METHANOL ADSORPTION AND DECOMPOSITION ON (2 X-1) PT(110) - ENHANCED STABILITY OF THE METHOXY INTERMEDIATE ON A STEPPED SURFACE

The decomposition of methanol on (2 x 1)Pt(110) is examined using TPD and EELS. It is found that the methanol adsorbs molecularly at 100 K. Some of the methanol desorbs upon heating to 125-200 K and some decomposes to yield methoxy (mu-OCH3). Upon further heating to 215-275 K some of the methoxy recombines with hydrogen to yield methanol and some decomposes to yield CO and hydrogen. There is also the hint of a transient intermediate at 220 K which has characteristics consistent with formaldehyde (CH2 = O(ad)) or a formyl (-CH = O(ad)) species. A comparison with the previous literature indicates that the decomposition of the methoxy intermediate is much slower on (2 x 1)Pt(110) than on Pt(111) even though there are (111) terraces on (2 x 1)Pt(110). Thus, this paper demonstrates for the first time that steps can decrease the rate of a simple decomposition reaction.