Synthesis of Ga-incorporated SAPO-34s (GaAPSO-34) and their catalytic performance on methanol conversion

This study has been focused on the synthesis of GaAPSO-34s substituted gallium for aluminum in order to improve the acidic property in SAPO-34 crystal. As the result, GaAPSO-34s with various Al/Ga ratios (Al/Ga=∞, 40, 20, 10, 5, and 0) were successfully synthesized. These were characterized by XRD, SEM, ICP, TG-DTA, MAS-NMR, and BET surface areas. The crystallinity identified from the intensity of XRD peak (for angles of 22.5° and 9.7°) and the particle size observed from SEM photographs decreased with an increase in the Ga content incorporated into the SAPO-34 framework. On the other hand, decrease in the acid sites in crystal as a target in this study was confirmed in the Ga-incorporated samples. In particular, a surprising result was that the selectivity to ethylene on methanol conversion increased in catalyst with Al/Ga=20 compared with pure SAPO-34 catalyst. However, in spite of the decreases in acid sites and particle size in catalyst with much more Ga content, the selectivity to ethylene was not enhanced, rather the methane which related to catalytic deactivation increased in GaAPSO-34 catalysts. This is ascribed to collapses of framework of SAPO-34 with an increase in Ga content.     

Synthesis and catalytic performance on methanol conversion of NiAPSO-34 crystals (I): effect of preparation factors on the gel formation

In order to synthesize the NiAPSO-34 crystal with a pure CHA structure having a uniform size and stable catalytic activity, factors having influence on the crystallization at gel preparation were investigated. The results showed that the mixing order of starting materials influences on the crystallization rate. The concentration of the template was related to the morphology of crystals and the crystallinity, while the particle size obtained was controlled by the silica source and the amount of nickel. Moreover, it was elucidated that the mixing orders of starting materials influences on the crystal growth rate. Seed crystal addition (SAPO-34; 0.8 μm) and ultrasonic-wave treatment after the gel formation were effective in decreasing smaller particle size and in narrowing the size distribution.     

Methanol conversion on metal-incorporated SAPO-34s (MeAPSO-34s)

The influence on metal incorporation into the framework of SAPO-34 (MeAPSO-34) on methanol conversion was investigated in this study. Used MeAPSO-34s (SAPO-34, FeAPSO-34, CoAPSO-34, and NiAPSO-34) were acquired by the rapid crystallization method. In characteristics, it was identified that these catalysts had a uniformly regular form with a sharp distribution in particle size. The performances on methanol conversion for these catalysts were different according to the properties of metals. As a result, the methanol conversion was enhanced on the metal-incorporated catalyst compared with the non-metal catalyst. In reaction at 450°C for 1 h, the order of increasing in ethylene selectivity was followed as next; Ni->Co->Fe->non-metal-incorporated SAPO-34. On the other hand, the selectivity for all the samples decreased with an increase in reaction time, however, the reduced rate was very slow on CoAPSO-34 compared with the other catalysts. In addition as a surprising result, the CoAPSO-34 catalyst exhibited a minor methanation.     

SAPO-35分子筛的合成及其甲醇制烯烃反应性能

以六亚甲基亚胺为模板剂,采用水热法合成了不同硅含量的磷酸硅铝分子筛SAPO-35,并利用X射线衍射、X射线荧光光谱、扫描电镜、固体核磁、X射线光电子能谱和N₂吸附-脱附等方法对样品进行了表征.研究了不同硅含量的SAPO-35分子筛在甲醇转化制烯烃反应中的催化行为,同时对比分析了具有相近硅含量的SAPO-35和SAPO-34分子筛在甲醇转化反应过程中积炭物种随反应时间的演变特征,尝试将分子筛结构和其积炭失活行为进行了关联.     

