論文 - 山方　啓

In situ observation of the exchange reaction of formate with molecular formic acid on Ni(110) 査読

A Yamakata, J Kubota, JN Kondo, C Hirose, K Domen, F Wakabayashi, K Tamaru

JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL   141 ( 1-3 )   73 - 82   1999年5月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The exchange reaction of adsorbed formate on Ni(110) with formic acid in gas phase was studied by the time-resolved infrared reflection absorption spectroscopy (TR-IRAS). It was found that the pre-adsorbed deuterated formate (DCOO(a)) was changed to HCOO(a) in the presence of HCOOD(g) at the temperature region from 240 to 300 K. In such a temperature region, the formate was stable on the surface in vacuum and the decomposition of formate was not observed. It was suggested that the pre-adsorbed DCOO(a) was desorbed as DCOOD accepting deuterium atom from HCOOD. The activation energy of the exchange reaction was estimated to be 23 +/- 2 kJ mol(-1). The reaction order with respect to formic acid pressure was 0.3 +/- 0.1, while that as to the coverage of DCOO(a), was unity. Taking into account all the experimental results, the exchange of pre-adsorbed formate with post-exposed formic acid is suggested to proceed via forming a hydrogen-bonded intermediate complex on the formate's site, because all the sites were already occupied by formate. The small activation energy of the exchange reaction is discussed on the basis of 'adsorption-assisted desorption'. We propose that when desorption and adsorption are coupled, the activation energy of the exchange reaction should be described as a sum of the potential energy profiles of a desorbing and an adsorbing molecule. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S1381-1169(98)00251-9

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Exchange reaction of adsorbed formate with gaseous formic acid on Ni(110) studied by time-resolved Fourier transform infrared reflection absorption spectroscopy 査読

A Yamakata, J Kubota, JN Kondo, C Hirose, K Domen, F Wakabayashi, K Tamaru

JOURNAL OF PHYSICAL CHEMISTRY B   102 ( 22 )   4401 - 4403   1998年5月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The dynamic behavior of adsorbed formate on Ni(110) in the presence of gaseous formic acid was studied by time-resolved infrared reflection absorption spectroscopy. The preadsorbed formate (DCOO(a)) was replaced by the postexposed formic acid (HCOOD) to form HCOO(a) on Ni(110) in the temperature region between 230 and 300 K, where the formate was stable under vacuum and no decomposition of formate was observed. It was confirmed that the preadsorbed DCOO(a) desorbed as DCOOD accompanied by formation of HCOO(a) via the deuterium atom transfer from HCOOD.

DOI： 10.1021/jp981192b

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時間分解赤外反射吸収分光法によるNi(110)表面に吸着したフォルメートと気相に導入したギ酸の交換反応 査読

山方 啓, 久保田 純, 野村 淳子, 廣瀬 千秋, 堂免 一成, 若林 文高

表面科学   19 ( 7 )   441 - 445   1998年

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出版者・発行元：The Surface Science Society of Japan  

The exchange reaction of formate (DCOO(a)) with gaseous formic acid (HCOOD) on Ni(110) was investigated below the decomposition temperature of formate (340 K) by means of time-resolved infrared reflection absorption spectroscopy (TR-IRAS). When HCOOD gas was admitted on DCOO(a)-covered Ni(110) at 300 K, the pre-adsorbed DCOO(a) was replaced by HCOO(a). Similar replacement was also observed by introducing H<SUP>12</SUP> COOH gas onto H-<SUP>13</SUP>COO(a)-covered Ni(110). In such a temperature region from 240 to 300 K, no decomposition of formate was observed. Thus it was confirmed that those pre-adsorbed formate desorbed as formic acid accompanied by the transfer of hydrogen (deuterium) atom from post-introduced formic acid. The kinetics of the exchange reaction is investigated and the mechanism of that is also discussed.

