Scale-up Experiments Research Articles

A Mn(II)-Catalyzed Tandem Oxidative Cleavage and Ammoxidation of Alcohols to Primary Amides

AbstractThe cleavage/functionalization of C–C bonds in alcohols has emerged as a robust tool for exploration of new conversion. Herein, a Mn(OAc)2-catalyzed oxidative cleavage/ammoxidation of a wide range of alcohols to amides has been developed. The practicality of this transformation was demonstrated by a scale-up experiment and an amidation of mixed alcohols in a one-pot fashion. Moreover, a plausible mechanism was proposed based on a series of control experiments.

Scale-up and fed-batch cultivation strategy for the enhanced co-production of microbial lipids and carotenoids using renewable waste feedstock

Agro-industrial by-product valorization as a feedstock for the bioproduction of high-value products has demonstrated a feasible alternative to handle the environmental impact of waste. Oleaginous yeasts are promising cell factories for the industrial production of lipids and carotenoids. Since oleaginous yeasts are aerobic microorganisms, studying the volumetric mass transfer (kLa) could facilitate the scale-up and operation of bioreactors to grant the industrial availability of biocompounds. Scale-up experiments were performed to assess the simultaneous production of lipids and carotenoids using the yeast Sporobolomyces roseus CFGU-S005 and comparing the yields in batch and fed-batch mode cultivation using agro-waste hydrolysate in a 7 L bench-top bioreactor. The results indicate that oxygen availability in the fermentation affected the simultaneous production of metabolites. The highest production of lipids (3.4 g/L) was attained using the kLa value of 22.44 h−1, while higher carotenoid accumulation of 2.58 mg/L resulted when agitation speed was increased to 350 rpm (kLa 32.16 h−1). The adapted fed-batch mode in the fermentation increased the production yields two times. The fatty acid profile was affected according to supplied aeration and after the fed-batch cultivation mode. This study showed the scale-up potential of the bioprocess using the strain S. roseus in the obtention of microbial oil and carotenoids by the valorization of agro-industrial byproducts as a carbon source.

Cascade Oxidative Trifluoromethylthiolation and Cyclization of 3-Alkyl-1-(2-(alkynyl)phenyl)indoles

Persulfate-promoted radical cascade trifluoromethylthiolation and cyclization of 3-alkyl-1-(2-(alkynyl)phenyl)indoles with AgSCF3 were investigated. This protocol provides a novel route to CF3S-substituted indolo[1,2-a]quinoline-7-carbaldehydes and CF3S-substituted indolo[1,2-a]quinoline-7-methanone derivatives via the formation of the C-SCF3 bond and C-C bond and benzylic carbon oxidation in a single step. This reaction can accommodate a broad range of functional groups. The single-crystal X-ray diffraction data confirm the chemical structure of the product. A scale-up experiment and radical inhibition experiments were operated in the reaction system. Photophysical properties of some selected 5-((trifluoromethyl)thio)indolo[1,2-a]quinoline-7-carbaldehydes were studied by UV-visible and fluorescence spectroscopy.

Copper-Catalyzed Asymmetric Dearomative [3+2] Cycloaddition of Nitroheteroarenes with Azomethines.

Catalytic asymmetric dearomative [3+2] cycloaddition of α-imino γ-lactones with either 3-nitroindoles or 2-nitrobenzofurans by using a chiral copper complex as the catalyst was developed. A wide range of structurally diverse polyheterocyclic compounds containing spirocyclic-fused butyrolactone-pyrrolidine-indoline and butyrolactone-pyrrolidine-dihydrobenzofuran skeletons could be smoothly obtained with excellent results (>99:1 dr and 98% ee). The potential synthetic applications of this methodology were also demonstrated by the scale-up experiment and by the diverse transformations of one product. This method is characterized by high asymmetric induction, wide functional group tolerance and scalability, and attractive product diversification.

