High Conversion Yield Research Articles

Organic acid catalyzed production of platform chemical 5-hydroxymethylfurfural from fructose: Process comparison and evaluation based on kinetic modeling

Fructose was converted to 5-hydroxymethylfurfural (HMF), an important biomass-derived platform chemical, under mild conditions (100–130 °C) with several organic acids including p-toluene sulfonic (pTSA), oxalic, maleic, malonic and succinic acids as the catalysts. The process kinetics was compared considering fructose dehydration to HMF as the objective reaction and condensation of fructose and HMF to humin and rehydration of HMF as the main side reactions. DMSO was found to be the most effective solvent reaction medium to obtain high fructose conversion and HMF yield. Observed kinetic modeling illustrated that the rehydration and condensation of HMF in DMSO actually could be neglected, especially for the oxalic acid catalyzed system. The determined observed activation energy for fructose conversion to HMF and humin in DMSO medium was 33.75 and 24.94 kJ/mol for pTSA catalyzed system, and 96.51 and 78.39 kJ/mol for oxalic acid-catalyzed system, respectively. HMF yields of 90.2% and 84.1% were obtained for pTSA and oxalic acid catalyzed systems, respectively.

Efficient conversion of nitrogen to nitrogen-vacancy centers in diamond particles with high-temperature electron irradiation

Fluorescent nanodiamonds containing negatively-charged nitrogen-vacancy (NV−) centers are promising for a wide range of applications, such as for sensing, as fluorescence biomarkers, or to hyperpolarize nuclear spins. NV− centers are formed from substitutional nitrogen (P1 centers) defects and vacancies in the diamond lattice. Maximizing the concentration of NVs is most beneficial, which justifies the search for methods with a high yield of conversion from P1 to NV−. We report here the characterization of surface cleaned fluorescent micro- and nanodiamonds, obtained by irradiation of commercial diamond powder with high-energy (10 MeV) electrons and simultaneous annealing at 800 ∘C. Using this technique and increasing the irradiation dose, we demonstrate the creation of NV− with up to 25% conversion yield. Finally, we monitor the creation of irradiation-induced spin-1 defects in microdiamond particles, which we associate with W16 and W33 centers, and investigate the effects of irradiation dose and particle size on the coherence time of NV−.

Amylosucrase from Deinococcus geothermalis can be modulated under different reaction conditions to produce novel quercetin 4′-O-α-d-isomaltoside

Amylosucrase (ASase, EC.4.2.1.4) is well-known for its distinguishable property of transglycosylation of many flavonoids and phenolics. Quercetin has diverse biological functions, however, its use is limited due to poor solubility and bioavailability. ASase derived from Deinococcus geothermalis (DGAS) showed conditional preference for producing unusual quercetin glucosides (QGs). DGAS produced a variety of QGs including quercetin monoglucosides (QG1), diglucosides (QG2 and QG2′), and triglucoside from quercetin and sucrose. The newly synthesized QG2′ was recognized as a novel quercetin isomaltoside with an α-1,6 linkage branched at the −OH of C4′ in quercetin by mass and nuclear magnetic resonance spectra. With a higher conversion yield from quercetin to QGs (60–92%), the optimum conditions for producing QG2′ were examined under various pH and sucrose concentrations by response surface methodology. QG2′ was predominantly produced under acidic conditions (pH 5.0) and at high sucrose concentrations (1000–1500 mM). In contrast, QG1 was generated as an intermediate of consecutive glycosylation. Kinetic evaluations indicated that considerable differences of transglycosylation velocities were caused by the pH and buffer salts of the reaction, which had a 3.9-fold higher overall performance (kcat/K′m) of generating QG2′ at pH 5 compared to at pH 7. A rationale of unusual transglycosylations was demonstrated with a molecular docking simulation. Taken together, our study demonstrated that ASase can be used to synthesize unusually branched flavonoid glycosides from flavonol aglycones with clear patterns by modulating reaction conditions.

Cu/CuO Composite Track-Etched Membranes for Catalytic Decomposition of Nitrophenols and Removal of As(III).

