过渡金属氧化物负载对Nd2O3基催化剂同时去除NOx-炭烟活性的影响

利用程序升温反应技术（TPR）详细考察了负载K和不同过渡金属在Nd₂O₃ 基复合氧化物催化剂的催化活性，探讨了不同负载量对NOx－炭烟同时催化去除活性的影响。研究结果表明，负载Cr具有最好的炭烟催化活性，其最佳负载质量分数为10%；负载Mn具有最大的NOx→N₂转化率；复合晶相的生成提高NOx－炭烟同时催化去除活性。     

负载型La-K-Cu-Mn-O催化剂同时去除颗粒物和NOx性能

通过在柴油机排放颗粒物过滤器上负载La_0.8K_0.2Cu_0.05Mn_0.95O₃复合金属氧化物催化剂并进行实际柴油机尾气挂烟,利用程序升温反应技术,对同时催化去除柴油机颗粒物和氮氧化物反应进行了实验研究。研究结果表明,空白载体上实际柴油机排放颗粒物燃烧生成的CO₂曲线呈双峰,分别对应于可溶性有机物和干碳烟的燃烧。负载型催化剂能有效降低可溶性有机物和干碳烟的燃烧温度,促进NO向N₂转化。与淤浆法相比,浸渍法负载的催化剂效果更好,浸渍法负载催化剂可以将起燃温度降至160 ℃,最高的NOx向N₂转化率达63.4%。     

负载型铁基高温变换催化剂的制备和性能研究

分别以镁铝尖晶石和活性炭作为载体制备了负载型铁基高温变换催化剂，通过XRD、TEM和活性评价测试，考察了催化剂的结构和催化反应性能。以镁铝尖晶石负载γ-Fe₂O₃制得的催化剂，其催化活性明显高于负载α-Fe₂O₃催化剂，当催化剂组成为：Fe₂O₃ 26%，K2O 2%，MgO 0.05%，Cr₂O₃ 0.7%时，400℃下CO转化率为92%，350℃为84%（汽/气=1， 空速=2000 h^-1）；经氧化处理的活性炭作为催化剂载体时，低铬条件下也具有较好的催化活性，当负载量为40%时，相同变换反应条件下CO的转化率在400℃和350℃下分别为88%和80%。两种催化剂在低Cr₂O₃含量时都保持了与传统铁铬系变换催化剂(B117型)相当的催化活性，对于改善环境具有很大意义。     

糠醛加氢制糠醇中γ-Al2O3负载Cu-Zn催化剂的改性研究

采用浸渍法制备Co改性γ-Al₂O₃负载的Cu-Zn催化剂，考察Cu-Zn负载量、Co含量及反应温度等对催化剂性能的影响。结果表明，在413 K、氢气流速0.5 mL·s^－1 和糠醛空速2 h^-1 条件下,当催化剂Cu-Zn/γ-Al₂O₃（Co）中n(Cu)∶n(Zn)∶n(Al)∶n(Co)＝1.0∶2.0∶3.0∶0.51时，糠醇的选择性100％，糠醛转化率94.6％，比使用单纯Cu-Zn/γ-Al₂O₃催化剂的最佳转化率提高11％。     

γ-Al2O3负载铜锌氧化物催化剂的N2O催化分解性能

以γ-Al₂O₃为载体,采用共浸渍法合成了负载量为35%（以CuO与ZnO总质量计）的CuZn金属氧化物催化剂,分别考察了金属助剂（Co、Ni,、Mg、Fe、Mn、Ba和Ce）对催化剂的影响。采用XRD、BET和H₂-TPR等方法对制备的催化剂进行表征,在微反装置上对催化剂的N₂O催化分解活性进行评价。结果表明,合成的CuZn氧化物催化剂均具有CuxZn_1-xAl₂O₄的类Co₃O₄尖晶石结构;加入金属助剂使催化剂的比表面积不同程度得到提高,催化剂的N₂O催化分解反应活性不仅与Cu³⁺还原为Cu²⁺的温度有关,还与晶粒尺度大小和催化剂比表面积等有关;其中,含金属助剂Ni的催化剂具有相对较高的N2O催化分解反应活性,其N₂O完全转化温度为567 ℃。除含金属助剂Ba催化剂以外,加入其他金属助剂有利于N₂O催化分解反应进行。     

