Pd/γ-Al2O3-TiO2催化剂上乙醇乙醛的催化氧化性能研究

采用混胶法和机械混合等方法制备了Pd质量分数为1%的Pd/γ-Al₂O₃-TiO₂催化剂,并对其催化活性、影响条件进行了考察。结果说明,由混胶法制备的Pd/γ-Al₂O₃-TiO₂催化剂对乙醇和乙醛的完全氧化表现出优异的催化性能,其活性明显高于单一载体催化剂Pd/TiO₂和Pd/Al₂O₃,150℃时乙醇和乙醛的转化率分别达到98.9%和98.5%。在较宽温度范围内和高空速条件下表现出良好的稳定性。同时运用XRD、TEM和FT-IR等技术对催化剂进行了表征。结果表明,在Pd/γ-Al₂O₃-TiO₂催化剂中Al₂O₃与TiO₂之间存在着较强的相互作用,使γ-Al₂O₃-TiO₂的比表面积和孔容积均调变到一个适中的数值,同时在催化剂表面Al₂O₃参与形成了有利于其催化活性的表面结构。     

络合浸渍法制备Ag/Al2O3-TiO2催化剂及其催化燃烧丙烷性能

研究了制备过程中不同络合剂乙醇胺（ETA）、二乙醇胺（DTA）、三乙醇胺（TEA）及柠檬酸（CA）等对Ag/Al₂O₃-TiO₂催化剂理化性质的影响,并考察了其催化丙烷燃烧的活性。结果表明,络合浸渍法能够显著提高催化剂催化活性,其活性顺序依次为：Ag/Al₂O₃-TiO₂(IM,传统浸渍法) < Ag/Al₂O₃-TiO₂(TEA) < Ag/Al₂O₃-TiO₂(DTA) < Ag/Al₂O₃-TiO₂(ETA) < Ag/Al₂O₃-TiO₂(CA),表明CA作为络合剂效果最好。当CA与Ag的物质的量比为1:1时,催化剂的催化活性最佳。与Ag/Al-Ti(IM)催化剂相比,Ag/Al₂O₃-TiO₂催化剂的T₉₀（丙烷转化率为90%的反应温度）下降了81 ℃。由催化剂的结构分析发现,络合浸渍法制备的催化剂银物种的粒径明显变小、银的分散度提高、表面Ag⁰物种和表面吸附氧的含量增加,进而促进了丙烷催化燃烧性能的提升。      

Pd@SiO2/Al2O3的制备及其催化氧化CO性能评价

从Pd纳米粒子出发制备具有核壳结构的Pd@SiO₂纳米粒子,并将其负载于不同形貌Al₂O₃载体上,制备出具有良好CO催化氧化活性的催化剂。以纳米球形Al₂O₃为载体时,Pd@SiO₂/Al₂O₃催化剂活性优于无核壳结构的Pd/Al₂O₃催化剂。将纳米Pd@SiO₂负载到球形和菱形Al₂O₃上,制备出Pd@SiO₂/Al₂O₃催化剂。结果表明:具有较大比表面积的Al₂O₃载体(球形)有利于Pd@SiO₂的分散,且SiO₂层可以抑制Pd粒子的团聚,能在一定程度上改善催化活性。而较小比表面积的载体(菱形)上出现了Pd@SiO₂的团聚,表现出较低的CO氧化活性,但在降低负载量后,CO氧化活性明显提高。该结果为推动新型热稳定、高效纳米三效催化剂的研发具有一定的启示意义。     

V2O5-Sb2O3-TiO2催化剂 低温NH3还原NO及其抗H2O和SO2毒化性能

浸渍法制备了催化剂V₂O₅-Sb₂O₃-TiO₂,考察了V₂O₅、Sb₂O₃负载量、pH值和焙烧温度对催化剂V₂O₅- Sb₂O₃-TiO₂低温氨选择性催化还原(SCR)NO活性的影响;同时,考察了催化剂V₂O₅-Sb₂O₃-TiO₂抗H₂O和SO₂毒化性能。结果表明,V₂O₅和Sb₂O₃负载量分别为5%和2%、焙烧温度为400℃、pH值为4时,催化剂SCR活性最好,反应温度220℃时,可达97%。Sb₂O₃的加入不仅能增强V₂O₅/TiO₂的催化活性,而且能明显提高催化剂的抗H₂O和SO₂毒化性能。SO₂、NO吸附暂态反应和TG-DTG测试表明,Sb₂O₃的促进机制主要是促进了催化剂在SO₂存在条件下对NO的吸附,同时,减弱了硫酸铵盐与催化剂之间的相互作用,硫酸铵盐更容易分解。     

