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.     

聚乙二醇修饰纳米二氧化锡的制备及气敏特性

以五水四氯化锡为原材料,聚乙二醇为表面包覆剂,用沉淀法制备出二氧化锡纳米粉体.将制得的二氧化锡纳米粉体经过研磨、涂覆、烧结、焊接、老化等步骤即制得旁热式烧结型二氧化锡气敏元件.取少量二氧化锡纳米粉体采用X射线衍射、比表面测试、扫描电镜和透射电镜等测试手段对材料的结构、比表面积和形貌进行了表征;采用静态配气法测试了气敏元件对乙醇、甲醛、丙酮、甲醇等气体的气敏性能.结果表明:制备的二气化锡粉体粒径非常小且均一性比较好,颗粒大小约为5～8nm;比表面积极大,最高达到每克73.29平方米,具有多孔结构,最可几孔径为4.7～6.1nm,多孔结构可形成气体通道有利于气体分子扩散,从而提高气敏性能.通过添加聚乙二醇作为表面包覆剂对二氧化锡进行修饰,提高了二氧化锡材料的气敏性能,研究表明各元件对乙醇、甲醛、丙酮、甲醇等气体都具有很高的灵敏度,具有较大的应用前景.     

气敏半导体薄膜内载流子浓度的研究

气敏半导体薄膜内的载流子浓度与薄膜表面吸附氧密度的关系,可以反映气敏薄膜的敏感性。本文采用刚性能带模型,计算了不同厚度的ZnO薄膜内载流子浓度与表面吸附氧密度的关系,并对结果进行了讨论。计算结果表明,适当选取薄膜的厚度等参数,可以得到高的气敏性。     

氧化铟纳米纤维的制备及其甲醛气敏性能

采用静电纺丝法和随后的热处理过程制备了新颖的氧化铟纳米纤维材料. 利用扫描电子显微镜,透射电子显微镜,X射线衍射等表征手段对该材料形貌和晶体结构进行表征. 结果表明,所得到的纳米纤维材料的直径约为250 nm~300 nm. 这些纳米纤维由氧化铟纳米颗粒组成,而且其颗粒尺寸均一. 将这种纳米纤维材料制备成气敏传感器,研究表明基于该敏感材料的传感器对甲醛具有优异的气敏性能. 氧化铟纳米纤维传感器具有较低的最佳工作温度 200 ℃,并且对低体积浓度为百万分之五的甲醛气体具有2.1的灵敏度响应值. 在探讨甲醛的气敏机理的过程中,认为氧化铟纳米纤维的一维结构、甲醛的高还原性及敏感材料表面吸附氧促使了该材料对甲醛的优异的气敏性能. 此外,通过对传感器的选择性及稳定性测试,传感器对甲醛具有非常好的选择性和稳定性,这为制备高性能的甲醛传感器开拓了一种优异的气敏材料.     

紫外光驱动微纳结构薄膜的气敏特性研究

采用基于有机模板的溶液浸渍-无损转移法制备ZnO微纳多孔有序薄膜,研究了在不同紫外光强度照射下和不同尺寸孔径的ZnO微纳多孔有序薄膜对NO₂气敏性能的影响。结果表明,以500 nm聚苯乙烯（PS）球为模板制备的ZnO微纳多孔薄膜传感器,在0.35 mW/cm3紫外光照射下具有较高的灵敏度、较快的响应和恢复时间。随着紫外光强度的增强和孔径尺寸的增大,ZnO微纳多孔薄膜传感器的灵敏度降低;且在紫外光照射下ZnO微纳有序多孔薄膜对乙醇、甲醛、H₂S、SO₂和CH₄等气体具有很好的选择性。     

Characteristics and Photoeatalytie Effects of Zn/ZnO Nanowhiskers Compared with ZnO Nanoparticles

ZnO nanopowders were prepared by oxidizing Zn vapor in the atmosphere of mixture gas of Ar and O_2 at low pressure.Tetrapod nanowhiskers synthesized at a pressure of 1.6 kPa show pure ZnO feet and Zn phase in the core of the nanopowder.The ellipsoid ZnO nanoparticles were produced at the pressure of 10 kPa.The photodegradation rate of aniline and chemical oxygen demand removal demonstrate that the photocatalytic efficiency of Zn/ZnO nanowhiskers with UV irradiation is higher than that of ZnO nanoparticles. The tetrapod morphology and Zn phase inside nanowhiskers play key a role in photodegradation process.     

