VOx/AlPO4催化剂合成及其催化苯羟基化反应性能

以异丙醇铝与磷酸为原料，离子液体1-丁基-3-甲基咪唑溴盐([Bmim]Br)与二正丙胺为共模板剂合成了Al PO₄，进而采用水热法将V₂O₅负载于Al PO₄载体制备了VO_x/Al PO₄催化剂。采用XRD、SEM、TEM、Mapping、FTIR、N₂吸附-脱附、XPS对催化剂进行了表征，考察了其在苯羟基化反应中的催化性能。结果表明，钒氧化物负载量为16%(以V₂O₅和Al PO₄的总质量为基准，下同)的催化剂具有最多且分布均匀的V⁴⁺活性中心、契合反应的酸性微环境，在催化剂用量为0.2 g，苯用量4 mL，质量分数30%的H₂O₂用量12.5 mL，乙腈用量15 mL，反应温度70℃，反应时间7 h的条件下，苯转化率为53.4%，苯酚选择性为98.4%。基于催化剂表征分析及性能评估，推测催化反应机理...     

Au/MOF-5催化剂在三组分偶联反应中的催化性能

采用浸渍法制备了Au/MOF-5催化剂,用X射线衍射(XRD)、N₂物理吸附、红外光谱(IR)、热重分析(TG-DTA)、电感耦合等离子体原子发射光谱(ICP-AES)和透射电镜(TEM)对催化剂进行表征,并探索其在醛、炔和胺三组分(A³)偶联反应中的催化性能。实验结果表明:Au/MOF-5对醛、炔和胺三组分偶联反应具有较好的催化活性,而且对产物炔丙基胺的选择性为100%。Au/MOF-5对反应底物具有较宽的适用范围,对于芳香醛和脂肪醛、二级胺和N-烷基取代苯胺、芳香炔和脂肪炔均具有较好的催化活性,而且对于吸电子芳香醛的催化活性大于供电子芳香醛。Au/MOF-5可以循环使用至少3次,催化活性变化不大。     

类水滑石的制备及其焙烧产物催化苯制苯酚

采用共沉淀法制备了类水滑石CuNiAl,450 ℃焙烧后得到复合氧化物催化剂,利用XRD和FT-IR对其结构进行表征。研究了该催化剂体系对苯直接氧化制苯酚反应的催化性能,并考察了反应温度、反应时间、催化剂用量、溶剂用量和n(C₆H₆)∶n(H₂O₂)对收率的影响。结果表明,类水滑石CuNiAl经焙烧后,催化苯直接氧化制苯酚反应的转化率提高,适宜的反应条件为：反应温度65 ℃,反应时间6 h,催化剂用量10 mg,溶剂用量15 mL,n(C₆H₆)∶n(H₂O₂)=3∶1,产物中没有发现副产物,苯转化率达6.5%。     

MOF-199@GO改性PVDF荷电纳滤膜的制备及其性能

采用原位生长法制备了MOF-199@氧化石墨烯（GO）纳米复合材料,并对聚偏氟乙烯（PVDF）支撑膜进行表面改性,以克服PVDF膜表面疏水性。通过界面聚合反应,制备了基于MOF-199@GO改性PVDF的聚酰胺复合荷电纳滤膜。采用XRD、SEM、TEM、AFM和zeta电位等手段表征了MOF-199@GO复合材料及MOF-199@GO改性PVDF聚酰胺复合纳滤膜的结构及微观形貌,并测试了MOF-199@GO改性PVDF聚酰胺复合纳滤膜的脱盐性能。结果表明：通过MOF-199@GO复合材料对PVDF支撑膜的表面改性,有效克服了PVDF支撑膜的疏水性,实现了表面聚酰胺薄层的均匀连续生长,荷电纳滤膜表面荷负电性能显著增强,其中经MOF-199@GO充分改性的复合荷电纳滤膜表现出优异的脱盐性能,对MgSO₄、Na₂SO₄、NaCl和MgCl₂四种盐的截留率分别达到了93.56%、93.04%、87.48%和87.11%。     

