Direct Conversion Research Articles

Front Cover: Homogeneous Catalyzed Direct Conversion of Furfural to Gamma‐Valerolactone (ChemSusChem 11/2024)

Front Cover: Homogeneous Catalyzed Direct Conversion of Furfural to Gamma‐Valerolactone (ChemSusChem 11/2024)

Copper-Nitroxyl-Catalyzed α-Oxygenation of Cyclic Secondary Amines Including Application to Late-Stage Functionalization.

Cyclic secondary amines are prominent subunits in pharmaceutical compounds. Methods for direct functionalization of N-unprotected/unsubstituted piperidines and related heterocycles have limited precedent despite their potential to impact medicinal chemistry and organic synthesis. Herein, we report a Cu/nitroxyl co-catalyzed method for direct conversion of cyclic secondary amines to the corresponding lactams via aerobic dehydrogenation and oxidative coupling with water. The mild reaction conditions tolerate diverse functional groups, enabling application to molecules that cover broad chemical space. The method is showcased in selective functionalization of building blocks and complex molecules, including late-stage functionalization of bromodomain inhibitors.

Oxidative rearrangement of enaminones to α-keto amides in the presence of KI, TBHP and octanoic acid

A novel method for the direct conversion of enaminones to α-keto amides has been developed. This transformation involves an oxidative rearrangement of enaminones under free radical conditions. In the presence of KI, TBHP and octanoic acid, a series of α-keto amides were obtained in moderate to excellent yields. This reaction demonstrates excellent functional group compatibility, utilizes readily available materials, and is easy to perform. Additionally, when o-hydroxyphenyl enaminone was utilized as the substrate, the reaction yielded 3-iodochromone in a high yield.

Synergy between Fe-Co oxide catalysts supported over HZSM-5 for direct conversion of methane to methanol

The direct conversion of methane to methanol over iron and cobalt oxide based composite catalysts supported over HZSM-5 was carried out in a fixed-bed micro reactor under changing process parameters and catalyst compositions. The prepared catalysts were well characterized by various techniques including N2 adsorption desorption, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), pyridine FTIR, X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and temperature programmed reduction (H2-TPR). The characterization results revealed the presence of various reducible iron and cobalt oxide species depending on the Fe/Co molar ratio and total metal oxide loading. Moreover, the XPS and UV–vis spectroscopic results also confirmed the variation of Fe2+/Fe3+ and Co2+/Co3+ species depending on the Fe-Co molar ratio which had strong influence on the performance of the composite catalysts. It was found that the cobalt species favours the formaldehyde formation whereas the iron species promotes the formic acid formation in their respective pure supported oxide catalysts. However, the synergistic effect of iron and cobalt oxide in equimolar ratio in composite catalysts appeared as effective for achieving highest yield of methanol. The methanol selectivity was also influenced by the alteration of various studied process parameters. The higher reaction temperature favoured the overoxidation of methanol to CO2 whereas the methanol selectivity increased with increasing the methane to oxygen ratio. The lattice to adsorbed oxygen ratio also had strong influence on the activity of composite catalysts and methanol selectivity. The highest methanol yield of 1.87% was achieved at the methane conversion of 42.81 % with the 20Fe1Co1Z catalyst at 873 K reaction temperature with CH4/O2 ratio of 2:1 and WHSV of 1030 ml hr−1 gcat−1.

Waste CO2 capture and utilization for methanol production via a novel membrane contactor reactor process: Techno-economic analysis (TEA), and comparison with other existing and emerging technologies

We introduced recently a CO2 capture and utilization (CCU) technology that produces methanol (MeOH), from waste CO2 employing a novel configuration combining a reverse water gas shift reactor (RWGSR) with a membrane contactor reactor for MeOH synthesis (MeS-MCR). The integrated RWGSR/MeS-MCR process overcomes the challenges direct CO2 conversion into MeOH faces and achieves carbon conversions exceeding 80 %, significantly surpassing the equilibrium conversion of ∼ 20–30 % for the MeS reaction. In this study, a techno-economic analysis (TEA) was conducted on the RWGSR/MeS-MCR process along with four other CO2-to-MeOH CCU processes. Key economic parameters, as well as the energy efficiency, were analyzed with respect to CO2 and renewable hydrogen (H2) costs and plant capacity. The study revealed that the RWGSR/MeS-MCR technology has the highest energy efficiency and the best economic performance among all the technologies investigated. All technologies offer the significant societal benefit of capturing and utilizing waste CO2, but under present CO2 and renewable H2 costs, they cannot currently compete cost-wise with conventional MeOH production methods. However, under a future scenario whereby government incentives lower the CO2 cost and technological advances decrease the price of renewable H2, the proposed RWGSR/MeS-MCR process and another catalytic technology (CAMERE) become price competitive.