以正丁胺为模板剂合成SAPO-34及其在氨甲基化反应中的应用

以正丁胺为模板剂首次合成了纯相的SAPO-34分子筛.考察了硅投料量、硅源种类以及晶化温度等条件对所得样品性质的影响.发现反应温度为200°C时,不加入硅源,合成产物为磷酸铝层状相kanemite;加入硅溶胶后,产物中开始有SAPO-34晶体出现,且随着硅投料量的增加,kanemite逐渐消失,SAPO-34分子筛成为主要产物,最终在SiO2/Al2O3摩尔比为0.6-1.4时得到纯相的SAPO-34.不同的硅源对SAPO-34产品的形貌和尺寸影响较大.反应温度为160°C时,合成体系中无法晶化得到SAPO-34,当提高至240°C后,由于层状相在高温下不能稳定存在,此时可以在较宽的硅投料区间内合成得到纯相SAPO-34产品.在200和240°C时,考察了使用同样的初始凝胶合成SAPO-34样品的晶化过程.发现在200°C时,合成体系中最初大量生成了kanemite,随后逐渐减少,SAPO-34晶体开始生成并最终成为唯一产物.而在240°C时,无机原料很快被溶解,之后大量的SAPO-34晶体快速生成,产物的收率和相对结晶度迅速增加,且整个晶化过程中并无层状相生成.这再次证明了高温对层状相的生成有着明显的抑制作用,因此提高晶化温度可以成为一种有效调节产品晶相的方法,特别是在容易产生层状相杂质的合成体系中.鉴于胺热合成方法的诸多优点,例如较高的收率、较好的吸附分离及催化反应效果,几种伯胺(正丁胺、正丙胺、环己胺)被用于充当模板剂和溶剂来合成得到了SAPO分子筛产品.其中,正丙胺为一种新的合成SAPO-34的模板剂.对SAPO-34产品进行X射线衍射、X射线荧光分析、扫描电镜、N2物理吸附、NH3程序升温脱附、热重和固体核磁共振等表征.结果显示,得到的SAPO-34产品具有很好的结晶度、孔结构以及合适的酸性.使用氨甲基化反应对正丁胺合成的SAPO-34进行催化反应评价.结果显示,该样品对甲胺和二甲胺具有很高的择形选择性,是一种具有潜在前景的甲胺合成催化剂.     

Fabrication of hierarchical ZnSAPO-34 by alkali treatment with improved catalytic performance in the methanol-to-olefin reaction

A series of hierarchical ZnSAPO-34 zeolites were synthesized by treatment with different concentrations of tetraethylammonium hydroxide (TEAOH) solutions. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), temperature-programmed desorption, Fourier transform infrared, and N₂ adsorption and desorption techniques and studied as catalysts for the methanol to olefin reaction. The characterization results reveal that the crystal size of ZnSAPO-34 is greatly reduced compared with the parent SAPO-34 owing to the incorporation of Zn. Hierarchical pores with the sizes up to the macropore level in the ZnSAPO-34 zeolites are created with the post-treatment of TEAOH. The acid strength and the amounts of the strong acid of the hierarchical ZnSAPO-34 zeolites decrease after the post-treatment because TEAOH preferentially extracts Si species from the zeolite. The hierarchical ZnSAPO-34 zeolites exhibit superior catalytic performance than that of the parent ZnSAPO-34, owing to the shortened transportation distance and the appropriate acidity of the treated samples.     

Parent-amido (NH2) palladium(II) complexes: Synthesis,reactions, and catalytic hydroamination

