一氧化碳对氢气中脱氧的影响

工业上制备得到的氢气中通常含有万分之几至千分之几体积的氧组分,需将氢气深度纯化后才能得到高纯度的氢,即氧含量要低达百万分之几。将氢气气体中的氧深度净化,一般采用催化氧化的方法,选择Al2O3作载体负载的Pd、Pt等贵金属催化剂,在常温下就可将氧脱除到3×10-6～5×10-6甚至1×10-6以下。但是对含有一氧化碳的氢气在常温下要将氢气中氧含量脱至3×10-6～5×10-6就难以做到。本文考察了氢气中有一氧化碳存在时,对Pd/Al2O3脱氧催化剂在不同温度和空速下脱除氧的影响。在反应温度150～170℃、空速5000h-1的实验条件下,氢气中氧含量从0.4%降低到(2～3)×10-6。温度继续升高时残氧量变化不大,当温度超过200℃时,CO会在高温下歧化而结炭,因此反应温度不应超过200℃。

Influence of Carbon Monoxide on Deoxidation in Hydrogen

In industrial hydrogen, there is often a small quantity of oxygen that needs eliminate to get high pure hydrogen. Catalytic oxidation with the catalysts of Pd or Pt supported on Al_2O_3 is employed for deeply removing the oxygen in hydrogen, and it can generally remove oxygen to a level of 3×10~(-6)～5×10~(-6), even below 1×10~(-6) under normal temperature. However, to the hydrogen contained carbon monoxide, it is difficult to remove oxygen to this level at normal temperature. Effect of temperature and space velocity on deoxidation of the hydrogen containing carbon monoxide over Pd/Al_2O_3 catalyst has been observed in this article. Oxygen content in hydrogen can reduce from 0.4% to 2×10~(-6)～3×10~(-6) in the reaction temperature range of 150～170℃ and at the space velocity of 5000h~(-1). Raising the temperature again, the residual oxygen has little change. When the temperature is over 200℃, the carbon deposition will occur due to disproportionation reaction of carbon monoxide, so it should be below 200℃.