A low-molecular-weight, long-wavelength emissive Coumarin: Green synthesis, spectral properties, fluorescence enhancement and solvatochromism application

In this study, a novel low-molecular-weight coumarin fluorescent dye, 3,4-dicyano-7-diethylaminocoumarin, was designed. This dye features a donor-π-bridge-acceptor (D-π-A) conjugated structure, which confers superior fluorescence properties.The dye was synthesized using a simple, efficient, and environmentally friendly two-step process, facilitating the direct conversion of the key intermediate into the final product via simultaneous addition and elimination reactions. A comprehensive structural characterization of the dye was undertaken, and its UV absorption and fluorescence emission properties were extensively analyzed using spectroscopic techniques, with structural explanations of the fluorescence activities provided by the Density Functional Theory (DFT) method.Experimental results revealed that this coumarin dye emits strong fluorescence, characterized by a long wavelength, a large Stokes shift, and high fluorescence intensity. It exhibits excellent fluorescent performance in various solvents. Despite experiencing fluorescence quenching in its solid state, the formation of an inclusion complex with β-cyclodextrin restores strong red fluorescence, presenting new possibilities for biofluorescence imaging. Notably, this coumarin dye also demonstrates a significant solvatochromic effect. This effect enables rapid visual discrimination among multiple sets of structurally and chemically similar organic solvents. Consequently, the dye holds promise as a versatile solvatochromic fluorescent probe for a broad spectrum of applications.

Simultaneously enhanced electrical properties and high-power characteristics of (K,Na)NbO3 lead-free piezoceramics by hot-pressing

Piezoelectric materials enabling direct conversion between electrical and mechanical energies are ubiquitously implemented in high-power apparatuses, where both superior piezoelectricity and high-power performance are demanded. However, it remains a challenge to simultaneously achieve the two goals, which are hindered by their antagonistic relationship. Herein, hot-pressing is employed to address this dilemma, as exemplified in lead-free (K,Na)NbO3 (KNN) piezoceramics. In contrast to the samples prepared using normal sintering (NS–KNN), hot-pressed KNN (HP–KNN) polycrystals show higher density, lager piezoelectricity (d33∼129 pC/N), and more active domain wall movement. In particular, the normalized strain d33* of HP-KNN piezoceramics exhibits high thermal stability (variation of d33*<10 %) in a broad temperature range from ambient temperature up to 150 °C. Moreover, the HP-KNN samples show superior high-power characteristics with a maximum vibration speed of 1.1 m/s, which is almost 78 % larger than that of NS-KNN. This study not only demonstrates that the HP-KNN lead-free piezoceramics hold great potential for high-power implements, but also opens a new avenue for integrating antagonistic properties for the enhancement of the collective performance in functional materials.

Synthesis of 8-Methoxy-1-Tetralone

Several methods have been developed for the synthesis of 8-methoxy-1- tetralone 4. The applications of some named organic reactions can be observed during the synthesis of tetralone 4. Attempts have been made to achieve the direct conversion of 5-methoxy-1-tetralone into the tetralone 4. The method for the ring expansion of tertiary cyclobutanol 30 catalyzed by silver salts has proved useful to obtain the title tetralone 4.

Direct conversion of lignin-rich black liquor to activated carbon for supercapacitor electrodes

The escalating industrialization trend underscores the imperative for sustainable waste management practices. The present investigation explores a sustainable methodology for managing the waste generated from the kraft process by directly converting it into activated carbon (BLAC) through a cost-effective hydrothermal-assisted activation method. The research involved a comparative analysis of BLAC with acid-washed black liquor lignin-derived activated carbon (ABLAC) and commercial lignin-derived activated carbon (SALAC). The analysis revealed that BLAC possesses a well-developed micro and mesoporous structure, yielding a significantly higher surface area of 2277.2 m2/g as compared to ABLAC (1260 m2/g) and SALAC (1558.4 m2/g). The presence of inherent alkali in the black liquor is the main factor influencing the surface area of the BLAC. Furthermore, it demonstrated impressive electrochemical performance, showing a specific capacitance value of 871.4 F/g at 1 A/g current density, positioning it as a formidable electrode material for supercapacitor applications. The proposed direct conversion strategy will eliminate the need for high-temperature pre‑carbonization and additional lignin extraction, reducing chemical usage and presenting a greener approach.

