氧化条件下NOx催化的甲烷均相部分氧化

考察了没有固体催化剂时NOx对甲烷气相氧化的促进作用.实验结果表明，即使在强氧化条件下（O2/CH4=5），NOx对甲烷部分氧化制一氧化碳仍然有明显的催化活性.在CH4-O2体系中加入0.005％～0.2％的NO后，反应温度可降低200-300 ℃.在反应产物中还可观察到甲醛和乙烯，通过改变反应条件可以控制它们的相对浓度.     

Experimental and Theoretical Study of the Effect of Moisture on Methane Adsorption and Desorption by Activated Carbon at 273.5 K

Adsorption and desorption of methane by activated carbon (AC) at constant temperature and at various pressures were investigated. The effect of moisture was also studied. A volumetric method was used, up to 40 bar, at a temperature of 273.5 K. Results of a dry AC sample were compared with those obtained from a moist sample and two different ACs with different physical and surface properties were used. As expected, the results showed that the existence of moisture, trapped in the AC pores, could lead to a decrease in the amount of methane adsorbed and a decrease in the amount of methane delivered during desorption. To model the experimental results, a large variety of adsorption isotherms were used. The regressed parameters for the adsorption isotherms were obtained using the experimental data generated in the present study. The accuracy of the results obtained from the different adsorption isotherms was favorably compared.     

SiO2—Al2O3和MgO催化剂上吸附CH3NO2的TPD和IR研究

用TPD和IR方法研究了CH_3NO_2在典型固体酸SiO_2-Al_2O_3和固体碱MgO催化剂上的吸附分解。结果表明,在SiO_2-Al_2O_3表面CH_3NO_2吸附转化为表面甲酰胺物种,后者在高温下分解为CO_2和NH_3。在MgO表面CH_3NO_2吸附形成多种表面化学物种,它们在升温过程中脱附,并通过表面亚硝基甲烷物种分解为NO、C_2H_4、C_2H_6和N_2O.讨论了CH_3NO_2分解过程中表面酸、碱中心的作用。     

The Effect of Nb Loading on Catalytic Properties of Ni/Ce0.75Zr0.25O2 Catalyst for Methane Partial Oxidation

In this study,the effect of Nb loading on the catalytic activity of Ce_(0.75)Zr_(0.25)O_2-supported Ni catalysts was studied for methane partial oxidation.The catalysts were characterized by BET,H_2 chemisorption,XRD,TPR,TEM and tested for methane partial oxidation to syngas in the temperature range of 400-800℃at atmospheric pressure.The results showed that the activity of methane partial oxidation on the catalysts was apparently dependent on Nb loading.It seemed that the addition of Nb lowered the catalytic activity for methane partial oxidation and increased the extent of carbon deposition. This might be due to the strong interaction between NiO and Nb-modified support and reduction of surface oxygen reducibility.     

甲烷直接氧化制甲醇Ⅱ．催化膜反应器（CMR）

采用溶胶－凝胶（Ｓｏｌ－Ｇｅｌ）法制备了微孔结构均匀的“ＳｉＯ＿２／陶瓷”膜和“Ｍｏ－Ｃｏ－·Ｏ／ＳｉＯ＿２／陶瓷”催化功能膜，并用ＸＲＤ、ＳＥＭ和孔径测定等技术进行了表征。在常压、５００～７００℃的条件下，在催化膜反应器（ＣＭＲ）中考察了甲烷氧化制甲醇的反应。在相似的反应条件下（转化率为１．０％），用ＣＭＲ（甲醇选择性１１．２％）可获得较固定床反应器（甲醇选择性４．５％）高得多的甲醇选择性。     

离子缔合物二级散射光谱的分析应用——Ⅱ.汞(Ⅱ)-硫氰酸盐-碱性三芳基甲烷染料体系

研究了[Hg(SCN)_4]~(2-)与结晶紫、孔雀石绿、亮绿或碘绿等碱性三芳基甲烷染料的离子缔合配合物的二级散射(DS)和“反二级散射”(ADS)光谱,以及这类散射光谱的特征、影响因素和反应的适宜条件.确定了散射光强度与溶液中汞(Ⅱ)浓度的关系.提出了用二级散射光谱测定痕量汞的新的高灵敏分析方法,并对反应机理和两种二级散射发生变化的原因作了初步的讨论.     

