液态水对煤吸附甲烷影响的机理分析

为了研究液态水对煤吸附甲烷影响的机理,进行了不同煤级干燥煤样、平衡水煤样和注水煤样等温吸附实验,基于分子间作用力对液态水影响机理进行分析,并用维里方程拟合等温吸附实验结果来验证.结果表明,煤基质的润湿程度是液态水影响煤吸附甲烷的主要因素.干燥煤样中煤与甲烷分子间作用力远大于甲烷分子间作用力,第二维里系数较低,吸附能力强;平衡水煤样中煤与水分子氢键能高于范德华力,气态水分子竞争吸附,第二维里系数偏高,煤基质吸附能力弱;注水煤样中煤与甲烷分子之间长程作用力和甲烷与水分子之间短程作用力之和较小,与甲烷分子间作用力相当,第二维里系数最高,煤基质吸附能力很低.煤级增高,煤基质表面极性及其润湿程度降低,第二维里系数随之降低.     

液体表面张力与比表面自由能的热力学分析

对液体的表面张力和比表面自由能进行了热力学分析和比较，探讨了液体的表面张力和比表面自由能两个概念的各自内涵和在分子水平上的产生机理，分析了在两者在不同领域的应用和相互之间的联系。研究表明液体的表面张力是从力的角度来分析液体表面现象，是微观分子作用力的宏观表现；比表面自由能是从能量的角度来研究液体表面现象。从微观结构分析可以得出液体的表面张力是液体表面空穴作用的结果，比表面自由能量液体分子作用力作功的结果，两者都与液体分子间的作用力有关。     

基于分子动力学模拟的非离子表面活性剂对煤润湿性影响机制

煤矿深部开采条件下煤尘灾害严重,采用非离子表面活性剂可有效改善煤尘润湿性,抑制煤尘的产生和扩散。为了探究非离子表面活性剂对煤尘表面的润湿过程和润湿机理,采用分子动力学模拟和实验研究相结合的方法,研究了非离子表面活性剂月桂基葡糖苷（APG）与曲拉通X-100（Triton X-100）对煤尘表面润湿性能的影响。基于苯环碳骨架结构建立了三组煤-水界面吸附体系模型,对比分析了表面活性剂在煤表面的吸附平衡构型和分子空间分布,在此基础上计算了煤/表面活性剂/水间相互作用能及能量组成变化,考察了两种非离子表面活性剂与水分子形成氢键的能力。模拟结果表明：达到吸附平衡状态时,非离子表面活性剂分子通过烷基链相互连接,形成聚集状态,在煤-水界面与水-气界面均有分布。Triton X-100通过增强与水分子的相互作用,促进水分子在煤表面的吸附,对煤表面润湿性能影响较大。以河南平顶山矿区丁、戊、己三组煤层煤样为测试对象,开展沉降实验和接触角实验并计算了煤样表面自由能组成,验证了上述模拟结果,利用傅立叶红外光谱（FT-IR）测试测定煤样芳香烃基团特征,进一步验证了Triton X-100与煤分子间的作用机制。室内试验结果表明,Triton X-100对煤表面的润湿效果优于APG,临界胶束浓度时效果最优,且煤尘中的芳香烃含量越高,越利于Triton X-100的吸附。研究成果可为深部开采高效抑尘剂研发提供理论指导和思路借鉴。     

褐煤与水分子相互作用的量子化学计算

高含水量限制着褐煤的大规模利用,研究褐煤持水机理,揭示含氧官能团与水分子间氢键作用的本质,对指导褐煤脱水具有重要的理论意义.通过第一性原理分子动力学(AIMD)模拟褐煤表面水分子的有序结构,采用密度泛函理论(DFT)研究褐煤结构单元和水分子的相互作用.结果表明：界面处水分子分别在0.192 nm和0.322 nm附近形成了第1配位层和第2配位层;褐煤结构单元的负电势极值点主要分布于含氧官能团中氧原子附近,最大达到了-154.20 kJ/mol,正电势的极值点主要分布于含氧官能团和苯环中的氢原子附近,最大为221.08 kJ/mol.水分子处于羧基、羟基、羰基和醚键处的4种二聚体结合能分别为-47.76,-29.44,-40.45和-23.36 kJ/mol,其中静电作用分别占总吸引能的65.92%,67.45%,55.99%和65.19%.分子中原子理论(AIM)拓扑分析估算的总氢键结合能遵循羧基>羟基>醚键>羰基,处于羰基附近的水分子与褐煤结构单元的其他部分相互作用太强,使得水分子与羰基间的作用能最小.     

