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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]

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]

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]

[Display omitted] • A lower gas–liquid ratio at increasing WHSV reduces temperature differences. • Liquid-solid mass transfer limitation occurs in porous catalysts. • The decreased evaporation results in a smaller temperature difference. • The effect of pressure on chemical equilibrium is more critical than temperature. The dehydrogenation of dodecahydro- N -ethylcarbazole (H12-NEC) generates enormous gas accompanied by intense heat absorption, affecting heat and mass transfer in porous catalysts. A packed-bed reactor equipped with a temperature measurement device was designed to investigate the continuous flow dehydrogenation of H12-NEC. The effects of weight hourly space velocity (WHSV), reaction temperature, catalyst particle size, and pressure were evaluated. The results reveal that the volume flow rate of hydrogen will increase with the increase of WHSV. And the reduction of gas–liquid ratio and catalyst particle size facilitates heat transfer causing a more uniform axial temperature distribution within the reactor. As the temperature rises, the hydrogen yield increases along with more by-products. 456 K and 2 mm of catalyst particle size are determined to be the optimal reaction conditions in the study, achieving the hydrogen production rate of 9.61 mol H 2 · g Pd -1 · h -1. With pressure increasing, the hydrogen yield gradually decreases, but the decreased evaporation of H12-NEC results in a smaller temperature difference between the reactor and heating wall. A comparison with the thermodynamic equilibrium model reveals that the effect of pressure on chemical equilibrium may be more significant than the temperature. [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]

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]

• 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]

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]

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]

• 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]

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]

[Display omitted] • BT substitute was prepared in a pilot-scale PBR using interesterified plant oils. • The physical properties of BT substitute have been improved compared to BT. • The volatile profiles of BT substitute-based hotpots has no significant difference with BT ones. Edible beef tallow (BT) has been widely used in Sichuan hotpot due to its unique flavor and texture. However, BT should not be consumed in excess caused by its trans -fatty acids and cholesterol issues. In this study, a BT substitute was prepared after enzymatic interesterification in a pilot-scale packed-bed reactor using soybean oil and fully hydrogenated palm oil (4:3, w/w) as feedstock. The products were characterized against BT in terms of fatty acid/triacylglycerol compositions, solid fat content, polymorphism, and melting/crystallization behaviors to select the most promising BT substitute. The optimal flow rate was 120 mL/min. Changes in volatile compounds during stir-frying and simmering were also investigated for Sichuan hotpots made with these two oils. The volatile compounds of BT substitute were similar to that of natural BT. The findings will contribute to expanding the base oil categories of Sichuan hotpot oils. [ABSTRACT FROM AUTHOR]

DBD plasma reactors are of great interest for environmental and energy applications, such as CO 2 conversion, but they suffer from limited conversion and especially energy efficiency. The introduction of packing materials has been a popular subject of investigation in order to increase the reactor performance. Reducing the discharge gap of the reactor below one millimetre can enhance the plasma performance as well. In this work, we combine both effects and use a packed-bed DBD micro plasma reactor to investigate the influence of gap size reduction, in combination with a packing material, on the conversion and efficiency of CO 2 dissociation. Packing materials used in this work were SiO 2 , ZrO 2 , and Al 2 O 3 spheres as well as glass wool. The results are compared to a regular size reactor as a benchmark. Reducing the discharge gap can greatly increase the CO 2 conversion, although at a lower energy efficiency. Adding a packing material further increases the conversion when keeping a constant residence time, but is greatly dependent on the material composition, gap and sphere size used. Maximum conversions of 50–55% are obtained for very long residence times (30 s and higher) in an empty reactor or with certain packing material combinations, suggesting a balance in CO 2 dissociation and recombination reactions. The maximum energy efficiency achieved is 4.3%, but this is for the regular sized reactor at a short residence time (7.5 s). Electrical characterization is performed to reveal some trends in the electrical behaviour of the plasma upon reduction of the discharge gap and addition of a packing material. [ABSTRACT FROM AUTHOR]

