掺磷非晶氧化钛负载铂用于高效催化氧化挥发性有机化合物（英文）

高活性催化剂是挥发性有机化合物(VOCs)催化氧化消除的关键因素。本研究通过简单的共沉淀法成功制备了具有高比表面积的非晶介孔磷掺杂氧化钛负载铂催化剂(Pt/ATO-P)。通过P掺杂,既可获得非晶介孔结构,又可获得高ATO-P比表面积(可达278.9m~2·g~(-1))。非晶介孔Pt/ATO-P催化剂显示出优异的VOCs催化氧化性能和良好的热稳定性。Pt/ATO-P样品在空速为36000m L·h~(-1)·g~(-1)、甲苯浓度为10000m L·m~(-3)的反应条件下,对甲苯催化氧化的T_(50)和T_(90)(实现50%和90%转化率所需的温度)分别为130℃和140℃,明显优于无磷催化剂Pt/TiO_2。这些发现可以为拓展非晶介孔磷化材料在环境净化和能源转化等领域的应用提供重要参考。     

锶磁性固体酸S2O82-/ZrO2SrFe12O19催化剂的制备和表征

以具有优异磁学特性的锶铁氧体(SrFe₁₂O₁₉)粒子为磁性基体, 负载固体酸制备锶磁性固体酸催化剂S₂O₈^2-/ZrO₂-SrFe₁₂O₁₉。利用XRD、 比表面积测试(BET)、 振动样品磁强计(VSM)、 IR等表征手段, 研究了磁性催化剂的表面性质和催化性能。结果表明: SrFe₁₂O₁₉的掺入提高了介稳的四方晶型t-ZrO₂的热稳定性; 固体酸的磁性能较好, 饱和磁化强度(M_s)在30.0 emu·g^-1左右, 矫顽力(H_c)大于3900 G, 有利于磁分离和重复使用; BET表面积为16.0 m²·g^-1, 平均孔径为8.16 nm, 属于介孔磁性材料; 以乌桕油与甲醇的酯交换为探针反应的研究表明, 该固体酸能在较短时间内有效发挥催化作用。     

焙烧温度对Cu-Mn/γ-Al2O3催化剂催化氧化甲苯性能的影响

采用浸渍法合成了Cu-Mn/γ-Al₂O₃催化剂, 通过XRD、BET、H₂-TPR和XPS等方法对经不同温度(300~600℃)焙烧的催化剂进行表征, 采用固定床管式反应装置考察了焙烧温度对催化剂催化氧化甲苯的影响, 并讨论活性组分、表面Cu⁺/(Cu⁺+Cu²⁺)和Mn⁴⁺/(Mn⁴⁺+Mn³⁺)摩尔比值与催化剂活性的关系。结果发现, 550℃焙烧温度的催化剂活性最好, 氧化能力最强, 其转化率为95%时对应的反应温度T₉₅(286 ℃)最低, CO₂的选择性达100%。在550℃焙烧时生成的Cu_1.4Mn_1.6O₄新相以及催化剂表面中相对含量更高的Cu⁺和Mn⁴⁺是催化剂具有高活性的主要原因。     

大比表面三维介孔MCM-48分子筛负载Pt催化氧化甲苯

采用自合成大比表面三维有序介孔分子筛MCM-48(≈1400 m²/g)为载体，其上负载Pt,获得负载型Pt/MCM-48,应用于甲苯催化燃烧，与微孔分子筛Silicalite-2、介孔分子筛材料SBA-15和MCM-41以及商用SiO₂等硅基载体相比，展示出优异的低温催化氧化性能。在此基础上，考察不同Pt负载量对负载型Pt/MCM-48催化燃烧甲苯性能的影响，筛选出的1%(质量分数)理论负载量的催化剂具备最佳催化氧化性能。对等体积浸渍法、原位合成法、甲醇法、乙二醇法等不同引入方式的考察发现，等体积浸渍法与原位合成法向载体上引入Pt的实际负载量接近于理论添加量，相比之下，甲醇法、乙二醇法等溶剂法获得Pt实际负载量远低于理论负载量。转化频率(turnover frequency, TOF)计算结果表明，甲醇法获得的Pt/MCM-48中Pt转化效率以及Pt原子利用率最高。BET,XPS,STEM以及H₂-TPR等表征充分证明，MCM-48超大的比表面为Pt的分散提供了有利条件，有助于获得高比例Pt⁰;有...     