改性MCM⁃41孔内水分子吸附扩散行为的模拟研究

通过构建多种官能团负载的MCM?41骨架模型，使用GCMC与MD模拟方法计算了水分子在不同亲疏水性质的MCM?41孔内的吸附及扩散性质。结果表明，MCM?41材料的水吸附等温线主要为Ⅱ型；负载到MCM?41孔表面的亲水官能团能够与水分子形成氢键，因此对水分子的相互作用力较疏水官能团高约114.27%；MCM?41孔内水分子的扩散能力与表面官能团的亲水性呈正相关，亲水表面的材料内水分子的扩散系数相较于疏水表面扩散系数高约58.82%；证明了亲水表面的MCM?41材料在含水环境中对孔内水分子的吸附扩散行为具有一定促进作用。     

煤表面对单氧分子的物理吸附机理

煤的氧化自燃是由煤表面对氧的吸附开始．应用量子化学密度泛函理论,研究了煤表面对氧分子的物理吸附机理和吸附过程．结果表明,煤表面与氧分子组成的吸附态中,煤表面苯环碳原子的电子向氧分子中的氧原子转移,导致氧原子的净电荷增加;单氧分子在苯环位置吸附时,其O-O键的伸缩振动频率向低波数位移;单氧分子在侧链位置吸附时,UC14-H16和UO24-UO25红外光谱的振动频率变小,分子之间的作用力减弱了分子的伸缩振动．氧与苯环吸附时的吸附能为30．94kJ／mol,与氨基基团吸附时的吸附能为71．81kJ／mol煤表面侧链吸附放出的热量大于与苯环吸附所放出的热量,侧链吸附对煤的氧化自燃的贡献大于苯环的吸附．     

基于分子动力学模拟的非离子表面活性剂对煤润湿性影响机制

煤矿深部开采条件下煤尘灾害严重,采用非离子表面活性剂可有效改善煤尘润湿性,抑制煤尘的产生和扩散。为了探究非离子表面活性剂对煤尘表面的润湿过程和润湿机理,采用分子动力学模拟和实验研究相结合的方法,研究非离子表面活性剂月桂基葡糖苷（APG）与曲拉通X–100（Triton X–100）对煤尘表面润湿性能的影响;基于苯环碳骨架结构建立3组煤–水界面吸附体系模型,对比分析表面活性剂在煤表面的吸附平衡构型和分子空间分布,计算煤–表面活性剂–水间相互作用能及能量组成变化,考察APG和Triton X–100与水分子形成氢键的能力;以河南平顶山矿区丁、戊、己3组煤层煤样为测试对象,开展沉降和接触角实验并计算煤样表面自由能组成,验证模拟结果,利用傅立叶红外光谱（FT–IR）测试煤样芳香烃基团特征,验证Triton X–100与煤分子间的作用机制。结果表明：达到吸附平衡状态时,非离子表面活性剂分子通过烷基链相互连接,形成聚集状态,在煤–水界面与水–气界面均有分布;Triton X–100通过增强与水分子的相互作用,促进水分子在煤表面的吸附,对煤表面润湿性能影响较大。室内试验结果表明,Triton X–100对煤表面的润湿效果优于APG,质量分数为1.5%时效果最优,且煤尘中的芳香烃含量越高,越利于Triton X–100的吸附。研究成果可为深部开采的高效抑尘剂研发提供理论指导和借鉴。     

煤表面电磁改性红外光谱实验研究

用建立的煤表面电磁改性实验系统对焦作朱村矿无烟煤的电磁表面改性特征进行了研究．结果表明，在不同频率的交变电磁场作用下，煤对甲烷等矿井常见气体的吸附能力明显减弱，主要表现为Langmuir吸附常数b值的降低，是一种典型的表面改性现象．开展了改性前后煤表面的傅立叶红外光谱分析，结果证明，煤表面电磁改性具有时间效应，电磁场不能永久地改变煤的内部基团微观结构。     

吸附过程中甲烷分子和煤表面的作用

采用气体临界参数确定甲烷分子势,并计算出3倍甲烷分子直径内的分子势函数。结合甲烷分子的正三角锥、倒三角锥吸附模型和煤表面的势垒,运用量子力学的理论,考虑极限条件下甲烷分子的经典力学特点,建立了甲烷分子在煤表面吸附势作用下的波动方程。同时考虑到甲烷分子虽然不间断地在煤表面吸附和解吸、单个分子的运动是时间的函数,但甲烷分子在煤表面吸附总量与时间无关,故将平面波动方程中的时间和距离作为两个独立变量,基于这种简化求出甲烷分子平面波动方程的特解。该研究为探索煤表面与甲烷分子间的作用机理及形式奠定了理论基础。     

