DFT Studies of the Selective C–O Hydrogenolysis and Ring-Opening of Biomass-Derived Tetrahydrofurfuryl Alcohol over Rh(111) surfaces

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• 作者：Jing Guan ; Jing Li ; Yifeng Yu ; Xindong Mu ; Aibing Chen
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：September 1, 2016
• 年：2016
• 卷：120
• 期：34
• 页码：19124-19134
• 全文大小：792K
• 年卷期：0
• ISSN：1932-7455

文摘

Tetrahydrofurfuryl alcohol (THFA) has been identified as a platform chemical of interest because of its production from biomass. It can be converted into valuable alcohols and ethers by selective hydrogenation/hydrogenolysis reaction over Rh-based metal catalysts. To better understand the chemistry of THFA, the reaction energies and the corresponding energy barriers of selective C–O bond hydrogenolysis and ring-opening of THFA on Rh(111) for the formation of 2-methyltetrahydrofuran (2-MeTHF), 1,5-pentanediol (1,5-PeD), and 1,2-pentanediol (1,2-PeD) were studied using density functional theory (DFT) calculations. The results indicate that starting from THFA to produce 2-MeTHF, the direct C–O bond cleavage of the CH₂OH group is not favored. Alternatively and more preferentially, the reaction occurs through the initial activation of C–H bond on the side chain, followed by dehydroxylation and hydrogenation. On the other hand, in the metal catalyzed ring-opening process of THFA to 1,5-PeD and 1,2-PeD, the first dehydrogenation of secondary CH–O or primary CH₂–O moiety in the ring decreases the barriers of the subsequent C–O bond dissociation. Moreover, the energy span theory shows that the ring-opening at the sterically less-hindered primary C–O bond exhibits a lower effective barrier than that for ring-opening at the more sterically hindered secondary C–O bond, as well as hydrogenolysis at the side CH₂OH chain, suggesting that the formation of 1,2-PeD is much kinetically favored than the formation of 1,5-PeD and 2-MeTHF. Our theoretical results give a good explanation for the experimental fact that 1,2-PeD was the dominant product observed on unprompted Rh/SiO₂.