多孔碳负载Cu_2O/Cu双相催化剂的制备及应用

以硝酸铜和均苯三甲酸为原料,采用溶剂热合成法制备了金属有机框架材料(Cu-BTC),将其在氮气和空气气氛下焙烧制备了多孔碳负载的Cu2O/Cu催化剂Cu-BTC-1和Cu-BTC-2,并考察了其在对硝基苯酚催化还原中的催化性能。对Cu-BTC-1和Cu-BTC-2进行了XRD,SEM,TEM和BET表征。XRD表征结果表明:在氮气气氛中焙烧Cu-BTC可得到多孔碳负载的Cu2O/Cu双相纳米晶材料。SEM和TEM结果表明:相对于Cu-BTC-2催化剂,Cu-BTC-1双相粒子粒径较小,介于10~30 nm之间,比表面积较高,达200 m~2/g。对硝基苯酚催化还原实验结果表明:与Cu-BTC-2(表观速率系数kapp=0.0067 s–1)相比,Cu-BTC-1在对硝基苯酚的还原中具有更高的催化活性(kapp=0.0108 s–1)。     

CeO_2形貌对甲醇水蒸汽重整CuO/CeO_2催化剂的影响

通过改变焙烧气氛,通过水热法合成不同形貌的CeO_2纳米材料,再通过浸渍法将其制备成CuO/CeO_2催化剂,并应用于甲醇水蒸汽重整制氢反应。采用SEM、XRD、BET、H2-TPR、N2O滴定和XPS对催化材料进行了表征,着重探讨了氧化铈形貌对催化剂结构、性质和性能的影响。结果表明:空气气氛下焙烧得到的纳米棒状结构的CeO_2负载CuO制备的CuO/CeO_2催化剂性能最佳,这主要是因为纳米棒状结构的CeO_2与CuO的相互作用较强,表面存在较多的晶格缺陷和氧空穴,进而使得CuO/CeO_2催化剂表相Cu含量增加,Cu物种的还原温度较低,催化活性较好。当反应温度为260℃、n(水)/n(甲醇)=1.2、甲醇气体空速为800h–1时,甲醇转化率可达100%。     

纳米尖晶石CuFe_xCo_(2-x)O_4的制备及其在对硝基苯酚催化还原中的应用

目前,水质污染特别是对硝基苯酚造成的水质污染正受到越来越多的重视和关注。为了解决这一问题,提出了一种催化还原对硝基苯酚转化为对氨基苯酚的方法,而还原过程中一般都需要活性高、易回收的催化剂。本文采用凝胶-燃烧法制备了一系列易回收的CuFe_xCo_(2-x)O_4纳米尖晶石催化剂(CuFe_2O_4、CuFeCoO_4和CuCo_2O_4),并系统探究了催化剂在对硝基苯酚催化还原中的催化活性。XRD表征表明,催化剂CuFe_2O_4、CuFeCoO_4、CuCo_2O_4属于尖晶石结构。通过扫描电镜对比了纳米尖晶石催化剂CuFe_2O_4、CuFeCoO_4、CuCo_2O_4的微观形貌,相对于催化剂CuFe_2O_4、CuFeCoO_4,纳米尖晶石CuCo_2O_4催化剂具有更小的粒径和分散度。催化还原对硝基苯酚的实验结果表明,相对于催化剂CuCoFeO_4和CuFe_2O_4,纳米尖晶石CuCo_2O_4催化剂在对硝基苯酚的还原中具有更高的催化活性和良好的应用前景。     

MOF作模板制备多孔Au/Cu_xO催化剂及其CO氧化性能

采用MOF材料作模板,通过在Cu-BTC材料表面预先负载贵金属Au再热解的方法,成功制备了具有正八面体结构的新型多孔Au/Cu_xO负载型催化剂。通过降低热解环境中的O_2浓度,调节氧化时间,实现了Au/Cu-BTC氧化产物组分的调节,分别制得了Au/Cu_2O、Au/Cu_2O-Cu O、Au/CuO复合催化材料。将其用于CO催化氧化,发现所有Au/Cu_xO催化剂都表现出比Cu-BTC和Au/Cu-BTC更优异的催化性能,其中由于拥有较高的比表面积、Cu_2O含量以及更好的Au的分散性,Au/Cu_2O的CO氧化活性最佳,180℃即能实现CO的完全转化。     