有机-无机氧化硅空心球的合成及VOCs吸附应用

介孔有机-无机复合氧化硅空心球(MOSs)在碱性条件下以反向胶束为模板经过正硅酸乙酯(TEOS)和1,2-双(三乙氧基甲硅烷基)乙烷(BTSE)共缩合被成功合成, 并通过不同手段对样品的结构和性能进行表征。MOSs用于去除挥发性有机物(VOCs), 研究其对水蒸气、正己烷、甲苯和92#汽油的静态吸附性能, 并以商业硅胶(SG)和活性炭(AC)为参考。实验结果发现, 初始BTSE/(BTSE+TEOS) 摩尔比为10%时, (MOS-10%)的样品具有均匀的中空介观结构和最大的VOCs吸附容量(1.28 g·g^-1正己烷, 1.25 g·g^-1甲苯和1.14 g·g^-1 92#汽油), 静态水蒸气吸附量最小(0.630 g·g^-1)。通过穿透曲线评估单一组分VOC(正己烷或甲苯)在MOS-10%上的动态吸附行为, 动态正己烷和甲苯吸附结果以及高湿度条件下的正己烷吸附性能表明, 与商业吸附剂相比, MOS-10%具有最佳的穿透时间、吸附能力和疏水性。对于二元组分同时吸附(正己烷和甲苯), MOS-10%的正己烷吸附性能优于甲苯。介孔有机-无机复合氧化硅空心球的动态VOCs吸附容量较大归因于有机基团、表面积和孔体积的共同作用。MOSs的VOCs去除能力强和可回收性优良, 显示出巨大的VOCs捕获潜力。     

Pd负载型介孔ZrO2-TiO2复合材料的设计合成及其CO催化氧化性能研究

以介孔结构的复合ZrO₂-TiO₂为载体负载活性组分, 制备了具有高CO催化氧化活性的Pd/ZrO₂-TiO₂与PdCu/ZrO₂-TiO₂负载型催化剂。XRD、TEM研究结果表明: 活性组分Pd、Cu物种可均匀分散于介孔载体中。系统考察了不同的催化剂载体、制备方法和助催化剂等对该介孔复合材料CO催化氧化性能的影响, 结果表明: 以ZrO₂-TiO₂为载体的催化剂其CO催化氧化活性明显优于以介孔Al₂O₃或介孔SBA-15为载体的催化剂; 一步法制备的介孔Pd/ZrO₂-TiO₂催化剂其CO催化氧化的低温活性较浸渍法制备的Pd/ZrO₂-TiO₂有很大提高; 并且Pd和Cu物种共负载的介孔ZrO₂-TiO₂复合催化剂具有最优的CO催化氧化活性, 其CO的完全催化氧化温度可降至170℃, O₂-TPD分析说明Pd和Cu之间的相互作用使得PdCu/ZT催化剂在更低温度具有氧化还原活性。     

