SnO_2/ZnO及ZnO/SnO_2双层膜的气敏性质

采用动态脉冲法研究了ＳｎＯ２／ＺｎＯ及ＺｎＯ／ＳｎＯ２ 双层膜的气敏性质。结果表明：选择合适的膜厚及膜厚比,可获得灵敏度及选择性良好的气敏元件。讨论了一些影响双层膜气敏性质的因素,结合元素的扩散,初步解释了膜厚与灵敏度的关系。     

大气颗粒物及氧化物对CS_2的催化氧化作用

利用原位ＦＴ－ＩＲ,ＸＲＤ,ＢＥＴ,质谱和连续脉冲微反等手段研究了大气颗粒物及 部分氧化物样品上ＣＳ２催化氧化的反应,并对催化剂的晶化状况和比表面等进行了考 察。结果表明,ＣＳ２在氧化物和大气颗粒物样品上发生氧化反应,生成ＣＯＳ及单质Ｓ,部 分样品上生成ＣＯ２;其中以ＣａＯ的催化作用最为明显,Ｆｅ２Ｏ３次之,Ａｌ２Ｏ３的催化能力有 明显减小,ＳｉＯ２最小,大气颗粒物样品对ＣＳ２有明显的催化氧化作用,活性介于Ｆｅ２Ｏ３ 和Ａｌ２Ｏ３之间;收集的大气颗粒物样品成分主要是Ｃａ（ＡＬ２Ｓｉ２Ｏ８）·４Ｈ２Ｏ,即水泥的主要 成分;ＣＳ２在氧化物或大气颗粒物样品上催化生成ＣＯＳ,是由于催化剂表面吸附氧的作 用．报道了大气颗粒物对ＣＳ２具有催化氧化生成ＣＯＳ的能力,揭示了大气中ＣＯＳ来源 的一个重要途径,对ＣＳ２,ＣＯＳ的污染控制研究具有一定的指导意义．     

S2O2-8/ZrO2固体超强酸的研究

以Ｓ２Ｏ８＾２－浸渍无定形Ｚr（ＯＨ）４,制得较ＳＯ４＾２－／ＺrＯ２酸性更强的固体超强酸。用正丁烷异构化反应考察了Ｓ２Ｏ８＾２－／ＺrＯ２的酸性。结果表明,在对 ＺrＯ２有促进作用的非卤素阴离子中,Ｓ２Ｏ８＾２－是最好的促进剂。最佳焙烧条件下Ｓ２Ｏ８＾２－／ＺrＯ２固体超强酸比ＳＯ４＾２－／ＺrＯ２的酸性更强。３５℃下,Ｓ２Ｏ８＾２－／ＺrＯ２上正丁烷异构化反应速率较ＳＯ４＾２－／ＺrＯ２提高了１．２倍     

Na-W-Mn/SiO2催化剂活化甲烷的研究Ⅱ.活性氧物种

制备了不同Ｎａ、Ｗ、Ｍｎ组分的Ｎａ－Ｗ－Ｍｎ／ＳｉＯ２催化剂,并进行了Ｏ２程序升温脱附（Ｏ２－ＴＰＤ）和不同温度下Ｎａ－Ｗ－Ｍｎ／ＳｉＯ２催化剂的ＣＨ４脉冲反应（ＣＨ４－ＰＲ）。研究结果表明,Ｎａ－Ｗ－Ｍｎ／ＳｉＯ２催化剂活化甲烷的活笥氧物种是Ｗ和Ｍｎ提供的、高温下易于流动的表面晶格氧（Ｏ＾２－）。Ｎａ和Ｏ＾２－的活泼性具有重要的促进作用,它可以极化Ｗ、Ｍn的金属一氧键,促进Ｏ＾２－的流动性。Ｎａ     

