ZrO2—SiO2负载Cu—Ni催化剂的CO2加氢反应性能

采用表面反应改性法,制备了ZrO2-SiO2（ZrSiO)表面复合物载体,用等体积浸渍法制备了ZrSiO担载的Cu-Ni双金属催化剂,借助BET、TPR、IR和微反等技术,研究了ZrSiO及其负载的Ni、Cu双金属催化剂的表面构造,化学吸附及催化CO2加氢的反应性能,结果表明,ZrSiO表面主要是价联型结构,ZrO2引入SiO2表面,可以有效地促进CuO和NiO的还原,在ZrSiO负载的Cu-Ni催化剂表面的Cu或Ni位,CO2发生化学 吸附形成线、剪式、卧式吸附态,在该催化剂上CO2的加氢反应产物主要是CH3OH3、CH4、CO和H2O生成CH3OH的选择性与催化剂组成及反应条件密切相关,在适当的条件,CH3OH的选择性大于90％。     

CO2/H2在不同形态ZrO2上的吸附行为

利用傅立叶变换红外光谱技术(FT-IR)考察了CO2和CO2＋H2在不同形态氧化锆上的吸附和转化行为，结果表明,氧化锆的形态影响CO2的吸附形式和表面物种的生成.无定型氧化锆上主要生成碳酸氢盐和离子碳酸盐，单斜氧化锆上还出现了双齿碳酸盐，而在四方氧化锆上出现最强的线式吸附CO2，并生成聚碳酸盐.在氢气存在的条件下，单斜氧化锆上生成甲烷而在四方氧化锆上则生成甲酸盐.     

CH2(X 3B1)自由基与O2的反应

用时间分辨富里叶红外发射谱仪（ＴＲ－ＦＴＩＲＳ）研究了ＣＨ２（Ｘ＾３Ｂ１）自由基与Ｏ２反应的通道及产物的振动动态布居，基电子态自由基ＣＨ２（Ｘ＾３Ｂ１）由３５１ｎｍ紫外激光光解ＣＨ２ＣＯ生成，观测到振动发态反应产物ＣＯ（ｖ≤１０），ＣＯ２（ｖ３≤７）ＯＨ（Ｈ２Ｏ）和Ｈ２ＣＯ的红外发射，证实存在生成Ｈ２ＣＯ的通道，由光谱拟合得到不同时刻ＣＯ（ｖ）和ＣＯ２（ｖ３）的相对振动布居，发现ｖ＝４能级的布居数     

H2-induced CO adsorption and dissociation over Co/Al2O3 catalyst

The activation of adsorbed CO is an important step in CO hydrogenation. The results from TPSR of pre-adsorbed CO with H2 and syngas suggested that the presence of H2 increased the amount of CO adsorption and accelerated CO dissocia-tion. The H2 was adsorbed first, and activated to form H* over metal sites, then reacted with carbonaceous species. The oxygen species for CO2 formation in the presence of hydrogen was mostly OH*, which reacted with adsorbed CO subsequently via CO*+OH* → CO2*+H*; however, the direct CO dissociation was not excluded in CO hydrogenation. The dissociation of C-O bond in the presence of H2 proceeded by a concerted mechanism, which assisted the Boudourd reaction of adsorbed CO onthe surface via CO*+2H* → CH*+OH*. The formation of the surface species (CH) from adsorbed CO proceeded as indicated with the participation of surface hydrogen, was favored in the initial step of the Fischer-Tropsch synthesis.     

制备方法对Cr/Si-2催化剂在CO2氧化乙烷脱氢制乙烯反应中的催化性能的影响

采用直接水热合成法和浸渍法制备了相同Cr含量的Cr/Si-2催化剂,并在常压固定床微反应器上,考察了它们在CO2或者N2气氛下的乙烷脱氢制乙烯反应中的催化性能及稳定性.由于存在逆水煤气反应和Boudouard反应,CO2能显著促进乙烷的脱氢反应.不论是在CO2还是在N2气氛下,直接水热法制备的催化剂均比浸渍法制备的催化剂显示出更好的催化性能.高价态的Cr物种被认为是催化剂具有高活性的关键.在CO2气氛下的乙烷脱氢制乙烯反应中,浸渍法制备的催化剂比水热法制备的催化剂失活更快,催化剂失活速率的差异可能与它们的氧化还原性质有关.然而在N2气氛下的乙烷脱氢制乙烯反应中,这两种方法制备的催化剂失活速率差异不大.     