助剂对Co/Al2O3催化剂浆态床费托合成反应性能影响

考察了ZrO₂、Ru或Pt助剂对Co/Al₂O₃催化剂结构及浆态床费托合成反应性能的影响。实验结果表明,添加ZrO₂助剂可阻止或降低难还原铝酸钴的形成、促进催化剂的还原、提高Co/Al₂O₃催化剂对费托合成反应的催化活性、降低甲烷选择性并提高C₅₊烃选择性。H₂-TPR表征结果表明,少量Ru或Pt助剂均能降低Co-ZrO₂/Al₂O₃催化剂中钴物种还原温度(Co₃O₄→CoO和CoO→Co⁰),提高催化剂的还原度,催化剂呈现出良好的CO加氢反应活性。此外,催化剂组分间浸渍次序对费托合成反应性能有重要影响,载体γ-Al₂O₃先浸渍Zr组分,可有效抑制难还原化合物形成;Co、Ru组分共浸渍加强了Co和Ru组分密切接触程度,更利于钴物种的还原;Co、Pt组分依次浸渍更利于活性组分的均匀分布,催化剂具有最佳的费托合成反应性能。     

Al2O3改性CuO/Fe2O3催化剂水煤气变换反应性能

采用分步共沉淀法制备了不同Al₂O₃含量(0%-15% (w))的CuO/Fe₂O₃催化剂, 并进行水煤气变换反应(WGSR)评价测试. 制得的催化剂中含有复合物CuFe₂O₄, 其晶粒尺寸, 氧化还原性质和表面Cu分散通过相应表征手段加以研究. X 射线粉末衍射(XRD), 拉曼(Raman)光谱, N₂物理吸附, N₂O分解和CO₂程序升温脱附(CO₂-TPD)等表征技术说明适量Al₂O₃的加入可以促进尖晶石CuFe₂O₄发生由四方相向立方相的转变, 阻止催化剂中Cu烧结, 增大表面Cu分散, 增加弱碱性位点的数量. 此外, 采用H₂程序升温还原(H₂-TPR)技术探究改性的CuO/Fe₂O₃催化剂的还原性能. 关联结果发现, Al₂O₃掺杂在增大铜物种的耗氢量, 降低其还原温度方面起着重要的作用. 即Al₂O₃的添加促进CuO/Fe₂O₃催化剂中铜铁物种之间的协同作用. 结合活性测试和表征结果,适量的Al₂O₃ (10%(w))改性的催化剂具有较小的Cu颗粒尺寸、较大的Cu分散、较强的还原性能、较多数量的弱碱性位点, 因此具有更好的初始活性和热稳定性.     

Pt/Al2O3和Pt/CeO2/Al2O3催化甲烷部分氧化制合成气反应

研究了Pt/Al₂O₃和Pt/CeO₂/Al₂O₃对甲烷部分氧化制合成气反应的催化活性,发现Pt/CeO₂/Al₂O₃显示了更高的甲烷转化率和合成气选择性.用H₂-TPR、H₂-TPD、SEM-EDX和XRD等技术对催化剂进行了表征.CeO₂和Pt相互作用促进Pt在催化剂表面的分散,抑制Pt在催化剂表面的迁移;降低了催化剂的燃烧活性,提高了催化剂的部分氧化活性和选择性,可避免因催化剂床层局部温度过高而导致催化剂活性下降或失活,提高了催化剂的稳定性.同时,CeO₂通过促进水汽变换反应使反应体系迅速达到平衡,提高了催化剂对H₂的选择性.     

耐硫甲烷化中H2S浓度对MoO3/Al2O3和CoO-MoO3/Al2O3催化剂的影响

在0 到12 mL·L^-1 (体积分数φ=0.00%-1.20%) 范围内考察了不同H₂S 浓度对25% (质量分数, w)MoO₃/Al₂O₃和5% (w) CoO-25%MoO₃/Al₂O₃催化剂甲烷化性能的影响. 结果表明, 5%CoO-25%MoO₃/Al₂O₃的甲烷化活性随H₂S浓度的增加单调上升, 而25%MoO₃/Al₂O₃对H₂S浓度并不敏感. 对比这两种催化剂发现, 只有在H₂S浓度高于0.40% (φ) 时, 在25%MoO₃/Al₂O₃中添加Co助剂才会有促进作用; H₂S浓度低于0.40% (φ)时, Co助剂会抑制25%MoO₃/Al₂O₃催化剂的甲烷化活性. 分别对反应前后的催化剂表征发现, H₂S浓度的改变不会对两种催化剂的物理结构产生明显的影响, 而是通过影响催化剂表面的金属硫化物活性位来影响催化剂的甲烷化性能. 耐硫甲烷化反应体系中较高的硫含量下Co助剂才表现出对25%MoO₃/Al₂O₃催化剂的促进作用. 该研究明确了在MoO₃/Al₂O₃催化剂中添加Co助剂的硫化氢浓度范围, 为工业上选择合适的催化剂提供了依据.     