Identification and hepatoprotective activity of total glycosides of paeony with high content of paeoniflorin extracted from Paeonia lactiflora Pall.

The aims of this work were to obtain total glucosides of paeony (TGP) with high content of paeoniflorin and evaluate the hepo-protective properties of TGP. After optimization by response surface methodology, optimized conditions were as follows: extraction time 33.0min, extraction temperature 48°C, ethanol content 44%, and the yield of TGP was 47.68mg/g. Moreover, under established macroporous resin purification, paeoniflorin content of TGP achieved 67.6% in 1.5L scale-up verification experiment. Purified TGP (p-TGP) was further analyzed by UHPLC-Q-Orbitrap-MS/MS, and 35 compouds including paeoniflorin were identified. The obtained p-TGP effectively reduced biochemical indexes and inflammatory cytokines in liver tissue of acute alcoholic liver injury mice model. Depending on this work, TGP with definitive compound composition exhibited great protective effect against acute alcoholic liver injury in vivo. Furthermore, the finding of this work will be helpful to understand the relationship between compound composition and functional properties of Chinese herb extracts.

Ln-substituted polytungstates as efficient hetergeneous catalysts for Knoevenagel condensation reaction

Three isomorphic polytungstates, Cs9K18H10{[Sm2(H2O)4W4O10(AsW9O33)3]2(N(CH2PO3)2)}·46.5H2O (1), Cs10K9H18{[Eu2(H2O)4W4O10(AsW9O33)3]2(N(CH2PO3)2)}·41.5H2O (2), Cs10K9H18{[Gd2(H2O)4W4O10 (AsW9O33)3]2(N(CH2PO3)2)}·46H2O (3), have been successfully synthesized and characterized by routine methods, and demonstrated excellent catalytic activities in Knoevenagel condensation reaction as heterogeneous catalysts. Notably, catalyst 1 achieved higher reaction activity than catalysts 2 and 3, where a satisfactory reaction yield (95%) and high TON value (6380) could be obtained at moderate reaction condition. In addition, in the scale-up experiment, with the help of catalyst 1, 7.8 g benzaldehyde and 5.7 g ethyl cyanoacetate could transform into corresponding condensation product with a satisfactory yield (83%) and impressive TON value (13,883).

Denitrification in bioretention systems based on corncob biochar produced at low pyrolysis temperature: The efficacy and the mechanisms

In this study, the performance of corncob biochar (CCB) produced at 250 °C, a relatively low temperature for biochar production, on nitrate removal was investigated under dynamic flow conditions based on bench column and scale-up bioretention device experiments. CCB could continuously release sufficient soluble organic compounds for denitrification. In the column experiment, the highest denitrification rate of 130.3 mg·N/(L·d) was observed at HRT of 8 h, which was much higher than the raw corncob. At the HRT of 8 h, the nitrate removal efficiency could maintain 100 % with the influent NO3–-N concentration not higher than 30 mg/L. The presence of CCB at a mass content of 5 % in the scale-up bioretention device could significantly improve the nitrate removal performance and there was barely accumulation of nitrite. The universal molecular characterization of the DOM based on FT-ICR MS showed that the DOM from CCB contained less proteins and more hydrophobic aromatic compounds than from the raw corncob, which was responsible for the prolonged and steady release of TOC and thus the better performance of denitrification for CCB. These results showed the potential of corncob biochar produced at low temperatures to apply to the bioretention facilities for urban stormwater management.

Open Loop Recycling - Guanidine Iron(II) Polymerization Catalyst for the Depolymerization of Polylactide.

