$\mathrm{CO}_2+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{H}_2 \mathrm{CO}_3$
$\mathrm{C}+\mathrm{H}_2 \mathrm{O}($ steam $) \rightarrow \mathrm{CO}+\mathrm{H}_2$
$\left.\begin{array}{l}\mathrm{CH}_4+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{CO}+3 \mathrm{H}_2 \\ \mathrm{C}_3 \mathrm{H}_8+\mathrm{H}_2 \mathrm{O} \rightarrow 3 \mathrm{CO}+\mathrm{H}_2\end{array}\right] \begin{gathered}\text { both reactions are carried out at } \\ 1270 \mathrm{~K} \text { temp. with } \mathrm{Ni} \text { catalyst }\end{gathered}$
Thus $\mathrm{CO}_2$ does not produce CO .