Fe助剂对CuO/SiO_2-MgO催化剂结构和甲醛乙炔化性能的影响

为开发绿色无污染、经济性能优良的炔化催化剂,采用共沉淀法制备一种新型的Cu OFe O/Si O2-Mg O催化剂,采用电感耦合等离子体发射光谱仪、低温N2物理吸附-脱附、X射线衍射、H2程序升温还原对催化剂组成、结构及织构进行表征,研究Fe助剂对Cu O/Si O2-Mg O催化剂结构及炔化性能的影响。结果表明,与催化剂Cu O/Si O2-Mg O相比,Fe O的引入使催化剂中Cu O的可还原性提高,在反应过程中Cu O更易生成活性物种Cu+的炔化物,Cu O-Fe O/Si O2-Mg O催化剂表现出较高的甲醛乙炔化性能。     

核壳结构CuO-Bi_2O_3@meso-SiO_2催化剂的制备及甲醛乙炔化性能

为了提高铜铋炔化催化剂的稳定性、抑制活性组分流失造成的活性下降和延长催化剂使用寿命,采用共沉淀法制备Cu O-Bi2O3粉体,并使用溶胶-凝胶法对其进行包覆制备核壳结构Cu O-Bi2O3@meso-Si O2催化剂,利用XRD、低温N2物理吸附-脱附和TEM对其织构和结构进行表征,考察在甲醛乙炔化反应中的催化活性和稳定性。结果表明,核壳结构催化剂整体外观呈球形,Si O2包覆层为有序介孔结构。与工业催化剂和未包覆的Cu O-Bi2O3粉体相比,核壳结构Cu O-Bi2O3@meso-Si O2催化剂在甲醛乙炔化反应中表现出更优异的稳定性。     

磁性CuO—Bi2O3催化剂的制备及炔化性能

采用溶胶凝胶法结合等体积浸渍法制备了具有磁性的CuO—Bi2O3／Fe3O4@SiO2催化剂,利用XRD、BET等手段进行表征,并考察了催化剂在甲醛乙炔化反应中的催化性能。结果表明,载体Fe3O4@SiO2具有较高的比表面积,CuO在其表面以高分散的微晶态形式存在;制得的催化剂在甲醛乙炔化反应中有较高的活性与使用稳定性,可以在外加磁场的作用下与反应液快速分离。     

用于二乙醇胺脱氢的Cu/ZnO/Al2O3/ZrO2催化剂的制备与表征

以氢氧化钠为沉淀剂,硝酸铜、硝酸锌、硝酸铝和硝酸氧锆为原料,采用共沉淀法制备出了用于二乙醇胺脱氢制亚氨基二乙酸的Cu/ZnO/Al2O3/ZrO2催化剂,并用物理吸附(BET)和X射线衍射(XRD)对不同种类的铜基催化剂进行了表征,探讨了ZnO和Al2O3的不同比例对催化剂性能的影响。结果表明,同时加入ZnO和Al2O3的Cu/ZnO/Al2O3/ZrO2催化剂具有大的比表面积,Cu/ZnO/Al2O3/ZrO2催化剂具有非晶态结构。该催化剂适宜的反应条件为:w(NaOH)=30%、反应温度160℃、压力1.0 MPa,二乙醇胺转化率可达100%,亚氨基二乙酸收率可达95.61%。     

Al_2O_3-ZrO_2复合氧化物对Cu基催化剂选择加氢性能的影响

采用共沉淀法制备Al2O3-ZrO2复合氧化物,并以此为载体制备负载型Cu基催化剂,运用X射线衍射、X射线能谱、扫描电子显微镜对载体和催化剂进行表征。以糠醛气相加氢制糠醇反应为探针,考察复合氧化物对Cu基催化剂选择加氢活性的影响。结果表明,Al2O3-ZrO2复合氧化物中ZrO2的存在会减少CuO与Al2O3的接触,降低Cu基催化剂的深加氢能力;Al2O3有助于延迟ZrO2的晶化,避免活性组分Cu嵌入到ZrO2晶格中导致催化活性下降。载体中ZrO2质量分数为20%时,Cu/Al2O3-ZrO2催化剂选择加氢活性最高,与Cu/Al2O3催化剂相比,该催化剂具有较好的低温加氢活性和高温加氢选择性。     

