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In this study, an upflow anaerobic packed-bed reactor (UAPB) produced biobutanol from the main byproduct of biodiesel plants, commonly known as glycerol. Currently, butanol production is mostly limited to pure cultures and sterilized feedstocks. Using glycerol wastes from biodiesel production demands a new paradigm because sterilization is not economically feasible for the elevated amount of glycerol generated by the biodiesel industry. Different microbial consortia were evaluated as inoculum sources to convert glycerol to butanol. In the first stage, operations were carried out with an average organic loading rate (OLR) of 13 g COD L−1 d−1. Kefir grains, sucrose auto-fermentation consortium, and heat-treated anaerobic sludge produced 16.7, 48.5, and 12.8 mg of butanol per gram of chemical oxygen demand (COD), respectively. Besides butanol production, a significant amount of ethanol (241.5 mg g−1 COD), acetate (30.3 mg g−1 COD), and butyrate (183.4 mg g−1 COD) were generated with glycerol processed by sucrose auto-fermentation consortium. In the second stage, the organic loading rates of 6.5, 13.0, and 26.0 g COD L−1 d−1 were applied to the UAPB reactor inoculated with sucrose auto-fermentation consortium. The OLR of 13.0 g COD L−1 d−1 yielded the highest production of butanol (41.5 mg g−1 COD) and generated other valuable co-products such as butyrate (246.1 mg g−1 COD), acetate (37.3 mg g−1 COD), and propionate (19.6 mg g−1 COD). [ABSTRACT FROM AUTHOR]

Ammonia decomposition is a key technology for its use as a hydrogen carrier and in the recovery of H 2 from waste streams containing ammonia. The coupling of the catalytic decomposition of ammonia with an H 2 permeoselective membrane improves the process by mitigating thermodynamic constraints and producing a flux of high-purity hydrogen, not requiring further separation/purification. In this study, we compare the behaviour of an eggshell catalyst 1.3 wt % Ru/Al 2 O 3 catalyst in a packed bed reactor (PBR) and a packed bed membrane reactor (PBMR) using an ultrathin Pd membrane (3.4 μm). Tests were made at 11 bar(a) with a weight hourly space velocity of NH 3 in the 0.560–1.68 Lꞏg−1ꞏh−1 range and temperatures of 350–400 °C, e.g. milder conditions than the conventional ammonia cracking catalysts. Under optimised conditions (0.56 Lꞏg−1ꞏh−1, 400 °C, sweep gas flow 0.55 L min−1), the PBMR shows excellent performance, achieving NH 3 conversion, H 2 productivity and recovery factor of 99%, 47 mmol H2 ·g Ru −1·min−1, and 94.9%, respectively. PBMR increases by ∼50% the conversion rate compared to PBR. Without a sweep gas, PBMR performances are lower, even still higher than in PBR. For the first time, superior or comparable performance was demonstrated compared to similar systems using pure ammonia in terms of conversion, hydrogen recovery, H 2 productivity, and Ru utilisation. These results can be further enhanced with vacuum systems to convert diluted ammonia streams into high-purity hydrogen for small-scale distributed systems and can be extended to other reactions. • An egg-shell Ru/Al 2 O 3 with an ultra-thin Pd membrane achieved 99% NH 3 conversion at 400 °C in PBMR, outperforming PBR. • Ultra-thin Pd membranes and sweep gas allow 94.88% H 2 recovery factor by decomposition of diluted ammonia. • Dilute NH 3 can improve safety and decrease noble metal usage, offering economic and environmental benefits. [ABSTRACT FROM AUTHOR]

Flow biocatalysis has emerged as a promising technology for the sustainable production of chemicals. Multiple immobilized enzymes are often used as biocatalysts to perform enzymatic cascade reactions in flow biocatalytic systems. When designing packed‐bed reactors with multiple immobilized enzymes, the enzymes are distributed in porous particles, and the porous particles are distributed in catalyst zones. A recently developed methodology is extended for selecting spatial immobilization distributions in batch reactors to packed‐bed reactors. Mechanistic models are used to compare the three most basic designs for a packed‐bed reactor, i.e., mixed individually immobilized enzymes, separated individually immobilized enzymes, and mixed co‐immobilized enzymes. For first‐order microkinetics, the design with co‐immobilized enzymes was found to always outperform the other two. Separating individually immobilized enzymes in two zones was proven to outperform mixing them in one zone for any positive order reaction kinetic. [ABSTRACT FROM AUTHOR]

A commercial lipase from Rhizopus japonicus was activated and utilized for triglyceride (TG) modification for producing structured lipids via acidolysis of TGs and fatty acids. To activate the lipase, lipase powder was mixed with glass beads (GBs) in 1-dodecanol and then a buffer solution were added dropwise to form hydrated lipase aggregates. After removal of liquid phase in the mixuture, the residue consisting of hydrated lipases and GBs was lyophilized and then the hydration – aggregation-pretreated lipase loaded onto GBs was recovered. The acidolytic activity of the lipase was significantly enhanced after hydration – aggregation pretreatment, whereas untreated lipase exhibited little activity. The effects of the surface hydrophobicity, diameter, and amount of lipase loading on GBs on the acidolytic activity of the lipase were investigated. The optimal GBs and lipase loadings were 0.428 mm in diameter with a hydrophobic surface and 89.2 U/g-GB, respectively. Under these conditions, the lipase exhibited an 8-fold higher catalytic activity than that of the hydration – aggregation-pretreated lipase without GBs. Furthermore, continuous modification of olive oil with palmitic acid via acidolysis using the hydration – aggregation-pretreated lipase packed in a column reactor was achieved for 116 h. The half-life of the packed-bed reactor was 149 h. [Display omitted] ● Lyophilizing lipase aggregates with glass beads enhanced acidolytic activity. ● Activated lipase can modify olive oil with palmitic acid via acidolysis. ● A packed bed reactor was developed using the activated lipases. ● Water content affected activity and stability of lipase during continuous run. [ABSTRACT FROM AUTHOR]

The Mn-Fe oxide material possesses the advantages of abundant availability, low cost, and non-toxicity as an energy storage material, particularly addressing the limitation of sluggish reoxidation kinetics observed in pure manganese oxide. However, scaling up the thermal energy storage (TCES) system poses challenges to the stability of the reactivities and mechanical strength of materials over long-term cycles, necessitating their resolution. In this study, Mn-Fe granules were fabricated with a diameter of approximately 2 mm using the feasible and scalable drop technique, and the effects of Y2O3-stabilized ZrO2 (YSZ) and SiO2 doping, at various doping ratios ranging from 1–20 wt%, were investigated on both the anti-sintering behavior and mechanical strength. In a thermal gravimetric analyzer, the redox reaction tests showed that both the dopants led to an enhancement in the reoxidation rates when the doping ratios were in an appropriate range, while they also brought about a decrease in the reduction rate and energy storage density. In a packed-bed reactor, the results of five consecutive redox tests showed a similar pattern to that in a thermal gravimetric analyzer. Additionally, the doping led to the stable reduction/oxidation reaction rates during the cyclic tests. In the subsequent 120 cyclic tests, the Si-doped granules exhibited volume expansion with a decreased crushing strength, whereas the YSZ-doped granules experienced drastic shrinkage with an increase in the crushing strength. The 1 wt% Si and 2 wt% Si presented the best synthetic performance, which resulted from the milder sintering effects during the long-term cyclic tests. [ABSTRACT FROM AUTHOR]

