High Conversion Yield Research Articles

Scalable Electro-Biosynthesis of Ectoine from Greenhouse Gases.

Converting greenhouse gases into valuable products has become a promising approach for achieving a carbon-neutral economy and sustainable development. However, the conversion efficiency depends on the energy yield of the substrate. In this study, we developed an electro-biocatalytic system by integrating electrochemical and microbial processes to upcycle CO2 into a valuable product (ectoine) using renewable energy. This system initiates the electrocatalytic reduction of CO2 to methane, an energy-dense molecule, which then serves as an electrofuel to energize the growth of an engineered methanotrophic cell factory for ectoine biosynthesis. The scalability of this system was demonstrated using an array of ten 25 cm2 electrochemical cells equipped with a high-performance carbon-supported isolated copper catalyst. The system consistently generated methane at the cathode under a total partial current of approximately -37 A (~175 mmolCH4 h-1) and O2 at the anode under a total partial current of approximately 62 A (~583 mmolO2 h-1). This output met the requirements of a 3-L bioreactor, even at maximum CH4 and O2 consumption, resulting in the high-yield conversion of CO2 to ectoine (1146.9 mg L-1). This work underscores the potential of electrifying the biosynthesis of valuable products from CO2, providing a sustainable avenue for biomanufacturing and energy storage.

Saccharomyces cerevisiae whole cell biotransformation for the production of aldehyde flavors and fragrances

9-Carbon aldehydes such as (2E)-nonenal, (3Z)-nonenal, and (2E,6Z)-nonadienal are important melon and cucumber fragrance compounds. Currently, these molecules are produced either synthetically, which faces consumer aversion, or through biotransformation using plant-extracted enzymes, which is costly and inefficient. In this study, we constructed a Saccharomyces cerevisiae platform for the whole cell biotransformation of polyunsaturated fatty acids (PUFAs) to 9-carbon aldehydes. Heterologous expression of lipoxygenase (LOX) from Nicotiana benthamiana and hydroperoxide lyase (HPL) from Cucumis melo (melon) in S. cerevisiae enabled the production of (2E)-nonenal from readily available polyunsaturated fatty acid substrates. A 5.5-fold increase in (2E)-nonenal titer was then achieved utilizing genetic and reaction condition enhancement strategies. The highest titer of (2E)-nonenal was more than 0.11 mM, with about 9% yield. This platform can potentially be used to produce a variety of other aldehyde products by customizing with LOX and HPL enzymes of different regio-selectivities.Key points• Establishment of a S. cerevisiae whole-cell biotransformation platform for cost-efficient, high-yield conversion of PUFAs into high value 9-carbon aldehyde compounds• 5.5-Fold improvement of (2E)-nonenal titer to > 0.11 mM achieved by enhancing reaction conditions and gene expression levels of LOX and HPL

Membrane Separations in Biomass Processing.

The development of integrated biorefineries and the greater utilization of biomass resources to reduce dependence on fossil fuel-derived products require research emphasis not just on conversion strategies but also on improving separations associated with biorefining. A significant roadblock towards developing biorefineries is the lack of effective separation techniques evidenced by the lack of literature in this area. Additionally, high conversion yields may only be realized if effective separations generate feedstock of sufficient purity - this makes research into biomass conversion strategies all the more critical. In this review, the challenges associated with biomass separations are discussed, followed by an overview of the most appropriate separation strategies for processing biomass. One of the unit operations most appealing for biorefining, membrane separations (MS), is then considered along with a review of the recent literature utilizing this technique in biomass processing.

Nickel ferrite decorated noble metal containing nitrogen-doped carbon nanotubes as potential magnetic separable catalyst for dinitrotoluene hydrogenation

The 2,4-toluenediamine (TDA) is one of the most important chemicals in the polyurethane industry, produced by the catalytic hydrogenation of 2,4-dinitrotoluene (DNT). The development of novel catalysts that can be easily recovered from the reaction mixture is of paramount importance. In our work, a NiFe2O4/N-BCNT supported magnetic catalyst was prepared by a modified coprecipitation method. The catalyst support alone also showed activity in the synthesis of TDA. Platinum nanoparticles were deposited on the catalyst support surface by a fast, relatively simple, and efficient sonochemical method, resulting in a readily applicable catalytically active system. The prepared catalyst exhibited high activity in hydrogenation tests, which was proved by the exceptionally high DNT conversion (100% for 120 min at 333 K) and TDA yield (99%). Furthermore, the magnetic catalyst can be easily recovered from the reaction medium by the action of an external magnetic field, which can greatly reduce catalyst loss during separation.

