硝酸工厂铂合金催化网的铂耗

摘要

The platinum losses and ammonia consumption are main technical specifications for nitric acid production. The platinum losses from binary Pt-Rh and ternary Pt-Pd-Rh alloys, as well as from catalyst gauzes made of these materials, have been studied under laboratory and industrial conditions in atmospheric and medium pressure units in some nitric acid plants. The results showed that the rates of platinum loss and gauzes weight losses obey equations?W/S=Kt2/3and ΨΣ=K't2/3.The platinum loss(gram platinum per ton nitric acid, g/t) of Pt-12Pd-3.5Rh alloy gauzes is 0.044 g/t at atmospheric pressure and 0.121 g/t at medium pressure, the former being about 28% lower than that of Pt-4Pd-3.5Rh alloy gauzes(0.061 g/t), while the latter is about 21% lower than for that of Pt-5Rh and Pt-10Rh binary alloy gauzes(0.15~0.153 g/t). The ammonia consumption of Pt-12Pd-3.5Rh alloy gauzes is about 3%~7% lower than that of Pt-5Rh and Pt-10Rh binary alloys. Introducing palladium to the Pt-Rh alloys or increasing the palladium concentration in Pt-Pd-Rh alloys is clearly shown to decrease the gauze weight loss and the platinum loss. This is attributed to the passive action of palladium, which enriches the surface layer of the platinum alloys and catalyst gauzes, affecting the oxidation-reduction reaction of platinum.%铂耗和氨耗是硝酸生产的主要技术指标.在流动氧气氛模拟条件下,以及800~950℃的硝酸生产实际氨氧化环境中,Pt-Rh二元和Pt-Pd-Rh三元合金及其催化网的失重和铂耗均遵循相同的模式,即 ?W/S=Kt2/3与 ΨΣ=K't2/3.工厂实际测定数据表明,在常压氨氧化法生产硝酸过程中, Pt-12Pd-3.5Rh 合金催化网的铂耗为0.044 gPt/t(HNO3),比 Pt-4Pd-3.5Rh 合金催化网的铂耗(0.061 gPt/t(HNO3))低28%;在中压氨氧化法生产硝酸过程中,Pt-12Pd-3.5Rh 合金催化网的铂耗为0.121 gPt/t(HNO3),比Pt-5Rh和Pt-10Rh合金催化网的铂耗(0.15~0.153 gPt/t(HNO3))低21%,而其氨耗比后者降低3%~7%.研究结果证明,在Pt-Rh合金中添加钯或在Pt-Pd-Rh合金中增加钯含量明显降低催化合金的铂耗.