CeO2-TiO2负载型复合光催化剂的制备和性能研究

以玻片为载体，采用溶胶-凝胶法制备了CeO₂-TiO₂复合光催化剂。采用XRD等对催化剂进行了表征。通过可溶性染料酸性媒介红B的微波辅助光催化氧化反应，考察了其光催化活性；并研究了复合催化剂的煅烧温度、铈掺杂量和涂覆次数等对催化活性的影响。实验结果表明，x（CeO₂）＝0.03％，涂覆次数为2次，在400 ℃焙烧2 ｈ的CeO₂-TiO₂负载型光催化剂的活性最高。     

载体和制备方法对铜系一步法合成

以甲醇与乙醇一步反应合成异丁醛反应为基础，研究了不同载体对铜基催化剂反应性能的影 响。分别以SiO₂、SiO_2-ZrO₂、SiO_2-Al₂O₃、Al₂O₃和SiO₂-TiO₂为载体，采用溶胶-凝胶和 浸渍法制备催化剂。采用TPR、XRD和BET等技术对催化剂进行表征。结果表明，复合氧 化物特别是SiO₂-ZrO₂和SiO₂-TiO₂作载体能提高催化剂的比表面积，活性组分分散 好，催化剂的催化性能较好。     

MoP/TiO2-ZrO2催化剂制备及加氢脱氮性能考察

采用溶胶-凝胶法制备了TiO₂-ZrO₂复合载体,并用共浸渍法制备负载型MoP/TiO₂-ZrO₂催化剂,通过原位还原技术对催化剂进行还原处理后,在连续固定床反应器上进行活性评价。结果表明, TiO₂和ZrO₂物质的量比以及Mo负载量对催化剂活性有较大影响,当n(Ti)∶n(Zr)=4∶1和Mo负载质量分数为20%时,MoP/TiO₂-ZrO₂催化剂的加氢脱氮效果最好,并且TiO₂-ZrO₂复合载体比TiO₂-Al₂O₃复合载体的活性提高12.4个百分点。     

工艺条件对Ni/Al2O3和Ni/CeO2-Al2O3催化剂在甲烷自热重整制氢反应中催化性能的影响

采用共沉淀法制备γ-Al₂O₃载体和不同Ce添加量的CeO₂-Al₂O₃载体,然后用浸渍法制备Ni负载质量分数10%的Ni/γ-Al₂O₃和Ni/CeO₂-Al₂O₃催化剂。在固定床微反装置中考察了反应温度、原料气配比和CH₄空速等工艺条件对Ni/γ-Al₂O₃和Ni/Ce₃₀Al₇₀O_δ催化剂在甲烷自热重整制氢反应中催化性能的影响。结果表明,添加Ce的催化剂催化性能有较大提高,在Ni/Ce₃₀Al₇₀O_δ催化剂上,反应温度750 ℃时, CH₄转化率94.3％,与Ni/Al₂O₃催化剂相比,提高20％。Ni/γ-Al₂O₃和Ni/CeO₂-Al₂O₃催化剂的CH₄转化率均随反应温度的升高而增大。原料气中n(O₂)∶n(CH₄)和n(H₂O)∶n(CH₄)的增加均能提高各催化剂的CH₄转化率。但n(O₂)∶n(CH₄)和n(H₂O)∶n(CH₄)的变化对各催化剂的催化性能的影响不同。随着n(O₂)∶n(CH₄)的增大,产物中n（H₂）∶n（CO）降低,n（CO₂）∶n(CO＋CO₂)升高;而n(H₂O)∶n(CH₄)增大时,产物中n（H₂）∶n（CO）和n（CO₂）∶n(CO＋CO₂)均升高。随着CH₄空速的增加,Ni/Al₂O₃催化剂上CH₄转化率、n（H₂）∶n（CO）和n（CO₂）∶n(CO＋CO₂)均较大程度下降;而在Ni/Ce₃₀Al₇₀O_δ催化剂上,随着CH₄空速的增加,CH₄转化率、n（H₂）∶n（CO）和n(CO₂）∶n(CO＋CO₂)变化不大。     

新型储氧、储氮材料——Ba掺杂的CeO2-ZrO2固溶体

利用“超声膜扩散法”制备了系列Ba掺杂的CeO₂-ZrO₂固溶体,研究了Ba掺杂对CeO₂-ZrO₂固溶体的热稳定性和储放氧能力的影响,并测量了Ba掺杂CeO₂-ZrO₂固溶体材料的储存NOx性能。结果表明,随着Ba含量的增加,固溶体的储氧量先增加后降低,在Ce_0.5Zr_0.5O₂·xaO系列固溶体中,当x=0.16时,样品储氧量达到最大,新鲜样品的储氧量可达到745 μmol·g^-1,样品的NO储量随含Ba量的增加而线性增加。     

