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Mechanisms for High Selectivity in the Hydrodeoxygenation of 5-Hydroxymethylfurfural over PtCo Nanocrystals
ACS Catalysis ( IF 11.3 ) Pub Date : 2016-05-31 00:00:00 , DOI: 10.1021/acscatal.6b00750
Jing Luo 1 , Hongseok Yun 2 , Alexander V. Mironenko 3 , Konstantinos Goulas 3 , Jennifer D. Lee 2 , Matteo Monai 4 , Cong Wang 1 , Vassili Vorotnikov 3 , Christopher B. Murray 2 , Dionisios G. Vlachos 3 , Paolo Fornasiero 4 , Raymond J. Gorte 1
Affiliation  

Carbon-supported, Pt and PtCo nanocrystals (NCs) with controlled size and composition were synthesized and examined for hydrodeoxygenation (HDO) of 5-hydroxymethylfurfural (HMF). Experiments in a continuous flow reactor with 1-propanol solvent, at 120 to 160 °C and 33 bar H2, demonstrated that reaction is sequential on both Pt and PtCo alloys, with 2,5-dimethylfuran (DMF) formed as an intermediate product. However, the reaction of DMF is greatly suppressed on the alloys, such that a Pt3Co2 catalyst achieved DMF yields as high as 98%. XRD and XAS data indicate that the Pt3Co2 catalyst consists of a Pt-rich core and a Co oxide surface monolayer whose structure differs substantially from that of bulk Co oxide. Density functional theory (DFT) calculations reveal that the oxide monolayer interacts weakly with the furan ring to prevent side reactions, including overhydrogenation and ring opening, while providing sites for effective HDO to the desired product, DMF. We demonstrate that control over metal nanoparticle size and composition, along with operating conditions, is crucial to achieving good performance and stability. Implications of this mechanism for other reactions and catalysts are discussed.

中文翻译:

PtCo纳米晶上5-羟基甲基糠醛加氢脱氧的高选择性机理

合成了具有受控大小和组成的碳载Pt和PtCo纳米晶体(NCs),并检查了5-羟甲基糠醛(HMF)的加氢脱氧(HDO)。在具有1-丙醇溶剂的连续流动反应器中于120至160°C和33 bar H 2进行的实验表明,在Pt和PtCo合金上反应都是顺序进行的,形成了2,5-二甲基呋喃(DMF)作为中间产物。然而,DMF在合金上的反应被极大地抑制,使得Pt 3 Co 2催化剂实现了高达98%的DMF收率。XRD和XAS数据表明Pt 3 Co 2催化剂由富Pt核和Co氧化物表面单层组成,其结构与块状Co氧化物有本质区别。密度泛函理论(DFT)的计算表明,氧化物单层与呋喃环之间的相互作用较弱,可以防止副反应(包括过度氢化和开环),同时为所需产物DMF提供有效的HDO位点。我们证明,控制金属纳米粒子的大小和组成以及操作条件对于实现良好的性能和稳定性至关重要。讨论了该机理对其他反应和催化剂的影响。
更新日期:2016-05-31
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