负载型催化剂上Mo含量的ICP-AES法测定

用氢氟酸对负载型Mo催化剂进行预处理,并用ICP-AES法测定了Mo的含量。方法中Mo元素的检出限为8.220 ng·mL-1,加标回收率为102.6%～104.3%,11次测定的RSD(n=11)小于0.860%。方法操作方便,分析速度快,结果准确。利用该法测定不同条件下制备的负载型Mo催化剂上Mo的含量,结果表明,负载型钼催化剂在制备过程中,活性组分钼都有一定量的流失。不同浸渍液浓度和焙烧温度所制备的催化剂,其活性组分Mo的流失量各不相同。     

ICP-AES法测定Pd/Al_2O_3中钯的干扰问题

本文研究了用 ICP- AES法测定 Pd/Al2 O3催化剂中钯所存在的干扰问题。考察了基体及所用试剂对钯测定的影响 ,发现氧化铝基体、硫酸等对钯的测定均有负干扰 ,提出采用基体匹配法测定 Pd/Al2 O3中的钯含量。方法回收率在 96%以上 ,9次测定相对标准偏差小于 3%     

锆对低温液相合成甲醇Cu-Cr催化剂性能的影响

用络合共沉淀法制备了Cu Cr和Cu Cr Zr低温液相合成甲醇催化剂,其比表面积分别达到了77. 9和113. 2m2 /g.在5. 5MPa、383和423K的条件下,用间歇式反应釜考察了催化剂的活性和选择性,并用化学分析的方法测定了反应后溶液中钠化合物含量的变化.结果表明, Cu Cr Zr的活性明显高于Cu Cr,其甲醇的选择性则略有下降;同时,由反应后的钠化合物分析发现, Cu Cr Zr催化体系在423K反应后,溶液中甲酸钠的浓度降低,导致催化体系失活的甲醇钠转化为甲酸钠的反应被彻底抑制.     

Pd-Cu双金属催化剂上加氢反应的仲氢诱导超极化研究

本文通过多相催化-仲氢诱导超极化（HET-PHIP）核磁共振（NMR）技术研究了Pd-Cu/SiO₂双金属催化剂上丙炔选择性加氢反应.首先利用等体积浸渍法和连续浸渍法合成了一系列不同Pd/Cu比例和形貌的Pd-Cu/SiO₂双金属催化剂.通过ALTADENA（Adiabatic Longitudinal Transport After Dissociation Engenders Net Alignment）方法发现,催化剂的Pd/Cu比例和形貌均对PHIP的极化效率有较大影响.随着Pd-Cu双金属催化剂中Pd比例的增大,PHIP极化效率降低,同时反应活性增强.在同Pd/Cu比例下,相对于等体积浸渍法,连续浸渍法制备的层叠形貌催化剂具有较弱的极化效率以及较强的催化活性,这是由于催化剂表面暴露出的Pd数量增多,导致催化活性增强;同时单个Pd集簇表面积增大,使得氢原子移动范围扩大,从而造成极化效率降低.     

葡萄糖催化氧化反应用Pd-Co/C催化剂的XPS研究

活性炭为载体，制备了Pd/C、Pd-Co/C催化剂，并进行了活性评价和XPS表征。在Pd-Co／C催化剂上反应3h后，葡萄糖的转化率达92％，选择性为94％，较Pd/C催化剂有显著提高。Co的添加及焙烧过程改变了Pd/C催化剂的表面组成及结构，提高了贵金属Pd在催化剂表面的分散程度，有利于Pd的还原，使Pd-Co/C催化剂表现出良好的催化活性和选择性。     

火焰原子吸收光谱法快速测定蜂蜜中的锰和镁

应用火焰原子吸收光谱法测定蜂蜜中锰和镁的含量,分别采用酸消解法和酸浸提法对样品进行预处理。探讨了酸浸提法快速测定蜂蜜中锰和镁的可行性。实验结果表明,两种预处理方法所获得的结果吻合。酸浸提法测定锰和镁的相对标准偏差分别为2.74%—3.47%和1.65%—1.69%;方法的回收率分别为98.0%和97.4%。     

ICP—AES法测定Pd／Al2O3中钯的干扰问题

本文研究了用ICP－AES法测定Pd/Al2O3催化剂中钯所存在的干扰问题,考察了基体及所用试剂对钯测定的影响,发现氧化铝基体,硫酸等对钯的测定均有负干扰,提出采用基本匹配法测定Pd/Al2O3中的钯含量,方法回收率在96％以上,9次测定相对标准偏差小于3％。     