氧化铈形貌对甲醇水蒸气重整制氢CuO/CeO2催化剂性能的影响

采用简单的改变焙烧气氛的方法改变水热法合成的CeO2纳米材料的形貌,得到的CeO2纳米材料再通过浸渍法制备CuO/CeO2催化剂,并将其应用于甲醇水蒸汽重整制氢反应。采用SEM、XRD、BET、H2-TPR、N2O滴定和XPS等对催化材料进行了表征,着重探讨了氧化铈形貌对催化剂结构、性质和性能的影响。结果表明,纳米棒状结构的CeO2负载CuO后得到的CuO/CeO2催化剂性能最佳,这主要是因为纳米棒状结构的CeO2与CuO的相互作用较强,表面存在较多的晶格缺陷和氧空穴,进而使得CuO/CeO2催化剂表相Cu含量增加,Cu物种的还原温度较低,催化活性较好。当反应温度为260 °C、水醇物质的量比为1.2、甲醇气体空速为800 h-1时,甲醇转化率可达100%,重整气中CO摩尔含量为0.16%。     

载体对镍系催化剂催化对硝基苯酚加氢制对氨基苯酚的影响

采用浸渍法制备了Ni/Al2O3、Ni/TiO2、Ni/活性炭和Ni/硅藻土等一系列镍系催化剂,研究了其催化对硝基苯酚加氢制备对氨基苯酚的活性.负载型镍系催化剂具有单一的对氨基苯酚选择性.不同载体负载的催化剂上对硝基苯酚的转化率顺序为:Ni/活性炭>Ni/硅藻土>Ni/TiO2Ni/Al2O3.高比表面积以及金属镍在活性炭上的良好分散性使得Ni/活性炭催化活性最高;NiO与硅藻土间弱相互作用,有助于提高活性;而NiO与Al2O3之间存在相互作用抑制了还原后金属镍的催化加氧活性.     

制备条件对Cu/Al2O3 选择性催化还原NO的影响研究

考察了制备方法、活性组分负载量和焙烧温度对Cu/Al₂O₃ 选择性催化还原NO的影响。结果表明，采用溶胶-凝胶+浸渍法制备的Cu/Al₂O₃催化剂活性最好；负载Cu质量分数为15%时，催化剂的活性温域最宽，最大活性温度最低，催化活性最好；最佳焙烧温度为750 ℃。     

超临界CO_2制备h-BN纳米片及其负载钴催化性能研究

利用超临界二氧化碳(SC CO_2)技术剥离块状h-BN,制备氮化硼纳米片(BNNSs),并将钴纳米粒子负载在BNNSs上,得到催化剂Co/BNNSs,并通过XRD、FT-IR和SEM对两者的结构和形貌进行表征。以对硝基苯酚的催化还原反应为模型考察催化剂的催化性能,经过5次循环后,还原活性无明显降低,对硝基苯酚的还原率仍在80%以上。因此,Co/BNNSs催化剂具有良好的稳定性和催化还原对硝基苯酚的性能。     

焙烧温度对Cu/Zn/Al催化剂超临界甲醇中木质素液化的影响

采用共沉淀法制备类层柱Cu/Zn/Al水滑石,经焙烧制备Cu/Zn/Al催化剂。考察了焙烧温度对催化剂在超临界甲醇中木质素催化液化活性及稳定性的影响。结果表明,500℃焙烧时水滑石分解较为完全,析出的ZnO和ZnAl2O4尖晶石相对析出的CuO纳米粒子起到良好的隔离和稳定作用;在340℃、80 mg木质素、30 mg催化剂、4 mL甲醇反应3 h条件下进行重复性实验,500℃焙烧催化剂表现出良好的活性和稳定性。     

不同还原剂对Ag@Fe_3O_4催化剂微观结构与催化性能的影响

采用共沉淀法制备了磁性纳米粒子Fe_3O_4,然后以硼氢化钠和水合肼两种还原剂制备了一系列Ag@Fe_3O_4负载型催化剂,并系统考察了该催化剂在对硝基苯酚还原中的催化性能。XRD和SEM表征表明,Fe_3O_4负载的Ag纳米粒子属于晶态结构,且硼氢化钠还原得到的Fe_3O_4负载银粒子分布更加均匀,尺寸明显更小。对硝基苯酚催化还原实验表明,在相同的制备条件下硼氢化钠还原制备的Ag@Fe_3O_4催化剂较水合肼还原得到Ag@Fe_3O_4催化剂具有更高的催化活性,这主要源于硼氢化钠还原得到负载银粒子具有更加优化的微观结构和分布状态。     

Comparative Study on Catalytic Properties for Low-Temperature CO Oxidation of Cu/CeO2 and CuO/CeO2 Prepared via Solvated Metal Atom Impregnation and Conventional Impregnation

