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首页> 外文期刊>Chemistry: A European journal >highly effective sulfated zirconia nanocatalysts grown out of colloidal silica at high temperature
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highly effective sulfated zirconia nanocatalysts grown out of colloidal silica at high temperature

机译：胶态二氧化硅在高温下生长出的高效硫酸化氧化锆纳米催化剂

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摘要

A large surf ace-to-volume ratio is a prerequisite for highly effective catalysts. Making catalysts in the form of nanoparticles provides a good way to achieve the aim. However, agglomeration of nanoparticles during the preparation and utilization of nanocatalysts remains a formidable problem. Here, we present a novel approach in which nano units of catalysts are formed in the matrix of a colloidal carrier, with assistance of a cross-linking agent, and then grow out of the carrier upon calcination at high temperature. This ensures that the catalysts not only do not agglomerate, but also have a low cost and high catalytic efficiency due to the large surface-to-volume ratio and the absence of carbon deposition. The technique is demonstrated by the successful preparation of a binary nanocatalyst that consists of a silica nanoparticle core and a sulfated zirconia (SZ) nanocrystal shell (JML-1). The synthesis was achieved by converting sulfated zirconia (SZ) and silica solutions into a composite gel by means of sol-gel processing in the presence of triethoxysilane as the cross-linking agent, followed by heating at 50degreesC and calcining at 550degreesC. Relative to other catalysts, such as pure SZ, non-nano-dispersed SZ over silica (SZ/SiO2), and zeolites Y, Beta, and ZSM-5, JML-1 exhibits superior catalytic activity in many reactions. For example, the activity of JML-1 in the production of gasoline by alkylation of 1-butene with isobutene remained at 95% or higher after 20 h of reaction and was over 90% after being regenerated five times. In sharp contrast, SZ and SZ/ SiO2 give a high activity only for 2 h and the initial activity of zeolites Beta and ZSM-5 are about 88 and 60%, respectively. These findings demonstrate that non-agglomerated nanoparticles anchored onto a carrier surface can be prepared and the technique provides a versatile route to new highly effective nanocatalyst systems.
机译：大的表面体积比是高效催化剂的先决条件。以纳米颗粒形式制备催化剂提供了实现该目标的好方法。然而，在纳米催化剂的制备和利用过程中纳米颗粒的团聚仍然是一个巨大的问题。在这里，我们提出了一种新颖的方法，其中在交联剂的帮助下，在胶体载体的基质中形成催化剂的纳米单元，然后在高温下煅烧而从载体中长出来。这确保了催化剂不仅附聚，而且由于大的体积比和没有碳沉积而具有低成本和高催化效率。通过成功制备由二氧化硅纳米颗粒核心和硫酸化氧化锆（SZ）纳米晶体壳（JML-1）组成的二元纳米催化剂，证明了该技术。通过在三乙氧基硅烷作为交联剂的存在下，通过溶胶-凝胶法将硫酸化的氧化锆（SZ）和二氧化硅溶液转化为复合凝胶，然后在50°C加热并在550°C煅烧，从而实现了合成。相对于其他催化剂，例如纯SZ，二氧化硅上的非纳米分散SZ（SZ / SiO2）和沸石Y，Beta和ZSM-5，JML-1在许多反应中均显示出优异的催化活性。例如，通过1-丁烯与异丁烯的烷基化反应生产汽油时，JML-1的活性在反应20小时后保持在95％或更高，而再生5次后则超过90％。与之形成鲜明对比的是，SZ和SZ / SiO2仅在2小时内具有高活性，Beta和ZSM-5沸石的初始活性分别约为88％和60％。这些发现表明，可以制备锚定在载体表面上的非团聚纳米颗粒，并且该技术提供了通往新型高效纳米催化剂系统的通用途径。

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