One of the promising applications of nanomaterials is to use them as catalysts and sorbents to remove toxic pollutants such as nitroaromatic compounds and heavy metal ions for environmental protection. This work reports the synthesis of Cu/CuO-deposited composite track-etched membranes through low-temperature annealing and their application in catalysis and sorption. The synthesized Cu/CuO/poly(ethylene terephthalate) (PET) composites presented efficient catalytic activity with high conversion yield in the reduction of nitro aryl compounds to their corresponding amino derivatives. It has been found that increasing the time of annealing raises the ratio of the copper(II) oxide (CuO) tenorite phase in the structure, which leads to a significant increase in the catalytic activity of the composites. The samples presented maximum catalytic activity after 5 h of annealing, where the ratio of CuO phase and the degree of crystallinity were 64.3% and 62.7%, respectively. The catalytic activity of pristine and annealed composites was tested in the reduction of 4-nitroaniline and was shown to remain practically unchanged for five consecutive test cycles. Composites annealed at 140 °C were also tested for their capacity to absorb arsenic(III) ions in cross-flow mode. It was observed that the sorption capacity of composite membranes increased by 48.7% compared to the pristine sample and reached its maximum after 10 h of annealing, then gradually decreased by 24% with further annealing.

Catalytic Activity of Mixed Al2O3-ZrO2 Oxides for Glucose Conversion into 5-Hydroxymethylfurfural

In the present work, a series of catalysts based on aluminum and zirconium oxides was studied for the transformation of glucose into 5-hydroxymethylfurfural. These catalysts were characterized by using experimental techniques, such as X-ray diffraction, N2 adsorption–desorption at −196 °C, X-ray photoelectron spectroscopy, temperature-programmed desorption of NH3 and CO2, and scanning transmission electron microscopy. The catalytic behavior in glucose dehydration was evaluated in a water-methyl isobutyl ketone biphasic system, in the presence of CaCl2, in order to minimize losses due to unwanted secondary reactions. High glucose conversion and 5-hydroxymethylfurfural (HMF) yield values were obtained in the presence of an Al(Zr)Ox catalyst with an Al:Zr molar ratio of 7:3, reaching 97% and 47%, respectively, at 150 °C after 120 min. Under tested conditions, this catalyst retained most of its catalytic activity for four reuses.

Porcine pancreas lipase as a green catalyst for synthesis of bis-4-hydroxy coumarins

4-Hydroxycoumarins represents an important structural motif in life sciences molecules with remarkable biological properties. 4-Hydroxycoumarins are important precursors in the synthesis of organic compounds and critical pharmacophores in medicinal chemistry. One of the derivatives of this compound is biscoumarin, which has anticoagulant medicinal properties. Porcine pancreas lipase (PPL) has been used as an efficient green biocatalyst for the synthesis of bis-4-hydroxycoumarin compounds and expands the biocatalytic promiscuity of lipase in organic synthesis. Some aromatic aldehydes have been used in this investigation for screening and examining the ability of enzyme in knoevenagel condensation. Various parameters including temperature, solvent, and the amount of biocatalyst were investigated, ethanol, 45 °C and 10 mg of PPL gave rise to best yields. Bis-4-hydroxy coumarin compounds were synthesized under mild reaction conditions with high conversion yields (81–88%).

Outstanding hydrogen production properties of surface catalysts promoted Mg–Ni–Ce composites at room temperature in simulated seawater

The as-cast magnesium–nickel–cerium (Mg–Ni–Ce) alloys with nominal component (Mg–10 wt% Ni)1−xCex (x = 0, 5, 10, 15 wt%) are optimized by high-energy ball milling (HEBM). Expandable graphite (EG) and molybdenum disulfide (MoS2) have been introduced as surface catalysis to form (Mg10Ni)95Ce5–5 wt% EG–5 wt% MoS2 composite. The synergetic effects of HEBM and catalysts on H2 production of (Mg10Ni)95Ce5 are comprehensively studied. The thermodynamics are studied by H2 generation curves fitting. The HEBM 0Ce, 5Ce, 10Ce and 15Ce alloys at 291 K can generate 530, 747, 720 and 487 mL g−1 H2 with conversion yields of 59%, 87%, 89% and 64% in initial 15 min, respectively. The addition of surface catalysts EG–MoS2 can further enhance the initial hydrogen generation rate and the final conversion yield within short period at room temperature. 773 mL g−1 H2 corresponding to 95% conversion yield can be obtained by HEBM (Mg10Ni)95Ce5–EG–MoS2 within 1 min at 291 K. The synergetic effects of HEBM and EG–MoS2 can promote rapid initial generation rate and high conversion yield of hydrolysis hydrogen generation of (Mg10Ni)95Ce5–EG–MoS2 composite. This work indicates a promising way to synthesize Mg-based alloys with rapid initial hydrolysis H2 generation kinetics and high conversion yield within a short period.

