Ca and Sr co-doping induced oxygen vacancies in 3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts for boosting low-temperature oxidative coupling of methane

It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(A_(2)B_(2)O_(7)-type)catalysts with disordered defective cubic fluorite phased structure were successfully prepared by a colloidal crystal template method.3DOM structure promotes the accessibility of the gaseous reactants(O2and CH4)to the active sites.The co-doping of Ca and Sr ions in La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts improved the formation of oxygen vacancies,thereby leading to increased density of surface-active oxygen species(O_(2)^(-))for the activation of CH4and the formation of C2products(C2H6and C2H4).3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts exhibit high catalytic activity for OCM at low temperature.3DOM La1.7Sr0.3Ce1.7Ca0.3O7-δcatalyst with the highest density of O_(2)^(-)species exhibited the highest catalytic activity for low-temperature OCM,i.e.,its CH4conversion,selectivity and yield of C2products at 650℃are 32.2%,66.1%and 21.3%,respectively.The mechanism was proposed that the increase in surface oxygen vacancies induced by the co-doping of Ca and Sr ions boosts the key step of C-H bond breaking and C-C bond coupling in catalyzing low-temperature OCM.It is meaningful for the development of the low-temperature and high-efficient catalysts for OCM reaction in practical application.

Long-term and combined effects of N-[2-(nitrooxy)ethyl]-3-pyridinecarboxamide and fumaric acid on methane production,rumen fermentation, and lactation performance in dairy goats

Background:In recent years,nitrooxy compounds have been identified as promising inhibitors of methanogenesis in ruminants.However,when animals receive a nitrooxy compound,a high portion of the spared hydrogen is eructated as gas,which partly offsets the energy savings of CH4mitigation.The objective of the present study was to evaluate the long-term and combined effects of supplementation with N-[2-(nitrooxy)ethyl]-3-pyridinecarboxamide(NPD),a methanogenesis inhibitor,and fumaric acid(FUM),a hydrogen sink,on enteric CH4production,rumen fermentation,bacterial populations,apparent nutrient digestibility,and lactation performance of dairy goats.Results:Twenty-four primiparous dairy goats were used in a randomized complete block design with a 2×2factorial arrangement of treatments:supplementation without or with FUM(32 g/d)or NPD(0.5 g/d).All samples were collected every 3 weeks during a 12-week feeding experiment.Both FUM and NPD supplementation persistently inhibited CH4yield(L/kg DMI,by 18.8%and 18.1%,respectively)without negative influence on DMI or apparent nutrient digestibility.When supplemented in combination,no additive CH4suppression was observed.FUM showed greater responses in increasing the molar proportion of propionate when supplemented with NPD than supplemented alone(by 10.2%vs.4.4%).The rumen microbiota structure in the animals receiving FUM was different from that of the other animals,particularly changed the structure of phylum Firmicutes.Daily milk production and serum total antioxidant capacity were improved by NPD,but the contents of milk fat and protein were decreased,probably due to the bioactivity of absorbed NPD on body metabolism.Conclusions:Supplementing NPD and FUM in combination is a promising way to persistently inhibit CH4emissions with a higher rumen propionate proportion.However,the side effects of this nitrooxy compound on animals and its residues in animal products need further evaluation before it can be used as an animal feed additive.

Methane Oxidation to Synthesis Gas Using Lattice Oxygen of La_(1-x)Sr_xMO_(3-λ)(M =Fe,Mn) Perovskite Oxides Instead of Molecular Oxygen

In this paper, the partial oxidation of methane to synthesis gas using lattice oxygen of La1- SrxMO3-λ (M=Fe, x Mn) perovskite oxides instead of molecular oxygen was investigated. The redox circulation between 11% O2/Ar flow and 11% CH4/He flow at 900℃ shows that methane can be oxidized to CO and H2 with a selectivity of over 90.7% using the lattice oxygen of La1- SrxFeO3-λ (x≤0.2) perovskite oxides in an appropriate reaction condition, while the lost lattice x oxygen can be supplemented by air re-oxidation. It is viable for the lattice oxygen of La1- SrxFeO3-λ (x≤0.2) perovskite x oxides instead of molecular oxygen to react with methane to synthesis gas in the redox mode.

Double perovskite oxides Sr_2Mg_(1-x)Fe_xMoO(6-δ) for catalytic oxidation of methane

The double perovskite oxides Sr2Mg1-xF exMoO6-δ were investigated as catalysts for the methane oxidation.The structural properties of catalysts were characterized in detail by X-ray diffraction,X-ray photoelectron spectroscopy and X-ray absorption spectroscopy.The catalytic property was strongly influenced by the Fe substitution.The relation between catalytic performance and the degree of Fe substitution was examined with regard to the structure and surface characteristics of the mixed oxides.The Fe-containing catalysts exhibited higher activity attributable to the possible（Fe2＋,Mo6＋） and （Fe3＋,Mo5＋）valency pairs,and the highest activity was observed for Sr2Mg0.2Fe0.8MoO6-δ.The enhancement of the catalytic activity may be correlated with the Fe-relating surface lattice oxygen species and was discussed in view of the presence of oxygen vacancies.

