含铬样品中铝、铁、镁元素的快速测定

利用“DHF多元素快速分析仪”研究了样品中Al2O3、Fe2O3、MgO与Cr2O3共存时，Cr2O3对Al2O3、Fe2O3和MgO的测定结果的干扰规律，提出了准确测量含Cr2O3样品中Al2O3、Fe2O3和MgO快速测定方法－－空白抵消法。通过对比实验证明，该方法准确度较高，误差在国家标准允许误差范围之内。本法适用于Cr2O3含量＜5％的样品中的Al2O3、Fe2O3和MgO的快速测定。     

Defect Structure of PLZT Doped with Mn, Fe, and Al

Practically pore-free Mn-, Fe-, and Al-doped PLZT ceramics were prepared using isostatic hot-pressing. The incorporation of the dopants in the perovskite lattice of PLZT (Pb_0.9La_0.1 |Zr_0.5Ti_o.5O₃₊δ) ceramics was analyzed from measurements of the density, lattice constants, and weight loss during sintering. It was deduced that Mn, Fe, and Al are incorporated as trivalent ions at (Zr, Ti)⁴⁺ sites and that charge compensation is effected by elimination of cation vacancies present in the undoped PLZT.     

等离子体制备稀土金属掺杂甲烷干气重整Ni/Mg/Al催化剂研究

采用冷等离子体炬技术制备了以水滑石为前驱体的Ni/Mg/Al催化剂,考察了La和Ce助剂的添加对催化剂结构及其对CH4和CO2重整催化性能的影响。利用XRD、BET、XPS及TG对催化剂进行了表征和性能测试。结果表明：冷等离子体炬能快速分解Ni/Mg/Al水滑石前驱体,生成具有介孔特性的水镁石相Mg(Ni,Al)O固溶体,并生成Ni0晶粒。在温度700℃,空速30000mL/(h·gcat), V（CH4）：V（CO2）=4：6的条件下,CH4和CO2的转化率分别为76%和61.8%。助剂Ce的添加增加了晶格氧,促进催化剂表面碳物种的消除,CH4和CO2的转化率分别提高了5%和7%。La的加入,抑制了Ni晶粒的团聚,增加了Ni的分散度,与未添加La的催化剂相比非活性碳的生成量减少70%,表现出良好的抗积炭性能。     

利用X射线荧光光谱仪测定铬矿石中的Cr、Fe、Si、Al、Ca、Mg的含量

采用合适的溶剂,将铬矿石粉末样品熔融成适合X射线荧光光谱仪测量的玻璃片,消除样品的矿物效应和颗粒效应。选取标准样品,建立标准曲线,同时对元素间干扰效应进行校正,使用X射线荧光光谱仪对铬矿石中的Cr、Fe、Si、Al、Ca、Mg等待测元素进行测定。分析结果与标准值相吻合,分析方法具有快速、准确、环保等优点。     

硫酸氢钾催化合成丙酸丁酯

用硫酸氢钾催化丙酸和正丁醇的酯化反应合成了丙酸丁酯。研究结果表明:硫酸氢钾具有较高的催化活性。在典型反应条件下,丙酸丁酯的收率达86.6%,催化剂可重复使用。     

叔丁醇钾催化合成N,N-二苯基叔胺类化合物

以乙腈作溶剂,苄基溴和二苯胺在叔丁醇钾的催化下,可以直接合成得到N,N-二苯基苄叔胺类化合物,产率60.2%~81.4%。产物经1 H NMR、13 C NMR和GC-MS确证。得出合成N,N-二苯基叔胺最优化条件为n(苄基溴)∶n(二苯胺)∶n(叔丁醇钾)=1.5∶1∶1,以乙腈为溶剂,室温下反应12h。该方法具有反应条件温和,操作简单,产率较高等优点。     

等离子体制备稀土金属掺杂甲烷干气重整Ni/Mg/Al催化剂

采用冷等离子体炬技术制备了以水滑石为前驱体的Ni/Mg/Al催化剂,考察了La和Ce助剂的添加对催化剂结构及其对CH_4和CO_2重整催化性能的影响。利用XRD、BET、XPS及TG对催化剂进行了表征和性能测试。结果表明:冷等离子体炬能快速分解Ni/Mg/Al水滑石前驱体,生成具有介孔特性的水镁石相Mg(Ni,Al)O固溶体,并生成Ni0晶粒。在温度700℃、空速30 000 m L/(h·gcat)、V(CH4)∶V(CO2)=4∶6时,CH_4和CO_2的转化率分别为76.6%和61.8%。助剂Ce的添加增加了晶格氧的含量,促进了催化剂表面碳物种的消除,CH_4和CO_2的转化率分别提高了4%和7%。La的加入,抑制了Ni0晶粒的团聚,增加了Ni0的分散度,与未添加La的催化剂相比,非活性碳的生成量减少70%,表现出良好的抗积炭性能。     