Electrocarboxylation of benzyl halides through redox catalysis on the preparative scale

The electrocarboxylation of benzyl halides to the corresponding carboxylic acids through homogeneous charge-transfer catalysis was investigated both theoretically and experimentally to determine the influence of the operative parameters on the yield of the process and on the catalyst consumption. Theoretical considerations, based on fast kinetics of redox catalysis, were confirmed by the electrocarboxylation of 1-phenyl-1-chloroethane catalyzed by 1,3-benzenedicarboxylic acid dimethyl ester performed at a carbon cathode under different operative conditions. We obtained high yields of the target carboxylic acid and experienced a low catalyst consumption by operating with optimized [RX]bulk/[CO2]bulk and [RX]bulk/[catalyst] ratios.     

ZrO2助剂对Ni/SiO2催化剂CO甲烷化催化活性及其吸附性能的影响

采用连续流动微反装置和原位漫反射红外光谱法考察了Ni/SiO₂及添加ZrO₂助剂的Ni/ZrO₂-SiO₂催化剂CO甲烷化催化活性和吸附性能。结果表明,在CO体积分数 1%、空速 5000h^-1、常压的反应条件下,200℃时Ni/ZrO₂-SiO₂催化剂可将CO完全转化。而相同反应条件下Ni/SiO₂催化剂上CO的转化率仅为35%,直至270℃时方可将CO完全转化。由此可见,ZrO₂助剂的添加明显提高了Ni/ZrO₂-SiO₂催化剂的CO甲烷化催化活性。同时,ZrO₂助剂的添加显著提高了Ni/ZrO₂-SiO₂催化剂对CO的吸附能力,H₂存在时可通过在较低温度时形成较多的桥式羰基氢化物来提高Ni/ZrO₂-SiO₂催化剂的CO甲烷化催化活性;CO甲烷化反应条件下,Ni/SiO₂和Ni/ZrO₂-SiO₂催化剂上C-O键的削弱和断裂是经由羰基氢化物 多氢羰基氢化物的途径,而不是经由C-O键的直接断裂途径。     

氧化铈对Pd／Al2O3表面上CO氧化性能的影响

采用ＴＰＤ－ＭＳ及ＴＰＳＲ－ＭＳ技术研究了添加ＣｅＯ２对Ｐｄ／Ａｌ２Ｏ３催化剂上ＣＯ脱附、表面反应及表面氧脱附等性能的影响，考察了不同含氧量的气氛下ＣＯ的氧化活性，结果表明，Ｐｄ－Ｃｅ间的相互作用有利于各自原子上表面氧的吸脱附及ＣＯ的表面反应，并发现ＣＯ２脱附量大小及峰温次序与对ＣＯ的催化氧化活性有一致的对应关系。     

Influence of NO on the Reduction of NO2 with CO over Pt/SiO2 in the Presence of O2

Reduction of NO2 with CO in the presence of NO and excess oxygen, a model mixture for flue gas, over a 0.1% Pt/SiO2 catalyst was studied. The related reaction mechanisms, such as oxidation of CO and NO, were discussed. It was found that there was a narrow temperature window （180-190 ℃） for the reduction of NO2 by CO. When the temperature was lower than the lower limit of the window, the reduction hardly occurred, while when the temperature was higher than the upper limit of the window, the direct oxidation of CO by O2 occurred and thereby NO2 could not be effectively reduced by CO. The presence of NO shifted the window to higher temperatures owing to the inhibition effect of NO on the activation of O2 on Pt, which made it possible to reduce NO2 by CO in flue gas.     

Ionic liquid mediated CO2 activation for DMC synthesis

Promoted catalytic reaction between methanol and CO2 for dimethyl carbonate(DMC) synthesis is conducted over K2CO3/CH3 I catalyst in the presence of ionic liquid under microwave irradiation.The effect of ionic liquids incorporated with microwave irradiation on the yield of DMC is investigated.DMC was found to form at lower temperature in a relative short time,which indicated an enhanced catalytic process by ionic liquid.Among the ionic liquids used,1-butyl-3-methylimidazolium chloride is the most effective promoter.Density functional theory calculations indicate that CO2 bond lengths and angles changed due to the molecular interaction of ionic liquid and CO2,resulting in the activation of CO2 molecules and consequently the acceleration of reaction rate.     

