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To make pyrolytic bio‐oil useful as a transportation fuel, the oxygen content must be reduced, and this can be carried out by using catalytic hydrodeoxygenation (HDO) reaction. The greatest challenge is associated with the removal of strongly bound oxygenated groups without saturating the aromatic ring while preserving the number of carbons. However, the development of a stable catalyst that can selectively remove such oxygenated groups with low hydrogen consumption is still challenging. In this context, a systematic study on HDO of vanillin on bimetallic Pd−Pt catalysts was carried out. It aims to study the effect of bimetallic synergy in terms of activity and selectivity to creosol. Metallic nanoparticles of Pd and Pt were synthesized by sol immobilization technique and deposited on TiO2. The conversion of vanillin was correlated to the Pd−Pt atomic ratio, while the production of the creosol was correlated to the Pd(0)/(Pd+Pt) ratio at the surface. Full conversion of vanillin was obtained at low reaction temperature (20 °C) achieving nearly 100 % selectivity to creosol. These results represent a step forward in advancing the development of more efficient and sustainable processes for bio‐oil upgrading. [ABSTRACT FROM AUTHOR]

In this work, solid-state fermentation (SSF) was applied to babassu mesocarp (BM) for the low-cost bioproduction of natural aroma compounds having Trichoderma harzianum (IOC 4042) and Geotrichum candidum (CCT 1205) as microbial agents. Fermentation was carried out using in natura babassu mesocarp (IN-BM) and defatted babassu mesocarp through soxhlet extraction (DEF-BM) as support, impregnated with hydration solutions of three and seven salts. The compounds produced were analyzed using solid phase microextraction (SPME) and gas chromatography coupled with a mass spectrometer (GC-MS). Among several aroma compounds detected, 6-pentyl-α-pyrone (6-PP)—GRAS 3696, coconut aroma; 2-phenylethanol (2-PE)—GRAS 2858, rose and honey aroma; and hexanal—GRAS 2557, green apple aroma, were the compounds that that were detected with the greatest intensity. The highest concentrations (ppm (w/w)) of 6-PP and 2-PE were obtained in DEF-BM using NS7SG (308.17 ± 3.18 and 414.53 ± 1.96), respectively, while for hexanal, the highest concentration (ppm (w/w)) was obtained in IN-BM using NS7SG (210.83 ± 2.14). The results indicate that producing aroma compounds by G. candidum and T. harzianum through BM SSF is viable, generating value-added compounds. [ABSTRACT FROM AUTHOR]

Strong metal–support interaction (SMSI) is a pivotal strategy in thermal catalysis; however, its application in photocatalysis leaves ample area for further development. A method inducing SMSI between earth-abundant metals, such as copper and TiO2, at room temperature, and thus hindering the agglomeration of copper species remains rarely reported. In this work, we achieved SMSI construction of TiO2 overlayers on Cu nanoparticles via a straightforward soft-chemistry method. SMSI coverage is stable even after high-temperature treatment in the air (500 °C), as demonstrated by chemical mapping and surface analysis. The method is more accurate than thermal reduction since it produces a metastable, highly active anatase phase. Interestingly, the TiO2 overlayer induces the formation of four-coordinated copper(II) species surrounded by oxygen atoms, resulting in coexisting CuO2 planes, which were monitored through high-resolution transmission electron microscopy and electron paramagnetic resonance spectroscopy. The stronger interfacial interaction by forming Ti–O–Cu bonding promotes charge carrier separation, producing twice as much H2 than the low interfacial interaction within a conventional photoactive system wherein copper was decorated onto TiO2. Our approach offers a rational design for SMSI materials in photocatalysis, which is extendable to other catalytic reactions. [ABSTRACT FROM AUTHOR]