Synthesis of Ceiba pentandra biodiesel using ultrasound and infrared radiation: Comparison and fuel characterisation.

Abstract The continuous expending of the economy and population in modern society has caused an increase in energy usage. Currently, fossil fuels and renewable energy are used to generate energy, contributing to greenhouse gas emissions. A significant effort has been made globally to address the issue of rising emissions by boosting the usage of renewable energy. In comparison to fossil fuels, biodiesel has many benefits, including the ability to be produced from a wide range of feedstocks, the ability to be renewable, and the reduction of atmospheric pollution emissions. Besides, advanced technologies can help the biodiesel sector meet the energy demand while producing high-quality biodiesel. The Ceiba pentandra was used for biodiesel production using ultrasound-infrared applications in the present research work. The study aims to produce biodiesel for a better conversion rate and improve fuel properties. Comparisons were conducted using a combination of infrared ultrasound versus ultrasound irradiation. The results show that ultrasound produced the highest yield of 98.76% when the conditions were as follows: methanol/oil ratio: 60%, KOH: 1%, reaction time: 50 minutes. Yet, the addition of infrared on ultrasound has also produced a high conversion yield in a shorter time than ultrasound. A 98.42% biodiesel yield option when using infrared-ultrasound irradiation with conditions as follows: methanol/oil ratio: 60%, KOH: 1%, reaction time: 30 minutes. As both applications were examined, the ultrasound-infrared application was preferable in saving time and energy constraints for biodiesel production. The fuel properties were found to be equivalent to ASTM D6751 and EN 14214 biodiesel standards.

Reaction engineering for high yield electrosynthesis: Unraveling the impact of reaction conditions and conversion on methanol oxidation to formate

Electrochemical processes offer defossilized alternatives to conventional routes. Key processes, such as hydrogen evolution and electrochemical CO2 reduction, are typically paired with the anodic oxygen evolution reaction (OER). However, the generated oxygen holds little value and the electrical costs associated with energy-intensive OER pose a significant economic barrier. The methanol oxidation reaction (MOR) to formate is a promising alternative to OER, requiring less energy and providing a value-added product. Extensive research focuses on MOR regarding high Faraday efficiencies, but conversion and product yields are mostly neglected. However, high conversion with sufficient yield is a prerequisite to transition from lab-scale catalysis towards feasible industrial applications. In this work, we investigated the selectivity of MOR to formate with progressing conversion at high current densities of up to 200mA/cm2 on hierarchically structured copper(II) oxide electrodes. We assessed the impact of the reaction conditions, including current density, temperature, flow rate, electrolyte composition, and membrane type. We found a positive influence of low current density and high temperature on the FE. Through tailored reaction conditions, we achieved a formate yield of 70% at 100mA/cm2 with an anodic potential of 1.33V vs. RHE. The anodic potential remained below typical OER potentials even at high conversion. For the first time, we demonstrated that MOR can achieve significant formate yields at high current density. Our results reveal the impact of conversion, reaction conditions and ion balance on selectivity and provide valuable insights for operating MOR at high yield in paired processes, e.g., with hydrogen evolution or CO2 reduction.

Lipid analyses of oil-bearing biomass using a thermally induced derivatization method

This study assessed the efficacy of a commercial fatty acid (FA) methylation kit for analyzing insect/microalgal biomass lipids by comparing it to a thermally induced derivatization method, which is known for its high conversion yield and impurity resistance and serves as a benchmark for evaluating kit performance, as a comparative standard. In insect lipid analysis, kit-based derivatization demonstrated a lower yield of FA methyl esters (FAMEs) than that of the thermally induced method, which is attributable to inherent technical limitations (vulnerability to impurities). This yield discrepancy was further highlighted in microalgal lipid analyses. The efficiency of FA derivatization using the kit-based method was contingent on the lipid structure, as evidenced by the diminished conversion yields for wax esters in Euglena gracilis. Furthermore, for Chlamydomonas reinhardtii, the lower FAME yield observed with kit-based derivatization suggested potential inadequacies in lipid extraction, particularly in the presence of rigid cellular structures such as cell walls. This reduced interaction between lipids and methanol could lead to diminished FAME conversion yields. These findings highlight the notable influence of the biomass type and lipid structure on the efficiency of kit-based derivatization, potentially yielding suboptimal results in lipid analysis.