CeO2的制备及其在催化剂载体中的应用研究进展

概述了 CeO₂的制备方法对其性能的影响以及CeO2在催化剂载体中的运用,指出 CeO₂独特的储放氧性能使其在氧化反应、甲醇裂解、重整及变换反应和氮氧化物的还原等反应过程中呈现了良好的载体功能;溶胶-凝胶法以及超临界干燥等方法可以制备大比表面积的载体 CeO₂。制约载体 CeO₂工业应用的因素在于其机械强度和耐热性。     

铜锰氧化物水煤气变换催化剂的还原与催化性能

以CuSO₄·5H₂O和MnSO₄·H₂O为前驱物,NaOH为沉淀剂,选用共沉淀工艺,添加Al₂O₃、BaO+Al₂O₃、ZrO₂+Al₂O₃或CeO₂+Al₂O₃粉末作为催化助剂,制备了4种铜锰氧化物水煤气高温变换催化剂。X射线衍射分析表明,4种铜锰氧化物催化剂的主要化学成分为氧化铜和氧化锰系化合物以及锰钡、铜锰和铜锰铝复合氧化物;在催化水煤气变换反应(WGSR)后,4种铜锰氧化物的化学成分发生了变化。H2还原实验结果表明,在4种铜锰氧化物中,添加ZrO₂+Al₂O₃的铜锰氧化物H₂还原效率最好;而添加CeO₂+Al₂O₃的铜锰氧化物H2还原效率最小。对WGSR出口气中CO体积分数进行对比分析可知,分别添加Al₂O₃和CeO₂+Al₂O₃铜锰氧化物催化剂的变换活性较好。     

Cu1Zr1Ce9Oδ催化剂选择性氧化CO性能的研究

用共沉淀法制备了Cu₁Zr₁Ce₉O_δ催化剂,考察了反应温度和反应气体中各组分对Cu₁Zr₁Ce₉O_δ催化剂上选择性氧化CO反应的影响。结果表明,降温的过程中Cu₁Zr₁Ce₉O_δ催化剂的活性滞后。H₂的存在有利于CO的脱附,促进了低温下选择性氧化CO的反应;而温度较高时,H₂氧化副反应的发生降低了CO的转化率,反应气中H₂O和CO₂降低了催化剂的活性和选择性,最佳反应温度为（160~200） ℃,O₂的进入量取3为宜。     

铁含量对Fe-Mn-K催化剂上CO2加氢反应性能的影响

在370 ℃、2.0 MPa和600 h^－1条件下，考察了Fe-Mn-K复合催化剂上的CO₂选择性加氢合成低碳烯烃性能。XRD表征表明，复合催化剂中负载的金属组分主要以Fe₂O₃和MnO₂形式存在。通过H₂-TPR和CO₂-TPD研究了Fe-Mn-K催化剂对H₂的还原性能和CO₂吸附性能的影响，当催化剂中Fe负载质量分数为12%时，H₂-TPD温度较低，CO₂转化率大于30%，C⁼₂～C⁼₄低碳烯烃选择性也较高。CO₂-TPD结果表明，随Fe含量的增加，初始脱附温度提高，脱附量增加，催化剂对CO₂的吸附强度逐渐增大。     

MoO3改性SO42-/Al2O3-ZrO2固体酸的制备和表征

以硝酸锆为锆源、硝酸铝为铝源,采用共沉淀法制备了Al₂O₃-ZrO₂复合载体,通过MoO₃改性和H₂SO₄浸渍法制备了MoO₃改性的SO₄^2-/Al₂O₃-ZrO₂催化剂。用XRD和FT-IR对催化剂进行表征,用元素分析仪测定硫含量,用乙酸和正丁醇的酯化反应对其催化活性进行考察。结果发现,当MoO₃添加质量分数达12.0%时,出现MoO₃衍射峰,表明适当的MoO₃可以单层分布在催化剂表面,从而稳定SO₄^2-的存在。FT-IR分析结果表明,催化剂具有固体酸的特征峰。在MoO₃添加质量分数为8.0%和焙烧温度650 ℃时,催化剂的催化活性达最大值,催化活性与硫含量的增加不一致。     

