TiO 2 –Al 2 O 3 as a support for propane partial oxidation over Rh

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四氯化钛生产

四氯化钛生产四氯化钛生产(培训教材) 黄诗才编二??八年五月二十八日 2011-03-31 10:23:46| 分类: 默认分类 | 标签: |字号大中小订阅前言四氯化钛是金属钛的生产、气相氧化法制取钛白粉以及医药和1000多种有机和无机钛化合物生产的主要中间产品。

目前四氯化钛消费在钛白工业上，每年达450万吨以上，消费在海绵钛生产上每年达50,60万吨。

其他领域主要供给云母钛珠光颜料、聚乙烯和聚丙烯等聚合剂生产，这两项需消费四氯化钛每年达8万吨以上。

为了适应四氯化钛生产需要，培养一支专业化的、熟练掌握四氯化钛生产的从职人员，编写了这本《四氯化钛生产》职工培训教材。

这本教材紧密联系四氯化钛生产实际，适合工人阅读。

除介绍了四氯化钛生产的基本原理、工艺流程及主要设备以外，也阐述了一些浅显的工艺方法的理论基础。

这本教材主要介绍高钛渣沸腾氯化工艺技术和铜除钒技术，只提及了熔盐氯化工艺和其他除钒工艺。

这本教材仍需要在四氯化钛工艺方法不断改进和完善的基础上，进行修改。

也恳请同行对教材中的不足之处予以指正。

目录第一章粗TiCl4生产 (1)第一节氯化过程的基本原理 (1)第二节影响氯化的因素 (6)第三节氯化工艺流程 (8)第四节氯化主要设备 (11)第五节技术操作 (15)第二章粗TiCl4的精制 (19)第一节粗TiCl4中的杂质 (20)第二节精制的原理和方法 (24)第三节精制工艺流程 (28)第四节精制主要设备 (30)第五节技术操作 (41)第三章三废的治理和利用 (45)第一节废气治理 (45)第二节酸性废水处理 (47)第三节氯化炉渣处理 (48)第一章粗四氯化钛生产四氯化钛是生产海绵钛、气相氧化法生产钛白、云母钛珠光颜料和多种有机和无机钛化合物生产的原料。

它是在有碳存在的条件下用氯气氯化高钛渣、金红石制得的。

目前工业上生产四氯化钛的方法有熔盐氯化和沸腾氯化二种，工业上一般都采用的是沸腾氯化生产工艺。

整体催化剂用于低浓度甲烷的催化燃烧

珂
日期：２００９年２月２日
1
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表21整体催化剂反应器与常规反应器的比较30table21comparisonbetweenmonolithicreactorandgeneralreactor整体催化剂反应器流化床反应器滴流床反应器能耗低中高有较高的压力降催化效率高有很薄的活性层高存在细小微粒低大颗粒需要高的压力降安全性高自排压反应器中易冷却低不易冷却操作难易程度中新的技术和方法正在发展简单简单催化剂装填量中具有开放的结构对于涂覆法较低中偏下高高密度的反应床催化剂分离容易难需要过滤容易催化剂再生难需要停机简单可在连续操作中进行中需要停机应用范围对气象反应广阔液相和多相反应较为受限广阔广阔整体催化剂用于低浓度甲烷的催化燃烧10整体催化剂及其反应器在化工反应中具有有利于提高传质与传热均匀性易于实现并逆流操作减小催化剂床层压力降和节省操作费用等特点有利于提高催化剂的活性和选择性
本人郑重声明：所呈交的学位论文，是本人在导师的指导下，独立进行研究工作所取得的成果。除文中已经注明引用的内容外，本论文不包含任何其他个人或集体已经发表或撰写过的作品成果。对本文的研究做出重要贡献的个人和集体，均已在文中以明确方式标明。本人完全意识到本声明的法律结果由本人承担。

钛铝复合氧化物载体的制备及应用

第9卷第6期2001年11月工业催化I NDU STR I AL CA TAL YS ISV o l111N o16　N ov.2001催化剂与载体制备钛铝复合氧化物载体的制备及应用Ξ张　晟1,卢冠忠1,毛东森1,2,陈庆龄2(1.华东理工大学工业催化研究所,上海200237;2.上海石油化工研究院,上海201208)摘　要:本文评述了T i O22A l2O3复合氧化物的制备方法,介绍了T i O22A l2O3复合氧化物作为催化剂载体应用于工业生产的现状。

关键词:T i O2;A l2O3;复合氧化物载体;负载型催化剂中图分类号:TQ426165 文献标识码:A 文章编号:100821143(2001)0620049204 Prepara tion and appl ica tion of titan i a-a lu m i na m ixed ox ideZH A N G S heng1,L U Guan2z hong1,M A O D ong2sen1,2,CH EN Q ing2ling2(1.In stitu te of Indu strial Catalysis,East Ch ina U n iversity of Science&T echno logy,Shanghai200237,Ch ina;2.S I NO PEC Shanghai R esearch In stitu te of Petrochem icalT echno logy,Shanghai201208,Ch ina)Abstract:P rep arati on m ethods fo r titan ia2alum ina m ixed ox ide w ere review ed.A pp licati on of titan ia2alum ina m ixed ox ide as catalyst suppo rt w as ou tlined,too.Key words:titan ia;alum ina;m ixed ox ide;suppo rtCLC nu m ber:TQ426165　D ocu m en t code:A　Article I D:100821143(2001)0620049204 在负载型催化剂中,载体对催化剂性能有着重要的影响。

