摘要
在B3LYP/ 6 311G(d)水平上研究了NiO催化的HCOOH→CO +H2 O和HCOOH→CO2 +H2 两个反应的单态势能曲线 .结果表明 ,在NiO上甲酸容易解离吸附形成甲酸盐HONiOCOH ,甲酸盐的分解是上述两个反应的速率决定步骤 ,这两个反应的活化能大致相当 .在脱水反应中 ,HCOOH和NiO之间存在着氧交换 ,但脱氢反应中不存在氧交换 .甲酸盐发生脱氢反应还是脱水反应取决于甲酸盐是用其羟基中的H还是用O去进攻甲酸根中的H原子 .
The catalytic decomposition of formic acid on NiO(111) has been investigated but its mechanism is not affirmed. By using NiO “molecule” to simulate NiO crystal, singlet potential energy curves for the reactions of HCOOH→CO+H 2O and HCOOH→CO 2+H 2 catalyzed by NiO were studied at B3LYP/6-311G(d) level by the all-optimum method in this paper. The intrinsic reaction coordinate confirmation for two transitions, TS2 and TS3, was also given. The results show that formic acid adsorbs dissociatively on NiO and becomes formate HONiOCOH. The decomposition of formate is the rate-determining step for both the reactions, and the activation energies of the two reactions are almost the same. In the dehydration reaction, there is O-interchange between HCOOH and NiO, while in the dehydrogenation, there is no O-interchange, which is consistent with the experimental results. Both the decomposition paths undergo a cyclic transition state. When HONiOCOH uses the O atom of hydroxyl (OH) to attack the H atom of OCOH, the dehydration producing CO and H 2O occurs; when HONiOCOH uses the H atom of hydroxyl (OH) to attack the H atom of OCOH, the dehydrogenation producing CO 2 and H 2 occurs.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第2期129-132,共4页
基金
国家自然科学基金资助项目 ( 2 9973 0 0 6)
结构化学国家重点实验室基金资助项目 (K990 3 2 )