Assessing Density Functionals for Describing Methane Dissociative Chemisorption on Pt(110)-(2×1)Surface

In this work,we explore the suitability of several density functionals with the generalized gradient approximation(GGA)and beyond for describing the dissociative chemisorption of methane on the reconstructed Pt(110)-(2×1)surface.The bulk and surface structures of the metal,methane adsorption energy,and dissociation barrier are used to assess the functionals.A van der Waals corrected GGA functional(optPBE-vdW)and a metaGGA functional with van der Waals correction(MS PBEl-rVV10)are selected for ab initio molecular dynamics calculations of the sticking probability.Our results suggest that the use of these two functionals may lead to a better agreement with existing experimental results,thus serving as a good starting point for future development of reliable machine-learned potential energy surfaces for the dissociation of methane on the Pt(110)-(2×1)surface.

Selective Oxidation of Methane to Methanol Using Molecular Oxygen on MoOx/(LaCoO3+Co3O4)Catalysts

Comparatively high CH3OH selectivity (60.0%) and yield (6.7%) were obtained on MoOx/(LaCoO3+Co3O4) catalysts in selective oxidation of methane to methanol using molecular oxygen as oxidant. The interaction between MoOx and La-Co-oxide modified the molecular structure of molybdenum oxide and the ratio of O7O ' on the catalyst surface, which controlled the catalytic performance of MoOx/(LaCoO3+Co3O4) catalysts.

Synthesis of 1-(5-nitro-3-benzopseudothiazolyl)-3-(4-phenylazophenyl)-triazene and Its Color Reaction with Cobalt

A new chromogenic reagent, 1 -（5 - nitro- 3 - benzopsendothiazde）- 3 -（4 - phenylazophenyl） - triazene （NBPTPAPT） has been synthesized and used as a sensitive reagent for the spectrophotometric determination of cobalt. In the presence of Tween - 80, the reagent with Co （ Ⅱ ） forms a yellow complex （1 ： 2） in the buffer solution of Na2B4O7 - NaOH at pH 10.54. The apparent molar absorptivity is 1.220× 10^5 L· mol^- 1· cm^- 1 with the linear range of 0 - 240μg/ L for Co （Ⅱ） by dual-wavelength spectrophotometry. Trace cobalt in vitamin B12 and tea samples has been determined with satisfactory results.

Kinetic Modeling the Formation of Low-mature Gases and Analysis of the Possibility to Be Accumulated

At present, shallow gases have received much attention due to low cost in exploration and production. Low-mature gases, as one significant origin to shallow gas, turns to be an important research topic. The present understanding of low-mature gases is confined within some geological cases, and few laboratory studies have been reported. Therefore, the potential and characters of low- mature gases are not clear up to now. Here, two premature samples （one coal and the other shale） were pyrolyzed in a gold confined system. The gaseous components including hydrocarbon gases and non-hydrocarbon gases were analyzed. Based on kinetic modeling, the formation of low-mature gases was modeled. The results showed that during low mature stage, about 178 mL/gTOC gas was generated from the shale and 100 mL/gTOC from the coal. Two third to three fourth of the generated gases are non-hydrocarbon gases such as H2S and CO2. The total yields of C1-5 for the two samples are almost the same, 30-40 mL/gTOC, but individual gaseous hydrocarbon is different. The shale has much lower C1 but higher C2-5, whereas the coal has higher C1 but lower C2-5. Hydrocarbon gases formed during low-mature stage are very wet. The stable carbon isotope ratios of methane range from -40‰ to -50‰ （PDB）, in good consistence with empiric criterion for low-mature gases summed up by the previous researchers. The generation characters suggest that the low-mature gases could be accumulated to form an economic gas reservoir, but most of them occur only as associated gases.