Cu/CeO₂ and CuO/CeO₂ catalysts were prepared by solvated metal atom impregnation (SMAI) and conventional impregnation (CI) and used for carbon monoxide oxidation in CO and air. The catalysts were characterized by means of XRD, XPS, AES and H₂-TPR techniques. The Cu/CeO₂ catalyst prepared via SMAI exhibits higher catalytic activity in CO oxidation than that prepared via CI with the same Cu content due to the smaller Cu particles. The CuO/CeO₂ catalyst prepared via SMAI also shows higher catalytic activity than that prepared via CI because the CuO particles of the former are smaller than the latter and can be reduced by CO more easily. The Cu/CeO₂ catalysts display higher catalytic activities than CuO/CeO₂ catalysts with the same Cu content and prepared by the same method. The TPR profile for CuO/CeO₂ catalyst prepared via SMAI has a single peak, indicating a one-step reduction, whereas the TPR profile for CuO/CeO₂ catalyst prepared via CI has two peaks, indicating a two-step reduction due to the existence of two kinds of CuO species.     

Binary [Cu2O/MWCNT] and ternary [Cu2O/ZnO/MWCNT] nanocomposites: formation, characterization and catalytic performance in partial ethanol oxidation

Cuprous oxide agglomerates composed of 4-10 nm Cu2O nanoparticles were deposited on multiwalled carbon nanotubes (MWCNTs) and on ZnO/MWCNTs to give binary [Cu2O/MWCNT] and ternary [Cu2O/ZnO/MWCNT] composites. Di-aqua-bis[2-(methoxyimino)propanoato]copper Cu[O2CCCH3NOMe](2)·2H2O 1 in DMF was used as single source precursor for the deposition of nanoscaled Cu2O. The precursor decomposes either in air or under argon to yield CuO2 by in situ redox reaction. Thermogravimetric coupled mass spectroscopic analysis (TG-MS) of 1 revealed that methanol formed during the decomposition of 1 acts as a potential in situ reducing agent. Scanning electron microscopy (SEM) of the binary [Cu2O/MWCNT] nano-composite shows an increase of cuprous oxide loading depending on the precursor amount, along the periphery of the MWCNTs as well as formation of larger particle agglomerates. Transmission electron microscopy (TEM) of the sample shows crystalline domains of size 4-10 nm surrounded by an amorphous region within the larger particles. SEM and TEM of ternary [Cu2O/ZnO/MWCNT] clearly reveal that Cu2O nanoparticles are primarily deposited on ZnO rather than on MWCNTs. The catalytic activities of the [Cu2O/MWCNT] and [Cu2O/ZnO/MWCNT] binary and ternary composites were studied for the selective partial oxidation of ethanol to acetaldehyde with molecular oxygen. While using binary [Cu2O/MWCNT] (13.8 wt% Cu) as catalyst, acetaldehyde was obtained with a yield of 87% at 355 °C (selectivity 96% and conversion 91%). When nanoscale ZnO is present, the resulting [Cu2O/ZnO/MWCNT] composite shows preferential hydrogen and CO2 formation due to the fact that the dehydrogenation and total oxidation pathway is more favoured compared to the binary composite. Significant morphological changes of the catalyst during the catalytic process were observed.     

CO<Subscript>2</Subscript> hydrogenation to methanol over Cu/ZnO catalysts synthesized via a facile solid-phase grinding process using oxalic acid

Reduced Cu/ZnO catalyst was synthesized through solid phase grinding of the mixture of oxalic acid, copper nitrate and zinc nitrate, followed by subsequent calcination in N₂ atmosphere without further H₂ reduction. The catalysts were characterized by various techniques, such as XRD, TG-DTA, TPR and N₂O chemisorption. Characterization results suggested that during the calcination in N₂, as-ground precursor (oxalate complexes) decomposed to CuO and ZnO, releasing considerable amount of CO, which could be used for in situ reduction of CuO to Cu^o. The in situ reduced O/I-Cu/ZnO catalyst was evaluated in CO₂ hydrogenation to methanol, which exhibited superior catalytic performance to its counterpart O/H-Cu/ZnO catalyst obtained through conventional H₂ reduction. The decomposition of precursor and reduction of CuO happened simultaneously during the calcination in N₂, preventing the growth of active Cu⁰ species and aggregation of catalyst particles, which was inevitable during conventional H₂ reduction process. This method is simple and solvent-free, opening a new route to prepare metallic catalysts without further reduction.     

Ce掺杂的蛋壳型CuO/ZnO/SiO2颗粒催化剂的制备和表征

用添加表面活性剂的两步沉淀法制备了以蛋壳型纳米空心SiO2为载体的CuO/ZnO催化剂和掺杂Ce的CuO/ZnO催化剂,初步考察了两组催化剂用于一氧化碳加氢合成甲醇的催化性能,并采用TEM, BET, XRD, XPS等方法对催化剂的结构进行了表征. 结果表明,以纳米空心SiO2为载体的CuO/ZnO催化剂具有较大的比表面积,活性成分在载体表面分散均匀,粒径在13 nm左右. 加入掺杂剂Ce能有效提高催化剂的活性和选择性：一方面,Ce可以降低Cu 2p3/2和Zn 2p3/2的表面结合能, 使氧化铜更容易被氢气还原成铜;另一方面,Ce也能增强铜锌之间的相互作用,抑制铜粒子的烧结,改善活性成分的分散.     