In this study, an upflow anaerobic packed-bed reactor (UAPB) produced biobutanol from the main byproduct of biodiesel plants, commonly known as glycerol. Currently, butanol production is mostly limited to pure cultures and sterilized feedstocks. Using glycerol wastes from biodiesel production demands a new paradigm because sterilization is not economically feasible for the elevated amount of glycerol generated by the biodiesel industry. Different microbial consortia were evaluated as inoculum sources to convert glycerol to butanol. In the first stage, operations were carried out with an average organic loading rate (OLR) of 13 g COD L−1 d−1. Kefir grains, sucrose auto-fermentation consortium, and heat-treated anaerobic sludge produced 16.7, 48.5, and 12.8 mg of butanol per gram of chemical oxygen demand (COD), respectively. Besides butanol production, a significant amount of ethanol (241.5 mg g−1 COD), acetate (30.3 mg g−1 COD), and butyrate (183.4 mg g−1 COD) were generated with glycerol processed by sucrose auto-fermentation consortium. In the second stage, the organic loading rates of 6.5, 13.0, and 26.0 g COD L−1 d−1 were applied to the UAPB reactor inoculated with sucrose auto-fermentation consortium. The OLR of 13.0 g COD L−1 d−1 yielded the highest production of butanol (41.5 mg g−1 COD) and generated other valuable co-products such as butyrate (246.1 mg g−1 COD), acetate (37.3 mg g−1 COD), and propionate (19.6 mg g−1 COD).

Multiphasic reaction of bicarbonate hydrogenation to form formate using homogeneous Ru PNP pincer catalyst in a continuous flow tubular reactor is reported. The reaction system consists of three phases. Catalyst is dissolved in toluene while potassium bicarbonate is dissolved in water. The significance of efficient mixing among the organic phase, aqueous phase and gaseous hydrogen to improve hydrogenation reaction by using different inert packing materials is studied by operando visualization and also quantitatively discussed. The bicarbonate conversion of up to 67% is achieved after optimization of important reaction and reactor parameters. The designed reactor setup comprised of effective recycling system that recycles the catalyst with >99% activity. [ABSTRACT FROM AUTHOR]

The plasma catalytic valorization of gases, particularly CH4 and CO2, has gained increasing attention. Value‐added chemicals, such as syngas and ethene, can be formed under mild conditions when temperature‐decoupled plasma activation and multistep feasible catalytic conversion are combined. In this sense, efficient plasma–catalyst interaction is of key importance, for which, however, plasma catalysis, as an emerging technology, is still poorly studied, where new catalyst design and investigation took up the most effort. In this perspective work, the challenging but equally important plasma–catalyst interaction is discussed, comparatively analyzing which type of plasma, catalyst bed, is the most promising. Representative plasma catalytic systems with their characteristic features are summarized, where the intrinsic capability of fluidized‐bed dielectric barrier discharge (FB‐DBD) reactor to maximize the plasma–catalyst interaction is highlighted. Furthermore, ongoing research on FB plasma catalysis is reviewed, based on which the superiority of FB‐DBD to other candidates, especially the most widely used packed‐bed DBD reactor, is critically evaluated. In addition, the perspectives of FB‐DBD, including challenges and development potential, are discussed. [ABSTRACT FROM AUTHOR]

Esters are versatile compounds with a wide range of applications in various industries due to their unique properties and pleasant aromas. Conventionally, the manufacture of these compounds has relied on the chemical route. Nevertheless, this technique employs high temperatures and inorganic catalysts, resulting in undesired additional steps to purify the final product by removing solvent residues, which decreases environmental sustainability and energy efficiency. In accordance with the principles of "Green Chemistry" and the search for more environmentally friendly methods, a new alternative, the enzymatic route, has been introduced. This technique uses low temperatures and does not require the use of solvents, resulting in more environmentally friendly final products. Despite the large number of studies published on the biocatalytic synthesis of esters, little attention has been paid to the reactors used for it. Therefore, it is convenient to gather the scattered information regarding the type of reactor employed in these synthesis reactions, considering the industrial field in which the process is carried out. A comparison between the performance of the different reactor configurations will allow us to draw the appropriate conclusions regarding their suitability for each specific industrial application. This review addresses, for the first time, the above aspects, which will undoubtedly help with the correct industrial implementation of these processes. [ABSTRACT FROM AUTHOR]

Fructooligosaccharides, a low‐calorie alternative sweetener with prebiotic effects, can be synthesized from sucrose via enzymatic reactions. Recently, methods for producing novel fructooligosaccharides using free and immobilized Bacillus licheniformis RN‐01 levansucrase were developed at the laboratory scale. However, there was a need to apply engineering knowledge in production process design and scale‐up to develop and evaluate the feasibility of this technology in the industrial scale. In this paper, three different types of reactors for fructooligosaccharides production using B. licheniformis RN‐01 levansucrase were compared in terms of technical and economic aspects. The previously collected experimental data, including enzyme activities, immobilization yields, product yields, and material balances, were used to estimate the capital and operating costs of fructooligosaccharides production using (a) immobilized enzyme in a stirred‐tank reactor, (b) immobilized enzyme in a packed‐bed reactor, and (c) free enzyme in a stirred‐tank reactor. The technical issues in reactor design and operation were also evaluated. The results showed that, in terms of minimum product selling prices, the process using immobilized enzyme had more economic advantages than the process using free enzyme because the cost savings from enzyme purchasing could compensate the additional equipment and chemical costs in the enzyme immobilization process. The results could be a guideline for selecting suitable reactor types for fructooligosaccharides production and provide directions for further reactor design and development. [ABSTRACT FROM AUTHOR]