光催化重整有机化合物制氢的研究进展

TiO2光催化重整甲醇制氢机理
CH3OH + h+ CH3O + H+ CH3O + 2h+ CHO + 2H+ CHO + h+ + H2O HCOOH + H+ HCOOH + 2h+ CO2 + 2H+ 2H+ + 2e- H2
D. F. Ollis et al., J.Catal, 1984, 88, 89. H. Al-Ekabi et al., Langmuir, 1989, 5, 250. C. Richard., J.Photochem.Photobiol A: Chem, 1993, 72, 179. C. Wang et al., J.Am.Chem.Soc., 2004, 126, 8094.
Seminar II
光催化重整有机化合物制氢的研究进展
报告人: 宗旭 2004级博士生
指导老师: 李灿院
士
大连化学物理研究所催化基础国家重点实验室
太阳能转化利用的途径
N. S. Lewis, Nature, 2001, 414, 589.
光电催化分解水制氢
TiO2 2hv 2e 2h
hv 表面复合 +
VB
hv
CB
H2
O2＋H+
CO2＋H＋
体相复合
+
或者 H2O
H+
有机物
分解水和有机物制氢的热力学对比
H 2O
H2 + 1/2 O2
ΔG
KJ/(mol C )
ΔG = 237 KJ/mol, E = -ΔG/nF = -1.23 eV

La_(2)O_(3)-Y_(2)O_(3)复掺制备高强韧Al_(2)O_(3)陶瓷基板

第42卷第6期Vol.42No.62021年12月Journal of Ceramics Dec. 2021收稿日期：2021‒07‒12。

修订日期：2021‒09‒14。

Received date: 2021‒07‒12. Revised date: 2021‒09‒14.基金项目：广东省“珠江人才计划”本土创新科研团队项目 Correspondent author: NIE Guanglin (1990-), Male, Ph.D.; (2017BT01C169)；广东省基础与应用基础研究基金项目(2020 WU Shanghua (1963-), Male, Ph.D., Professor.A1515010004)；绿色建筑材料国家重点实验室开放基金(2019 E-mail: **************************;************.cn GBM03)。

通信联系人：聂光临(1990-)，男，博士；伍尚华(1963-)，男，博士，教授。

DOI: 10.13957/ki.tcxb.2021.06.016La 2O 3-Y 2O 3复掺制备高强韧Al 2O 3陶瓷基板刘磊仁1，聂光临1，黄丹武1，赵振华1，包亦望2，伍尚华1(1. 广东工业大学机电工程学院，广东广州 510006；2. 中国建筑材料科学研究总院有限公司绿色建筑材料国家重点实验室，北京 100024)摘要：Al 2O 3作为应用最广的陶瓷基板，优异的力学强度、韧性与导热性能是确保其安全可靠服役的前提。

稀土金属氧化物(La 2O 3、Y 2O 3)掺杂是提升Al 2O 3陶瓷力学性能的有效方法，然而，单一掺杂的强化效果有限，因此，采用La 2O 3-Y 2O 3复掺的方法以望进一步提升Al 2O 3陶瓷基板的抗弯强度与断裂韧性，并在此基础上探讨了La 2O 3-Y 2O 3复掺对Al 2O 3陶瓷热导率的影响规律。

【条件】参考酸性条件下tio2ti光电极制备及光催化性能研究

文档来源为:从网络收集整理.word版本可编辑.欢迎下载支持. 【关键字】条件大学毕业论文（设计）题目：酸性条件下TiO2/Ti光电极制备及光催化性能研究姓名：学院：专业：班级：学号：指导教师：18 日毕业论文（设计）诚信声明本人声明：所呈交的毕业论文（设计）是在导师指导下进行的研究工作及取得的研究成果，论文中引用他人的文献、数据、图表、资料均已作明确标注，论文中的结论和成果为本人独立完成，真实可靠，不包含他人成果及已获得青岛农业大学或其他教育机构的学位或证书使用过的材料。

与我一同工作的同志对本研究所做的任何贡献均已在论文中作了明确的说明并表示了谢意。

论文（设计）作者签名：日期：年月日毕业论文（设计）版权使用授权书本毕业论文（设计）作者同意学校保留并向国家有关部门或机构送交论文（设计）的复印件和电子版，允许论文（设计）被查阅和借阅。

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本人离校后发表或使用该毕业论文（设计）或与该论文（设计）直接相关的学术论文或成果时，单位署名为青岛农业大学。

论文（设计）作者签名：日期：年月日目录3.2.6 不同TiO2/Ti光电极光催化性能........................................ 错误!未定义书签。

4 结论与建议................................................................................ 错误!未定义书签。

参考文献........................................................................................ 错误!未定义书签。

附录................................................................................................ 错误!未定义书签。

