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作为催化剂的一种常用载体,γ-Al_2O_3的纯度常表现出对催化活性有重要影响.以稀土复合氧化物催化剂La_(0.7)Sr_(0.3)MnO_3/γ-Al_2O_3对CO氧化反应为例,王其武等发现,载体γ-Al_2O_3经用酸预处理后变得洁白而质轻,与未经处理的载体相比,在185℃时CO在催化剂上的转化率由50％提高到90％.朱国平也指出此种预处理的重要性.工业γ-氧化铝样品中经常含有微量铁,我们的实验表明,这部分杂质经反复酸洗,可以有所减少,但难以全部除掉.复盖在γ-氧化铝表面上的铁,可能是影响催化剂活性的重要因素. 为了鉴别γ-氧化铝样品中的铁杂质,我们曾先后用XRD和Mossbauer谱法进行测定,
As a common carrier of the catalyst, the purity of γ-Al 2 O 3 often shows an important influence on the catalytic activity. Taking the rare earth composite oxide catalyst La_ (0.7) Sr_ (0.3) MnO_3 / γ-Al_2O_3 as an example, Found that the carrier γ-Al 2 O 3 after the acid pretreatment became white and lightweight, compared with the untreated carrier, the conversion of CO on the catalyst at 185 ° C increased from 50% to 90%. The importance of such pretreatment is pointed out.It is often found that industrial γ-alumina samples contain a trace amount of iron, and our experiments show that this part of the impurities can be reduced by repeated pickling but can not be completely removed, Iron on the alumina surface may be an important factor affecting the activity of the catalyst.In order to identify the iron impurities in the γ-alumina sample, we have been determined by XRD and Mossbauer spectroscopy,