甲醇水蒸气重整制氢的高效碳纳米管改性Cu/ZnO/Al2O3催化剂

以碳纳米管为助剂,制备用于甲醇水蒸气重整制氢的新型高效Cu/ZnO/Al₂O₃催化剂,并与传统Cu/ZnO/Al₂O₃催化剂在相同条件下的催化性能进行了比较.结果表明,添加适量碳纳米管可显著提高催化剂的低温催化活性和选择性,在大幅度提高产氢速率的同时有效降低了重整产气中CO的含量.SEM和XRD分析证实适量碳纳米管的添加有效促进了Cu/ZnO/Al₂O₃催化剂结构特性的改善,有利于活性铜物种的分散,从而显著提高了催化剂的低温催化性能.     

Ru-Ni/Al2O3催化马来酸二甲酯加氢性能研究

以Al₂O₃为载体,RuCl₃·xH₂O及Ni（NO₃）₂·6H₂O为活性组分前驱体,采用吸附-沉淀法制备系列Ru-Ni/Al₂O₃催化剂,以马来酸二甲酯（DMS）催化加氢为探针反应,考察了活化条件和Ni的添加量对催化剂性能的影响。随Ni负载量的升高,Ru-Ni/Al₂O₃催化剂活性呈现先升高后降低的趋势,在Ni：Ru的原子比为6：1时（催化剂Ru₁Ni₆/Al）催化活性最高。催化剂Ru₁Ni₆/Al在氢气中200 ℃直接还原后的平均转化率与氢气中400 ℃还原后的平均转化率接近,达到了单组分Ru/Al催化剂的1.5倍以上。XPS、XRD、H₂-TPR数据表明,Ru与Ni之间发生了较强的相互作用,Ni的加入促进了金属Ru在载体上的分散,提高了催化活性。     

Simultaneous removal of ethanol, acetaldehyde and nitrogen oxides over V-Pd/γ-Al_2O_3-TiO_2 catalyst

V-Pd/γ-Al2O3-TiO2 catalysts with different vanadium contents were prepared by a combined sol-gel and impregnation method. X-ray diffraction (XRD), N2 adsorption-desorption (BET), X-ray photoelectron spectroscopy (XPS) and catalytic removal of ethanol, acetaldehyde and nitrogen oxides at low temperature (<300 ?C) were used to assess the properties of the catalysts. The results showed that the sample with 1wt% vanadium exhibited an excellent catalytic performance for simultaneous removal of ethanol, acetaldehyde and nitrogen oxides. The conversions of ethanol, acetaldehyde and nitrogen oxides at 250 ?C were 100%, 74.4% and 98.7%, respectively. V-Pd/γ-Al2O3-TiO2 catalyst with 1 wt% vanadium showed the largest surface area and higher dispersion of vanadium oxide on the catalyst surface, and possessed a larger mole fraction of V4+ species and unique PdO species on the surface, which can be attributed to the strong synergistic effect among palladium, vanadium and the carriers. The higher activity of V-Pd/γ-Al2O3-TiO2 catalyst is related to the V4+ and Pd2+ species on the surface, which might be favorable for the formation of active sites.     

氧化还原预处理对一氧化碳低温氧化Pd/CeO2-TiO2催化剂性能的影响

研究了氧化还原预处理对溶胶-凝胶法制备的CeO2-TiO2复合氧化物负载Pd催化剂上CO低温氧化性能的影响，并对催化剂的稳定性进行了考察。H2-TPR结果表明，83 ℃的耗氢峰是PdO和载体中CeO2共同还原的结果，高温还原后Pd与载体之间相互作用加强。经高温氧化(500 ℃)低温还原(150 ℃)预处理的催化剂CO低温氧化活性最好，在反应气组成为0.5% CO＋1.6% O2＋6.0%N2＋Ar，空速为30 000 mL·g－1·h－1，程序升温反应显示CO完全转化温度为48 ℃，这种预处理方式能够形成适宜的载体与金属间相互作用。稳定性实验在室温下进行，反应气组成为0.6% CO＋14.7% O2+55.3％N2＋Ar，Pd/CeO2-TiO2催化剂具有较好的低温反应稳定性，100%CO转化率可持续12 h。     