载体对Au-Pd催化剂甲醇部分氧化制氢性能的影响

用PVP保护乙醇还原法制备了一系列Au-Pd/MOx(M=Zn、Ce、Fe、Ti、Cr和Al)双金属催化剂,考察了不同载体对Au-Pd催化剂甲醇部分氧化制氢性能的影响,用XRD、TG、TPD、TPR和TPH等对催化剂进行了表征。结果表明,载体对催化剂性能有较大影响,与钛、铬和铝氧化物载体相比,448K时偏碱性的锌、铈和铁氧化物载体负载的Au-Pd催化剂的甲醇转化率均在80.0%以上,催化剂积碳量降低。其中以Au-Pd/ZnO催化剂的效果最好,523K时甲醇转化率和氢气选择性分别为99.0%和45.6%,反应20h后积碳量仅为0.0232g/gcat.。     

MoP/SiO_2-TiO2-ZrO_2催化剂加氢脱硫工艺条件考察

采用共沉淀法制备了SiO_2-TiO_2-ZrO_2三元复合氧化物载体,用浸渍法负载活性组分MoP制备MoP/SiO_2-TiO_2-ZrO_2催化剂。在固定床微反应器上,采用正交实验研究了反应温度、空速、氢油体积比和氢分压对催化剂噻吩加氢脱硫性能的影响,并对劣质催化裂化(FCC)柴油的脱硫性能进行了考察。结果表明,催化剂最佳加氢脱硫条件为:反应温度380℃,空速2 h^(-1),氢油体积比500,氢分压4 MPa,此条件下,FCC柴油脱硫率达97.50%。     

纳米CeO_2载体对Au-Pd催化剂性能的影响

采用十六胺和不同铈前驱体(硝酸铈铵或硝酸亚铈)分别合成了纳米CeO2(H4和H3),考察了纳米CeO2载体的织构性质对Au-Pd催化剂甲醇部分氧化制氢(POM)性能的影响,用HRTEM、N2吸附、XRD和TPR等对样品进行了表征。结果表明,铈前驱体对载体的性能有较大的影响,以硝酸铈铵为前驱体所制H4载体具有较小的粒径(约5 nm)和平均孔径(5.3 nm)、较大的比表面积(243 m2/g),而硝酸亚铈所制H3载体具有较大的平均孔径(7.9 nm)。POM结果表明,纳米CeO2负载的Au-Pd催化剂具有较好的催化性能,300℃时,Au-Pd/H3的活性和H2选择性分别达100%和59.7%。低温时催化剂的活性和H2选择性为:Au-Pd/H3>Au-Pd/H4,而高温时顺序相反,这是由于低温时催化剂的孔径对反应物和产物的扩散影响较大,高温时催化剂的比表面积和活性组分分散度起主要作用。     

Ag/CeO2-ZnO催化剂上甲醇部分氧化制氢气研究

研究了用于甲醇部分氧化制氢气反应的Ag/CeO2-ZnO催化剂的制备条件以及反应条件对催化剂性能的影响.Ag/CeO2-ZnO催化剂中银含量、焙烧温度、反应温度以及反应气的比例等对催化剂性能具有很大的影响.Ag/CeO2-ZnO催化剂的制备条件以及反应条件控制在一定范围内时,Ag/CeO2-ZnO催化剂对甲醇部分氧化制氢气具有很高的催化活性与选择性.     

溶胶凝胶法制备SiO_2-TiO_2-ZrO_2加氢脱芳催化剂载体

首次采用溶胶-凝胶法制备不同物质的量比的SiO2-TiO2-ZrO2复合氧化物,并采用吡啶吸附红外光谱法、N2物理吸附和X射线衍射法对其进行表征。以复合氧化物为载体制备了MoP/SiO2-TiO2-ZrO2,在微型固定床反应器上以萘的十二烷溶液为模型化合物,在360℃、压力3.0 MPa、空速2h-1、氢油体积比500的反应条件下,考察了该催化剂的加氢脱芳性能。结果表明,载体的酸性与n(Si)∶n(Ti)∶n(Zr)有关,L酸量显著影响脱芳效果;载体中TiO2锐钛矿晶形明显,峰型尖锐,且具有较大的孔容、孔径。通过表征和活性评价结果选出最佳的n(Si)∶n(Ti)∶n(Zr)=0.163∶0.809∶0.029,其萘的稳定转化率为90%。     

Ignition of methanol partial oxidation over supported platinum catalyst

Supported platinum catalysts were prepared by precipitation of H₂PtCl₆ on powders of different metal oxides. Catalytic activity of the prepared catalysts was tested with reaction of partial oxidation of methanol (POM) for hydrogen production. Most of the prepared catalysts can ignite POM at the ambient temperature. The conversion of methanol and the selectivity of hydrogen and carbon monoxide, however, increased with the reaction temperature and varied with the kind of support and platinum loading. A 1 wt% Pt/ZnO catalyst exhibited optimized methanol conversion and selectivity at a low reaction temperature of 150 °C. The reactor may reach this temperature within 2 min after a start of the exothermic reaction.     