Conversion Efficiencies of a Few Living Microbial Cells Detected at a High Throughput by Droplet-Based ESI-MS.

The label-free and sensitive detection of synthesis products from single microbial cells remains the bottleneck for determining the specific turnover numbers of individual whole-cell biocatalysts. We demonstrate the detection of lysine synthesized by only a few living cells in microfluidic droplets via mass spectrometry. Biocatalyst turnover numbers were analyzed using rationally designed reaction environments compatible with mass spectrometry, which were decoupled from cell growth and showed high specific turnover rates (∼1 fmol/(cell h)), high conversion yields (25%), and long-term catalyst stability (>14h). The heterogeneity of the cellular reactivity of only 15 ± 5 single biocatalysts per droplet could be demonstrated for the first time by parallelizing the droplet incubation. These results enable the resolution of biocatalysis beyond averages of populations. This is a key step toward quantifying specific reactivities of single cells as minimal functional catalytic units.

Influence of fatty acid composition on process optimization and characteristics assessment of biodiesel produced from waste animal fat

ABSTRACT This present study focus on the process optimization and characteristic assessment of waste animal fat (WAF) biodiesel based on the influence of fatty acids characterized in it. WAFs were rendered from leather fleshing (subcutaneous fat, 85.64%) and slaughterhouse (intramuscular fat, 8.46%) wastes using dry rendering technique, wherein the maximum renderable fat content was found to be 75.77% and 5.89%, respectively. Ethyl esters of oleic acid, palmitic acid, and stearic acid were characterized as dominant fatty acid esters (FAEs) in WAF biodiesel. Optimized transesterification on waste fats using ethanol and synthesized D-valine amido ethyl methyl imidazolium chloride ([D-Vaemim]Cl) as novel ionic liquid (IL) catalyst yielded 97.36% of biodiesel. High molar ratio (WAF to ethanol:6) and reaction temperature (75°C) were accounted by the long-chain fatty acids in triglyceride molecules and their higher degree of saturation, respectively, meanwhile, [D-Vaemim]Cl exhibited high conversion yield beyond 10% and was effective up to 10 cycles. Similarly, biodiesel properties were evaluated as per ASTM D6751 standards, were found to be in acceptable range, and were deeply influenced by carbon chain length and degree of unsaturation in FAE molecules. Also, the presence of long-chain saturated FAEs along with fuel bound oxygen induced superior combustion characteristics and controlled emission concentrations. However, slight reduction in engine performance was due to high viscosity and reduced calorific value of biodiesel which was reflected from its FAE molecules.

Stable Continuous Production of γ-Valerolactone from Biomass-Derived Levulinic Acid over Zr–Al-Beta Zeolite Catalyst

The one-pot conversion of biomass-derived platform molecules such as levulinic acid (LA) and furfural (FAL) into γ-valerolactone (GVL) is challenging because of the need for adequate multi-functional catalysts and high-pressure gaseous hydrogen. As a more sustainable alternative, here we describe the transfer hydrogenation of LA to GVL using isopropanol as a hydrogen donor over a Zr-modified beta zeolite catalyst in a continuous fixed-bed reactor. A stable sustained production of GVL was achieved from the levulinic acid, with both high LA conversion (ca. 95%) and GVL yield (ca. 90%), for over at least 20 days in continuous operation at 170 °C. Importantly, the small decay in activity can be advantageously overcome by the means of a simple in situ thermal regeneration in the air atmosphere, leading to a complete recovery of the catalyst activity. Key to this outstanding result is the use of a Zr-modified dealuminated beta zeolite with a tailored Lewis/Brønsted acid sites ratio, which can synergistically catalyze the tandem steps of hydrogen transfer and acid-catalyzed transformations, leading to such a successful and stable production of GVL from LA.