水分子在铵伊利石表面吸附的密度泛函研究

为实现黏土矿物颗粒界面疏水调控进而提高难沉降煤泥水处理效果,研究了水分子在铵伊利石表面的吸附机理.采用密度泛函理论方法对水分子在铵伊利石有晶格取代的(001)面和不存在晶格取代的(001)面上的吸附进行模拟计算.结果表明:水分子在(001)面吸附的最强活性点位于晶格取代原子Al成键的氧原子处,吸附最稳定的水分子垂直于有NH_4~+的硅氧环,并与NH_4~+和活性原子形成共2个氢键作用,吸附能为-0.67eV,且水分子有将NH_4~+拉离(001)面的趋势;水分子在(001)面的最稳定吸附主要是位于硅氧环空穴上方,水分子与表面氧原子形成3个氢键,吸附能为-0.41eV.2种最稳定吸附均存在微弱的静电吸附.选择合适的阳离子型疏水药剂与NH+4发生交换吸附,覆盖(001)面活性点,破坏水分子的稳定吸附,理论上可实现铵伊利石等黏土类矿物颗粒界面的疏水调控.     

Flotation of quartz using N-(2-aminoethyl)-octadecanamide as collector

1　INTRODUCTIONMuchworkhasbeendoneonthefrothflotationofquartzinRefs .[1 6 ].Bothcationicandanioniccollectorsareemployedinquartzflotation .Ingener al ,thecollectorsarelong chained ,withatleasttencarbonatoms presentinthehydrocarbon portion .Cationiccollectorscommonlyutilizedareamines ,in cluding primaryamines ,secondaryamines ,tertiaryamines,quaternaryammoniumsalts ,sulphoniumsalt,alkylpyridiniumsaltsanddiamine .Foranioniccollec tor ,thecommonlyused ,arecarboxylate ,sulphonate ,alkylsulpha…     

Simulation of the interaction of methane,carbon dioxide and coal

Gas adsorption has an important influence on gas flow in a coal body. Research on the characteristics of coal and gas adsorption is the theoretical basis for studying gas flow in coal. In this paper, the interaction between methane, carbon dioxide and surface molecules of anthracite was simulated using the quantum chemistry method. Adsorption energy and adsorption configurations of different quantities of gas molecules absorbed on the coal surface were calculated. The results show that adsorption between coal and the two kinds of gas molecules is a physical adsorption process and there is an optimal configuration. Gas molecules are more easily adsorbed in the hydroxyl-containing side chain, while it is difficult for them to be adsorbed at the position of the benzene ring. Besides, carbon dioxide molecules are more readily adsorbed on the coal surface than methane molecules. The findings have an important significance in revealing the nature of gas adsorption in coal.     

基于液氮吸附实验的煤层夹矸孔隙结构特征研究

煤层夹矸存在孔隙,具有吸附气体的能力。为研究沁水盆地新景矿煤层夹矸孔隙特征,选择8#煤层夹矸和15#煤层夹矸进行液氮静态吸附法实验研究。根据实验结果对新景煤矿8#煤层夹矸和15#煤层夹矸孔隙结构特征中的比表面积、孔径、孔径占比进行分析。结果表明:新景8#煤层夹矸主要以微孔和小孔为主,微孔和小孔占总孔比的92%以上,新景15#煤层夹矸主要由微孔、小孔和中孔为主,微孔、小孔占67%,中孔占到32%左右。微孔、小孔孔径大小与比表面积和吸附量有较强的相关性。     

Insights into the floatability between spodumene and albite from crystal chemistry standpoint

Spodumene is a silicate mineral rich in lithium. However, the gangue mineral, albite has similar crystal chemical structure and composition to spodumene. In this work, the density functional theory (DFT) calculation was taken to research the floatability from the perspective of crystal chemistry. And contact angle test and reagent adsorption test were used to support the simulation results. In addition, the weighted total density of broken bonds is proposed for the first time to judge the generation probability of cleavage surface. The DFT calculation results display that the Na and Al sites on the albite surface are the adsorption sites of water molecules. While the water molecules only bond with Al atom on the surface of spodumene and each Al site can adsorb only one water molecule. Thus, the wetting effect of water molecules on the albite surface is stronger than that of spodumene. This is consistent with the result of contact angle. In sodium oleate system, the oleic acid anion is adsorbed on the spodumene surface in form of a multicomponent ring while the albite is a single ring. Theoretically, oleic acid anion can be strongly adsorbed on the surface of spodumene and albite under vacuum. The adsorption strength of spodumene is higher than that of albite. However, on hydrated surface, the adsorption strength of oleic acid anion on mineral surface is greatly reduced due to the interaction between water molecules and metal site on mineral surface. Thus, spodumene and albite are hard to float without external activated ions in sodium oleate system.     

