Ce-Zr-O2上CuO分散性对CO氧化活性的影响

采用柠檬酸法制备了Ce-Zr-O₂固溶体, 并负载了过渡金属和贵金属Pt, 其中, 以Cu作为活性组分, 在CO氧化反应中表现出最高的活性, CO完全转化的温度约为120 ℃, 明显高于负载1%Pt(质量分数)催化剂的活性. 掺杂少量Zr到CeO₂(Ce_0.8Zr_0.2O₂)中对Cu基催化剂有非常好的促进作用. 分别采用等体积浸渍法(IW)、 沉淀沉积法(DP)、 水热法(HT)以及柠檬酸法(CA)制备了Cu负载质量分数为20%的Cu/Ce_0.8Zr_0.2O₂催化剂. 结果表明, 由沉淀沉积法制备的Cu/Ce_0.8Zr_0.2O₂催化剂的活性最高, 在100 ℃时, CO可完全转化. TEM结果表明, CuO物种很好地分散在Ce_0.8Zr_0.2O₂上. 吸附实验数据表明, Cu基催化剂上CO与O₂之间较弱的竞争吸附是其活性高于Pt催化剂的主要原因. Cu基催化剂上的氧空位对促进O₂的吸附具有重要作用, 也是影响CO低温氧化的重要因素之一.     

M/ZSM-5(M=Cu、Mn、Fe、Ce、Ti)催化氧化甲苯性能研究

以ZSM-5分子筛为载体，采用浸渍法负载Cu、Mn、Fe、Ce、Ti制备一系列金属氧化物催化剂，利用SEM、XRD、N₂吸附-脱附、XPS、H₂-TPR对催化剂的理化性质进行了表征，并考察了催化剂的催化氧化甲苯性能。结果表明，Cu/ZSM-5表面粗糙，金属元素分布均匀，具有较好的孔径结构、良好的低温还原性和丰富的吸附氧物种，且负载量为5%的Cu/ZSM-5表现出优异的甲苯催化活性和最佳的抗硫性，在SO₂环境下t₉₀为224℃(GHSV=24000 h^-1)。原位红外测试结果表明，甲苯的降解遵循以下途径，甲苯首先被吸附在催化剂表面形成吸附态甲苯，随后在催化剂作用下依次被转化为苯甲醛和苯甲酸，再经过开环反应形成马来酸、羧酸等小分子有机物，最终被氧化为CO₂和H₂O。     

Cu、Mn、Ce改性V2O5-WO3/TiO2/堇青石催化剂Urea-SCR脱除NO

采用硅胶为黏结剂,在堇青石蜂窝陶瓷上以涂覆法依次负载Cu、Mn、Ce改性的纳米TiO₂粉末、W改性的V₂O₅粉末得到复合催化剂,在120～550 ℃用尿素选择性催化还原(Urea-SCR)氮氧化物时显示良好活性。与商业催化剂V₂O₅-WO₃/TiO₂相比,添加Cu、Mn、Ce后,催化剂脱硝活性显著提高,活性温度窗口明显拓宽。结果表明,催化剂的高活性与催化剂表面适度的酸碱性、高比值的V⁴⁺/V⁵⁺以及良好的氧化还原性能和锐钛矿相的TiO₂、丰富的表面裂纹的存在等因素有关。     

柠檬酸量对水热合成CuO/Ce0.8Zr0.2O2催化水气变换制氢性能的影响

采用水热法合成了Ce_0.8Zr_0.2O₂固溶体,再经浸渍法负载活性组分制备了CuO/Ce_0.8Zr_0.2O₂催化剂,考察了柠檬酸量对Cu O/Ce_0.8Zr_0.2O₂催化剂结构、性质及其催化水气变换反应制氢性能的影响。结果表明,不同柠檬酸量制备的CuO/Ce_0.8Zr_0.2O₂催化剂的催化活性主要与Cu比表面积、还原性能及Ce_0.8Zr_0.2O₂固溶体与Cu O之间的相互作用有关。其中,柠檬酸浓度为0.04 mol/L所制备的催化剂具有较大的Cu比表面积,较低的Cu O还原温度和较强的Ce_0.8Zr_0.2O₂固溶体与CuO之间的相互作用,在水气变换制氢过程中具有较高的CO转化率,表现出了较好的催化...     

