Oxidative Conversion of Methane/Natural Gas into Higher Hydrocarbons

Oxidative coupling of methane (OCM) to ethylene and ethane is a futuristic process of great practical importance for the effective utilization of methane/natural gas. A brief summary of the work carried out at National Chemical Laboratory (Pune) for the development of catalyst and catalytic process for OCM, particularly addressing the major issues/limitations of the OCM process and efforts made to overcome the problems is presented. This review particularly covers the development of a number of highly active/selective and stable unsupported and supported (using commercial catalyst carriers) catalysts for the OCM process and also the process of improvements/modifications to overcome most of the limitations of OCM.     

Preparation of MoVTe(Sb)Nb mixed oxide catalysts using a slurry method for selective oxidative dehydrogenation of ethane

The preparation of bulk MoVTe(Sb)Nb mixed oxide catalysts using a traditional slurry method, results in highly active catalysts for oxidative dehydrogenation of ethane to ethene. Several major phases including orthorhombic M1, hexagonal M2 or Mo_xM_1−xO_2.8 (M = V or Nb) have been detected in the catalysts from characterization results such as X-ray diffraction (XRD), SEM and EDX analyses. Ethane conversion and yield to ethene increase with increasing content of the M1 phase in the catalysts. The maximum yield of ethene (ca. 87% selectivity and ca. 90% conversion, STY_C2H4 of 176 g  h⁻¹) has been obtained with a MoV_0.31Te_0.2Nb_0.14 mixed oxide catalyst, calcined at 873 K under nitrogen, containing almost pure orthorhombic M1 phase and small amounts of unidentified impurity phases, operating at a relatively low reaction temperature of 673 K. The orthorhombic M1 phase has been shown to be the most active in ethane activation and the most selective for ethene formation. The hexagonal M2 phase is relatively inactive in ethane activation and less selective for ethene formation. The Te-free phases such as Sb₄Mo₁₀O₃₁ and Mo_xM_1−xO_2.8 (M = V or Nb) show the lowest selectivity to ethene.     

镍(II)的两种配位聚合物的合成、晶体结构和性质

分别用水热法和溶液法合成了镍的两种配位聚合物[2{Ni(HO-BDC)(bpe)H₂O}]_n·n(py)·nH₂O (1) (HO-H₂BDC=5-羟基-1,3-苯二甲酸，bpe=1,2-二(4-吡啶)乙烷，py=吡啶)和[Ni(HO-BDC)(bipy)]_n·nH₂O (2) (bipy=2,2’-联吡啶)，并对它们进行了元素分析、红外光谱等表征，并用X-射线单晶衍射测定了配合物的单晶结构。配位聚合物1晶体属三斜晶系,P1空间群,晶体学数据为：a= 1.019 2(2) nm, b=1.145 5(3) nm, c=1.246 0(3) nm, α=68.377(5)°, β=67.275(12)°, γ=71.821(7)°,V=1.222 7(5) nm³, Z=1, M_r=979.26, D_c=1.330 g·cm^-3, F(000)=508, μ=0.835, R₁=0.049 4, wR₂=0.112 1；配位聚合物2晶体属单斜晶系, P2/c空间群,晶体学数据为：a= 0.861 1(2) nm, b=1.106 8(3) nm, c=1.839 4(4) nm, β=104.267(9), V=1.699 0(7) nm³, Z=4, M_r=413.00, D_c=1.615 g·cm^-3, F(000)=848, μ=1.182, R₁=0.063 5, wR₂=0.196 9。配合物1中形成了具有纳米孔的2D结构，而配合物2则是一个1D链状结构，它们分别通过氢键和π-π堆积效应形成3D结构。     

Vibrational Spectroscopic Study of [1,2-bis(4-pyridyl)ethane]metal(II) Tetracyanonickelate(II). 2 m-Xylene Clathrates

Four new Hofmann-type clathrates of the form M(bpa)₂Ni(CN)_4· 2m-xylene (M = Mn , Fe , Co and Ni; bpa = 1,2-bis(4-pyridyl)ethane) have been synthesized and characterized by vibrational spectroscopy. The M(bpa)₂Ni(CN)₄ (M = Fe and Co) host structure is similar to the classical Hofmann-type host framework composed of layers of a two dimensional catena-metal tetra--cyanonickelate(II) network, but in M(bpa)₂Ni(CN)₄ (M = Mn and Ni), the Ni(CN)₄ moiety behaves as a bidentate –[NC-Ni(CN)₂-CN–]– unit in the host framework.     