尖晶石型AFe2O4催化剂的制备及其催化燃烧甲苯的研究

通过溶胶-凝胶-自蔓延燃烧法制备尖晶石型AFe₂O₄(A=Cu, Co, Ni, Mg, Zn)催化剂, 以甲苯为VOCs模拟气, 考察AFe₂O₄催化剂对VOCs的催化燃烧活性, 并采用XRD、N₂吸附-脱附、SEM、TEM、H₂-TPR、XPS对催化剂进行表征分析。结果表明: AFe₂O₄表现出较好的催化燃烧活性, 其中CuFe₂O₄的催化燃烧活性最佳, 起燃温度(T50)和完全燃烧温度(T90)分别为188℃、239℃。AFe₂O₄具有明显的片状尖晶石晶体, 并形成以介孔为主的多级孔结构, 该特点为催化剂提供了大量表面活性位。A位元素种类对其催化燃烧活性影响较大, 当A位元素为Cu时, Cu的H₂还原峰面积远大于其他元素, H₂还原温度仅为289℃, 表面亲电子氧和氧空位浓度占氧元素总量(O_ele/O_1S)的36%。CuFe₂O₄为片状反尖晶石晶型, 晶格体积仅为0.294 nm³, 并伴有CuO和α-Fe₂O₃物种。以介孔为主的多级孔结构、特有的片状反尖晶石晶型以及该晶型与CuO和α-Fe₂O₃的协同作用是CuFe₂O₄催化燃烧活性提高的主要原因。     

石墨烯基介孔锰铈氧化物催化剂:制备和低温催化还原NO

锰铈氧化物由于较强的氧化还原活性、优良的低温脱硝性能,已被广泛用于选择性催化还原(SCR)脱硝反应,但是锰铈氧化物存在活性组分易团聚、比表面积较低等问题,限制其催化剂活性的提高。本研究以介孔结构的石墨烯基SiO₂(G@SiO₂)纳米材料为模板,采用水热法制备了系列石墨烯基介孔锰铈氧化物(G@MnO_x-CeO₂)催化剂,并考察了该催化剂在低温下(100～300℃)的SCR脱硝性能。结果表明,与石墨烯基铈氧化物(G@CeO₂)相比,G@MnO_x-CeO₂催化剂具有较高脱硝活性。当Mn、Ce与模板G@SiO₂质量比分别为0.35、0.90时, G@Mn(0.35)Ce(0.9)催化剂的脱硝活性最佳, 220℃下NO转化率达到最高(80%)。添加适量MnO_x,提高了G@MnO_x-CeO₂催化剂的比表面积、孔容,降低了催化剂的结晶度;并且MnO_x<...     

鸟巢状CuCeZrOx三元复合氧化物的合成及其对碳烟颗粒的催化氧化性能研

采用尿素均相沉淀法合成了CuCeZrO_x(CCZ)三元复合氧化物催化剂。采用X射线衍射分析(XRD)、N₂-吸脱附测试、X射线光电子能谱(XPS)、扫描透射电镜(STEM)、程序升温还原(脱附、氧化)等技术, 考察煅烧温度对催化剂的物化性质和催化碳烟燃烧活性的影响。结果表明: 350℃煅烧产物CCZ-350表现出最优的催化活性: 在空速为12000 mL/(g_catalyst·h), O₂浓度为10vol%, NO浓度为500×10^-6, 催化剂和碳烟以10︰1质量比松散接触条件下, 碳烟颗粒最大燃烧速率温度T₅₀ = 407℃, 同时表现出极佳的抗水汽中毒和抗SO₂中毒性能, 这与活性组分的高度分散以及催化剂表面大量高活性吸附氧物种的存在有关。此外, 催化剂材料具有疏松多孔的鸟巢状结构, 有利于催化剂和碳烟颗粒的充分接触。该催化剂在柴油车尾气排放温度范围内(150~400℃)还能完全催化氧化柴油车尾气中CO、C₃H₆和C₃H₈等其他污染物, 显示出优异的催化净化柴油车尾气的综合性能。     