硝基甲烷连续精制工艺稳态模拟及优化

为进一步提纯硝基甲烷产品,实现硝基甲烷与副反应产物的高效分离。提出了一种优化的高纯度硝基甲烷连续生产工艺,该工艺一步法连续生产即可得到合格硝基甲烷产品,避免了反复蒸发冷却操作引发的安全生产事故,可提高生产的安全性保证。通过探究组分特性及交互作用参数,对比了相平衡数据的准确性,进一步严格模拟计算经灵敏度分析得到较优的理论板数、回流比、进料位置等参数,T-101脱轻塔最优理论板数N_(stage)=48,回流比R=7,N_(feed)=15;T-102脱水塔最优理论板数N_(stage)=27,塔顶采出量D=300 kg/h,N_(feed)=18;T-103脱重塔最优理论板数N_(stage)=20,回流比R=0.5,N_(feed)=13。为工业化生产提供了有效指导和数据支持,可有效提高硝基甲烷这种危险化学品的纯度、产量和收率。

Effect of Substitution of Cobalt for Iron in Sr4Fe6O13-δon the Catalytic Activity for Methane Combustion

A series of mixed oxides Sr4Fe6-xCoxO13-δ （x=0, 1, 2, 3, or 4） were prepared by sol-gel method and used for catalytic combustion of methane. The structural properties of oxides were characterized by XRD, TGA, and XPS. The layered intergrowth perovskite-like oxide Sr4FesCoO13 8 exhibits the highest catalytic activity for methane combustion under the experimental conditions. The enhanced catalytic activity of Sr4FesCoO13-δfor methane combustion could be attributed to the increased amount of oxygen vacancy caused by the partial substitution of cobalt for iron in the Sr4Fe6O13, which was confirmed by TGA and XPS.

邻硝基对甲基苯酚的相转移催化合成

研究了用季钅盐作相转移催化剂催化合成邻硝基对甲基苯酚 ,在 1 8%的硝酸、 1 .0 g催化剂、反应温度 2 0℃～ 2 5℃、反应 4 5min的条件下 ,获得 70 %以上的产率 .此法具有产率高、易操作、反应条件温和。

硝基化合物抑制瘤胃发酵甲烷生成的机理研究进展

在畜牧业生产实践中,反刍动物瘤胃发酵会产生大量甲烷(CH_4),对环境温室效应具有重要影响。此外,瘤胃CH_4的产生会导致日粮能量的浪费,降低饲料转化效率。因此,如何控制瘤胃发酵CH_4生成已成为国内外反刍动物营养研究领域的热点科学与技术问题。以硝基乙烷、硝基乙醇、硝基丙醇等为代表的硝基化合物正在以其高效、持续、低剂量等优势在抑制瘤胃发酵CH_4生成研究方面备受青睐。本文重点围绕硝基化合物抑制瘤胃发酵CH_4生成机理及其作用方面的研究进展进行了综述分析。

H和CH_3NO_2分子中C,N,O原子作用反应机理的研究

采用DFT(B3LYP)方法,在6-311G**,6-311++G**,cc-pvtz基组水平上,优化了H自由基分别进攻CH3NO2上的C,N,O原子反应的各驻点的几何结构,研究了反应体系中各反应沿极小能量途径反应分子几何构型的变化,根据计算得出的各反应的位垒和反应热力学参数指出了反应位垒对反应的影响.

用多声子迁移模型理论研究硝基甲烷的分解机理（英文）

基于多声子迁移模型理论分析了撞击诱导硝基甲烷单分子分解反应可能存在的合理的反应路径.发现:对最低三态和基态的分子选择门模式分别为407 cm-1,436 cm-1和482 cm-1,616 cm-1时,计算得到的相同时间长度上的能量迁移参数分别为5.43×105J/mol*K,5.82×105J/mol*K和8.22×105J/mol*K,6.43×105J/mol*K.而理论计算CH3NO2分子从基态跃迁致最低三态所需能量为2.39×105J/mol,最低三态分子从C-N键断裂分解为硝基和甲基所需活化能为3.69×105J/mol;基态的CH3NO2分子从CN键断裂生成硝基和甲基所需能量为2.24×105J/mol.因此,能量迁移能够提供足够的能量使CH3NO2分子在基态或者在跃迁至最低三态后从C-N键断裂生成硝基和甲基.这个结论与实验报道的结论基本一致.

撞击诱导硝基甲烷分子第一步分解反应的动力学计算

本文基于分子温度与压强的关系,计算在不同压强下基态和最低三态硝基甲烷的分子温度,对应计算其沿着CN键裂解反应的热化学和动力学参数.发现基态的硝基甲烷沿着CN键的分解反应是吸热反应,不具自发性,反应转换温度为1550.2 K,平衡常数在80-1202 K温度范围内很低.最低三态的硝基甲烷沿着CN键的裂解是放热反应,反应的Gibbs自由能在80-2558.5 K范围内为负,有好的自发性,且反应较为彻底.298.15-2558.5 K温度范围内反应活化能随着温度的升高而改变,使反应速率随着温度的升高而急剧增大.对应硝基甲烷爆压15 GPa,其分子温度为4617.6 K,该温度下三态分子分解反应的反应速率为1.088×10~8cm^3·mol^(-1)·s^(-1).推算硝基甲烷沿着CN键分解反应混合物的终态温度,当混合物为硝基、甲基和基态的硝基甲烷分子时,反应的终温为1611.37 K,等效能为1676.47 cm^(-1).当混合物为硝基、甲基、基态和最低三态的硝基甲烷分子时,反应的终温为1184.79 K,等效能为1232.65 cm^(-1).两种情况下终态等效能都足以维持硝基甲烷分子沿C-N键裂解反应的发生.这个能量也足以导致混合物中的NO_2分解为NO和O,这与实验检测的结论相一致.