Methane-to-aromatics in a gas recycle methane reactor/hydrogen membrane separator

Direct non-oxidative methane conversion (DNMC) is one of the most promising options to convert methane (CH4) in natural gas in remote extraction sites to liquid aromatics, which is easier to transport compared to CH4 gas. The main constraint of the DNMC is low CH4 conversion, and thus aromatics product yield due to thermodynamic limitation. This work reports a gas recycle CH4 reactor/hydrogen (H2) membrane separator to achieve high CH4 conversion and aromatics yield by circumventing the thermodynamic limitation. The DNMC took place over an iron/silica (Fe/SiO2) catalyst in a packed-bed reactor to produce C2 (i.e. ethane, ethylene and acetylene) and aromatics, along with reaction product H2. The product stream passed through a condenser to collect aromatic products and then a H2-permeable membrane separator to remove H2. The unreacted CH4, C2 products and H2 residual in the product stream were sent to the recycle loop for the next round of DNMC reaction and H2 removal. The results demonstrated that >90 % product selectivity toward aromatics and >50 % aromatics yield are achieved in the gas recycle CH4 reactor/ H2 membrane separator system.

Gas-phase dehydration of glycerol to acrolein over different metal phosphate catalysts

We conducted a comparative study of gas phase dehydration of glycerol to acrolein over aluminium phosphate, iron phosphate and nickel phosphate catalysts prepared by a simple replacement reaction method (AlP, FeP and NiP). The textural properties, acid amounts, acid types, and coke contents of the samples were studied. The results showed that all metal phosphate catalysts remained in an amorphous state. The glycerol conversion was proportional to the acid amount of metal phosphate catalyst in the glycerol dehydration reaction. Higher value of B/L was more likely to produce acrolein. Among the metal phosphate catalysts, FeP showed superior performance due to its suitable textural and acid properties. After 2 h on stream, high glycerol conversion (96%), acrolein selectivity (82%) and acrolein yield (79%) were achieved on the FeP catalyst at 280 °C. The catalyst deactivation was ascribed to carbon deposition on the catalyst surface blocking the active sites during the glycerol dehydration reaction.

Biocatalytic Production of a Potent Inhibitor of Adipocyte Differentiation from Phloretin Using Engineered CYP102A1.

In this study, we investigated an efficient enzymatic strategy for producing potentially valuable phloretin metabolites from phlorizin, a glucoside of phloretin that is rich in apple pomace. Almond β-glucosidase efficiently removed phlorizin's glucose moiety to produce phloretin. CYP102A1 engineered by site-directed mutagenesis, domain swapping, and random mutagenesis catalyzed the highly regioselective C-hydroxylation of phloretin into 3-OH phloretin with high conversion yields. Under the optimal hydroxylation conditions of 15 g cells L-1 and a 20 mM substrate for whole-cell biocatalysis, phloretin was regioselectively hydroxylated into 3.1 mM 3-OH phloretin each hour. Furthermore, differentiation of 3T3-L1 preadipocytes into adipocytes and lipid accumulation were dramatically inhibited by 3-OH phloretin but promoted by phloretin. Consistent with these inhibitory effects, the expression of adipogenic regulator genes was downregulated by 3-OH phloretin. We propose a platform for the sustainable production and value creation of phloretin metabolites from apple pomace capable of inhibiting adipogenesis.