Cu-V-O氧化物催化燃烧甲苯的活性和抗硫性

采用溶胶-凝胶法制备一系列不同Cu/V比例的Cu-V-O催化剂,利用XRD、BET、H₂-TPR等手段对催化剂进行了表征,并考察其催化燃烧甲苯的活性和抗硫性。结果表明,适量的Cu掺杂会提高催化剂比表面积,而且Cu-V可以形成Cu₃V₂O₈晶型结构,使V₂O₅晶格氧活动增加,提高催化剂氧化-还原能力。其中,Cu_0.15V_0.85催化剂表现出最佳的活性和抗硫性;通过TiO₂负载可以进一步提高催化剂对甲苯的催化燃烧活性和抗硫性。     

V2O5-CuO/TiO2催化剂中低温选择性催化NOx还原研究

浸渍法制备了一系列V₂O₅-CuO/TiO₂催化剂,考察中低温(200~300℃)条件下,以氨为还原剂选择性催化还原NO_x的活性,并利用比表面积及微孔孔隙分析仪(BET)、X射线衍射(XRD)对催化剂进行微观表征和分析。结果表明,500℃焙烧的2V16Cu/TiO₂催化剂展示了最佳的中低温催化活性和较宽的活性温度范围,在空速6.0×10⁴ h^-1、225℃条件下,NO_x转化率达97.3%,250℃时达到100%,温度升至300℃,催化活性仍保持在100%。XRD结果表明,随着Cu负载量的增加,逐渐显现CuO的特征峰。结合活性评价数据说明,CuO是VCu/TiO₂催化剂的主要活性组分之一,是降低SCR催化反应温度的重要因素。BET结果表明,CuO的负载对钒钛催化剂的表面结构有较大影响。耐硫性实验结果表明,添加钒氧化物制备的2V16Cu/TiO₂催化剂的抗硫性能有所改善。     

硬模板法制备铈基复合氧化物及其对甲苯燃烧的催化性能

采用硬模板法制得CeM-HT(M=Cu、Mn、Fe和Co)复合氧化物催化剂,借助XRD、BET、O₂-TPD和H₂-TPR研究了催化剂的物理化学性质,通过甲苯催化燃烧探针反应评价了催化剂的催化性能。结果表明,CuO、MnO_x、FeO_x和Co₃O₄能溶入CeO₂晶格形成Ce-O-Cu、Ce-O-Mn、Ce-O-Fe和Ce-O-Co固溶体,Cu和Mn离子的溶入导致CeO₂晶格发生了较大程度的晶格畸变,Fe和Co离子对CeO₂晶格的影响较小,且在CeCo-HT氧化物催化剂中还存在微量晶相Co₃O₄。所制得的CeM-HT氧化物催化剂表现出了优越的甲苯催化燃烧性能,在反应温度为300、270、260和230 ℃时,CeFe-HT、CeCo-HT、CeMn-HT和CeCu-HT氧化物催化剂上甲苯的催化燃烧转化率分别达93.7%、95.0%、96.5%和95.0%以上。Ce基复合氧化物催化剂的甲苯催化燃烧活性顺序与其氧脱附性能、储氧性能和可还原性能具有正相关性,遵从顺序为CeCu-HT > CeMn-HT > CeCo-HT > CeFe-HT。     