三元含铜类水滑石制备及其催化性能

采用共沉淀法制备三元含铜类水滑石CuNiAl-LDHs、CuMgAl-LDHs和CuZnAl-LDHs,利用X射线衍射和傅立叶红外光谱对催化剂结构进行表征,研究该催化剂体系对苯直接氧化制苯酚反应的催化性能。在反应温度65 ℃、反应时间6 h、催化剂用量10 mg、溶剂用量15 mL和n(C₆H₆)∶n(H₂O₂)=3∶1的条件下,CuNiAl-LDHs具有较高的催化活性,苯转化率达4.1%,苯酚选择性100%,无副产物。     

固体超强酸Fe2O3/SO2-4催化合成硝基苯工艺的研究

硝酸铁溶于氨水得到Fe(OH)₃后再用硫酸浸泡，经过滤、焙烧制得固体超强酸催化剂 e₂O₃/SO₂^-4。以固体超强酸Fe₂O₃/SO₂^-4为催化剂、苯和硝酸为原料合成硝基苯。通过正交设计考察了不同工艺条件下苯硝化反应的收率影响因素，最佳反应条件为：催化剂活化温度500 ℃，反应温度75 ℃，n(硝酸)∶n(苯)＝2，m(苯)∶m(催化剂)＝20，反应时间3 h，收率达83.9%。     

Cu/Co掺杂多孔炭活化过硫酸盐降解水中硝基酚研究

以MOF-74为模板制备了Cu/Co双金属掺杂多孔炭催化剂。用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、N₂物理吸附/脱附等对催化剂结构进行了表征。研究并阐释了Cu/Co双金属掺杂多孔炭催化剂活化过一硫酸盐(PMS)氧化降解4-硝基酚性能及机理。结果表明，在投加100 mg·L^-1催化剂、2 g·L^-1 PMS、初始pH为6时，15 min内硝基酚(60 mg·L^-1)去除率达98%以上。降解反应符合伪一级反应动力学模型。催化剂循环反应4次，降解率均高于90%。猝灭实验及电子顺磁共振分析表明自由基(·SO₄^-、·OH、·O₂^-)和非自由基(¹O₂)均参与了降解反应。在反应过程中，Co²⁺/Co³⁺和Cu+/Cu²⁺的氧化还原循环有效活化了PMS并促进活性氧化物种的生成，从而提升了催化剂...     

纳米金/香草醇基介孔碳催化剂在苯甲醇氧化中的应用

以木质素降解产物香草醇替代苯酚，合成中加入金前驱体和稳定剂，在模板剂F127(EO₁₀₆PO₇₀EO₁₀₆)存在下，一步法合成了具有蠕虫状孔道结构的纳米金/香草醇基介孔碳催化剂。催化剂催化氧化苯甲醇性能良好。优化条件为：催化剂用量25 mg，苯甲醇1 mmol，碳酸钾用量2 mmol，水用量5 mL，反应温度100℃，反应时间6 h。优化条件下，苯甲醇转化率为98.4%，苯甲酸选择性为98.0%。催化剂重复使用4次，其催化性能基本保持不变。     

CO/N2/CO2在MOF-74(Ni)上吸附相平衡和选择性

主要研究了MOF-74(Ni)材料对CO/N₂/CO₂的吸附分离性能。应用水热法合成制备MOF-74(Ni),分别采用全自动表面积吸附仪、P-XRD、扫描电子显微镜对材料的孔隙结构和晶体形貌进行了表征,应用静态吸附法测定了CO、N₂和CO₂在MOF-74(Ni)上的吸附等温线,应用DSLF方程模拟了3种气体MOF-74(Ni)上的吸附等温线,依据IAST理论模型计算了MOF-74(Ni)对CO/N₂二元混合物和CO/CO₂二元混合物的吸附选择性。研究结果表明:在0.1 MPa和常温条件下,MOF-74(Ni)材料对CO吸附容量高达6.15 mmol·g^-1,而相同条件下N₂的吸附量只有0.86 mmol·g^-1。MOF-74(Ni)在低压下(0～40 kPa)对CO的吸附量明显高于其对CO₂的吸附量。应用IAST模型估算MOF-74(Ni)对二元混合物吸附选择性的结果表明:MOF-74(Ni)对CO/N₂混合物的吸附选择性在1000以上;MOF-74(Ni)对CO/CO₂的吸附选择性在4～9范围,在所研究的二元气体混合物吸附体系中,MOF-74(Ni)都能优先吸附CO。     