The conversion of whey permeates to galacto-oligosaccharides (GOS) was studied by the enzymatic action of β-galactosidase from Aspergillus oryzae in a continuous flow packed-bed reactor. A novel method of enzyme immobilization involving covalent immobilization of β-galactosidase on 3-aminopropyl triethoxysilane(3-APTES)-modified glass beads was developed by the cross-linking method. The pH and temperature dependence of the enzymatic efficiency of the glass bead-immobilized enzyme was compared with that of the free enzyme. Increased pH and thermal stabilities were observed for the immobilized enzyme versus the free enzyme. The reusability of the enzyme immobilized packed-bed reactor was studied and only about 4.6% of GOS yield was lost after eight reuses. Repeated cycle reactions were also carried out to improve the formation of GOS. The results showed that the GOS formation increased and a maximum GOS yield of 39.3% with 56.4% lactose conversion was obtained after the 2nd cycle of passing. [ABSTRACT FROM AUTHOR]

A packed‐bed reactor with oxone has been employed for selective oxidations of sulfur compounds. Various sulfides containing different functional groups are efficiently oxidized to the corresponding sulfoxides without formation of sulfones or other side products. [ABSTRACT FROM AUTHOR]

Water-based adsorption thermal battery (ATB) could provide huge possibility in widespread applications; especially for space heating, leading to appreciable energy saving and low-grade heat energy utilization. A proof-of-concept prototype based on composite adsorbents has been constructed to investigate the thermal performances of a packed-bed ATB. A possible strategy of tunning airflow rate for performance regulation is proposed and studied to realize stable thermal output. Additional experimental results indicated that the output temperature and heating power can be synchronously stabilized through progressive tunability of loop airflow rate in the loop-cycle ATB system. The output RH spans 40–60% along the effective discharging process, enabling a controllable humidity management in the application of direct space heating considering human thermal comfort. A three-dimensional computational model for predicting the overall thermal output performances of a packed-bed adsorption thermal battery is further developed and established. The simulation results reveal that an effective heating time of 8.6 h with a discharging threshold temperature of 24 °C, and an average power density of 19.3 kW m−3 can be achieved with a maximum heat discharging efficiency of 63.4%. It is, therefore, apparent that the ATB is capable of achieving stable thermal outputs for space heating applications. • An experimental and numerical parametric study analysis for the packed-bed adsorption thermal battery is conducted. • A strategy of tunning airflow rate for stable output performance is proposed and developed for adsorption thermal battery. • The proposed modelling and optimization method can be employed to analyze and predict overall thermal output performances. • Different combinations of open-cycle and loop-cycle modes in adsorption thermal battery can meet various heating demands. [ABSTRACT FROM AUTHOR]

Thermo-catalytic hydrogenation of CO 2 into synthetic CH 4 via Sabatier reaction is an attractive route to reduce fossil fuels consumption and to limit greenhouse gas emissions, while potentially providing revenue. Hydrogen required for the reaction can be generated by water electrolysis using renewable or low carbon footprint electricity. With respect to CO 2 methanation, a number of technological challenges have to be resolved in order to make this technology economically viable. The highly exothermic nature of the Sabatier reaction makes heat removal a challenging task. Another major problem is catalyst deactivation by coking caused by CH 4 cracking at elevated temperatures. Maximizing CH 4 production over extended periods of operation will require highly efficient heat removal to facilitate CH 4 production, while minimizing catalyst deactivation. In this study, a heat-exchanger type, molten salt-cooled packed bed reactor is analyzed using a transient mathematical model. The model considers inter-compartment heat exchange and catalyst deactivation by coking, assuming the use of a Ni/Al 2 O 3 catalyst. The reactor performance was investigated in terms of CO 2 conversion and CH 4 yield for the case of the feed containing CO 2 and H 2 , and for the case of the reactor fed with biogas (40% CO 2 and 60% CH 4 ) and H 2 . The model predicts that, though the catalyst deactivation leads to a substantial decline in the reactor performance, CH 4 yields and CO 2 conversions over 80% are achievable after 10,000 h of operation. [ABSTRACT FROM AUTHOR]

