Mesoporous gamma-Al2O3 is one of the most widely used catalyst supports for commercial catalytic applications. The performance of a catalyst strongly depends on the combination of textural, chemical and physical properties of the support. Pore size is essential since each catalytic system requires a unique pore size for optimal catalyst loading, diffusion and selectivity. In addition, high surface area and large pore volume usually result in higher catalyst loading, which increases the number of catalytic reaction sites and decreases reaction time. Therefore, determination of surface area and porosity of porous supports is critical for the successful design and optimization of a catalyst support. Moreover, it is important to produce supports with good thermal stability since pore collapsing due to sintering at high temperatures often results in catalyst deactivation. In addition, the ability to control the acidity of the catalyst enables us to design desirable acid sites to optimize product selectivity, activity, and stability in different catalytic applications.;This dissertation presents a simple, one-pot, solvent-deficient method to synthesize thermally stable silica-doped alumina (SDA) without using templates. The XRD (X-ray diffraction), HTXRD (high temperature X-ray diffraction), SS NMR (solid state nuclear magnetic resonance), TEM (transmission electron microscopy), TGA (thermogravimetric analysis), and N2 adosorption techniques are used to characterize the structures of the synthesized SDAs and understand the origin of increased thermal stability. The obtained SDAs have a surface area of 160 m2/g, pore volume of 0.99 cm 3/g, and a bimodal pore size distribution of 23 and 52 nm after calcination at 1100°C. Compared to a commercial SDA, the surface area, pore volume, and pore diameter of synthesized SDAs are higher by 46%, 155%, and 94%, respectively. A split-plot fractional-factorial experimental design is also used to obtain a useful mathematical model for the control of textural properties of SDAs with a reduced cost and number of experiments. The proposed quantitative models can predict optimal conditions to produce SDAs with high surface areas greater than 250 m2/g, large pore volume greater than 1 cm3 /g, and large (40-60 nm) or medium (16-19 nm) pore diameters.;In my approach, I control acid sites formation by altering preparation variables in the synthesis method such as Si/Al ratio and calcination temperatures. The total acidity concentration (Bronsted and Lewis) of the synthesized SDAs are determined using ammonia temperatured program, pyridine fourier transform infrared spectroscopy (FTIR), and MAS NMR. The total acidity concentration is increased by introducing a higher mole ratio of Si to Al. In addition, the total acidity concentration is decreased by increasing calcination temperature while maintaining high surface area, large porosity, and thermal stability of gamma-alumina support.;I also present an optimized synthesis of various aluminum alkoxides (aluminum n-hexyloxide (AH), aluminum phenoxide (APh) and aluminum isopropoxide (AIP)) with high yields (90-95%). One mole of aluminum is reacted with excess alcohol in the presence of 0.1 mole % mercuric chloride catalyst. The synthesized aluminum alkoxides are used as starting materials to produce high surface area alumina catalyst supports. Aluminum alkoxides and nano aluminas are analyzed by 1H NMR, 13C NMR, 27Al NMR, gCOSY (2D nuclear magnetic resonance spectroscopy), IR (infrared spectroscopy), XRD, ICP (induced coupled plasma), and elemental analysis.
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机译：介孔γ-Al2O3是用于商业催化应用的最广泛使用的催化剂载体之一。催化剂的性能在很大程度上取决于载体的质地，化学和物理性质的组合。孔径是必不可少的，因为每个催化体系都需要独特的孔径才能实现最佳的催化剂负载，扩散和选择性。另外，高表面积和大孔体积通常导致较高的催化剂负载量，这增加了催化反应位点的数量并减少了反应时间。因此，确定多孔载体的表面积和孔隙率对于成功设计和优化催化剂载体至关重要。此外，重要的是生产具有良好热稳定性的载体，因为由于高温下的烧结而导致的孔塌陷通常会导致催化剂失活。另外，控制催化剂酸度的能力使我们能够设计理想的酸位，以优化在不同催化剂应用中的产物选择性，活性和稳定性。本论文提出了一种简单的单釜，溶剂不足的合成方法。不使用模板的热稳定二氧化硅掺杂氧化铝（SDA）。使用XRD（X射线衍射），HTXRD（高温X射线衍射），SS NMR（固态核磁共振），TEM（透射电子显微镜），TGA（热重分析）和N2吸附技术来表征合成的SDA的结构，并了解增加的热稳定性的根源。所获得的SDA的表面积为160m2 / g，孔体积为0.99cm 3 / g，并且在1100℃下煅烧后的双峰孔径分布为23和52nm。与商业SDA相比，合成的SDA的表面积，孔体积和孔径分别高46％，155％和94％。分割图分数因子实验设计还用于获得有用的数学模型，以降低成本和减少实验次数来控制SDA的纹理特性。提出的定量模型可以预测最佳条件，以生产具有大于250 m2 / g的高表面积，大于1 cm3 / g的大孔体积以及大（40-60 nm）或中等（16-19 nm）孔径的SDA 。;在我的方法中，我通过更改合成方法中的制备变量（例如Si / Al比和煅烧温度）来控制酸位的形成。合成的SDA的总酸度浓度（布朗斯台德和刘易斯）使用氨温度程序，吡啶傅里叶变换红外光谱（FTIR）和MAS NMR确定。通过引入较高的Si与Al的摩尔比来增加总酸度浓度。此外，通过提高煅烧温度，同时保持高表面积，大孔隙率和γ-氧化铝载体的热稳定性，降低了总酸度。我还提出了各种醇铝（正己基铝（AH）铝）的优化合成方法。 ，苯酚铝（APh）和异丙醇铝（AIP）），收率很高（90-95％）。在0.1摩尔％的氯化汞催化剂存在下，使一摩尔铝与过量的醇反应。合成的烷氧基铝用作生产高表面积氧化铝催化剂载体的原料。通过1 H NMR，13 C NMR，27 Al NMR，gCOSY（2D核磁共振波谱），IR（红外光谱），XRD，ICP（感应耦合等离子体）和元素分析对铝醇盐和纳米氧化铝进行分析。
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