J.R. S. answered 12/17/20
Ph.D. in Biochemistry--University Professor--Chemistry Tutor
The greatest yield of CH3OH is when the temperature is the lowest and the pressure is the highest (200º and 400 atm). So, one might suggest that to increase the yield you reduce the temperature and increase the pressure.
Not knowing the exact reaction that is taking place, it's difficult to be very specific or to fully explain this answer, but apparently the reaction is exothermic since % yield decreases as the temperature increases. Further, it appears that there are more moles of gas on the reactant side of the reaction (whatever that reaction is) than on the product side. Thus, according to LeChatelier, increasing the pressure would favor product formation.