The anaerobic removal of nitrates was studied in a continuous up-flow stirred packed-bed reactor (USPBR) containing biological sludge carbonaceous material (BSCM). The carbonaceous material (CM), obtained from exhausted sludge, was used as support to grow the biofilm and solid electron mediator for nitrate reduction in the bioreactor. In a continuous USPBR-BSCM system feed with treated synthetic wastewaters, nitrate removal efficiency was 99% at very short space times (τ) 2 min/hydraulic residence times (HRT) 6 min. By comparing these results with the hydraulic residence times applied in other classical denitrification technologies, it seems that USPBR-BSCM requires the shortest times to achieve almost complete nitrate removal. In addition, a high denitrification rate of 3.67 · 10 −3 mmolNO 3− min −1 g −1 was observed in the USPBR-BSCM, whilst in the USPBR-biological activated carbon (BAC) it was 2.04 · 10 −3 mmolNO 3− min −1 g −1 . The kinetic analysis of the systems showed a good fit with the Michaelis–Menten model and the kinetic parameters estimated were k 1 = 3.37 mmol L −1 min −1 , k 2 = 0.58 mmol L −1 for USPBR-BSCM and k 1 = 2.50 mmol L −1 min −1 , k 2 = 0.27 mmol L −1 for USPBR-BAC. Results indicate that SCM is a potentially low cost catalyst and effectively competes with commercial ones; USPBR-BSCM is an inexpensive and advantageous process for nitrate removal and also an effective system for denitrification. [ABSTRACT FROM AUTHOR]

This study reports the immobilization of a β -CGTase on glutaraldehyde pre-activated silica and its use to production of cyclodextrins in batch and continuous reactions. We were able to modulate the cyclodextrin production ( α-, β- and γ- CD) by immobilization and changing the reaction conditions. In batch reactions, the immobilized enzyme reached to maximum productions of 4.9 mg mL −1 of α-CD, 3.6 mg mL −1 of β -CD and 3.5 mg mL −1 of γ -CD at different conditions of temperature, pH and reaction time. In continuous reactor, varying the residence time and pH it was possible to produce at pH 4.0 and 141 min of residence time preferentially γ -CD (0.75 and 3.36 mg mL −1 of α- and γ -CD, respectively), or at pH 8.0 and 4.81 min α- and β -CDs (3.44 and 3.51 mg mL −1 ). [ABSTRACT FROM AUTHOR]

Packed-bed bioreactors (PBRs) have been recognized as a breakthrough technology in industrial wastewater treatment plants due to high removal efficiency and low investment and operating cost. A coupled computational fluid dynamic (CFD) model, combining the fluid dynamics with biochemical reactions was developed to simulate the dynamic behavior of formaldehyde (FA) biodegradation by Ralstonia eutropha in an immobilized cell bioreactor with disk-shaped Kissiris pieces operating in batch-recycling and continuous mode. The multiphase CFD model was investigated to promote the design, optimization and scale-up of the existent environmental technologies on the decontamination of aqueous streams. The Eulerian CFD model was developed to evaluate the effect of different inlet substrate concentrations (1.67–20 mol/m 3 of FA) and feed flow rates (6–60.3 mL/min) on the treatment efficiency under unsteady-state condition by visualizing concentration profiles for FA depletion. To validate the CFD model effectively, the theoretical calculations were compared against experimental biodegradation data reported in the literature and the time-dependent simulation results illustrated a satisfactory agreement with the experimental data. The results clearly demonstrated that the bioreactor operating in batch-recycling mode was more efficient in means of pollutant elimination while increasing the feed flow rate and inlet FA concentration had reverse effect on FA removal efficiency of the bioreactor. The Eulerian computations have shown promising results on how fluid dynamics can be correlated with biochemical reaction model (Luong inhibition model) and reasonably predict the formaldehyde concentration variations along the bioreactor. [ABSTRACT FROM AUTHOR]

