Cu/Mn/Ce三元氧化物催化剂对甲苯催化燃烧性能的研究

采用浸渍法制备了不同Cu/Mn/Ce摩尔比的铜锰铈三元复合氧化物催化剂。通过XRD、和H_2-TPR对催化剂的晶相结构和晶格氧的移动性进行了表征和分析,采用常压气-固反应装置考察了不同的铜锰铈摩尔比对催化氧化甲苯性能的影响,并讨论了催化剂晶相组成、氧移动性与催化活性的关系。结果显示,铜锰氧化物复合形成的新相Cu1.4Mn1.6O4是具有更高催化活性的中心,Ce O_2的加入提高了Cu_(1.4)Mn_(1.6)O_4分散度,从而增强了催化剂的氧移动性,提高了催化剂的活性和氧化能力。当Cu/Mn/Ce摩尔比为1:1:4时,催化氧化甲苯的活性最佳,T95%为282.6℃,CO_2选择性为100%。     

La_(0.75)K_(0.25)Mn_(0.95)Cu_(0.05)O_3/CeO_2催化净化FCC再生烟气的研究

采用浸渍法制备La_(0.75)K_(0.25)Mn_(0.95)Cu_(0.05)O_3/CeO_2钙钛矿型复合氧化物催化剂(负载质量分数分别为10%、20%、30%、50%和100%),利用XRD、FT-IR及UV-Vis DRS表征手段对制备的催化剂进行表征,以C_2H_2为还原剂,考察该氧化催化剂净化FCC再生烟气的性能。结果表明,制备的系列氧化催化剂存在明显的钙钛矿结构,并且La_(0.75)K_(0.25)Mn_(0.95)Cu_(0.05)O_3/CeO_2(50%)催化剂的氧化活性最高。     

尖晶石型Mn_(1-x)M_xCo_2O_4柴油车尾气处理催化剂的制备及其应用

尖晶石型复合氧化物因具有独特的结构特征而成为相对理想的柴油车尾气处理催化剂。采用溶胶-凝胶法制备尖晶石型Mn_(1-x)M_xCo_2O_4催化剂,通过X射线衍射(XRD)和程序升温氧化(TDO)等对Mn_(1-x)M_xCo_2O_4催化剂进行表征。结果表明,制备的样品Mn_(1-x)M_xCo_2O_4均为尖晶石型复合氧化物;掺杂Cu、Ce后,催化剂的氧化性能有不同程度的变化。在固定床微型反应器上对催化剂催化活性进行评价,结果表明,与纯MnCo_2O_4相比,Mn_(0.9)Ce_(0.1)Co_2O_4催化剂催化活性提高,Mn_(0.9)Cu_(0.1)Co_2O_4催化剂催化活性降低,但CO_2选择性增加。     

Y~(3+)掺杂NiFe_2O_4尖晶石对乙醇水蒸气重整制氢性能的影响

以NaOH为沉淀剂,采用共沉淀法制备NiFe_(2-y)Y_yO_4系列催化剂。在固定床反应器上进行催化剂在乙醇水蒸气重整反应中的活性评价。通过X射线粉末衍射(XRD)和程序升温还原(TPR)对催化剂的晶体结构、还原特性进行表征。结果表明,掺杂的钇离子可以进入尖晶石的晶格当中,形成y≤0.1的NiFe_(2-y)Y_yO_4物种,掺杂钇的尖晶石物种比NiFe_2O_4的晶格常数大;当y0.1时,多余的Y_2O_3可与NiO反应生成NiYO_3物种;掺杂钇的尖晶石物种在高温还原性气氛中可部分还原为FeYO_3物种和Ni单质。NiFe_(1.9)Y_(0.1)O_4催化剂在乙醇水蒸气重整反应中表现出良好的催化性能,450℃时乙醇转化率接近100%,在600℃时甲烷的物质量分数低至2.34%,氢气的质量分数为75.85%。在反应进程中未发现失活、积碳和烧结等现象,催化剂稳定性良好。     

稀土固体超强酸SO_4~(2-)/TiO_2/La~(3+)催化合成马来酸二丁酯

以固体超强酸SO4 2 -/TiO2 /La3 + 为催化剂 ,马来酸和正丁醇为原料合成马来酸二丁酯 ,考察了影响反应的因素。结果表明 :n (醇 )∶n (酸 ) =4 0∶1 ;催化剂用量为 1 0g (马来酸为 0 1mol的情况下 ) ;带水剂甲苯为 1 5mL ;反应时间为 3 0h是最适宜的反应条件 ,酯化率达 97 4 %。     

