Furans represent one of the most important classes of intermediates in the conversion of non-edible lignocellulosic biomass into bio-based chemicals and fuels. At present, bio-furan derivatives are generally obtained from cellulose and hemicellulose fractions of biomass via the acid-catalyzed dehydration of their relative C6–C5 sugars and then converted into a wide range of products. Furfural (FUR) and 5-hydroxymethylfurfural (HMF) are surely the most used furan-based feedstocks since their chemical structure allows the preparation of various high-value-added chemicals. Among several well-established catalytic approaches, hydrogenation and oxygenation processes have been efficiently adopted for upgrading furans; however, harsh reaction conditions are generally required. In this review, we aim to discuss the conversion of biomass derived FUR and HMF through unconventional (transfer hydrogenation, photocatalytic and electrocatalytic) catalytic processes promoted by heterogeneous catalytic systems. The reaction conditions adopted, the chemical nature and the physico-chemical properties of the most employed heterogeneous systems in enhancing the catalytic activity and in driving the selectivity to desired products are presented and compared. At the same time, the latest results in the production of FUR and HMF through novel environmental friendly processes starting from lignocellulose as well as from wastes and by-products obtained in the processing of biomass are also overviewed.

中文翻译：

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用于制备和提纯生物质衍生的糠醛和5-羟甲基糠醛的最新催化路线。

呋喃是非食用木质纤维素生物质转化为生物基化学品和燃料中最重要的中间体类别之一。目前，生物呋喃衍生物通常通过生物质的纤维素和半纤维素级分通过酸催化其相对的C6-C5糖脱水，然后转化为多种产品。糠醛（FUR）和5-羟甲基糠醛（HMF）无疑是最常用的呋喃基原料，因为它们的化学结构允许制备各种高附加值的化学品。在几种公认的催化方法中，氢化和氧化过程已被有效地用于提纯呋喃。但是，通常需要苛刻的反应条件。在这篇综述中，我们旨在讨论由非均相催化体系促进的非常规（转移氢化，光催化和电催化）催化过程对生物质衍生的FUR和HMF的转化。采用的反应条件 介绍并比较了最常用的异质体系在增强催化活性和驱动对所需产物的选择性中的化学性质和物理化学性质。同时，还概述了通过新颖的环保工艺从木质纤维素以及生物质加工中获得的废物和副产品生产FUR和HMF的最新结果。