TiO_(2)的添加对铝铬固溶体烧结动力学的影响

LI Renjun, ZHANG Ling, ZHANG Xiaoxu, WANG Zhigang, HU Yujiang
( School of Materials and Metallurgy, Liaoning Science and Technology University, Anshan 114051, China)
Abstract: Aluminum chromium solid solution is widely used in refractory materials, but it’ s hard to achieve sintering and densification. Adding a certain amount of sintering additives can effectively improve its density, but the rule of grain growth in the densification process is still unclear. In this experiment, nano η-Al2 O3 and industrial chromium green were used as raw materials, with TiO2 as sintering aid and PVA as the binder, after being formed by cold isostatic pressing, the sintered aluminum chromium solid solution with the mole ratio of 1 ∶ 1 was prepared by solid phase sintering at 1 400 ℃ to 1 700 ℃ under normal pressure. The density, phase composition, microstructure, and average grain size of the sintered samples were analyzed by Archimedes method, XRD, SEM, and Nano measurer. On this basis, the effect of TiO2 on sintering kinetics of aluminum chromium solid solution was further calculated and studied. The results show that during the sintering process, the grain growth index and activation energy of Al2 O3 -Cr2 O3 and Al2 O3 -Cr2 O3 -2% TiO2 sintered systems decrease with the increase of temperature. The grain growth of Al2 O3 -Cr2 O3 system is mainly controlled by atoms crossing grain boundaries randomly and volume diffusion, the grain growth of the Al2 O3 -Cr2 O3 -2% TiO2 system is mainly controlled by volume diffusion. Compared with the two systems, it is found that the addition of TiO2 can decrease the grain growth index and activation energy of grain growth, and promote the grain growth and its development. Key words: nano-η-Al2 O3 ; aluminum chromium solid solution; solid phase sintering; sintering additive; grain growth; sintering kinetics

掺杂ZrO_2、TiO_2、γ－Al_2O_3对Pt、Pd／Al_2O_3燃烧

掺杂ZrO_2、TiO_2、γ－Al_2O_3对Pt、Pd／Al_2O_3燃
烧
周仁贤;朱波;徐晓玲;郑小明
【期刊名称】《环境科学学报》
【年(卷),期】1995(15)2
【摘要】运用ＸＲＤ、ＢＥＴ、ＤＴＡ等测试技求，研究并考察了掺杂ＺｒＯ＿２、ＴｉＯ＿２、ｒ－Ａｌ＿２Ｏ＿３对Ｐｔ－Ｐｄ／Ａｌ＿２Ｏ＿３燃烧催化剂性能的影响，结果表明，ＺｒＯ＿２对Ａｌ＿２Ｏ＿３晶相的γ型转为α型有明显的抑制作用，而ＴｉＯ＿２的添入则起促进作用；高温引起催化剂活性下降的主要原因是作为第一载体的Ａｌ＿２Ｏ＿３的比表面积和孔容减少以及Ａｌ＿２Ｏ＿３晶态从γ型转为α型所造成的。

【总页数】7页(P232-238)
【关键词】催化剂;氧化;钯;铂;第二载体;性能;废气治理
【作者】周仁贤;朱波;徐晓玲;郑小明
【作者单位】杭州大学催化研究所;浙江省物资学校
【正文语种】中文
【中图分类】O643.36;X701
【相关文献】
1.ZrO_2在Pd／Al_2O_3催化剂中的助剂作用 [J], 周仁贤;郑小明;葛玉平
2.金红石型钛白粉包覆ZrO_2/Al_2O_3膜制备高耐候性TiO_2颜料研究 [J], 邹建新;杨成
3.铝含量对Pd–S_2O_8^(2-)/ZrO_2–Al_2O_3固体超强酸催化剂的异构化性能的影响（英文） [J], 宋华;王娜;宋华林;李锋;金在顺
4.ZrO_2对超重力下燃烧合成Al_2O_3/ZrO_2(4Y)的影响 [J], 赵忠民;张龙;宋亚林;潘传增;曲振生;杨权
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因版权原因，仅展示原文概要，查看原文内容请购买。