水蒸汽对PtSn／Al2O3催化剂结构及反应性能的影响

比较研究了Ａｌ２Ｏ３负载的铂及ＰｔＳｎ催化剂在氮气及水蒸汽稀释条件下的丙烷脱氢性能,并利用ＸＰＳ及氢脉冲吸附对催化剂进行了表征。结果表明,水蒸汽可促使Ｐｔ／Ａｌ２Ｏ３催化剂的铂晶粒烧结。与在氮气氛中相比,在水蒸汽存在下反应显著提高了Ｐｔ／Ａｌ２Ｏ３的丙烷转化率,却降低了丙烯的选择性。另一方面,水蒸汽可调变ＰｔＳｎ／Ａｌ２Ｏ３催化剂的结构,破坏了ＰｔＳｎ／Ａｌ２Ｏ３中与锡相互作用的铂簇团结构。从而导     

CCl_2自由基被无机小分子猝灭的速率常数

对ＣＣｌ４／Ａｒ混合气体脉冲直流高压放电产生 ＣＣｌ２自由基,用 ５４１．５２ ｎｍ激光将电子基态 ＣＣｌ２激励到Ａ１Ｂ１（０,４,０）振动能级上．通过检测激发态 ＣＣｌ２时间分辨荧光信号,测得室温下 ＣＣｌ２（Ａ１Ｂ１和 ａ３Ｂ１）被 Ｏ２、Ｎ２、ＮＯ、ＣＯ２、ＣＳ２、Ｈ２Ｏ、ＳＯ２,和ＳＦ６分子猝灭的实验结果．用我们提出的三能级模型分析处理实验数据,获得了ＣＣｌ２（Ａ１Ｂ１）态和 ＣＣｌ２（ａ３Ｂ１）态的碰撞猝灭速率常数 ｋＡ和 ｋａ值．     

SO^2—4／TiO2和SO^2—4／Fe2O3固体超强酸研究

用ＸＲＤ、ＴＧ－ＤＴＧ、ＳＥＭ和化学分析等手段研究了浸渍Ｈ２ＳＯ４的无定形ＴｉＯ２和Ｆｅ２Ｏ３在焙烧过程中的晶化、相变、失水及失硫情况，总结出ＳＯ＾２－４／ＭｘＯｙ型固体超强酸具有与ＳＯ＾２－４／ＺｒＯ２体系相同的形成规律。用ＩＲ光谱和常温正戊烷异构化反应对ＳＯ＾２－４／ＴｉＯ２／Ｆｅ２Ｏ３的超强酸性进行了表征，表明它们与ＳＯ＾２－４／ＺｒＯ２体系具有相似的表面酸位结构，无水状态主要为Ｌ酸位，吸水     

甲烷与二氧化碳在Na_2WO_4-Mn/SiO_2催化剂上反应制C_2烃及其反应机理的研究

考察了Ｎａ２ＷＯ４－Ｍｎ／ＳｉＯ２催化剂上甲烷与二氧化碳反应制Ｃ２烃及其反应机理，８２０℃时，Ｃ２烃选择性可达９４．５％．随着温度的继续升高，虽然甲烷的转化增加，但Ｃ２烃选择性逐渐降低．Ｏ２－ＴＰＤ、ＣＨ４及脉冲实验表明，８００℃脱附的表面晶格氧为活性氧物种，在催化甲烷活化的同时，ＣＯ２可在该催化剂上活化分解为活性氧物种（ＣＯ２→ＣＯ＋Ｏ＊）．     

SO2-4/ZrO2-Al2O3及载Pt催化剂上正丁烷异构化反应

研究了ＳＯ４＾２－／ＺrＯ２－Ａl２Ｏ３固体超强酸催化剂与制备条件的关系,探讨了催化剂表面结构及晶化程度,并在Ｎ２活化条件下用脉冲色谱法考察了催化剂催化正丁烷异构化反庆活性。结果表明,添加Ａ１可提高催化剂的催化剂的催化活性,降低反应温度,载铂对提高催化剂的活性和稳定性更为有效。     

