MgO、CaO助剂对CO2加氢制备甲醇CuO-ZnO-Al2O3催化剂性能的影响

采用共沉淀法制备了MgO、CaO改性CuO-ZnO-Al2O3催化剂,通过XRD、N2物理吸附-脱附、TG-DTG、H2-TPR、CO2-TPD等表征手段,探讨助剂MgO、CaO添加对催化剂前体物相组成及催化剂微观结构的影响,考察了CO2加氢制备甲醇反应中MgO、CaO改性CuO-ZnO-Al2O3催化剂的性能。结果表明,CaO改性催化剂前体中形成的锌孔雀石相(Cu,Zn)2CO3(OH)2、绿铜锌矿相(Zn,Cu)5(CO3)2(OH)6,促进了催化剂中Cu-Zn协同活性位数量增加,同时助剂CaO的添加降低了催化剂中CuO和ZnO的晶粒度,增大了催化剂比表面积,改善了铜组分的表面分散度,有利于催化剂活性提高;MgO改性催化剂前体生成了绿铜锌矿相(Zn,Cu)5(CO3)2(OH)6,但没有锌孔雀石相(Cu,Zn)2CO3(OH)2生成,焙烧后催化剂中Cu-Zn协同作用较弱,此外MgO改性后催化剂比表面积减小,催化反应活性降低。MgO、CaO作为碱性助剂,调变了催化剂表面的碱强度和碱中心浓度,CaO改性催化剂的表面碱强度大于MgO改性催化剂,与CaO、MgO的碱性强度顺序一致,即CaO>MgO。     

Cu/Zn比对CuO/ZnO/ZrO_2催化CO_2加氢合成甲醇性能的影响

研究了不同Cu/Zn摩尔比对CO2加氢合成甲醇催化性能的影响。采用草酸凝胶共沉淀法制备了一系列不同Cu/Zn摩尔比的Cu O/Zn O/Zr O2催化剂,考察不同温度及Cu/Zn摩尔比对催化性能的影响,并结合X射线衍射(XRD)、N2物理吸附、程序升温还原(H2-TPR)和程序升温脱附(H2/CO2-TPD)技术对催化剂的结构和性质进行表征。结果表明:适宜的Cu/Zn摩尔比可以提高催化剂的反应性能。在513 K,2.0 MPa,n(H2)/n(CO2)=3/1和GHSV=4 800 h-1反应条件下,当R(Cu/Zn)=4时,Cu O/Zn O/Zr O2催化剂反应性能最好,CO2转化率高达17.8%,甲醇选择性高达67.8%。     

稀土改性的非晶态镍基催化剂对CO_2甲烷化反应的研究

以无定形的ZrO2为载体,非晶态金属Ni为活性组分,稀土作为助剂,考察了不同稀土对镍基催化剂的改性作用,采用XRD、SEM、NH3-TPD等技术对催化剂进行了表征。结果表明,稀土对镍基催化剂的CO2甲烷化活性有明显的促进作用,反应温度为623K时,CO2转化率提高了22.7%。稀土改性后的催化剂颗粒较小且分布均匀,酸性增强。     

铜/氧化锆催化剂的制备及应用研究进展

介绍了Cu/ZrO2催化剂的制备方法,阐述了助剂对Cu/ZrO2催化剂物化及催化性能的影响,综述了Cu/ZrO2催化剂在CO和/或CO2加氢合成甲醇、醇类水蒸气重整制氢、二乙醇胺脱氢合成亚氨基二乙酸盐、环己醇脱氢制环己酮和环己醇还原氨化制环己胺反应中的应用。     

稀土氧化物修饰的Cu-ZnO-Al2O3/HZSM-5催化剂二氧化碳加氢一步制备二甲醚的研究

本文采用高压固定床反应装置考察了添加2%稀土氧化物(La2O3和CeO2)的Cu-ZnO-Al2O3/HZSM-5催化剂CO2加氢一步合成二甲醚的催化性能。XRD和H2-TPR结果分析发现,添加稀土氧化物后阻止了部分Cu2+还原为非晶态Cu。在513K,反应压力为3.0MPa,反应空速为1000h-1的条件下,考察了CO2加氢一步合成二甲醚的催化性能。结果表明,添加La2O3和CeO2后,催化剂的催化活性以及二甲醚的选择性均大幅提高,反应20h,CO2转化率以及二甲醚选择性变化较小,说明该催化剂稳定性较好。     