Abstract Background Continuous processing with enzyme reuse is a well-known engineering strategy to enhance the efficiency of biocatalytic transformations for chemical synthesis. In one-pot multistep reactions, continuous processing offers the additional benefit of ensuring constant product quality via control of the product composition. Bottom-up production of cello-oligosaccharides (COS) involves multistep iterative β-1,4-glycosylation of glucose from sucrose catalyzed by sucrose phosphorylase from Bifidobacterium adeloscentis (BaScP), cellobiose phosphorylase from Cellulomonas uda (CuCbP) and cellodextrin phosphorylase from Clostridium cellulosi (CcCdP). Degree of polymerization (DP) control in the COS product is essential for soluble production and is implemented through balance of the oligosaccharide priming and elongation rates. A whole-cell E. coli catalyst co-expressing the phosphorylases in high yield and in the desired activity ratio, with CdP as the rate-limiting enzyme, was reported previously. Results Freeze-thaw permeabilized E. coli cells were immobilized in polyacrylamide (PAM) at 37–111 mg dry cells/g material. PAM particles (0.25–2.00 mm size) were characterized for COS production (~ 70 g/L) in mixed vessel with catalyst recycle and packed-bed reactor set-ups. The catalyst exhibited a dry mass-based overall activity (270 U/g; 37 mg cells/g material) lowered by ~ 40% compared to the corresponding free cells due to individual enzyme activity loss, CbP in particular, caused by the immobilization. Temperature studies revealed an operational optimum at 30 °C for stable continuous reaction (~ 1 month) in the packed bed (volume: 40 mL; height: 7.5 cm). The optimum reflects the limits of PAM catalyst structural and biological stability in combination with the requirement to control COS product solubility in order to prevent clogging of the packed bed. Using an axial flow rate of 0.75 cm− 1, the COS were produced at ~ 5.7 g/day and ≥ 95% substrate conversion (sucrose 300 mM). The product stream showed a stable composition of individual oligosaccharides up to cellohexaose, with cellobiose (48 mol%) and cellotriose (31 mol%) as the major components. Conclusions Continuous process technology for bottom-up biocatalytic production of soluble COS is demonstrated based on PAM immobilized E. coli cells that co-express BaScP, CuCbP and CcCdP in suitable absolute and relative activities.

Photocatalysis is an advanced oxidation process that is an environmentally friendly option and one of the most critical technologies in green chemistry today. This work studied the upscaling of photocatalysis as a suitable process for wastewater treatment to remove emerging pollutants. For this purpose, unsupported and supported TiO2 photocatalysts were tested in the photodegradation of ciprofloxacin as a model molecule of an emerging wastewater component, using visible, UV radiation, and solar light. The suitability of TiO2 as a photocatalyst to decompose ciprofloxacin was confirmed in batch photoreactor under Visible and UV radiation, with degradation rates up to 90% after 30 min of irradiation and low adsorption values. TiO2 as a photocatalyst coated in glass support material at the packed bed photoreactor showed good photoactivity for emergent contaminants degradation (95%) under solar radiation. It has been possible to verify that the photocatalytic reactor system constitutes a viable process for eliminating emerging contaminants through environmentally sustainable treatments. Our results corroborate the possibility of degrading emerging contaminants by solar radiation using a packed bed photoreactor, providing a more effective option from a practical and economical point of view for wastewater effluent treatments. [ABSTRACT FROM AUTHOR]

The use of stereoselective phase-transfer catalysis as a reliable method for the enantioselective synthesis of optically active α-amino acid derivatives using achiral Schiff base esters has been well-developed in batch in the last 40 years. Recently, continuous flow technology has become of great interest in the academy and industry, since it offers safer process operating conditions and higher efficiency compared to a traditional batch processing. Herein, we wish to report the first example of enantioselective phase transfer benzylation of alanine Schiff base ester, under continuous flow conditions. Two different methodologies were investigated: a liquid-solid phase transfer catalytic benzylation using a packed-bed reactor and a liquid-liquid phase transfer catalytic benzylation in continuous stirred-tank reactors. Liquid-liquid phase transfer process in flow showed slightly better productivity than the batch process, while solid-liquid phase transfer benzylation proved much more advantageous in terms of productivity and space-time yield. Furthermore, continuous flow system allowed the isolation of benzylated product without any work up, with a significant simplification of the process. In both cases, phase transfer asymmetric benzylation promoted by Maruoka catalyst demonstrated high enantioselectivity of target quaternary amino ester in flow, up to 93% ee. [ABSTRACT FROM AUTHOR]

The scarcity of petroleum and concern over environmental problems has promoted the production of biodiesel from renewable sources. Biodiesel synthesized by transesterification methods in the presence of catalyst requires a large amount of solvent, mainly from alcohol, to affirm a high production yield. The transesterification process using a homogeneous catalyst demands complex product separation steps and is not recyclable; thus, it is economically unviable. In this study, transesterification reaction was conducted in a packed bed column using a heterogeneous catalyst, potash supported on PVA derived from the orange peel. Potash/PVA was characterized using Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). Potash-derived orange peel was supported on polyvinyl alcohol (PVA) to retain its mechanical stability. Optimization study revealed that a maximum biodiesel yield of 95.55% was obtained at an optimum temperature of 60 °C, 2.50 wt.% of catalyst and 12:1 of methanol: oil molar ratio. Potash derived from waste shows a promising alternative to produce a heterogeneous catalyst for biodiesel production. [ABSTRACT FROM AUTHOR]

Malolactic fermentation (MLF) is a challenging and time-consuming step in the winemaking process. The effects of climate change are making the intrinsic conditions in red wine more challenging for the growth of lactic acid bacteria through interfering with a prompt and effective MLF. However, this is a necessary process in red wine production that contributes to high quality of wine demanded by consumers. Previous studies in our group reported a highly efficient MLF of red wine by using encapsulated Oenococcus oeni. Here, we designed a bench-scale packed-bed reactor using encapsulated bacteria to facilitate and speed up this process. The time to complete MLF was reduced as the concentration of biocapsules increased. The system exhibited operational stability and efficiency in sequential batches of wine recirculated through the column. Furthermore, an efficient continuous MLF was achieved using the packed-bed reactor. In general, a slight reduction in the concentration of some volatile organic compounds (VOCs) in the wines from the continuous system was observed as compared to those from the recirculated system. [ABSTRACT FROM AUTHOR]

The hydrogen-rich gas produced in-situ by methanol steam reforming (MSR) reactions significantly affects the performance and endurance of the high-temperature polymer electrolyte membrane (HT-PEM) fuel cell stack. A numerical study of MSR reactions over a commercial CuO/ZnO/Al 2 O 3 catalyst coupling with the heat and mass transfer phenomena in a co-current packed-bed reactor is conducted. The simulation results of a 1D and a 2D pseudo-homogeneous reactor model are compared, which indicates the importance of radial gradients in the catalyst bed. The effects of geometry and operating parameters on the steady-state performance of the reactor are investigated. The simulation results show that the increases in the inlet temperature of burner gas and the tube diameter significantly increase the non-uniformity of radial temperature distributions in reformer tubes. Hot spots are formed near the tube wall in the entrance region. The hot-spot temperature in the catalyst bed rises with the increase in the inlet temperature of burner gas. Moreover, the difference in simulation results between the 1D and 2D models is shown to be primarily influenced by the tube diameter. With a methanol conversion approaching 100% or a relatively small tube diameter, the simplified 1D model can be used instead of the 2D model to estimate the reactor performance. [Display omitted] • Development of a 2D model for the MSR in a multi-tubular packed-bed reactor. • Comparison of simulation results between 1D and 2D reactor models. • Prediction of the temperature distribution inside a reactor tube. • Studying the effects of geometry and operating conditions on reformer performance. • Optimization of operating conditions for integration with a 5 kW HT-PEMFC stack. [ABSTRACT FROM AUTHOR]