Catalysis Letters 2009,131,1-2, 250-257

Propane Oxidative Dehydrogenation Over Ln–Mg–Al–O Catalysts (Ln 5Ce,Sm,Dy,Yb)Gheorghit ¸a Mitran ÆAdriana Urda ÆNathalie Tanchoux ÆFranc ¸ois Fajula ÆIoan-Cezar MarcuReceived:10March 2009/Accepted:4June 2009/Published online:23June 2009ÓSpringer Science+Business Media,LLC 2009Abstract Ln–Mg–Al mixed oxide catalysts (Ln =Ce,Sm,Dy,Yb)were prepared from layered double hydroxide precursors,characterized using XRD,N 2adsorption,TG-DTG,EDX,H 2-TPR and CO 2-TPD techniques and tested in the oxidative dehydrogenation of propane in the temperature range 450–600°C.For all the catalysts the conversion increases with increasing the reaction temper-ature while the propene selectivity decreases to the beneﬁt of carbon oxides for Ce-based system and of cracking products for the others.The best yields in propene were obtained with Dy-and Sm–Mg–Al–O catalysts.No corre-lation between the reducibility of the rare-earth cation and the catalytic performances was observed.A linear corre-lation between the catalyst basicity and the propene selectivity was evidenced.Keywords Oxidative dehydrogenation ÁPropane ÁRare-earth oxides ÁLayered double hydroxides1IntroductionThe oxidative dehydrogenation of propane to propene is one of the potentially important catalytic processes for theeffective utilization of light alkanes and has been thor-oughly studied in recent times [1–14],propene being an important raw material for the production of polypropyl-ene,acrylonitrile,acrolein and acrylic acid.In spite of this high number of studies there is no up to now a sufﬁciently active and selective catalyst for the oxidative dehydroge-nation of propane to propene that could be used at indus-trial scale.Thus,the development of a catalyst with a sufﬁciently high activity and selectivity is highly desirable.Heterogeneous catalysts for this reaction typically con-tain vanadium and molybdenum as the critical elements [1–9].Among other oxide systems,those containing rare-earth oxides are also reported as active and selective [14–16].It has been shown that c -Al 2O 3-supported rare-earth oxides (Y,Dy,Tb,Yb,Ce,Tm,Ho and Pr)are reactive in propane oxidative dehydrogenation,but propene selectivi-ties were relatively low,namely under 40%[14].Taking into consideration the electron-donating character of the oleﬁnic species,it was of interest to investigate whether the propene selectivity could be enhanced by increasing the catalyst basicity.For this reason we prepared Mg–Al mixed oxide-supported rare-earth oxides from layered double hydroxide (LDH)precursors and we studied their catalytic properties in the oxidative dehydrogenation of propane.The obtained results are presented in this paper.2Experimental 2.1Catalysts PreparationLn–Mg–Al–O (Ln =Ce,Sm,Dy,Yb)samples were pre-pared by coprecipitation of mixed metal nitrate solutions with an aqueous solution of NaOH (2M)at a constant pH of 10.Thus,an aqueous solution of Mg(NO 3)2Á6H 2O andG.Mitran ÁA.Urda ÁI.-C.Marcu (&)Department of Chemical Technology and Catalysis,Faculty of Chemistry,University of Bucharest,4-12,Blv.Regina Elisabeta,030018Bucharest,Romaniae-mail:marcu.ioan@unibuc.ro;ioancezar_marcu@ N.Tanchoux ÁF.FajulaInstitut Charles Gerhardt,UMR 5253CNRS/ENSCM/UM2/UM1,Mate´riaux Avance ´s pour la Catalyse et la Sante ´(MACS),Ecole Nationale Supe´rieure de Chimie,8,rue de l’Ecole Normale,34296Montpellier Cedex 5,FranceCatal Lett (2009)131:250–257DOI 10.1007/s10562-009-0057-1Al(NO3)3Á9H2O was contacted with the basic solution by dropwise addition of both solutions into a well-stirred beaker containing200cm3of rare-earth Ln nitrate solution at room temperature.Ln content,as atomic percent with respect to the cationic species,was equal to5and the Mg/Al atomic ratio was kept at3for all preparations.The addition of the alkaline solution and pH were controlled by pH-STAT Titrino(Metrohm).The precipitates formed were aged in their mother liquor overnight at80°C under stirring,separated by centrifugation,washed with deion-ized water until a pH of7and dried at80°C overnight. Dried samples were calcined in air at750°C during8h in order to form the corresponding mixed metal oxides which were used as catalysts.2.2Catalysts CharacterizationPowder X-Ray diffraction(XRD)spectra were obtained using a Siemens D5000Diffractometer and monochromatic Cu-K a radiation.They were recorded with0.02°(2h)steps over the3°–70°/angular range with1s counting time per step.The chemical composition of the samples was deter-mined by EDX microprobe on a Cambridge Stereoscan260 apparatus.The textural characterization was achieved using con-ventional nitrogen adsorption/desorption method,with a Micromeritics ASAP2010automatic analyzer.Prior to nitrogen adsorption,the samples were outgassed for8h at 523K.The thermal analysis(TG and DTG)was carried out using a Netzsch TG209device,in the following condi-tions:linear heating rate10°C min-1from room temper-ature to900°C,dynamic air atmosphere,Al2O3crucible, sample weight approximately20mg.Temperature-programmed desorption(TPD)of CO2was carried out using a Micromeritics Autochem model2910 instrument.Fresh calcined samples(100mg)were pre-treated in air at550°C before adsorption of the probe mol-ecule at100°C.During desorption,the sample was heated in a heliumﬂow(30mL min-1)at a ramp of10°C min-1.The amount of the probe molecule desorbed from the sample was estimated from the area under the peak after taking the thermal conductivity detector response into consideration.Hydrogen temperature-programmed reduction(H2-TPR) studies were carried out using a Micromeritics Autochem model2910instrument.Fresh calcined samples(100mg), placed in a U-shaped quartz reactor,were pretreated in air at 750°C before reduction.After cooling down to room tem-perature and introducing the reduction gas of3%H2/Ar,the sample was heated at a rate of10°C min-1from room temperature to800°C.The hydrogen consumption was estimated from the area under the peak after taking the thermal conductivity detector response into consideration. Calibration of TCD signal has been done with an Ag2O standard(Merck,reagent grade).Characterization of the samples has been performed before and,for some of them,after the catalytic test.2.3Catalytic TestingThe catalytic oxidative dehydrogenation of propane was carried out in aﬁxed bed quartz tube down-ﬂow reactor operated at atmospheric pressure.The internal diameter of the reactor tube was15mm.The catalyst was supported by quartz wool.The axial temperature proﬁle was measured using an electronic thermometer placed in a thermowell centered in the catalyst bed.Quartz chips were used toﬁll the dead volumes before and after the catalyst bed to minimize potential gas-phase reactions at higher reaction temperatures.The gas mixture consisting of propane and air was fed into the reactor at a volume hourly space velocity(VHSV)in the range of3,000–12,000h-1.The reaction temperature was varied between450and600°C, the propane-to-oxygen molar ratio,between1and4,and