The treatment of [PdL₃(NH₃)](OTf)_n (n = 1; L₃ = (PEt₃)₂(Ph), (2,6-(Cy₂PCH₂)₂C₆H₃), n = 2; L₃ = (dppe)(NH₃)) with NaNH₂ in tetrahydrofuran at ambient temperature or −78 °C afforded the dimeric and monomeric parent-amido palladium(II) complexes anti-[Pd(PEt₃)(Ph)(μ-NH₂)]₂ (1), [Pd(dppe)(μ-NH₂)]₂(OTf)₂ (2), and Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(NH₂) (3), respectively. The molecular structures of the amido-bridged (μ-NH₂) dimeric complexes 1 and 2 were determined by single-crystal X-ray crystallography. The monomeric amido complex 3 reacted with trace amounts of water to give a hydroxo complex, Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(OH) (4). Exposing complex 3 to an excess of water resulted in the complete conversion of the complex into two species [Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(OH₂)]⁺ and [Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(NH₃)]⁺. Complex 3 reacted with diphenyliodonium triflate ([Ph₂I]OTf) to give the aniline complex [Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(NH₂Ph)]OTf. The reaction of 3 with phenylacetylene (HCCPh) yielded a palladium(II) acetylenide Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(CCPh) (5), quantitatively, along with the liberation of ammonia. The reaction of 3 with dialkyl acetylenedicarboxylate yielded diastereospecific palladium(II) vinyl derivatives (Z)-Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(CRCR(NH₂)) (R = CO₂Me (6a), CO₂Et (6b)). The reaction of complexes 6a and 6b with p-nitrophenol produced Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(OC₆H₄-p-NO₂) (7) and cis-CHRCR(NH₂), exclusively. Reactions of 3 with either dialkyl maleate (cis-(CO₂R)CHCH(CO₂R)) (R = CH₃, CH₂CH₃) or cis-stilbene (cis-CHPhCHPh) did not result in any addition product. Instead, isomerization of the cis-isomers to the trans-isomers occurred in the presence of catalytic amounts of 3. Complex 3 reacted with a stoichiometric amount of acrylonitrile (CH₂CHCN) to generate a metastable insertion product, Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(CH(CN)CH₂NH₂). On the other hand, the reaction of 3 with an excess of acrylonitrile slowly produced polymeric species of acrylonitrile. The catalytic hydroamination of olefins with NH₃ was examined in the presence of Pd(2,6-(Cy₂PCH₂)₂C₆H₃)(OTf), producing a range of hydroaminated products of primary, secondary, and tertiary amines with different molar ratios of more than 99% overall yield. A mechanistic feature for the observed catalytic hydroamination is described with regard to the aminated derivatives of palladium(II).     

ZSM-5分子筛的粒径可控合成及其在甲醇转化中的催化作用

以四丙基氢氧化胺为模板剂、聚乙二醇为添加剂,水热合成了粒径在0.1～14 μm且分布均一的ZSM-5分子筛,并采用XRD、SEM、BET、Py-IR、NH₃-TPD和ICP等技术对其进行了表征,考察了不同粒径分子筛在甲醇转化制碳氢化合物反应中的催化作用。结果表明,通过调变PEG添加量、硅源种类和水含量以及控制陈化和晶化条件,可以在较大范围内调变分子筛晶粒尺寸。随着粒径的减小,ZSM-5晶粒的聚集程度、比表面积和Si/Al比提高,而结晶度、BrØnsted酸浓度和总酸量有所下降。在甲醇催化转化制碳氢化合物的反应中,粒径为0.1 μm的分子筛催化稳定性最好;随着粒径的增大,其稳定性逐渐下降,粒径为14 μm的分子筛催化剂寿命明显降低。同时,粒径对甲醇转化产物分布也有较大影响;小粒径分子筛有利于生成轻质烃类(C₁～C₄),而大粒径分子筛对C₅以上烷烃和芳烃的选择性较高。     

特殊形貌类雪花状ZSM-5分子筛的合成、表征及甲醇制烯烃催化性能(英文)

