Dissociation of methyl nitrite is the first step during CO catalytic coupling to dimethyl oxalate followed by hydrogenation to ethyl glycol in a typical coal to liquid process. In this work

the first-principle calculations based on density functional theory were performed to explore the reaction mechanism for the non-catalytic dissociation of methyl nitrite in the gas phase and the catalytic dissociation of methyl nitrite on Pd(111) surface since palladium supported on alpha-alumina is the most effective catalyst for the coupling. For the non-catalytic case

the calculated results show that the CH

3

O-NO bond will break with a bond energy of 1.91 eV

and the produced CH

3

O radicals easily decompose to formaldehyde

while the further dissociation of formaldehyde in the gas phase is difficult due to the strong C-H bond. On the other hand

the catalytic dissociation of methyl nitrite on Pd(111) to the adsorbed CH

3

O andNOtakes place with a small energy barrier of 0.03 eV. The calculated activation energies along the proposed reaction pathways indicate that (i) at lowcoverage

a successive dehydrogenation of the adsorbed CH

3

O to CO and H is favored while (ii)

at high coverage

hydrogenation of CH

3

O to methanol and carbonylation of CH

3

O to methyl formate are more preferred. On the basis of the proposed reaction mechanism

two meaningfulways are proposed to suppress the dissociation of methyl nitrate during the CO catalytic coupling to dimethyl oxalate.