溶剂热浸渍法制备高稳定性Zn(OAc)2/SiO2催化剂及其催化合成苯氨基甲酸甲酯

Zn(OAc)₂对由碳酸二甲酯（DMC）和苯胺合成苯氨基甲酸甲酯（MPC）的反应具有优异的催化性能,但存在易失活、不能重复使用的缺点。为此,以DMC为溶剂,利用溶剂热浸渍法制备Zn(OAc)₂/SiO₂催化剂,并对其催化性能进行了研究。利用XRD、FTIR和TG-DTA等方法对其进行了表征,结果表明,Zn(OAc)₂/SiO₂催化剂表面存在Zn(OAc)₂和ZnO,且其在SiO₂表面分散较好;优化了Zn(OAc)₂/SiO₂催化剂的反应条件,当反应温度为190℃、反应时间为5h、苯胺与DMC的摩尔比为1∶20、催化剂与苯胺质量比为0.2时,苯胺的转化率为97.2%,MPC的选择性为89.4%。和等体积浸渍法制备的催化剂相比,溶剂热浸渍法制备的Zn(OAc)₂/SiO₂催化剂具有较好的稳定性,重复使用7次,苯胺的转化率下降至79.1%,MPC的选择性下降至79.2%。Zn(OAc)₂/SiO₂活性下降的原因是由于ZnO的生成,并对其进行了再生,再生后的催化剂活性与新鲜催化剂接近。     

CO hydrogenation over a rhodium vanadate catalyst: Reduction and regeneration of RhVO4 on SiO2

The hydrogenation of CO over an Rh vanadate (RhVO₄) catalyst supported on SiO₂ (RhVO₄/SiO₂) has been investigated after H₂ reduction at 500°C, and the results are compared with those of vanadia-promoted (V₂O₅–Rh/SiO₂) and unpromoted Rh/SiO₂ catalysts. The mean size of Rh particles, which were dispersed by the decomposition of RhVO₄ after the H₂ reduction, was smaller (41 Å) than those (91–101 Å) of V₂O₅–Rh/SiO₂ and Rh/SiO₂ catalysts. The RhVO₄/SiO₂ catalyst showed higher activity and selectivity to C₂ oxygenates than the unpromoted Rh/SiO₂ catalyst after the H₂ pretreatment. The CO conversion of the RhVO₄/SiO₂ catalyst was much higher than that of V₂O₅–Rh/SiO₂ catalyst, and the yield of C₂ oxygenates increased. We also found that the RhVO₄/SiO₂ catalyst can be regenerated by calcination or O₂ treatment at high temperature after the reaction.     

Catalytic synthesis of methanethiol from hydrogen sulfide and carbon monoxide over vanadium-based catalysts

The direct synthesis of methanethiol, CH₃SH, from CO and H₂S was investigated using sulfided vanadium catalysts based on TiO₂ and Al₂O₃. These catalysts yield high activity and selectivity to methanethiol at an optimized temperature of 615 K. Carbonyl sulfide and hydrogen are predominant products below 615 K, whereas above this temperature methane becomes the preferred product. Methanethiol is formed by hydrogenation of COS, via surface thioformic acid and methylthiolate intermediates. Water produced in this reaction step is rapidly converted into CO₂ and H₂S by COS hydrolysis.

Titania was found to be a good catalyst for methanethiol formation. The effect of vanadium addition was to increase CO and H₂S conversion at the expense of methanethiol selectivity. High activities and selectivities to methanethiol were obtained using a sulfided vanadium catalyst supported on Al₂O₃. The TiO₂, V₂O₅/TiO₂ and V₂O₅/Al₂O₃ catalysts have been characterized by temperature programmed sulfidation (TPS). TPS profiles suggest a role of V₂O₅ in the sulfur exchange reactions taking place in the reaction network of H₂S and CO.     

