Knowledge Bank

OH($\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\pi$)was detected in the dissociative adsorption of $H2O$ on polycrystalline Pt above $550\circ C$. The flux of thermally desorbed OH from Pt was measured as a function of Pt temperature, $H2O$ pressure, and added $H2,D2$ and $O2$ partial pressures. The observations support the following mechanism:\begin{eqnarray} && H_{2}O + 2^{} \rightarrow OH^{} + H^{} \ && HO^{} + ^{} \rightarrow H^{} + O^{}\ && HO^{} \rightarrow OH + ^{*},\end{eqnarray} Where $""\mathrm{<mrow\; data-mjx-texclass="ORD">\ast </mrow>}""$ represents an active catalyst site. The activation energy for reaction (3) was measured to be $30\pm 1$ kcal/mole.