SiO2,Al2O3上涂载TiO2,ZrO2,La2O3制备Pd催化剂的研究

采用浸渍法制备了Ｌａ２Ｏ３，ＴｉＯ２，ＺｒＯ２以单层状态分散在ＳｉＯ２，Ａｌ２Ｏ３上的改性载体。用ＸＰＳ求得它们的最大单层分散阈值为：０．２２ｇＬａ２Ｏ３／１００ｍ＾２ＳｉＯ２，０．２７ｇＬａ２Ｏ３／１００ｍ＾２Ａｌ２Ｏ３，０．０４ｇＴｉＯ２／１００ｍ＾２ＳｉＯ２，０．０３６ｇ ＴｉＯ２／１００ｍ＾２Ａｌ２Ｏ３，０．０７ｇＺｒＯ２／１００ｍ＾２ＳｉＯ２，０．０８ｇＺｒＯ２／１００ｍ＾２Ａｌ２Ｏ３．     

气体放电对SO2和SO32－氧化的影响

研究气体放电对SO2和亚硫酸盐氧化的影响,采用了直流电源和交直流叠加电源进行气体放电.结果表明,气体放电对于SO2氧化促进作用很少;但对溶液中的SO32－的氧化则有明显促进作用.通过对两个反应过程的机理分析,认为亚硫酸盐溶液氧化快是因为气体放电产生的OH等自由基和液相里的亚硫酸根起作用,引发链反应,促进了溶液中四价硫被空气中的O2氧化为六价硫的过程.而气相中的SO2与OH等自由基作用不能形成链反应,所以影响不明显.实验表明,选择交直流叠加电源进行气体放电比用纯粹直流电源放电效果更好.     

Effects of Water Vapor and Ammonia on SO2 Removal from Flue Gases Using Pulsed Corona Discharge

Plasma Chemistry and Plasma Processing - In the study of SO2 removal using pulsed corona discharge, there exists a serious confusion, that is, which kind of reactions, the thermal chemical...     

Evaluation of Energy Utilization Efficiencies for SO2 and NO Removal by Pulsed Corona Discharge Process

Pulsed corona discharge process was applied to the removal of sulfur dioxide and nitrogen oxides from simulated flue gas. The energy transfer efficiency of the pulse generation circuit and the energy utilization efficiencies for SO ₂ and NO removal are evaluated and discussed. When the pulse-forming capacitance was five times larger than the geometric capacitance of the reactor, the energy utilization efficiency was maximized, and the energy requirements for NO and SO ₂ removal could be lowered. With regard to radical utilization efficiency, producing small amounts of radicals frequently was found to be more advantageous than producing large amounts of radicals less frequently. Removal efficiency of SO ₂ increased with the applied peak voltage, but the energy utilization efficiency was nearly independent of the peak voltage when the peak field intensity was high enough to induce corona discharge (above 10 kV cm ^–1 in this system).     

气体放电对SO_2和SO_3~(2-)氧化的影响

研究气体放电对SO2和亚硫酸盐氧化的影响,采用了直流电源和交直流叠加电源进行气体放电.结果表明,气体放电对于SO2氧化促进作用很少;但对溶液中的SO2-3的氧化则有明显促进作用.通过对两个反应过程的机理分析,认为亚硫酸盐溶液氧化快是因为气体放电产生的OH等自由基和液相里的亚硫酸根起作用,引发链反应,促进了溶液中四价硫被空气中的O2氧化为六价硫的过程.而气相中的SO2与OH等自由基作用不能形成链反应,所以影响不明显.实验表明,选择交直流叠加电源进行气体放电比用纯粹直流电源放电效果更好.     

丙烯和氧等离子体直接气相合成环氧丙烷

在室温和大气压下,在针板式反应器中,通过脉冲电晕放电等离子体对分子氧和丙烯直接合成环氧丙烷的活化作用,考察了放电电极间距、电晕放电脉冲电压以及电晕放电重复频率参数对丙烯转化率、环氧丙烷产率和其选择性的影响,反应物及各产物通过在线色谱法进行分析.实验结果表明,在室温和大气压下,用脉冲电晕等离子体法可转化丙烯和氧气直接生成环氧丙烷,适当调节上述各参数可提高环氧丙烷的收率.当反应气总流速为200mL/min,极间距为4mm,脉冲放电电压为18kV,放电频率为120Hz时,环氧丙烷的收率、丙烯的转化率及环氧丙烷的选择性分别为5.15%,19.15%和26.89%.     

