活性炭表面性质对Pd/C常温氧化CO的影响

采用等体积浸渍法制备了活性炭负载Pd催化剂(Pd/C),通过正交实验研究了活性炭的种类、催化剂的制备条件等对活性炭负载钯催化剂上CO氧化性能的影响,得到了最优的制备条件。并通过N2吸附、程序升温脱附(TPD)、程序升温还原(H2-TPR)和透射电镜(TEM)等对催化剂进行了表征。正交实验极差分析表明制备各因素对催化剂氧化CO活性影响的次序为:还原剂>活性炭>还原剂用量>还原温度>还原溶pH值。催化剂表征结果表明活性炭的比表面积和孔径分布不是决定Pd/C催化剂性能的关键因素,活性炭的种类、表面组成和性质对催化剂的性能有显著的影响。其中椰壳炭(AC1)表面羧基的活性较高,同时具有较强的表面碱性,有利于活性金属Pd在载体表面的分散,并提高了Pd与载体之间的相互作用,从而使催化剂具有较高的CO氧化性能。提高Pd的担载量,可显著提高催化剂稳定性。以乙二醇作为还原剂,在pH=10,还原温度为60℃的条件下所制备的0.5%Pd/AC催化剂,在反应温度20℃时连续反应120 h仍可保持CO的全转化。     

电感耦合等离子体原子发射光谱法测定废钯炭催化剂中钯

在聚四氟乙烯内衬压力消解罐中,180 ℃的温度下,采用王水消解烘干的废钯炭催化剂样品,建立了电感耦合等离子体原子发射光谱法(ICP-AES)测定废钯炭催化剂中钯的方法。考察溶样方法、消解时间、消解温度和干扰离子对测定的影响。结果表明:废钯炭催化剂先做烘干处理,在180 ℃温度下消解6 h,效果最佳;废钯炭催化剂中存在的Si、Al、Fe、Mg、Ca等元素对钯的测定无影响;钯浓度在0～250 mg/L范围内与强度呈线性关系,加标回收率为99.6%～100.5%,相对标准偏差小于1%。用实验方法与原子吸收光谱法测定同一个废钯炭催化剂样品,两者测定结果基本相符,方法适合废钯炭催化剂中钯的测定。     

新型C/C复合材料基体前驱体-COPNA树脂

以苯甲醛为交联剂, 萘为单体, 在浓硫酸催化下, 反应得到未交联的缩合多核芳香烃（COPNA）树脂. 采用红外光谱, 差热/热重分析仪等, 对COPNA树脂的合成反应及COPNA树脂的热稳定性进行了分析. 用合成的COPNA树脂对T300 6K炭布缠绕的坯体进行浸渍增密制备出了COPNA基炭/炭复合材料制品, 在常压浸渍固化炭化的条件下, 其残炭率达到53.15%. 研究结果表明： 优化单体与交联剂的物质的量比及催化剂的用量, 残炭率还有上升的空间, 显示出COPNA树脂是一种极具前景的新型C/C复合材料基体前驱体.     

稀土负载生物炭的制备及其对低浓度氨氮的吸附特性

对微波/稀土元素铈吸附剂的制备条件及其吸附降解低浓度氨氮的反应条件进行优化,并采用XRD、SEM和FTIR对负载型吸附剂进行了表征。实验结果表明,负载型吸附剂内部结构发生变化,比表面积增大,羟基数量增多;负载后的生物炭对氨氮的处理效果明显优于原生物炭,其较为合适的制备条件为固液比(指原生物炭质量与氯化亚铈溶液体积之比,单位g/mL)1:25,浸渍pH 10;在氨氮溶液浓度为50 mg/L,初始pH为10,反应温度为50℃,反应时间为120 min,吸附剂投加量为5 g/L条件下,氨氮吸附量达到最大,为11.297 mg/g,且反应过程符合准二级动力学模型。      

Rh/C催化剂的制备及其催化性能研究

以RhCl3.3H2O为前驱体,活性炭为载体,采用浸渍法制备了Rh/C催化剂,并使用场发射透射电镜对催化剂进行了表征。同时考察了制备条件对Rh/C催化剂在6-羟基-3,4-二氢异喹啉-2-甲酸甲酯-3-甲酸乙酯加氢反应中催化性能的影响。     