NiO/SnO2-ZrO2催化剂的制备及甲烷燃烧催化性能的研究

利用正交分析，通过溶胶凝胶－超临界干燥及复合浸渍的方法制备了NiO/SnO2-ZrO2催化剂，进行了活性评价，考察了前驱物、NiO、SnO2含量及制备方法对催化剂活性及稳定性的影响，并采用XRD、TEM对催化剂进行了表征分析，结果表明：NiO/SnO2-ZrO2催化剂具有良好的甲烷燃烧催化性能（t100%=640 ℃），其活性、稳定性与制备参数密切相关，其中NiO含量是影响催化剂活性、稳定性的最主要参数，它对催化剂稳定性和活性的影响规律正相反； SnO2组分的添加使ZrO2单斜相稳定，对催化剂起到了良好的稳定化作用，发现当SnO2含量在6 mol％左右时，催化剂具有较好的稳定性；对于制备方法，在凝胶前加入活性组分有利于催化剂的高活性，而在凝胶后加入活性组分，则有利于催化剂保持较好的稳定性；活性组分前驱物对催化剂性能影响不大，采用Ni(NO3)2作为前驱物较为合适。     

在改进的Ni基催化剂上的甲烷部分氧化制合成气反应

 本文采用高温分解和焙烧硝酸盐的方法合成了一系列Ni基六铝酸盐催化剂BaNiyAl12-yO19-δ (y=0.1、0.3、0.6、0.9和1.0)，并对它们在甲烷部分氧化制合成气反应中的催化性能、催化剂表面积碳及活性组分Ni流失等情况进行了考察。结果表明，该催化剂对甲烷部分氧化制合成气反应具有较好的催化活性，在850 ℃，甲烷转化率和CO选择性分别可达92%和95%。并且催化剂BaNiyAl12-yO19-δ (y=0.3)在100小时的POM反应后，催化剂表面积碳很少，积碳量仅为样品净重的0.8%，特别是100小时反应后，催化剂表面活性组分Ni没有发生流失。这种低积碳量和无活性组分Ni流失与催化剂结构中Ni与相邻原子间的强相互作用有关。     

甲烷在Ni表面及La薄膜上激活解离化学吸附

利用分子束技术改变甲烷的平动能E_k来研究E_k及其法向分量E_n对甲烷在Ni表面及La薄膜上激活解离吸附的影响。对CH_4/Ni及CH_4/La系统, 当甲烷的平动能E_k分别低于58.5 kJ·mol~(-1)及52.3 kJ·mol~(-1)时, 没观察到甲烷的解离吸附。当甲烷的平动能超过此阈值时, 即对CH_4/Ni系统, 当Ek=58.5增至63.8 kJ·mol~(-1)时, 初始沾着几率s_0由0至0.54线性增加; 对CH_4/La系统, 当E_k=52.3增至63.8 kJ·mol~(-1)时, S_0由0至0.49线性增加。这些结果表明, 两个系统的化学吸附是不经过前趋态的直接化学吸附。最后求出CH_4/Ni, CH_4/La系统的表观活化能分别为46.8 kJ·mol~(-1)和38.1 kJ·mol~(-1)。     

Catalytic Combustion of Methane over CO1-xMgxO/Al2O3/FeCrAl Monolithic Catalysts

A series of CoxMgxO/Al2O3/FeCrAl catalysts （x=0-1） were prepared. The structures of the catalysts were characterized using XRD, SEM, and TPR analyses. The catalytic activity of the catalysts for methane combustion was evaluated in a continuous flow microreactor. The results indicated that the active washcoats adhered well on the FeCrAl foils. The phases in the catalysts were Co--xMgxO solid solutions, α-Al2O3, and γ-Al2O3. The surface particle size of the catalysts varied with variations in the molar ratios of Co to Mg. The Co component of the Co1_xMgxO/Al2O3/FeCrAl catalysts played an important role in the catalytic activity for methane combustion. In the Co1-xMgxO/AluO3/FeCrAl series catalyst （x=0.2-0.8）, the catalytic activity in terms of x was in the order of 0.5〉0.2〉0.8 under the experimental conditions. The presence of Mg in these catalysts could promote the thermal stability to a large extent. There were strong interactions between the Co1-xMgxO oxides and the AluO3/FeCrAl supports.