DOI： 10.1380/jsssj.19.441

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赤外反射吸収分光法によるNi(110)上に吸着した ギ酸の分解過程の観察 査読

山方 啓, 久保田 純, 野村 淳子, 廣瀬 千秋, 堂免 一成, 若林 文高

表面科学   18 ( 7 )   417 - 423   1997年7月

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記述言語：日本語   出版者・発行元：日本表面科学会  

The decomposition of the surface formate on Ni(110) was studied by temperature programmed desorption (TPD) and timeresolved infrared reflection absorption spectroscopy (TR-IRAS). It was observed that dehydration proceeded simultaneously with dehydrogenation. The rate-determining step of dehydration was found to be the C-H bond cleavage of formate as is the case of dehydrogenation by analysis of the kinetic isotope effect using HCOO(a) and DCOO(a). These results suggest that the rate-determining steps of dehydration and dehydrogenation are common. We propose a mechanism in which the CO₂(a) species formed via the C-H bond cleavage of formate acts as the intermediate not only for dehydrogenation but also for dehydration; dehydration takes place by dissociation of the C-O bond of CO₂(a).

DOI： 10.1380/jsssj.18.417

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In situ observation of the dehydration of formate on Ni(110) 査読

A Yamakata, J Kubota, JN Kondo, C Hirose, K Domen, F Wakabayashi

JOURNAL OF PHYSICAL CHEMISTRY B   101 ( 26 )   5177 - 5181   1997年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The dehydration of formate adsorbed on Ni(110) has been studied by the direct observation of the CO(a) produced on the surface by means of time-resolved infrared reflection absorption spectroscopy (TR-IRAS). By the quantitative analysis of the temperature-programmed desorption and TR-IRAS results, it was found that the dehydration proceeds simultaneously with the dehydrogenation. The primary kinetic isotope effect (k(H)/k(D)) using HCOO(a) and DCOO(a) was observed not only in the dehydrogenation but also in the dehydration (k(H)/k(D) = 3.3 at 300 K). This result suggests that the rate-determining step (RDS) is the C-H bond dissociation in both processes. These suggestions let us propose a possible mechanism of the dehydration of formate on Ni(110); the RDS of the dehydration is the C-H bond dissociation which is the same as that of the dehydrogenation, and the produced CO2(a) is the precursor of the production of CO(a) and O(a).

DOI： 10.1021/jp9703418

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Isotope exchange reaction of formate with molecular hydrogen on Ni(110) by IRAS 査読

A Yamakata, J Kubota, JN Kondo, K Domen, C Hirose

JOURNAL OF PHYSICAL CHEMISTRY   100 ( 46 )   18177 - 18182   1996年11月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Kinetics of the CH/CD isotope exchange reaction of formate (HCOO(a)/DCOO(a)) on Ni(110) with gaseous D-2/H-2 was investigated below the decomposition temperature (360 K) by infrared reflection absorption spectroscopy (IRAS). The apparent activation energies of HCOO(a) --> DCOO (a) and DCOO(a) --> HCOO(a) reactions were derived as 52 +/- 5 and 58 +/- 5 kJ . mol(-1), respectively. A half-order dependence of the reaction rate on hydrogen pressure was observed, suggesting that the rate-determining step was the reaction of the adsorbed formate with reversibly adsorbed hydrogen atom. The reaction of HCOO(a) with D-2 was 2.1 +/- 0.3 times faster than that of DCOO(a) with H-2 at 300 K, and the origin of the isotope effect is discussed.

DOI： 10.1021/jp9611986

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SFG Study of Formic Acid on a Pt(110)-(1ｘ2) Surface 査読

WATANABE N, IWATSU K, YAMAKATA Akira, OHTANI T, KUBOTA Jun, KONDO J. N, WADA A, DOMEN Kazunari, HIROSE Chiaki

Surf Sci   357 ( 1-3 )   651 - 655   1996年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/0039-6028(96)00239-7

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