柴油车尾气四效组合催化剂的研究

提出设计双层组合催化剂净化新技术,即碳黑氧化燃烧催化剂床层和NOx还原催化剂床层的组合,该组合催化剂对柴油机尾气四种污染物的消除具有较高的催化活性。采用浸渍法制备了Al₂O₃负载不同量的La_0.8K_0.2MnO₃和相同负载量、不同K含量的La_1-xK_xMnO₃/Al₂O₃催化剂作为氧化催化剂处理碳烟、CO和HC;采用等体积浸渍法制备Cr/HZSM-5、Mo/HZSM-5、W/HZSM-5三系列催化剂作为还原催化剂处理NOx,并将其进行组合,得到优良的氧化还原组合催化剂,同时处理柴油车尾气中的四种污染物。在模拟柴油车尾气组成条件下,用乙炔代表烃类物质并采用固定床微型反应装置,考察了所制备的双层四效组合催化剂净化柴油车尾气的催化性能。研究发现,负载质量分数为50%的La_0.5K_0.5MnO₃/Al₂O₃和负载量为1.42×10^-4mol·g^-1的W/HZSM-5组合催化剂对于同时消除柴油车尾气NO、碳颗粒、CO和HC有较好的效果。NO还原为N₂的转化率在反应温度范围最高可达79%,同时碳颗粒的燃烧峰值温度为448 ℃,碳颗粒燃烧生成CO₂ 的最大选择性可达98%,乙炔完全转化的温度为364 ℃,从而实现了四种有害物质的同时催化净化。     

纳米MOx/ZrO2催化剂上乙醇氧化合成乙醛性能研究

采用溶胶-凝胶法首先制备出Zr(OH)₄凝胶，再将凝胶用乙醇进行醇化处理，经烘干和焙烧制得ZrO₂纳米载体。载体颗粒粒径均匀，大小为20 nm左右。以ZrO₂为载体，采用浸渍法分别负载Fe₂O₃、CuO、NiO和Mo₂O₃等不同金属氧化物，制得负载型催化剂。通过XRD、TEM、SEM和IR等对催化剂进行表征。以乙醇氧化脱氢合成乙醛为探针反应，考察了催化剂的催化性能。实验结果表明，催化剂Fe₂O₃/ZrO₂在反应温度为573 K时，乙醇转化率为75.8%，乙醛选择性为97.3%。     

制备条件对Cu/Al2O3 选择性催化还原NO的影响研究

考察了制备方法、活性组分负载量和焙烧温度对Cu/Al₂O₃ 选择性催化还原NO的影响。结果表明，采用溶胶-凝胶+浸渍法制备的Cu/Al₂O₃催化剂活性最好；负载Cu质量分数为15%时，催化剂的活性温域最宽，最大活性温度最低，催化活性最好；最佳焙烧温度为750 ℃。     

磷钼酸改性骨架铜催化剂上巴豆醛选择加氢制巴豆醇的研究

采用磷钼酸（H₃PMo₁₂O₄₀）对骨架铜催化剂（Raney Cu）进行改性,并以巴豆醛选择加氢反应为探针反应,考察了（H₃PMo₁₂O₄₀）负载量和焙烧温度对Raney Cu催化剂性能的影响。研究表明,随着H₃PMo₁₂O₄₀负载量的增加,催化剂对巴豆醇的选择性上升,当负载H₃PMo₁₂O₄₀质量分数达到7.2%时,催化剂对巴豆醇的选择性达到最高,为35.8%,而未改性的Raney Cu催化剂对巴豆醇的选择性只有0.32%。还考察了磷钼酸改性的骨架铜催化剂上巴豆醛选择加氢反应的工艺条件,研究表明,反应温度、反应压力和催化剂用量对巴豆醛的转化率有较大的影响,但对巴豆醇的选择性影响较小。适宜的反应条件为：H₂分压0.6 MPa,温度333 K,催化剂用量0.30～0.35 g·（mL-CRAL）^－1,此时巴豆醇的收率约25%。     

以稀土为助剂的负载型超细铁基变换催化剂的催化性能

以镁铝尖晶石为载体,稀土金属氧化物为助剂,吸附γ-Fe₂O₃胶体法制备了负载型铁系无铬变换催化剂。在负载变换催化剂上,活性组分Fe₃O₄以分立的超细微颗粒分布在镁铝尖晶石载体表面。添加镧、镨稀土金属氧化物明显改善了铁基负载型催化剂的催化活性。在汽/气＝1,空速为2 000 h^-1的反应条件下,镧改性负载型催化剂(FL/MA)的CO的转化率在400 ℃和350 ℃时分别为98%和80%。同时镧改性的负载型催化剂与B117催化剂相比,具有更好的耐热性,在高空速和低汽/气条件下也具有很好的催化活性。     

