Y型沸石钙交换过程及机理研究

采用PASCA、NMR、IR等技术研究NaY沸石钙交换过程及机理.结果表明,NaY沸石中引入钙离子(钙交换度>20%时)并在水蒸气气氛中焙烧,可导致沸石骨架中产生非骨架铝(NFAl)和大量平均孔直径达到18nm的二次孔道(SP).产生最大数量的NFAl和产生最多SP的最佳交换度为60%,此时CaNaY沸石中含有最大量的B酸和最大量的L酸.结果还表明,在钙交换过程中,钙必须以Ca~(2 )离子的形式交换在NaY沸石骨架上,因此,交换过程中控制好浆液的pH值是必要的,最佳pH值为5.5.CaNaY沸石的最佳水热处理温度为550℃.     

The Effect of Metal Dispersion on Ni/Al2O3 Wax Hydrofining Catalyst

Positron annihilation spectroscopy for chemical analysis (PASCA), powder x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) were used to study the effect of calcination temperature on active metal dispersion of wax hydrofining catalyst. The experimental results showed that, with the increase of calcination temperature, the metal Ni and the support Al₂O₃ interaction became weaker. When calcination temperature reached 280°C, Ni(NO₃)₂ began to decompose and the inhibition effect of NO₃^- began to diminish. At 380°C, Ni(NO₃)₂ was almost decomposed, and NiO still had a high dispersion on the catalyst surface. At 440°C or higher, Ni(NO₃)₂ was completely decomposed, and to some extent, NiO aggregated on the catalyst surface in the form of noncrystalline clusters (atomic clusters). The most suitable calcination temperature in the experiment for the catalyst Ni/Al₂O₃ was 440°C or a little higher.     

催化化学中的核技术—PASCA

介绍近年来应用ＰＡＳＣＡ技术研究石油加工催化剂方面的进展，其中某些结果已直接用于指导新型指导新型催化剂的开发，并取得了相当的成功。     

载体、金属-载体相互作用与多相催化剂的制备

对多相(非均相)催化剂主要是Mo(w)Ni(Co)／A12O3加氢处理催化剂和PtRe／Al2O3催化重整催化剂的制备研究作一概述。讨论的重点集中在原子水平上研究载体的性质、金属一载体之间的相互作用，及其对载体和相应催化剂的表面性质或表面结构(形貌)的影响。除了采用TPR、DRS、ESCA、IR和微型反应色谱等技术之外，还采用了一种新的表面测试技术PASCA(Positron annihilation spectroscopy for chemical analysis)来表征这两类催化剂。基于这些研究结果，提出了开发新型加氢处理和催化重整催化剂的总体思路。     

采用PASCA技术研究正电子素ο-Ps在MoNi／Al2O3加氢催化剂上的反应动力学

采用化学分析正电子湮没谱（PASCA）技术研究正电子素（ο-Ps）在MoNi／Al2O3加氢催化剂上的反应动力学。在20～100℃、1×10^-5Pa真空度下，得到ο-Ps在催化剂上反应的表观活化能为11，09KJ／mol、反应频率因子（A）为1，178×10^10kg／（mol·s）和反应速率常数（K）为1．344×10^8kg／（mol·s）（25℃），并在此基础上建立了反应动力学方程。进一步探讨了同一载体担载不同金属时反应速率常数变化的规律，发现其中的特征关联常数（k）只与Al2O3载体本身特征有关，而与其所担载的金属类型无关。用k值可以定量表征金属-载体之间的相互作用程度（MSI），为指导加氢催化剂的开发和性能改进提供新的表征手段。     

Characterization of Hydrotreating Catalysts in Fundamental Research and Development

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The Effect of Metal Dispersion on Ni/Al2O3 Wax Hydrofining Catalyst

Abstract

Positron annihilation spectroscopy for chemical analysis (PASCA), powder x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) were used to study the effect of calcination temperature on active metal dispersion of wax hydrofining catalyst. The experimental results showed that, with the increase of calcination temperature, the metal Ni and the support Al₂O₃ interaction became weaker. When calcination temperature reached 280°C, Ni(NO₃)₂ began to decompose and the inhibition effect of NO₃ ^? began to diminish. At 380°C, Ni(NO₃)₂ was almost decomposed, and NiO still had a high dispersion on the catalyst surface. At 440°C or higher, Ni(NO₃)₂ was completely decomposed, and to some extent, NiO aggregated on the catalyst surface in the form of noncrystalline clusters (atomic clusters). The most suitable calcination temperature in the experiment for the catalyst Ni/Al₂O₃ was 440°C or a little higher.     

采用PASCA技术研究正电子素o-Ps在MoNi/Al2O3加氢催化剂上的反应动力学

采用化学分析正电子湮没谱(PASCA)技术研究正电子素(o-Ps)在MoNi/Al2O3加氢催化剂上的反应动力学。在20-100℃、1×10-5Pa真空度下,得到o-Ps在催化剂上反应的表观活化能为11.09 kJ/mol、反应频率因子(A)为1.178×1010kg/(mol.s)和反应速率常数(K)为1.344×108kg/(mol.s)(25℃),并在此基础上建立了反应动力学方程。进一步探讨了同一载体担载不同金属时反应速率常数变化的规律,发现其中的特征关联常数(k)只与Al2O3载体本身特征有关,而与其所担载的金属类型无关。用k值可以定量表征金属-载体之间的相互作用程度(MSI),为指导加氢催化剂的开发和性能改进提供新的表征手段。