF₃(CF₂)₈COO]₂Co·xH₂O and the fluorinated chain length used has a subtle effect on the catalytic rate measured. It is also demonstrated that this new type of micellar catalyst in scCO₂ can be easily separated via CO₂ depressurisation and be reused without noticeable deactivation.     

不同载体负载Pd双功能催化剂制备及其液相甲醇催化一步合成甲酸甲酯

以γ-Al_2O_3、ZrO_2、Bentonite(膨润土)、MIL-53(Al)和MIL-53(Fe)为载体,采用浸渍法制备负载Pd双功能催化剂,利用XRD、BET和NH3-TPD等表征催化剂结构,在微型高压反应器中评价催化剂的液相甲醇一步催化转化合成甲酸甲酯的反应性能,考察反应条件对催化剂性能的影响。结果表明,不同载体负载Pd催化剂未观察到Pd的XRD特征峰,表明催化剂表面的Pd是高分散状态。不同载体负载Pd催化剂的比表面积、酸强度和酸量差别较大,并且酸强度和酸量对甲醇转化率和产物选择性有较大影响。具有较多中强酸的2%Pd/Bentonite、2%Pd/MIL-53(Al)和2%Pd/MIL-53(Fe)催化剂比中强酸较少的2%Pd/γ-Al_2O_3和2%Pd/ZrO_2催化剂具有更高的甲醇转化率和甲酸甲酯选择性。2%Pd/Bentonite催化剂在每摩尔甲醇Pd用量为0. 030 mmol、反应温度150℃、O_2压力2 MPa和反应时间5 h条件下,液相甲醇一步催化转化合成甲酸甲酯反应中,甲醇转化率56. 08%,甲酸甲酯选择性55. 85%。     

Methanol decomposition to synthesis gas at low temperature over palladium supported on ceria–zirconia solid solutions

The Ce_xZr_1−xO₂ solid solution was used as a support of a palladium catalyst for methanol decomposition to synthesis gas at low temperature. All Pd-containing catalysts tested in this study showed high selectivity to synthesis gas (over 96%). The Pd supported on the composite oxide with a Ce/Zr molar ratio of 4/1 exhibited the highest activity. Pd/Ce_0.8Zr_0.2O₂ (17 wt.%) (cop) (prepared by coprecipitation method) showed a conversion of 51.2% for the methanol decomposition at 473 K, which was higher than those over 17 wt.% Pd/CeO₂ (cop) (40.7%) and 17 wt.% Pd/ZrO₂ (cop) (24.3%) at 473 K. The 17 wt.% Pd/Ce_0.8Zr_0.2O₂ (cop) catalyst showed a higher BET surface area and smaller Pd particles than those of 17 wt.% Pd/CeO₂ (cop). Moreover, a more active Pd^σ+ state could be maintained by Zr⁴⁺ ion modification due to promotion of the oxygen mobility and enhancement of the reductibility and increase in the acid sites of the CeO₂ support. The 17 wt.% Pd/Ce_0.8Zr_0.2O₂ (cop) catalyst showed a much higher conversion (51.2%) than that over 17 wt.% Pd/Ce_0.8Zr_0.2O₂ (imp) (prepared by impregnation method) (17.2%) at 473 K. This is due to the 17 wt.% Pd/Ce_0.8Zr_0.2O₂ (cop) possessing many small Pd particles. The 17 wt.% Pd/Ce_0.8Zr_0.2O₂ (cop) catalyst showed an initial conversion of 51.2% at 473 K but the conversion decreased to 43.1% after 24 h on stream. This deactivation was attributed to carbonaceous deposit on the catalyst surface. The amounts of coke on the 17 wt.% Pd/Ce_0.8Zr_0.2O₂ (cop) catalyst were 0.9 wt.% after 24 h on stream at 473 K and 2.1 wt.% after 1 h on stream at 523 K.     