NiO功能化修饰ZnO纳米花对二甲苯的选择性检测

制备了一种负载NiO纳米粒子的ZnO纳米花杂化材料,并对其进行了XRD分析、形貌分析及气体传感性能测试。结果表明,表面负载的NiO纳米粒子调节了ZnO纳米花的导电通道;与纯ZnO材料相比,NiO负载量优化后的异质结气敏材料对二甲苯的响应值提高了3.3倍;传感器的选择性得到提高,响应时间缩短。从更广泛的角度提出了通过引入表面异质结构进行功能化修饰高性能半导体金属氧化物气体传感器的方法。     

Growth Mechanism and Characterization of ZnO 3D Nanocrystals by Laser Irradiation & Coaxially Transporting O2

Different three-dimension (3D) nanotetrapods,containing club-like nanocrystals,nanotetrapods and four-foot-like nanocrystals were synthesized from Zinc sheet via CO2 laser irradiation and coaxially transporting O2.Different nanoproducts were fabricated by changing the content of oxygen in the experiment.The morphologies,components,phase structures and optical properties of the products were investigated by a field-emission scanning electron microscopy,an X-ray diffraction,an energy dispersed X-ray spectrometer and a photoluminescence spectroscope.The X-ray diffraction spectra were obtained on a Rigaku D/max 2500PC diffractometer.The experimental results reveal that high quality ZnO nanotetrapods can be fabricated on the special parameters,and growth of ZnO nanotetrapods depends on Vapour-Liquid-Solid(VLS) model,and the content of oxygen in the gas,namely,oxygen partial pressure is one of main factors to control morphologies and optical properties of ZnO nanotetrapods;these advantages above are important for realization of optoelectronic devices.     

粉末溅射ZnO薄膜酒敏元件

针对金属氧化物薄膜气敏元件传统制造工艺中存在的掺杂不稳问题,开发了一种实用化的ZnO薄膜气敏基材料.采用粉末溅射法研制ZnO：1?O2薄膜,利用衬底Al2O3与ZnO晶体均为六方结构的特点,选择适当溅射参数研制出薄膜气敏元件,同时通过悬挂芯片双点焊工艺,使元件更加小型化.长期检测结果表明,此类元件气敏特性和稳定性良好,适合进一步推广应用.     

粉末溅射ZnO薄膜酒敏元件

针对金属氧化物薄膜气敏元件传统制造工艺中存在的掺杂不稳问题，开发了一种实用化的ZnO薄膜气敏基材料.采用粉末溅射法研制ZnO:1%CeO2薄膜，利用衬底Al2O3与ZnO晶体均为六方结构的特点，选择适当溅射参数研制出薄膜气敏元件，同时通过悬挂芯片双点焊工艺，使元件更加小型化.长期检测结果表明，此类元件气敏特性和稳定性良好，适合进一步推广应用.     

Ga掺杂改性ZnO(001)面对CO气敏机理的第一性原理计算

针对目前在理论上还未能解释清楚的ZnO的气敏机理问题,基于第一性原理结合Castep软件包研究了本征ZnO和Ga掺杂改性ZnO(001)面吸附CO分子后的电子结构和能带结构.研究结果表明:掺杂Ga后ZnO的(001)面的总电子态密度分布与掺杂前类似,带隙中未出现其他的电子态,但掺杂后ZnO表面CO吸附前后的电子态密度发生了显著的变化,价带和导带之间的间隙变小,费米能级进入导带.在此基础上,对Ga掺杂改性ZnO(001)面对CO的气敏机理进行了理论解释.     

Growth Mechanism and Characterization of ZnO 3D Nanocrystals by Laser Irradiation ＆ Coaxially Transporting O2

Different three-dimension （3D） nanotetrapods, containing club-like nanocrystals, nanotetrapods and four-foot-like nanocrystals were synthesized from Zinc sheet via CO2 laser irradiation and coaxially transporting O2. Different nanoproducts were fabricated by changing the content of oxygen in the experiment. The morphologies, components, phase structures and optical properties of the products were investigated by a field-emission scanning electron microscopy, an X-ray diffraction, an energy dispersed X-ray spectrometer and a photoluminescence spectroscope. The X-ray diffraction spectra were obtained on a Rigaku D/max 2500PC diffractometer. The experimental results reveal that high quality ZnO nanotetrapods can be fabricated on the special parameters, and growth of ZnO nanotetrapods depends on Vapour-Liquid-Solid（VLS） model, and the content of oxygen in the gas, namely, oxygen partial pressure is one of main factors to control morphologies and optical properties ofZnO nanotetrapods; these advantages above are important for realization of optoelectronic devices.     

溶液处理ZnO纳米火炬阵列薄膜的制备及其气敏性能研究

利用晶种生长和溶液处理相结合的方法在气敏元件表面制备出了ZnO纳米火炬阵列薄膜,该方法在低温下进行,对环境友好且能耗低。对制得的薄膜进行XRD表征,结果表明其主要物相为纤锌矿ZnO;并对该薄膜进行FESEM表征,发现该ZnO纳米火炬呈中空形貌,高5μm,外径2μm,壁厚约200nm,且大小均一、排列有序。这些纳米火炬都是由粒径20nm左右的更细小的ZnO粒子组装而成。此外还讨论了ZnO纳米火炬结构的可能生长机理。最后对这种ZnO纳米火炬阵列薄膜进行了乙醇的气敏性能测试,并与纳米棒和纳米墙等已知形貌的ZnO纳米材料相比较,结果表明纳米火炬结构的ZnO纳米材料具有更优良的气敏性能。     

A facile synthesis of Ag Modified ZnO nanocrystals with enhanced photocatalytic activity