Cu/Bi/Al2O3催化剂制备及表征

在室温到 5 0℃范围内及不同的焙烧条件下采用共沉淀法和浸渍法制备Cu/Al2 O3催化剂和Cu/Bi/Al2 O3催化剂 ,并对催化剂进行了XRD、FT -IR表征。     

丙三醇水蒸气重整制氢M/Al2O3催化剂

以Al2O3为载体,采用浸渍法制备了Cu、Co、Ni、Pt/Al2O3四种单一组分催化剂(M/Al2O3)。研究了M/Al2O3催化剂对丙三醇水蒸气重整制氢反应的适用性及反应行为;考察了制备条件及还原条件,通过活性、稳定性及抗积炭性进行了催化剂的活性评价,并对催化剂进行了TPR、XRD表征。研究发现M/Al2O3催化剂用于丙三醇水蒸气重整制氢均表现出一定活性;其中Cu/Al2O3催化剂具有一定的抗积炭性;Pt/Al2O3催化剂表现出较好的抗积炭性、高温活性,但稳定性较差;Co/Al2O3催化剂表现出较好的稳定性;Ni/Al2O3催化剂表现出较好的低温活性。     

CuNi/Al2O3催化剂上乙炔选择加氢的研究

采用浸渍法制备了CuNi/Al2O3催化剂,研究了Ni负载量、Cu负载量及n(Cu)/n(Ni)对催化剂上乙炔选择加氢活性和选择性的影响,以及催化剂的还原性能。结果表明:CuNi/Al2O3催化剂中Cu提高了Ni的还原性,使催化剂具有很高的活性及乙烯选择性。随Cu/Ni原子比的提高,催化剂的活性下降,选择性升高,当Ni的负载量为10%、n(Cu)/n(Ni)=0.5时,在反应温度为50℃、反应压力为0.2 MPa、原料气流量为45 mL/min及H2流量为1.5 mL/min的反应条件下,乙炔的转化率达88.98%,乙烯的选择性达74.01%,乙烯收率为65.86%。     

甲醛乙炔化反应中CuO-Bi2O3/SiO2-MgO催化剂活化过程研究

甲醛与乙炔发生炔化反应合成1,4-丁炔二醇,选用铜铋作为催化剂。模拟最具代表性的工业炔化催化剂以研究甲醛乙炔化反应的活化过程,制备高性能CuO-Bi₂O₃/SiO₂-MgO催化剂,结合XRD、H₂-TPR、TG-DTA和N₂-TPD-MS等表征,研究炔化催化剂活化过程中铜物种的转变,获得最优催化剂活化方法。结果表明,CuO在甲醛溶液中无乙炔存在下可定向转化为Cu₂O,但经乙炔活化后活性较低,归因于还原过程中Cu物种的流失及晶粒长大。而在甲醛与乙炔协同作用下,CuO可快速转变为Cu的炔化物种,表现出较高的炔化活性。表明炔化催化剂的活化过程必须在甲醛与乙炔同时存在的条件下进行。     

锰和镧助剂对二乙醇胺氧化脱氢制亚氨基二乙酸Cu/ZrO2催化剂的改性作用

采用共沉淀法制备了掺杂锰、镧的Cu/ZrO2催化剂,考察了锰和镧助剂对Cu/ZrO2催化二乙醇胺氧化脱氢制亚氨基二乙酸性能的影响。采用XRD(X射线粉末衍射),TPR(程序升温还原),N2O滴定,N2吸附-脱附等方法考察了助剂改性后催化剂的结构和表面性质的变化。结果表明,引入锰助剂后催化剂比表面积从105 m2.g-1增大到143 m2.g-1,活性Cu的分散度从36.5%提高到53.6%;镧助剂的引入阻滞了金属Cu的聚集长大,延缓了催化剂晶化速度;锰、镧共同引入时表现出协同作用,不但使活性Cu的分散度提高,同时催化剂晶化速度减慢,从而提高了催化剂循环使用性能。     