This study investigated the oxidation of 5-hydroxymethylfurfural (HMF) to produce valuable products such as 2,5-furandicarboxaldehyde (DFF), 5-formyl-2-furancarboxylic acid (FFCA) and 2,5-furandicarboxylic acid (FDCA) through (photo) chemical and enzymatic catalysis. Laccases from different sources, including Aspergillus spp., Pseudomonas cepacea, and Trametes versicolor, were evaluated for their catalytic activity in the HMF oxidation. Laccase from Trametes versicolor (LacTV) emerged as the most effective catalyst, achieving complete conversion of HMF under specific pH conditions. The reaction mechanisms were explored, revealing a preference for the primary alcohol oxidation pathway over the aldehyde, leading to the formation of DFF and subsequent conversion to FFCA and FDCA. The impact of substrate concentration on HMF conversion was examined, revealing optimal conversion at lower HMF concentrations (<100 mM) and reduced performance at higher concentrations (>100 mM). The study also examined the influence of blue light (430 nm) on this reaction, revealing the dependence on light exposure for gC3N4 based catalysts and a negative effect for LacTV. Furthermore, the study introduces a modular flow chemical platform that utilizes Continuous Stirred Tank Reactors (CSTR) in a cascade configuration, the optimization of HMF oxidation. The implementation of this innovative approach has led to the effective synthesis of FDCA, demonstrating an impressive 40-fold increase in productivity compared to the traditional batch system. These results present significant potential for advancing green chemistry and sustainable chemical synthesis, introducing novel possibilities for environmentally friendly HMF oxidation processes. [ABSTRACT FROM AUTHOR]

In the quest to combat global warming, traditional thermal chemistry processes are giving way to selective photocatalysis, an eco-friendly approach that operates under milder conditions, using benign solvents like water. Benzaldehyde, a versatile compound with applications spanning agroindustry, pharmaceuticals, and cosmetics, serves as a fundamental building block for various fine chemicals. This study aims at enhancing benzaldehyde production sustainability by utilizing photooxidation of benzyl alcohol. Gold nanoparticle-based catalysts are renowned for their exceptional efficiency in oxidizing bio-based molecules. In this research, Au nanoparticles were anchored onto three distinct supports:  T i O 2 ,  Z r O 2 , and graphitic carbon nitride (g- C 3 N 4 ). The objective was to investigate the influence of the support material on the selective photocatalysis of benzyl alcohol. In the preparation of g- C 3 N 4 , three different precursors—melamine, urea, and a 50:50 mixture of both—were chosen to analyze their impact on catalyst performance. After 4 h of irradiation at 365 nm, operating under acidic conditions (pH = 2), the Au photocatalyst on graphitic carbon nitride support synthesized using urea precursor (Au@g- C 3 N 4 (u r e a) ) displayed the optimal balance between conversion (75%) and selectivity (85%). This formulation outperformed the benchmark Au@TiO2, which achieved a similar conversion rate (80%) but exhibited lower selectivity (55%). [ABSTRACT FROM AUTHOR]

The hydrodeoxygenation of furfural (FF) over Mo carbides in liquid phase at 200 °C, 30 bar of H2 for 4 h in 2‐butanol was investigated. Unsupported and SiO2‐supported Mo carbide with different crystallographic phases (β‐Mo2C/SiO2 and α‐MoC/SiO2), and in the presence of Cu and Ni as promoters were studied. The reactivation treatment under H2 atmosphere of the passivated Mo carbides was investigated by XAS. The results show that Mo is present in different states of oxidation in the passivated catalysts, with more severe oxidation in the bimetallic systems, in which the original carbides are not restored after reactivation. Finally, the product distribution in the HDO of furfural is modified as a function of catalyst oxidation degree. Using the less oxidized Mo carbide (β‐Mo2C), a higher yield to 2‐methylfuran is obtained, while C10 condensation products are formed for the more oxidized catalysts. [ABSTRACT FROM AUTHOR]