Fe2O3催化无烟煤燃烧燃点降低机理的实验研究

利用TG-DTG法和DTA法研究了无烟煤催化燃烧时燃点的变化情况,结果表明Fe2O3可使无烟煤的燃点降低。基于无烟煤燃点的形成原因和催化热解过程,研究了催化热解过程中热解转化率、热解气组成、半焦表面结构的变化情况,结果表明Fe2O3促进了无烟煤的热解,热解转化率、热解气的组成明显变化,热解气热值增加。催化热解产生的半焦表面形貌粗糙,颗粒细碎,比表面积大。由于热解过程直接影响到点燃过程,因此通过催化热解的研究,可知催化燃烧过程中均相燃烧（热解气燃烧）提供给异相燃烧（半焦燃烧）的热量高于非催化燃烧。同时催化热解所得半焦的吸附氧气能力强,在低温时吸附氧气的速率较快,缩短了达到点燃时所需氧气浓度的时间,进而降低了无烟煤的燃点。     

Effects of a Pt/Ce0.68Zr0.32O2 catalyst and NO2 on the kinetics of diesel soot oxidation from thermogravimetric analyses

In this study, the reactivity of well-characterized diesel soot samples is investigated by thermogravimetry under different kinds of oxidizing atmospheres (20% O₂ or 10% O₂ + 700 ppm NO₂) either under catalyzed or non-catalyzed conditions. Whatever the atmosphere used, the catalyst Pt/ceria-zirconia was able to lower significantly the ignition temperature of soot, but the catalytic effect was found to be more pronounced when the oxidation process was assisted by NOx. This is due mainly to the efficiency of both catalyst components (the noble metal and the OSC material) in recycling the NO released after attack of the soot by NO₂. By contrast, the NO₂ is of very limited use in the absence of catalyst under our experimental conditions. The global kinetic parameters representative of the carbonaceous matrix oxidation are determined using a methodological approach combining thermogravimetric experiments and non-linear multivariate regression. The kinetic parameters obtained are consistent both with the literature results and the postulated mechanistic pathways for soot oxidation assisted or not by NOx.     

Sn催化剂对柴油车排气颗粒去除效果

制备了以Sn为活性组分,以Cu、K、V为助催化剂,以TiO₂/γ-Al₂O₃/堇青石为载体的催化剂,催化剂在700℃下于空气中在马弗炉活化3h.采用DSC/TG测试方法确定催化剂的活性.研究发现,以Sn为活性组分的催化剂能显著降低颗粒的起燃温度和扩大燃烧温度范围,Cu、 K、V的添加能进一步降低起燃温度,而燃烧温度范围却稍有所变窄.活化会降低催化活性,活化导致活性下降的原因不是由催化剂的烧结引起的,而是由活性组分的挥发流失造成的.     

Global kinetic modelling of the reaction of soot with O2 and NOx on Fe2O3 catalyst

This study deals with the catalytic reaction of NO_x and soot on Fe₂O₃ to yield N₂ and CO₂ in excess of oxygen. Based on the three types of kinetic experiments, i.e. temperature programmed oxidation (TPO), transient examinations and gradient-free loop reactor experiments, as well as mechanistic studies presented recently a global kinetic model is established. The model includes catalytic effect of the iron oxide on soot/O₂ reaction, whereas it is assumed that NO_x reduction occurs on the soot without direct participation of Fe₂O₃. Furthermore, the model implies global kinetic expressions for the CO_x formation and NO_x reduction. These equations include the evolution of the surface area of soot and the correlation of reactive carbon sites (C_f) with those specifically involved in NO_x reduction (C*). The kinetic model is sequentially developed by accounting for the catalytic and non-catalytic soot/O₂ as well as soot/NO_x/O₂ conversion. Kinetic parameters are taken from the literature and are also determined from a fit to experimental data. Comparison of measured and calculated data shows accurate reproduction of the experiments and the model. Finally, the kinetic model is validated by some simulations.     

