Pd/ZSM-5/堇青石整体式催化剂对甲苯的催化降解性能研究

以蜂窝状堇青石为载体,采用聚乙烯醇(PVA)溶液辅助涂覆法制备Pd/ZSM-5/堇青石整体式催化剂,利用XRD、N2吸附-脱附、SEM等方法对催化剂结构和性质进行表征。通过气相色谱分析催化剂对甲苯降解效果,考察了Pd的质量分数、堇青石煅烧时间及浆料涂覆次数对催化降解甲苯性能的影响。结果表明,ZSM-5分子筛具有较大比表面积,能有效负载Pd,在粘结剂的作用下与堇青石载体有效结合;制备的5%Pd/ZSM-5/堇青石对甲苯的催化降解效果最好,T_(50)和T_(90)分别为275℃和313℃;堇青石焙烧时间4 h的催化效果最好;负载5%Pd质量分数的分子筛对堇青石涂覆6次时性能最优,制备的Pd/ZSM-5/堇青石整体式催化剂显示出良好的催化氧化甲苯活性。     

铜系催化剂选择性催化还原脱除NOx研究

以硅胶改性堇青石蜂窝陶瓷为载体,分别制备了以Cu-O、Cu-Ce-O和Cu-Ce-Mn-O为活性组分的催化剂。以CO(NH₂)₂为还原剂,在固定床反应器中进行选择性催化还原NO的研究。采用XRD、SEM和BET等测试方法对催化剂进行表征。结果表明,在温度(300～500) ℃,催化剂Cu-Ce-Mn-O/SiO₂/堇青石的活性优于催化剂Cu-O/SiO₂/堇青石和Cu-Ce-O/SiO₂/堇青石,反应温度为450 ℃、空速为8 000 h^-1时,Cu-Ce-Mn-O/SiO₂/堇青石催化剂催化还原NO的转化率可达到88%。     

活性组分负载量对CuO-CeO_2/Cord.整体式催化剂性能的影响

蜂窝状的堇青石载体经20%的草酸溶液沸煮预处理后,采用共浸渍法制备了CuO-CeO2/Cord.整体式催化剂,分别考察了不同活性组分CuO-CeO2负载量对催化剂性能的影响,并运用X射线衍射(XRD)、程序升温还原技术(TPR)对样品进行了表征。测试结果表明不同的活性组分负载量对催化剂性能均有一定影响,当CuO-CeO2负载量为15%时催化剂表现出了最好的活性和选择性。     

蜂窝状Fe-Mo/ZSM-5催化剂制备及其对NOx催化还原性能的影响

以具有较低热膨胀系数和较好抗热冲击性的堇青石蜂窝状陶瓷为载体、Fe-Mo/ZSM-5为活性组分制备了蜂窝状催化剂,研究了表面活性剂、载体和涂覆方法等条件对蜂窝状催化剂性能及其催化活性的影响。采用XRD、FT-IR、BET和SEM等技术对蜂窝状催化剂的体相结构、表面离子形态等进行了表征和研究。结果表明,以羧甲基纤维素为表面活性剂、美国康宁公司的堇青石蜂窝状陶瓷为载体和超声波法涂覆的蜂窝状催化剂具有最佳的催化活性,300 ℃时NOx催化转化率达100%,且随着温度的升高保持不变。     

贵金属催化燃烧催化剂的研究

VOCs大多具有毒性,并伴有刺激性的恶臭,直接排放会威胁人类健康,并对环境造成严重污染。目前,催化燃烧技术是工艺较为成熟,同时也是应用较为广泛的VOCs的净化方法。实际过程使用的催化燃烧催化剂多为具有规整结构的蜂窝状催化剂,活性组分通常为Pt、Pd、Ru等贵金属。从整体式催化剂的角度出发,制备了Al_2O_3和TiO_2两种涂层的整体式催化剂用于催化燃烧消除苯的实验,未添加铈锆粉时的活性顺序:Pt/Al_2O_3/堇青石Pt/TiO_2/堇青石;添加铈锆粉后的活性顺序:Pt/CZ-Al_2O_3/堇青石Pt/CZ-TiO_2/堇青石,同时铈锆粉的添加还可以提高催化剂的热稳定性。     