基于生物模板制备二氧化碳加氢反应的Cu/ZnO催化剂

采用油菜花粉作为生物模板制备了具有多层次孔结构的ZnO,再通过浸渍还原法将Cu负载于ZnO上制备了具有不同结构的Cu/ZnO负载型催化剂（bio-CZ-500）,研究发现在500℃条件下焙烧制备的bio-CZ-500催化剂在CO₂加氢反应中经过100 h测试活性几乎不变,同时甲醇选择性高达81%。相比之下,无生物模板制备的Cu/ZnO催化剂显示出较低甲醇选择性（50%）,且催化剂在12 h内快速失活。通过透射电镜、扫描电镜、氮气吸脱附、红外光谱、X射线衍射、X射线光电子能谱、接触角测试、程序升温等表征技术揭示了bio-CZ-500催化剂具有多级孔碳结构、丰富的Cu-ZnO活性界面和较高的水接触角。催化剂的弱亲水性加快了副产物水的扩散,促进了中间体分解制甲醇,同时抑制了铜颗粒的烧结失活,从而提高甲醇的选择性与催化剂的稳定性。该工作为制备高效稳定的Cu基工业催化剂提供了新方法。     

CuO/Al2O3-ZrO2催化剂的制备与表征

以溶胶-凝胶加浸渍法制备了CuO/Al2O3-ZrO2催化剂,对催化剂结构与催化性能进行了表征。结果表明以Al2O3稳定的ZrO2做载体制得的CuO/Al2O3-ZrO2催化剂具有较好的NO转化性能和较低的反应温度。     

催化湿式氧化中负载型催化剂制备

采用浸渍法制备了负载型催化剂CuO/γ-Al_2O_3和Fe_2O_3/γ—Al_2O_3,以甲基橙为代表化合物,考察了制备因素对催化活性的影响,结果表明,CuO/γ-Al_2O_3的活性高于Fe_2O_3/γ-Al_2O_3,催化湿式氧化甲基橙2 h,脱色率接近100%。正交试验和稳定性研究表明,焙烧温度对催化活性影响较大,350℃焙烧,催化剂活性组分Cu溶出较少,且重复使用情况较好。采用SEM和XRD等手段对CuO/γ-Al_2O_3进行表征,发现其活性组分分散度良好。     

负载型γ-Al_2O_3催化剂催化氧化-精馏处理炼油废水

研究了在低温和常压条件下,精馏与催化氧化耦合工艺处理炼油厂废水。以γ-Al_2O_3为载体,Cu、Fe、Mn、Zn、Cd和Ni为主要活性组分,采用浸渍法制备了负载型催化剂,并对其进行XRD表征。利用反应精馏原理,以金属氧化物为催化剂,氧化降解炼油污水,探讨了催化剂的催化寿命与稳定性。结果表明,CuO/γ-Al_2O_3·H_2O_2催化处理炼油废水的COD去除率可达96.2%,催化剂连续使用效果较好。     

负载型铜催化剂的三效催化性能及应用

采用等体积浸渍法制备了以CeO2、Al2O3以及CeO2/Al2O3为载体的负载型CuO催化剂及其老化样品,采用XRD和H2-TPR等技术对老化前后催化剂的结构和氧化还原性能进行了表征。结果显示,对于老化前后的CuO/CeO2/Al2O3催化剂,CuO均能够很好地分散在载体上,即CeO2/Al2O3具有较好的抗烧结能力。考察了不同载体、CeO2和CuO负载质量分数对CuO/CeO2/Al2O3样品三效催化性能的影响,并将制得的CuO/CeO2/Al2O3催化剂与贵金属三效催化剂Pd/CeO2/Al2O3相比较,考察了高温焙烧之后的CuO/CeO2/Al2O3老化样品对CO、C3H6和NO的三效催化性能。结果表明,以10%CeO2/Al2O3为载体,CuO负载质量分数为7%的CuO/CeO2/Al2O3催化剂对汽车尾气脱除催化反应具有较高的催化活性;与Pd/CeO2/Al2O3比较,CuO/CeO2/Al2O3具有更好的低温活性,CO、HC和NOx的起燃温度分别为130℃、250℃和250℃,在350℃三种原料气的转化率均达到90%;老化实验表明,CuO/CeO2/Al2O3具有较好的抗老化性能。