Ethyl esters of omega-3 fatty acids are active pharmaceutical ingredients used for the reduction in triglycerides in the treatment of hyperlipidemia. Herein, an ultrasonic packed-bed bioreactor was developed for continuous production of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) ethyl esters from DHA+EPA concentrate and ethyl acetate (EA) using an immobilized lipase, Novozym® 435, as a biocatalyst. A three-level–two-factor central composite design combined with a response surface methodology (RSM) was employed to evaluate the packed-bed bioreactor with or without ultrasonication on the conversion of DHA + EPA ethyl ester. The highest conversion of 99% was achieved with ultrasonication at the condition of 1 mL min−1 flow rate and 100 mM DHA + EPA concentration. Our results also showed that the ultrasonic packed-bed bioreactor has a higher external mass transfer coefficient and a lower external substrate concentration on the surface of the immobilized enzyme. The effect of ultrasound was also demonstrated by a kinetic model in the batch reaction that the specificity constant (V′max/K2) in the ultrasonic bath was 8.9 times higher than that of the shaking bath, indicating the ultrasonication increased the affinity between enzymes and substrates and, therefore, increasing reaction rate. An experiment performed under the highest conversion conditions showed that the enzyme in the bioreactor remained stable at least for 5 days and maintained a 98% conversion. [ABSTRACT FROM AUTHOR]

A strategy for the immobilization of chiral 2,3‐bisaminocyclopropenium salt (pre‐catalyst) onto polystyrene and silica supports is presented together with a suitable procedure for the conversion into the corresponding cyclopropenimine superbase catalysts. The activity and recyclability of polystyrene‐ and silica‐supported cyclopropenimines were initially tested under batch conditions in a model Michael addition detecting comparable efficiencies but a superior stability of the latter heterogeneous catalyst (5 cycles, accumulated TON of 27.1). The preferred silica‐supported cyclopropenimine behaved very similarly to the soluble counterpart in the reaction of glycine imine with different Michael acceptors (48–92% yield; 60–98% ee) and it could be utilized as packing material for the fabrication of fixed‐bed mesoreactors (pressure‐resistant stainless‐steel columns). Continuous‐flow experiments were performed with satisfactory long‐term stability (24 h on stream) with unaltered conversion efficiency and enantioselectivity. [ABSTRACT FROM AUTHOR]

A model based on the Lattice Boltzmann method is developed to study the flow of reactive electro-kinetic fluids in porous media. The momentum, concentration and electric/potential fields are simulated via the Navier–Stokes, advection–diffusion/Nernst–Planck and Poisson equations, respectively. With this model, the total density and velocity fields, the concentration of reactants and reaction products, including neutral and ionized species, the electric potential and the interaction forces between the fields can be studied, and thus we provide an insight into the interplay between chemistry, flow and the geometry of the porous medium. The results show that the conversion efficiency of the reaction can be strongly influenced by the fluid velocity, reactant concentration and by porosity of the porous medium. The fluid velocity determines how long the reactants stay in the reaction areas, the reactant concentration controls the amount of the reaction material and with different dielectric constant, the porous medium can distort the electric field differently. All these factors make the reaction conversion efficiency display a non-trivial and non-monotonic behaviour as a function of the flow and reaction parameters. To better illustrate the dependence of the reaction conversion efficiency on the control parameters, based on the input from a number of numerical investigations, we developed a phenomenological model of the reactor. This model is capable of capturing the main features of the causal relationship between the performance of the reactor and the main test parameters. Using this model, one could optimize the choice of reaction and flow parameters in order to improve the performance of the reactor and achieve higher production rates. This article is part of the theme issue 'Progress in mesoscale methods for fluid dynamics simulation'. [ABSTRACT FROM AUTHOR]

Independent from their intended purpose, the understanding of structural characteristics of random packings of particles having defined shapes is important to understand and optimize fluid dynamic behaviour, heat, and mass transfer. The packing structure can be described by the coordination number, local porosity profiles, the average porosity, and pore characteristics, which are influenced by the wall and thickness effect; the material, shape, and size distribution of the packing particles; the packing and compaction mode; and the shape and material of the packing's containing walls. Therefore, existing knowledge on the structure of randomly packed mono‐sized particles is reviewed to provide an updated selection of relevant parameters and their derived correlations obtained by experimental, numerical, and analytical means. [ABSTRACT FROM AUTHOR]

A developing small‐scale reactor was examined using the principles of thermal engineering design. The thermodynamic state of the system, psychrometry, and gas dynamics of the moist gas were considered in order to evaluate the quality of the end use. The performance of the reactor was defined in terms of the upgraded fuel and the design parameters of the reactor. A ring‐die was used to pelletize a milled form of black pinecones. Commercial wood pellets (hog fuel) and raw pinecones were analyzed alongside processed pinecones for comparison. A morphological analysis of the processed feedstock was carried out using a field emission scanning electron microscope (FESEM) equipped with an Everhart–Thornley detector (ETD) and an energy dispersive spectroscope (EDS). Compared with wood and with raw pinecones, the relative yield of char derived from the processed pinecones increased by 109% and 198%, respectively. On the other hand, the oil yield from processed pine was 65% lower than from raw pinecones, and the oil yield was 57% lower than that from hog fuel. The gas equations for the producer gas derived from processed pinecones pellets, raw pinecones, and the wood pellets in the reactor are PV –0.013 = C, PV –0.024 = C and PV –0.020 = C, respectively. The dew point temperature of producer gas (processed pinecones) was found to have been reduced by 2–4%. The effect of sphericity on the processed pellets increased the pressure drop across the packed bed. © 2021 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

[Display omitted] • The utilization of DHBQ as a mediator in the Mediated fuel cell (MedFC). • The DHBQ reduced in a packed-bed reactor has been fed as an anodic fuel in MedFC. • 1.12 V of open circuit voltage and 282 mW/cm2 power have been obtained in MedFC. Hydrogen fuel cells, which produce electrical energy and only water as a byproduct, are evaluated for their use in eco-friendly technology. However, there are challenges with using abundant precious metal catalysts for electrodes, particularly regarding hydrogen gas crossover and managing the moisture of the polymer electrolyte membrane. To overcome these challenges, a mediated fuel-cell (MedFC) system, in which hydrogen fuel cells are combined with a redox-flow battery using an oxidation–reduction reaction of an electrolyte, has been recently developed. In a MedFC system, the reduced ions of redox-active materials generated by the oxidation of hydrogen in a packed-bed reactor are fed to the fuel cell electrode as a mediator. In this study, 2,5-dihydroxy1,4-benzoquinone (DHBQ) was used as a anode mediator to operate MedFCs under alkaline conditions. DHBQ and hydrogen were injected with an upward flow into the packed-bed reactor to reduce DHBQ via a chemical reaction. On the anode side of the fuel cell, DHBQ oxidized and transferred the electrons to the cathode. By contrast, an oxygen reduction reaction (ORR) occurred at the cathode under alkaline conditions. The reduction potential of DHBQ was −0.72 V (vs. SHE), and that of ORR was 0.4 V (vs. SHE); thus, the theoretical potential of the cell was 1.12 V. During the MedFC operation, a maximum power density of 282 mW/cm2 was obtained. [ABSTRACT FROM AUTHOR]

