Aqueous‐phase hydrodeoxygenation (APH) of bioderived feedstocks into useful chemical building blocks is one the most important processes for biomass conversion. However, several technological challenges, such as elevated reaction temperature (220–280 °C), high H2 pressure (4–10 MPa), uncontrollable side reactions, and intensive capital investment, have resulted in a bottleneck for the further development of existing APH processes. Catalytic transfer hydrogenation (CTH) under much milder conditions with non‐fossil‐based H2 has attracted extensive interest as a result of several advantageous features, including high atom efficiency (≈100 %), low energy intensity, and green H2 obtained from renewable sources. Typically, CTH can be categorized as internal H2 transfer (sacrificing small amounts of feedstocks for H2 generation) and external H2 transfer from H2 donors (e.g., alcohols, formic acid). Although the last decade has witnessed a few successful applications of conventional APH technologies, CTH is still relatively new for biomass conversion. Very limited attempts have been made in both academia and industry. Understanding the fundamentals for precise control of catalyst structures is key for tunable dual functionality to combine simultaneous H2 generation and hydrogenation. Therefore, this Review focuses on the rational design of dual‐functionalized catalysts for synchronous H2 generation and hydrogenation of bio‐feedstocks into value‐added chemicals through CTH technologies. Most recent studies, published from 2015 to 2018, on the transformation of selected model compounds, including glycerol, xylitol, sorbitol, levulinic acid, hydroxymethylfurfural, furfural, cresol, phenol, and guaiacol, are critically reviewed herein. The relationship between the nanostructures of heterogeneous catalysts and the catalytic activity and selectivity for C−O, C−H, C−C, and O−H bond cleavage are discussed to provide insights into future designs for the atom‐economical conversion of biomass into fuels and chemicals.

Selective oxidation of glycerol is one of the most promising routes to produce value-added fine chemicals from biomass. However, achieving good selectivity towards glyceric and lactic acids still remains a grand challenge in this field. A series of unique electronically coupled PtCo catalysts, supported on layered double hydroxides via co-precipitation method, was reported in this work, as they display tunable selectivity toward glyceric acid and lactic acid during glycerol conversion. It is found that the unusual electronic transfer from MgAl hydrotalcite support to cobalt species, leading to high electron binding energy of PtCo sites on catalyst surface. The presence of cobalt components contributes to synergistic enhancement of oxidation activity at electron deficient Pt sites and more critically, weakened Pt-O strength during glycerol conversion. Such unique electronic reconfiguration, as characterized by XRD and XPS spectroscopy, induces two alternative reaction pathways under different reaction temperatures. While Pt-O bonding strength is significantly weakened by strong Co-O affinity at relatively higher reaction temperature (100 °C), such effect is almost negligible at 50 °C. As a result, lactic acid selectivity of 67% was obtained at 100 °C, while glyceric acid selectivity of 65% was achieved at 50 °C, over the bifunctional PtCo/MgAl hydrotalcite catalysts. The design principles reported in this work offer alternative approaches for manufacturing cost-effective catalytic materials for glycerol conversion to various value-added carboxylic acids and derivatives.

Conversion of biomass to chemicals provides essential products to human society from renewable resources. In this context, achieving atom‐economical and energy‐efficient conversion with high selectivity towards target products remains a key challenge. Recent developments in nanostructured catalysts address this challenge reporting remarkable performances in shape and morphology dependent catalysis by metals on nano scale in energy and environmental applications. In this review, most recent advances in synthesis of heterogeneous nanomaterials, surface characterization and catalytic performances for hydrogenation and oxidation for biorenewables with plausible mechanism have been discussed. The perspectives obtained from this review paper will provide insights into rational design of active, selective and stable catalytic materials for sustainable production of value‐added chemicals from biomass resources.

With increasing interest in developing biodegradable polymers to replace fossil-based products globally, lactic acid (LA) has been paid extensive attention due to the high environment-compatibility of its downstream products. The mainstream efforts have been put in developing energy-efficient conversion technologies through biological and chemical routes to synthesize LA. However, to our best knowledge, there is a lack of sufficient attention in developing effective separation technologies with high atom economics for purifying LA and derivatives. In this review, the most recent advances in purifying LA using precipitation, reactive extraction, emulsion liquid membrane, reactive distillation, molecular distillation, and membrane techniques will be discussed critically with respect to the fundamentals, flow scheme, energy efficiency, and equipment. The outcome of this article is to offer insights into implementing more atomic and energy-efficient technologies for upgrading LA.

Xylitol is commonly known as one of the top platform intermediates for biomass conversion. Catalytic deoxygenation of xylitol provides an atomic and energetic efficient way to produce a variety of renewable chemicals including ethylene glycol, 1,2‐propanediol, lactic acid and 1,4‐anhydroxylitol. Despite a few initial attempts in converting xylitol into those products, improving catalyst selectivity towards C−O and C−C cleavage reactions remains a grand challenge in this area. To our best knowledge, there is lack of comprehensive review to summarize the most recent advances on catalyst design and mechanisms in deoxygenation of xylitol, offering important perspective into future development of xylitol transformation technologies. Therefore, in this mini‐review, we have critically discussed the conversion routes involved in xylitol deoxygenation over solid catalyst materials, the nanostructures of supported metal catalysts for C−H, C−C and C−O bond cleavage reactions, and mechanistic investigation for xylitol conversion. The outcome of this work provides new insights into rational design of effective deoxygenation catalyst materials for upgrading of xylitol and future process development in converting hemicellulosic biomass.

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Therefore, in this review article, we have conducted a comprehensive and critical discussion on how steric hindrance and electronic coupling at metal-acid interfaces affect catalytic activation of internal À OH group in glycerol molecule. Selected highlights on the mechanistic investigation for ex-situ and insitu formed Brønsted acidity over Pt-WO x and IrÀ ReO x catalysts, have been discussed with experimental and computational details. The outcome of this review will provide important insights on controllable manipulation of spatial and electronic structures for selective hydrogenation reactions with broader industrial applications.[a] D.