Hydrogen Production by Steam Reforming of Ethanol and Dry Reforming of Methane with CO2 on Ni/Vermiculite: Stability Improvement via Acid or Base Treatment of the Support.

In this study, vermiculite was explored as a support material for nickel catalysts in two key processes in syngas production: dry reforming of methane with CO2 and steam reforming of ethanol. The vermiculite underwent acid or base treatment, followed by the preparation of Ni catalysts through incipient wetness impregnation. Characterization was conducted using various techniques, including X-ray diffraction (XRD), SEM-EDS, FTIR, and temperature-programmed reduction (H2-TPR). TG-TD analyses were performed to assess the formation of carbon deposits on spent catalysts. The Ni-based catalysts were used in reaction tests without a reduction pre-treatment. Initially, raw vermiculite-supported nickel showed limited catalytic activity in the dry reforming of methane. After acid (Ni/VTA) or base (Ni/VTB) treatment, vermiculite proved to be an effective support for nickel catalysts that displayed outstanding performance, achieving high methane conversion and hydrogen yield. The acidic treatment improved the reduction of nickel species and reduced carbon deposition, outperforming the Ni over alkali treated support. The prepared catalysts were also evaluated in ethanol steam reforming under various conditions including temperature, water/ethanol ratio, and space velocity, with acid-treated catalysts confirming the best performance.

Creating value added nano silicon anodes from end-of-life photovoltaic modules: recovery, nano structuring, and the impact of ball milling and binder on its electrochemical performance

Recovery of silicon from end-of-life photovoltaic (PV) modules, purification, conversion to nano silicon (nano-Si), and subsequent application as an anode in lithium-ion batteries is challenging but can significantly influence the circular economy. Currently, a complete technology consisting of cross-contamination-free recovery of silicon wafers from end-of-life PV modules, a low-cost environmentally friendly purification process of the recovered PV silicon, a high yield conversion process of the recovered PV silicon into nano-Si, and its subsequent application in lithium-ion batteries is unavailable. This study provides a complete package including cross-contamination-free recovery, economical purification, reliable conversion to nano-Si, and efficient application of the end-of-life PV nano-Si in lithium-ion batteries. Hydrofluoric acid-free recovery and purification processes are demonstrated which can deliver large quantities of high-purity (≥ 99) silicon. In addition, the subsequent ball milling process produces very distinct nano-Si with different shapes and sizes. This study also creates a very effective nano-Si anode through in-situ crosslinking of water-soluble carboxymethyl cellulose and poly (acrylic acid) precursors. The integration of distinct PV nano-Si and water-soluble carboxymethyl cellulose-poly (acrylic acid) crosslink binder opens distinct possibilities to develop silicon-based practical anode for next generation low-cost lithium-ion batteries to power cell phones to electric vehicles.

Efficient enzymatic saccharification of agricultural wastes for the production of bioethanol, D-allulose and lactic acid

The demand for renewable resources to replace fossil fuels has increased. Fruit and agricultural wastes can be fermented to yield biofuels and biochemicals. However, the high cost of the feedstock and limitations of the catalytic process hinder the application of such wastes. Therefore, we aimed to develop an efficient enzymatic saccharification process, without pretreatment, for fruit and agricultural wastes. The conversion rate of the mixed agricultural wastes (MAW) to fermentable sugars was approximately 91 % after 24 h. The ethanol yield increased by 4.5 % after limonene removal. The D-allulose yield in the hydrolysate was 4.6 mg/mL at 4 °C and 3.3 mg/mL at 50 °C, whereas the fructose yield in the sugar medium was 13.2 mg/mL at 4°C, demonstrating a high conversion yield of 73.2 %. Lactic acid was produced at a conversion rate of approximately 67.4 %. Therefore, this study presents a novel approach of the biosynthesis of functional sugars and chemicals from waste biomass, introducing a cost-effective enzymatic saccharification process that bypasses pretreatment, thereby enabling the production of biofuels, biochemicals, and functional sugars and opening up a promising economic opportunity in the field.