UV‐Light Responsive and Self‐Healable Ethylene/Propylene Copolymer Rubbers Based on Reversible [4 + 4] Cycloaddition of Anthracene Derivatives

AbstractA series of pendant anthracene‐functionalized ethylene/propylene copolymer rubbers (EPRs) with UV‐light response and self‐healing properties are prepared in this work. The reversible crosslinked networks are achieved based on the highly reversible nature of [4 + 4] cycloaddition of anthracene derivatives. The reversible crosslinking process is characterized by UV–vis spectrophotometer, which gives a high conversion yield of ≈90% as well as the reversibility of ≈70%. This reversible reaction is successfully applied to the self‐healing of EPR material. The healing efficiency is evaluated quantitatively by tensile test measurement. In terms of stress at break, the healing efficiency of crosslinked EPR with anthracene content of 5.7 mol% can reach 82.9%. The anthracene‐functionalized EPR might have a potential prospect of application in self‐healing field.

Expendable Graphite as an Efficient Flame-Retardant for Novel Partial Bio-Based Rigid Polyurethane Foams

The rigid polyurethane foam (PU) is a versatile material, used especially for construction and household applications. The current situation demands a facile, cost-efficient, and greener approach for developing the polyurethanes from bio-derived materials. In this study, we present a novel bio-polyol synthesized using carvone, an extract from caraway, spearmint, or dill seeds via facile thiol-ene reaction. Our one-step reaction uses a UV irradiation to allow the room temperature conversion of the carvone to a high purity bio-polyol, as confirmed from the standard analytical characterizations. The hydroxyl number of 365 mg KOH/g close to its theoretical limit confirms the high conversion yield of the polyol for rigid PU synthesis. To overcome the flammability issues in PU, expandable graphite (EG) powder was used as an additive flame-retardant during the synthesis step. The resulting foams with EG maintained the uniform closed cell structure (>95%) with a high compression strength of 175 kPa. The addition of EG in PU results in the formation of a protective char layer during the flammability test and reduces the weight loss from 40.70% to 3.55% and burning time from 87 to 11 s. Our results confirm that the carvone-based polyol can be a novel alternative to the petroleum polyols for an industrial-scale application.

Cyanide Boosting Copper Catalysis: A Mild Approach to Fluorescent Benzazole Derivatives from Nonemissive Schiff Bases in Biological Media.

An application of nucleophilic cyclization and oxidation of nonemissive Schiff bases via cyanide boosting copper catalysis to synthesize fluorescent benzazole derivatives in high conversion yield is disclosed. This approach is highlighted by broad substrate scope, fast reaction time, and mild conditions and can efficiently proceed in living cells or Arabidopsis root tissues. Furthermore, this methodology can be applied for selective detection of Cu2+ and CN-.

Novel Flexible Electrochemical Microreactor and its Validation by Three Model Electrosyntheses

AbstractA novel flexible electrochemical microreactor has been developed. Flexibility is reached by a modular design, suitability for a broad process parameter range including high pressure operation, and accessibility of production scale. Selected reactor aspects have been validated by applying the reactor to three different electrosyntheses: synthesis of tailor‐made mixtures of paraffins by Kolbe electrolysis, cation flow method, and synthesis of peroxodicarbonate. High conversion rates, yields, selectivities, and Faraday efficiency levels have been observed, showing precise process control.

Knockout of secondary alcohol dehydrogenase in Nocardia cholesterolicumNRRL 5767 by CRISPR/Cas9 genome editing technology.

