关于中职类有机化学教学中甲烷结构教学的探讨

有机化学是中职学校化工类各专业重要的基础理论课,它是研究有机化合物的组成、结构、性质、合成方法、应用以及它们相互转化规律的科学。通过多年的教学实践,感到＂有机化合物的结构＂这一内容,微观抽象,有一定的难度,对教师而言,不好讲,对学生而言,不好学,特别是杂化轨道理论,只有学完大学课程后才能有深刻的理解。那么,对于中职类学生现有的知识水平,作为教者,怎样将杂化轨道理论很直接、很形象地传授给学生呢？

4,4’-二环己基甲烷二氨基甲酸甲酯的制备及结构表征

以4,4’-二环己基甲烷二异氰酸酯(H12MDI)和甲醇为原料,以二月桂酸二丁基锡(DBTDL)为催化剂制备了4,4’-二环己基甲烷二氨基甲酸甲酯(HMDC)。利用熔点测定、红外光谱、元素分析、核磁分析和质谱等手段对得到的两种固体产物A和B进行了表征。结果表明物质A为反-反结构的HMDC;物质B为一混合物,其中不仅含有反-反结构的HMDC,也含有顺-反结构和顺-顺结构HMDC中的至少一种。

基于mcrA克隆文库和PCR-DGGE技术对牛粪为原料的农村户用沼气池产甲烷古菌的多样性研究

基于mcrA克隆文库和PCR-DGGE技术分析,对农村户用沼气池中产甲烷古菌微生物的群落结构进行了分析。经mcrA克隆文库分析,结果表明,沼气池中产甲烷古菌以产甲烷囊菌属(Methanoculleus)和小甲烷粒菌属(Methanocorpusculum parvum)为主,其他类群包括产甲烷菌属(Methanogenium),马氏甲烷八叠球菌属(Methanosarci-na mazei),甲烷盘菌属(Methanoplanus),甲烷杆菌属(Methanobacteriales)和甲烷鬃菌属(Methanosaeta)。经PCR-DGGE分析,沼气池中的古菌主要以产甲烷囊菌属(Methanoculleus)和甲烷粒菌属(Methanocorpusculum)为主,其他类群包括产甲烷菌属(Methanogenium),甲烷盘菌属(Methanoplanus)和甲烷鬃菌属(Methanosaeta)。

妙用水果实施课堂探究教学的探索

科学探究作为新课改的最大亮点之一,应该说无论在理念层面还是实践层面均为广大教师所接受。但在常态教学活动中,教师们设计实验探究的热情并不是很高,部分教师认为探究教学需要花费大量的时间、精力、普通教师难以胜任。作者认为可以利用常见的材料开发出适合课堂的好看又好用的小探究实验。文章就是生活中常见的水果在常态课甲烷及其他相关分子的结构、原电池的工作原理章节教学中应用的一些尝试。

Selective CO Methanation over Ru Catalysts Supported on Nanostructured TiO2 with Different Crystalline Phases and Morphology

Nanostructured titanium dioxides were synthesized via various post-treatments of titanate nanofibers obtained from titanium precursors by hydrothermal reactions. The microstructures of TiO2 and supported Ru/TiO2 catalysts were characterized with X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray analysis, and nitrogen adsorption isotherms. The phase structure, particle size, morphology, and specific surface area were determined. The supported Ru catalysts were applied for the selective methanation of CO in a hydrogen-rich stream. The results indicated that the Ru catalyst supported on rutile and TiO2-B exhibited higher catalytic performance than the counterpart supported on anatase, which suggested the distinct interaction between Ru nanoparticles and TiO2 resulting from different crystalline phases and morphology.

Morphology effect of zirconia support on the catalytic performance of supported Ni catalysts for dry reforming of methane

