ABSTRACT

The development of materials that can exhibit thermal resistance at very high temperatures, thus allowing them to be applied as catalysts and thermal insulators, amongst other possible uses, is a research subject of great interest. This is the case for hexaaluminates, a class of hexagonal aluminate compounds with a unique structure that are stable at very high temperatures up to 1600°C and exhibit exceptional resistance to sintering and thermal shock, thus making them attractive catalysts for high-temperature applications. In this review, the structure of hexaaluminates is presented first. The most recent advances in synthetic methods (sol-gel, reverse microemulsion, hydrothermal synthesis, carbon-templating, solution combustion synthesis, and freeze-drying methods) are discussed subsequently, with the aim of maximizing textural properties and including in their structure metals known to be active in catalytic applications, such as combustion of CH₄, partial oxidation, and dry reforming of CH₄ to produce synthetic gas, and the decomposition of N₂O. Finally, other applications, such as their function as a thermal barrier, are also addressed.

摘要

开发能够在非常高的温度下表现出耐热性的材料，从而使它们能够用作催化剂和热绝缘体，以及其他可能的用途，是一个非常有趣的研究课题。六铝酸盐就是这种情况，这是一类具有独特结构的六方铝酸盐化合物，可在高达 1600°C 的高温下保持稳定，并表现出卓越的抗烧结和热冲击性，因此使其成为高温应用中极具吸引力的催化剂。在这篇综述中，首先介绍了六铝酸盐的结构。随后讨论了合成方法（溶胶-凝胶、反相微乳液、水热合成、碳模板、溶液燃烧合成和冷冻干燥方法）的最新进展，_{参照图4 ，CH 4}的部分氧化和干重重整以产生合成气，以及N ₂ O的分解。最后，还涉及其他应用，例如它们作为热障的功能。