A previously reported non-toxic guanidine-iron catalyst active in the ring opening polymerization (ROP) of polylactide (PLA) under industrially relevant conditions was evaluated for its activity in the alcoholysis and aminolysis of PLA under mild conditions. Kinetic and thermodynamic parameters were determined for the methanolysis of PLA with [FeCl2(TMG5NMe2asme)] (C1) using 1H NMR spectroscopy. A comparison with the Zn analog of C1 showed that the metal center has a large impact on the activity for the alcoholysis. Further, the influence of different nucleophiles was tested broadening the scope of products from PLA waste. C1 is the first discrete metal catalyst reported to be active in the selective aminolysis of PLA. Catalyst recycling, scale-up experiments and solvent-free alcoholysis were conducted successfully strengthening the industrial relevance and highlighting aspects of green chemistry. Moreover, the selective depolymerization of PLA in polymer blends was successful. C1 is a promising catalyst for a circular (bio)plastics' economy.

Direct Excitation of Aldehyde to Activate the C(sp2 )-H Bond by Cobaloxime Catalysis toward Fluorenones Synthesis with Hydrogen Evolution.

A new way to form fluorenones via the direct excitation of substrates instead of photocatalyst to activate the C(sp2 )-H bond under redox-neutral condition is reported. Our design relies on the photoexcited aromatic aldehyde intermediates that can be intercepted by cobaloxime catalyst through single electron transfer for following β-H elimination. The generation of acyl radical and successful interception by a metal catalyst cobaloxime avoid the use of a photocatalyst and stoichiometric external oxidants, affording a series of highly substituted fluorenones, including six-membered ketones, such as xanthone and thioxanthone derivatives in good to excellent yields, and with hydrogen as the only byproduct. This catalytic system features a readily available metal catalyst, mild reaction conditions and broad substrate scope, in which sunlight reaction and scale-up experiments by continuous-flow approach make the new methodology sustainable and amenable for potentially operational procedures.

Heterogenous carboxyl-functionalized bilayer ionic liquids/polyoxometalate catalysts for extractant-free oxidative desulfurization

Heterogenous carboxyl-functionalized bilayer ionic liquids/polyoxometalate catalysts were synthesized. The optimized catalyst SiO2(50 nm)-BiIL-PW(Keggin-type) was characterized via FT-IR, XRD, Raman, UV–vis-DRS, XPS, TG, SEM-EDX, TEM, contact angle and N2 adsorption/desorption. Characterization results illuminate that polyoxometalate anions are grafted successfully onto the surface of carrier. The catalyst exhibits good amphiphilicity for both sulphur-containing compounds and hydrogen peroxide. With optimized catalyst, 100% sulfur removal can all be achieved for four model fuels including less active BT using a 4:1 molar ratio of n(H2O2)/n(S) and a low temperature of 40 °C free of extractant, which could be attributed to the better quasi homogeneous microenvironment provided by bilayer ionic liquids. Reaction results demonstrate that polyoxometalate and carrier have significant effects on the catalytic activities. Keggin-type phosphotungstate and 50 nm silica are superior for the desulfurization. ICP-MS analysis and the characterizations of recovered catalyst show no significant leaching of catalytic active component. No decrease was observed in catalytic efficiency after the 8th cycle in scale-up experiments.

Mechanism and kinetics of silicothermic reduction of MoS2 for preparing ultra-fine grain MoSi2 powder

In this work, ultra-fine grain MoSi 2 powders were prepared via silicothermic reduction of MoS 2 using CaO as a desulfurizer, and the mechanism and kinetics were studied in detail. The FE-SEM images demonstrated that the as-prepared MoSi 2 particles inherited the macro morphology and size of molybdenum sulfide and were almost not affected by the particle size of Si powder. Additionally, it was found that desulfurization reaction between CaO and gaseous SiS was a strong exothermic reaction, resulting in growth of MoSi 2 grains and difficult separation of the target product MoSi 2 from desulfurization product in the scale-up experiment. To solve this problem, graphite powder or carbon felt was introduced between the sample and CaO, and the residual S content of the prepared MoSi 2 powder was about 0.14% and 0.16%, respectively. This work provides new insights into the preparation of ultra-fine grain MoSi 2 powder by silicothermic reduction of MoS 2 -based molybdenum source. • Ultra-fine grain (about 300 nm) MoSi 2 powders were prepared via silicothermic reduction of MoS 2 . • Reaction mechanism and kinetics were studied in detail. • The as-prepared MoSi 2 inherits the macro morphology and particle size of molybdenum source.