Fe改性Mn/CeO2催化剂低温下同时脱硝与脱甲苯实验研究

本研究采用浸渍法制备了Fe改性的Mn/CeO₂催化剂,并测试了催化剂在低温条件下同时脱硝与脱甲苯的性能。结果表明,Fe₅Mn/CeO₂催化剂表现出最佳的催化性能,甲苯的转化效率在175℃达到90%,NO转化率在95-300℃达到90%。通过BET、SEM、XRD、XPS、H₂-TPR、NH₃-TPD和O₂-TPD等表征手段对催化剂的理化性质进行分析。XPS结果表明,Fe₅Mn/CeO₂催化剂中Ce³⁺和Mn⁴⁺的含量增加,促进氧空位和不饱和化学键的形成,提供了更多的活性位点,从而有利于在低温下高效脱除NO和甲苯。H₂-TPR、NH₃-TPD和O₂-TPD表征表明,与其他催化剂相比,Fe₅Mn/CeO₂催化剂具有优异的氧化还原能力、更强的酸性和更好的氧迁移能力。此...     

铈改性CuMn/Al2O3/堇青石整体催化剂的甲苯催化燃烧性能研究(英文)

本研究以堇青石为载体,采用超声浸渍法制备了一系列CuMnCe_x/Al₂O₃/堇青石整体式催化剂,同时,通过N₂吸附-脱附、XRD、SEM、EDX、H₂-TPR、O₂-TPD、XPS和EPR等方法对样品的物理、化学性质进行了系统的表征分析。实验结果表明,CuMnCe_x/Al₂O₃/堇青石整体式催化剂中的Ce含量明显影响甲苯催化燃烧性能。其中,CuMnCe₂/Al₂O₃/堇青石整体式催化剂对甲苯氧化具有最高活性,当甲苯浓度为1 g/L、空速为78000 mL/(g·h)、温度为263℃时甲苯转化率达到90%,究其原因为CeO₂在CuMnO_x上分散均匀,不仅提高了氧空位的浓度和氧物种的迁移率,还增强了催化剂的低温还原性。同时,CuMnCe₂/Al₂     

不同前驱物制备的MnOx/TiO2联合O3催化氧化NO性能

分别以乙酸锰（MnAc）、氯化锰（MnCl₂）和硝酸锰（Mn（NO₃）₂）为前驱物,采用浸渍法制备MnAc/TiO₂、MnCl/TiO₂和MnN/TiO₂三种催化剂,并采用氮吸附、SEM、H₂-TPR、O₂-TPD、XRD和XPS进行表征。在固定床反应器上研究了三种催化剂的联合臭氧催化氧化NO性能。结果表明,以乙酸锰为前驱物制备的MnAc/TiO₂催化剂联合臭氧催化氧化NO活性最高;MnAc/TiO₂催化剂颗粒分散性好,比表面积相对较大,催化剂表面Mn³⁺较多,因而具有较高的催化活性。     

溶胶凝胶法由细菌纤维素制备CuCe_(0.75)Zr_(0.25)O_x复合氧化物及其低温催化降解甲苯性能

以绿色廉价的天然椰果细菌纤维素(BC)为造孔剂,采用溶胶凝胶法制备了CuCe_(0.75)Zr_(0.25)O_x复合氧化物催化剂,通过TG/DTG、N2低温物理吸脱附、XRD、H_2-TPR、O_2-TPD和Raman等手段对催化剂进行了表征,并对其在固定床上挥发性有机物(VOCs)降解的催化性能进行了研究。结果表明,利用BC精细的纤维网状结构和亲水性能与活性金属盐溶液形成凝胶,可有效制备介孔结构的复合氧化物催化剂。制备过程中,凝胶形式和成胶温度对催化剂降解甲苯的活性有较大影响;采用醇凝胶形式在70℃时制备的ACCZ-70催化剂完全降解甲苯的温度为205℃,明显低于已有文献报道的催化剂,这主要归因于该催化剂具有良好的低温还原性和高达0.81的氧空穴浓度。而采用水凝胶制备的催化剂降解甲苯时,在120-140℃存在吸附现象。     