原位水热合成法制备ZSM-5/堇青石整体式催化剂

以蜂窝状堇青石为载体,采用原位水热合成法制备了ZSM-5/堇青石整体式催化剂。考察了四丙基氢氧化铵(TPAOH)含量、水硅摩尔比和晶化温度等对ZSM-5分子筛在堇青石载体上负载量的影响。结果表明:模板剂TPAOH的含量对负载量有显著影响,当摩尔比n(TPAOH)/n(SiO2)≤0.2时,改变晶化温度和水硅摩尔比均可获得较佳的分子筛负载量;当n(TPAOH)/n(Si O2)0.2时,较高的碱度导致前驱体溶胶的溶解,使分子筛多在溶液中晶化,显著减小分子筛在堇青石载体上的负载量。当n(TPAOH)/n(Si O2)≤0.2时,水硅比减小,ZSM-5分子筛负载量逐渐增大,最大负载量可达42.8%。晶化温度降低,分子筛的负载量和晶粒均减小。整体式催化剂用于NO的催化氧化活性研究表明,堇青石载体上分子筛的负载量越高,整体式催化剂的比表面积越大,催化活性越好。     

La-Ni2P/SBA-15/堇青石整体式催化剂及加氢脱硫性能

以介孔分子筛SBA-15为载体,制备一系列不同La含量的La-Ni₂P/SBA-15催化剂前驱体,将La-Ni₂P/SBA-15前驱体涂覆在预处理的整体式载体堇青石上,在H2气氛程序升温还原,制备不同La含量的La-Ni2P/SBA-15/堇青石整体式催化剂。对合成的催化剂进行X射线衍射和N2吸附-脱附结构表征,并评价对二苯并噻吩的加氢脱硫活性。结果表明,Ni₂P存在于所有的La-Ni2P/SBA-15/堇青石整体式催化剂中,且随着La含量的增加,La-Ni2P/SBA-15/堇青石整体式催化剂的比表面积和孔体积均有一定程度的提高,催化活性也提高。对于Ni2P/SBA-15/堇青石整体式催化剂,在300 ℃和380 ℃时,二苯并噻吩加氢脱硫转化率仅为27.2%和91.3%;而1.5%La-Ni₂P/SBA-15/堇青石催化剂在300 ℃和380 ℃时,二苯并噻吩转化率分别为36.8%和96.3%,显示出较好的二苯并噻吩加氢脱硫活性。La-Ni₂P/SBA-15/堇青石整体式催化剂在对二苯并噻吩的加氢脱硫过程中,以直接脱硫和加氢脱硫两种脱硫方式同时进行,并且以直接脱硫为主。     

蜂窝陶瓷负载锰酸锶镧基催化剂制备及性能

采用不同浓度硝酸和草酸溶液,对堇青石蜂窝陶瓷载体进行预处理,考察了酸处理对载体失重率、吸水率及压缩强度的影响。采用催化剂粉体浆料涂覆法,制备了堇青石蜂窝陶瓷负载锰酸锶镧基La0.8Sr0.2Mn0.4Al0.4Zn0.2O3-δ(LSMAZ)整体式催化剂,运用X射线衍射(XRD)、扫描电镜(SEM)等手段对催化剂进行表征,并在管式反应器上进行甲烷催化燃烧活性测试。结果表明,酸处理能增大载体比表面积和吸水率;相同条件下草酸对载体的侵蚀效果优于硝酸;提高草酸浓度能增强侵蚀效果,但过高浓度的酸处理会使载体压缩强度过小而无法应用。经1050℃煅烧5 h后,所制备的整体式催化剂具有适宜的脱落率,无明显载体-LSAMZ界面反应,并具有最高的甲烷燃烧催化活性。     

堇青石载体预处理对蜂窝状催化剂的影响

使用不同酸、碱溶液对堇青石蜂窝陶瓷载体进行了预处理,考察了载体酸、碱预处理对蜂窝状Fe-Mo/ZSM-5催化剂涂覆率及NO_x催化还原性能的影响,并采用XRD,NH_3-TPD和扫描电镜等技术对蜂窝状催化剂表面形貌、结构特征和表面酸性进行了分析.结果表明,载体经酸性和碱性溶液预处理后,蜂窝状催化剂的涂覆率和催化能力都提高,且酸溶液预处理的效果要优于碱溶液预处理.分析认为,这与酸溶液作用下堇青石结构受到一定程度的破坏,表面变得粗糙以及所制备的蜂窝状催化剂表面较多的弱酸位有关.     