Bi—Sr—Ca—Cu—O系超导相形成过程中的中间相

研究确认,在Bi-Sr-Ca-Cu-O系统固相反应中,T_c为85K的Bi_2Sr_2Ca_1Cu_2O_(8+δ)超导相(即2212相)是经由一个Bi-Sr-Ca-O四元中间相与CuO等反应生成的。应用DTA、XRD、SEM等手段详细研究了此中间相形成条件及其成分和晶体结构。确定该中间相系组成为BiSryCa_(1-y)O_(2.5)的Bi-Ca-O和Bi-Sr-O固溶体(式中y=0-0.75)。y=0时的结构属单斜晶系,其a=23.083A、b=5.409A、c=21.132A,β=110.688°。y值增大,其结构不变,d值有规律地稍有增加。但当y>0.5后,晶体结构畸变加剧,中间相成分及Sr固溶量对超导相形成及其结构和性能有重要影响;对确定单相性好的高品质高温超导体合理制备工艺有重要意义。     

逆уCeO2/CuχCo1-χOδ催化剂的制备 及其CO催化氧化性能

以Cu(NO_3)_2·3H_2O、Co(NO_3)_2·6H_2O、Ce(NO_3)_3·6H_2O和(NH_4)_2CO_3为原料,采用共沉淀法-浸渍法结合的制备方式,制得逆负载型уCe O_2/Cu_χCo_(1–χ)O_δ催化剂(у=0、5%、15%、25%;χ=0～1.0;δ=1.0～1.4)。通过XRD、BET、H_2-TPR、XPS考察了Cu O和Co_3O_4质量比[m(Cu O)∶m(Co_3O_4)]、表面Ce O_2负载量(у)(以Cu_χCo_(1–χ)O_δ质量为基准,下同)对逆负载уCe O_2/Cu_χCo_(1–χ)O_δ催化剂催化氧化CO性能的影响。结果表明,15%Ce O_2/Cu_(0.2)Co_(0.8)O_δ[m(Cu O)∶m(Co_3O_4)=0.2∶0.8]催化剂催化性能最佳。常压下,当反应温度为75℃时,CO转化率可达100%。由于15%Ce O_2/Cu_(0.2)Co_(0.8)O_δ比表面积较大,两相界面较多,进而使得Ce O_2与Cu—O—Co固溶体相互作用较强,表面存在较多的氧空穴、Cu~+和Co~(3+),催化剂还原温度较低,催化活性较好。     

(1-y)Ca1-xLa2x/3TiO3-yCa(Mg1/3Nb2/3)O3复合微波介质陶瓷的研究

采用固相合成法制备了 ( 1-y)Ca1 -xLa2x/ 3 TiO3 -yCa(Mg1 / 3 Nb2 / 3 )O3 系列微波介质陶瓷材料 ,研究了复合系统的微波介电性能、烧结性能和微观结构。研究结果表明 :在y =0 .4～ 0 .6范围内 ,体系形成了单一的钙钛矿结构 ;当复合体系组成 0 .5Ca0 .6La0 .2 67TiO3 -0 .5Ca(Mg1 / 3 Nb2 / 3 )O3 时 ,在 14 0 0℃下烧结保温 4小时所得到材料的微波介电性能最佳 ;εf=5 5 ,Q×f =45 0 0 0GHz( 7.6GHz下 ) ,τf=0 .0 4ppm/℃。     

一种山梨醇脱水制备异山梨醇的方法

<正>一种山梨醇脱水制备异山梨醇的方法,一种以不溶性杂多酸盐A_xH_(3-x)PW_(12)O_(40),A_xH_(3-x)PMo_(12)O_(40),A_yH_(4-y)SiW_(12)O_(40), A_yH_(4-y)SiMo_(12)O_(40)为催化剂催化山梨醇制备异山梨醇的方法,其中,A=Ag~+,Cs~+,NH4~+,Rb~+,K~+;x=1～2.5;y=1～3;该方法在无溶剂、减压的条件下进行,反应温度为120℃～200℃,反应时间为     