Ethanol steam reforming over Ni-Cu/Al2O3-MyOz （M = Si, La, Mg, and Zn） catalysts

Ni-based catalysts doped with copper additives were studied on their role in ethanol steam reforming reaction.The effects of Ca content,support species involving Al2O3-SiO2,Al2O3-MgO,Al2O3-ZnO,and Al2O3-La2O3,on the catalytic performance were studied.Characterizations by TPR,XRD,NH3-TPD,XPS,and TGA indicated that catalysts 30Ni5Cu/Al2O3-MgO and 30NiSCu/Al2O3-ZnO have much higher H2 selectivity than 30NiSCu/Al2O3-SiO2,as well as good coke resistance.H2 selectivity for 30Ni5Cu/Al2O3-MgO catalyst was 73.3% at 450℃ and increased to 94.0% at 600 ℃,whereas for 30NiSCu/Al2O3-ZnO catalyst,the H2 selectivity was 63.6% at 450 ℃ and 95.2% at 600 ℃.These Al2O3-MgO and Al2O3-ZnO supported Ni-Cu bimetallic catalysts may have important applications in the production of hydrogen by ethanol steam reforming reactions.     

Pd/MoO3-TiO2/SiO2光催化CO2与C2H6合成烃类氧化物的反应性能

 采用化学反应改性和等体积浸渍法制备了负载型Pd/MoO3-TiO2/SiO2催化剂,并用IR,FT-Raman,TPD-MS,UV-Vis DRS和活性评价等方法研究了催化剂的表面结构、光吸收性能、化学吸附性能及光催化CO2与C2H6合成烃类氧化物的反应性能. 结果表明,SiO2负载的MoO3和TiO2之间存在着强相互作用,并能部分形成Mo-O-Ti键联,使得两种氧化物微粒均匀分布于载体表面; 表面MoO3和TiO2的复合作用使TiO2/SiO2的吸光带边红移,扩展了其吸光域,Pd的引入明显提高了固体材料的可见光吸收率; CO2和C2H6能较好地吸附在催化剂表面,在紫外光的激发下,CO2吸附态能解离生成CO,而C2H6单位吸附态能部分转化为C和H同时吸附在两个晶格氧上的双位吸附态; 光促CO2和C2H6反应主要生成丙醛、乙醇和乙醛; 在合适的条件下,烃类氧化物的选择性可超过90%.     

以ZrO2-TiO2为载体的整体式锰基催化剂应用于低温NH3-SCR反应

以MnO2为活性组分,Fe2O3为助剂,制备了以TiO2及ZrO2-TiO2为载体的整体式催化剂.考察了它们在不同温度焙烧后应用于富氧条件下,NH3选择性催化还原.(NH3-SCR)氮氧化物的低温反应性能和高温稳定性.用X射线衍射(XRD)实验、比表面积测定(BET)、储氧性能测定(OSC)及程序升温还原(H2-TPR)等方法对催化剂进行了表征.结果表明,以ZrO2-TiO2为载体的催化剂具有很好的高温热稳定性,并具有较高的比表面积和储氧能力.同时具有较强的氧化能力.催化剂的活性测试结果表明,以ZrO2-TiO2为载体的整体式锰基催化剂明显地提高了NH3-SCR反应的低温活性,具有良好的应用前景.     

Gas Phase Selective Catalytic Oxidation of Toluene to Benzaldehyde on V2O5-Ag2O／η-Al2O3 Catalyst

Gas phase selective catalytic oxidation of toluene to benzaldehyde was studied on V2O5-Ag2O/η-Al2O3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM,and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No.4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzalde hydewere higher than those on the undoped catalyst. This was attributed to the disordered structure of V2O5 lattice of the K-doped catalyst and a better interfacial contact between the particles.     

以ZrO2-TiO2为载体的整体式锰基催化剂应用于低温NH3-SCR反应

以MnO2为活性组分, Fe2O3为助剂, 制备了以TiO2及ZrO2-TiO2为载体的整体式催化剂. 考察了它们在不同温度焙烧后应用于富氧条件下, NH3选择性催化还原(NH3-SCR)氮氧化物的低温反应性能和高温稳定性. 用X射线衍射(XRD)实验、比表面积测定(BET)、储氧性能测定(OSC)及程序升温还原(H2-TPR)等方法对催化剂进行了表征. 结果表明, 以ZrO2-TiO2为载体的催化剂具有很好的高温热稳定性, 并具有较高的比表面积和储氧能力, 同时具有较强的氧化能力. 催化剂的活性测试结果表明, 以ZrO2-TiO2为载体的整体式锰基催化剂明显地提高了NH3-SCR反应的低温活性, 具有良好的应用前景.     

Gas Phase Selective Catalytic Oxidation of Toluene to Benzaldehyde on V2O5-Ag2O/η-Al2O3 Catalyst

Gas phase selective catalytic oxidation of toluene to benzaldehyde was studied on V2O5-Ag2O/η-Al2O3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM,and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No.4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzaldehyde were higher than those on the undoped catalyst. This was attributed to the disordered structure of V2O5 lattice of the K-doped catalyst and a better interfacial contact between the particles.