等离子体-催化剂耦合作用下CO2的甲烷化研究

常温常压下,利用脉冲电晕等离子体与Ni/γ-Al₂O₃催化剂协同作用CO₂加氢转化生成甲烷,考察了催化剂担载量、放电参数、工艺参数等对反应的影响,并探讨了其反应机理.结果表明,在等离子体与催化剂协同作用下,CO₂加氢生成CH₄,CO₂转化率在催化剂一定担载量范围内随担载量的增加而增加;脉冲电压峰值、重复频率、进气方式、空速等对反应有重要影响;相同条件下,等离子体-催化法优于化学催化法.     

Reversible physical absorption of SO2 by ionic liquids

Ionic liquids can reversibly absorb large amounts of molecular SO(2) gas under ambient conditions with the gas captured in a restricted configuration, possibly allowing SO(2) to probe the internal cavity structures in ionic liquids besides being useful for SO(2) removal in pollution control.     

Adsorption and reaction of CO2 and SO2 at a water surface

The orientation and hydrogen bonding of water molecules in the vapor/water interfacial region in the presence of SO2 and CO2 gas are examined using vibrational sum-frequency spectroscopy (VSFS) to gain insight into the adsorption and reactions of these gases in atmospheric aerosols. The results show that an SO2 surface complex forms when the water surface is exposed to an atmosphere of SO2 gas. Reaction of SO2 with interfacial water leads to other spectral changes that are examined by studying the VSF spectra and surface tension isotherms of several salts added to the aqueous phase, specifically NaHSO3, NaHCO3, Na2SO3, Na2CO3, Na2SO4, and NaHSO4. The results are compared with similar studies of CO2 adsorption and reaction at the surface. A weakly bound surface complex is not observed with CO2.     

SO2和NO在Na-γ-Al2O3上吸附行为的研究

利用吸附曲线和漫反射红外光谱（DRIFTS）研究了150 ℃SO2和NO在Na-γ-Al2O3上的吸附行为。吸附实验在固定床反应器内进行，原料气体积组成为NO (0.1％)、 SO2 (0.51％)、O2 (4.5％)、Ar平衡。研究表明，150 ℃不论气相中是否有氧，Na-γ-Al2O3均能单独吸附SO2或NO，Na-γ-Al2O3单独吸附SO2时，观察不到有SO42-生成，Na-γ- Al2O3单独吸附NO时，NO吸附量较少，有微量NO2（或表面硝酸盐）生成；Na-γ- Al2O3均能同时吸附SO2和NO，SO2和NO在Na-γ- Al2O3上吸附时相互作用，NO促进SO2氧化生成SO42-，SO2吸附量增加，SO2促进NO氧化转化，SO2也促使NO2脱附。气相氧促进了SO2和NO在Na-γ- Al2O3上的吸附以及SO2和NO的相互作用。     

Distillation and detection of SO2 using a microfluidic chip

A miniaturized distillation system is presented for separating sulfurous acid (H(2)SO(3)) into sulfur dioxide (SO(2)) and water (H(2)O). The major components of the proposed system include a microfluidic distillation chip, a power control module, and a carrier gas pressure control module. The microfluidic chip is patterned using a commercial CO(2) laser and comprises a serpentine channel, a heating zone, a buffer zone, a cooling zone, and a collection tank. In the proposed device, the H(2)SO(3) solution is injected into the microfluidic chip and is separated into SO(2) and H(2)O via an appropriate control of the distillation time and temperature. The gaseous SO(2) is then transported into the collection chamber by the carrier gas and is mixed with DI water. Finally, the SO(2) concentration is deduced from the absorbance measurements obtained using a spectrophotometer. The experimental results show that a correlation coefficient of R(2) = 0.9981 and a distillation efficiency as high as 94.6% are obtained for H(2)SO(3) solutions with SO(2) concentrations in the range of 100-500 ppm. The SO(2) concentrations of two commercial red wines are successfully detected using the developed device. Overall, the results presented in this study show that the proposed system provides a compact and reliable tool for SO(2) concentration measurement purposes.