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铁系复合氧化物催化性质的研究 总被引:1,自引:0,他引:1
合成出一系列La_(1-s)A′_sFeO_3(A′=Ca、Sr、Ba;0≤2≤1)复合氧化物催化剂,并研究了Ca、Sr、Ba部分取代La后催化剂对CO氧化活性的影响。以XRD测定其晶体结构。结果表明,除含Ca>0.5和Ba=1.0外均生成钙钛矿型结构。用XPS和TPD法研究了吸附性能。指认吸附氧是CO氧化的活性物种,并初步解释了活性规律的成因。 相似文献
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二维(2D)沸石与三维(3D)沸石的制备及催化研究进展 总被引:1,自引:0,他引:1
如今在能源紧缺和“双碳”背景下, 能源清洁高效利用显得异常重要. 沸石催化剂是在能源加工过程中提高产出和品质的重要手段, 现已成为该领域的研究热点. 随着对沸石研究的进一步深入, 它们的性质和结构逐渐清晰, 广泛应用于催化、吸附、分离等行业. 独特晶体结构的二维沸石, 它们的片层结构在降低分子传输路径的同时, 可增大活性位点的可及性, 降低了积碳率, 具有较大应用潜力. 此外, 通过改变结构导向剂的结构可以拓宽二维沸石的种类, 符合工业上适应范围广的特点. 在此, 综述了两种维度分子筛的发展过程, 阐明了它们在不同领域中催化转化的构-效关系, 以及二维沸石的制备路径. 整理了合成机理并分析了二维沸石在比表面积和活性位点可及性上的优势, 为二维沸石分子筛在工业中的应用提供借鉴. 相似文献
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Evaluation and optimization of the metal‐binding properties of a complex ligand for immobilized metal affinity chromatography
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Bin Chen Rong Li Shiyu Li Xiaoli Chen Kaidi Yang Guoliang Chen Xiaoxun Ma 《Journal of separation science》2016,39(3):518-524
The simultaneous determination of two binding parameters for metal ions on an immobilized metal affinity chromatography column was performed by frontal chromatography. In this study, the binding parameters of Cu2+ to l ‐glutamic acid were measured, the metal ion‐binding characteristics of the complex ligand were evaluated. The linear correlation coefficients were all greater than 99%, and the relative standard deviations of two binding parameters were 0.58 and 0.059%, respectively. The experiments proved that the frontal chromatography method was accurate, reproducible, and could be used to determine the metal‐binding parameters of the affinity column. The effects of buffer pH, type, and concentration on binding parameters were explored by uniform design experiment. Regression, matching and residual analyses of the models were performed. Meanwhile, the optimum‐binding conditions of Cu2+ on the l ‐glutamic acid‐silica column were obtained. Under these binding conditions, observations and regression values of two parameters were similar, and the observation values were the best. The results demonstrated that high intensity metal affinity column could be effectively prepared by measuring and evaluating binding parameters using frontal chromatography combined with a uniform design experiment. The present work provided a new mode for evaluating and preparing immobilized metal affinity column with good metal‐binding behaviors. 相似文献
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D Shu X Li M Zhang PJ Robichaux IA Guzei W Tang 《The Journal of organic chemistry》2012,77(15):6463-6472
We have developed two different types of tandem reactions for the synthesis of highly functionalized cyclohexenones from cyclopropyl substituted propargyl esters. Both reactions were initiated by rhodium-catalyzed Saucy-Marbet 1,3-acyloxy migration. The resulting cyclopropyl substituted allenes derived from acyloxy migration then underwent [5 + 1] cycloaddition with CO. The acyloxy group not only eased the access to allene intermediates but also provided a handle for further selective functionalizations. 相似文献
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Shu XZ Li X Shu D Huang S Schienebeck CM Zhou X Robichaux PJ Tang W 《Journal of the American Chemical Society》2012,134(11):5211-5221
A new type of rhodium-catalyzed [5 + 2] cycloaddition was developed for the synthesis of seven-membered rings with diverse functionalities. The ring formation was accompanied by a 1,2-acyloxy migration event. The five- and two-carbon components of the cycloaddition are 3-acyloxy-1,4-enynes (ACEs) and alkynes, respectively. Cationic rhodium(I) catalysts worked most efficiently for the intramolecular cycloaddition, while only neutral rhodium(I) complexes could facilitate the intermolecular reaction. In both cases, electron-poor phosphite or phosphine ligands often improved the efficiency of the cycloadditions. The scope of ACEs and alkynes was investigated in both the intra- and intermolecular reactions. The resulting seven-membered-ring products have three double bonds that could be selectively functionalized. 相似文献
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二冲程汽油机排气污染严重,尤其是燃烧混合油,浓混合气时有害物排放量时。着火时刻火焰光谱分析表明,CH(431.5nm)及C2(516.5nm)自由基光强峰值比较强,尤其是CN(387nm)自由基光强峰值比较突出。根据Fenimore机理可以解释排气中NOx的生成机理。这一点也为日本Nagase的试验所验证。 相似文献
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Huang S Li X Lin CL Guzei IA Tang W 《Chemical communications (Cambridge, England)》2012,48(16):2204-2206
A Rh-catalyzed 1,3-acyloxy migration of propargyl ester followed by intramolecular [4+2] cycloaddition of vinylallene and unactivated alkyne was developed. This tandem reaction provides access to bicyclic compounds containing a highly functionalized isotoluene or cyclohexenone structural motif, while only aromatic compounds were observed in related transition metal-catalyzed cycloadditions. 相似文献