CO选择性氧化用Cu_1Zr_1Ce_9O_δ催化剂的红外光谱研究

采用共沉淀法制备了Cu1Zr1Ce9Oδ催化剂,用于富氢气体中CO的选择性氧化反应,利用原位漫反射红外光谱技术考察了Cu1Zr1Ce9Oδ催化剂表面上的吸附物种和反应中间产物。研究发现,H2,O2和CO物种竞争吸附于Cu1Zr1Ce9Oδ表面相同的吸附位上。氢气预处理会引起Cu1Zr1Ce9Oδ催化剂上Cu+物种的深度还原,降低了CO的吸附量。氧气预处理为催化剂提供了较多的活性氧物种,同时抑制了Cu+物种的深度还原。氦气预处理仅起到净化催化剂表面的作用。180℃时Cu1Zr1Ce9Oδ催化剂在2938.7和2843.8cm-1处出现桥式和双齿型甲酸根物种的红外吸收峰。Cu1Zr1Ce9Oδ催化剂上活性较高的氧阴离子在常温下即可将催化剂表面上吸附的CO氧化成表面碳酸根。甲酸根和碳酸根物种占据Cu1Zr1Ce9Oδ催化剂的吸附中心,导致催化剂活性降低。300℃下用氦气吹扫Cu1Zr1Ce9Oδ催化剂表面,双齿型的甲酸根物种分解生成碳酸根物种,碳酸根物种再继续分解生成CO2,释放出催化剂表面的吸附位,恢复了Cu1Zr1Ce9Oδ催化剂的活性。     

Cu/ZSM-5催化剂制备及SCR催化性能研究

采用固态离子交换法制备了不同Cu含量的Cu/ZSM-5改性分子筛型催化剂,并对其理化特性及SCR反应活性进行了表征。结果表明:所制备催化剂中Cu元素富集于分子筛的浅层及表面,并主要以二价铜的形式存在;随Cu含量增加,低温弱酸吸附峰和中温中强酸吸附峰面积增加,有利于提高低温SCR催化性能;铜含量超过13%后,Cu含量的增加对催化剂的低温SCR催化活性影响不大,但将导致高温SCR催化性能急剧恶化;b4催化剂兼具良好的高、低温SCR催化性能,值得深入研究。     

原子吸收法直接测定食用L-赖氨酸盐酸盐中的铜和铅

本文报道了用石墨炉-原子吸收分析法，将食用L-赖氨酸盐样品经稀酸溶解后，直接进样测定。该方法省去了通常必需的干灰化或湿消解过程，充分利用石墨炉本身所具的对样品进行部分预处理的功能，在无基体改进剂的条件下，快速测定样品中的Cu和Pb的含量。方法简便，快速，准确，实用，Cu和Pb的精密度试验的相对标准偏差分别为4.8%和5.3%；回收率分别为100%-110%和102%-105%。     

小试金富集ICP-AES法同时测定试样中的铂、钯、金

文章报道了用小试金富集ICP AES法同时测定试样中的铂、钯和金 ,将 1 0～ 2 0g试样中的铂、钯、金富集在毫克量的银合粒中 ,制成溶液后用ICP AES法同时测定铂、钯和金。该方法的检出限 (μg·mL-1 )Pt,Pd ,Au分别为 0 0 1 ,0 0 0 5 ,0 0 1 ,相对标准偏差 (RSD ,n =1 0 )分别为 0 1 % ,0 1 2 % ,0 0 9% ,标准回收率均在 97%以上。生产实践表明 ,本方法是一种快速、简便、准确的分析方法 ,已被我们应用于测定样品中的铂 ,钯和金     

Synthesis, characterization and effect of calcination temperature on phase transformation and photocatalytic activity of Cu,S-codoped TiO2 nanoparticles