Pt-Pd/Ce_xZr_(1-x)O/SiO_2-Al_2O_3催化剂上丙烷催化氧化反应研究

以蜂窝状堇青石为载体,采用改性氧化铝浆液涂覆载体,再负载活性组分Pt和Pd,制备了丙烷催化燃烧催化剂,优化了催化剂制备工艺条件。研究表明:Si与CexZr1-xO的添加明显提高了涂层的耐高温性能,CexZr1-xO/SiO2-Al2O3涂层在高温下保持了较高的比表面积;活性组分Pt和Pd在其表面分散均匀;本实验制备的催化剂在430℃和20 000 h-1空速条件下,对含丙烷废气的总烃去除率可以达到90%以上。     

整体构件型La_(0.8)Sr_(0.2)MnO_3催化剂的制备和催化燃烧特性

为了解不同整体构件钙钛矿催化剂的VOCs催化燃烧特性,以不锈钢316L丝网和堇青石蜂窝陶瓷为基材,通过电泳沉积和浸涂技术在基材表面均匀涂覆γ-Al_2O_3粘合层,再在涂层表面负载钙钛矿型2.0%(wt)的La_(0.8)Sr_(0.2)MnO_3活性组分.SEM表征发现100 nm左右的La_(0.8)Sr_(0.2)MnO_3颗粒可以均匀、牢固地分散在不锈钢丝网和蜂窝陶瓷表面,经过550℃焙烧后无龟裂现象.超声振荡30 min后,活性组分损失率均小于5.0%(wt).甲苯催化燃烧测试表明,金属丝网型、蜂窝陶瓷型和颗粒型La_(0.8)Sr_(0.2)MnO_3催化剂表现出相似的催化性能,但金属丝网具有更好的传质效果和热响应速率,更适合处理高空速、温度和浓度波动较大的有机废气.     

Baeyer–Villiger oxidation of cyclohexanone catalyzed by cordierite honeycomb washcoated with Mg–Sn–W composite oxides

In this work, a series of Mg–Sn–W oxide powder catalysts with different tungsten oxide contents(0, 15 wt% and 30 wt%) were prepared and washcoated on cordierite honeycomb monoliths to produce monolithic catalysts,which were tested for the Baeyer–Villiger oxidation of cyclohexanone. The obtained monolithic catalysts,which combined the advantages of both homogeneous and heterogeneous catalysts, showed high catalytic efficiency and overcame the problems of product separation that occurred in the homogeneous catalytic process.SEM and EDX tests showed that the catalytic coating, with a thickness of approximately 20 μm, was compact and homogeneous, and an enlarged BET surface area was indicated by N_2 adsorption–desorption compared with the bare cordierite honeycomb. The chemical properties on the catalytic surface of the powder and monolithic catalysts were characterized by XPS, which indicated the tin and tungsten on the catalysts exhibited their full oxide states and presented mainly as stannate and tungstate, as confirmed by XRD and FTIR characterizations.Moreover, the catalytic activity test indicated that the tungsten content of the catalysts played an important role in catalytic efficiency and that monolithic catalysts were produced without obvious catalytic activity loss compared with the corresponding powders.(M)W30, which exhibited excellent mechanical stability and maintained high activity after recycling three times, was the optimal catalyst, showing a high selectivity that exceeded 86%and a conversion above 64%. Therefore, the structured Mg–Sn–W oxide catalysts have great potential for application in practical production.     

用于丙烷催化燃烧的PdxPty-ZSM-5/Cordierite整体式催化剂

以ZSM-5分子筛、铝溶胶、硝酸钯、硝酸铂和水为原料制备分子筛浆料，采用真空抽提-一次涂覆法在堇青石蜂窝陶瓷载体表面制备出Pd_xPt_y-ZSM-5/Cordierite整体式催化剂，考察了Pd负载量、ZSM-5分子筛的硅铝比和Pd/Pt质量比对整体式催化剂的丙烷催化燃烧性能的影响，并用超声波振荡、SEM、XRD、H₂-TPR和C₃H₈-TPD等手段对整体式催化剂进行了表征。当球磨时间为60 min，分子筛浆料固含量为38%时，整体式催化剂的涂层上载量可达到178 g?L^-1，涂层脱落率低于0.5%。Pd₂Pt₃-ZSM-5/Cordierite整体式催化剂（贵金属总负载量为1.2 g?L^-1）对于丙烷的催化燃烧具有较好的催化活性（T₅₀=259℃，T₉₀=323℃）和稳定性，具有良好的工业应用前景，其中较低的ZSM-5分子筛硅铝比以及Pd和Pt之间的相互作用增加了对丙烷的吸附能力和表面活性氧物种的数量，从而提高了整体式催化剂的催化活性。     

Catalytic performance of a novel ceramic-supported vanadium oxide catalyst for NO reduction with NH3

A novel TiO₂/Al₂O₃/cordierite honeycomb-supported V₂O₅–MoO₃–WO₃ monolithic catalyst was studied for the selective reduction of NO with NH₃. The effects of reaction temperature, space velocity, NH₃/NO ratio and oxygen content on SCR activity were evaluated. Two other V₂O₅–MoO₃–WO₃ monolithic catalysts supported on Al₂O₃/cordierite honeycomb or TiO₂/cordierite honeycomb support, two types of pellet catalysts supported on TiO₂/Al₂O₃ or Al₂O₃, as well as three types of pellet catalysts V₂O₅–MoO₃–WO₃–Al₂O₃ and V₂O₅–MoO₃–WO₃–TiO₂ were tested for comparison. The experiment results show that this catalyst has a higher catalytic activity for SCR with comparison to others. The results of characterization show, the preparation method of this catalyst can give rise to a higher BET surface area and pore volume, which is strongly related with the highly active performance of this catalyst. At the same time, the function of the combined carrier of TiO₂/Al₂O₃ cannot be excluded.     