In situ CO2 capture and transformation into cyclic carbonates using flue gas

CO2 in flue gas is captured and simultaneously in situ transformed into cyclic carbonates using the PP1,4Br/ZnCl2. A scale-up experiment displays outstanding catalytic ability, leaving concentrations of CO2 as low as 600 ppm in the residual gas.

Construction of BiOIO3/AgIO3 Z-Scheme Photocatalysts for the Efficient Removal of Persistent Organic Pollutants under Natural Sunlight Illumination.

The efficient removal of persistent organic pollutants (POPs) in natural waters is vital for human survival and sustainable development. Photocatalytic degradation is a feasible and cost-effective strategy to completely disintegrate POPs at room temperature. Herein, we develop a series of direct Z-scheme BiOIO3/AgIO3 hybrid photocatalysts via a facile deposition-precipitation method. Under natural sunlight irradiation, the light intensity of which is ∼40 mW/cm2, a considerable rate constant of 0.185 min-1 for photodecomposing 40 mg/L MO is obtained over 0.5 g/L Bi@Ag-5 composite photocatalyst powder, about 92.5 and 5.3 times higher than those of pristine AgIO3 and BiOIO3. The photoactivity of Bi@Ag-5 for photodecomposing MO under natural sunlight illumination surpasses most of the reported photocatalysts under Xe lamp illumination. After natural sunlight irradiation for 20 min, 95% of MO, 82% of phenol, 78% of 2,4-DCP, 54% of ofloxacin, and 88% of tetracycline hydrochloride can be photodecomposed over Bi@Ag-5. Relative to the commercial photocatalyst TiO2 (P25), Bi@Ag-5 exhibits greatly higher photoactivity for the treatment of MO-phenol-tetracycline hydrochloride mixture pollutants in the scale-up experiment of 500 mL of solution, decreasing COD, TOC, and chromaticity value by 52, 19, and 76%, respectively, after natural sunlight irradiation for 40 min. The photodegradation process and mechanism of MO have been systematically investigated and proposed. This work provides an archetype for designing efficient photocatalysts to remove POPs.

Highly efficient fermentation of 5-keto-d-fructose with Gluconobacter oxydans at different scales

The global market for sweeteners is increasing, and the food industry is constantly looking for new low-caloric sweeteners. The natural sweetener 5-keto-D-fructose is one such candidate. 5-Keto-D-fructose has a similar sweet taste quality as fructose. Developing a highly efficient 5-keto-D-fructose production process is key to being competitive with established sweeteners. Hence, the 5-keto-D-fructose production process was optimised regarding titre, yield, and productivity. For production of 5-keto-D-fructose with G. oxydans 621H ΔhsdR pBBR1-p264-fdhSCL-ST an extended-batch fermentation was conducted. During fructose feeding, a decreasing respiratory activity occurred, despite sufficient carbon supply. Oxygen and second substrate limitation could be excluded as reasons for the decreasing respiration. It was demonstrated that a short period of oxygen limitation has no significant influence on 5-keto-D-fructose production, showing the robustness of this process. Increasing the medium concentration increased initial biomass formation. Applying a fructose feeding solution with a concentration of approx. 1200g/L, a titre of 545g/L 5-keto-D-fructose was reached. The yield was with 0.98g5-keto-d-fructose/gfructose close to the theoretical maximum. A 1200g/L fructose solution has a viscosity of 450mPa∙s at a temperature of 55°C. Hence, the solution itself and the whole peripheral feeding system need to be heated, to apply such a highly concentrated feeding solution. Thermal treatment of highly concentrated fructose solutions led to the formation of 5-hydroxymethylfurfural, which inhibited the 5-keto-D-fructose production. Therefore, fructose solutions were only heated to about 100°C for approx. 10min. An alternative feeding strategy was investigated using solid fructose cubes, reaching the highest productivities above 10 g5-keto-d-fructose/L/h during feeding. Moreover, the scale-up of the 5-keto-D-fructose production to a 150L pressurised fermenter was successfully demonstrated using liquid fructose solutions (745g/L). We optimised the 5-keto-D-fructose production process and successfully increased titre, yield and productivity. By using solid fructose, we presented a second feeding strategy, which can be of great interest for further scale-up experiments. A first scale-up of this process was performed, showing the possibility for an industrial production of 5-keto-D-fructose.