Nocardia cholesterolicum NRRL 5767 is well-known for its ability to convert oleic acid to 10-hydroxystearic acid (~88%, w/w) and 10-ketostearic acid (~11%, w/w). Conversion of oleic acid to 10-hydroxystearic acid and then to 10-ketostearic acid has been proposed to be catalyzed by oleate hydratase and secondary alcohol dehydrogenase, respectively. Hydroxy fatty acids are value-added with many industrial applications. The objective of this study was to improve the Nocardia cholesterolicum NRRL5767 strain by CRISPR/Cas9 genome editing technology to knockout the secondary alcohol dehydrogenase gene, thus blocking the conversion of 10-hydroxystearic acid to 10-ketostearic acid. The improved strain would produce 10-hydroxystearic acid solely from oleic acid. Such improvement would enhance the production of 10-hydroxystearic acid by eliminating downstream separation of 10-hydroxystearic acid from 10-ketostearic acid. Here, we report: (1) Molecular cloning and characterization of two functional recombinant oleate hydratase isozymes and a functional recombinant secondary alcohol dehydrogenase from Nocardia cholesterolicum NRRL5767. Existence of two oleate hydratase isozymes may explain the high conversion yield of 10-hydroxystearic acid from oleic acid. (2) Construction of a CRISPR/Cas9/sgRNA chimeric plasmid that specifically targeted the secondary alcohol dehydrogenase gene by Golden Gate Assembly. (3) Transformation of the chimeric plasmid into Nocardia cholesterolicum NRRL 5767 by electroporation and screening of secondary alcohol dehydrogenase knockout mutants. Two mutants were validated by their lack of secondary alcohol dehydrogenase activity at the protein level and mutation at the targeted 5’ coding region and the 5’ upstream at the DNA level. The knockout mutants offer improvements by converting added oleic acid to solely 10-hydroxystearic acid, thus eliminating downstream separation of 10-hydroxystearic acid from 10-ketostearic acid. To the best of our knowledge, we report the first successful knockout of a target gene in the Nocardia species using CRISPR/Cas9/sgRNA-mediated genome editing technology.

Expression and characterization of a CALB-type lipase from Sporisorium reilianum SRZ2 and its potential in short-chain flavor ester synthesis

A lipase from Sporisorium reilianum SRZ2 (SRL) with 73% amino acid sequence identity to Candida antarctica lipase B (CALB) was cloned and overexpressed in Pichia pastoris. The recombinant SRL showed a preference for short-chain p-nitrophenyl esters. It achieved maximum activity at pH 8.0 and 65°C for p-nitrophenyl hexanoate (C6) with Km and kcat/Km values of 0.14 mmol·L−1 and 1712 min−1 · mmol · L−1 at 30°C, respectively. SRL displayed excellent thermostability and pH stability, retaining more than 79% of its initial activity after incubation at 60°C for 72 h and 75% at pH 3 to 11 for 72 h. It also maintained most of its activity in the presence of inhibitors and detergents except sodium dodecyl sulfate, and it tolerated organic solvents. SRL was covalently immobilized and successfully used for ethyl hexanoate synthesis in cyclohexane or in a solvent-free system with a high conversion yield (> 95%). Furthermore, high conversion yield was also achieved for the synthesis of various short-chain flavor esters when high substrate concentrations of 2 mol · L−1 were applied. This study indicated that a CALB-type lipase from S. reilianum SRZ2 showed great potential in organic ester synthesis.

RF-ICP Thermal Plasma for Thermoplastic Waste Pyrolysis Process with High Conversion Yield and Tar Elimination

This paper demonstrates an RF thermal plasma pyrolysis reaction apparatus that achieves 89 wt.% reaction conversion yield with no tar content. The demonstrated experimental apparatus consists of a 1100 W RFVII Inc. (104 Church St, Newfield, NJ 08344, United States) @ 13.56 MHz RF thermal plasma generator, a Navio matching network, intelligent feedback controller, and an 8-turn copper RF-ICP torch embedded in a 12 L thermochemical reactor. The intelligent feedback controller optimizes the thermal performance based on feedback signals from three online gas analyzers: CO, CO2 and NOx. The feedback controller output signal controls the RF thermal plasma torch current that provides real-time temperature control. The proposed reaction system achieves precise temperature profiles for both pyrolysis and gasification as well as increases end-product yield and eliminates undesired products such as tar and char. The identified hydrocarbon liquid mixture is 90 wt.% gasoline and 10 wt.%. diesel. The 8-turn RF-ICP thermal plasma torch has an average heating rate of +35 °C/min and a maximum operating temperature of 2000 °C and is able to sustain stable flame for more than 30 min. The reaction operating parameters are (550–990 °C τ = 30 min for pyrolysis and (1300 °C τ = 1 sec) for the gasification process. The identified hydrocarbon liquid products are 90 wt.% of a n-butyl-benzene (C6H5C4H9) and oluene (C7H8) mixture with less than 10 wt.% decane diesel fuel (C10 H22). Comsol simulation is used to assess the RF-ICP thermal plasma torch’s thermal performance.