甘蔗渣纤维素磷酸酯的合成与应用研究

甘蔗渣纤维素为原料 ,用尿素作催化剂 ,研究了甘蔗渣纤维素磷酸酯合成的最佳工艺条件。将 5 .0g甘蔗渣纤维素与w(NaOH) =2 0 %的 3 0mL水溶液反应 1h ,水洗至中性 ,制得碱纤维 ,5 .0g碱纤维再用w (H3PO4) =2 0 %的水溶液 4 0mL进行预膨润 12h ,将滤饼用 5mLw(H3PO4) =85 %的水溶液、0 .3g催化剂尿素、甲苯作溶剂 ,5 0℃下反应 1h。产品对Ag+、Pb2 +、Fe3+、Zn2 +离子的平衡交换吸附量比活性炭平均增加 7.15mg/g ,对X -GRRL阳离子蓝染料的交换吸附性能比活性炭提高了 15 .7%。     

负载型CuMnO_x/TiO_2催化剂催化燃烧甲苯

采用沉积-沉淀法制备CuMnO_x/TiO_2新型甲苯燃烧催化剂,考察焙烧温度、Cu与Mn物质的量比、Cu和Mn总负载量、空速及水蒸汽含量对催化甲苯燃烧性能的影响。研究表明,焙烧温度500℃和Cu与Mn物质的量比为1∶1时,催化剂活性最好,反应温度250℃时,甲苯去除率为100%;水蒸汽的出现明显降低了甲苯转化率。XRD和H2-TPR表征结果表明,CuMnO_x/TiO_2催化剂的主要活性相为铜锰尖晶石(Cu1.5Mn1.5O4),它的存在降低了CuMnO_x/TiO_2催化剂的还原温度,是催化活性优良的主要原因。     

Total oxidation of ethanol and propane over Mn-Cu mixed oxide catalysts

Mn-Cu mixed oxides were prepared by co-precipitation varying the aging time for 4, 18 and 24 h. The catalytic performance in propane and ethanol total oxidation on these samples was better than on Mn₂O₃ and CuO pure oxides. The increase of the aging time enhanced the activity and the selectivity to CO₂. The nature and disposition of the phases forming the catalytic system as well as the effect of the precipitated aging time was determined by means of specific surface area measurements, X-ray diffractometry (XRD), infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (TPR) and temperature programmed desorption of oxygen (O₂-TPD). The catalytic behaviour seems related to the existence of a Cu_1.5Mn_1.5O₄ mixed phase and the easier reducibility of the catalysts.     

Facile synthesis of spinel LiNi0.5Mn1.5O4 as 5.0 V-class high-voltage cathode materials for Li-ion batteries

LiNi_0.5Mn_1.5O₄ and LiMn₂O₄ with novel spinel morphology were synthesized by a hydrothermal and post-calcination process. The synthesized LiMn₂O₄ particles (5-10 μm) are uniform hexahedron, while the LiNi_0.5Mn_1.5O₄ has spindle-like morphology with the long axis 10-15 μm, short axis 5-8 μm. Both LiMn₂O₄ and LiNi_0.5Mn_1.5O₄ show high capacity when used as cathode materials for Li-ion batteries. In the voltage range of 2.5-5.5 V at room temperature, the LiNi_0.5Mn_1.5O₄ has a high discharge capacity of 135.04 mA·h·g^-1 at 20 mA·g^-1, which is close to 147 mA·h·g^-1 (theoretical capacity of LiNi_0.5Mn_1.5O₄). The discharge capacity of LiMn₂O₄ is 131.08 mA·h·g^-1 at 20 mA·g^-1. Moreover, the LiNi_0.5Mn_1.5O₄ shows a higher capacity retention (76%) compared to that of LiMn₂O₄ (61%) after 50 cycles. The morphology and structure of LiMn₂O₄ and LiNi_0.5Mn_1.5O₄ are well kept even after cycling as demonstrated by SEM and XRD on cycled LiMn₂O₄ and LiNi_0.5Mn_1.5O₄ electrodes.     

The roles of Cu, Zn and Mn in Cu0.5Zn0.5Mn2O4 spinel-lattice catalyst for methanol decomposition

Cu_0.5Zn_0.5Mn₂O₄ spinel-lattice catalyst has been studied for methanol decomposition by in situ infrared (IR) spectroscopy analysis and micro reactor study. Methoxy species is formed by dissociative adsorption of methanol which subsequently converts into formate species via step-wise dehydrogenation process. The activities of surface intermediates on reduced CuO, ZnO and Mn₂O₃ catalysts are strongly affected by the ease of hydrogen desorption from the site, the strength of C–H bonding and the availability of oxygen. A synergism between Cu and MnO whereby the Cu serves as a sink for reverse hydrogen atoms spillover from MnO has been proposed. The micro reactor analysis correlates well with the IR results.     