溶剂热浸渍法制备高稳定性Zn(OAc)2/SiO2催化剂及其催化合成苯氨基甲酸甲酯

Zn(OAc)₂对由碳酸二甲酯（DMC）和苯胺合成苯氨基甲酸甲酯（MPC）的反应具有优异的催化性能,但存在易失活、不能重复使用的缺点。为此,以DMC为溶剂,利用溶剂热浸渍法制备Zn(OAc)₂/SiO₂催化剂,并对其催化性能进行了研究。利用XRD、FTIR和TG-DTA等方法对其进行了表征,结果表明,Zn(OAc)₂/SiO₂催化剂表面存在Zn(OAc)₂和ZnO,且其在SiO₂表面分散较好;优化了Zn(OAc)₂/SiO₂催化剂的反应条件,当反应温度为190℃、反应时间为5h、苯胺与DMC的摩尔比为1∶20、催化剂与苯胺质量比为0.2时,苯胺的转化率为97.2%,MPC的选择性为89.4%。和等体积浸渍法制备的催化剂相比,溶剂热浸渍法制备的Zn(OAc)₂/SiO₂催化剂具有较好的稳定性,重复使用7次,苯胺的转化率下降至79.1%,MPC的选择性下降至79.2%。Zn(OAc)₂/SiO₂活性下降的原因是由于ZnO的生成,并对其进行了再生,再生后的催化剂活性与新鲜催化剂接近。     

Pt/TiO_2催化二甲醚部分氧化重整制氢

二甲醚是一种理想的氢载体,可用于解决氢的储存和运输。以Pt/TiO_2为部分氧化催化剂,结合Ni/Al_2O_3重整催化剂,考察钛前驱体和焙烧温度对二甲醚部分氧化重整制氢反应的影响。结果表明,以Ti(C4H9O)4为原料制备的TiO_2为金红石相,Ti(SO4)2或Ti O(OH)2为原料制备的TiO_2为锐钛矿相;以Ti(C4H9O)4为原料制备的Pt/TiO_2-E催化剂催化性能略好,转化率接近100%,H2收率约90%,表明金红石相TiO_2负载的Pt催化剂略佳;以Ti(SO4)2为原料制备的Pt/TiO_2-S催化剂500℃焙烧可获得金红石相TiO_2。与Pt/Al_2O_3催化剂相比,Pt/TiO_2催化剂具有更好的催化性能,H2收率超过90%,而Pt/Al_2O_3催化剂H2收率约80%。     

Screening of amorphous metal–phosphate catalysts for the oxidative dehydrogenation of ethylbenzene to styrene

The gas-phase oxidative dehydrogenation of ethylbenzene to styrene was carried out by using as catalyst a series of metal phosphates (Al, Fe, Ni, Ca and Mn) and stoichiometric (Al/Fe = Al/Ca = 1) mixed systems: FeAl(PO₄)₂ and Ca₃Al₃(PO₄)₅, that were prepared by an ammonia gelation method. Their amorphous character was determined through several physical methods: nitrogen adsorption, DRIFT and XRD patterns. These results were compared to those obtained with 24 commercial inorganic solids (several metal oxides, sulfates and phosphates). Reactions were also carried out without oxygen, under non-oxidative conditions, where the catalytic activity was always appreciably lower than under oxidative conditions. Experimental results indicated that the oxidative gas-phase dehydrogenation of ethylbenzene to styrene could be related to the total number of acid and basic sites of catalysts, so that this reaction probably needs selected acid–basic pairs for coke formation, where the oxidative dehydrogenation process is developed.

The main practical conclusion of the catalyst screening was that the best results were obtained with the synthesized amorphous AlPO₄, where 43% ethylbenzene conversion and 99.7% styrene selectivity were achieved. A very reduced number of commercial inorganic solids like Al₂(SO₄)₃, Cr₂(SO₄)₃, Fe₂(SO₄)₃, NiSO₄, Al₂O₃ and Fe₂O₃ were also able to obtain an acceptable catalytic behavior, with conversions ranging between 18 and 23% and selectivity in the 95–100% range. Among the other synthesized solids, Ni₃(PO₄)₂-A-450 was the only metal phosphate exhibiting results in such a range. All the other catalysts studied were rather inactive and/or selective. Additional experiments carried out at longer times on stream (3.5 h) and longer contact times (W/F 0.254 and 0.654) confirmed the superior catalytic behavior of amorphous AlPO₄. Consequently, this solid could be a good candidate for application as a catalyst in the industrial oxydehydrogenation of ethylbenzene to styrene.     