the catalyst bed volume was always kept to1cm3.In a typical reaction run,the reactor was heated to the desired temperature in theﬂow of reactants.The system was allowed to stabilize for about1h at the reaction tempera-ture before theﬁrst product analysis was made.Each run was carried out over a period of2–3h.The reaction products were analyzed in a Clarus500Gas-Chromato-graph equipped with a thermal conductivity detector(TCD) using an alumina column and aﬂame ionization detector (FID)using a CTR I column.Propene,CO,CO2and cracking products(methane and ethylene)were the major products formed under the reac-tion conditions.Conversion of propane and product selec-tivities were expressed as mol%on a carbon atom basis. The carbon balance was in all runs higher than95%.3Results and Discussion3.1Catalysts CharacterizationThe XRD patterns of the prepared precursors andﬁnal cat-alysts are displayed in Figs.1and2,respectively.Poorly crystallized layered hydrotalcite-type structures(JCPDS 37-0630),as generally observed for multicationic LDH, were detected on all dried precipitated samples labeled LnMgAl-LDH.The interlayer distance003equal to ca.8A˚, was consistent with the presence of nitrates as interlayered [17].Some of the samples,as Ce-,Sm-and DyMgAl-LDH, displayed lines corresponding to poorly crystallized CeO2 (JCPDS75-0076)Sm(OH)3(JCPDS83-2036)and Dy2O3Propane Oxidative Dehydrogenation Over Ln–Mg–Al–O Catalysts251(JCPDS22-0612),respectively.On the other hand,samples calcined at750°C exhibited,in all cases,lines correspond-ing to the MgAlO mixed oxide phase with the periclase-like structure(JCPDS-ICDD4-0829)and lines corresponding to CeO2(JCPDS75-0076),Sm2O3(JCPDS15-0813),Dy2O3 (JCPDS22-0612)and Yb2O3(JCPDS41-1106)phases for Ce-,Sm-,Dy-and Yb–Mg–Al–O mixed oxides,respec-tively.We note that XRD patterns of the samples after the catalytic test remained practically unchanged.The chemical compositions of the samples reported in Table1show that the rare-earth content was slightly higher than the nominal value and the Mg/Al atomic ratio varied between2.9for Ce–Mg–Al–O and3.9for Yb–Mg–Al–O.The speciﬁc surface areas of the catalysts were high,in the range102–160m2g-1.They are also reported in Table1. All the catalysts displayed type IV nitrogen adsorption/ desorption isotherms,according to IUPAC classiﬁcation, with a hysteresis loop characteristic of mesoporous materials [18]with a broad distribution of sizes.After the catalytic test, the speciﬁc surface areas of the catalysts remained practi-cally the same.The TG-DTG curves of YbMgAl-LDH precursor and of the corresponding oxide,Yb–Mg–Al–O,are presented in Fig.3.Theﬁrst weight loss in the TG-DTG curves of the HDL precursor(Fig.3a)is due to the elimination of loosely bound water and interlayer water molecules.The second weight loss is ascribed to the removal of hydroxyl groups in the metal hydroxide layers.The sample exhibited a net weight loss of43%up to900°C,with the second weight loss being larger than theﬁrst one.This is in accord with literature data for hydrotalcite-like materials[19–21]. In the case of the calcined oxide,the TG curve decreased continuously up to500°C but the DTG proﬁle presented two well-deﬁned signals at90and185°C and a broad signal in the range250–500°C(Fig.3b).The total weight loss for the calcined sample was smaller,namely15%.This may be due to the adsorption of water and carbon dioxide from the environmental air at the oxide surface and sug-gests that the catalyst must be activated in the reactor before the catalytic test at temperatures higher than500°C for cleaning its surface.The basicity of the catalysts was determined by tem-perature-programmed desorption of CO2(CO2-TPD),the proﬁles obtained being shown in Fig.4.These proﬁles were deconvoluted in three CO2desorption peaks,having the maximum in the range of175–185,225–250and300–340°C demonstrating that they have basic sites of different strengths:weak,moderate and strong.The total basicity was calculated according to the desorbed amount of CO2252G.Mitran et al.and summarized in Table1.The total basicity followed the order:Dy[Sm[Yb[Ce.TPR experiments have been carried out over all the mixed oxide samples prepared in order to study the redox properties of the catalysts.The TPR patterns of the catalysts are presented in Fig.5.All the samples displayed at high temperatures a large not well-deﬁned pattern which was decomposed in two reduction peaks.These peaks must correspond to the reduction of the tetravalent cation(Ce) according to the equation:Ce4??Ce3?,and to the reduction of trivalent Ln3?cations according to the equa-tion:Ln3??Ln2?.The low-temperature peak could be attributed to the reduction of the rare-earth cationic species from the rare-earth oxide clusters,and the high-temperature peak,attributed to the reduction of rare-earth cationic species in the large crystalline rare-earth oxide particles. We note that for Sm–Mg–Al–O sample a well-deﬁned low intensity peak was also observed before the large pattern.ItTable1Physico-chemical characteristics of the catalystsCatalyst SSA a(m2g-1)Chemical composition(%at.)by EDX bLn/(Ln?Mg?Al)atomic ratioMg/Al atomicratioTotal basicity(mmol CO2/g)Total H2consumption(mol H2/mol Ln)Ln Mg AlCe–Mg–Al–O157 1.721.17.2 5.6 2.9 1.630.13 Sm–Mg–Al–O160 1.826.07.1 5.2 3.6 2.180.12 Dy–Mg–Al–O102 1.521.37.0 5.1 3.1 2.520.18 Yb–Mg–Al–O142 1.925.3 6.5 5.6 3.9 1.960.19a Speciﬁc surface areab Oxygen in balancePropane Oxidative Dehydrogenation Over Ln–Mg–Al–O Catalysts253could be due to the reduction of the easily reducible samarium species from highly dispersed samarium oxide.These results suggest a non-uniform dispersion of the rare-earth oxide in the Mg–Al mixed oxide matrix.Assuming the reduction according to the equations above,0.5moles of H 2per mol of Ln would be necessary.The data from Table 1show that much lower quantities of H 2were experimentally consumed indicating that only a partial reduction of rare-earth cations occurred.3.2Catalytic Oxidative DehydrogenationFirstly blank tests have been done without a catalyst,the catalyst bed being replaced with quartz.Figure 6a shows that the non-catalytic oxidative conversion of propane is not signiﬁcant in our testing conditions,at least at tem-peratures below 600°C,conﬁrming that the contribution of the homogeneous reaction was negligible.The conversion of propane and the product selectivities as a function of reaction temperature for the reaction with propane–air mixtures at a total VHSV of 9,000h -1and a propane-to-oxygen molar ratio equal to 2,over the tested catalysts are depicted in Fig.6.For all the catalysts the conversion increased with increasing the reaction tempera-ture while the propene selectivity decreased to the beneﬁt of CO x for Ce-based system and of cracking products for the other systems.We note that the Yb-based system wasnot254G.Mitran et al.active at temperatures lower than500°C.For the reaction at 500°C the catalytic activity followed the order:Dy[ Sm C Ce[Yb.The differences in