二氯化钯的制备与表征

针对传统二氯化钯生产工艺对原料纯度要求高、生产周期长、钯损失率高、反应终点不易控制等问题,创新提出采用二氯二氨合钯为原料,在比较温和的反应条件下制备了二氯化钯,所得产品中钯含量高达59.79%,并采用了化学分析法、X射线粉末衍射仪和电子扫描电镜对产品成分和形貌进行了分析与表征。     

负载型钒取代磷钼杂多酸的制备方法及应用

本发明是一种负载型钒取代磷钼杂多酸、制备方法及其应用。目前普遍使用的醛类气体消除方法是在室内空气中喷洒甲醛清除剂或甲醛捕捉剂通过吸附去除，其只能对游离甲醛有清除作用，无法对从人造板材、油漆、涂料中缓慢释放出来的甲醛清除长期有效。本发明以工业化生产的多孔硅胶或活性炭为载体、以磷钼钒杂多酸为活性组分通过浸渍法制备得到固体催化剂,该催化剂在常温常压条件下对甲醛的氧化反应具有催化活性，     

载体粒度对钯炭催化剂催化活性的影响

利用钯炭催化剂的苯甲酸加氢反应,考察了活性炭载体粒度(<44μm、44~74μm、74~150μm、>150μm对钯炭催化剂催化活性的影响。采用粒度分析法、BET和SEM对其进行表征,并利用加氢反应釜对其催化剂活性进行评价。结果表明:载体粒度>74μm,金属钯负载不均匀,导致催化剂活性下降;载体粒度<44μm,催化剂不易过滤,洗涤过程活性组分容易脱附,导致催化剂活性降低;载体粒度为44~74μm时,催化剂活性最高。     

制备四氯合钯酸铵的工艺研究

本文研究了四氯二氨合钯的制备方法,并探索了不同反应条件下四氯二氨合钯的产品纯度。确定了最佳制备条件。     

稀土固体超强酸S2O82-/Sb2O3/La3+的制备及催化性能研究

以SbCl3为原料经醇化水解制得Sb2O3前体氧化物,通过浸渍一定量的(NH4)2S2O8和掺杂La(NO3)3制备了一种新型催化剂S2O82-/Sb2O3/La3+.以催化合成乙酸苄酯为探针反应,考察了不同制备条件对催化剂性能的影响.结果表明,1.5 mol/L的(NH4)2S2O8和2.71% La(NO3)3混合溶液浸渍锑前体氧化物,经110℃烘干后,于500℃焙烧3h所得催化剂(SSL2.71-3-500)活性较好.同时,考察了催化剂的稳定性以及对不同酯化反应的作用规律.用Hammett,IR,DTA/TGA,XRD等手段对催化剂进行了表征.     

担载双金属催化剂对Heck反应的作用

制备了0．5％Pd／C催化剂和含钯担载双金属催化剂3％Cu．0．5％Pd／C，3％Mo-0．5％Pd／C，3％Ni-0．5％Pd／C，3％Co-0．5％Pd／C．3％Mn-0．5％Pd／C，用XRD法和XPS法进行了表征。结果表明，室温下，以KBH4还原剂制备的含钯担载双金属催化剂，在碘苯与丙烯酸的Heck偶合反应中，催化活性高于Pd／C（0．5h的转化率高，完成反应所需时问少），显示出添加贱金属的协同效应。其中，3％Mo-0．5％Pd／C显示出最高的催化活性，在0．5h时的转化率（67．4％）和收率（52．6％）比0．5％Pd／C分别高54．5％和42．2％，完成反应的时问最短，表明钼的协同效应最高。     

Palladium catalysts supported on novel CexY1-xO washcoats for toluene catalytic combustion

Novel CexY1-xO washcoats adhered on the cordierite honeycomb, used as supports for Pd catalysts, were prepared by an impregnation method. It was fotmd that the CexY1-xO washcoats had better adhesion and higher adsorption efficiency of H2PdCl4, and the optimal component of the washcoat was Ce0.8Y0.2O. Model reaction of catalytic combustion of toluene was chosen to evaluate the performance of the developed Pd/CexY1-xO/substrate catalysts. The results showed that the catalytic performance of the Pd/CexY1-xO/substrate catalysts depended on the component of the washcoats, with the Pd/Ce0.8Y0.2O/substrate catalyst giving the best catalytic activity and thermal stability.     