Comparative study on the reaction of methane over a ZnO bed in the absence and presence of CO2

The reaction of zinc oxide with methane in the absence and presence of CO2 were theoretically and experimentally investigated using HSC Chemistry 5.1 software and a fixed bed reactor, respectively. In the absence of CO2 at 1193 K, the reduction of ZnO was accompanied with methane cracking, and metallic zinc, CO, and H2 were the main reaction products. This system could be utilized for the co-production of metallic zinc and synthesis gas, in which ZnO was a donor of oxygen. In the presence of CO2, ZnO plays as a catalyst in the CO2 reforming of methane and produces syngas with the average H2/CO ratio of 0.88 at 1193 K, which was close to the total reaction theoretic value of 1. It was also found that higher temperature favored high CH4 and CO2 conversions. XRD technique was used to characterize the ZnO species. The result showed that there were no differences in the peak profiles of the XRD patterns of the ZnO powder obtained before and after passing the CH4/CO2 mixed gases for 6 h at 1193 K. It is suggested that ZnO functions as a catalyst according to the redox cycle and metallic zinc plays the role of intermediate product in this process.     

Synthesis and spectroscopic studies of some new metal carbonyl derivatives of 1-(2-pyridylazo)-2-naphthol

Interaction of 1-(2-pyridylazo)-2-naphthol (PAN) with [Mo(CO)₆] in air resulted in formation of the tricarbonyl oxo-complex [Mo(O)(CO)₃(PAN)], 1. The dicarbonyl complex [Ru(CO)₂(PAN)], 3, was obtained from the reaction of [Ru₃(CO)₁₂] with PAN. In presence of triphenyl phosphine (PPh₃), the reaction of PAN with either Mo(CO)₆ or Ru₃(CO)₁₂ gave [Mo(CO)₃(PAN)(PPh₃)], 2, and [Ru(CO)₂(PAN)(PPh₃)], 4. All the complexes were characterized by elemental analysis, mass spectrometry, IR, and NMR spectroscopy. The thermal properties of the complexes were also investigated by thermogravimetry.     

Experimental Study of C2Cl3+NO2 Reaction

The free radical reaction of C2Cl3 with NO2 was investigated by step-scan time-resolved FTIR (TR-FTIR) emission spectroscopy. Due to the vibrationally excited products of Cl2CO, NO, and CO, strong IR emission bands were observed with high resolution TR-FTIR spectra. Four reaction channels forming C2Cl3O+NO, CCl3CO+NO, CO+NO+CCl3, and ClCNO+Cl2CO were elucidated, respectively. Spectralˉtting showed that the product CO was highly vibrationally excited with the nascent average vibrational energy of 60.2 kJ/mol. Possible reaction mechanism via intermediates C2Cl3NO2 and C2Cl3ONO was proposed.     

SYNTHESIS AND SPECTRAL STUDIES OF(μ-PHENYLTHIO) (μ-ALKYLTHIO) HEXACARBONYLDIIRON COMPLEXES

Through reductive reaction between PhL1 and μ-S2 Fe (CO/6,tollowed by nucleophilicsubstitution of the intermediate (μ-PhS} (μ-LIS} Fe2 (CO)6 toward RX,nine Fe-S clus-ter complexes of (μ-PhS)(μ-RS)Fe2(CO)6 series have been synthesized.The influence of RX structures on the activities in nucleophilic substitution has been examined and possible steroisomers and isomer ratios of the complexes determined.In addition,the regular variations of isomer's CH3-S and CH2-S which are caused by the anisotropic effects of C-O and orientations of unshared electron pairs on sulfurs,have also been preliminarily discussed.     

Reactions in a Mixture of CH4 and CO2 under the Aciton of Microwave Discharge at Atmospheric Pressure

Reactions between CH4 and CO2 under the action of continuous microwave discharge at atmospheric pressure were studied in a special homemade reactor,The main products were CO and H2,while acetylene and ethylene were also found in the products.Experimental results show that conversions of CH4 and CO2 could be higher than 90% without the presence of any catalyst,Effects of CO2/CH4 molar ratio and total flow rate of the feed gas on the reaction were also investigated.     