Facile Peptide Macrocyclization and Multifunctionalization via Cyclen Installation.

Cyclen-peptide bioconjugates are usually prepared in multiple steps that require individual preparation and purification of the cyclic peptide and hydrophilic cyclen derivatives. An efficient strategy is discovered for peptide cyclization and functionalization toward lanthanide probe via three components intermolecular crosslinking on solid-phase peptide synthesis with high conversion yield. Multifunctionality can be conferred by introducing different modular parts or/and metal ions on the cyclen-embedded cyclopeptide. As a proof-of-concept, a luminescent Eu3+ complex and a Gd3+-based contrasting agent for in vitro optical imaging and in vivo magnetic resonance imaging, respectively, are demonstrated through utilizing this preparation of cyclen-embedded cyclic arginylglycylaspartic acid (RGD) peptide.

Copper(I) iodide catalyzed redistribution of aromatic carboxylic acids

Copper(I) iodide catalyzes the disproportionation of aromatic and heteroaromatic carboxylic acids to give dicarboxylic acids. Potassium furoate heated to 280 – 300 °C in the presence of 10 mol % CuI under carbon dioxide (40 bar) forms dipotassium 2,5-furandicarboxylate (2,5-FDCK), which is isolated as pure 2,5-dicarboxylic acid (2,5-FDCA) in up to 75 % isolated yield and in excellent selectivity over the regioisomeric 2,4-furandicarboxylate (92 % selectivity). Starting materials are recovered in experiments lacking CuI or with pressurized N2 replacing CO2, whereas high conversion and low yields of 2,5-FDCA are obtained with moderate CO2 pressures, suggesting several roles for carbon dioxide in the transformation. Similarly, potassium benzoate heated to 320 – 350 °C in the presence of 10 mol % CuI under carbon dioxide (40 bar) produces terephthalic acid after workup in up to 60 % yield.

A tailored deep eutectic solvent for high-yield conversion of poplar residues to bio-based building blocks at mild conditions

The generation of condensed compounds in a deep eutectic solvent (DES) pretreatment has become a paramount factor that inhibits the further conversion of pretreated cellulose-rich substrate. This study proposed a novel three-constituent DES system for the value-added utilization of poplar residues by efficiently suppressing hemicellulose derived condensation reactions. The results showed that adding ethanol into the DES system could effectively deconstruct the recalcitrant structure of poplar residues, simultaneously hindering the condensed composition formation. Under optimum ethanol addition (30%), the maximum xylan and lignin removal of 87.94% and 90.99% could be achieved, with more than 90.47% of glucan being preserved. With this, the glucan enzymatic hydrolysis efficiency was remarkably improved to 100% under the pretreatment conditions of 100 °C for 60 min, which was 84.69 times higher than the regular DES-pretreated poplar residues (1.17%). The working mechanism of relieving condensation reactions was characterized by Py-GC–MS, NMR, SEM, FTIR, and others. The results demonstrated that the addition of ethanol could regulate the degradation/conversion pathway of hemicellulose and lignin precipitation, thus inhibit the formation of condensed compounds during the pretreatment.

How To Get Isocyanate?

Isocyanate, a pivotal chemical intermediate to synthesize polyurethane with widespread applications in household appliances, automobiles, and construction, is predominantly produced via the phosgene process, which currently holds a paramount status in industrial isocyanate production. Nonetheless, concerns arise from the toxicity of phosgene and the corrosiveness of hydrogen chloride, posing safety hazards. The synthesis of isocyanate using nonphosgene methods represents a promising avenue for future development. This article primarily focuses on the nonphosgene approach, which involves the formation of carbamate through the reaction of nitro-amino compounds with carbon monoxide, dimethyl carbonate, and urea, among other reagents, subsequently leading to the thermal decomposition of carbamate to get isocyanate. This paper emphasizes the progress in catalyst development during the carbamate decomposition process. Single-component metal catalysts, particularly zinc, exhibit advantages such as high activity, cost-effectiveness, and compatibility with a wide range of substrates. Composite catalysts enhance isocyanate yield by introducing a second component to adjust the active metal composition. The central research direction aims to optimize catalyst adaptation to reaction conditions, including temperature, pressure, time, and solvent, to achieve high raw material conversion and product yield.