Ni、Pt对柴油车排气颗粒物去除催化剂的修饰作用

以改性整体式堇青石蜂窝陶瓷为载体,用Ni和Pt修饰Cu-K-V/TiO₂/γ-Al₂O₃ /cordierite催化剂,制备了用于消除柴油车排气颗粒物的催化剂;采用DSC/TG方法确定催化剂的活性及BET、TG-IR等方法对催化剂进行了表征,探讨了Ni和Pt对Cu-K-V/TiO₂/γ-Al₂O₃ /cordierite催化剂的修饰作用及老化对催化剂的影响.研究发现经Ni和Pt修饰后的催化剂能有效降低柴油车排气颗粒物的最大燃烧速率时的温度,特别是对颗粒物中最难燃烧的石墨化部分的去除;而且Ni和Pt的添加能提高颗粒物的去除效率.对含Pt催化剂,老化会降低催化剂的活性;而对含Ni的催化剂,老化使催化剂的活性增加,这可能是Ni向催化剂非孔道的外表面迁移的结果.     

改性铝土矿负载Ni-Mn-K一氧化碳高温变换催化剂的研究

以改性后铝土矿石为载体,采用两步浸渍法,制备Ni-Mn-K一氧化碳高温变换催化剂。采用活性评价、低温N₂吸附、XRD和TPR等表征方法,考察催化剂的结构和性能。结果表明,改性后的铝土矿本身具有一定的变换活性,用该载体负载多组分制得的催化剂具有较好的变换活性。XRD和TPR结果表明,催化剂中具有明显的晶相NiO和K₂CO₃的特征衍射峰, MnO₂与铝土矿载体中的Fe₃O₂和SiO₂形成非晶态复合氧化物。比表面积和孔容减小主要因负载引起,负载活性组分后使耗氢量增大,还原峰温降低。     

前驱体溶液中Fe2+与Fe3+物质的量比对Au/α-Fe2O3催化剂低温水煤气变换性能的影响

改变前驱体溶液中Fe<'2+>与Fe<'3+>物质的量比制备了系列Au/α-Fe<,2>O<,3>水煤气变换催化剂,并运用XRD、拉曼光谱和H<,2>-TPR对样品进行表征.结果表明,Fe<'2+>与Fe<'3+>物质的量比的变化对Au/α-Fe<,2>O<,3>催化剂低温水煤气变换活性具有显著影响,这是由Fe<'2+...     

Selective catalytic reduction of nitrogen oxides from exhaust of lean burn engine over in situ synthesized monolithic Cu–TS-1/cordierite

Titanium silicalite (TS-1) zeolite was in situ synthesized successfully on the surface of honeycomb cordierite substrate, which was certified by XRD and SEM techniques. The in situ synthesized monolithic TS-1/cordierite showed superior thermal and hydrothermal stabilities. Cu–TS-1/cordierite prepared with ion-exchange and impregnation methods were studied as catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NO_x). For practicality, the evaluation experiments were carried out in exhaust of a real lean burn engine without any other additive. Cu–TS-1/cordierite prepared with two methods both exhibited similar high activities, and at about 715 K, the max NO_x conversion could reach 58% in the space velocity (SV) of 12000 h⁻¹. Ion-exchanged Cu–TS-1/cordierite had superior duration and anti-poison properties while impregnated Cu–TS-1/cordierite not. Cooper is the main active component in the catalyst and Cu(I), which was found in the catalyst during the proceeding of reaction by XPS, is thought to be essential.     

制备方法对高CuO含量的Cuo/CeO_2催化剂水煤气变换性能的影响

采用机械混合法、固相合成法、水热法、沉积-沉淀法和共沉淀法制备系列CuO/CeO_2水煤气变换催化剂,采用XRD、N_2物理吸附和H_2-TPR等方法对样品进行表征,研究制备方法对CuO/CeO_2催化剂结构的影响以及催化剂结构与其催化性能的关系。结果表明,共沉淀法有利于获得较小的CuO和CeO_2晶粒、较大的比表面积、孔容和孔径以及较好的还原性能,制得的催化剂活性和稳定性较好。