Ag modified ZnO (Ag/ZnO) nanocrystals were prepared by a facile and low temperature wet chemical method. The phase structures, morphologies, and optical properties of the as-prepared samples were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), the Brumauer-Emmett-Teller (BET) surface area, UV-vis diffuse reflectance spectroscopy and photoluminescence (PL) spectra, respectively. The photocatalytic performance of Ag/ZnO with diffent Ag contents was measured with the degradation of methyl orange (MO) at room temperature under UV light irradiation. The experimental results indicated that the well-crystalline ZnO nanopaticles with a size of ca. 4.5 nm exhibited a high photocatalytic activity for the degradation of MO with the apparent rate constant (k) of 1.57 ×10-2 min-1, and the photocatalytic activities of ZnO were further enhanced by modification with silver. When the Ag loading was 3mol%, Ag/ZnO showed the highest photocatalytic acitivity with a k value of 5.452×10-2 min-1, which is 3.5 and 2.5 time more than that of ZnO and commercial P25, respectively.     

氩气流量对丙纶基氧化锌/铜复合膜结构及抗紫外线性能的影响

在室温条件下先用直流溅射的方式在丙纶非织造布表面沉积铜膜,再用射频磁控溅射法在铜膜表面沉积氧化锌薄膜形成层状膜,借助X射线能谱仪（EDX）、扫描电子显微镜（SEM）、原子力显微镜（AFM）和X射线衍射（XRD）观察薄膜结构,通过改变氩气流量研究其对织物紫外线透过率的影响.实验结果表明,随着氩气流量的增加,纳米薄膜颗粒先增大后缩小,紫外线透过率也先升高后降低,在氩气流量为40 mL/min时,紫外线透过率最低.     

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.     

Interface Characteristics Between Colloidal Gold and Kaolinite Surface by XPS

The distribution of gold colloids in kaolinite and the interaction between gold and kaolinite surface were investigated by transmission electron mieroscotgy （TEM） and X-ray photoelectron spectroscopy （ XPS ）. There is strong interaction between the gold particles and the edge surfaces of kaolinite, in low pH solution, the edge surface of kaolinite is positively charged and electrostutic attrcactive force between colloide gold panicles and the positive edge surface of kaolinite woald facilitate the adsorption of colloidal gold particles onto the suface. TEM observation shows that the aggregate morphology of gold particles was dominated by particle-particle interaction and gold particles were adsorbed on the edge surface of kaolinite crystals , resulting from the electrostatic attractive force between colloidal gold particles and the positice surfaces of kaolinite. XPS data show that in Au4 f electron spectra there are four energy peaks related to gold, 83.8 eV, 85.7 eV, 87.5 eV, and 89.4 eV, respectively, which suggests that in chemical states there are metallic gold and Au bonded to O, similar to the form of Au2O3 , and composite Au2O3 is formed between the edge surface of kaolinite and colloidal gold surface.     

In、Sn共掺杂ZnO纳米线的制备及其气敏性能研究

为了改善纯ZnO纳米线的气敏性能,采用物理蒸发法制备出In、Sn共掺杂的ZnO纳米线,利用XRD、SEM、TEM对产物的形貌、结构进行表征,采用CGS-1TP智能气敏分析系统对其进行酒精气敏性能测试.结果表明,制备出的In、Sn共掺杂ZnO纳米线具有六方纤锌矿结构,平均直径约为80nm,In元素与Sn元素的掺杂量分别为0.12%和1.1%.在最佳工作温度225℃条件下,对气体浓度为400ppm的酒精蒸气的灵敏度S(Ra/Rg)为39.06,响应-恢复时间分别为9s和5s,比同等测试条件下纯ZnO纳米线的灵敏度提高63.9%,响应-恢复时间分别缩短1s和2s.     

Au modified ZnO nanowires for ethanol gas sensing

We demonstrated the application of sensors for ethanol gas detection.The ZnO nanowires based sensors with interdigital electrodes were fabricated,and a platform was constructed to test the properties of the sensors.To acquire better response and shorter response/recovery time,the ZnO nanowires were modified with Au.The ethanol gas sensing performance of the pure sensors and those modified with Au nanoparticles were investigated for comparison,and the optimal test temperature of 350℃ was obtained.We found that the response/recovery time for the modified sensor towards 500 ppm of the ethanol gas was reduced by 1.35 and1.42 times compared with the pure sensors,and the sensitivities towards 500 and 10 ppm of the ethanol gas were also increased by 3.18 and 1.35 times,respectively.These proved the enhancement of the Au nanoparticles in the ZnO nanowires based sensors for ethanol gas sensing.     

Treatment of spent caustic by three kinds of photocatalyticoxidation processes

0　INTRODUCTIONCurrentprocessforethyleneproductionisnotenvi ronmentfriendly ,becausealargeamountofspentcausticisdischargedduringthescrubbingofthecrackinggas ,whichcontainshighconcentrationsulfideandorganiccompounds.Sometechniqueshavebeenappliedtotreatthespentcaustic ,includingchemicaloxidation ,neutral izationandprecipitation[1～ 3] .However ,lowremovaleffi ciencyandsecondpollutionarecommonlyinvolvedinthesetechniques .Althoughwetairoxidationprocesscanefficientlyremoveorganiccompoundsinspe…