conversions indicate the inﬂuence of the metallic properties on the rate-determining hydrogen abstraction by the catalysts[14].In the case of Ce–Mg–Al–O system,the sum of the selectivities of CO x and CH4was not equal to that of ethylene,as was the case with the other systems,but much higher within all the range of temperatures studied.This suggests that for Ce-based system,total oxidation products(CO x)were formed not only from C1species resulting from the cracking of propane,but also by the direct oxidation of propane or by further oxidation of propene.This was not the case for Sm-,Dy and Yb–Mg–Al–O catalysts.The apparent activation energies(E act)corresponding to the propane transformation on the different catalysts have been calculated(Table2)from the Arrhenius plots pre-sented in Fig.7.The activation energies increased fol-lowing the order Dy\Sm B Ce\Yb,in line with the observed variation of the catalytic activity.On the other hand,the values obtained for the activation energies fall within the usual range measured for propane oxidative dehydrogenation over oxide-based catalysts[22,23].The effect of the conversion on the selectivities has been studied for the reactions over all Ln–Mg–Al–O catalysts at 550°C and a propane-to-oxygen molar ratio equal to2,by varying the VHSV in the range3,000–12,000h-1(Fig.8).Table2Apparent activation energies corresponding to the propane transformation on the Ln–Mg–Al–O catalystsCatalyst E act(kcal mol-1)Ce–Mg–Al–O23.7Sm–Mg–Al–O23.2Dy–Mg–Al–O19.0Yb–Mg–Al–O27.3Propane Oxidative Dehydrogenation Over Ln–Mg–Al–O Catalysts255As expected,the selectivity to propene decreased in all cases with increasing conversion.The extrapolation to zero conversion results,for the reaction over Ce-based system, in non-zero selectivity for carbon oxides and cracking products indicating that they are also primary products formed simultaneously with propene.For the reaction over other Ln-based systems studied,the extrapolation to zero conversion results in zero carbon oxides selectivity and non-zero selectivity for cracking products showing that only the latter are also primary products,carbon oxides being not in this case.These results conﬁrm that,among the catalysts studied,the parallel reaction of propane leading to carbon oxides is speciﬁc only for Ce-based system.On the other hand,the conversion-selectivity curves clearly showed that the oxidative dehydrogenation selec-tivity followed the order:Dy[Sm[Yb[Ce.The changes in the selectivities on the studied catalysts indicate the effect of Ln properties on the selectivity.The effect of the propane-to-air molar ratio on the oxi-dative dehydrogenation of propane over Dy-based catalyst is presented in Fig.9.The propane conversion strongly decreased when the propane-to-oxygen molar ratio increased from1to4.At the same time the selectivity to propene increased at the expense of cracking products and carbon oxides.These results could be explained by the decrease of the available oxygen related to the increase in the propane-to-oxygen ratio.Moreover,the observed decrease of the selectivity for cracking products can be explained taking into consideration that when the propane-to-oxygen molar ratio was increased keeping the total VHSV constant, the partial pressure of propane in the reaction mixture increased,cracking being thus disadvantaged.A linear correlation between the catalyst CO2-TPD basicity and the propene selectivity was observed as shown in Fig.10both for the reaction at500and550°C.The direct relationship found between surface basicity and propene selectivity can be accounted for by the electron-donating character of the oleﬁnic species and the conse-quent easier desorption from a more basic surface,thus preventing further overoxidation into carbon oxides. Interestingly,the most selective catalysts proved the most active as well(Fig.6).We note that the Mg–Al mixed oxide-supported rare-earth oxides studied in this work exhibit better performance in terms of selectivity to propene than the c-Al2O3-sup-ported rare-earth oxides in Ref.[14],conﬁrming the expected effect of magnesium.Finally,we note that no correlation between the H2-TPR reducibility of the rare-earth cation and the catalytic per-formances was observed,suggesting that the surface-adsorbed oxygen but not lattice oxygen species are involved in the reaction.A similar result was obtained by Al-Zahrani et al.[14]for c-Al2O3-supported rare-earth oxide catalysts by estimating the lattice oxygen reactivity from the reduction potential of the cation.256G.Mitran et al.4ConclusionsThe properties of basic Ln–Mg–Al mixed oxides catalysts for the ODH of propane have been investigated in the temperature range450–600°C.For all the catalysts the conversion increased with increasing the reaction temper-ature while the propene selectivity decreased.The best yields in propene were obtained with Dy-and Sm–Mg–Al–O systems,Dy-based catalyst being the most selective one. Increasing the propane-to-oxygen molar ratio from1to4 for Dy-based catalyst,the propane conversion decreased from8to2%but the propene selectivity increased from55 to75%at the expense of cracking products and carbon oxides.A linear correlation between the catalyst basicity and the propene selectivity was observed.On the other hand,no correlation between the H2-TPR reducibility of the rare-earth cation and the catalytic performances was observed.Acknowledgment This research was supported by the Romanian National University Research Council(CNCSIS)under the project ‘‘IDEI’’No.1906/2009.References1.D’Ippolito SA,Ban˜ares MA,Garcia Fierro JL,Pieck CL(2008)Catal Lett122:2522.Karakoulia SA,Triantafyllidis KS,Lemonidou AA(2008)MicroMeso Mater110:1573.Sugiyama S,Osaka T,Hirata Y,Sotowa KI(2006)Appl Catal A312:524.Dz´wigaj S,Gressel I,Grzybowska B,Samson K(2006)CatalToday114:2375.Koc SN,Gurdag G,Geissler S,Guraya M,Orbay M,Muhler M(2005)J Mol Catal A225:1976.Heracleous E,Machli M,Lemonidou AA,Vasalos IA(2005)JMol Catal A232:297.Ban˜ares MA,Khatib SJ(2004)Catal Today96:2518.Davies T,Taylor SH(2004)J Mol Catal A220:779.Zhaorigetu B,Li W,Xu H,Kieffer R(2004)Catal Lett94:12510.Wu Y,He Y,Chen T,Weng W,Wan H(2006)Appl Surf Sci252:522011.He Y,Wu Y,Chen T,Weng W,Wan H(2006)Catal Commun7:26812.Trionfetti C,Babich IV,Seshan K,Lefferts L(2006)Appl CatalA310:10513.Jibril BY(2005)Ind Eng Chem Res44:70214.Al-Zahrani SM,Jibril BY,Abasaeed AE(2003)Catal Lett85:5715.Buyevskaya OV,Wolf D,Baerns M(2000)Catal Today62:9116.Zhang W,Zhou X,Tang D,Wan H,Tsai K(1994)Catal Lett23:10317.Rives V,Ulibarri MA(1999)Coord Chem Rev181:6118.IUPAC Reporting physisorption data for gas/solid system(1985)Pure Appl Chem57:60319.Das J,Das D,Parida KM(2006)J Coll Int Sci301:56920.Tichit D,Das N,Coq B,Durand R(2002)Chem Mater14:153021.Parida KM,Das J(2000)J Mol Catal A Chem151:18522.Mattos ARJM,da Silva San Gil RA,Rocco MLM,Eon J-G(2002)J Mol Catal A178:22923.Male JL,Niessen HG,Bell AT,Tilley TD(2000)J Catal194:431Propane Oxidative Dehydrogenation Over Ln–Mg–Al–O Catalysts257。