The application of microfluidics in organic chemistry is a valuable tool to access new synthesis pathways and to break limitations set by traditional batch chemistry. In the past, the majority of research focused on solving problems associated with individual reactions. It is necessary to advance the field by incorporating flow chemistry in longer multistep syntheses to open more direct paths towards complicated compounds. Several strategies were developed to meet the demands of a four-step synthesis, which includes biphasic nitrations, gaseous substrates, and very fast reactions on multifunctional molecules. A unique micro flow setup was applied in each reaction to meet its specific requirements. [ABSTRACT FROM AUTHOR]

Plasma reactions offer an attractive alternative route for the synthesis of a variety of valuable chemical compounds. Here we investigate the parameters that determine the efficiency of ammonia synthesis in a ferroelectric packed bed dielectric barrier discharge (DBD) reactor. The effects of varying the operating frequency, the size of the ferroelectric pellets and the inter-electrode distance have been systematically studied. Under optimised conditions nitrogen conversions in excess of 7% were achieved, higher than those previously obtained using DBD reactors. These findings are discussed with respect to variations in the electrical characteristics of the reactor under operating conditions and in the light of emission spectra obtained as a function of reactant flow rates. These encouraging results signpost future developments that could very substantially improve the efficiency of ammonia synthesis by means of DBD technology. [ABSTRACT FROM AUTHOR]

The goal of this research was to investigate the using of a packed-microchannel reactor to continuously synthesize biodiesel in a heterogeneous catalyst system. Calcium oxide (CaO) was used as a catalyst and was activated with methanol to enhance the catalytic performance for the transesterification reaction of palm oil. The synthesized activated CaO was characterized and confirmed by using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Hammett indicator and field emission scanning electron microscope (FE-SEM) techniques. The results indicated that the catalyst with higher surface area and total basicity was provided after activation and showed the higher catalytic activity compared to that of as-received CaO. The main important factors affecting the biodiesel synthesis were investigated and the optimal reaction conditions based on the purity of biodiesel were also determined. Complete reaction with the purity of biodiesel of 99% was achieved despite the short residence time used in this research. The optimal reaction conditions within the investigated parameter region were 65 °C, methanol-to-oil molar ratio of 24:1, and residence time of 8.9 min. The catalyst sustained high %FAME over 24 h of continuous operation. Furthermore, high fuel quality and superior productivity performance could be achieved via the packed-microchannel reactor. [ABSTRACT FROM AUTHOR]

The enzymatic route for biodiesel production is environmentally attractive, but costs need to be reduced and reaction times shortened. Costs can be reduced by producing lipases by solid-state fermentation and using the fermented solids directly to catalyze the ethyl-esterification of fatty acids in solvent-free media. However, the esterification studies done to date with fermented solids have involved 12 g or less of fermented solids and reaction times greater than 30 h. The aim of the current work was therefore to increase the scale of the process by an order of magnitude, while also decreasing the reaction time, using bi-distilled olein as the source of fatty acids. The best result was obtained with a molar ratio of ethanol to fatty acids of 1.5:1, in a process in which 245 g of ethanol and 1000 g of olein were circulated in a closed-loop system through a column containing 120 g of dry fermented solids. A two-compartment reservoir was used, with the water in the outflow of the column being decanted in the first compartment. The organic phase that passed to the second compartment was agitated and fed back to the column. This system gave 88% conversion in 24 h. This system was used in 6 successive 48-h batches with the same dry fermented solids, in which a total of 4.6 kg of ester was produced. These are promising results that lay the basis for further scale-up studies. [ABSTRACT FROM AUTHOR]