ALACEN: A Holistic Herbaceous Biomass Fractionation Process Attaining a Xylose-Rich Stream for Direct Microbial Conversion to Bioplastics.

Lignocellulose biorefining is a promising technology for the sustainable production of chemicals and biopolymers. Usually, when one component is focused on, the chemical nature and yield of the others are compromised. Thus, one of the bottlenecks in biomass biorefining is harnessing the maximum value from all of the lignocellulosic components. Here, we describe a mild stepwise process in a flow-through setup leading to separate flow-out streams containing cinnamic acid derivatives, glucose, xylose, and lignin as the main components from different herbaceous sources. The proposed process shows that minimal degradation of the individual components and conservation of their natural structure are possible. Under optimized conditions, the following fractions are produced from wheat straw based on their respective contents in the feed by the ALkaline ACid ENzyme process: (i) 78% ferulic acid from a mild ALkali step, (ii) 51% monomeric xylose free of fermentation inhibitors by mild ACidic treatment, (iii) 82% glucose from ENzymatic degradation of cellulose, and (iv) 55% native-like lignin. The benefits of using the flow-through setup are demonstrated. The retention of the lignin aryl ether structure was confirmed by HSQC NMR, and this allowed monomers to form from hydrogenolysis. More importantly, the crude xylose-rich fraction was shown to be suitable for producing polyhydroxybutyrate bioplastics. The direct use of the xylose-rich fraction by means of the thermophilic bacteria Schlegelella thermodepolymerans matched 91% of the PHA produced with commercial pure xylose, achieving 138.6 mgPHA/gxylose. Overall, the ALACEN fractionation method allows for a holistic valorization of the principal components of herbaceous biomasses.

Innovative approaches for amino acid production via consolidated bioprocessing of agricultural biomass.

Agricultural plantations in Indonesia and Malaysia yield substantial waste, necessitating proper disposal to address environmental concerns. Yet, these wastes, rich in starch and lignocellulosic content, offer an opportunity for value-added product development, particularly amino acid production. Traditional methods often rely on costly commercial enzymes to convert biomass into fermentable sugars for amino acid production. An alternative, consolidated bioprocessing, enables the direct conversion of agricultural biomass into amino acids using selected microorganisms. This review provides a comprehensive assessment of the potential of agricultural biomass in Indonesia and Malaysia for amino acid production through consolidated bioprocessing. It explores suitable microorganisms and presents a case study on using Bacillus subtilis ATCC 6051 to produce 9.56mg/mL of amino acids directly from pineapple plant stems. These findings contribute to the advancement of sustainable amino acid production methods using agricultural biomass especially in Indonesia and Malaysia through consolidated bioprocessing, reducing waste and enhancing environmental sustainability.

Laser-induced graphene formation on different wood species: Dependence of electronic performance on intrinsic features of certain types of wood

Conductive, 3D, porous graphene can be produced with a CO2 laser from a large variety of materials, including wood, at room temperature, and under inert atmosphere or after treatment for fire protection. Here, we investigated the suitability for direct conversion of 46 typical European and Asian woods into laser-induced graphene (LIG), without pre-treatment. The LIG was characterized by resistance measurements to determine if a conductive layer had formed, and via Raman spectroscopy. Here, we show, for the first time, that it is possible to produce LIG on certain woods under atmospheric conditions without additional fire protection treatment. We determined that the ability to produce LIG on untreated, natural wood under ambient atmosphere is favoured overall by a high density and a diffuse-porous xylem structure, as well as a high soluble lignin content. Some of these characteristics are similar to those required for high yields in char production. Problematic for the production of LIG-based electronics is the presence of pronounced growth rings, or other geometric wood features, with density variations, which can be reduced using specific cuts with minimized growth rings and absence of rays. This is the first time that untreated wood has been directly converted into LIG using a conventional CO2 laser and ambient atmosphere. Our results represent a further step towards the development of a new generation of sustainable electronics relying on natural materials.

A Density Functional Theory Analysis of Electrochemical Oxidation of Methane to Alcohol over High-Entropy Oxide (CoCrFeMnNi)3O4 Catalysts.