Sequential Co-Immobilization of Enzymes on Magnetic Nanoparticles for Efficient l-Xylulose Production.

Multi-enzymatic strategies have shown improvement in bioconversion during cofactor regeneration. In this study, purified l-arabinitol 4-dehydrogenase (LAD) and nicotinamide adenine dinucleotide oxidase (Nox) were immobilized via individual, mixed, and sequential co-immobilization approaches on magnetic nanoparticles, and were evaluated to enhance the conversion of l-arabinitol to l-xylulose. Initially, the immobilization of LAD or Nox on the nanoparticles resulted in a maximum immobilization yield and relative activity of 91.4% and 98.8%, respectively. The immobilized enzymes showed better pH and temperature profiles than the corresponding free enzymes. Furthermore, co-immobilization of these enzymes via mixed and sequential methods resulted in high loadings of 114 and 122 mg/g of support, respectively. Sequential co-immobilization of these enzymes proved more beneficial for higher conversion than mixed co-immobilization because of better retaining Nox residual activity. Sequentially co-immobilized enzymes showed a high relative conversion yield with broader pH, temperature, and storage stability profiles than the controls, along with high reusability. To the best of our knowledge, this is the first report on the mixed or sequential co-immobilization of LAD and Nox on magnetic nanoparticles for l-xylulose production. This finding suggests that selecting a sequential co-immobilization strategy is more beneficial than using individual or mixed co-immobilized enzymes on magnetic nanoparticles for enhancing conversion applications.

Oxidation of glycerol to dihydroxyacetone over highly stable Au catalysts supported on mineral-derived CuO-ZnO mixed oxide

Selective oxidation of glycerol to dihydroxyacetone (DHA) is a promising pathway for glycerol utilization. In order to fabricate a highly stable supported Au catalyst for the reaction, a series of CuO-ZnO mixed oxides derived from different minerals were synthesized. Then, the Au/CuO-ZnO catalysts were prepared by the deposition-precipitation. High yield of DHA (70%) and conversion of glycerol (76%) were obtained over the rosasite-derived Au/CuO-ZnO catalyst. While over the aurichalcite-derived Au/CuO-ZnO catalyst, the yield of DHA was only 20%. By means of XRD, H2-TPR, TEM, XPS, CO2-TPD characterization, it was found that the higher yield of DHA was attributed to the stronger interaction between CuO and ZnO, higher dispersion of Au species, higher content of Au0 and proper amount of surface basic sites. The rosasite-derived Au/CuO-ZnO catalyst also showed good stability and no obvious decrease in reactivity and DHA selectivity could be seen after five recycles. The stable structure of the support not only enhanced the interaction between CuO-ZnO that stabilized the support itself, but also improved the interaction between Au and the support, further stabilizing the particle size and chemical valence of Au.

Simulation of waste tire gasification in bubbling fluidized bed by Aspen: Contribution ratio analysis

Waste tire gasification in a bubbling fluidized bed is a promising thermochemical conversion technology that not only utilize waste tire but also produce energy. To reveal the gasification performance of waste tire in a bubbling fluidized bed, two Aspen models were developed to simulate the effect of gasification agent types (such as air, steam, carbon dioxide and their mixtures), considering chemical reactions that reached thermodynamic equilibrium (CRTM) or were controlled by kinetics (CRK). The simulated gas compositions (H2, CO, CO2 and CH4) and lower heating value (LHV) were compared with experimental data under various operating conditions. The results showed that CRK model exhibited much better performance than the CRTM model. These two models were further utilized to analyze the effect of gasification agent type on gas composition and LHV. The contribution ratios of different chemical reactions were detailed analyzed, such as hydrogen combustion, carbon monoxide combustion, methane combustion, carbon combustion, steam gasification, water gas shift reaction and carbon dioxide gasification. The established Aspen model for waste tire gasification in a bubbling fluidized bed could be served as a guideline for selecting operation conditions to achieve high hydrogen composition, carbon conversion, and gas yield.