The Effect of Thermal Pre-Treatment on Structure, Composition, Basicity and Catalytic Activity of Mg/Al Mixed Oxides

The goal of this work is to study the effect of thermal pre-treatment of Mg/Al mixed oxides (450–1,050 °C) on their structure, basicity and catalytic activity in transesterification of rapeseed oil. The catalytic activity of Mg/Al catalysts was shown to depend not only on the amount of basic sites, but also on crystallite size of MgO, specific surface area and population of medium/strong basic sites. Moreover, high stability of Mg/Al-550 was established by re-using the catalyst four times. It was associated with negligible magnesium leaching from the solid catalyst to liquid phases.     

Formation and properties of high entropy oxides in Co-Cr-Fe-Mg-Mn-Ni-O system: Novel (Cr,Fe,Mg,Mn,Ni)3O4 and (Co,Cr,Fe,Mg,Mn)3O4 high entropy spinels

Possibility of formation of quinary and senary equimolar high entropy oxides from the Co-Cr-Fe-Mg-Mn-Ni-O system is presented. Different proposed compositions are synthesized using the solid-state reaction route at high temperatures (900−1100 °C) and quenched to room temperature. Phase composition of the samples is studied, showing tendency toward formation of two main phases: rock salt-structured Fm-3 m and spinel-structured Fd-3 m. It is documented that the annealing temperature has a profound effect on stability of both structures, and at 1100 °C usually the highest content of Fm-3 m phase is usually observed. Three different oxides, namely, (Co,Cr,Fe,Mn,Ni)₃O₄, (Co,Cr,Fe,Mg,Mn)₃O₄ and (Cr,Fe,Mg,Mn,Ni)₃O₄ are obtained as single-phase materials, which structure can be described as the high entropy Fd-3 m spinel one. The latter two compounds have not been previously reported in the literature. Activated character of the electrical conductivity dependence on temperature is observed, with relatively high total conductivity at high temperatures and corresponding high absolute values of Seebeck coefficient.     

Catalytic Properties of Cr2O3 Doped with MgO Supported on MgF2 and Al2O3

Catalytic properties of Cr₂O₃ supported on MgF₂ or Al₂O₃ have been modified by magnesium oxide. The catalysts have been obtained by the co-impregnation method and characterised by: BET, XRD and TPR. As follows from the results, the oxides supported on magnesium fluorine react with each other already at 400 °C, leading to formation of an amorphous spinel-like phase. On the Al₂O₃ support such an MgCr₂O₄ spinel has appeared at much higher temperatures. The addition of magnesium oxide has a significant effect on the activity and selectivity of the catalysts studied in the CO oxidation reaction at room temperature and in the reaction of cyclohexane dehydrogenation. The magnesium–chromium catalysts supported on MgF₂ have been found to show much higher activity and selectivity than the analogous systems supported on Al₂O₃.     

镁铝及镁锌铝水滑石的合成与表征

采用共沉淀法合成镁铝及镁锌铝水滑石,并通过X射线衍射（XRD）、红外光谱（FT-IR）、扫描电镜（SEM）、热分析（TG/DTG）、粒度分析等手段对合成的水滑石进行表征,研究不同镁、铝、锌的投料比例对合成的水滑石结构及热性能等的影响。XRD表征结果表明,合成产物均具有水滑石特征峰。合成的镁铝水滑石随着镁铝比的增加其层板间距增大,层板上原子密度降低;合成的镁锌铝水滑石随着锌含量的提高层板间距减小,层板上原子密度降低。镁铝水滑石热分解过程有两个明显阶段,层间结晶水先脱除,随后是层间阴离子脱除及层板上部分羟基脱水;镁锌铝水滑石热分解过程只有一个明显的阶段,层板间阴离子在层板间结晶水脱除的同时也在脱除。     

Catalytic performance of MIL-100 (Fe,Cr) and MIL-101 (Fe,Cr) in the isomerization of endo- to exo-dicyclopentadiene

MIL-100 (Fe, Cr) and MIL-101 (Fe, Cr), metal-organic frameworks (MOFs), have been assessed in solvent-free isomerization of dicyclopentadiene (DCPD) from the endo- to exo-form. In the isomerization reaction, the conversion of endo-DCPD and selectivity for the exo-dimer strongly depend on the nature of the active metal center. The MIL-100 (Fe) catalyst possessing more acid sites shows the highest catalytic activity among the MILs and it was readily recoverable and reusable in subsequent reaction cycles for the isomerization. The effects of reaction parameters such as temperature, reaction time, and catalyst loading on the reactivity were also investigated.     