An immature pinecone shaped hierarchically structured zirconia （ZrO2-ipch） and a cobblestone-like zirconia nanoparticulate （ZrO2-cs）, both with the monoclinic phase （m-phase）, were synthesized by the facile hydrothermal method and used as the support for a Ni catalyst for the dry reforming of methane （DRM） with CO2. ZrO2-ipch is a much better support than ZrO2-cs and the traditional ZrO2 irregular particles made by a simple precipitation method （ZrO2-ip）. The supported Ni catalyst on ZrO2-ipch （Ni/ZrO2-ipch） exhibited outstanding catalytic activity and coke-resistant stability compared to the ones on ZrO2-cs （Ni/ZrO2-cs） and ZrO2-ip （Ni/ZrO2-ip）. Ni/ZrO2-ip exhibited the worst catalytic performance. The origin of the significantly enhanced catalytic performance was revealed by characterization including XRD, N2 adsorption measurement （BET）, TEM, H2-TPR, CO chemisorption, CO2-TPD, XPS and TGA. The superior catalytic activity of Ni/ZrO2-ipch to Ni/ZrO2-cs or Ni/ZrO2-ip was ascribed to a higher Ni dispersion, increased reducibility, enhanced oxygen mo- bility, and more basic sites with a higher strength, which were due to the unique hierarchically structural morphology of the ZrO2-ipch support. Ni/ZrO2-ipch exhibited better stability for the DRM reaction than Ni/ZrO2-ip, which was ascribed to its higher resistance to Ni sintering due to a strengthened metal-support interaction and the confinement effect of the mesopores and coke deposition resistance. The higher coking resistance of Ni/ZrO2-ipch for the DRM reaction in comparison with Ni/ZrOz-ip orignated from the coke-removalabitity of the higher amount of lattice oxygen and more basic sites, confirmed by XPS and CO2-TPD analysis, and the stabilized Ni on the Ni/ZrO2-ipch catalyst by the confinement effect of the mesopores of the hierarchical ZrO2-ipch sup- port. The superior catalytic performance and coking resistance of the Ni/ZrO2-ipch catalyst makes it a promising candidate for synthesis gas production from the DRM reaction.

ZrO_2-modified Ni/LaAl_(11)O_(18) catalyst for CO methanation: Effects of catalyst structure on catalytic performance

We report Ni/LaHA@ZrO2catalysts prepared by a facile modified successive adsorption and reaction method for CO methanation.N2adsorption,X‐ray diffraction,transmission electron microscopy,scanning electron microscopy,thermogravimetric analysis,H2temperature‐programmed reduction,H2temperature‐programmed desorption,X‐ray photoelectron spectroscopy,thermogravimetric analysis,and inductively coupled plasma atomic emission spectrometry were used to characterize the samples.The results indicated that the ZrO2nanoparticles were distributed over the surface of the Ni/LaHA@ZrO2catalyst and even partially covered some Ni particles,resulting in the coating exerting a confinement effect.The excess ZrO2had an adverse effect on the enhancement of CO conversion because of the coverage of the surface Ni particles;however,the Ni/LaHA@ZrO2catalyst displayed much higher CH4selectivity than Ni/LaHA because of the activation of the byproduct CO2molecules by ZrO2species.Therefore,even though20Ni/LaHA@ZrO2‐5exhibited similar CO conversion as20Ni/LaHA,the use of the former resulted in a higher CH4yield than the use of the latter.A107‐h‐lifetime test revealed that the Ni/LaHA@ZrO2catalyst was highly stable with superior anti‐sintering and anti‐coking properties because of its coating structure and the promoter effect of ZrO2.

An alternate aqueous phase synthesis of the Pt3Co/C catalyst towards efficient oxygen reduction reaction

Carbon supported Pt-Co alloys are among the most promising electrocatalysts towards oxygen reduction reaction(ORR)for the application in low temperature fuel cells and beyond,thus their facile and green synthesis is highly demanded.Herein we initially report an alternate aqueous phase one-pot synthesis of such catalysts(containing nominally ca.20 wt.%Pt)based on dimethylamine borane(DMAB)reduction.The as-obtained electrocatalyst(denoted as Pt3Co/C-DMAB)is compared with the ones obtained by NaBH4 and N2H4·H2O reduction(denoted as Pt3Co/C-NaBH4 and Pt3Co/C-N2H4·H2O,respectively)as well as a commercial Pt/C,in terms of the structure and electrocatalytic property.It turns out that Pt3Co/C-DMAB exhibits the highest ORR performance among all the tested samples in an O2-saturated 0.1 mol/L HClO4,with the mass activity(specific activity)ca.4(6)times as large as that for Pt/C.After 10000 cycles of the accelerated degradation test,the half-wave potential for ORR on Pt3Co/C-DMAB decreases only by 4 mV,in contrast to 24 mV for that on Pt/C.Pt3Co/C-NaBH4 or Pt3Co/C-N2H4·H2O shows a specific activity comparable to that for Pt3Co/C-DMAB,but a mass activity similar to that for Pt/C.ICP-AES,TEM,XRD and XPS characterizations indicate that Pt3Co nanoparticles are well-dispersed and alloyed with a mean particle size of ca.3.4±0.4 nm,contributing to the prominent electrocatalytic performance of Pt3Co/C-DMAB.This simple aqueous synthetic route may provide an alternate opportunity for developing efficient practical electrocatalysts for ORR.

