Partial Oxidation of Methane to Syngas over Calcined Ni–Mg/Al Layered Double Hydroxides

The catalytic partial oxidation of CH₄ to syngas was carried out over an Ni–Mg/Al mixed-oxide catalyst prepared from layered double hydroxide-type precursors. The catalysts were characterized by XRD, TPR, UV-DRS, XRF, BET and CHNS analysis. The effects of the catalyst composition and the calcination temperature on the catalytic performance and the extent of catalyst deactivation were investigated. Ni–Mg/Al oxide catalysts converted CH₄ into syngas efficiently with high selectivity. The catalyst performance was strongly related to the Ni particle size and the calcination temperature. The catalysts that were calcined at higher temperature exhibited a better catalytic performance. In conclusion, the NiAl₂O₄ spinel phase had a positive effect on the stability of the catalyst.     

硬脂酸柱撑类水滑石的制备及应用

采用离子交换法制备了硬脂酸柱撑类水滑石,并用红外光谱分析对其进行了表征.通过HAAKE流变仪、颜色测定仪研究了硬脂酸柱撑类水滑石与钙锌热稳定剂并用时的热稳定性,重点考察了水滑石的结构对PVC稳定性能的影响.结果表明硬脂酸柱撑类水滑石与钙皂/锌皂复配显著改善了PVC热老化过程中的初期着色性.     

Zn-Al-CO_3水滑石晶粒尺寸控制与光屏蔽作用研究

在旋转液膜反应器中制备成核浆液 ,通过控制晶化温度制备了不同粒径且晶体结构完整的Zn Al CO3水滑石 (LDHs)。将不同粒径的Zn Al CO3LDHs配成质量分数为 0 0 2 %的水分散液 ,测定在紫外 -可见光范围的透过率 ,结果发现 ,随晶化温度的升高 ,LDHs粒径增大 ,样品对紫外及可见光的阻隔作用增强 ;Zn Al CO3LDHs在不同波长下的吸光度与晶体粒子在a轴和c轴方向的尺寸呈线性关系。由外推法求得了Zn Al CO3LDHs对各波长紫外 -可见光产生屏蔽作用的晶粒尺寸阈值。对波长分别为 2 90、3 2 0、40 0、60 0和 80 0nm光波能够产生屏蔽作用的Zn Al CO3LDHs ,其粒子尺寸在a轴方向需分别大于 3 2 92、3 3 77、3 4 77、3 5 5 6、3 5 79nm ;在c轴方向需分别大于 9 73、12 79、16 47、19 3 5、2 0 2 2nm。     

室温超快速制备HKUST-1及其对甲苯的吸附性能

以硝酸铜和均苯三甲酸为原料,通过水滑石法室温10 s快速制备了一种金属有机骨架材料HKUST-1,对其进行了XRD、SEM和N_2吸附表征,测定了甲苯在HKUST-1上的吸附等温线、动力学和吸附-脱附循环性能。结果表明,水滑石的添加使HKUST-1可在室温10 s内快速合成,HKUST-1的BET比表面积达到2170.7 m~2/g,总孔容为0.97 cm~3/g。HKUST-1在25℃时对甲苯的饱和吸附量达到6.67 mmol/g,在低相对分压(p/p_0≈0.029)下,HKUST-1对甲苯的吸附量高于其他材料约10倍。经5次吸附-脱附循环后,HKUST-1的甲苯饱和吸附量几乎不变,具有很好的再生性能。     

Alkylation of phenol with 1-propanol and 2-propanol over catalysts derived from hydrotalcite-like anionic clays