ICP-AES法同时测定高含量SiC中的Fe、Al、Ca、Mg

研究了ICP-AES法测定高含量SiC中的Fe、Al、Ca、Mg的分析方法,对共存元素、仪器分析参数等因素进行了研究,确定了仪器的最佳分析条件,建立了一种可同时测定Fe、Al、Ca、Mg含量的简单、快速的分析方法,其测定结果与湿量法的测定值一致,完全能满足生产和科研的需要。     

Ti-HMS合成、表征及其催化氧化性能研究

以有机金属二氯二茂钛为钛源,六方介孔二氧化硅分子筛(HMS)为载体,采用嫁接法合成了含钛量(mol)分别为2.8%、3.8%和4.8%的Ti-HMS,HMS合成原料组成中H2O/EtOH(v/v)分别为0.5、1、2、5、9.合成材料用X射线粉末衍射(XRD)、N2吸附-脱附等温线、漫反射紫外可见光谱(UV-VIS)进行了表征,并考察了它们以叔丁基过氧化物(TBHP)为氧化剂在对叔丁基甲苯液相氧化中的催化性能.结果表明,表面钛嫁接后的HMS介孔结构有所损失,比表面积和孔体积减少.载体HMS合成原料中的H2O/EtOH(v/v)影响介孔织构和钛的配位环境.UV-VIS资料表明,H2O/EtOH(v/v)=0.5和9时不利于钛着床于分子筛骨架,H2O/EtOH(v/v)=1、2和5的HMS适合作为嫁接钛的载体.催化剂的活性主要受四配位Ti、介孔织构的影响.钛嫁接的HMS在氧化反应中表现出较好的催化活性,载钛量为4.8%Ti、H2O/EtOH(v/v)=1的Ti-HMS显示最好催化活性,对叔丁基甲苯转化率为21.8%.     

ICP-OES法测定铝镍钴磁钢铝、镍、钴、铁和铜含量

采用微波消解电感耦合等离子体原子发射光谱(ICP-OES)法测定了铝镍钴磁钢废料中的铝、镍、钴、铁和铜元素。结果表明:微波消解以硝酸为介质溶解样品所得溶液清亮,无残渣;铝、镍、钴、铁和铜元素的线性良好,相关系数在0.9997～0.9999之间,标加回收率在98.84%～102.00%之间,方法精密度RSD≤0.21%。该方法操作简单易行、灵敏度高、重复性好,与x-荧光光谱法、化学容量法的对照结果表明,测试结果可靠性强。     

DUO-ICP-AES测定精对苯二甲酸中的钴、铬、铁、锰、钼、镍、钛

采用DUO-ICP-AES同时测定精对苯二甲酸中钴、铬、铁、锰、钼、镍、钛,并对仪器的分析线选择、背景校正、入射功率、雾化器压力、辅助气流量、冷却气流量、蠕动泵转速的影响及共存元素的干扰、硝酸铯灰化助剂等因素进行了详细的研究。方法的检测限:钴0.0097 mg/L;铬0.0021 mg/L;铁0.0078 mg/L;锰0.0012 mg/L;钼0.0027 mg/L;镍0.016 mg/L;钛0.0027 mg/L,回收率和精密度分别为93.0%～99.5%和0.37%～3.2%。该方法快速简便,具有良好的精密度和准确度,适用于进出口精对苯二甲酸的日常检验。     

Fe、Ni、Co-吡啶配合物对环多烯烃的均相选择催化氢化

研究了环多烯径的烯键在M(Fe、Ni、Co）-吡啶配合物存在下的均相选择催化氢化。结果表明,该催化体系对环多烯烃的烯键具有高的催化活性和良好的选择性。讨论了配合物中心元素和环多烯烃构造对催化氢化反应的影响,同时提出了反应过程的机理。     

火焰原子吸收光谱法分析精对苯二甲酸中锰、钴、铁、铬、钼和镍

采用火焰原子吸收光谱法分析精对苯二甲酸中的锰、钴、铁、铬、钼和镍。结果表明,精对苯二甲酸灰化温度600℃比较合适,六种金属标准曲线相关系数均大于0．9990,检出限在0．000726-0．009849μg／mL之间,分析结果最大相对误差10％,相对标准偏差5．0％,用硝酸和盐酸溶解灰份效果最好,加标回收率在90％-107％之间。     

锡离子改性固体超强酸催化合成乙酸丁酯

采用sol-gel法制备了固体超强酸SO42-/ZrO2和Sn（Ⅳ）SZ催化剂,用Hammett指示剂法对催化剂酸强度进行表征,并考察了其对乙酸和正丁醇的酯化活性,实验结果表明,Sn（Ⅳ）SZ的活性优于SO42-/ZrO2。实验优化条件：醇酸摩尔比1.4∶1,Sn（Ⅳ）SZ催化剂用量为0.5g（乙酸0.41mol）,反应时间为3～4h,乙酸转化率可达96%以上。