Study on Production of Hydrogen from Methane for Proton Exchange Membrane Fuel Cell

The hydrogen production from methane for proton exchange membrane fuel cell (PEMFC) was studied experimentally. The conversion rate of methane under different steam carbon ratios, the effect of the different excess air ratios on the constituents of the gas produced, the permeability of hydrogen under different pressure differences, and the effect of different system pressure on the reaction enthalpy of hydrogen were obtained. The results lay the basis for the production of hydrogen applicable to PEMFC, moreover, provide a new way for the comprehensive utilization of the coal bed methane.

Influence of magma intrusion on gas outburst in a low rank coal mine

The effect of magma intrusion on gas outburst is illustrated by a case study of the exposed magma intru- sion in the 313 mining area, upper coal seam Number 3, in the Qiwu Mine located in Shandong province. Vitrinite reflectance, mercury injection, and maceral statistical analysis are used to characterize the coal. The aspects of coal metamorphism include changes in micro-components as well as in coal structure, the formation of new substances, and changes in gas absorption and storage. The results show that vitrinite reflectance increases within the region influenced by magma intrusion. The metamorphosed region may be divided into a weakly affected belt, a medium affected belt, a strongly affected belt, and a completely affected belt. Compared to the unaffected coal the total pore volume, as well as the amount of big and middle sized holes, increases while the number of transition holes and micro-pores decreases. This diminishes the absorption capacity of the matrix but enlarges the total gas storage space. Vitrinite con- tent initially decreases slightly but then increases rapidly while the inertinite content increases at first but then decreases. Exinite content decreases, then increases, and finally drops to zero. Higher vitrinite, and a lower inertinite, content increase gas absorption ability. This balances reduced adsorption caused by changes to pore structure. Consequently, gas adsorption capacity is not substantially reduced as the coal rank increases. Thermal metamorphism of the coal produces CH4 and other hydrocarbons that increase the total gas content in the coal seam. Asphaltene migrates into the medium and weakly affected regions filling in the pores and fractures there. This plugs the pathway for gas transport. A barrier is formed that hinders gas flow. C02, H2S, N2, and other gases carried in by the magma react to produce C02, which increases in relative concentration and enhances the risk of gas outburst. The two barriers, magma intrusion on one side and the medium and weakly affected belts on the other, as well as the unaf- fected coal seam itself, trap a large amount of gas during the thermal activity. This is the basic reason for gas outburst. These conclusions can enlighten activities related to gas prevention and control in a low rank coal mine affected by ma^ma intrusion.

Interaction of Methane with Single-Walled Carbon Nanotubes: Role of Defects,Curvature and Nanotubes Type

We investigate the interaction of single-walled carbon nanotubes （SWCNTs） and methane molecule from the first principles. Adsorption energies are calculated, and methane affinities for the typical semiconducting and metallic nanotubes are compared. We also discuss role of the structural defects and nanotube curvature on the adsorption capability of the SWCNTs. We could observe larger adsorption energies for the metallic CNTs in comparison with the semiconducting CNTs. The obtained results for the zig zag nanotubes with various diameters reveal that the adsorption energy is higher for nanotubes with larger diameters. For defected tubes the adsorption energies are calculated for various configurations such as methane molecule approaching to the defect sites pentagon, hexagon, and heptagon in the tube surface. The results show that the introduce defects have an important contribution to the adsorption mechanism of the methane on SWNTs.

Prediction of Coal Seam Methane Enriched Areas Using Seismic Data

All coal mine disasters are dynamic geological phenomenon and affected by many factors. However, locating the enriched areas of CSM (coal seam methane) may be the precondition for the successful prediction of such disasters. Traditional methods of investigating CSM enriched areas use limited data and only consider a few important factors. Their success rate is low and cannot meet practical needs. In this paper, an alternative method is proposed. The proce- dure is given as follows: 1) fracture attributes derived from azimuth variations of P-wave data in coal seams and wall rocks can be extracted; 2) AVO attributes, such as the intercept P and gradient G parameters can be extracted from different azimuths from 3D seismic data; 3) seismic cubes can be inverted and the relative attributes of imped- ance cubes can be extracted; 4) using a GIS platform, multi-source information can be obtained and analyzed; these include fracture attributes of coal seams and wall rocks, the thickness of coal seams, the distribution of faults and structures, the depth of coal seams, the inclination and exposure of coal seams and the coal rank. Through this processing procedure, methane enriched areas can be systematically detected.