美国Mobil公司于1972年首先开发的ZSM-5分子筛是一种高硅三维交叉孔道的沸石分子筛,其孔道结构具有良好的择形作用,因此被广泛应用于芳构化、异构化、烷基化和催化裂化等工业催化过程.ZSM-5分子筛的催化性能与其晶粒尺寸、酸性及形貌等密切相关.改变合成方法和制备参数可以合成出不同形貌的ZSM-5分子筛,但目前关于ZSM-5分子筛形貌对其物理化学性质和催化性能的影响报道较少.本文通过改变模板剂类型,采用水热合成法,制备出了类雪花状、椭圆柱状和夹心糖状三种不同形貌的ZSM-5分子筛.通过X射线荧光光谱(XRF)、N_2物理吸脱附(BET)、扫描电镜(SEM)、X射线衍射(XRD)、固体核磁共振(MAS NMR)、NH_3程序升温脱附(NH_3-TPD)及吸附吡啶的红外光谱(Py-IR)等手段对不同形貌分子筛的物理化学性质、形貌、晶体骨架结构和酸性进行了表征.采用浸渍法制备了Ca/HZSM-5催化剂,以甲醇制烯烃(MTO)为探针反应、着重研究了ZSM-5分子筛形貌和晶体结构特性对其酸性和催化性能的影响.合成的三种不同形貌的ZSM-5分子筛具有相近的SiO_2/Al_2O_3比和比表面积.XRD结果表明,通过改变模板剂类型,可制得结晶度较好的ZSM-5分子筛,其中类雪花状分子筛的(101)晶面比例明显多于其它两种分子筛,而椭圆柱状分子筛则暴露更多的(020)晶面.~(27)Al MAS NMR结果表明,绝大部分Al都以四配位形式存在于三种分子筛骨架中,而类雪花状分子筛的峰强度较低,这是由于Al的配位环境不同(偶极作用弱),说明在类雪花状分子筛的交叉晶面中存在大量扭曲、错位和不对称结构;与其它两种分子筛相比,类雪花状分子筛的~(29)Si MAS NMR谱峰宽化、进一步证明该分子筛骨架结构中存在扭曲、错位和不对称性.NH_3-TPD结果表明,类雪花状HZSM-5分子筛的酸量明显高于其它两种分子筛,在SiO_2/Al_2O_3比相近的情况下、类雪花状HZSM-5分子筛晶体骨架结构的错位、扭曲和不对称性造成了该分子筛中酸量增加;但Py-IR结果表明,类雪花状HZSM-5分子筛的酸量低于其它两种分子筛,这与NH_3-TPD结果有差异,主要是由于类雪花状分子筛几何空间结构和晶界处的扭曲、错位对孔道结构的影响,不利于比NH_3分子大的吡啶分子的扩散,进而影响了吡啶分子在酸性位上的吸附.三种不同形貌的ZSM-5分子筛经Ca改性后比表面积和微孔比表面积均明显下降,其中类雪花状和椭圆柱状催化剂的微孔比表面积下降幅度较大,外比表面积下降幅度较小.这是因为各分子筛的晶体结构和晶面的取向差异,导致Ca离子在分子筛上的扩散行为不同.同时,经Ca改性后,三个催化剂的总酸量均有下降,尤其是类雪花状分子筛酸量下降较为明显,表明其中Ca离子更容易扩散到分子筛孔道内,与更多的酸性位作用,而夹心糖状分子筛表面具有更多的Z字形孔道,不利于Ca离子扩散到分子筛孔道内,因而酸量下降较少.Py-IR结果表明,Ca改性后催化剂的总酸量下降,尤其是B酸明显降低,L酸略有增加,其中类雪花状ZSM-5分子筛催化剂的B酸量最低.甲醇制烯烃反应评价结果表明,随着反应温度升高,三个催化剂的总烯选择性和丙烯选择性均呈先升高后降低的趋势.类雪花状ZSM-5分子筛催化剂在甲醇转化率相近时具有最高的烯烃选择性,在反应温度为460℃时,总烯烃选择性为72%,丙烯选择性达39%.     

Synthesis,characterization and catalytic activity of halo-methyl-bis(salicylaldehyde)ethylenediamine cobalt(II) complexes