The effects of influent chemical oxygen demand and strigolactone analog concentration on integral biogas upgrading and pollutants removal from piggery wastewater by different microalgae-based technologies

Microalgae-based technologies are promising strategies for efficient wastewater treatment and biogas upgrading. In this study, three types of microalga-fungi/bacteria symbiotic systems stimulated with the strigolactone analog (GR24) were used to simultaneously remove nutrients from treated piggery wastewater and CO2 from biogas. The effects of initial concentrations of chemical oxygen demand (COD) and GR24 on nutrient removal and biogas upgrading were investigated. When the initial COD concentration was 1200 mg/L, the Chlorella vulgaris–Ganoderma lucidum–endophytic bacteria co-cultivation systems achieved the best photosynthetic performance and microalgae growth. Moreover, under the appropriate COD concentration (1200 mg/L), the highest nutrient/CO2 removal efficiencies were obtained. In addition, 10−9 M GR24 significantly accelerated nutrient/CO2 removal efficiencies. These findings provide a theoretical basis for scale-up experiments using microalgae-based technologies

Study on preparation of a novel needle coke heterogeneous electro-Fenton cathode for coking wastewater treatment

Coking wastewater is a major challenge in wastewater treatment because of its complex composition, high pollutant concentrations, and poor biodegradability. In this study, a novel electro-Fenton cathode was prepared from needle coke loaded with ferrous ions (Fe/NC/Ti) for use in a heterogeneous electro-Fenton system for coking wastewater treatment. The optimum preparation conditions of the electrode and the main factors affecting the treatment of coking wastewater were investigated. An effective method to reduce the energy consumption of the electro-Fenton system was sought by constructing variable current systems, and scale-up experiments were performed. When the catalyst-to-binder ratio was 3:1, Fe2+ loading was 2.5 %, and the calcination temperature was 400 °C, the Fe/NC/Ti cathode had the best catalytic effect. The chemical oxygen demand (COD) removal rate of the coking wastewater reached 97.7 %, and UV254 decreased from 0.163 to 0.037 under optimal conditions. The water was clarified and made transparent after the reaction. A series of characterizations confirmed that the Fe/NC/Ti cathode had good stability and electrochemical performance, and the electro-Fenton system constructed using the cathode degraded aromatic compounds in coking wastewater, such as phenols and cyclic macromolecular organic compounds, to small molecules and even caused full mineralization. The results of the scale-up experiment showed that the system had low energy consumption while maintaining high COD removal efficiency. Therefore, the Fe/NC/Ti cathode could be used as a potential solution to address the limitations of the traditional electro-Fenton process for coking wastewater degradation.