锰和镧助剂对二乙醇胺氧化脱氢制亚氨基二乙酸Cu/ZrO2催化剂的改性作用

采用共沉淀法制备了掺杂锰、镧的Cu/ZrO2催化剂,考察了锰和镧助剂对Cu/ZrO2催化二乙醇胺氧化脱氢制亚氨基二乙酸性能的影响。采用XRD(X射线粉末衍射),TPR(程序升温还原),N2O滴定,N2吸附-脱附等方法考察了助剂改性后催化剂的结构和表面性质的变化。结果表明,引入锰助剂后催化剂比表面积从105 m2.g-1增大到143 m2.g-1,活性Cu的分散度从36.5%提高到53.6%;镧助剂的引入阻滞了金属Cu的聚集长大,延缓了催化剂晶化速度;锰、镧共同引入时表现出协同作用,不但使活性Cu的分散度提高,同时催化剂晶化速度减慢,从而提高了催化剂循环使用性能。     

ZrO_2对二氧化碳加氢合成二甲醚催化剂性能的影响

采用湿混法制备了一系列不同ZrO2含量的CuO-ZnO-Al2O3-ZrO2/HZSM-5复合催化剂,其中CuO-ZnO-Al2O3-ZrO2与HZSM-5分子筛(硅铝比为25)的质量比为2:1,CuO-ZnO-Al2O3-ZrO2(CuO/ZnO/Al2O3=3/6/1质量比)组分采用改进的两步共沉淀法制备。系统考察了ZrO2对CuO-ZnO-Al2O3-ZrO2/HZSM-5复合催化剂CO2加氢合成二甲醚反应性能的影响。研究表明ZrO2主要作为结构助剂改善了CuO-ZnO-Al2O3-ZrO2/HZSM-5复合催化剂对于CO2加氢合成二甲醚的催化性能。     

CuO/Al2O3催化剂上CO还原NO反应条件的研究

为减小工业废气中氮氧化物对环境的污染,以多价态金属助剂修饰的Cu/Al₂O₃为催化剂,采用以CO为还原剂的催化还原法进行消除氮氧化物的研究,考察工艺条件对催化剂反应性能的影响。结果表明,反应温度240 ℃即可实现NO的完全转化,较低空速有利于催化剂长周期稳定运行,助剂最佳质量分数为6%,降低或提高助剂含量均不利于NO的完全转化,体系中CO含量影响催化剂性能,CO含量过高会打破催化剂活性中间体的动态平衡,导致催化剂快速失活,应严格控制CO含量。     

用于CO还原NO的CuO/Al_2O_3催化剂的制备及性能评价

采用溶胶-凝胶法制备了CuO/Al_2O_3催化剂,并用CeO_2、Co_2O_3及Cr_2O_3分别对其进行了改性。利用BET及XRD对制备的催化剂进行了表征,考察了Cu O负载量、焙烧温度、CO/NO摩尔比及反应温度对Cu O/Al_2O_3催化剂催化CO还原NO反应的影响。研究结果表明,Cu O的适宜负载量为8%,焙烧温度为750℃时,催化剂的活性最高;CO与NO摩尔比为1.2时,在相同反应温度条件下,NO的脱除率较高;当其他反应条件保持不变时,反应温度越高越有利于NO的还原脱除。     

ZrO2-Al2O3复合载体对镍基催化剂甲烷化性能的影响

采用分步浸渍法制备了不同ZrO2载量的Ni/ZrO2-Al2O3催化剂,利用N2物理吸附、X射线衍射(XRD)、H2程序升温还原(H2-TPR)、H2程序升温脱附(H2-TPD)、程序升温氧化(TPO)等手段对催化剂的结构进行表征,并考察了其在低H2/CO比(H2/CO约为1)下CO甲烷化的催化性能。结果表明,ZrO2助剂可削弱NiO与载体Al2O3间的相互作用,抑制镍铝尖晶石的生成。适量ZrO2的引入有助于提高活性组分Ni的还原度和分散度,对催化剂的甲烷化性能有促进作用。通过分析反应后催化剂上的积炭性质,发现ZrO2的加入能有效地抑制低活性碳物种的生成,提高催化剂的抗积炭能力,从而改善催化剂的稳定性。     

ZrO2/SiO2- and La2O3/Al2O3-supported platinum catalysts for CH4/CO2 reforming

Surface-phase ZrO₂ on SiO₂ (SZrOs) and surface-phase La₂O₃ on Al₂O₃ (SLaOs) were prepared with various loadings of ZrO₂ and La₂O₃, characterized and used as supports for preparing Pt/SZrOs and Pt/SLaOs catalysts. CH₄/CO₂ reforming over the Pt/SZrOs and Pt/SLaOs catalysts was examined and compared with Pt/Al₂O₃ and Pt/SiO₂ catalysts. CO₂ or CH₄ pulse reaction/adsorption analysis was employed to elucidate the effects of these surface-phase oxides.