Fabrication of a flower-like Pd/CeO2 material with improved three-way catalytic performance

Pd/CeO2 catalysts with flower-like morphology were fabricated via an ultrasonic-assisted membrane reduction (UAMR) and hydrothermal methods. The catalysts were physically characterized and evaluated fo...     

Effect of cerium oxide prepared under different hydrothermal time on electrocatalytic performance of Pt-based anode catalysts

In this paper,CeO_2 with a pore size of 2-4 nm was synthesized by hydrothermal method.The CeO_2 modified graphene-supported Pt catalyst was prepared by the microwave-assisted ethylene glycol reduction chloroplatinic acid method,and the effect of the addition of CeO_2 prepared by different hydrothermal reaction time on the catalytic performance of Pt-based catalysts was investigated.The microstructures of CeO_2 and catalysts were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),specific surface area and pore size analyzer(BET),scanning electron microscopy(SEM) and electron spectroscopy(EDAX),transmission electron microscopy(TEM),and the catalysts electrochemical performance was tested by electrochemical workstation.The results show that the catalytic performance of the four catalysts with CeO_2 is better than that of the catalyst without CeO_2.Adding CeO_2 with a specific surface area of 120.15 m~2/g prepared by hydrothermal reaction time of 39 h to Pt/C synthesis catalyst,its electrocatalytic performance,stability and resistance to poisoning are the best.The electrochemical active surface area is 102.83 m~2/g,the peak current density of ethanol oxidation is 757.17 A/g and steady-state current density of 1100 s is 108.17 A/g which shows the lowest activation energy for ethanol oxidation reaction.When the cyclic voltammogram is scanned for 500 cycles,the oxidation peak current density retention rate is 87.74%.     

Effect of amine activators on the properties of chemical cured dental composites

The purpose of this study was to evaluate the reactivity and the effect of concentration of three tertiary amines upon the mechanical properties of a chemical curing dental composite. Chemical cured composite pastes were prepared by keeping peroxide concentration constant at 1 wt% (by weight of resin mixture) and by varying the amine/peroxide molar ratio from 0.25 to 1.5. Composite samples were prepared for all three amine pastes aged for 1, 15, 30, 45, and 60 d stored at 8, 22, and 37 degrees C. The loss in activity of the tertiary amine with time was measured. Changes in compressive strength, diametral tensile strength, and microhardness were also measured. A sharp decrease in working and setting times corresponding to increased activity was noticed with an increased amine content. The activity was found to vary in the order N,N-dimethyl p-toluidine (DMPT) > 2-(4-dimethylaminophenyl)ethanol (DMAPEA) > N,Ndiethanol p-toluidine (DEPT). DMPT is found to be more temperature sensitive than DMAPEA and DEPT. However, DEPT is found to provide better storage stability out of all three amines tested. Each amine was found to possess optimum concentrations at which the mechanical properties showed maximum values. DEPT is preferred for long-term storage stability in chemical-cured dental composites where aging tends to reduce the activity of the amine.     

活性炭载体的超声波处理对Pt／C催化剂活性的影响分析

通过对活性炭载体进行不同条件的超声波处理获得了具有不同表面化学性质的载体，使用比表面积（BET）、酸碱滴定等技术手段对载体的物理化学性质进行了表征。将经过超声波处理的活性炭载体制备成Pt／C催化剂，并将催化剂直接用于催化反应，考察了活性炭载体的不同超声波处理条件对Pt／C催化剂性能的影响。实验发现，活性炭载体经过超声波处理后，表面灰分含量、pH值和中孔孔容有较大的变化；使用经过60min超声波处理后中孔孔容较大的活性炭作为载体制备的Pt／C催化剂，在催化加氢反应性能测试中显示了最高的催化活性。在此基础上，就活性炭载体的超声波处理对Pt／C催化剂活性的影响进行了讨论。     