Relationship between structural/surface characteristics and reactivity in n-butane oxidation to maleic anhydride: The role of V species

V/P/O-based catalysts were prepared by thermal treatments of VOHPO₄0·5H₂O precursors prepared with the organic procedure. Different methods for precursor dehydration led to compounds which were characterized by the prevailing presence of crystalline (VO)₂P₂O₇, but which also contained either V⁵⁺ species or V³⁺ species. The catalytic performance of these compounds in n-butane oxidation under almost-equilibrated conditions was compared. It was found that the presence of either V³⁺ or V⁵⁺ enhances the specific activity in n-butane oxidation, while the selectivity to maleic anhydride at low n-butane conversion (30%) remains substantially unaffected. A fully equilibrated, well-crystallized (VO)₂P₂O₇ was reduced with H₂. The reduced compound was more active than the fully equilibrated vanadyl pyrophosphate, while exhibiting comparable selectivity to maleic anhydride.     

氮杂环卡宾-钯功能化的配位聚合物（NHC-Pd@Zn-L）：合成、表征及催化Suzuki-Miyaura交叉偶联反应

以\mathrm{1,3}-二(1-羧乙基)咪唑盐(HL)和Zn(NO₃)₂·6H₂O反应合成二维配位聚合物[Zn(L)₂] _n (Zn-L)，产物再与K₂PdCl₄在四氢呋喃溶液中反应引入氮杂环卡宾-钯（NHC-Pd）催化位点，制得催化剂NHC-Pd@Zn-L，并通过PXRD、TGA、ICP、SEM、EDS和XPS进行表征。结果表明，NHC-Pd@Zn-L具有良好的热稳定性且修饰后晶体的框架结构没有发生变化，Pd以NHC-Pd的形式结合在Zn-L中，并均匀分散在配位聚合物中。将NHC-Pd@Zn-L用于催化Suzuki-Miyaura交叉偶联反应，当以苯硼酸和溴苯为底物，催化剂用量为15 mg，乙醇为溶剂，碳酸钾为碱的条件下60℃反应6 h，产率达到>99%，而且催化剂易于回收并可循环使用3次。     

氮杂环卡宾-钯功能化的配位聚合物（NHC-Pd@Zn-L）：合成、表征及催化Suzuki-Miyaura交叉偶联反应

以\mathrm{1,3}-二(1-羧乙基)咪唑盐(HL)和Zn(NO₃)₂·6H₂O反应合成二维配位聚合物[Zn(L)₂] _n (Zn-L),产物再与K₂PdCl₄在四氢呋喃溶液中反应引入氮杂环卡宾-钯（NHC-Pd）催化位点,制得催化剂NHC-Pd@Zn-L,并通过PXRD、TGA、ICP、SEM、EDS和XPS进行表征。结果表明,NHC-Pd@Zn-L具有良好的热稳定性且修饰后晶体的框架结构没有发生变化,Pd以NHC-Pd的形式结合在Zn-L中,并均匀分散在配位聚合物中。将NHC-Pd@Zn-L用于催化Suzuki-Miyaura交叉偶联反应,当以苯硼酸和溴苯为底物,催化剂用量为15 mg,乙醇为溶剂,碳酸钾为碱的条件下60℃反应6 h,产率达到>99%,而且催化剂易于回收并可循环使用3次。     

An efficient green route for hexamethylene-1,6-diisocyanate synthesis by thermal decomposition of hexamethylene-1,6-dicarbamate over Co3O4/ZSM-5 catalyst:An indirect utilization of CO2