三维有序介孔结构氧化钼制备及催化性能

以三维有序介孔分子筛KIT-6为模板剂制备碳模板, 七钼酸铵为钼源, 采用超声辅助下的真空浸渍法, 合成了三维(3D)有序介孔、蠕虫状介孔MoO₃。采用TEM、HRTEM、SAED、XRD、TG/DT、N₂吸脱附等对材料物理性能进行了表征。采用H₂-TPR、甲苯和一氧化碳完全氧化等对催化性能进行了评价。研究发现: 制备的三维有序介孔MoO₃为正交相晶体结构, 比表面积194 m²/g; 在转化率分别为50%、90%、100%时, 甲苯的起燃温度分别为203℃、215℃、225℃; CO起燃温度分别为114℃、158℃、180℃。3D-MoO₃优良的催化性能与高比表面和三维有序介孔架构密切相关。     

催化剂MnCe（y）Ox/TiO2的制备及其催化燃烧甲苯的活性

以TiO2为载体,采用浸渍法制备了不同配比的MnCe复合型催化剂,并采用X射线衍射(XRD)、氧气的程序升温脱附(O2-TPD)和氢气的程序升温还原(H2-TPR)对制备的催化剂进行表征,比较了催化剂催化氧化(燃烧)甲苯的活性。研究结果表明,所制备的催化剂MnCe(y)Ox/TiO2对甲苯有明显的催化活性。当Ce/(Mn+Ce)的摩尔比为0.1时,催化剂MnCe(0.1)Ox/TiO2的催化活性最高,甲苯的转化率达到90%时的温度为254℃。在催化剂MnOx/TiO2中掺杂少量的Ce元素,有利于活性组分Mn物种在载体表面上以更小颗粒而且更高的分散度存在,从而提高催化剂的催化活性。     

Catalytic performance of nanosized Pt-Au alloy catalyst in oxidation of methanol and toluene

The alloy formed between a group-VII metal such as platinum and a group-IB metal such as gold changes the catalytic behavior compared to the monometallic phase, increasing the selectivity toward certain products and also decreasing the deactivation rate. Pt-Au alloy nanoparticles coated on alumina support were found to be catalytically very active for complete oxidation of methanol and toluene. Furthermore, the nanosized Pt-Au particles were added to ZnO/Al2O3 on monolith catalyst. Also, effect of various parameters such as concentration of methanol and toluene and feed flow rate was investigated. Au particles were sized in 20 approximately 30 nm and Pt particles were well dispersed. In case of alumina supported powder catalyst, complete oxidation of methanol occurred at a temperature lower than that of toluene. From oxidation activity of monolithic honeycomb with Pt and Au particles, the conversion of methanol was increased with increasing the concentration of methanol, but conversion of toluene showed a decreasing tendency as the concentration of toluene increased. Also, conversion of methanol over honeycomb catalyst was not largely affected by feed flow rate, while conversion in toluene oxidation was decreased rapidly as feed flow rate was increased. As a result, the Pt-Au/ZnO/Al2O3/M catalyst used is likely to efficiently treat a large volume of exhaust gas containing VOCs.     

炭气凝胶负载Pt基催化剂的制备及其甲醇氧化催化性能

以间苯二酚(R)和甲醛(F)为原料,制备R-F炭气凝胶(RF-CAs).继以后者为载体采用浸渍还原法制备铂基催化剂Pt/CA,并比较其与由相同负载工艺制得的以Vulcan XC-72为载体的铂基催化剂Pt/XC72的催化甲醇氧化反应的性能.结果表明,前者具明显高的甲醇氧化催化活性,显示CAs是一种极具潜在竞争力的燃料电池催化剂载体材料.     