Effects of Low Concentration Methanol, PVP and PVCap on Structure-I Methane Hydrate Formation

Kinetic mechanisms describing how THIs （thermodynamic hydrate inhibitors） and KHIs （kinetic hydrate inhibitors） work on gas hydrate formation have drawn interests for decades. These mechanisms could be better revealed with more fundamental experimental studies. With experiments performed in an isochoric cell with continuous cooling and stirring, this paper presents observed effects of methanol, PVP （polyvinylpyrrolidone, Mw= 15,000） and PVCap （polyvinylcaprolactam, Mw = 6,000） on both nucleation and growth of structure-I methane hydrate at concentrations 100 to 3,000 ppm （i.e., 0.01 to 0.3 wt%）. The results suggest that methanol had no significant effect on nucleation, while it weakly promoted, spontaneous hydrate growth at an early stage. PVP and PVCap gave reduced average nucleation rate at and prior to hydrate onset, while increased the induction time and the degree of sub-cooling. PVP gave no observable effect on total gas intake and average hydrate growth rate. A decreased total gas intake was observed for all concentrations of PVCap.

Kinetic and Microstructure of SiC Deposited from SiCl_4-CH_4-H_2

Silicon carbide was prepared from SiCl4-CH4-H2 gaseous precursors by isothermal, isobaric chemical vapor deposition (CVD) at atmospheric pressure and temperatures ranging from 900°C to 1100°C. Kinetic studies showed that carbosilane of SiH2Cl2, SiHCl3 and SiCl2 formed from decomposition of SiCl4 and CH4 contributed to the deposition of hexangular facet and granular pebble structured SiC. An average apparent activation energy of 152 kJ·mol-1 was determined. The overall CVD process was controlled not only by the surface reactions but also by complex gas phase reactions. The as-deposited thin film was characterized using scanning electron microscopy, X-ray diffraction and transmission electron microscopy, these analysis showed that the deposited thin film consisted of pure phase of the β-SiC, the growth morphology of β-SiC differs from hexangular facet to granular pebble struc-tures, which varied with substrate length and CVD temperature.

The Supramolecular Arrangement of Methane Halides in Liquid Phase

The IR spectroscopic data indicate the tautomeric transformations of typical aprotonic organic fluids such as methane halides with gross formulas CHX3 （X = Cl, Br）, CH2X2 （X = CI, Br, I） and CCl4 at normal conditions. These transformations lead to the appearance in molecules of activated hydrogen atoms similar in the spectral behaviour to the bounded proton. The classical analysis of IR bands in 5000-600 cm^-1 region, for studied samples and their deuterated derivatives, proves the existence in the presented organic fluids of hydrogen and dihydrogen bonds. This bonding promotes the formation of supramolecular structure in methane halides. The mechanism of unusual binding in liquid phase in terms of common knowledge for the basic chemical properties of the examined compounds is discussed.

CRYSTAL STRUCTURE OF RhCl(dppm)_2·H_2O

C50H46OP4ClRh, RhCl(dppm)2 · H2O, Mr = 922. 2, monoclinic, P21/2, a=10. 532(3), b=22.574(8), c=18. 641(8) A, β=93. 41(3)°, V = 4424 (3) A3, Z = 4, Dc=1. 386 g. cm-3, λ(MoKα) = 0. 71073A , F(000) = 1904. The structure was determined by direct methods and difference Fourier syntheses and refined by full-matrix least-squares to final R = 0. 037 and Rw = 0. 036 for 3432 (F> 6. 0σ(F) ) observed reflections. The structure of the title compound contains RhCl-(dppm)2 and non-coordinated H2O molecules. The rhodium atom is coordinated by one chlorine atom and four phosphorus atoms of two DPPM ligands forming a tetragonal pyramidal configuration.

Study on the effect of methyl bromide and metham sodium fumigation on the soil protozoan community in a greenhouse environment

We examined soil fumigation effects on soil protozoan abundance and community structure in greenhouses and explored the capacity of protozoa to recover after disturbances. A randomized complete block design with five treatments and 4 replicates was set up in Qingzhou, Shandong Province, China. In addition to methyl bromide （MB） and untreated control （CK）, three alternative fumigation treatments were studied, including MB＋VIF （virtually impermeable films）, metham sodium （MS） and MS＋VIF. Tomato cultivars （Lyeopersicum eseulentum Mill）, cv. Maofen-802 were selected as test crops. Results of four fumigations were demonstrated through three-level ten-fold dilution methodology. Abundance of three groups of soil protozoa-flagellates, amoebae, and ciliates was measured from July 2002 to July 2003. Results indicated that two chemical fumigants and their combinations with physical material all significantly repressed soil protozoan abundance. MB was a stronger fumigant than MS, and use of VIF increased their repressive power. The most serious population reduction occurred in amoebae, thus, they also required the longest time to recover. MB and MS also changed the protozoan community structure. MB use decreased the percentage of amoebae but increased percentage of ciliates, while MS incrcased the percentagc of amoebae and decreased the percentage of flagellates in the protozoan community.