Simultaneous Catalytic Removal of Nitrogen Oxides and Soot from Diesel Exhaust Gas over Potassium Modified Iron Oxide

Iron oxide modified by potassium, i.e. Fe_1.9K_0.1O₃, exhibits high catalytic performance for the simultaneous conversion of soot and NO_x into CO₂ and N₂. The present study shows that long‐time treatment of the catalyst leads to a drastic decrease in the activity, whereas even the aged catalyst maintains considerable activity. On the other hand, long‐time treatment causes selective N₂ formation, i.e. no more formation of the byproduct N₂O. This alteration of catalytic performance is likely due to agglomeration of the promoter potassium being present at the surface of catalyst. Detailed experiments were carried out with a more realistic diesel model exhaust gas to confirm that Fe_1.9K_0.1O₃ is a suitable catalyst for the simultaneous removal of soot and NO_x between 350 and 480 °C. It was assumed that (CO) intermediates, formed by the catalytic reaction of NO_x and oxygen with the soot surface, are the reactive species in NO_x‐soot conversion.     

过渡金属氧化物对烟火药剂的催化作用

为了提高含高氯酸钾和硝酸钾烟火药剂的反应速率,应用混合法和结晶法将过渡金属氧化物（TMO）氧化铁添加到含高氯酸钾的烟火药剂中,将氧化铜添加到含硝酸钾的烟火药剂中。利用绝热加速量热仪（ARC）分别研究了氧化铁对含高氯酸钾烟火药剂、氧化铜对含硝酸钾烟火药剂的催化作用。结果表明,氧化铁对含高氯酸钾的烟火药剂具有催化作用,以结晶添加法催化效果最佳;此药剂的最大反应速率为8.10 min^-1,是不含催化剂药剂的4.09倍;到达最大反应速率时间为8.52 min,比不含催化剂的药剂降低了92.8%。氧化铜对含硝酸钾的烟火药剂具有催化作用,混合法添加的催化效果最佳;此药剂最大反应速率为7.38 min^-1,是不含催化剂药剂的1.30倍;到达最大反应速率时间为53.55 min,比不含催化剂的药剂降低了66.3%。     

A highly efficient and porous catalyst for simultaneous removal of NOx and diesel soot

A highly efficient and porous catalyst (La_0.8K_0.2Cu_0.05Mn_0.95O₃) for simultaneous removal of nitrogen oxides (NOx) and diesel soot was synthesized and the sample was characterized by XRD, BET, SEM–EDS, XRF, and XPS. The results indicate that this catalyst is perovskite and it possesses the very good characteristics for multiphase catalytic reactions. The catalytic properties were appraised under simulated diesel engine exhaust by temperature programmed reaction (TPR). TPR results indicate that this catalyst is a promising candidate for simultaneous removal of NOx and diesel soot. The maximum NO conversion into N₂ and the ignition temperature of soot are 54.8% and 260 °C, respectively. Comparing with those in previous reports, the comprehensive performance of this catalyst is greatly improved by partial substitution of La with K and Mn with Cu at the same time.     

固体氧化物质子传导膜H2S燃料电池

引　言H2 S固体氧化物燃料电池首先由美国学者Pujare等[1] 于 1987年提出 ,它是以废气中的H2 S作为燃料 ,固体氧化物YSZ (氧离子传导 )为离子传导膜 ,由于在脱除H2 S的同时可获得绿色能源———电能 ,引起了学术界与工业界的极大关注 .GeorgiaInstituteofTechnology的Yates等、     

CoAl2O4 spinel catalyst for soot combustion with NOx/O2

Mesoporous and nanosized cobalt aluminate spinel with high specific surface area was prepared using microwave assisted glycothermal method and used as soot combustion catalyst in a NO_x + O₂ stream. For comparison, zinc aluminate spinel and alumina supported platinum catalysts were prepared and tested. All samples were characterised using XRD, (HR)TEM, N₂ adsorption–desorption measurements. The CoAl₂O₄ spinel was able to oxidise soot as fast as the reference Pt/Al₂O₃ catalyst. Its catalytic activity can be attributed to a high NO_x chemisorption on the surface of this spinel, which leads to the fast oxidation of NO to NO₂.     

NO与Co(NH3)2+6气液反应动力学

用Co(NH₃)²⁺₆的氨水溶液可同时实现NO的氧化和吸收过程.NO 与Co(NH₃)²⁺₆气液反应动力学研究表明，NO与Co(NH₃)²⁺₆的反应为瞬间反应，当Co(NH₃)²⁺₆浓度低于20mmol•L^-1时过程为双膜控制，当Co(NH₃)²⁺₆浓度大于20mmol•L^-1时过程逐渐变为气膜控制.NO的吸收速度随温度的升高而降低，气相中氧的存在有利于NO的吸收，但当氧的含量高于5.2%后再继续增加氧的含量NO吸收速率提高不大.经研究建立了有氧时NO 与Co(NH₃)²⁺₆气液反应动力学方程.