Advanced biotransformation processes typically involve the upstream processing part performed continuously and interlinked tightly with the product isolation. Key in their development is a catalyst that is highly active, operationally robust, conveniently produced, and recyclable. A promising strategy to obtain such catalyst is to encapsulate enzymes as permeabilized whole cells in porous polymer materials. Here, we show immobilization of the sucrose phosphorylase from Bifidobacterium adolescentis (P134Q-variant) by encapsulating the corresponding E. coli cells into polyacrylamide. Applying the solid catalyst, we demonstrate continuous production of the commercial extremolyte 2-α-d-glucosyl-glycerol (2-GG) from sucrose and glycerol. The solid catalyst exhibited similar activity (≥70%) as the cell-free extract (~800 U g−1 cell wet weight) and showed excellent in-operando stability (40 °C) over 6 weeks in a packed-bed reactor. Systematic study of immobilization parameters related to catalyst activity led to the identification of cell loading and catalyst particle size as important factors of process optimization. Using glycerol in excess (1.8 M), we analyzed sucrose conversion dependent on space velocity (0.075–0.750 h−1) and revealed conditions for full conversion of up to 900 mM sucrose. The maximum 2-GG space-time yield reached was 45 g L−1 h−1 for a product concentration of 120 g L−1. Collectively, our study establishes a step-economic route towards a practical whole cell-derived solid catalyst of sucrose phosphorylase, enabling continuous production of glucosides from sucrose. This strengthens the current biomanufacturing of 2-GG, but also has significant replication potential for other sucrose-derived glucosides, promoting their industrial scale production using sucrose phosphorylase. Key points: • Cells of sucrose phosphorylase fixed in polyacrylamide were highly active and stable. • Solid catalyst was integrated with continuous flow to reach high process efficiency. • Generic process technology to efficiently produce glucosides from sucrose is shown. [ABSTRACT FROM AUTHOR]

We report the on‐demand generation of hexane‐soluble (2‐ethylhexyl)sodium (1) from 3‐(chloromethyl)heptane (2) using a sodium‐packed‐bed reactor under continuous flow conditions. Thus, the resulting solution of 1 is free of elemental sodium and therefore suited for a range of synthetic applications. This new procedure avoids the storage of an alkylsodium and limits the handling of metallic sodium to a minimum. (2‐Ethylhexyl)sodium (1) proved to be a very useful reagent and undergoes in‐line Br/Na‐exchanges as well as directed sodiations. The resulting arylsodium intermediates are subsequently trapped in batch with various electrophiles such as ketones, aldehydes, Weinreb‐amides, imines, allyl bromides, disulfides and alkyl iodides. A reaction scale‐up of the Br/Na‐exchange using an in‐line electrophile quench was also reported. [ABSTRACT FROM AUTHOR]

This study is focused on investigating the dual performance of Rh/CeO 2 /γ-Al 2 O 3 catalyst for steam reforming of ethanol (SRE) and thermochemical water splitting (TCWS) using a packed bed reactor. The catalyst is designed to be thermally stable containing an active phase of Rh and the redox component of CeO 2 for oxygen exchange, supported on γ-Al 2 O 3. The catalyst has been characterised by SEM, XRD, BET, TPR, TPD, XPS and TGA before testing in the reactor. The optimal temperature for SRE reaction over this catalyst is between 700 °C and 800 °C to produce high concentrations of hydrogen (~60%), and low CO and CH 4. The selectivity towards CO and CH 4 is higher at low temperatures and drops with rise in reaction temperature. Further, Rh/CeO 2 /γ-Al 2 O 3 is found to be active for TCWS at relatively low temperatures (≤1200 °C). At temperatures as low as 800 °C, this catalyst is especially found suitable for multiple redox cycles, producing a total of 48.9 mmol/g cat in four redox cycles. The catalyst can be employed for large number of redox cycles when the reactor is operated at lower temperatures. Finally, the reaction pathways have been proposed for both SRE and TCWS on Rh/CeO 2 /γ-Al 2 O 3 catalyst. [Display omitted] • Thermochemical hydrogen production using stable and recyclable Rh/CeO 2 /γ-Al 2 O 3 catalyst. • Steam reforming of ethanol reaction produces ~67 vol% of hydrogen. • Thermochemical water splitting achieved at temperatures as low as 800 °C. • ~50 mmol of hydrogen produced per gram of the catalyst in four redox cycles. [ABSTRACT FROM AUTHOR]

Solar-driven photocatalysis is a promising water-cleaning and energy-producing technology that addresses some of the most urgent engineering problems of the twenty-first century: universal access to potable water, use of renewable energy, and mitigation of CO2 emissions. In this work, we aim at improving the efficiency of solar-driven photocatalysis by studying a novel reactor design based on microfluidic principles using 3D-printable geometries. The printed reactors had a dimensional accuracy of 97%, at a cost of less than $1 per piece. They were packed with 1.0-mm glass and steel beads coated with ZnO synthesised by a sol-gel routine, resulting in a bed with 46.6% void fraction (reaction volume of ca. 840 μL and equivalent flow diameter of 580 μm) and a specific surface area of 3200 m2 m−3. Photocatalytic experiments, under sunlight-level UV-A irradiation, showed that reactors packed with steel supports had apparent reaction rates ca. 75% higher than those packed with glass supports for the degradation of an aqueous solution of acetaminophen; however, they were strongly deactivated after the first use suggesting poor fixation. Glass supports showed no measurable deactivation after three consecutive uses. The apparent first-order reaction rate constants were between 1.9 and 9.5 × 10−4 s−1, ca. ten times faster than observed for conventional slurry reactors. The mass transfer was shown to be efficient (Sh > 7.7) despite the catalyst being immobilised onto fixed substrates. Finally, the proposed reactor design has the merit of a straightforward scaling out by sizing the irradiation window according to design specifications, as exemplified in the paper. [ABSTRACT FROM AUTHOR]

Pesticide-resistant plant pathogens are an increasing threat to the global food supply and have generated a need for novel, efficacious agrochemicals. The current regulatory process for approving new agrochemicals is a tedious but necessary process. One way to accelerate the safety evaluation process is to utilize in vitro systems to demonstrate pesticide degradation by soil microbes prior to ex vivo soil evaluations. This approach may have the capability to generate metabolic profiles free of inhibitory substances, such as humic acids, commonly present in ex vivo soil systems. In this study, we used a packed-bed microbial bioreactor to assess the role of the natural soil microbial community during biodegradation of the triazolopyrimidine fungicide, ametoctradin. Metabolite profiles produced during in vitro ametoctradin degradation were similar to the metabolite profiles obtained during environmental fate studies and demonstrated the degradation of 81% of the parent compound in 72 h compared to a half-life of 2 weeks when ametoctradin was left in the soil. The microbial communities of four different soil locations and the bioreactor microbiome were compared using high throughput sequencing. It was found that biodegradation of ametoctradin in both ex vivo soils and in vitro in the bioreactor correlated with an increase in the relative abundance of Burkholderiales, well characterized microbial degraders of xenobiotic compounds.