PAN-H1.6Mn1.6O4锂离子筛膜的制备及在卤水中吸附性能

采用亲水的PAN为成膜材料,制备了掺杂H_1.6Mn_1.6O₄的PAN-H_1.6Mn_1.6O₄锂离子筛膜。通过SEM、Li⁺静态吸附实验、（NH₄）₂S₂O₈对锂的洗脱实验和卤水中吸附实验,研究了锂离子筛的添加量对PAN-H_1.6Mn_1.6O₄锂离子筛膜结构、Li⁺吸附-洗脱性能的影响。结果表明,PAN浓度为10%（质量）,H_1.6Mn_1.6O₄的添加量为50%（质量）时,PAN-H_1.6Mn_1.6O₄离子筛膜的吸附量为17.45 mg·g^-1,达到粉末状吸附量的88.0%。以（NH₄）₂S₂O₈为洗脱剂,当浓度为0.3 mol·L^-1、液固比为600:1、时间为12 h时,锂洗脱量为17.23 mg·g^-1,锰溶损率仅为1.14%。在含有Na⁺、K⁺、Mg²⁺和Ca²⁺的罗布泊老卤卤水中,锂离子筛膜对Li⁺有很高的选择性。在卤水中进行10次吸附与解吸循环,吸附量从11.64 mg·g^-1下降到10.94 mg·g^-1,吸附容量仅损失6.0%。总体结果表明亲水性载体对H_1.6Mn_1.6O₄吸附容量影响较小,温和的洗脱剂对锂离子筛膜的化学稳定性有利。     

Selective hydrogenation of cinnamaldehyde over Raney cobalt catalysts modified with salts of heteropolyacids

The hydrogenation of cinnamaldehyde to cinnamyl alcohol was carried out over Raney cobalt catalysts modified by Cu_3/2PMo₁₂O₄₀. It was found that the conversion of cinnamaldehyde decreases substantially with increases in the amount of Cu_3/2PMo₁₂O₄₀ deposited on Raney cobalt catalysts. The maximum yield of cinnamyl alcohol varies with the amount of deposited Cu_3/2PMo₁₂O₄₀. The more the deposited modifier, the higher the attainable maximum yield of cinnamyl alcohol. With 2.8% Cu_3/2PMo₁₂O₄₀ modified Raney cobalt, the selectivity for cinnamyl alcohol does not change with reaction temperature and reaction time. Thus, it is likely that the selectivity of ca. 80% for cinnamyl alcohol represents a specific value which is related to the nature of the surface modifier, Cu_3/2PMo₁₂O₄₀. The influences of the heteropolyanions and the competitive cations on the conversion and the selectivity were also investigated. It was found that copper salts of different heteropolyacids acting as the modifier of the catalyst bring about different enhancements in the selectivity for cinnamyl alcohol. The order of enhancement of selectivity in terms of heteropolyacid anion is PMo₁₂O³⁻₄₀>SiMo₁₂O⁴⁻₄₀>PW₁₂O³⁻₄₀. There is little difference in selectivity by modification with (NH₄)₆Mo₇O₂₄ and Cu₂SiMo₁₂O₄₀. Raney cobalt catalyst modified by different 12-molybdophosphate containing cations of alkali, alkaline earth and transition metals gives a similar selectivity of about 75%. Among all of the 12-molybdophosphates, that containing the cation Cu²⁺ is the best in improving the selectivity of the catalysts. A selectivity as high as 83% was attained when an amount of 2.8% Cu_3/2PMo₁₂O₄₀ was deposited on the catalyst.     