The direct conversion of methane into alcohol is a promising approach for achieving a low-carbon future, yet it remains a major challenge. In this study, we utilize density functional theory to explore the potential of the (CoCrFeMnNi)3O4 (CCFMNO) high entropy oxide (HEO) for electrochemical oxidation of methane to methanol and ethanol, alongside their competition with CO2 production. Our primary focus in this study is on thermodynamics, enabling a prompt analysis of the catalyst's potential, with the calculation of electrochemical barriers falling beyond our scope. Among all potential active sites within CCFMNO HEO, we identify Co as the most active site for methane activation when using carbonate ions as oxidants. This results in methanol production with a limiting potential of 1.4 VCHE, and ethanol and CO2 productions with a limiting potential of 1.2 VCHE. Additionally, our findings suggest that the occupied p-band center of O* on CCFMNO HEO is a potential descriptor for identifying the most active site within CCFMNO HEO. Overall, our results indicate that CCFMNO HEO holds promise as catalysts for methane oxidation to alcohols, employing carbonate ions as oxidants.

SuFEx-Enabled Direct Deoxy-Diversification of Alcohols.

We introduce a new use of sulfonyl fluoride as a bifunctional reagent that facilitates the one-step deoxy-diversification of complex alcohol libraries. Our reaction design features a Sulfur(VI) Fluoride Exchange (SuFEx) mediated activation of alcohols and fluoride-induced activation of silicon-bound nucleophiles. This method enables the direct conversion of alcoholic C-O bonds in complex molecules into diverse analogues via C-C, C-N, C-Cl, and C-Br bond formation while suppressing any elimination side-products.

Silver Copper Chalcogenide Thermoelectrics: Advance, Controversy, and Perspective.

Thermoelectric technology, which enables a direct and pollution-free conversion of heat into electricity, provides a promising path to address the current global energy crisis. Among the broad range of thermoelectric materials, silver copper chalcogenides (AgCuQ, Q = S, Se, Te) have garnered significant attention in thermoelectric community in light of inherently ultralow lattice thermal conductivity, controllable electronic transport properties, excellent thermoelectric performance across various temperature ranges, and a degree of ductility. This review epitomizes the recent progress in AgCuQ-based thermoelectric materials, from the optimization of thermoelectric performance to the rational design of devices, encompassing the fundamental understanding of crystal structures, electronic band structures, mechanical properties, and quasi-liquid behaviors. The correlation between chemical composition, mechanical properties, and thermoelectric performance in this material system is also highlighted. Finally, several key issues and prospects are proposed for further optimizing AgCuQ-based thermoelectric materials.

Design and synthesis of SO3H-based ionic liquids for direct catalytic conversion of straw to levulinic acid

The utilization of ionic liquids (ILs) in the conversion of lignocellulose to levulinic acid (LA) is a significant pathway in the field of bio-refinery. In this study, a series of sulfonic-based ILs with elongated alkyl chains were synthesized using density functional theory. These ILs were then utilized for the conversion of straw into LA in a single reaction vessel. The yield of LA was compared between a single solvent (water) and a biphasic system comprising water and methyl isobutyl ketone (MIBK). Among the investigated ILs, [C3SO3HEim]Cl exhibited a higher yield of LA, reaching up to 11.3 wt% in the aqueous phase and 17.8 wt% in the MIBK-water biphasic system. Furthermore, [C3SO3HEim]Cl displayed a high catalytic efficiency (90.4%) and a yield of LA (16.3 wt%) after 5 cycles. These findings suggest that the elongation of alkyl side chains in ILs enhances the solubility of cellulose and increases the yield of LA. The MIBK-water biphasic system promotes the rehydration of hydroxymethylfurfural (HMF) and reduces the residence time of LA in the aqueous phase, thereby optimizing its yield. This innovative approach involving ILs and the MIBK-water biphasic system presents a novel perspective for the production of LA from biomass.

英语被动句的汉译探析

In the academic research and practice of English translation, in-depth analysis and discussion on English passive sentences and their Chinese translation strategies are of great significance. This article employs a variety of Chinese translation strategies including direct conversion, active sentence conversion, addition, omission, and segmentation to unveil and analyze the essential factors that must be considered in the process of translating English passive sentences into Chinese. These factors encompass word class, grammatical structure, and specific language habits, underscoring their importance in ensuring the accuracy and fluency of translations. This paper aims to assist scholars and learners in the field of English translation not only to gain a deeper understanding of the grammatical and semantic characteristics of English passive sentences but also to master and apply effective translation techniques to enhance their ability to accurately translate English passive sentences into Chinese.