Cu2O/TiO2催化甲醛乙炔化反应的载体效应

以不同温度焙烧的TiO₂为载体,CuCl₂·2H₂O为铜源,NaOH为沉淀剂,L-抗坏血酸钠为还原剂,采用液相还原-沉积沉淀法制备了Cu₂O/TiO₂,借助X射线粉末衍射（XRD）、H₂程序升温还原（H₂-TPR）、N₂-物理吸附、透射电镜（TEM）、X射线光电子能谱（XPS）等手段,研究了TiO₂载体焙烧温度对Cu₂O/TiO₂甲醛乙炔化反应性能的影响。结果表明,低温焙烧得到的TiO₂载体以锐钛矿相存在,与Cu₂O物种间具有弱的相互作用,使得Cu₂O被过度还原为金属Cu,催化活性较低。随着载体焙烧温度的升高,TiO₂中出现金红石相,Cu₂O与载体间相互作用增强,Cu₂O高效转变为乙炔亚铜活性物种,使催化剂表现出最佳的催化性能。     

The oxidation of carbon monoxide at ambient temperature over mixed copper–silver oxide catalysts

Cu₂Ag₂O₃ has been prepared by a precipitation method and evaluated for ambient temperature carbon monoxide oxidation. The Cu₂Ag₂O₃ catalyst demonstrated appreciable activity and a relationship with preparation ageing time was observed. An ageing time of 4 h produced a catalyst with the highest oxidation performance. The catalyst precursor materials, prepared by drying at room temperature, displayed initial high activity, which decreased with time on line. The precursors were transformed during CO oxidation to form the mixed oxide Cu₂Ag₂O₃ as the material was dried in situ. A comparison of the catalytic activity has been made with a representative sample of a high activity hopcalite, mixed copper/manganese oxide catalyst. On the basis of CO oxidation rate data corrected for the effect of catalyst surface area the Cu₂Ag₂O₃, aged for 4 h was at least as active as the hopcalite catalyst.     

Photocatalytic activity of Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions

Cu₂O/TiO₂, Bi₂O₃/TiO₂ and ZnMn₂O₄/TiO₂ heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu₂O, Bi₂O₃ and ZnMn₂O₄ are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu₂O/TiO₂ and Bi₂O₃/TiO₂ by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed.     

双膜强化类Fenton工艺处理制浆废水的研究

类Fenton工艺又称非均相Fenton工艺,主要用于降解废水COD,可避免传统Fenton工艺产生的铁泥问题,但双氧水利用率尚有待提高。采用1个陶瓷膜分布H₂O₂,另1个陶瓷膜分离催化剂,构成双膜促进的非均相Fenton新工艺,考察了不同催化剂对制浆废水中COD的降解效果,优化了H₂O₂进料速率和反应渗透通量,分析了催化剂的稳定性和陶瓷膜污染情况。结果表明,自制立方体结构的Cu₂O对制浆废水中COD降解效果最佳,当Cu₂O添加量为1 g·L^-1,H₂O₂加入量为0.8 ml·L^-1,反应温度为30℃,反应渗透通量为137 L·m^-2·h^-1时,RO（Ⅰ）～RO（Ⅳ）4种废水的COD降解量分别为11、130、291和417 mg·L^-1,H₂O₂的利用率分别为9%、106%、232%、334%,H₂O₂利用率大于100%的主要原因是废水中大量的氯离子与铜催化剂作用产生氯自由基参与了降解反应,COD降解量与Cl-含量呈现线性关系,并且COD降解率随膜渗透通量的减小而增大。360 min的连续运行表明陶瓷膜分布器在非均相Fenton反应过程中会形成可逆滤饼层,膜污染较小,COD降解率稳定保持在65%以上。随着制浆废水中盐浓度的增大,Cu₂O催化剂稳定性变差,Cu离子的溶出量增大。陶瓷膜可以强化非均相Fenton工艺处理制浆废水效果,提高双氧水的利用率和连续运行的稳定性。     

