氨合成球形催化剂的穆斯堡尔谱研究

本文用穆斯堡尔谱法对郑州大学开发的球形氨合成催化剂A₆C型和HAC型进行了研究。结果是不同工艺制成的氨合成熔铁催化剂基本相组成接近,但维氏体含量及助剂分布的均匀程度有较大的差异。球形A₆C催化剂较之配方接近的无定形A₆催化剂含有较多的维氏体,且Al⁺³进入晶格较多;A₆C与HAC两种球形催化剂,由于助剂含量不同,维氏体量与助剂分布状况的不同,引起催化剂还原性、活性及耐热性的差别。据此对球形催化剂的铁比(Fe⁺²/Fe⁺³)控制及使用条件提出一些看法。

THE MOSSBAUER SPECTROSCOPY RESEARCH OF SPHERICAL CATALYSTS OF AMMONIA SYNTHESIS

The mössbauer spectra of catalysts A₆C(spherical), HAC (spherical low-temperature catalyst) and A₆ (irregular), and promoterless samples were measured by the mössbauer spectrometer AME-50.The increasing of Wustite (Fe_1-xO) content and evenness of promoters distribution (more Al⁺³ has entered into Fe₃O₄ lattice) of spherical catalysts may be derived from the particular technology of preparation by which a rapid cooling was carried out in water.There is higher Wustite content of catalyst HAC than that of A₆C for the same iron ratio. It may be derived mainly from the different amounts of Al₂O₃ in the catalysts.More Wustite in catalyst results in easy reduction and high aetivi-ty, but less thermal stability. The even distribution of promoters counteracts the later weakness and ultimately the thermal stability rises in practice.The spherical catalysts ought to have their optimum iron ratios of Fe⁺²/Fe⁺³. The catalyst HAC should be prepared with smaller iron ratio than A₆C, and the catalyst HAC can be used very well in a wide range of temperature.