• A CFD-based method for optimizing the shape of a 2D fixed-bed reactor is presented. • Multi-objective optimization is used to estimate the Pareto front of optimal shapes. • A continuous adjoint method is developed and implemented within OpenFOAM CFD package. • Multi-attribute utility theory decision-making aid method allowed to select a shape. • The best shape is built using a 3D printing technique (stratoconception). This paper presents the development of a geometric shape optimization methodology based on the so-called "Hadamard boundary variation" method for performing very general domain deformations, and the related concept of domain differentiation. The resulting method is used to determine the optimal configuration of a two-dimensional packed-bed reactor that simultaneously optimizes its conversion rate and fluid energy dissipation, and where a homogeneous first-order reaction or a catalytic surface reaction takes place. The considered multi-objective optimization problem is subjected to four constraints: the process model constraints consisting of the Navier–Stokes, continuity and mass balance equations, an iso-volume and two manufacturing constraints. The approach to solve the problem is based on the linear scalarization method which converts the multi-objective problem into a single objective problem. The adjoint system method is used to compute the gradient of the performance indices and constraints. Since the indices are conflicting, the solution of the problem is a set of solutions, called Pareto front. Each optimal solution is evaluated using multi-attribute utility theory (MAUT) to determine the best optimal shape of the reactor. Finally, the resulting shape is fabricated using a 3D printing technique and will be experimentally validated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel strategy accommodates the decreasing CaO activity during operation in fixed bed. • A suitable Cu/Ca ratio calcines well-defined portions of CaCO 3 in each cycle. • Controlled CaCO 3 calcination allows secure operation at temperatures bellow 900 °C. • This strategy can be used to produce separately H 2 and CO 2 from blast furnace gas. • A dynamic reactor model describes the evolution of the process during multiple cycles. The Ca-Cu looping process is a promising CO 2 capture technology designed to produce H 2 and power from a fuel gas. The use of inexpensive and widely available limestone would facilitate the scale up of this technology. This work proposes a novel strategy for packed-bed Ca-Cu looping processes consisting of loading the sufficient amount of CuO to calcine only a well-defined fraction of CaCO 3 in every cycle during the transient period until the limestone reaches a residual solid conversion of 0.06 (typically after 150–200 cycles). In this way, the excess of CaCO 3 in the bed ensures temperatures below 900 °C during operation. The feasibility of this strategy is simulated for the conversion of blast furnace gas (BFG) into a H2-rich product (35 vol%) diluted in N2 via the Ca-Cu looping process at 2 bar and temperatures between 600 and 850 °C, while a separated CO 2 rich gas (55 vol% CO 2 in N 2) is obtained. [ABSTRACT FROM AUTHOR]

• Mandelic acid enantiomers are produced in a modular microreactor-microseparator. • Modular system operates in a fully continuous flow regime. • Immobilized lipase preferentially synthesizes (R)-(−)-mandelic acid within minutes. • Enantiomers are separated in a membrane module with inserted dialysis membrane. • Electric field separates electrically charged enantiomers and uncharged substrate. Mandelic acid enantiomers are key precursors in the synthesis of valuable chiral products. However, separating enantiomers in reasonable amounts is a challenging task despite advances in chiral chromatography and other discontinuous and expensive techniques. To tackle these problems, we designed and tested a modular microfluidic system working in a fully continuous flow regime. The system consists of two modules, namely (i) a packed-bed microreactor (PBR) with immobilized enzyme lipase and (ii) a membrane microseparator driven by an imposed electric field. The immobilized catalyst converts a racemic substrate, methyl mandelate, into mandelic acid enantiomers. The enzyme preferentially synthesizes (R)-(−)-mandelic acid within minutes. The product stream from PBR is fed into a membrane microseparator operated in a counter-current regime. An inserted dialysis membrane and an orthogonally applied electric field completely separate the electrically charged enantiomers from their mixture with unreacted and uncharged methyl mandelate within 1.5 min. Under improved reaction and separation conditions, approximately 1 g of (R)-(−)-mandelic acid are produced per day with almost 60 % enantiomeric excess. Moreover, the productivity of this system is easily scalable without compromising its excellent reaction-transport characteristics. [ABSTRACT FROM AUTHOR]

