We note from this reforming reaction that for every mol of CO produced,
three moles of H2 are produced, but the methanol synthesis reaction (Eq. 9.3)
requires only two moles of hydrogen for every mole of carbon monoxide. Thus,
there is an extra hydrogen molecule for every mol of methanol. In such a situation,
carbon dioxide, if available, may be used in the following reaction to
produce an additional methanol molecule utilizing the excess hydrogen