钯掺杂α-MnO2无溶剂下催化氧化苯甲醇的性能

通过共沉淀和原位煅烧转化方法, 将Pd掺杂δ-MnO₂前驱体煅烧后制备得到Pd掺杂α-MnO₂纳米棒催化材料.通过氮气物理吸附、X射线衍射、透射电子显微镜、扫描电子显微镜、热重分析、X射线光电子能谱等技术对催化材料进行了表征.扫描电镜和透射电镜结果显示, α-MnO₂纳米棒表面没有明显的Pd纳米颗粒, 表明Pd可能掺杂到α-MnO₂晶格中.纯α-MnO₂的还原温度在390℃左右, 但Pd掺杂可以极大地促进α-MnO₂还原, 还原温度可低至约200℃左右.研究了所制备催化剂在无溶剂条件下对于以分子氧为氧化剂选择性催化氧化苯甲醇为苯甲醛的催化性能.结果表明: 在无溶剂及用纯氧气为氧化剂条件下, Pd掺杂α-MnO₂纳米棒对苯甲醇氧化显示出增强的催化活性; 所掺杂的氧化态Pd物质可增强催化材料中的氧迁移率; 在这些Pd掺杂α-MnO₂催化材料中, 当以Pd (3%, 质量分数) -MnO₂为催化剂时, 在110℃反应4 h后, 苯甲醇的转化率为39%, 远高于同条件下以纯α-MnO₂为催化剂时18. 3%的苯甲醇转化率.      

Influence of Supports on Catalytic Performance and Carbon Deposition of Palladium Catalyst for Methane Partial Oxidation

The catalytic performance of methane partial oxidation was investigated on Pd/CeO2-ZrO2 and Pd/α-Al2O3 catalysts.The catalysts were characterized by XRD,Raman spectra,and TG-DTA techniques.The results show that CeO2-ZrO2 support is more advantageous for the catalytic activity and stability of catalysts compared to α-Al2O3.TG-DTA and Raman spectra results indicated that carbon deposited on the catalysts was in the form of graphite,which is the main reason for the deactivation of catalysts after a 24-hour reaction.Moreover,CeO2-ZrO2 had positive effect on inhibiting carbon deposition.     

偶氮氯膦-pA在痕量铂系元素测定中的应用

报道了偶氮氯膦 pA在痕量铂系元素钌、铑、钯、锇、铱、铂测定中的应用。基于偶氮氯膦 pA与贵金属钯离子能发生显色反应 ,建立了光度法测定痕量钯的新方法 ;基于偶氮氯膦 pA在微量贵金属离子钌、铑、铂、锇、铱存在下与氧化剂 (高碘酸钾、溴酸钾 )发生催化褪色反应 ,建立了测定这些金属元素的催化分光光度新方法。本文考察了该系列反应的最佳条件、检出限及线性范围 ,反应可直接在水溶液中进行 ,方法简便快速 ,灵敏度高 ,用于贵金属精矿、催化剂等样品中微量铂系元素的测定 ,结果满意。     

Catalytic Decomposition of Ozone Gas by a Pd Impregnated MnO2 Catalyst

A new catalyst, which was made of MnO2 impregnated with Pd for decomposition of high humidity ozone gas, was developed and its catalytic activity decrease was analyzed in a finite difference type fixed bed reactor. The activity of the catalyst was higher than that of other catalysts and an activated carbon and does not decrease so much for a long term. Therefore, its lifetime is very long. The reaction rate was shown as a first-order reaction equation for each catalyst in any operation time both under dry and wet conditions. The rate-determining step was considered to be a chemical reaction of ozone. The reaction rate constant kt decreased through two steps, fast in an early period and slowly afterward. Then, kt was analyzed as the function of operation time t and inlet concentration C0 at each humidity. From the analysis, the ozone removal performance in any size of reactor and in any time became possible to predict.