The utilization of CO2 as rawmaterial for chemical synthesis has the potential for substantial economic and green benefits. Thermal decomposition of hexamethylene-1,6-dicarbamate (HDC) is a promising approach for indirect utilization of CO2 to produce hexamethylene-1,6-diisocyanate (HDI). In this work, a green route was developed for the synthesis of HDI by thermal decomposition of HDC over Co3O4/ZSM-5 catalyst, using chlorobenzene as lowboiling point solvent. Different metal oxide supported catalysts were prepared by incipientwetness impregnation (IWI), PEG-additive (PEG) and deposition precipitation with ammonia evaporation (DP) methods. Their catalytic performances for the thermal decomposition of HDC were tested. The catalyst screening results showed that Co3O4/ZSM-525 catalysts prepared by different methods showed different performances in the order of Co3O4/ZSM-525(PEG) N Co3O4/ZSM-525(IWI) N Co3O4/ZSM-525(DP). The physicochemical properties of Co3O4/ZSM- 525 catalyst were characterized by XRD, FTIR, N2 adsorption-desorption measurements, NH3-TPD and XPS. The superior catalytic performance of Co3O4/ZSM-525(PEG) catalyst was attributed to its relative surface content of Co3+, surface lattice oxygen content and total acidity. Under the optimized reaction conditions: 6.5% HDC concentration in chlorobenzene, 1 wt% Co3O4/ZSM-525(PEG) catalyst, 250 °C temperature, 2.5 h time, 800 ml·min?1 nitrogen flow rate and 1.0 MPa pressure, the HDC conversion and HDI yield could reach 100% and 92.8% respectively. The Co3O4/ZSM-525(PEG) catalyst could be facilely separated from the reaction mixture, and reused without degradation in catalytic performance. Furthermore, a possible reaction mechanism was proposed based on the physicochemical properties of the Co3O4/ZSM-525 catalysts.     

氮化碳负载钯催化剂的制备及对SBS选择性催化加氢性能的研究

苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)选择性催化加氢是保留链段中苯环不被加氢而C C双键选择性加氢,从而得到具有更优异性能的高附加值氢化产物SEBS。为了消除反应物大分子孔内扩散限制问题,采用胶体SiO₂亚微米球为模板,通过氰胺热缩合成功合成了三维有序超大孔氮化碳(3DOM g-C₃N₄),以其为载体采用化学还原负载法得到了具有超大孔结构的Pd/3DOM g-C₃N₄催化剂,并将其用于SBS的选择性催化加氢反应。结果表明,Pd/3DOM g-C₃N₄催化剂具有超大孔-大孔-介孔多级孔三维贯穿结构且Pd颗粒尺寸小、分散均匀,该催化剂在较为温和的反应条件下,即表现出极为优异的加氢活性和选择性。根据红外表征计算得到其对SBS的1,2-C C和1,4-C C总加氢度达到98%,而对苯环没有加氢,选择性为100%。其优异的催化性能主要归功于载体独特的超大孔-大孔-介孔多级孔三维贯穿结构可以有效消除大分子在孔隙中的扩散限制,从而提高了对活性位...     

Effects of iron precursors on the structure and catalytic performance of iron molybdate prepared by mechanochemical route for methanol to formaldehyde

Mechanochemical synthesis has been applied for many novel material preparations and gained more and more attention due to green and high-efficiency recently. In order to explore the influences of iron precursors on structure and performance of iron molybdate catalyst prepared by mechanochemical route, three typical and cheap iron precursors have been used in preparation of iron molybdate catalyst. Many characterization methods have been employed to obtain the physical and chemical properties of iron molybdate catalyst. Results indicate that iron precursors have the significant impact on the phase composition, crystal morphology and catalytic performance in the conversion of methanol to formaldehyde. It is hard to regulate the phase composition by changing Mo/Fe mole ratios for Fe_2(SO_4)_3 as iron precursor. In addition, as for Fe_2(SO_4)_3, the formaldehyde yield is lower than that from iron molybdate catalyst prepared with Fe(NO_3)_3·9H_2O due to the reduction in Fe_2(MoO_4)_3 phase as active phase. Based on mechanochemical and coprecipitation method, the solvent water could be a key factor for the formation of MoO_3 and Fe_2(MoO_4) for FeCl_3·6H_2O and Fe_2(SO_4)_3 as precursors. Iron molybdate catalyst prepared with Fe(NO_3)_3·9H_2O by mechanochemical route, shows the best methanol conversion and formaldehyde yield in this reaction.