• A comparison CFD study of the different models for PBR hydrodynamics was conducted. • Six different approaches in the modelling of PBR hydrodynamics were compared. • An ordered and a randomly distributed resolved-particle model were developed. • Pseudohomogeneous models properly predict macroscopic behaviours. • Pseudohomogeneous cases cannot capture the local phenomena of resolved-particle cases. Despite the advances in the modelling of Packed-Bed Reactors (PBR) it is common to find in literature works where resolved-particle models are implemented considering small-scale domains; or works where large-scale models are implemented with a pseudohomogeneous approach. In order to quantify the differences in the prediction of the local velocity between these two approaches, a CFD study was conducted for the modelling of the single-phase flow in a PBR. Six different cases, two resolved-particle and four pseudohomogeneous, were implemented and compared. The resolved-particle cases incorporated the explicit description of the solids bed distribution, considering an ordered and a randomly distributed bed of spheres, in which the punctual momentum balance was solved in the interstitial void space left by the solids. The pseudohomogeneous cases considered Darcy's law (DL) and the Navier-Stokes-Darcy-Forchheimer (NSDF) equation, and the bed porosity as an overall average value ε B = ε B and as a function of the radial position of the bed ε B = ε B r , in order to include the effects of the solids bed without the explicit description of the solids distribution. The results show that there are significant local differences in the textural characteristics between the random packing and ordered packing for the resolved-particle cases. It was observed that the pseudohomogeneous models allow to predict the macroscopic behaviours indicated in the resolved-particle case, but fail to capture the local behaviours inside the bed. Furthermore, the inclusion of an average porosity distribution function does not improve the prediction of the local scale phenomena. [ABSTRACT FROM AUTHOR]

• A microfluidic packed-bed reactor for enzymatic synthesis of L-DOPA and dopamine is presented. • Single step production schemes for both L-DOPA and dopamine are presented, in addition to the complete cascade reaction. • A scale-up strategy to bench-top scale is demonstrated, with matching results between both the micro and macroscale approaches. • This type of system can be used to expedite process development in the future. Enzymatic synthesis of biochemical commodities is of upmost importance as it represents a greener alternative to traditional chemical synthesis and provides easier downstream processing strategies compared to fermentation-based processes. A microfluidic system used to optimize the enzymatic production of both levodopa (L-DOPA) and dopamine in both single-step and multistep-reaction sequences with yield of approximately 30 % for L-DOPA production and 70 % for dopamine production is presented. The system for L-DOPA production was then up-scaled (780-fold increase) to a milliliter scale system by maintaining similar mass transport properties resulting in the same yield, space-time yield and biocatalyst yield as its microscale counterpart. The results obtained for yield and biocatalyst yield (351.7 mg L-DOPA mg−1 Tyr h−1) were similar to what is reported in the literature for similar systems, however the space-time yield (0.806 mg L-DOPA L−1 h−1) was smaller. This work demonstrates a microfluidic bioreactor that can be used for complex optimizations that can be performed rapidly while reducing the consumption of reagents by immobilizing the catalyst on a carrier which can then be used in a packed-bed reactor, thus extending the enzyme life span. [ABSTRACT FROM AUTHOR]

• Fe(II)-driven autotrophic denitrification was investigated in packed-bed reactors. • Higher nitrate loading rates enhanced denitrification performances in PBR1. • The highest specific nitrate removal rate was 14.3 mg NO 3 −/g VS/h. • At constant nitrate loading rate, denitrification efficiency was stable in PBR2. • The Thiobacillus enriched mixed culture allowed a long-term process stability. Nowadays, nitrate represents one of the major contaminants of the hydrosphere, mainly affecting the quality of groundwater intended to the production of drinking water. This study proposes the use of Fe(II)-driven autotrophic denitrification as a high-potential, innovative bioprocess to couple microbially-catalyzed nitrate reduction to Fe(II) oxidation. Two identical up-flow packed bed reactors (PBRs), i.e. PBR1 and PBR2, with granular activated carbon as biofilm carrier were seeded with a Thiobacillus -mixed culture and operated for 153 days at different feed nitrate concentrations and hydraulic retention times (HRTs). The results show enhanced nitrate removal rates and efficiencies at increasing nitrate loading rates. In particular, nitrate removal and Fe(II) oxidation up to 85 and 95 %, respectively, were achieved in PBR1 at nitrate loading rates as high as 12.5 mg NO 3 −/L/h. Besides not undermining the denitrification efficiency, increasing the nitrate loading rate from 8.1 to 12.5 mg NO 3 −/L/h led to specific nitrate removal rates as high as 14.3 mg NO 3 −/g VS/h. In PBR2, Fe(II)-driven denitrification was investigated at a constant nitrate loading rate by concomitantly decreasing the feed nitrate concentration and HRT. Despite the less severe operational conditions, the use of lower nitrate loading rates resulted in a lower nitrate removal efficiency than that obtained in PBR1. [ABSTRACT FROM AUTHOR]

Pesticide-resistant plant pathogens are an increasing threat to the global food supply and have generated a need for novel, efficacious agrochemicals. The current regulatory process for approving new agrochemicals is a tedious but necessary process. One way to accelerate the safety evaluation process is to utilize in vitro systems to demonstrate pesticide degradation by soil microbes prior to ex vivo soil evaluations. This approach may have the capability to generate metabolic profiles free of inhibitory substances, such as humic acids, commonly present in ex vivo soil systems. In this study, we used a packed-bed microbial bioreactor to assess the role of the natural soil microbial community during biodegradation of the triazolopyrimidine fungicide, ametoctradin. Metabolite profiles produced during in vitro ametoctradin degradation were similar to the metabolite profiles obtained during environmental fate studies and demonstrated the degradation of 81% of the parent compound in 72 h compared to a half-life of 2 weeks when ametoctradin was left in the soil. The microbial communities of four different soil locations and the bioreactor microbiome were compared using high throughput sequencing. It was found that biodegradation of ametoctradin in both ex vivo soils and in vitro in the bioreactor correlated with an increase in the relative abundance of Burkholderiales, well characterized microbial degraders of xenobiotic compounds. [ABSTRACT FROM AUTHOR]