Ce/Zr物质的量比对Ru/CexZr1-xO2催化剂的性质及其湿式氧化苯酚性能的影响

采用溶胶凝胶法制备了系列不同Ce/Zr物质的量比的Ru/Ce_xZr_1-xO₂催化剂,通过X射线衍射（XRD）、氮气吸附-脱附、拉曼（Raman）光谱、储氧能力（oxygen storage capacity,OSC）、热重（TG）以及吡啶红外（Py-FTIR）等手段对其进行了表征,考察了该催化剂在湿式氧化苯酚反应中的性能。结果表明,ZrO₂可与CeO₂形成固溶体;随着ZrO₂掺杂量的增加,Ce_xZr_1-xO₂固溶体的OSC值增大。相比于CeO₂,掺杂ZrO₂后催化剂表面的L酸量明显增多。催化剂湿式氧化（catalytic wet air oxidation,CWAO）性能与OSC和表面酸性均有密切的关系：催化剂表面的L酸有利于苯酚氧化生成CO₂,而OSC过高会导致催化剂表面积炭,使催化剂失活。当ZrO₂掺杂量为25%时,在160℃、2 MPa纯氧条件下,催化氧化苯酚5 h后,苯酚转化率和总有机碳（total organic carbon,TOC）去除率分别为100%和99%,说明该催化剂具有优异的苯酚氧化性能。     

钾改性Mn/Ce0.65Zr0.35O2催化剂催化氧化甲苯

Volatile organic compounds (VOCs) are both harmful to human health and the environment; however, catalytic combustion offers a promising method for VOC purification because of its high efficiency without secondary pollution. Although manganese-based catalysts have been well studied for VOC catalytic oxidation, their catalytic activity at low temperature must be improved. Alkali metals as promoters have the potential to modulate the electronic and structural properties of the catalysts, improving their catalytic activity. Herein, a Ce_0.65Zr_0.35O₂ support was prepared by co-precipitation and MnO_x/Ce_0.65Zr_0.35O₂ catalysts were obtained through the incipient-wetness impregnation method. The catalytic properties of K-modified MnO_x/Ce_0.65Zr_0.35O₂ for toluene oxidation with different molar ratios of K/Mn were investigated. In addition, the catalysts were characterized by XRD, UV/visible Raman, Hydrogen temperature program reduction (H₂-TPR), Oxygen temperature programmed desorption (O₂-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance FTIR spectroscopy (DRIFTS) experiments. The results showed that alkali metal doping with K significantly improved the catalytic activity. In particular, when the molar ratio of K/Mn was 0.2, the monolith catalyst Mn/Ce_0.65Zr_0.35O₂-K-0.2 exhibited the best performance with the lowest complete conversion temperature T₉₀ of 242 ℃ at a GHSV of 12000 h⁻¹. The XRD results suggested that MnO_x was uniformly distributed on the surface of the catalyst and that Mn⁴⁺ partially reduced to Mn³⁺ on the addition of K. The Raman spectrum demonstrated that with increasing K content, both the β- and α-MnO₂ phases coexisted on the Mn/Ce_0.65Zr_0.35O₂-K-0.2 catalyst, increasing the number of surface defect sites. The H₂-TPR experiment results confirmed that Mn/Ce_0.65Zr_0.35O₂-K-0.2 exhibited the lowest reduction temperature and good reducibility. From the O₂-TPD experiments, it was clear that Mn/Ce_0.65Zr_0.35O₂-K-0.2 contained the most surface adsorbed oxygen species and excellent lattice oxygen mobility, which benefitted the toluene oxidation activity. In addition, the XPS results suggested that the content of surface adsorbed oxygen species of the Mn/Ce_0.65Zr_0.35O₂-K-0.2 catalyst was the highest among all the tested samples. In addition, toluene-TPSR in N₂ as measured by in situ DRIFTs analysis demonstrated that available lattice oxygen was present in the Mn/Ce_0.65Zr_0.35O₂-K-0.2 catalyst. Therefore, the Mn/Ce_0.65Zr_0.35O₂-K-0.2 catalyst exhibited the best redox properties and oxygen mobility of the prepared samples and showed excellent activity toward toluene oxidation. Therefore, it was concluded that the addition of an appropriate amount of K improved the redox performance of the catalyst and increased the number of surface defect sites and mobility of the lattice oxygen of the catalyst as well as the concentration of the surface active oxygen species, thereby significantly improving catalytic ability.     