A Comparative Study of Partial Oxidation of Methanol over Zinc Oxide Supported Metallic Catalysts

Au/ZnO, Pd/ZnO and Au–Pd/ZnO catalysts were prepared by PVP-stabilized reduction method by C₂H₅OH. The catalysts have been used successfully for hydrogen production by partial oxidation of methanol (POM). The influence of Au, Pd and Au–Pd on the performance of supported catalysts for POM has been investigated. The prepared samples were characterized by ICP, XRD, BET, TPR and TPD. The results show that the Au–Pd/ZnO catalyst are more active and exhibit higher hydrogen selectively compared to the Pd/ZnO and Au/ZnO catalyst, the methanol conversion of 99.5% and hydrogen selectivity of 65.6% were obtained at 573 K. The enhanced activity and stability of the bimetallic Au–Pd/ZnO catalyst has been explained in terms of the higher dispersion and basic density, smaller particles of gold and synergetic effect between gold and palladium.     

Methanol partial oxidation on carbon-supported Pt and Pd catalysts

Different Pt and Pd catalysts supported on an activated carbon were prepared by using different metal precursors. Prepared catalysts were pretreated at 400 °C under different atmospheres to decompose the precursor compound and reduce the metal. After pretreatments, the supported catalysts were characterized by H₂ chemisorption, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy to know their metal dispersion, particle size, distribution and oxidation state. Afterwards, the catalysts were tested in methanol partial oxidation with two different O₂/CH₃OH molar ratios. Results obtained in this reaction were compared with those obtained for methanol decomposition in inert atmosphere. For Pt catalysts, there was an increase in methanol conversion and hydrogen production and a decrease in carbon monoxide production under oxidizing conditions. Both methanol conversion and partial oxidation reactions appear to be sensitive to Pt particle structure in the particle size range studied. Results obtained under oxidizing conditions differed between Pd and Pt catalysts. Finally, catalytic activity in methanol partial oxidation was more affected by Pt than Pd particle size in the size range studied.     

Production of hydrogen via partial oxidation of methanol over Au/TiO2 catalysts

Selective production of hydrogen by partial oxidation of methanol (CH₃OH + (1/2)O₂ → 2H₂ + CO₂) over Au/TiO₂ catalysts, prepared by a deposition–precipitation method, was studied. The catalysts were characterized by XRD, TEM, and XPS analyses. TEM observations show that the Au/TiO₂ catalysts exhibit hemispherical gold particles, which are strongly attached to the metal oxide support at their flat planes. The size of the gold particles decreases from 3.5 to 1.9 nm during preparation of the catalysts with the rise in pH from 6 to 9 and increases from 2.9 to 4.3 nm with the rise in calcination temperature up to 673 K. XPS analyses demonstrate that in uncalcined catalysts gold existed in three different states: i.e., metallic gold (Au⁰), non-metallic gold (Au^δ+) and Au₂O₃, and in catalysts calcined at 573 K only in metallic state. The catalytic activity is strongly dependent on the gold particle size. The catalyst precipitated at pH 8 and uncalcined catalysts show the highest activity for hydrogen generation. The partial pressure of oxygen plays an important role in determining the product distribution. There is no carbon monoxide detected when the O₂/CH₃OH molar ratio in the feed is 0.3. Both hydrogen selectivity and methanol conversion increase with increasing the reaction temperature. The reaction pathway is suggested to consist of consecutive methanol combustion, partial oxidation and steam reforming.     

壳-核式RuO2-TiO2/CeO2-TiO2复合催化剂的制备及催化湿式氧化性能研究

以CeO2-TiO2为载体,通过化学沉积、纳米活性层包覆、纳米烧结的方法在其表面包覆了RuO2/TiO2纳米层,制备得壳-核式RuO2-TiO2/CeO2-TiO2复合催化剂。通过XRD、XPS、UV-Vis、BET、SEM、TEM等手段对催化剂进行了表征。结果表明:纳米层中的RuO2包覆在TiO2表面,也形成了一种壳-核式结构,TiO2粒子的粒径约15nm,其表面的RuO2厚度约4nm,包覆纳米层后催化剂的比表面积明显增大。以丁二酸为模拟废水,对催化剂的催化湿式氧化活性进行了测试,研究了反应温度、pH等因素对催化湿式氧化活性的影响。与浸渍法制备的催化剂相比,新催化剂催化湿式氧化丁二酸的活性显著提高。乙酸和丙烯酸是丁二酸降解的主要中间产物。