_Al_2O_3载体研究进展_张李锋

3973前期预研专项(2004CCA04800)资助　张李锋:男,硕士研究生,主要从事催化剂载体研究　赵斌元:通讯联系人　E 2mail :byzhao @γ2Al 2O 3载体研究进展3张李锋1,石　悠1,赵斌元1,胡克鳌1,唐建国2(1　上海交通大学金属基复合材料国家重点实验室,上海200030;2　青岛大学化工学院,青岛266000) 摘要氧化铝催化剂载体领域中,γ2Al 2O 3应用最为广泛。

综述了γ2Al 2O 3载体的主要研究方向方面的进展:制备工艺低成本化、孔结构控制、提高载体稳定性和制备超细γ2Al 2O 3,并指出结合制备方法的改善,开发出大比表面积、适宜孔径分布及热稳定性和抗水合性良好的γ2Al 2O 3载体,同时发展纳米γ2Al 2O 3以满足实际生产的需要。

关键词 γ2氧化铝　载体　催化剂　孔结构Progress in R esearch on γ2Alumina C atalyst C arrierZHAN G Lifeng 1,S H I Y ou 1,ZHAO Binyuan 1,HU Keao 1,TAN G Jianguo 2(1　National Key Lab in Metal 2Matrix Composite ,Shanghai Jiaotong University ,Shanghai 200030;2　Institute of Chemical Technology ,Qingdao University ,Qingdao 266000)Abstract γ2alumina has been used most widely in the area of alumina catalyst carrier.In this paper ,the pro 2gress in the field of γ2alumina catalyst support is reviewed mainly as directions as follows :reducing the manufacturing cost ,controlling the pore ′s structure ,improving the stability of the carrier and preparing super 2fine γ2alumina.Further 2more ,it is also suggested that catalyst carriers including γ2Al 2O 3with larger specific surface area ,suitable pore size dis 2tribution ,excellent thermal stability and hydration resistibility ,and nano 2γ2Al 2O 3should be developed for the need ofindustry.K ey w ords γ2alumina ,catalyst carrier ,catalyst ,pore structure 0　引言氧化铝除用于冶炼金属铝外,在电子封装用衬底、磨料、结构材料、耐火材料、催化剂及其载体领域也得到广泛应用[1]。

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TiO2–Al2O3asasupportforpropanepartialoxidationoverRhVaidyanathanSubramanian,aJieunChoi,bE.G.Seebauer,candR.I.Maselc,*aDepartmentofChemicalEngineering,UniversityofNevada,LMR474,MS388,Reno,NV89557,USA

bPohangUniversityofScienceandTechnology,Pohang,SouthKorea

cRogerAdamsLaboratory,UniversityofIllinoisatUrbana–Champaign,MC-712,BoxC-3,600SouthMathews,Urbana,IL61801,USA

Received7August2006;Accepted26October2006

WeshowthatsupportspreparedbyadditionofTiO2toAl2O3improveshydrogenyieldfrompropanepartialoxidationby30%.AnoptimalhydrogenyieldisobtainedwithaTiO2–Al2O3compositeof0.54:0.46ratiodepositedwithRhoperatingat900°C.Long-termoperationshowsthatTiO2delayscatalystdeactivation,onlyupto25hrs.