Selective oxidation of cyclopentene with H_2O_2 by using H_3PW_(12)O_(40) and TBAB as a phase transfer catalyst

The selective oxidation of cyclopentene by aqueous H_2O_2 using H_3PW_(12)O_(40) and tetrabutyl ammonium bromide(TBAB) as a phase transfer catalyst has been investigated. The results show that the presence of TBAB significantly improved the oxidation selectivity of cyclopentene. The effects of the reaction conditions on the conversion of cyclopentene were investigated in detail. The optimal reaction conditions are as follows: the H_3PW_(12)O_(40) to TBAB molar ratio, 1:1–1:3; H_3PW_(12)O_(40) to cyclopentene molar ratio,0.54:100–0.64:100; and molar ratio of H_2O_2 to cyclopentene, 1.6:1. The conversion reached to 59.8% in 4h at 35.0 °C, while the selectivity of glutaraldehyde was 38.0% and the selectivity of 1,2-cyclopentanediol was 55.6%. In addition, a route for oxidation of cyclopentene by aqueous H_2O_2 using a heteropoly acid and quaternary ammonium salt as a phase transfer catalyst was proposed.     

Selective removal of H2S from coke oven gas

The catalytic performance of some metal oxides in the selective oxidation of H₂S in the stream containing water vapor and ammonia was investigated in this study. Among the catalysts tested, V₂O₅/SiO₂ and Fe₂O₃/SiO₂ catalyst showed good conversion of H₂S with very low selectivity to undesired SO₂. Hydrogen sulfide could be recovered as harmless solid products (elemental sulfur and various ammonium salts), and distribution of solid products was varied with types of catalyst and compositions of reactant. XRD and FT-IR analysis revealed that the salt was mixture of ammonium–sulfur–oxygen compounds. It was noteworthy that V₂O₅/SiO₂ catalyst produced elemental sulfur and ammonium thiosulfate, and that elemental sulfur was principal product on Fe₂O₃/SiO₂ catalyst. Small amount of ammonium sulfate was obtained with the Fe₂O₃/SiO₂ catalyst. In order to elucidate the reaction path, the effects of O₂/H₂S ratio and concentration of NH₃ and H₂O are also studied with the V₂O₅/SiO₂ catalyst.     

SBA-15分子筛负载磷钨酸催化合成己二酸

采用SBA-15分子筛等体积浸渍负载磷钨杂多酸制备了PW/SBA-15催化剂,应用XRD、DSG-TGA等对催化剂结构进行分析和表征。结果表明,SBA-15分子筛在负载磷钨酸后,磷钨杂多酸完全引入到SBA-15分子筛的骨架结构中,其稳定性大幅增加。同时采用"一锅煮"的方法用过氧化氢氧化环己烯制得己二酸,运用正交试验法和单因素实验法对催化剂性能进行评价。结果表明,催化剂用量1.75 g、反应时间9 h、反应温度80℃、n(H_2O_2)∶n(环己烯)=5.47∶1,反应开始加入13.75 mL的H_2O_2,4 h后再加入13.75 mL的H_2O_2条件下合成的己二酸收率和纯度最高。     

Performance characteristics of fluidized bed syngas methanation over Ni-Mg/Al2O3 catalyst

The performance characteristics of isothermal fluidized bed syngas methanation for substitute natural gas are investigated over a self-made Ni–Mg/Al2O3 catalyst. Via atmospheric methanation in a laboratory fluidized bed reactor it was clarified that the CO conversion varied in 5% when changing the space velocity in 40–120 L·g?1·h?1 but the conversion increased obviously by raising the superficial gas velocity from 4 to 12.4 cm·s?1. The temperature at 823 K is suitable for syngas methanation while obvious deposition of uneasy-oxidizing Cγoccurs on the catalyst at temperatures around 873 K. From a kinetic aspect, the lowest reaction temperature is suggested to be 750 K when the space velocity is 60 L·g?1·h?1. Raising the H2/CO ratio of the syngas increased proportionally the CO conversion and CH4 selectivity, showing that at enough high H2/CO ratios the active sites on the catalyst are sufficient for CO adsorption and in turn the reaction with H2 for forming CH4. Introducing CO2 into the syngas feed suppresses the water gas shift and Boudouard reactions and thus increased H2 consumption. The ratio of CO2/CO in syngas should be better below 0.52 because varying the ratio from 0.52 to 0.92 resulted in negligible increases in the H2 conversion and CH4 selectivity but decreased the CH4 yield. Introducing steam into the feed gas affected little the CO conversion but decreased the selectivity to CH4. The tested Ni–Mg/Al2O3 catalyst manifested good stability in structure and activity even in syngas containing water vapor.     