Bioelectrochemical anaerobic digestion mitigates microplastic pollution and promotes methane recovery of wastewater treatment in biofilm system

Bioelectrochemical systems (BES) offer significant potential for treating refractory waste and recovering bioenergy. However, their ability to mitigate microplastic pollution in wastewater remains unexplored. This study showed that BES facilitated the treatment of polyethylene (PE), polyvinyl chloride (PVC), and Mix (PE+PVC) microplastic wastewater and the methane recovery (40.61%, 20.02%, 21.19%, respectively). The lactate dehydrogenase (LDH), adenosine triphosphate (ATP), cytochrome c, and nicotinamide adenine dinucleotide (NADH/NAD+) ratios were elevated with electrical stimulation. Moreover, the applied voltage improved the polysaccharides content of the extracellular polymeric substances (EPS) in the PE-BES but decreased in PVC-BES, while the proteins showed the opposite trend. Metatranscriptomic sequencing showed that the abundance of fermentation bacteria, acetogens, electrogens, and methanogens was greatly enhanced by applying voltage, especially at the anode. Methane metabolism was dominated by the acetoclastic methanogenic pathway, with the applied voltage promoting the enrichment of Methanothrix, resulting in the direct conversion of acetate to acetyl-CoA via acetate-CoA ligase (EC: 6.2.1.1), and increased metabolic activity in the anode. Moreover, applied voltage greatly boosted the function genes expression level related to energy metabolism, tricarboxylic acid (TCA) cycle, electron transport, and transporters on the anode biofilm. Overall, these results demonstrate that BES can mitigate microplastic pollution during wastewater treatment.

Synthesis and characterization of absorption-enhanced alumina solid particle materials for direct irradiation solar-thermal conversion

Based on solar-thermal application more than 1000 °C, a novel combination of sol-gel synthesis and stepwise calcination to prepare metal-ion doped alumina composite particles as heat transfer media were proposed, enhancing solar energy absorption and lowering preparation temperature. Investigations focused on the elemental distribution, phase composition, oxidation states, optical properties and thermal stability of the composites, which were doped with Cr, Co, Cu, Fe, and Mn metal ions in a 100:5 M ratio. The first-principles calculations elucidate the mechanism behind the impact of transition metal ions on alumina’s optical properties. Results show that introducing a small quantity of metal atoms results in new impurity energy levels and electron states around EF = 0. Specifically, the band gap energy of Cu- and Mn–Al2O3 decreases from 6.017 eV to 4.464 eV and 2.170 eV, respectively. Correspondingly, the absorptivity of these composite particles increases from around 20 %–76.6 %. And Tauc analysis indicates a decrease in the optical band gap of the particle materials from 5.37 eV to a range of 2.88–4.90 eV. Additionally, doping with Mn, Fe, and Cu accelerates the in-situ formation of α-Al2O3 crystals, with a phase transition temperature below 1000 °C and a crystallinity exceeding 93 %. Thermal stability tests show that the particles are highly stable, exhibiting a mere 0.49 % mass change between 30 °C and 1200 °C. The stepwise inert annealing strategy and metal-iron doping positively influence the optical performance of alumina, synthesizing long-term high-temperature stable alumina ceramic particles with absorptance enhancement and a low α-Al2O3 phase transition temperature. These attributes make a favorable choice for solar-thermal applications in direct irradiation.

Effect of Na+ migration and the component proximity on direct conversion of aromatics into aromatics over Fe-based zeolite bifunctional catalysts

Direct conversion of syngas into aromatics (STA) via Fischer-Tropsch (F-T) synthesis, using Fe-based zeolite bifunctional catalysts, has recently become a topic of great interest. The catalytic performance of the Fe-based zeolite bifunctional catalyst is influenced by the component proximity in the STA reaction, in addition to their physicochemical properties. However, the mechanism by which the component proximity affects the STA performance is still unclear. Herein, we investigate the effect of Na+ migration and the component proximity on the F-T reactivity, the aromatic distribution, and catalyst stability in a Fe-based ZSM-5 catalyst system. The correlation between the proximity of two components, the migration of alkali-metal promoters, the evolution of the Fe-based active phase, and the coke on the zeolite is analyzed using XRD, XPS, FT-IR, TG, Mössbauer spectroscopy techniques. The findings indicate that when the components are closer to each other, it encourages the formation of iron carbides and inhibits the coke deposition on the zeolite. However, the migration of alkali metals and the acidic environment of zeolite can decrease the catalyst’s stability and F-T reactivity. Moreover, by improving the hydrophobic nature of the zeolite, we can prevent the transfer of alkali-metal promoters from the Fe-based component to zeolite. This enhances the stability of Fe-based ZSM-5 catalysts in the STA reaction, suggesting a new approach to improve their STA performance.