一溴硝基甲烷的内标分析法

选择正癸烷作为分析一溴硝基甲烷的内标物,使用GC112A型气相色谱仪,在确定的温度、气体流量、进样量、保留时间等气相色谱操作条件下,对四种不同比例的一溴硝基甲烷和正构十碳烷烃进行检验,采用微机归一,求出相对质量校正因子(f)值,进行一溴硝基甲烷含量测定。对此方法的准确度和精确度进行测试,结果表明,本方法测定一溴硝基甲烷偏差≤0.5%,回收率≥98.90%,且有较宽的线性响应。

大气痕量气体与全球温室效应

随着工业生产和人类活动的加强,大气中痕量气体（如二氧化碳、甲烷、氧化亚氮、氟氯烃类等）含量明显增加。这种增加有可能破坏臭氧层、导致全球温室效应。阐述这些气体导致温室效应的机理,总结这些痕量气体近年来在大气中的浓度变化趋势,分析引起这些变化的机理。

Characteristics and control mechanisms of coalbed permeability change in various gas production stages

According to dimensionless analysis of the coalbed methane （CBM） production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM well production process into four stages, i.e., drai- nage stage, unstable gas production stage, stable gas pro- duction stage, and gas production decline stage. By the material balance method, the coal reservoir permeability change in different stages is quantitatively characterized. The characteristics and control mechanisms of change in coalbed permeability （CICP） during different production stages are concluded on five aspects, i.e., permeability trend variation, controlling mechanism, system energy, phase state compositions, and production performance. The study reveals that CICP is characterized by first decline, then recovery, and finally by increase and is controlled directly by effective stress and matrix shrinkage effects. Further, the duration and intensity of the matrix shrinkage effect are inherently controlled by adsorption and desorp- tion features.

Molecular simulation studies of hydrocarbon and carbon dioxide adsorption on coal

Sorption isotherms of hydrocarbon and carbon dioxide （CO2） provide crucial information for designing processes to sequester CO2 and recover natural gas from unmineable coal beds. Methane （CH4）, ethane （C2H6）, and CO2 adsorption isotherms on dry coal and the temperature effect on their maximum sorption capacity have been studied by performing combined Monte Carlo （MC） and molecular dynamics （MD） simulations at temperatures of 308 and 370 K （35 and 97 ~C） and at pressures up to 10 MPa. Simulation results demonstrate that absolute sorption （expressed as a mass basis） divided by bulk gas density has negligible temperature effect on CH4, C2H6, and CO2 sorption on dry coal when pressure is over 6 MPa. CO2 is more closely packed due to stronger interaction with coal and the stronger interaction between CO2 mole- cules compared, respectively, with the interactions between hydrocarbons and coal and between hydrocarbons. The results of this work suggest that the ＂a＂ constant （pro- portional to TcPc） in the Peng-Robinson equation of state is an important factor affecting the sorption behavior of hydrocarbons. CO2 injection pressures of lower than 8 MPa may be desirable for CH4 recovery and CO2 sequestration. This study provides a quantitative under- standing of the effects of temperature on coal sorptioncapacity for CH4, C2H6, and CO2 from a microscopic perspective.

Spectral,Thermal and Structural Studies of Two 3D Coordination Polymers Based on Tetracarboxylic Ligand

Two new coordination polymers,[M6L3（DMA）3（H2O）]（M=Zn for 1,Cu for 2,L=tetrakis[3-（carboxyphenyl）oxamethyl]methane acid,DMA = N,N-dimethylacetamide） have been solvothermally synthesized. Single-crystal X-ray diffraction analysis reveals that compounds 1 and 2 are isostructural and crystallize in the trigonal space group R. The asymmetrical unit contains two metal ions,one L^4- ligand and two coordinated DMA molecules. The metal ions are connected through six aromatic rings into a linear trimetallic zinc building unit. The whole structure is connected through tetrehedral ligand and the trimetallic building units to form a 4,6-connected framework of the toc topology. Compounds 1 and 2 are further studied by IR spectroscopy,thermogravimetric analyses and PXRD. The solid-state UV-Vis and photoluminescent properties of compounds 1 are also investigated.