KEYWORDS:propane;partialoxidation;TiO2;Al2O3;TiO2–Al2O3;rhodium;hydrogen.

1.IntroductionHydrogenproductionhasbeenthefocusofmuchresearchasapossiblealternativefuelsource[1,2].HydrogencanbeusedeﬀectivelyasafueltopowersystemsproducingenergyoverarangefrommW(por-tablesystems)toKW(onsitepowergeneration).Sev-eralreviewshavediscussedhydrogengenerationfromhydrocarbonsathightemperatures[3,4].Ageneralprocessforhydrogengenerationinvolveshydrocarbonoxidationoveracatalystdepositedonanoxidesupport.Oneexampleofsuchaprocessispropaneconversionbysteamreformingandpartialoxidationathightemper-atures[5].Partialoxidation(POx)ofpropaneisanexothermicprocessandoccursattemperaturesbetween500°Cand1000°C[6].Ingeneral,hightemperatureprocesssuchasPOxresultinproblemssuchascoking(ofsupport)andsintering(ofcatalyst)[7].Sincepre-ciousmetalsareusedasthecatalyst,eﬀortstominimizetheseproblemsarenecessary,asisthelong-termsta-bilityofthecatalystanditssupport.Sofar,propanePOxtoproducehydrogenhasbeenperformedoveroxidessuchasAl2O3[4–6,8,9].Ithas

beenfoundthatTiO2favorablyyieldsparticularlylowCOgeneration[10]andhigherselectivitytowardhydrogen[11].Mixedoxidesupportsinprinciplemaydisplaythebeneﬁcialpropertiesoftheparentoxides.Indeed,afewreportsdiscusstheapplicationofmixedoxidesassupportsforcatalyticconversionofpropane(oxidation[12],dehydrogenation[13]).Inanearlierreport,weshowedthatTiO2–Al2O3

mixedoxidespreparedbyasol–gelprocesscanbestable

upto900°C[14].NotransformationoftheTiO2phasefromanatasetorutileisobservedupto900°C,over

long-termexposure.ItisimportanttomaintaintheTiO2

inanatasephasebecauseitassistsinmaximizingand

retainingthedispersabilityofthemetalbydelayingthesinteringofthemetal.Thispromisingresult,ledustoexaminetheapplicabilityoftheTiO2–Al2O3mixed

oxideasasupportforthecatalyticpartialoxidationofpropaneoverRh.InthiscommunicationwehaveshownthatthepresenceofTiO2withAl2O3improvesthe

hydrogenyieldcomparedtousingAl2O3aloneasasupport,anddoessooverperiodsuptoatleast25hrs.Further,long-termstudiesshowthatRhdepositedonAl2O3leadstoarapiddecreaseinhydrogenyield,while

presenceofTiO2withAl2O3improvesthehydrogenyieldathightemperaturesunderotherwisesimilaroperatingconditions.

2.Experimental2.1.Tiitania–Alumina–Rhodiumcatalystsynthesisandcharacterization

TiO2waspreparedbythesol–gelmethodfroma

titaniumisopropoxideprecursor(Aldrich).Al2O3

(DegussaÒcorporation)wasaddedtotheTiO2solin

variousproportionstoobtainthemixedoxidesupport.Themixedoxideswereﬁredinairat900°Ctotrans-formthephasesfromamorphoustocrystalline.Syn-thesisdetailsofthemixedoxidesandtheirpropertiesaftercalcinationhavebeenelaboratedelsewhere[14].A$10mLsolutionofrhodiumchloride(Aldrich)inwater(1mgRhsalt/1mLofwater)waspreparedtoimpreg-natethemixedoxidepowder.Asmallamount(0.3mL)ofthesaltsolutionwasaddedto0.8gofmixedoxidepowder.Subsequently,2mLofdeionizedwaterwasadded,andthemixturewassonicatedtoensurehomo-geneity.Thewaterwasthenevaporatedbyslowdrying*Towhomcorrespondenceshouldbeaddressed.

E-mail:r-masel@uiuc.edu

CatalysisLettersVol.113,Nos.1–2,January2007(Ó2007)13DOI:10.1007/s10562-006-9006-4

1011-372X/07/0100–0013/0Ó2007SpringerScience+BusinessMedia,LLCat$80°Covernight.Theoxide–Rhmixturewasloadedontoaquartztubeandreducedat600°Cfor2hrina100sccmﬂowof8.5%hydrogen–91.5%Helium.HeliumﬂowwasalwaysmaintainedduringcoolingtokeepatmosphericoxygenfromcontactingthereducedRhuntilroomtemperaturewasreached.ChemisorptionmeasurementswereperformedbyaMicromeriticsÒsystem(PulseChemisorb2705)using

$200–300mgofthecatalyst-supportmixture.Beforethemeasurements,thesupport-catalystcompositewaspretreatedundera50:50N2–H2mixturefor2hrat

400°C,followedbycoolingtoroomtemperatureunderN2ﬂow.HydrogenwaspulsedintermittentlytotitratetheactiveRhsurface;andspeciﬁcmetalareawasesti-matedusingstandardexpressionsfoundelsewhere[15].ImageswereobtainedbyaPhilipsCM200transmissionelectronmicroscopy(TEM).