• A monolithic catalyst structure is designed using the density-based topology optimisation method. • The effects of initial guesses, the energy dissipation constraint, and the Peclet number on the design are investigated. • In comparison to a reference honeycomb geometry, the 3D optimised catalyst shows quantitative improvements in terms of pressure drop and conversion. This research investigates the application of topology optimisation to the design of monolithic catalysts for packed-bed reactors with endothermic reactions. A reactor model has been developed based on the main assumptions of laminar flow and a first-order reaction. The model includes a catalytic reaction whose rate is determined by a proposed Arrhenius equation along with mass transfer limitations. Using the density-based method, the optimisation problem is formulated as a catalyst distribution problem. The catalyst volume fraction of elements in the discretised design domain determines the geometry of the monolithic structure and consequently the momentum, heat, and mass transfer characteristics of the reactor. By a combination of interpolation functions, continuous material properties and a sufficient penalisation for the intermediate fluid volume fraction values are derived. The Globally Convergent Method of Moving Asymptotes (GCMMA) was employed to solve the optimisation problem. The effects of initial guesses, the energy dissipation constraint, and the Peclet number on the design are investigated in a 2D framework. Then through a 3D optimisation, a complex structure with enhanced mass transfer, thermal, and hydraulic behaviour is developed. Compared to a reference honeycomb geometry with the same catalyst volume fraction, the resulting 3D optimised geometry shows quantitative improvements in terms of the conversion and pressure drop. [ABSTRACT FROM AUTHOR]

A simultaneous synthesis of biodiesel, as fatty acid methyl esters, and monoacylglycerols catalysed by the recombinantRhizopus oryzaelipase immobilized by adsorption on Relizyme OD/403M is presented. The use of this 1(3)-positional specific lipase prevents the formation of glycerol as a by-product, thus avoiding its drawbacks. The synthesis was carried out in a solvent-free system and it has been studied in two different reactor systems: stirred tank and packed-bed reactor. Stirred tank reactor presented a high-initial reaction rate and achieved a 33.6% yield, which corresponds to a value of 50.4% of the maximum yield that can be achieved with a 1(3)-positional specific lipase. In packed-bed reactor there was a smaller initial reaction rate, but it was achieved a 49.1% yield, which corresponds to a 73.6% of the maximum yield. When a second batch is performed, the yield decreased only 4% when packed-bed reactor is employed whereas a drastic decrease is observed in a stirred tank operation. Therefore, packed-bed reactor showed a best performance and minor damage to the biocatalyst. [ABSTRACT FROM PUBLISHER]

Chitosan beads from a microbial source, i.e. Aspergillus niger (An), were produced by precipitation method for the first time and compared with supports prepared from an animal source, i.e. shellfish derived chitosan with three different molecular weights (low (LMW), medium (MMW) and high (HMW)). The produced beads were used as enzyme carriers to be applied in a continuous packed-bed reactor (PBR) for white wine protein stabilization. For this purpose, the beads were crosslinked with glutaraldehyde (GDH) and stem bromelain was immobilized on the carrier surface as a model enzyme, following two different procedures (i.e., crosslinking with glutaraldehyde (GDH) and direct linkage (DL)). Drop-like beads with an average diameter of 3.0–3.5 mm and a moisture content of 86–94% were obtained. The morphology of the produced beads in dried state, in terms of shape and surface, was studied by means of a scanning electron microscope (SEM), evidencing the obtainment of nearly spherical or oval particles. The efficacy of the crosslinking procedure and of bromelain immobilization was demonstrated by means of SEM investigation and infrared spectroscopy (FT-IR) analysis, revealing a rougher surface. Various initial protein concentrations ranging between 0.45 and 18.00 mg BSAeq mL −1 were tested in order to identify the optimal amount and to evaluate the influence of the initial concentration on the total protein loading. Stem bromelain proved to be more active when immobilized by DL on An beads and was efficient in reducing white wine hazing potential continuously, as verified with a laboratory bench-scale PBR. [ABSTRACT FROM AUTHOR]