Abstract

The xerogels in the system 0.88 mol % ZrO₂–0.12 mol % CeO₂ were obtained by the method of coprecipitation in a neutral (pH 7) and slightly alkaline (pH 9) medium under the influence of ultrasound with the size of the agglomerates of 70–230 nm. It is shown that the coprecipitation of hydroxides of zirconium and cerium at pH 9 with the use of ultrasonic treatment facilitates the formation of primary crystalline particles in the xerogel, whose size is ~ 5 nm, whereas the xerogel synthesized in a neutral environment consists only of the X-ray amorphous phase. The effect of pH precipitation on deposition processes of dehydration of the xerogels and crystallization of the solid solution based on zirconia oxide in the metastable pseudocubic modification (с'-ZrO₂) was discovered. It was found that, in the temperature range of 500–800°C, there is a phase transition с'-ZrO₂ → t-ZrO₂; the size of the crystallites of the formed tetragonal solid solutions is 8 and 11 nm. The dispersion properties and characteristics of the pore structure of the powders of the solid solution Zr_0.88Ce_0.12O₂ were investigated by the method of low-temperature nitrogen adsorption. It is determined that the specific surface area of t-ZrO₂ samples obtained after firing at 800°C is 117 and 178 m²/g, the total pore volume reaches 0.300–0.325 cm³/g, and the pore size distribution is monomodal and is in the range of 2–8 nm. The effect of thermal “aging” at a temperature of 800°C (40 h) on the structure and dispersion of the solid solution t-ZrO₂ powders was studied.

中文翻译：

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Zr 0.88 Ce 0.12 O 2的固溶分散介孔粉体的甲烷转化合成气催化剂载体的合成。

摘要

在超声波的影响下，在中性（pH 7）和弱碱性（pH 9）的介质中，通过共沉淀的方法，通过共沉淀的方法获得了0.88 mol％ZrO ₂ –0.12 mol％CeO ₂体系中的干凝胶。 70–230 nm。结果表明，通过超声处理，在pH 9时锆和铈的氢氧化物共沉淀有助于在干凝胶中形成粒径约为5 nm的初生结晶颗粒，而在中性环境中合成的干凝胶仅由X射线非晶相。pH值沉淀对干凝胶的脱水和固溶体的结晶的沉积过程基于在亚稳仿立方体改性氧化锆氧化物（с'-的ZrO效果₂） 被发现。我们发现，在温度范围500-800℃，有相变с'-的ZrO ₂ →叔的ZrO ₂ ; 所形成的四方固溶体的微晶尺寸为8和11nm。采用低温氮吸附法研究了固溶体Zr _0.88 Ce _0.12 O ₂粉末的分散性能和孔结构特征。经测定，在800℃焙烧后得到的t-ZrO ₂样品的比表面积为117和178 m ² / g，总孔体积为0.300–0.325 cm ³/ g，孔径分布是单峰的，在2-8 nm范围内。研究了温度为800℃（40小时）时热“老化”对t-ZrO ₂固溶体粉末结构和分散性的影响。