Cu-based spinel catalysts CuB2O4 (B = Fe, Mn, Cr, Ga, Al, Fe0.75Mn0.25) for steam reforming of dimethyl ether

Cu-based spinel-oxides CuB₂O₄ (B = Fe, Mn, Cr, Ga, Al, or Fe_0.75Mn_0.25) were synthesized via a sol–gel method and subsequent solid-state reaction. The spinels mechanically mixed with γ-Al₂O₃ were evaluated for production of hydrogen from dimethyl ether steam reforming (DME SR). The reduction behavior and crystal property of these spinel-oxides, and the Cu oxidation state in spinel catalysts were investigated by temperature-programmed reduction, X-ray diffraction, and X-ray photoelectron spectroscopy techniques. The reduced phases of the Cu-based spinel catalysts that strongly affected the catalytic activity and durability were composed of metallic copper with metal oxides (MnO (B = Mn), Cr₂O₃ (B = Cr), and Al₂O₃ (B = Al)) or with spinels (CuGa₂O₄ (B = Ga), Fe₃O₄ (B = Fe), and MnFe₂O₄ (B = Fe_0.75Mn_0.25). The stability of B metal oxides and the interaction between copper species and B metal oxides significantly contributed to the reforming performance.     

火焰喷雾合成法制备La0.8Sr0.2Mn1-xCuxO3催化氧化CO性能研究

采用火焰喷雾合成法制备了Sr²⁺、Cu²⁺分别取代A、B位的La_0.8Sr_0.2Mn_1-xCu_xO₃ （x=0,0.1,0.2,0.3,0.4）钙钛矿催化剂,并用于CO催化氧化实验,研究了水蒸气和CO₂对催化剂CO氧化活性的影响。对不同取代量La_0.8Sr_0.2Mn_1-xCu_xO₃ 催化剂进行了XRD、SEM、EDS、BET、XPS、H₂-TPR和O₂-TPD等表征测试。结果表明,火焰喷雾合成法制备的钙钛矿催化剂具有良好的钙钛矿相、疏松多孔结构和催化氧化活性。其中,La_0.8Sr_0.2Mn_0.9Cu_0.1O₃分别在119.4℃和133.3℃实现50%和90%的CO转化率。掺杂水蒸气和CO₂会与CO在催化剂表面形成竞争吸附,导致5种催化剂性能衰减,但La_0.8Sr_0.2Mn_0.9Cu_0.1O₃仍能在150.2℃实现90%的CO催化转化,在连续稳定性催化氧化测试中,5种催化剂性能衰减不超过10%。结合上述CO催化氧化实验,火焰喷雾合成法制备的催化剂具有良好的稳定性和催化活性,适合制备高CO催化氧化活性的钙钛矿催化剂。     

Accurate low-pressure kinetics for isobutane oxidation over phosphomolybdic acid and copper(II) phosphomolybdates

A low-pressure steady-state technique has been used to investigate the rates and mechanisms of the oxidation of isobutane over H₃[PMo₁₂O₄₀], CuH₄[PMo₁₂O₄₀]₂, Cu₂H₂[PMo₁₂O₄₀]₂, Cu_2.5H[PMo₁₂O₄₀]₂, and Cu₃[PMo₁₂O₄₀]₂. Observed oxidation products over all catalysts are methacrolein, 3-methyl-2-oxetanone, acetic acid, carbon dioxide and water. The most selective catalyst for methacrolein formation at low temperatures (<496 °C) is Cu_2.5H[PMo₁₂O₄₀]₂, where both Cu(II) reduction and acid sites play a role. The least active catalyst at low temperatures is phosphomolybdic acid followed by Cu₃[PMo₁₂O₄₀]₂. This activity is reversed at higher temperatures. The 3-methyl-2-oxetanone is a unique product and is likely to be the precursor to methacrylic acid. Acetic acid is also probably a precursor to complete oxidation. Catalyst deactivation or restructuring is significant only over H₃[PMo₁₂O₄₀].     

Oxidative dehydrodimerization of methane on Bi-Mn oxides: Catalyst active component and reaction mechanism

A series of Bi-Mn-O catalysts has been studied as a function of bismuth content (from 0 to 100 atom.%). The fresh-prepared samples are found to be a heterophasic mixture of the Bi₂Mn₄O₁₀ compound with the individual manganese or bismuth oxide, the surface of which is enriched in bismuth. At initial period of catalytic work, a part of Bi₂Mn₄O₁₀ decomposes to ga-Bi₂O₃ and -Mn₂O₃ resulting in the formation of rather effective catalyst for methane oxidative coupling. It is postulated that the catalyst active component consists of a Bi₂O₃ phase lying at the surface of a Bi₂Mn₄O₁₀ compound. At a steady state, the oxidative dehydrodimerization reaction occurs via both redox and associative mechanisms whilst the deep oxidation proceeds mainly according to the redox one.