SYNTHESIS AND STRUCTURE OF HEXAKIS CDI-μ-(4-CHLORO-BENZYLTHIO ) NICKEL ] TRITETRACHLOROMETHANE SOL-VATE, [Ni(SCH_2C_6H_4Cl-p)_2]_6 · 3CC1_4

C_(86)H_(72)Cl_(20)Ni_6S_(12) , Mr = 2551. 62, monoclinic, space group C2/c, crystal data: a = 30. 322(5), b=14. 168(3), c=26. 453(4) A ,β=101. 00(4)°, V = 11155. 6 A3, Z=4, Dx=1. 519 g/cm3, λ(MoKα) = 0. 71069 A ,μ=17. 370 cm-1, F(000) = 5152, T = 293 K, final R = 0. 078, Rw = 0. 086 for 5610 (I>3σ(I)) reflections. The crystal is composed of discrete [Ni (SCH2C6H4Cl-p)2]6 and CCl4 solvent molecules. The coordination geometries of the Ni atoms are perfect planes sharing S...S edges. The six NiS4 squares are linked with each other forming a hexagonal prism. The p-ClC6H4CH2S- side chains in the molecule are arranged in the axial and equatorial positions alternately with respect to the pseudo-hexagonal axis of the molecule.

Crystal structure and thermal decomposition kinetics of1-(pyridinium-1-yl)propane-(1-methylpiperidinium)bi[bis(trifluoromethanesulfonyl)imide], [PyC_3Pi][NTf_2]_2

The structure of a room temperature asymmetrical dicationic ionic liquid （ADIL）, 1-（pyridinium-l-yl） propane- （1-methylpiperidinium） bi[bis（tfifluoromethanesulfonyl）imide] （[PyC3Pi][NTf2]2）, was studied by the X-ray difo fraction method. Meanwhile, thermal analysis of [PyC3Pi][NTf2]2 was also studied using non-isothermal thermo- gravimetric analysis （TGA）. The title crystal belongs to the triclinic with space group Pi and unit-cell parameters a ： 0.95217 （8） nm, b = 1.05129 （11 ） nm, c = 1.70523 （14） nm, ct = 89,759 （8）°,β = 80.657 （7）°, γ=68.007 （9）°, and F（000） = 792. Thermal stability and thermal decomposition kinetics of the title compound were also investigated using TGA under the atmosphere of highly pure nitrogen. Heating curves at different rates were cor- related with kinetic equations Friedman and ASTM （also called iso-conversion method）. The values of average activation E （kJ·mol^-1 ） and pre-exponential constant lgA are 149.58 kJ. mol- 1 and 8.83, respectively, which were obtained by the two methods. The kinetic model function, activation energy and pre-exponential constant of this reaction using the multivariate non-linear-regression method were f（a） = （1 -a）（1 ＋ 4.1870a）, 151.04 kJ·mol^-1 and 8.81, respectively, which were basically consistent with iso-conversion methods.

The role of volatiles and coal structural variation in coal methane adsorption

We investigated the role of volatiles in the porous structure of coal samples and the corresponding structural deformations that affect the coals＇ methane adsorption capacity. For this study, the volatiles in coal were gradually removed by extraction. Changes in the crystal, textural, and porous structures were identified by means of thermogravimetric analysis, X-ray diffraction, and N2 adsorption/desorption. Changes in the methane adsorption behavior before and after volatile removal were investigated. It was found that changes in methane adsorption could be attributed to volatile-related deformations in the coal＇s porous structure. Microstructural characterizations indicated that the volatiles could be found in two states within the coal, either trapped in the pores, or cross-linked in the network. The former played an important role in constructing the pore spaces and walls within the coal and affected the accessibility of gases. The latter cross-linked state retained the volatiles within the macromolecular coal structural network. This state affected coal-coal interactions, which was a factor that controlled the crystal structure of coal and contributed to the number of porous deformations.