Methanol is synthesized commercially from CO and H2 by the reaction, CO + 2H2 --
ID: 1848436 • Letter: M
Question
Methanol is synthesized commercially from CO and H2 by the reaction, CO + 2H2 ----> CH3OH over a Cu/ZnO catalyst at 350 C at 50-100 atm. The standard-state thermodynamic data on this reaction are deltaHR,298 = -90.64 kJ/mole and deltaGR,298 = -24.2 kJ/mole.a) What is the equilibrium conversion of a stoichiometric mixture of CO and H2 to methanol at 298 K at 1 atm?
b) Assuming deltaHR independent of T, what are Keq and the equilibrium conversion at 1 atm and 350 C?
c) The actual value of Keq at 350 C is 1.94*10^-4. How large is the error assuming constant deltaHR?
d) At what pressure will the equilibrium conversion be 50% at 350 C?
Explanation / Answer
CO(g) + 2 H2(g) ?? CH3OH(g) => K = x(CH3OH) / [ x(CO) · (x(H2))² ] x(CH3OH) = N(CH3OH) / (N(CH3OH) + N(CO) · N(H2) ) = 0.0784mol / ( 0.0784 mol + 0.181mol + 0.225mol ) = 0.16185 x(CO) = N(CO) / (N(CH3OH) + N(CO) · N(H2) ) = 0.181mol / ( 0.0784 mol + 0.181mol + 0.225mol ) = 0.37366 x(H2) = N(H2) / (N(CH3OH) + N(CO) · N(H2) ) = 0.225mol / ( 0.0784 mol + 0.181mol + 0.225mol ) = 0.46449 => K = 0.16185 / [ 0.37366 · 0.46449² ] = 2.008