The synthesis, characterization and catalytic activity of a series of tetra-halo-dimethyl salen and di-halo-tetramethyl-salen ligands are reported in this paper: α,α′-dimethyl-Salen (dMeSalen) (L¹); 3,3′,5,5′-tetrachloro-α,α′-dimethyl-Salen, (tCldMeSalen) (L²); 3,3′-dibromo-5,5′-dichloro-α,α′-dimethyl-Salen, (dCldBrdMeSalen) (L³); 3,3′,5,5′-tetrabromo-α,α′-dimethyl-Salen, (tBrdMeSalen) (L⁴); 3,3′,5,5′-tetraiodo-α,α′-dimethyl-salen, (tIdMeSalen) (L⁵); 3,3′-dichloro-5,5′,α,α′-tetramethyl-Salen (dCltMeSalen) (L⁶); 3,3′-dibromo-5,5′,α,α′-tetramethyl-Salen (dBrtMeSalen) (L⁷); and 3,3′-diiodo-5,5′,α,α′-tetramethyl-Salen (dItMeSalen) (L⁸) (Salen = bis(salicylaldehyde)ethylenediamine). Upon reaction with Co(II) ions, these ligands form complexes with square planar geometry that have been characterized by elemental analysis, cyclic voltammetry, UV–Vis, IR and EPR spectroscopies. In the presence of pyridine the obtained Co(II) complexes were found able to bind reversibly O₂, which was shown by EPR spectroscopy and cyclic voltammetry. They were also found able to catalyze the oxidation of 2,6-di-tert-butylphenol (DtBuP) (9) with formation of 2,6-di-tert-butyl-1,4-benzoquinone (DtBuQ) (10) and 2,6,2′,6′-tetra-tert-butyl-1,1′-diphenobenzoquinone (TtBuDQ) (11). These properties are first influenced by the coordination of pyridine in axial position of the Co(II) ion that causes an increase of the electronic density on the cobalt ion and as a consequence a decrease in the E_1/2 value and an increase of the reducing power of the Co(II) complex. It is noteworthy that, under those conditions the complexes also show a remarkable quasi-reversible behaviour. Second, complex properties are also influenced by the substituents (methyl and halogen) grafted on the aromatic ring and on the azomethynic groups. The donating methyl substituent on the azomethynic groups causes a decrease in the E_1/2 value, whereas the halogen substituents on the aromatic rings have two effects: a mesomeric donating effect that tends to lower the redox potential of the complex, and a steric effect that tends to decrease the conjugation of the ligand and then to increase the redox potential of the Co(II) complex. In pyridine, the steric effect predominates, which causes both an increase of the redox potential and a decrease of the selectivity of the oxidation of phenol 9. As a result of all these effects, it then appears that the best catalysts to realize the selective oxidation of 2,6-di-tert-butyl-phenol (9) by O₂ are the Co complexes of ligands bearing CH₃ donating substituents, Co(dMeSalen) 1 (2CH₃ substituents), and Co-di-halo-tetra-methyl-salen complexes 6, 7 and 8 (4CH₃ substituents), in the presence of pyridine.     

Synthesis,spectral, and catalytic studies of ruthenium(II) unsymmetrical Schiff-base complexes

Unsymmetrically-substituted ruthenium(II) Schiff-base complexes, [Ru(CO)(B)(L ^x )] [B = PPh₃, AsPh₃ or Py; L ^x = dianion of tetradentate unsymmetrical Schiff-base ligand; x = 4–7, L⁴ = salen-o-hyac, L⁵ = valen-o-hyac, L⁶ = salphen-o-hyac, L⁷ = valen-2-hacn], were prepared and characterized by analytical, IR, electronic, and ¹H NMR spectral studies. The new complexes were tested for their catalytic activity towards the oxidation of benzylalcohol to benzaldehyde.     

焦炉煤气二氧化碳重整制合成气中La0.6Sr0.4NixCo1-xO3钙钛矿催化剂的合成、表征和催化性能研究

采用溶胶凝胶法制备了La0.6Sr0.4NixCo1-xO3钙钛矿催化剂,并测试了该催化剂在焦炉煤气CO2重整反应中的性能.通过X射线衍射、N2吸附脱附、程序升温还原、扫描电镜、透射电镜和热重-微分扫描量热等方法对催化剂进行了表征.结果表明,溶胶凝胶法合成的La0.6Sr0.4NixCo1-xO3催化剂形成了钙钛矿结构的固溶体.着重考察了钙钛矿催化剂焙烧温度和A位Ni的掺杂含量对其催化性能和反应后积碳的影响.结果表明： La0.6Sr0.4NixCo1-xO3钙钛矿催化剂在反应中生成了活性金属Ni, Co颗粒和La2O2CO3,这些组分对催化剂的活性和稳定性起关键性的作用,并且能够抑制积碳的形成;焦炉煤气中的富氢气体具有抑制甲烷裂解反应发生的作用,从而减少催化剂的积碳.     