Lipases CAL-B, TLL, and RML were used in the synthesis of free fatty acids of grape seed oil as heterogeneous substrate. The best enzyme was used to optimize the reaction variables temperature, enzyme content, and molar ratio of water:oil in batch reactions using experimental planning. The ideal conditions to produce free fatty acids using pure RML were 45 °C, 12:1 substrate molar ratio, and 15% enzyme, resulting in 66% of oil hydrolysis and a productivity of 0.54 mol L−1 min−1 in 4 h of reaction at 180 rpm. Repeated batches of reaction were performed testing the operational stability of RML, results showing that this enzyme could be used for at least 20 cycles keeping more than 80% of its initial activity, suggesting its potential use in industrial processes. The synthesis of free fatty acids was then evaluated in continuous reactions using packed-bed reactor (PBR). The highest productivity in the continuous process was 6.85 mol L−1 min−1, using only RML, showing an operational stability higher than 80% of its initial conversion capacity after 11 days of operation, at a flow rate of 0.13 mL min−1 at 45 °C. We evaluated the use of this hydrolyzed oil as substrate for lactone bioproduction using Galactomyces geotrichum UFMG-CM-Y3276, G. geotrichum UFMG-CM-Y3558, and Geotrichum klebahnii UFMG-CM-Y3014 screened for their oil-hydrolysis ability. Volatile compounds were qualitatively identified in GC–MS as γ-octalactone and γ-nonalactone. [ABSTRACT FROM AUTHOR]

Interesterification reaction of palm oil and ethyl acetate for the synthesis of biodiesel was performed in a small-scale fixed-bed reactor. The reactor was packed with ion-exchange resin (RCP160M), which was used as catalyst for this work. The important factors affecting biodiesel content including reaction temperature, mass flow rate of reactants, and ethyl acetate-to-oil molar ratio were examined and optimized via the Box-Behnken design. Main effects and interactions of the variables on biodiesel content were addressed. The remarkable long-term stability of catalyst was also demonstrated for at least 72 h of continuous operation with relatively constant %FAEE. The optimal conditions yielding 99% of ester content were found as follows: reaction temperature of 113 °C, total mass flow rate of 5.4 × 10−4 kg/h, and ethyl acetate-to-oil molar ratio of 16.7:1. Considering the operating conditions and productivity parameter, this method could be further developed for efficient biodiesel production. [ABSTRACT FROM AUTHOR]

This study investigated the synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on magnetic poly(styrene-co-divinylbenzene) particles in a continuous packed-bed bioreactor. Runs were carried out in a solvent-free system at 50 °C. The performance of the reactor was evaluated for substrates composed by oleic acid and 2-ethylhexanol at five molar ratios (1:4–4:1), determining its operation limits in terms of substrate flow rate. The system performance was quantified for three different flow rates corresponding to space-time between 3 and 12 h. For each condition, the influence of the space-time in the ester formation, esterification yield and productivity was determined. The molar ratio of acid-to-alcohol interfered, in a remarkable way, in the formation of 2-ethylhexyl oleate and the best performance was attained for substrate at equimolar ratio running at 12 h space-time. Under this condition, average 2-ethylhexyl oleate concentration was 471.65 ± 2.98 g L−1 which corresponded to ester productivity of 23.16 ± 0.49 mmol g−1 L−1 h−1. This strategy also gave high biocatalyst operational stability, revealing a half-life time of 2063 h. A model based on the ping-pong Bi–Bi mechanism was developed to describe the kinetics of the esterification reaction and validated using experimental data. The goodness of fit of the model was satisfactory (R2 = 0.9310–0.9952). [ABSTRACT FROM AUTHOR]

The main objective of the study is to investigate the effect of hydraulic retention times on continuous dark fermentative biohydrogen production in an up-flow packed bed reactor (UPBR) containing a novel microorganism immobilization material namely polyester fiber beads. The hydrogen producing dark fermentative microorganisms were obtained by heat-pretreatment of anaerobic sludge from the acidogenic phase of an anaerobic wastewater treatment plant. Glucose was the sole carbon source and the initial concentration was 15 ± 1 g/L throughout the continuous feeding. UPBR was operated under the thermophilic condition at T = 48 ± 2 °C and at varying HRTs between 2 h and 6 h. The hydrogen productivity of continuously operated UPBR increased with increasing HRT. Hydrogen production volume varied between 4331 and 6624 ml/d, volumetric hydrogen production rates (VHPR) were obtained as 3.09–4.73 L H 2 /L day, and hydrogen production yields (HY) were 0.49 mol/mol glucose-0.89 mol/mol glucose depending on HRT. Maximum daily hydrogen volume (6624 ml/d), the yield (0.89 mol/mol glucose) and VHPR (4.73 L H 2 /L day) were obtained at HRT = 6 h. The production rate and the yield decreased with increasing organic loading rate due to substrate inhibition. Image 1 • UPBR was operated continuously at HRTs between 2 h and 6 h. • Polyester fiber beads were used for immobilization of heat pretreated sludge. • Maximum H 2 yield of 0.89 mol/mol glucose was attained at HRT = 6 h. • Maximum volumetric H 2 production rate of 4.73 L H 2 /L day was obtained at HRT = 6 h. • H 2 content was stable around 60% at all HRT. [ABSTRACT FROM AUTHOR]

By taking advantage of the high catalytic activity and high turnover frequency (TOF) of heterogeneous metal nanoparticle catalysts, continuous-flow systems, in which introduced reactants are converted into the desired product in high yield, can be realized. These continuous-flow reactors possess high compatibility with sequential continuous-flow systems, which enable multistep flow synthesis of biologically active compounds such as active pharmaceutical ingredients (APIs) and natural products. [ABSTRACT FROM AUTHOR]

• Thermochemical energy storage using iron–manganese oxide granular particles. • High-temperature heat transfer study in a lab-scale packed-bed reactor. • Two-dimensional, transient, pseudo-homogeneous modelling. • Effective heat transfer parameters determination. Heat transfer is studied in a lab-scale tubular reactor packed with spherical 0.5–1 mm iron–manganese oxide particles with an Fe/Mn molar ratio of 2:1. A two-dimensional transient heat transfer model considering conduction, convection and radiation heat transfer is developed to simulate the temperature profile in the reactor. The effective thermal conductivity of the packed bed as well as the wall heat transfer coefficient are determined based on the experimental data and a steady-state model. The validity of calculated effective parameters is checked by employing the parameters in a transient model and comparing the predicted temperature profile with transient experimental data and by comparison with existing correlations found in the literature. [ABSTRACT FROM AUTHOR]

