I need to generate pure gas from a gas stream which is free of $\ce{SO2}$/$\ce{NO}$/$\ce{NO2}.$ The air is already pretreated by activated carbon and purafil. However, I can't find any solution for removing trace level of this pollutants. I find that many solutions of capturing for large scale like flue gas. However, it is not suitable for trace level (1–10 ppb).
I know $\ce{O3}$ can react with $\ce{NO}$ to $\ce{NO2}$. However, as I mentioned, I need the gas stream free of $\ce{NO}$ and $\ce{NO2}$ simultaneously. So, converting $\ce{NO}$ to $\ce{NO2}$ is not the answer.