Catalytic conversion of methanol to olefins over rare earth (La, Y) modified SAPO-34

SAPO-34 modified with lanthanum and yttrium exhibited higher selectivity to light olefins, lower methane formation, and longer lifetime (prolonged by 20%) than the parent SAPO-34 in the process of methanol conversion to olefins. The modified catalytic performance could be ascribed to the incorporation of La³⁺ and Y³⁺ into the framework of SAPO-34.     

Synthesis and spectral characterization of 2'-hydroxy chalconate complexes of ruthenium(II) and their catalytic and biological applications

The reactions of [RuHCl(CO)(B)(EPh(3))(2)] (B=EPh(3) or pyridine; E=P or As) and 2'-hydroxychalcones in 1:2 ratio led to the formation of [Ru(CO)(B)(L)(2)] (B=PPh(3), AsPh(3) or Py; L=2'-hydroxychalcones). The new complexes have been characterized by analytical and spectral (IR, electronic and (1)H NMR) data. They have been assigned an octahedral structure. The new complexes were found to catalyze the oxidation of alcohols to aldehydes using N-methylmorpholine-N-oxide as co-oxidant. All the new complexes were found to be active against bacteria such as E. coli, Salmonella typhi and fungi Aspergillus niger. The activity was compared with standard Streptomycin or Bavistin.     

晶种存在形态对所合成的SAPO-34分子筛性质及其甲醇转化催化性能的影响

采用常规水热合成法、添加粉末晶种和添加含有分子筛前驱体的液相晶种等方法制备了低硅铝比的SAPO-34分子筛。采用XRD、SEM、FT-IR及TPD等表征手段研究了合成方法对晶体结构、形貌、晶粒粒径及酸性的影响。并在固定床上对比了其甲醇转化制烯烃的催化性能差异。结果表明,晶种存在形态对分子筛的结晶度影响不大,但影响了硅在骨架中的分布、晶粒粒径和酸性等。与添加粉末晶种相比,采用含有分子筛前驱体的液相晶种法更有利于减小分子筛晶粒粒径,降低分子筛酸性,提高低碳烯烃选择性。     

酸性分子筛上甲醇催化转化反应机理研究进展

概括了甲醇转化反应机理实验和理论研究方法,介绍了甲醇脱水预平衡阶段的主要机理模型和实验理论依据,重点综述了C-C键形成过程中涉及到的直接机理和"烃池"机理的实验与理论研究进展和存在的问题,探讨了分子筛孔道结构对"烃池"物种结构和反应历程的影响.     

Ruthenium(II) chalconate complexes: Synthesis, characterization, catalytic, and biological studies

A series of new hexa-coordinated ruthenium(II) carbonyl complexes of the type [RuCl(CO)(EPh₃)(B)(L)] (E = P or As; B = PPh₃, AsPh₃ or Py; L = 2′-hydroxychalcones) have been prepared by reacting [RuHCl(CO)(EPh₃)₂(B)] (E = P or As; B = PPh₃, AsPh₃ or Py) with 2′-hydroxychalcones in benzene under reflux. The new complexes have been characterized by analytical and spectral (IR, electronic, ¹H, ³¹P and ¹³C NMR) data. Based on the above data, an octahedral structure has been assigned for all the complexes. The new complexes exhibit catalytic activity for the oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant and also found efficient catalyst in the transfer hydrogenation of ketones. The antifungal properties of the complexes have also been examined and compared with standard Bavistin.     