The zirconia can be homogeneously dispersed on SiO₂ to form a stable surface-phase oxide. The lanthana cannot be spread well on Al₂O₃, but it forms a stable amorphous oxide with Al₂O₃. The Pt/SZrOs and Pt/SLaOs catalysts showed higher steady activity than did Pt/SiO₂ and Pt/Al₂O₃ by a factor of three to four. The Pt/SZrOs and Pt/SLaOs catalysts were also much more stable than the Pt/SiO₂ and Pt/Al₂O₃ catalysts for long stream time and for reforming temperatures above 700 °C. These findings were attributed to the activation of CO₂ adsorbed on the basic sites of SZrOs and SLaOs.     

TiO2-SiO2 and V2O5/TiO2-SiO2 catalyst: Physico-chemical characteristics and catalytic behavior in selective catalytic reduction of NO by NH3

TiO₂-SiO₂ with various compositions prepared by the coprecipitation method and vanadia loaded on TiO₂-SiO₂ were investigated with respect to their physico-chemical characteristics and catalytic behavior in SCR of NO by NH₃ and in the undesired oxidation of SO₂ to SO₃, using BET, XRD, XPS, NH₃-TPD, acidity measurement by the titration method and activity test. TiO₂-SiO₂, compared with pure TiO₂, exhibits a remarkably stronger acidity, a higher BET surface area, a lower crystallinity of anatase titania and results in allowing a good thermal stability and a higher vanadia dispersion on the support up to high loadings of 15 wt% V₂O₅. The SCR activity and N₂ selectivity are found to be more excellent over vanadia loaded on TiO₂-SiO₂ with 10–20 mol% of SiO₂ than over that on pure TiO₂, and this is considered to be associated with highly dispersed vanadia on the supports and large amounts of NH₃ adsorbed on the catalysts. With increasing SiO₂ content, the remarkable activity decrease in the oxidation of SO₂ to SO₃, favorable for industrial SCR catalysts, was also observed, strongly depending on the existence of vanadium species of the oxidation state close to V⁴⁺ on TiO₂-SiO₂, while V⁵⁺ exists on TiO₂, according to XPS. It is concluded that vanadia loaded on Ti-rich TiO₂-SiO₂ with low SiO₂ content is suitable as SCR catalysts for sulfur-containing exhaust gases due to showing not only the excellent de-NO_x activity but also the low SO₂ oxidation performance.     

还原条件对三元载体加氢催化剂加氢脱氮性能的影响

用原位溶胶凝胶法制备了不同TiO：含量的MoP／TiO2-SiO2-Al2O3催化剂,对含喹啉的模型化合物,在连续同定床反应器上进行。THDN活性评价（反应温度为300～400℃,反应压力为3．0MPa）。在不同还原条件下,对催化剂进行加氢脱氮活性评价。结果表明：还原条件对MoP／TiO2-SiO2-Al2O3催化剂加氢活性有较大影响,评价确定的最佳还原条件为：还原气速60mL／min,还原温度为600℃。     

Photocatalytic activity of Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions

Cu₂O/TiO₂, Bi₂O₃/TiO₂ and ZnMn₂O₄/TiO₂ heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu₂O, Bi₂O₃ and ZnMn₂O₄ are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu₂O/TiO₂ and Bi₂O₃/TiO₂ by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed.     

