Propylene deep oxidation on the Pt(111) surface: temperature programmed studies over extended coverage ranges

CO as a Promoting Spectator Species of CxHy Conversions Relevant for Fischer–Tropsch Chain Growth on Cobalt: Evidence from Temperature-Programmed Reaction and Reflection Absorption Infrared Spectroscopy

“…After losing one more hydrogen at ∼400 K, the last bit of hydrogen is lost between 450 and 630 K with the broad desorption peak being indicative of the formation of "polymeric" carbon in this temperature window. 21,22 As the final temperature reached in the TPRS experiment is high enough to completely dehydrogenate the C x H y adsorbates the total H 2 production can be used to quantify the amount of precursor molecules that was decomposed. Quantitative analysis of the amount of H 2 desorbed after complete dehydrogenation of the propene and but-1-ene precursor shows that 0.15−0.16 ML of the precursor molecule decomposes during heating of the alkene-saturated surface in a vacuum.…”

“…The H 2 desorption peak at 355 K accounts for the loss of four more hydrogens per precursor molecule, and it is attributed to the dehydrogenation of the -C 2 H 5 group to produce an intermediate with C 4 H 2 stoichiometry. After losing one more hydrogen at ∼400 K, the last bit of hydrogen is lost between 450 and 630 K with the broad desorption peak being indicative of the formation of “polymeric” carbon in this temperature window. , …”

“…Similar to the longer C x H y , the last bit of hydrogen desorbs in a broad temperature window characteristic of the slow dehydrogenation of polymeric forms of surface carbon. 21,22 The XPS measurements shown in Figure 5(b) indeed confirm the presence of "polymeric" carbon at a binding energy of ∼284.5 eV 20 after heating to 630 K in the presence of CO in contrast to the 283 eV peak due to atomic carbon that is found after heating in a vacuum.…”

Comparisons of propylene and propyne catalytic oxidation on a 100 Å Pt/Al2O3 thin film using in situ soft X-ray fluorescence methods

“…The thin film TP-FYNES spectrum begins with a drop in carbon concentration over the 200-275 K range. Propylene desorption has been observed in this temperature range during TPD experiments on the Pt(1 1 1) surface [8]. On the Pt thin film surface this drop from 5.5 · 10 14 to 2.0 · 10 14 carbon atoms/cm 2 indicates that 63% of the propylene desorbs between 230 and 270 K. On the Pt (1 1 1) served.…”

“…Recently, calorimetric sensing of C 3 hydrocarbons has been proposed as part of advanced emission control strategies for automobile exhaust streams [1]. Despite the importance of hydrocarbon oxidation, molecular mechanisms of catalytic oxidation processes on metal surfaces are just beginning to emerge in UHV [2][3][4][5][6][7][8][9][10][11], and have only recently been examined by our group in pressures of flowing oxygen [12][13][14][15][16][17].…”