Surface Chemistry of 2-Propanol on TiO₂(110):  Low- and High-Temperature Dehydration, Isotope Effects, and Influence of Local Surface Structure

Abstract

Dosed on rutile TiO 2 (110) at 100 K, the thermal chemistry of 2-propanol in three formssC 3 H 7 OH, C 3 D 7 OD, and C 3 H 7 ODswas 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 Ti 4+ ions of the Ti 4+ rows. The low-temperature path characteristics vary with the long-range order and bridge-bonded oxygen atom vacancy concentration.

Energetic and Electronic Properties of P Doping at the Rutile TiO2 (110) Surface from First Principles

“…The atoms in the bottom layer were fixed to their optimized bulk positions in order to simulate the presence of the bulk underneath. This configuration has been shown to minimize well-known energy oscillations as a function of the number of layers (even-odd) [30], and has proven to agree well with recent experimental studies [31]. The relaxed Ti-O bond lengths at or near the pure rutile TiO 2 surface are listed in Table 1 as well as experimental data [31] and previous theoretical calculated results [32].…”

Inductive Effect of Alkyl Chains on Alcohol Dehydration at Bridge-bonded Oxygen Vacancies of TiO2(110)

“…For alcohols, it is well-established that their dissociation on bridge-bonded oxygen vacancies (BBO V 's) of a prototypical TiO 2 (110) surface proceeds via heterolytic cleavage of the RO-H bond [4,5]. The resulting intermediates are alkoxide (RO) that fills the BBO V and a proton that binds to a neighboring bridge-bonded oxygen (BBO) anion [6][7][8][9][10]. Except for methoxide, these alkoxides dehydrate at elevated temperatures (well above 300 K) via b-hydride elimination to form alkenes [6,9,10].…”

“…The resulting intermediates are alkoxide (RO) that fills the BBO V and a proton that binds to a neighboring bridge-bonded oxygen (BBO) anion [6][7][8][9][10]. Except for methoxide, these alkoxides dehydrate at elevated temperatures (well above 300 K) via b-hydride elimination to form alkenes [6,9,10]. In some cases, the dehydration is accompanied by a minority dehydrogenation channel yielding aldehydes [6][7][8][9].…”

“…Except for methoxide, these alkoxides dehydrate at elevated temperatures (well above 300 K) via b-hydride elimination to form alkenes [6,9,10]. In some cases, the dehydration is accompanied by a minority dehydrogenation channel yielding aldehydes [6][7][8][9].…”

Photoemission Study on the Adsorption of Ethanol on Chemically Modified TiO2(001) Surfaces

“…3 For this reason, intense research effort has been made to understand the origin of the TiO 2 -catalyzed reactions of simple molecules such as H 2 O, 4-6 O 2 , 7-10 alcohols, [11][12][13] and aldehydes.…”