SO2 resistant antimony promoted V2O5/TiO2 catalyst for NH3-SCR of NOx at low temperatures

To get the low temperature sulfur resistant V₂O₅/TiO₂ catalysts quantum chemical calculation study was carried out. After selecting suitable promoters (Se, Sb, Cu, S, B, Bi, Pb and P), respective metal promoted V₂O₅/TiO₂ catalysts were prepared by impregnation method and characterized by X-ray diffraction (XRD) and Brunner Emmett Teller surface area (BET-SA). Se, Sb, Cu, S promoted V₂O₅/TiO₂ catalysts showed high catalytic activity for NH₃ selective catalytic reduction (NH₃-SCR) of NO_x carried at temperatures between 150 and 400 °C. The conversion efficiency followed in the order of Se > Sb > S > V₂O₅/TiO₂ > Cu but Se was excluded because of its high vapor pressure. An optimal 2 wt% ‘Sb’ loading was found over V₂O₅/TiO₂ for maximum NO_x conversion, which also showed high resistance to SO₂ in presence of water when compared to other metal promoters. In situ electrical conductivity measurement was carried out for Sb(2%)/V₂O₅/TiO₂ and compared with commercial W(10%)V₂O₅/TiO₂ catalyst. High electrical conductivity difference (ΔG) for Sb(2%)/V₂O₅/TiO₂ catalyst with temperature was observed. SO₂ deactivation experiments were carried out for Sb(2%)/V₂O₅/TiO₂ and W(10%)/V₂O₅/TiO₂ at a temperature of 230 °C for 90 h, resulted Sb(2%)/V₂O₅/TiO₂ was efficient catalyst. BET-SA, X-ray photoelectron spectroscopy (XPS) and carbon, hydrogen, nitrogen and sulfur (CHNS) elemental analysis of spent catalysts well proved the presence of high ammonium sulfate salts over W(10%)/V₂O₅/TiO₂ than Sb(2%)/V₂O₅/TiO₂ catalyst.     

Phase diagram of the Al2O3–ZrO2–Nd2O3 system

The phase diagram of the Al₂O₃–ZrO₂–Nd₂O₃ system was constructed in the temperature range 1250–2800 °C. The liquidus surface of the phase diagram reflects the preferentially eutectic interaction in the system. Two new ternary and one new binary eutectics were found. The minimum melting temperature is 1675 °C and it corresponds to the ternary eutectic Nd₂O₃·11Al₂O₃ + F-ZrO₂ + NdAlO₃. The solidus surface projection and the schematic of the alloy crystallization path confirm the preferentially congruent character of phase interaction in the ternary system. The polythermal sections present the complete phase diagram of the Al₂O₃–ZrO₂–Nd₂O₃ system. No ternary compounds or regions of remarkable solid solution were found in the components or binaries in this ternary system.     

甲醇/H2O/H2O2/1,3,5-三甲苯/磷酸三辛酯五元系液液平衡的实验数据

测定了常压、 4 0℃下甲醇 /H₂ O/H₂ O₂ /1,3,5 -三甲苯 /磷酸三辛酯五元系液液平衡数据 ,分别用UNIQUAC模型和NRTL模型对实验数据进行了关联 ,取得了较满意的结果     

SnO_2-MnO_2-Sb_2O_3体系固溶体相图初探

采用化学共沉淀方法制备了SnO2-MnO2-Sb2O3三元固溶体并对其相图进行了初步研究,绘制了固相线下SnO2-MnO2-Sb2O3三元体系相图,确定该类固溶体的类型及其形成机制。实验结果表明:该三元体系的相关系图中含有2个单相区、8个两相区和3个三相区。金红石型SnO2为主要化合物的1区和锡锑共存互溶形成的(Sn,Sb)O2ss化合物为主的2区这两个单相区中的氧化物可以作为耐腐蚀性强、导电性良好的阳极材料中间层。     

复合氧化物TiO2/SiO2性质研究

The nanometer particles of TiO2 and TiO2/SiO2 oxides were prepared by sol-gel and supercritical fluid drying method.The properties of TiO2 and TiO2/SiO2 were characterized by means of BET(Brunner-Emmett-Teller method), TEM(transmission electron microscopy), SEM(Scanning electron microscopy), XRD(X-ray differaction) and FTIR(Fourier transform-infrared) techniques.The effects of different preparation route,prehydrolysis and non-prehydrolysis,on the properties of TiO2/SiO2 oxide were also examined.Experimental results show that the termal stability of pure TiO2 is improved greatly when it is mixed with SiO2 in nanometer level.The composite TiO2/SiO2 oxides form Ti-O-Si chemical bonds,which creates new Broensted acidity stes.The acidity character is related to TiO2/SiO2 chemical composition and preparation methods.The acidity of TiO2/SiO2 oxides by prehydrolysis is greater than that of by non-prehydrolysis.Ti atom is rich on the surface of TiO2/SiO2.