Study on methanol reforming–inorganic membrane reactors combined with water–gas shift reaction and relationship between membrane performance and methanol conversion

When a methanol reforming–membrane reactor is employed as a hydrogen generator for proton exchange membrane fuel cell (PEMFC), three important aims should be simultaneously achieved in one process, which are methanol conversion improvement, high hydrogen recovery, and high CO removal efficiency. To achieve the aims, we investigated five different configurations of a membrane reactor (a methanol reforming–microporous membrane (MMi) reactor, methanol reforming–mesoporous membrane (MMe) reactor, methanol reforming–mesoporous membrane–water–gas shift (MMeW) reactor, methanol reforming–macroporous membrane (MMa) reactor and methanol reforming–macroporous membrane–water–gas shift (MMaW) reactor). As a result, the MMi reactor was not suitable for a hydrogen carrier of PEMFC due to low hydrogen recovery. The MMe and MMa reactor showed low CO removal efficiency due to low permselectivity of the mesoporous and macroporous membrane. In contrast, the MMeW and MMaW reactor gave simultaneously methanol conversion improvement, high hydrogen recovery, and high CO removal efficiency in one process. The low CO removal efficiency due to low permselectivity of the mesoporous and macroporous membrane was significantly enhanced by the water–gas shift reaction in the permeate side of the MMeW and MMaW reactor. In addition, based on the reaction results in the MMi, MMe and MMa reactor, it was confirmed that methanol conversion in a membrane reactor system is higher as a membrane used in a membrane reactor has higher total permeance difference (∑permeance of products − ∑permeance of reactants).     

Preparation of iron molybdate catalysts for methanol to formaldehyde oxidation based on ammonium molybdoferrate(II) precursor

It was demonstrated that iron molybdate catalysts for methanol oxidation can be prepared using Fe(II) as a precursor instead of Fe(III). This would allow for reduction of acidity of preparation solutions as well as elimination of Fe(III) oxide impurities which are detrimental for the process selectivity. The system containing Fe(II) and Mo(VI) species in aqueous solution was investigated using UV–Vis spectroscopy. It was demonstrated that three types of chemical reactions occur in the Fe(II)–Mo(VI) system: (i) formation of complexes between Fe(II) and molybdate(VI) ions, (ii) inner sphere oxidation of coordinated Fe(II) by Mo(VI) and (iii) decomposition of the Fe–Mo complexes to form scarcely soluble Fe(III) molybdate, Mo(VI) hydrous trioxide and molybdenum blue. Solid molybdoferrate(II) prepared by interaction of Fe(II) and Mo(VI) in solution was characterized by EDXA, TGA, DTA and XRD and a scheme of its thermal evolution proposed. The iron molybdate catalyst prepared from Fe(II) precursor was tested in methanol-to-formaldehyde oxidation in a continuous flow fixed-bed reactor to show similar activity and selectivity to the conventional catalyst prepared with the use of Fe(III).     

Synthesis,characterization, luminescence,antibacterial, and catalytic activities of a palladium(II) complex involving a Schiff base

A new Pd(II) complex of fluorine-containing Schiff base ligand, [Pd₂(L)₂Cl₂] (1) [L?=?N-(4-fluorobenzylidene)-2,6-diethylbenzenamine], has been synthesized using solvothermal method and characterized by elemental analysis, IR-spectroscopy, thermogravimetric analysis, powder X-ray diffraction, UV–vis absorption spectra, and single-crystal X-ray diffraction. Complex 1 is a μ-chloro-bridged dinuclear cyclometallated Pd(II) complex. Thermal analysis indicates that 1 is quite stable to heat. 1 exhibits quadruple emissions in the solid state (λ _max?=?766?nm) and possesses fluorescence lifetimes (τ ₁?=?87.20?ns, τ ₂?=?190.45?ns, and τ ₃?=?1805.10?ns at 616?nm); broad structureless bands at 690–800?nm are tentatively assigned to an excimeric ³IL transition. The Schiff base (L) and its palladium(II) compound (1) have been screened for their antibacterial activity against several bacteria, and the results are compared with the activity of penicillin. Moreover, 1 has been shown to be highly effective in the Heck reaction of 4-bromotoluene with acrylic acid.