稻壳白炭黑负载Fe2O3的气相芬顿反应NO预氧化

以稻壳为硅源,采用直接煅烧法制备白炭黑,以其为载体,采用共浸渍法制备Fe₂O₃/SiO₂催化剂;并采用同样方法以商用二氧化硅为载体制备Fe₂O₃/C-SiO₂催化剂,将二者用于催化H₂O₂预氧化NO的实验。探究不同工况（负载量、催化温度、H₂O₂汽化温度、H₂O₂流量和水汽浓度）对NO预氧化的影响,并对催化剂进行表征,分析其物理化学性质对催化性能的影响。结果表明,在负载量为50%、催化温度为140℃、H₂O₂汽化温度为120℃、H₂O₂流量为2.5mL/h时,达到最佳工况,NO氧化度能达到73%;在相同实验条件下Fe₂O₃/SiO₂催化剂的预氧化效果要比Fe₂O₃/C-SiO₂催化剂高20%左右。TPR结果表明载体可以降低活性组分的还原温度,减少活性组分的团聚;催化剂的晶相结构稳定,机械强度及热稳定性良好;ESR和XPS结果显示Fe₂O₃/SiO₂催化剂的催化性能优于Fe₂O₃/C-SiO₂催化剂,能够更好地催化分解H₂O₂产生·OH。     

钇掺杂三氧化二铁催化剂的脱硝性能研究

为提升三氧化二铁(Fe₂O₃)催化剂的脱硝性能,扩展催化剂的活性温度窗口,采用共沉淀法引入助剂钇(Y)元素对Fe₂O₃催化剂进行改性。通过X射线衍射(XRD)、氮气等温吸-脱附(N₂-BET)、X射线光电子能谱(XPS)、氨气程序升温脱附(NH₃-TPD)、氢气程序升温还原(H₂-TPR)等表征方法对样品进行了表征分析。XRD和N₂-BET结果表明,Y的掺杂使催化剂结构发生变化,比表面积增加、孔径减小。XPS和NH₃-TPD结果证明,Y掺杂Fe₂O₃具有更多的表面吸附氧(O_Ⅰ)、Fe²⁺以及更多的酸量。H₂-TPR结果表明,Y的掺杂使催化剂的氧化还原能力略有下降。测试了不同含量Y掺杂的Fe₂O₃催化剂在150～400℃的脱硝性能,其中Fe<...     

微波热解制备g-Fe2O3催化剂及其SCR脱硝性能

以FeSO₄·7H₂O[Fe(NO₃)₃·9H₂O]为铁源,采用新型微波热解法制备γ-Fe₂O₃[a-Fe₂O₃]催化剂样品,通过XRD、N₂等温吸附-脱附、压汞法等实验手段对催化剂样品晶相、微观孔结构等进行表征;考察两种催化剂样品的NH₃-SCR脱硝性能,通过归一化处理得到两种催化剂在不同温度下的本征脱硝反应速率,同时对比研究了γ-Fe₂O₃与钒系催化剂的脱硝活性;研究氨氮比、氧浓度等运行参数对γ-Fe₂O₃催化剂NH₃-SCR脱硝性能的影响规律,并对其抗硫抗水性能进行考察.结果表明:采用新型微波热解法可得到纯度较高的γ-Fe₂O₃催化剂,其介孔分布合理且大孔数量丰富;同时γ-Fe₂O₃催化剂表现出优于a-Fe₂O₃催化剂的脱硝性能,400℃时最大NO_x转化率达到96%,300、325、350℃下单位面积脱硝速率达到a-Fe₂O₃催化剂的3倍左右;γ-Fe₂O₃催化剂具备优良的抗硫抗水性能,其最佳氨氮比为1、最佳氧体积分数为3.5%.     