Steam-driven crystalline-amorphous coupling design of homogenous metal hydroxides for oxygen evolution reaction

The crystalline-amorphous (c-a) structure is emerging as a promising design of oxygen evolution electrocatalysts. However, homogenous compositions and excellent stability are hindering further industrial applications. Only by using metal nitrates and methanol solvent, we provide an effective steam-driven strategy to directly fabricate c-a electrocatalysts. The division of methanol molecules establishes an experimental approach to analyze the targeted transformation from crystalline to c-a phase for monometallic nickel hydroxy-nitrates. Following, this design is successfully extended to the bimetallic NiFe layered double hydroxide (NiFe-LDH). The presence of Fe3+ not only effectively promotes electrochemical activity but also enhances adhesion to the nickel foam, conjuring up an ultra-active and ultra-stable NiFeA-S@NF electrocatalyst with an overpotential of 205 mV at 10 mA cm-2 and excellent 200 h stability at 500–1000 mA cm-2. In light of the above findings and preliminary scale-up experiment, this approach offers both fundamental and practical guidelines for other non-noble-metal-based electrocatalysts.

Phenylboronic acid functionalized polyacrylonitrile fiber for efficient and green synthesis of bis(indolyl)methane derivatives

The use of fiber as a catalyst carrier to construct heterogeneous catalysts with good catalytic activity and recycling performance has received wide attention. In this study, three phenylboronic acid functionalized polyacrylonitrile fiber (PANF) catalysts were synthesized by amination and quaternization. Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to verify the successful grafting of phenylboronic acid and the structural integrity of the fiber catalyst after recycling. The activity of the catalysts was explored with the Friedel–Crafts alkylation between indole and aromatic aldehydes. The results indicate that the synthesized catalyst (PAN p -BA F) in which the phenylboronic acid functional group was linked at the para position, exhibited the highest catalytic activity for the Friedel–Crafts alkylation. The substrate scope experiments confirmed that the catalyst has outstanding catalytic activity for most aromatic aldehydes, especially for those containing moderate electron donating groups. Moreover, the catalyst can be reused eight times in water without significant decrease in its catalytic activity. Further, the scale-up experiment confirmed that the fiber catalyst has a certain potential for industrial application.

UiO-66(Zr/Ti) for catalytic PET polycondensation

PET (poly(ethylene terephthalate)) is one of the most important type of thermoplastic polyesters and widely used in various fields. Titanium-based catalysts are environmentally friendly and have higher catalytic activity than antimony-based catalysts when used in industry. However, titanium-based catalysts are prone to hydrolysis and result in discolored products. UiO-66 (Zr/Ti) with different Ti4+ contents were successfully synthesized via one-step method. The material was characterized by XRD, SEM, FT-IR, XPS, BET and TG techniques. The results demonstrates that Ti4+ was integrated into the UiO-66 framework. NH3-in situ DRIFTS, pyridine-IR, and NH3-TPD were used to explore the acidic properties of the samples, which proved that stable Lewis acidic sites are present in the samples even at 300 °C. The catalytic performance of UiO-66 (Zr/Ti) containing different Ti4+ was explored under different conditions. At the same time, the scale-up experiment was carried out in a 5 L reactor, and the PET chips obtained had a lower b value. The catalytic reaction mechanism of UiO-66(Zr/Ti) was demonstrated by DFT calculations and the catalytic performance was close to Sb-based catalysts.

Improving calcium citrate food functions through spherulitic growth in reactive crystallization and a mechanism study

Calcium citrate, a high-end daily calcium supplement, whose irregular particle morphology leads to poor powder properties, limited food functions, and paste-like suspension problems. This study prepared the spherical calcium citrate by investigating four aspects of this reactive process: side reaction, crystallization, agglomeration, and fragmentation. Consequently, a concentration-dependent spherulitic growth operating space was established, in which reactive crystallization followed the second-category spherulitic growth mechanism depending on supersaturation. Besides, the temperature, stirring rate, and residence time were critical parameters for regulating the spherulite shape and size. These spherulites exhibited improved flowability and tabletability as calcium fortification ingredient, it also had a smoother and more pleasant texture. Furthermore, the micronized spherical powder showed high suspension stability as a calcium supplement during brewing. These spherical particles did not form paste-like suspension. Finally, the success of the scale-up experiments in semi-batch mode raised the possibility of industrialization of spherical calcium citrate.