The Silyl Method for the Synthesis of 1[-2(Phenoxy)ethyl]uracils

A modification of the method for the synthesis of N₍₁₎-substituted derivatives of uracil is proposed using the Gilbert-Johnson reaction, which consists of the alkylation of 5-substituted 2,4-bis(trimethylsiloxy)pyrimidines with 1-bromo-2-(phenoxy)ethanes of low reactivity at 180-185° without solvent. The corresponding 1-[2-(phenoxy)ethyl]uracils, which were obtained in 55-74% yield, contained no impurities of the N₍₁₎, N₍₃₎-disubstituted compounds. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, 1071–1075, July, 2005. cf E. Ya. Lukevics and A. E. Zablotskaya. The Silyl Method for the Synthesis of Nucleosides [in Russian], Zinatne, Riga, 1985, 440 p. (Editor's note).     

In situ CO2 reactivation of FeCrOx/C catalyst in the oxidative dehydrogenation of ethane to ethylene

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Phase Diagrams of the Ternary Gas Hydrate Forming Systems at High Pressures. Part II. Ethane–Methane–Water System

The sections of the phase diagram of a ternary system ethane–methane–water at pressures up to 1000 MPa were studied by means of the differential thermal analysis. The investigation was carried out under the conditions of excessive amount of the gas. It was established that two continuous rows of solid solutions belonging to the II type according to Rosenbom’s classification (with a maximum) exist within the whole pressure range studied: one of them is based on the cubic structure I (CS-I) and another on the cubic structure II (CS-II). With an increase in pressure, the maxima at the decomposition curves of solutions based on CS-II shift towards the hydrates with higher ethane content. This was explained in terms of intrusion of ethane molecules into the small d-cavities of the CS-II which is caused by the pressure imposed.     

Ruthenium Bisphosphine Catalyst on Functionalized Silica： Novel Efficient Catalyst for Carbon Dioxide Hydrogenation to Formic Acid

Catalytic hydrogenation of carbon dioxide to valuable chemicals and fuels has gainedmuch attention recently in view of the abundant availability and the greenhouse effect ofCO2. CO2 hydrogenation to formic acid is an economic reaction, but it is alsotherm…     

Organosilicon backbone containing pyridyl/quinolyl ligands: Synthesis, complexation reactions and single crystal structures of metallamacrocyclic Pd(II) and Cu(II) complexes

Organosilicon backbone containing ligands 1,2-bis(dimethyl(2-pyridyl)silyl)ethane (L¹) and 1,2-bis(dimethyl(3-quinolyl)silyl) ethane (L²) have been synthesized by treating 2-bromopyridine and 3-bromoquinoline with n-butyllithium and reacting the resulting lithiated products with 1,2-bis(chlorodimethylsilyl)ethane. The ligation of L¹ and L² with Pd(II), Ag(I) and Cu(II) has been investigated. The single crystal structures of L², [Pd(L¹)Cl₂] (1), [Cu(L¹)Br₂] (3) and [PdCl₂(L²)]₂ (4) have been solved. All the three complexes are metallamacrocyclic in nature. The last one is 22-membered and the first example which has ligands containing organosilicon backbone. The geometry of Pd as well as Cu is very close to square planar. The Pd–N, Pd–Cl, Cu–N and Cu–Br bond distances (2.010(1)–2.027(3), 2.3063(10)–2.3114(4), 2.004(4)–2.018(5) and 2.4137(10)–2.4172(10) Å) are very close to sum of covalent radii, indicating strong ligation of L¹ and L² with the metal ions.     

乙烷氟氯衍生物常压沸点与结构之间的定量关系

构建了一个新的自相关拓扑指数0 Lk,并研究了乙烷氟氯衍生物的常压沸点Tb 与其基团零价自相关指数0 Lk 之间的定量关系 ,给出了相关方程 ,相关系数 (R =0 .96 33)为良好级 .估算的 36个乙烷氟氯衍生物的常压沸点与实验值相吻合 .还对一些没有常压沸点的乙烷氟氯衍生物进行了预测 ,预测的沸点数据指出CHF2 CHF2是CFC3 可能的代用品