Aqueous Activation of RNA 2'-OH for Conjugation with Amines and Thiols.

Strategies for covalent modification of RNA are important for enabling biological studies of the biopolymer and for enhancing properties of therapeutic RNAs. While a number of electrophiles have been observed to react with RNA, few methods exist for reaction with nucleophiles. Here, we describe new reagents that enable efficient conjugation of amines and other nucleophiles to unmodified RNA postsynthetically via transient activation of 2'-OH groups. Reaction of single-stranded RNA in aqueous solution with phenolic imidazolecarbamates at room temperature results in stoichiometric and superstoichiometric yields of imidazolecarbonyl group adducts, and control experiments with DNA confirm the site of reaction in RNA as 2'-OH. Subsequent incubation of imidazolecarbonyl-activated RNAs with primary or selected secondary amines results in rapid, high-yield conversion to carbamate conjugates. The activation and subsequent nucleophile reaction can be carried out either stepwise or in a one-pot reaction. Thiols and phenol species react to yield (thio)carbonate adducts, and amino acid sidechains also react, suggesting possible future utility for protein conjugates and analysis of protein-RNA interactions. The activation method is found to be selective to unpaired regions of RNA, and can be directed to a specific location in a strand by use of a loop-inducing helper DNA. The results establish novel and efficient reagents and methods for modifying RNA postsynthetically with nucleophiles.

Two-step physico-biological production of xylooligosaccharides from sugarcane leaves

The production of xylooligosaccharides (XOS) from sugarcane leaves (SCL) presents high potential to the nutraceutical industries as SCL are cheap and readily available. In this study, a two-step process using hydrothermal pretreatments and enzymatic hydrolysis are developed and optimized for XOS production to obtain high conversion yield and product specificity. Two operation methods for hydrothermal pretreatments, parr reactor, and microwave reactor were compared to extract xylan from SCL. Two hemicellulose enzymes, hemicellulase Amano and xylanase (X2753) were then tested for enzymatic hydrolysis of extracted xylan to XOS. Conditions with high conversion yield after pretreatments were found at 180 °C for 30 min (parr reactor) and 800 W for 8 min (microwave reactor): producing 4.95 mg/mL (22.11 %w/v) and 3.49 mg/mL (15.61 %w/v) XOS respectively. Subjection of derived liquor from hydrothermal pretreatment to enzymatic hydrolysis produced a maximum of 9.42 mg/mL (41.87 %w/v) and 7.81 mg/mL (34.71 %w/v) of XOS for hemicellulase Amano and xylanase (X2753) respectively. The hemicellulase resulted in XOS with degree of polymerization (DP) of 2–5 for the various pretreatment conditions whereas xylanase yielded XOS of DP 2 to 4. However, a negative effect on enzymatic hydrolysis was observed for microwave-assisted pretreated samples. This study revealed that combination of physico-biological methods on SCL could result in high XOS yield with distinct degree of polymerization.

Enhancing photocatalytic visible-light-driven oxidation of NOx over Mott-Schottky Ag/SnO2 nanorod heterojunctions

Nitrogen oxides (NOx) is formed by primary emission from diesel engine vehicles. In this study, we synthesized and applied the photocatalytic effect over Mott-Schottky Ag/SnO2 nanorod heterojunctions toward NOx removal under visible light. In detail, the presence of Ag NPs in the Ag/SnO2 nanorod heterojunction, the number of electrons participating in the catalysis is enhanced due to the localized surface plasmon resonance (LSPR) of Ag NPs. In addition, the potential of the reducing region of SnO2 is also changed, thereby creating favourable conditions for the photocatalysis. We determined that 1.5% Ag/SnO2 nanorod heterojunction is the best sample with NO (500 ppb) photodegradation efficiency of 50.64% under visible light irradiation. Moreover, Ag/SnO2 nanorod heterojunction has an excellent stability after undergoing five times recycling and is highly applicable in practical applications with a high NO degradation and low NO2 conversion yield. The Mott-Schottky plots, Tauc plots, and trapping tests were used to build the energy scheme of the Ag/SnO2 heterojunction.