One-pot direct conversion of levulinic acid into high-yield valeric acid over a highly stable bimetallic Nb-Cu/Zr-doped porous silica catalyst,Green Chemistry

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One-pot direct conversion of levulinic acid into high-yield valeric acid over a highly stable bimetallic Nb-Cu/Zr-doped porous silica catalyst
Green Chemistry ( IF 9.3 ) Pub Date : 2019/12/17 , DOI: 10.1039/c9gc03516h
Neha Karanwal _{1,

2,

3,

4} , Deepak Verma _{1,

2,

3,

4,

5} , Paresh Butolia _{2,

3,

4,

6} , Seung Min Kim _{4,

7,

8,

9} , Jaehoon Kim _{1,

2,

3,

4,

5}

Affiliation

The direct conversion of levulinic acid (LA) to valeric biofuel is highly promising for the development of biorefineries. Herein, LA is converted into valeric acid (VA) via one-pot direct cascade conversion over non-noble metal-based Nb-doped Cu on Zr-doped porous silica (Nb-Cu/ZPS). Under mild reaction conditions (150 °C and 3.0 MPa H₂ for 4 h), LA was completely converted into VA in high yield (99.8%) in aqueous medium with a high turnover frequency of 0.038 h⁻¹. The Lewis acid sites of ZPS enhanced the adsorption of LA on the catalyst surface, and both the Lewis and Brønsted acidity associated with Nb₂O₅ and the metallic Cu⁰ sites promoted catalysis of the cascade hydrogenation, ring cyclization, ring-opening, and hydrogenation reactions to produce VA from LA. The bimetallic Nb-Cu/ZPS catalyst was also effective for the conversion of VA into various valeric esters in C1–C5 alcohol media. The presence of Nb₂O₅ effectively suppressed metal leaching and coke formation, which are serious issues in the liquid-phase conversion of highly acidic LA during the reaction. The catalyst could be used for up to five consecutive cycles with marginal loss of activity, even without catalyst re-activation.

中文翻译：

在高度稳定的Nb-Cu / Zr掺杂双金属多孔二氧化硅催化剂上一锅直接将乙酰丙酸转化为高产戊酸

乙酰丙酸（LA）直接转化为戊酸生物燃料对于生物精炼厂的发展是非常有前途的。在此，通过在掺杂Zr的多孔二氧化硅（Nb-Cu / ZPS）上的基于非贵金属的基于Nb的Cu上的一锅直接级联转化，将LA转化为戊酸（VA ）。在温和的反应条件下（150°C和3.0 MPa H ₂持续4 h），LA在水性介质中以高转化率0.038 h ^-1的高收率（99.8％）完全转化为VA 。ZPS的Lewis酸位增强了LA在催化剂表面的吸附，并且Lewis和Brønsted酸度均与Nb ₂ O ₅和金属Cu ^0有关这些位点促进了级联氢化，环环化，开环和氢化反应的催化作用，从而从LA生成VA。N1-Cu / ZPS双金属催化剂在C1-C5醇介质中也能有效地将VA转化为各种戊酸酯。Nb ₂ O ₅的存在有效地抑制了金属浸出和焦炭的形成，这在反应过程中高酸性LA的液相转化中是严重的问题。即使没有催化剂再活化，该催化剂也可以连续使用五个循环，而活性几乎没有损失。

更新日期：2020-02-13

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