In recent years, the synthesis of bio‐based polymers and compounds has grown due to greater environmental concerns and the need to develop green and sustainable products as substitutes for fossil derivatives. In this context, lignocellulosic biomass is an important source of raw materials, as it is abundant and low‐cost, in addition to its chemical variety. Thus, chemical catalysis and biocatalysis have been important tools for obtaining these high value‐added compounds. With the aim of detecting the current scenario, as well as the main challenges and opportunities in the production of bio‐based polymers through the valorization of biomass, this work carried out a technological investigation of articles published in the last 10 years, establishing a relationship between the conditions of each production route and its main challenges. The results show a growing number of publications in the last 6 years involving the application of biomass‐derived molecules as monomers to obtain various classes of polymers, where polyesters and polyurethanes have been the most studied. The use of heterogeneous chemical catalysts is still the predominant production strategy, due to the extreme conditions required for production. However, the application of enzymes such as lipases to obtain polyesters and microbial biotransformation to obtain polyhydroxyalkanoates have been emerging as promising strategies within the context of biorefineries. Almost all works are at the proof‐of‐concept stage, where most of the molecules produced have been obtained from synthetic starting materials, demonstrating the need to integrate technologies for obtaining monomers directly from biomass and synthesis protocols for the advent of new processes that are more sustainable and competitive with traditional routes. [ABSTRACT FROM AUTHOR]

Exploring the potential of utilizing CO2 for commercial purposes is a promising opportunity, especially in light of the growing research efforts towards CO2 capture, storage, and utilization as well as green H2 production. This review article delves into catalyst features and other technological aspects of a plausible process for the indirect conversion of CO2 into glycolic acid, which involves the following steps: CO2 capture, water electrolysis, CO2 hydrogenation to methanol, catalytic oxidation to formaldehyde, and formaldehyde carbonylation to glycolic acid. We adopt an industrial perspective to address this challenge effectively, thoroughly evaluating different processing alternatives with emphasis on the catalytic systems to optimize glycolic acid production performance. [ABSTRACT FROM AUTHOR]

Engineering the composition and geometry of metallic sites has become a popular manner to boost reaction rate and control reaction selectivity in heterogeneous catalysis. Many studies have been devoted to enhancing the stability of metallic nanoparticles during catalytic reactions by dispersion on metal oxide supports such as TiO2, CeO2 or Nb2O5. These supports not only modulate electronic properties and dispersion/stabilization of metallic nanoparticle but also influence catalytic selectivity, resulting in the so‐called "strong metal‐support interaction" (SMSI). In this minireview, we outlined the discovery and fundamentals of SMSI, as well as its extensive development over years. In addition, we summarized recent approaches developed to induce the construction of SMSI between different metal nanoparticles and metal oxide supports. Associated characterization microscopic and spectroscopic techniques were emphasized. Despite being a prevalent concept in catalysis, the number of studies on SMSI in heterogeneous photocatalysis has been even in limitation. Herein, we highlighted the beneficial effects of SMSI on boosting photocatalytic activity for CO2 reduction and H2 evolution reactions. In general, despite some controversial aspects of the SMSI, this concept offers wide opportunities ahead and encourages researchers to rethink the local active site localization and photocatalyst design. [ABSTRACT FROM AUTHOR]

Supported gold nanoparticles have proven to be highly effective catalysts for the base-free oxidation of furfural, a compound derived from biomass. Their small size enables a high surface-area-to-volume ratio, providing abundant active sites for the reaction to take place. These gold nanoparticles serve as catalysts by providing surfaces for furfural molecules to adsorb onto and facilitating electron transfer between the substrate and the oxidizing agent. The role of the support in this reaction has been widely studied, and gold–support interactions have been found to be beneficial. However, the exact mechanism of furfural oxidation under base-free conditions remains an active area of research and is not yet fully understood. In this review, we delve into the essential factors that influence the selectivity of furfural oxidation. We present an optimization process that highlights the significant role of machine learning in identifying the best catalyst for this reaction. The principal objective of this study is to provide a comprehensive review of research conducted over the past five years concerning the catalytic oxidation of furfural under base-free conditions. By conducting tree decision making on experimental data from recent articles, a total of 93 gold-based catalysts are compared. The relative variable importance chart analysis reveals that the support preparation method and the pH of the solution are the most crucial factors determining the yield of furoic acid in this oxidation process. [ABSTRACT FROM AUTHOR]

