Stabilization of furanics to cyclic ketone building blocks in the vapor phase
Stabilization of furanics to cyclic ketone building blocks in the vapor phase
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DOI：
10.1016/j.apcatb.2019.04.079
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发表时间：
2019-10
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影响因子：
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通讯作者：
Taiwo Omotoso;Leidy V. Herrera;Tyler Vann;Nicholas M. Briggs;L. A. Gomez;L. Barrett;Donald G. Jones;T. Pham;Bin Wang;S. Crossley
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作者：
Taiwo Omotoso;Leidy V. Herrera;Tyler Vann;Nicholas M. Briggs;L. A. Gomez;L. Barrett;Donald G. Jones;T. Pham;Bin Wang;S. Crossley
生物质分解产生大量呋喃类化合物。这些物种的热稳定性和化学不稳定性导致胡敏素在缩合时形成。已知在缩合水相中，呋喃甲醛环重排生成2-环戊烯酮和环戊酮，但这需要在易于生成胡敏素的浓缩酸性介质中进行操作。高氢压通常用于抵消快速聚合反应，从而限制所产生的稳定的不饱和产物的产量。在本文中，我们报道了在负载型二氧化钛催化剂上，糠醛可以一步选择性地转化为2-环戊烯酮和环戊酮，催化剂上含有模型化合物和实际生物质衍生的蒸气。通过调节水的分压，可以调节TiO2负载的Ru和Pd催化剂上环重排和单键裂解的选择性。在没有浓缩酸的情况下，这些产物的形成也使反应环境的调节有利于不饱和酮的选择性形成，这些不饱和酮可能是有价值的二烯烃前体。催化剂中TiO2载体的加入抑制了单键C的氢解/脱羰反应，促进了环重排反应。讨论了选择性Cone-Bondo裂解和气相环重排活性中心的性质。
Furanics are produced in high abundance from the decomposition of biomass. The thermal and chemical instability of these species leads to the formation of humins upon condensation. The ring rearrangement of furfural to form 2-cyclopentenone and cyclopentanone is known to occur in the condensed aqueous phase, but this requires operation in condensed acidic media where humin formation readily occurs. High hydrogen pressures are typically used to offset rapid polymerization reactions, limiting the yields of stable unsaturated products that result. Here we report that furfural can be selectively converted to 2-cyclopentenone and cyclopentanone in a single step over supported TiO2catalysts with both model compounds and real biomass-derived streams in the vapor phase. Selectivity for ring rearrangement vs. Csingle bondO cleavage over TiO2supported Ru and Pd catalysts can be tuned by manipulating the water partial pressure. The formation of these products in the absence of a condensed acidic stream also enables the tuning of reaction environments to favor the selective formation of unsaturated ketones, which could be valuable diolefin precursors. The incorporation of a TiO2support in the catalysts tested leads to the suppression of Csingle bondC hydrogenolysis/decarbonylation and enhancement of ring rearrangement reactions. The nature of the active sites for selective Csingle bondO cleavage as well as vapor phase ring rearrangement are discussed.