Biodegradation of phenolic compounds in wastewater can be effectively carried out in packed bed reactors (PBRs) employing immobilized microorganisms. A low-cost, reusable immobilization matrix in PBR can provide economic advantages in large scale removal of high concentration phenol. In this study, we evaluated the efficiency and reusability of sugarcane bagasse (SCB) as a low-cost immobilization support for high strength phenol removal in recirculating upflow PBR. An isolated yeast Candida tropicalis PHB5 was immobilized onto the SCB support and packed into the reactor to assess phenol biodegradation at various influent flow rates. Scanning electron microscopy exhibited substantial cell attachment within the pith and onto the fibrous strand surface of the SCB support. The PBR showed 97% removal efficiency at the initial phenol concentration of 2400 mg L−1 and 4 mL min−1 flow rate within 54 h. Biodegradation kinetic studies revealed that the phenol biodegradation rate and biodegradation rate constant were dependent on the influent flow rate. A relatively higher rate of biodegradation (64.20 mg g−1 h−1) was found at a flow rate of 8 mL min−1, indicating rapid phenol removal in the PBR. Up to six successive batches (phenol removal >94%) were successfully applied in the PBR using an initial phenol concentration of 400–2400 mg L−1 at a flow rate of 4 mL min−1 indicating the reusability of the PBR system. The SCB-immobilized C. tropicalis could be employed as a cost-effective packing material for removal of high strength phenolic compounds in real scale PBR. Image 1 • Sugarcane bagasse was used as an immobilization support and packing material for PBR. • The PBR with immobilized C. tropicalis showed 97% phenol removal at 2400 mg L−1. • A maximum phenol biodegradation rate of 64 mg g−1 h−1 was achieved. • Repeated use of the packed bed reactor was possible for up to six batches. [ABSTRACT FROM AUTHOR]

Abstract Increasing energy demands coupled with decreasing fossil fuel resources create an urgent need to switch over bio-based fuel, such as biodiesel. In a newly designed reactor, the production of biodiesel was conducted with soybean oil (SBO) in solvent-free system through transesterification by immobilized Burkholderia cepacia lipase under the influence of ultrasonic emulsification. Effects of operational parameters viz. methanol-to-oil molar ratio, water concentration, immobilized enzyme concentration, and temperature on fatty acid methyl esters (FAME) yield were investigated. Molar ratio and enzyme concentration showed a significant linear correlation with biodiesel yield (r = − 0.8 and 0.6; respectively). Linear regression analysis of both parameters later revealed a significant prediction ability for biodiesel with a yield of 78.8 and 31.7%, respectively. FAME yield was 30% at 7 h in the pretreatment reactor. Without ultrasonic emulsification, the yield was significantly enhanced to 64% for the same reaction time in the packed-bed reactor. However, the reaction time was further reduced significantly under the influence of ultrasonic emulsification coupled with immobilized lipase as a catalyst and resulted into higher biodiesel yield of 68.6% at 3 h. Clearly, ultrasonic emulsification-assisted immobilized lipase catalysis of SBO might be a potential alternative route to conventional methods of biodiesel production. Graphical abstract Image 1 Highlights • Design a novel biodiesel (BD) reactor in a continuous flow through enzymatic catalysis in immobilized media. • Under 0.5 ml min−1 of continuous flow, the BD yield varied from 26.8% to 28.9% in 11 h. • The pore size of the permeable membrane (38 μm), allowing a higher contact between the fluids and the lipase. • Combination of pretreatment and continuous flow reaction have a promising future for BD production. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A. oryzae β-gal immobilized on glyoxyl agarose was tested in CPBR for the first time. • Highest Y Lu obtained was 0.6 g·g−1 for continuous operation in a packed bed reactor. • Flow, substrate molar ratio and enzyme/inert support affected CPBR performance. • Lactulose synthesis in CPBR is a sound alternative to conventional batch synthesis. Abstract Lactulose synthesis from fructose and lactose in continuous packed-bed reactor operation with glyoxyl-agarose immobilized Aspergillus oryzae β-galactosidase is reported for the first time. Alternative strategies to conventional batch synthesis have been scarcely explored for lactulose synthesis. The effect of flow rate, substrates ratio and biocatalyst-inert packing material mass ratio (M B /M IM) were studied on reactor performance. Increase in any of these variables produced an increase in lactulose yield (Y Lu) being higher than obtained in batch synthesis at comparable conditions. Maximum Y Lu of 0.6 g·g−1 was obtained at 50 °C, pH 4.5, 50% w/w total sugars, 15 mL·min−1, fructose/lactose molar ratio of 12 and M B /M IM of 1/8 g·g−1; at such conditions yield of transgalactosylated oligosaccharides (Y TOS) was 0.16 g·g−1, selectivity (lactulose/TOS molar ratio) was 5.4 and lactose conversion (X Lactose) was 28%. Reactor operation with recycle had no significant effect on yield, producing only some decrease in productivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A continuous packed-bed reactor was applied for 5-HMF synthesis. • High yield of 91.67% and selectivity toward 5-HMF of 99.76% were simultaneously obtained. • Effects of reaction conditions on the synthesis of 5-HMF were investigated. Abstract A continuous packed-bed reactor was applied for the synthesis of 5-HMF via dehydration of fructose. Cation exchange rasin functionalized with sulfonic acid groups; -HSO 3 was used as catalyst. 1-methyl-2-pyrrolidinone (NMP) was used as aqueous solvent to partially substitute water. A biphasic system with methyl isobutyl ketone (MIBK) as organic solvent was applied to enhance the transfer of 5-HMF from aqueous phase. Effects of reaction temperature (90–120 °C), residence time (10–60 min), water content in the aqueous phase (30–100 %wt.), and organic-to-aqueous ratio (1:1–4:1) on the conversion of fructose, %yield and selectivity of 5-HMF, and extraction ratio were investigated. High yield of 5-HMF was obtained with increasing reaction temperature or reaction time. Adding NMP enhanced the fructose conversion and selectivity toward 5-HMF to 91.67% and 99.76% at 120 °C, residence time of 30 min, NMP-to-water ratio of 7:3, and organic-to-aqueous ratio of 4:1, while the extraction ratio was 81.83%. [ABSTRACT FROM AUTHOR]

A continuous flow procedure for the gem-dichlorocyclopropanation of alkenes has been developed. The method is based on the generation of dichlorocarbene utilizing the classical biphasic aqueous sodium hydroxide/chloroform system. This reaction typically requires vigorous stirring for several hours in batch for completion. Tarry materials precipitate due to partial polymerization of dichlorocarbene and the process is difficult to scale. To overcome these problems and achieve very efficient mixing during the flow process a column reactor packed with PTFE beads as inert filling material has been used. PTFE beads have been found to be the optimal material to obtain fine dispersions of the aqueous phase in the organic solution. By heating the packed-bed reactor at 80 °C excellent conversions have been achieved after a residence time of only 4 min. The process has been applied for the synthesis of Ciprofibrate, a dichlorocyclopropane-containing drug used as treatment for several diseases associated with high lipid content in blood. [ABSTRACT FROM AUTHOR]