A novel copper and sulfur codoped TiO₂ photocatalyst was synthesized by modified sol-gel method using titanium(IV) isopropoxide, CuCl₂·2H₂O and thiourea as precursors. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy equipped with energy dispersive X-ray micro-analysis (SEM-EDX), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) analysis. The XRD results showed undoped and Cu,S-codoped TiO₂ nanoparticles only include anatase phase. Effect of calcination temperature showed rutile phase appears in 650 and 700 °C for undoped and 0.1% Cu,S-codoped TiO₂, respectively. The SEM analysis revealed the doping of Cu and S does not leave any change in morphology of the catalyst surface. The increase of copper doping enhanced “red-shift” in the UV-vis absorption spectra. The TEM images confirmed the dopants suppressed the growth of TiO₂ grains. The photocatalytic activity of samples was tested for degradation of methyl orange (MO) solutions. The results showed photocatalytic activity of the catalysts with 0.05% Cu,0.05% S and 0.1% Cu,0.05% S were higher than that of other catalysts under ultraviolet (UV) and visible irradiation, respectively. Because of synergetic effect of S and Cu, the Cu,S-codoped TiO₂ catalyst has higher activity than undoped and Cu or S doped TiO₂ catalysts.     

An XPS study of CrOx on a thin alumina film and in alumina supported catalysts

We have investigated chromium layers evaporated onto a thin alumina film at room temperature. The oxidation and reduction behavior of this model catalyst was compared to atomic layer deposition (ALD) and impregnated alumina supported catalysts using X-ray photoelectron spectroscopy (XPS) with a detailed analysis method utilizing asymmetric peak shapes to represent both metallic and oxidic states. The ALD and impregnated catalysts were measured after calcination in air and after reduction with several gases at 850 K. Both catalysts show Cr³⁺ and Cr⁶⁺ species after calcination and mostly Cr³⁺ after reduction. The chromium layers deposited in vacuum show initially small partial oxidation due to the interaction with the oxygen terminated alumina film. These model catalysts can be oxidized in vacuum to Cr³⁺ species but not to higher oxidation states. The model catalysts were also subjected to calcination and reduction treatments after deposition in vacuum. Under these conditions the model systems exhibit similar oxidation/reduction behavior as the supported catalysts. Photoreduction of Cr⁶⁺ during the measurements was also studied and found to be very slow having a negligible effect on the results.     

煅烧温度对Cu/HMOR催化剂结构及其催化二甲醚羰基化反应性能影响

采用离子交换法在不同煅烧温度下制备HMOR负载Cu(Cu/HMOR)催化剂,用于催化二甲醚(DME)羰基化合成乙酸甲酯(MA)反应. 活性测试结果表明430 oC煅烧制得Cu/HMOR具有较好催化活性,在210 oC、1.5 MPa、空速4883 h^-1下DME转化率为97.2%,MA选择性为97.9%. 对催化剂进行X射线衍射、N₂物理吸附、NH₃程序升温脱附、CO程序升温脱附及拉曼方法表征. 催化剂经一定的煅烧温度有利于Cu离子迁移及扩散和硝酸铜完全分解,从而使HMOR载体具有较多的酸性活性位、大比表面、适宜的微孔结构以及更多的CO吸附位.     

Preparation and characterization of CuZnAl catalysts by citrate gel process

CuZnAl catalysts with different Cu loading (1-23 wt%) and a Zn:Al atomic ratio nearly constant (Zn:Al≅0.6), were prepared by the citrate sol-gel method and characterized by different techniques such as TG, BET, TPR, XRD and FTIR. The final structure obtained was strongly influenced by the calcination temperature and metal precursor composition. XRD and quantitative Rietveld revealed Zn and Al species were mainly incorporated into the normal spinel matrix and copper predominantly forms CuO. The formation of a ZnAl₂O₄ spinel was favored by increasing Cu amounts and/or by increasing calcination temperature (from 500° to 700 °C). The spinel phase of the catalysts calcined at 700 °C, had a good thermal stability and it was preserved after TPR measurements. Under hydrogen atmosphere Cu²⁺ was fully reduced to Cu⁰. Although the composition and the calcination temperature have a strong influence on the phase nature in CuZnAl catalysts, the reducibility of Cu species changes in a non significant way.     

固-液-气三相环境下非均相苯加氢反应的原位核磁共振研究

本文使用原位核磁共振（NMR）方法成功实现了对固-液-气三相环境下加氢反应的在线监测.在反应过程中,无需分离产物.以Pd纳米颗粒粉末及不同晶面形貌的Pd催化剂作为研究对象,我们研究了反应压强、反应时间,以及催化剂表面性质对加氢反应的影响.结果表明,压强和反应时间都可以影响加氢反应产物的产率,使用暴露不同晶面的Pd共催化剂时,苯加氢产物不同.该原位NMR方法为研究固-液-气三相催化环境下的加氢反应机理提供了可能.