Vapour phase alkylation of phenol with 1-propanol and 2-propanol was carried out in a fixed-bed flow reactor over calcined magnesium aluminium hydrotalcites (MgAl-CHT) with Mg/Al atomic ratios 2, 3 and 4. MgAl 3.0-CHT showed higher phenol conversion (80% at 350C, in the alkylation of phenol with 1-propanol. Both O- and C-alkylations were found to be taking place without any skeletal isomerization of the propyl moiety, suggesting an S_N2 type mechanism. Isomorphous substitution of Mg²⁺ by Cu²⁺ or Ni²⁺ in the hydrotalcite framework resulted in the predominant C-alkylation to give 2-n-propylphenol (60–70%) with nearly 40–50% phenol conversion at 350C. When 2-propanol was used as an alkylating agent, the phenol conversion decreased over all these catalysts and the alkylation was noticed exclusively at C-centers. Comparison of the product selectivity at constant phenol conversion revealed that CuAl 3.0-CHT is more selective for 2-n-propylphenol and 2-isopropylphenol in the reaction of phenol with 1-propanol and 2-propanol respectively. The participation of a pair of acid-base sites in the calcined hydrotalcites for the alkylation reaction has been proposed. The acid-base properties of these catalysts have been examined by the decomposition of cyclohexanol as a test reaction. Analysis of the spent catalysts revealed that Cu²⁺ in CuO gets reduced into Cu¹⁺ and metallic copper during the reaction in the case of CuAl-CHT, while MgO and NiO phases of MgAl-CHT and NiAl-CHT are retained.     

水滑石形成机理与形貌控制的研究现状

综述了水滑石生长机理研究的几种典型理论和影响水滑石形貌、尺寸和结构控制的因素,重点介绍了不同制备方法对形貌特征的影响。     

烧制工艺对氧化镁活性的影响

为获取高活性氧化镁，以提供镁铝水滑石阻燃剂制备的实验依据，采用X射线衍射研究烧制工艺与氧化镁的结晶状态的关系，结果发现烧制温度和烧制时间对氧化镁的活性有较大的影响，而不同活性的氧化镁对镁铝水滑石有决定性影响。在500℃-750℃的范围内，镁盐的烧制温度为500℃-550℃，保温时间2h，这样的氧化镁的活性最大，用其制备镁铝水滑石试样纯度较高。     

新型氯离子吸附剂的制备及性能研究

利用低饱和共沉淀法、焙烧还原法,制备活性炭改性焙烧镁铝水滑石。将其作为吸附剂,处理质量浓度为100mg/L的含氯模拟废水。实验结果与传统水滑石比较,氯离子吸附率提高6.22%,成本降低35.42%。在性价比方面明显优于传统水滑石,具有明显的环境与经济效益。     

镁铝水滑石纳米片可控制备及其吸附性能研究

在聚乙二醇(PEG)存在的条件下,通过一步水热法合成了晶相单一的六方片状镁铝水滑石层状双氢氧化物(LDH)。采用XRD、SEM、TEM、FT-IR、N2吸附、UV-Vis紫外-分光光度计和zeta电位仪等对产物进行了表征。考察了PEG活性剂对水滑石形貌及性能的影响。结果表明,添加活性剂改性后制备的六边形水滑石纳米片形貌规整均一,宽约几微米,厚度约为100~200 nm,纳米片间易形成交叉支撑结构,分散性好,比表面积为203.5 m2/g。在室温,焙烧后的Mg AlLDO对浓度为100 mg/L的刚果红30 min内去除率可达97%,饱和吸附量为243.5 mg/g。     

表面改性水滑石的制备及其耐腐蚀性能研究

通过水热合成法制备一种硝酸根插层的Zn-Al水滑石,利用静电作用在水滑石表面沉积聚天冬氨酸,以其作为交联剂与缓蚀剂三价铈离子络合,完成对水滑石表面的改性;将改性后的Zn-Al水滑石分散在双组分水性环氧涂层中。扫描电子显微镜 (SEM) 和X射线衍射 (XRD) 的表面形貌和晶体结构分析、ζ电势测试以及EIS阻抗谱测试结果表明,表面改性后的水滑石应用于环氧涂层中能够起到明显的自修复效果,并能提高涂层的耐腐蚀性能。