Catalytic Decomposition of Methanol over Nickel Wire

Abstract

The kinetic studies of the decomposition of methanol have been undertaken under pressures of up to 20 mmHg and at temperatures between 300 and 430°C. The initial rate (r0) of decomposition which turns methanol into carbon monoxide and hydrogen was found to be expressed by the equation, r0=aPm⁄(1+b\sqrtPm)2 where Pm is the initial pressure of methanol and where a and b are constants. The addition of carbon monoxide to the reactant was found to depress the rate of reaction, while a slight promotion was observed upon the addition of hydrogen to the system. On the other hand, when the kinetics of the decomposition of formaldehyde, which was regarded as the intermediate product in the methanol decomposition, was studied, it was found that formaldehyde decomposed to cabon monoxide and hydrogen, and that the rate was much larger than that of methanol decomposition. On the basis of these results and the exchange reaction of methanol with deuterium, the processes of methanol decomposition were discussed in detail and a possible mechanism of reaction was proposed in which the surface reaction between the adsorbed methoxy radical and the hydrogen atom, both produced by the dissociative adsorption of methanol, is the rate-determining step of the reaction.