Effect of different concentrations of surfactant on the wettability of coal by molecular dynamics simulation

Anionic surfactant sodium dodecyl benzene sulfonate(SDBS) at varying concentrations was selected to investigate the influence on the wettability of Zhaozhuang Coal by molecular dynamics simulation. Six groups of water/surfactant/coal systems with different concentrations were constructed. The influence of surfactant with different concentrations on the wettability of coal was concluded by analyzing various properties from the energetic behaviors to the dynamic characteristics. The results show that the interfacial tension decreases sharply and then rises slowly with the increase of SDBS surfactant concentration,obtaining that surfactants can obviously reduce the interfacial tension. The surfactant molecules could be detected at the water/coal interface through analyzing the system's relative concentration distribution. In addition, the difference in the wettability of surfactants on coal surfaces is caused by the spatial distribution differences of alkyl chains and the benzene ring of the surfactant molecules. And the negative interaction energy between SDBS and the coal surface indicates that adsorption process is spontaneous.Furthermore, it is of great practical significance for improving the dust reduction effect and reducing the disaster of coal dust by exploring the effects of surfactant molecules on the wettability of coal.     

氢分子在Cu (111) 表面吸附与解离的第一性原理研究

采用基于密度泛函理论的第一性原理对氢分子与Cu (111) 表面的相互作用进行了研究。计算结果表明氢分子是否解离取决于氢分子距表面的初始距离和其初始构型。当氢分子垂直于Cu (111) 表面放置时,在距离表面0.37~4.0 ?范围内,氢分子与Cu (111) 表面相互作用后均不会解离,物理吸附在Cu (111) 表面;当氢分子平行于Cu (111) 表面放置时,有的氢分子解离成氢原子后化学吸附于表面六角 (hcp) 或面心 (fcc) 位。氢分子在桥位 (bri) 并沿[211]方向平行靠近Cu (111) 表面时,氢分子解离的临界距离约为1.35 ?,其他情况下在0.65~0.85 ?之间。     

有机氮化物在镍钼硫催化剂的表面吸附

加氢精制过程中,有机含氮化合物的存在会使得贵金属催化剂或酸性催化剂中毒,同时抑制加氢脱硫（HDS）催化剂的活性,因此研究含氮化合物在催化剂表面的吸附行为有助于了解含氮化合物对HDS反应的作用机理.本研究构建一个周期性的镍钼硫（NiMoS）催化剂超晶胞模型,应用密度泛函理论的方法计算了平行吸附和垂直吸附状态下的吡啶、喹啉、咔唑和吲哚在NiMoS催化剂表面的吸附构型和吸附能.结果表明：碱性分子吡啶和喹啉通过Ni-N键吸附在催化剂的表面上,主要表现为垂直吸附;而非碱性分子吲哚通过吡咯环的β-C键吸附在催化剂表面上,咔唑则主要通过苯环吸附在催化剂表面上,两者均以平行吸附为主.比较两类不同吸附构型的吸附能发现,在NiMoS催化剂表面碱性氮化物的吸附能比非碱性氮化物的吸附能高.氮化物在催化剂表面的吸附过程为放热过程.     

Mechanism of micro-wetting of highly hydrophobic coal dust in underground mining and new wetting agent development

The internal mechanism of the high hydrophobicity of the coal samples from the Pingdingshan mining area was studied through industrial, element, and surface functional group analysis. Laboratory testing and molecular dynamics simulations were employed to study the impact of three types of surfactants on the surface adsorption properties and wettability of highly hydrophobic bituminous coal. The results show that the surface of highly hydrophobic bituminous coal is compact, rich in inorganic minerals, and poorly wettable and that coal molecules are dominated by hydrophobic functional groups of aromatic rings and aliphatic structures. The wetting performance of surfactants as the intermediate carrier to connect coal and water molecules is largely determined by the interaction force between surfactants and coal (F_s-c) and the interaction force between surfactants and water (F_s-w), which effectively improve the wettability of modified coal dust via modifying its surface electrical properties and surface energy. A new type of wetting agent with a dust removal rate of 89% has been developed through discovery of a compound wetting agent solution with optimal wetting and settling performance. This paper provides theoretical and technical support for removing highly hydrophobic bituminous coal dust in underground mining.