同晶取代法制备Cu-Ni双金属催化剂及其催化CO加氢合成乙醇性能

采用定向同晶取代法制备了一系列镍孔雀石前驱体的Cu-Ni双金属催化剂。考察了前驱体结构以及催化剂表面组成对催化剂催化性能的影响,并采用浆态床反应器对催化剂的CO加氢制乙醇性能进行评价。实验结果表明,采用定向同晶取代法可以制备出（Cu,Ni）₂CO₃（OH）₂纯物相,取代后的Ni²⁺主要富集在前驱体（Cu,Ni）₂CO₃（OH）₂表面。焙烧后形成的（Cu_x,Ni_1-x）O固溶体均匀地分散在CuO晶体结构中。还原后的催化剂中Cu、Ni相互均匀分散形成活性界面,促进了低碳醇的合成。其中,不连续分布的Ni活性位点阻止了碳链的进一步增长,从而提高了乙醇选择性。当Ni/Cu原料比为45：100时,（Cu_x,Ni_1-x）O固溶体与CuO之间有较强的相互作用,表现出最好的反应活性和乙醇选择性。     

Ho掺杂对Mn-Ce/TiO_2低温SCR催化剂的脱硝性能影响

采用浸渍法制备了五种掺杂不同比例的Ho的低温选择性催化还原(SCR)催化剂Mn0.4Ce0.07Hox/TiO_2。研究了Ho的引入对于Mn-Ce/TiO_2催化剂低温脱硝性能的影响,并采用XPS、XRF、BET、XRD、NH3-TPD等手段对催化剂的物理化学性质进行表征。结果表明,掺杂适量的Ho能够有效提高Mn-Ce/TiO_2催化剂的低温脱硝性能,当Ho/Ti掺杂比例为0.1时催化剂Mn0.4Ce0.07Ho0.1/TiO_2活性表现最佳,在200℃左右催化效率达到最高,为91.17%,在140-240℃催化效率达到80%以上。结果表明,Ho的掺杂能够增大催化剂的比表面积,提高催化剂化学吸附氧的浓度以及Ce的附着量。     

Decomposition of toluene using an atmospheric pressure plasma/TiO2 catalytic system

Application of atmospheric pressure plasma as an alternative technology for the destruction of toluene is demonstrated in this study. Used TiO₂ colloidal solution was obtained by an improved sol–gel method, and coated on glass beads to prepare decomposition of toluene. The physical property of synthesized TiO₂ catalyst film was analyzed by XRD and SEM spectroscopy. From these results, it was identified that the catalyst film exhibited anatase structure with particle size of about 50–100 nm after calcination at 500 °C for 1 h. The decomposition of toluene in TiO₂/O₂ plasma system was investigated. Amounts of the catalyst and toluene concentration were fixed as 3 wt.% and 1000 ppm, respectively. The analyses for performance of toluene decomposition and intermediates in reaction were done by the in situ method using the mass spectroscopy and gas chromatography. The toluene of 40% was decomposed at pulse voltage of 13 kV in the only O₂ plasma condition without TiO₂ catalyst. Furthermore, the conversion enhanced remarkably in the TiO₂/O₂ plasma system, and it reached 70% at pulse voltage of 13 kV after 120 min. This result was very notable compared with that in photocatalytic system, with below 40% after 120 min reaction.     