Reactions in a Mixture of CH4 and CO2 under the Action of Microwave Discharge at Atmospheric Pressure

Reactions between CH4 and CO2 under the action of continuous microwave discharge atatmospheric pressure were studied in a special homemade reactor. The main products were CO and H2,while acetylene and ethylene were also found in the products. Experimental results show that conversionsof CH4 and CO2 could be higher than 90% without the presence of any catalyst. Effects of CO2/CH4molar ratio and total flow rate of the feed gas on the reaction were also investigated.     

Reduction of NO2 in Flue Gas by CO and Propylene over CuO‐CeO2/SiO2 in the Presence of O2

Catalytic reduction of NO₂ with CO and/or propylene in the presence of NO and excess oxygen, a model mixture for flue gas, was studied over a series of CuO‐CeO₂/SiO₂ catalysts between 120–260 °C. The effect of HCl, an impurity in flue gas, on the activity of the catalysts was evaluated. It was found that a binary oxide catalyst, 2% CuO‐8% CeO₂/SiO₂, was active for the reduction of NO₂ by CO and/or propylene. CO was effective for selective reduction of NO₂ in the presence of NO and O₂ in a temperature window between 160–200 °C while propylene was effective at temperature higher than 200 °C. In the presence of HCl, the activity of the catalyst for reduction of NO₂ with CO was irreversibly deactivated. However, the activity for reduction of NO₂ with propylene was not influenced by HCl.     

La2O3助剂对Au/TiO2催化氧化CO性能的影响

采用溶胶-凝胶法制备了TiO2以及La2O3-TiO2载体, 再用沉积沉淀法制备Au/TiO2和Au/La2O3-TiO2催化剂, 并对催化剂的CO氧化反应活性进行测试. 结果表明, La2O3助剂可以显著提高催化剂催化氧化CO的活性. X射线衍射(XRD)、程序升温脱附(TPD)、N2吸附-脱附(BET)表征结果表明, La2O3助剂不仅提高了催化剂比表面积, 抑制了TiO2晶粒尺寸的长大, 并且增强了TiO2的晶格应变, 在O2气氛吸附过程中主要在TiO2表面形成O-物种. 原位傅立叶变换红外(FT-IR)结果进一步表明, La的掺杂不仅提高了吸附在Au活性位CO的氧化速率, 还使TiO2表面形成第二种活性位, 从而显著提高了催化活性.     

有氧气氛中碱金属改性CuAl复合氧化物催化分解N2O的活性

合成了Cu/Al原子比分别为2.0、3.1、4.1的CuAl类水滑石样品,焙烧得到CuAl复合氧化物。在Cu/Al原子比为3.1的CuAl氧化物表面浸渍碱金属盐溶液,制备改性CuAl复合氧化物,用AES、XRD、FT-IR、BET、H₂-TPR、XPS等技术对催化剂进行了结构表征,考察了CuAl复合氧化物组成、碱金属助剂类型和K的前驱物对改性催化剂在有氧气氛中催化分解N₂O活性的影响。结果表明,Na、K、Cs改性CuAl复合氧化物均提高了催化剂活性,但K助剂的增强效应最显著;钾的不同前驱物改性CuAl复合氧化物的催化活性有显著差异,加入碳酸钾、草酸钾提高了催化剂的活性,而加入醋酸钾、硝酸钾反而降低了催化剂活性。优化出的K改性CuAl复合氧化物催化剂在含氧含水气氛的N₂O分解反应中表现出了较高的活性。     

Reactions in a Mixture of CH_4 and CO_2 under the Action of Microwave Discharge at Atmospheric Pressure

Reactions between CH_4 and CO_2 under the action of continuous microwave discharge at atmospheric pressure were studied in a special homemade reactor. The main products were CO and H2, while acetylene and ethylene were also found in the products. Experimental results show that conversions of CH4 and CO2 could be higher than 90% without the presence of any catalyst. Effects of CO2/CH4 molar ratio and total flow rate of the feed gas on the reaction were also investigated.