Surface chemistry of 2-propanol on TiO2(110):: Low- and high-temperature dehydration, isotope effects, and influence of local surface structure

Dosed on rutile TiO2(110) at 100 K, the thermal chemistry of 2-propanol in three formsC(3)H(7)OH, C3D7OD, and C(3)H(7)ODwas characterized using temperature-programmed desorption. Only 2-propanol, propene, and water desorb with no evidence for acetone. The propene forms and desorbs by two paths, a heretofore unreported low-temperature path extending from 300 to 450 K and, concurring with prior work, a high-temperature path peaking between 570 and 580 K. Both paths exhibit isotope effects. The high-temperature path is interpreted in terms of decomposition of 2-propoxy species located on bridging oxygen atom rows. The low-temperature path is attributed to 2-propanol dehydration on undercoordinated Ti4+ ions of the Ti4+ rows. The low-temperature path characteristics vary with the long-range order and bridge-bonded oxygen atom vacancy concentration.