固体酸WO3/TiO2负载锂锰催化剂组成对其甲烷氧化偶联反应性能的影响

The selective oxidation of methane to basic petrochemicals (ethylene and ethane) is desirable and has attracted extensive research attention. The oxidative coupling of methane (OCM) is considered a promising one-step route for the production of C₂ compounds (ethylene and ethane) from methane, and has been the focus of industrial and fundamental studies. It is widely accepted that the composition is a crucial factor governing the activity of a catalyst system. It was found that the phase structures, basicity, existing status and distribution of the active components, oxygen species, and chemical states of the catalyst were influenced by the composition and ratio, resulting in different catalytic performances for the OCM. In this study, a series of solid acid WO₃/TiO₂-supported lithium-manganese oxide catalysts for OCM were synthesized via the impregnation method. The impacts of diverse compositions, such as the individual contents (Li and Mn) and dual contents (Li-Mn), on the OCM were investigated in detail, using inductively coupled plasma optical emission spectrometry, X-ray diffraction, high-resolution transmission electron microscopy, CO₂-temperature-programmed desorption, O₂-temperature-programmed desorption, H₂-temperature-programmed reduction, Raman spectroscopy, X-ray photoelectron spectroscopy, and CH₄-temperature-programmed surface reaction. The addition of Li content to the catalyst not only led to the anatase-to-rutile crystal structure transformation of TiO₂, and the reduction of the high-valence-state Mn species to low-valence-state Mn, but also increased the content of surface lattice oxygen and decreased the surface basicity. The observed effects on the structures and catalytic performance suggest that the Li content is helpful in suppressing the formation of completely oxidized CO₂, and increases the C₂ selectivity. Moreover, increasing the Li content of the catalyst facilitated the mobility of the lattice oxygen, which triggered the promotion of CH₄ activation, thereby enhancing the OCM catalytic performance. The Mn content acted as the active sites for OCM; therefore, the performance of the catalyst was closely related to the Mn concentration and valence state. However, the WO₃/TiO₂-supported catalyst with excessive Mn content exhibited a high surface basicity, high valence state of Mn, and low abundant lattice oxygen, which was unfavorable for C₂ selectivity. The Raman spectroscopy results revealed that MnTiO₃ was formed due to the co-existence of Li and Mn on WO₃/TiO₂, and played an essential role in improving the low-temperature OCM performance. There was a synergic effect of the Li and Mn components on the OCM. The optimal performance (16.3% C₂ yield) was achieved over the WO₃/TiO₂-supported lithium-manganese catalyst with n(Li) : n(Mn) = 2 : 1 at 750 ℃.     

Mn含量对CeO2-ZrO2-MnOx催化剂甲苯氧化净化性能的影响

采用氧化还原沉淀法制备了一系列CeO_2-ZrO_2-MnO_x催化剂(CZM_X,X为Mn在催化剂总金属中的摩尔含量),探讨了Mn含量对CZM_X催化甲苯燃烧性能的影响。结果表明,CZM_(0.6)催化剂具有最好的活性,在230℃下即可实现甲苯的完全转化。XRD表征结果发现,随着锰掺杂量的增加,CZM_X催化剂结晶度先降低后增加。H_2-TPR表征结果表明,随着Mn含量的增加,Ce-Zr-Mn之间的相互作用力先增强后减弱。CZM_(0.6)结晶度最差,金属之间相互作用力最强,表面氧物种更易溢出;同时,Raman和O_2-TPD表征结果也证明CZM_(0.6)催化剂上具有较高的表面氧空位浓度,有利于催化剂表面活性氧物种的迁移,促进了甲苯的氧化。此外,通过in-situ DRIFTS对中间产物进行观测,发现苯甲酸盐是CZM_(0.6)催化剂上甲苯氧化反应的重要中间体;在O_2参与下,苯甲酸盐可迅速转化为CO_2和H_2O。     

Ln2Zr2O7 compounds (Ln=La,Pr, Sm,Y) with varied rare earth A sites for low temperature oxidative coupling of methane

The replacement of Ln site with different rare earth cations alters the crystalline phases of Ln₂Zr₂O₇, which in turn influences the surface active oxygen and alkaline sites significantly. The abundance and the interaction of the two types of sites determine the OCM reaction performance.