Effects of iron precursors on the structure and catalytic performance of iron molybdate prepared by mechanochemical route for methanol to formaldehyde

Mechanochemical synthesis has been applied for many novel material preparations and gained more and more attention due to green and high-efficiency recently. In order to explore the influences of iron precursors on structure and performance of iron molybdate catalyst prepared by mechanochemical route, three typical and cheap iron precursors have been used in preparation of iron molybdate catalyst. Many characterization methods have been employed to obtain the physical and chemical properties of iron molybdate catalyst. Results indicate that iron precursors have the significant impact on the phase composition, crystal morphology and catalytic performance in the conversion of methanol to formaldehyde. It is hard to regulate the phase composition by changing Mo/Fe mole ratios for Fe_2(SO_4)_3 as iron precursor. In addition, as for Fe_2(SO_4)_3, the formaldehyde yield is lower than that from iron molybdate catalyst prepared with Fe(NO_3)_3·9H_2O due to the reduction in Fe_2(MoO_4)_3 phase as active phase. Based on mechanochemical and coprecipitation method, the solvent water could be a key factor for the formation of MoO_3 and Fe_2(MoO_4) for FeCl_3·6H_2O and Fe_2(SO_4)_3 as precursors. Iron molybdate catalyst prepared with Fe(NO_3)_3·9H_2O by mechanochemical route, shows the best methanol conversion and formaldehyde yield in this reaction.     

Enhanced activity of metal oxide-doped Ga2O3–Al2O3 for NO reduction by propene

Effect of additives, In₂O₃, SnO₂, CoO, CuO and Ag, on the catalytic performance of Ga₂O₃–Al₂O₃ prepared by sol–gel method for the selective reduction of NO with propene in the presence of oxygen was studied. As for the reaction in the absence of H₂O, CoO, CuO and Ag showed good additive effect. When H₂O was added to the reaction gas, the activity of CoO-, CuO- and Ag-doped Ga₂O₃–Al₂O₃ was depressed considerably, while an intensifying effect of H₂O was observed for In₂O₃- and SnO₂-doped Ga₂O₃–Al₂O₃. Of several metal oxide additives, In₂O₃-doped Ga₂O₃–Al₂O₃ showed the highest activity for NO reduction by propene in the presence of H₂O. Kinetic studies on NO reduction over In₂O₃–Ga₂O₃–Al₂O₃ revealed that the rate-determining step in the absence of H₂O is the reaction of NO₂ formed on Ga₂O₃–Al₂O₃ with C₃H₆-derived species, whereas that in the presence of H₂O is the formation of C₃H₆-derived species. We presumed the reason for the promotional effect of H₂O as follows: the rate for the formation of C₃H₆-derived species in the presence of H₂O is sufficiently fast compared with that for the reaction of NO₂ with C₃H₆-derived species in the absence of H₂O. Although the retarding effect of SO₂ on the activity was observed for all of the catalysts, SnO₂–Ga₂O₃–Al₂O₃ showed still relatively high activity in the lower temperature region.     

磁性CuO-Bi2O3/Fe3O4-SiO2-MgO催化剂的制备及甲醛乙炔化性能

采用浸渍法和共沉淀法制备了一系列不同Cu含量的超顺磁CuO-Bi₂O₃/Fe₃O₄-SiO₂-MgO催化剂。使用电感耦合等离子体发射光谱仪(ICP-AES)、低温N₂物理吸-脱附、X射线衍射(XRD)、H₂程序升温还原(H₂-TPR)、振动样品磁强计(VSM)对催化剂的组成、结构、织构及磁性能进行表征, 评价了该催化剂催化甲醛乙炔化合成1, 4-丁炔二醇的催化活性。结果表明, 制备方法对催化剂中活性组分CuO的存在状态及炔化性能有较大影响, 采用共沉淀法较浸渍法制备的催化剂具有更高的比表面积、CuO分散度与较好的还原能力, 表现出较高的炔化性能;Cu含量是影响催化剂炔化性能的另一重要因素, 随Cu含量的增加, 催化剂活性逐渐增加, 在本研究考察范围内, 以共沉淀法制备的Cu质量分数为30%的催化剂表现出最佳的甲醛乙炔化性能。同时, 该催化剂具有良好的超顺磁性, 可以在外加磁场的作用下迅速分离回收, 循环使用6次后, 其催化活性明显高于非磁性催化剂。