H4SiW12O40/SiO2催化正丁醛自缩合反应

正丁醛自缩合合成辛烯醛是工业生产辛醇的重要步骤之一。首先考察了3种杂多酸H₃PW₁₂O₄₀、H₄SiW₁₂O₄₀和H₃PMo₁₂O₄₀对正丁醛自缩合反应的催化性能,发现H₄SiW₁₂O₄₀的催化性能最好。其次,利用浸渍法制备了负载型H₄SiW₁₂O₄₀催化剂,考察了载体和制备条件对催化剂性能的影响,确定以SiO₂为载体,H₄SiW₁₂O₄₀负载量为50%（质量分数）,在150℃焙烧2 h的制备条件。探讨了反应条件对催化剂性能的影响,确定了适宜反应条件：催化剂与正丁醛的质量比为0.15,反应温度120℃,反应时间6 h。在此条件下,正丁醛的转化率为90.4%,辛烯醛的选择性为89.2%。通过对催化剂进行ICP-AES分析和XRD表征,发现活性组分流失是造成催化剂稳定性差的主要原因。为减缓H₄SiW₁₂O₄₀的流失,以[emim]BF₄离子液体为模板剂,采用溶胶-凝胶法制备了H₄SiW₁₂O₄₀/SiO₂催化剂,实验结果表明,催化剂稳定性有一定程度的提高。     

Syngas conversion using RhVO4 and Rh2MnO4 catalysts: Regeneration and redispersion of Rh metal by calcination and reduction treatments

The hydrogenation of CO over mixed oxides (RhVO₄, Rh₂MnO₄) supported on SiO₂ has been studied after H₂ reduction at 300°C and at 500°C, and the results compared with those of unpromoted Rh/SiO₂ catalysts. Rh was more highly dispersed (40 Å) after the decomposition of RhVO₄ by the H₂ reduction than those of Rh₂MnO₄/SiO₂ and unpromoted Rh/SiO₂ catalysts. The activity and the selectivity to C₂ oxygenates of the mixed-oxide catalysts after the H₂ reduction were higher than those of the unpromoted Rh/SiO₂ catalysts, but the activity of the RhVO₄/SiO₂ catalyst increased more dramatically after the decomposition by the H₂ reduction at 300°C, and hence the yield of C₂ oxygenates increased. These results suggest that a strong metal–oxide interaction (SMOI) was induced by the decomposition of the mixed oxides after the H₂ reduction. The catalytic activity and selectivity were reproduced repeatedly by the calcination and reduction treatments of the spent (used) catalyst because of the regeneration of RhVO₄ and redispersion of Rh metal.     

Understanding the mechanism of hydrogen adsorption into metal organic frameworks

Hydrogen adsorption mechanism into MOF-5, a porous metal-organic framework (MOF) has been studied by density functional theory calculation. The selected functionals for the prediction of interaction energies between hydrogen and potential adsorption sites of MOF-5 were utilized after the evaluation with the various functionals for interaction energy of H₂C₆H₆ model system. The adsorption energy of hydrogen molecule into MOF-5 was investigated with the consideration of the favorable adsorption sites and the orientations. We also calculated the second favorable adsorption sites by geometry optimization using every combination of two first adsorbed hydrogen molecules. Based on the calculation of the first and the second adsorption sites and energies, it has been suggested that the hydrogen adsorption into MOF-5 follows a cooperative mechanism in which the metal sites initiate the propagation of the hydrogen adsorption on the whole frameworks. In addition, the interaction mode between the simple benzene ring with hydrogen is significantly changed when the benzene ring has been incorporated into the framework of MOF-5.