Aged nano-structured platinum based catalyst: effect of chemical treatment on adsorption and catalytic activity

To examine the effect of chemical treatment on the adsorption and catalytic activity of nanostructured platinum based catalyst, the aged commercial Pt/AC catalyst was pretreated with sulfuric acid (H2SO4) and a cleaning agent (Hexane). Several reliable methods such as nitrogen adsorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and inductively coupled plasma (ICP) were employed to characterize the aged Pt/AC catalyst and its chemically pretreated Pt/AC catalysts. The catalytic and adsorption activities of nano-structured heterogeneous Pt/AC catalyst were investigated on the basis of toluene oxidation and adsorption isotherm data. In addition, the adsorption isotherms of toluene were used to calculate the adsorption energy distribution functions for the parent catalyst and its pre-treated nano-structured Pt/AC catalysts. It was found that sulfuric acid aqueous treatment can enhance the catalytic performance of aged Pt/AC catalyst toward catalytic oxidation of toluene. It was also shown that a comparative analysis of the energy distribution functions for nano-structured Pt/AC catalysts as well as the pore size distribution provides valuable information about their structural and energetic heterogeneity.     

Catalytic oxidation of dichloromethane and toluene over platinum alumite catalyst

Catalytic oxidation technology is one of the most promising technologies for the reduction of volatile organic compound (VOC) emissions. It is very necessary to study the catalytic oxidation of mixture of VOCs and volatile organic compounds (CVOCs), because VOCs are always emitted accompanying with CVOCs. Hence, the catalytic oxidation reaction of toluene and CH2Cl2 is explored on a platinum alumite catalyst in this work. The results show that the addition of toluene has no effect on the decomposition of CH2Cl2, although it can suppress CH3Cl formation because the steam generated from the catalytic combustion of toluene suppresses the formation of CH3Cl from CH2Cl2. High concentrations of CH2Cl2 have a negative effect on the catalytic combustion of toluene.     

不同载体Mn-Ce催化剂的制备及其脱硝性能

以TiO_2、SiO_2及Al_2O_3为载体,采用分步共混法制备了三种均质整体式Mn-Ce负载型催化剂,探究了不同载体对催化剂脱硝活性、N2选择性及机械强度的影响。结果表明,以TiO_2和SiO_2为载体的催化剂80℃的脱硝率接近90%,而以Al2O3为载体的催化剂仅达46%。催化剂的表征发现这与Mn-Ce/TiO2和Mn-Ce/SiO2催化剂的比表面积和表面酸量较Mn-Ce/Al2O3更大、更多有关。而三种催化剂的N2选择性在80~200℃之间均接近100%,然而Mn-Ce/SiO2催化剂200℃以上N2选择性比其余两种催化剂差。三种催化剂的机械强度为Mn-Ce/TiO2Mn-Ce/SiO2Mn-Ce/Al2O3,其微观形貌显示这与催化剂体相结构的密实状况有关,各催化剂的活性组分氧化物均以无定形态存在。     

Pt/C doped TiO2/SWNTs as catalyst for methanol oxidation

Platinum/carbon doped titanium dioxide/single-walled carbon nanotubes (Pt/C/TiO2/SWNTs) were successfully prepared by blending method. These composite catalysts were found to exhibit an anatase TiO2 structure with uniform Pt/C and the existence of SWNTs can be confirmed by transmission electron microscopy (TEM). The composite of Pt/C with TiO2/SWNTs could improve an enhancement in catalytic properties upon applying TiO2/SWNTs as catalyst support. The catalytic oxidation of methanol of Pt/C doped TiO2/SWNTs is found to be higher as compared to the undoped and Pt/C doped materials.     

Study on the Phase Transformation Behavior of Nanosized Amorphous TiO2

Nanosized amorphous TiO2 powders with a specific surface area of 501 m^2.g^-1 were prepared by hydrolysis. After calcined at 400℃ for 2 h, the prepared amorphous TiO2 powders were fully transformed into anatase crystallites with a specific surface area of 141 m^2.g^-1. Differential scanning calorimetric (DSC) experiments were performed on the samples of nanosized amorphous TiO2 mixed with microsized anatase, nanosized anatase, or nanosized α-Al2O3 respectively. Effects of sample packing, anatase addition, or α-Al2O3 addition on the crystallization behavior of nanosized amorphous TiO2 were analyzed.