Bio‐oil obtained from the depolymerization of lignocellulosic biomass is a potential alternative source to replace fossil fuels. However, due to high oxygen content, the bio‐oil must be upgraded. In this direction, the hydrodeoxygenation reaction (HDO) is widely applied. Considering the complex chemical composition of the bio‐oil, a variety of model molecules have been used in the literature to study the mechanism of the HDO process. In this work, we discuss heterogeneous catalysts and reaction conditions (temperature, pressure, and solvent) generally used for the HDO of dimeric aryl ethers representative of the main ether linkages present in the lignin:α‐O‐4, β‐O‐4, and 4‐O‐5. The present work aims to shed light on the role of metal and acid sites and understand the influence of the reaction conditions on the reaction pathways. [ABSTRACT FROM AUTHOR]

The effect of metal and support acidity on the hydroconversion of dimeric aryl ethers, used as model molecules for lignin, is still under debate, both in terms of hydrogenolysis (cleavage of the ether bond) and formation of by-products (coupling of aromatic monomers to dimers by alkylation reaction). Their role is investigated here in the conversion of three typical molecules representative of the α-O-4, β-O-4, and 4-O-5 ether linkages of lignin, respectively, benzyl phenyl ether (BPE), phenethoxybenzene (PEB), and diphenyl ether (DPE), at 503 K, under 18 bar of H2 in decalin. Ru- and Pd-based catalysts were synthesized on non-acidic SiO2 and on acidic HZSM5. Under these reaction conditions, the conversion of the ethers over the bare supports was observed in the presence of acidic sites; the effect decreased as the ether bond strength increased. The results also suggest that the product distribution is directly affected both by the support acidity and by the oxophilicity of Ru. Alkylated products from isomerization reactions, which are reported to be formed only over acidic sites, were also produced on the surface of the Ru nanoparticles. [ABSTRACT FROM AUTHOR]

The conversion of biomass as a sustainable path to access valuable chemicals and fuels is very attractive for the chemical industry, but catalytic conversions still often rely on the use of noble metals. Sustainability constraints require developing alternative catalysts from abundant and low-cost metals. In this context, NiFe nanoparticles are interesting candidates. In their reduced and supported form, they have been reported to be more active and selective than monometallic Ni in the hydrogenation of the polar functions of organic molecules, and the two metals are very abundant. However, unlike noble metals, Ni and Fe are easily oxidized in ambient conditions, and understanding their transformation in both oxidative and reductive atmospheres is an important though seldom investigated issue to be addressed before their application in catalysis. Three types of NiFe nanoparticles were prepared by an organometallic approach to ensure the formation of ultrasmall nanoparticles (<3.5 nm) with a narrow size distribution, controlled composition and chemical order, while working in mild conditions: Ni2Fe1 and Ni1Fe1, both with a Ni rich core and Fe rich surface, and an alloy with a Ni1Fe9 composition. Supported systems were obtained by the impregnation of silica with a colloidal solution of the preformed nanoparticles. Using advanced characterization techniques, such as wide-angle X-ray scattering (WAXS) and X-ray absorption spectroscopy (XAS) in in situ conditions, this study reports on the evolution of the chemical order and of the oxidation state of the metals upon exposure to air, hydrogen, and/or increasing temperature, all factors that may affect their degree of reduction and subsequent performance in catalysis. We show that if oxidation readily occurs upon exposure to air, the metals can revert to their initial state upon heating in the presence of H2 but with a change in structure and chemical ordering. [ABSTRACT FROM AUTHOR]