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The mineral carbonation process was proposed for effective CO2 capture and utilization from flue gas streams, such as those emitted by coal-fired power plants. In the present work, an alternative technology using sodium hydroxide (NaOH) solution as an absorbent for capturing CO2 and converting it into value-added materials while mitigating emissions was provided. This research examined the use of a packed bed reactor and a bubble column reactor for CO2 absorption and carbonation of NaOH solution to produce sodium bicarbonate (NaHCO3), offering a more environmentally friendly production process compared to traditional methods. The influence of significant operating parameters, namely pH value, gas flow rate, and absorbent flow rate, on CO2 capture in a bubble column reactor was experimentally explored using NaOH solution. The formation of sodium bicarbonate during the carbonation experiment was confirmed by X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The experimental results show a CO2 removal efficiency exceeding 95% and a NaHCO3 purity above 94% when utilizing a bubble column reactor. [ABSTRACT FROM AUTHOR]

Brazil has one of the greatest biodiversities on the planet, where various crops play a strategic role in the country's economy. Among the highly appreciated biomasses is babassu, whose oil extraction generates residual babassu mesocarp (BM), which still needs new strategies for valorization. This work aimed to use BM as a support for the immobilization of Thermomyces lanuginosus lipase (TLL) in an 8.83 mL packed‐bed reactor, followed by its application as a biocatalyst for the synthesis of hexyl laurate in an integrated process. Initially, the percolation of a solution containing 5 mg of TLL at 25 °C and flows ranging from 1.767 to 0.074 mL min−1 was investigated, where at the lowest flow rate tested (residence time of 2 h), it was possible to obtain an immobilized derivative with hydrolytic activity of 504.7 U g−1 and 31.7 % of recovered activity. Subsequent studies of treatment with n‐hexane, as well as the effect of temperature on the immobilization process, were able to improve the activities of the final biocatalyst BM‐TLLF, achieving a final hydrolysis activity of 7023 U g−1 and esterification activity of 430 U ⋅ g−1 against 142 U g−1 and 113.5 U g−1 respectively presented by the commercial TLIM biocatalyst. Desorption studies showed that the TL IM has 18 mg of protein per gram of support, compared to 4.92 mg presented by BM‐TLL. Both biocatalysts were applied to synthesize hexyl laurate, achieving 98 % conversion at 40 °C within 2 h. Notably, BM‐TLLF displayed exceptional recyclability, maintaining catalytic efficiency over 12 cycles. This reflects a productivity of 180 mg of product ⋅ h−1 U−1 of the enzyme, surpassing 46 mg h−1 U−1 obtained for TLIM. These results demonstrate the efficacy of continuous flow technology in creating a competitive and integrated process offering an exciting alternative for the valorization of residual lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Methanol synthesis is carried out in a catalytic, packed bed reactor, where the shape and size of catalyst play a critical role in dictating overall reactor performance. In the current study, the effect of five different catalyst shapes including cylindrical, ring, trilobe, wagon wheel, and spherical on the reactor performance was investigated by conducting particle‐scale computational fluid dynamics (CFD) simulations. The predictions of pressure drop, velocity, temperature, reactant distribution and product yield were analyzed. When the performance of the simulated shapes was compared at the same tube Reynolds number of 50,000, internally contoured shapes (wagon wheel and ring) resulted in 40% higher pressure drops due to the tortuous flow path. However, the shape with internal void provided access for the reactant to reach the internal part of catalyst, resulting in higher yield produced per volume of catalyst. The wagon wheel shape produced 15% and 5% more yield per volume against the cylindrical shape and trilobe, respectively. The performance of the wagon wheel can be attributed to the lower diffusion limitation due to higher surface area available for reactant to penetrate the internal part of the catalyst. [ABSTRACT FROM AUTHOR]

In light of the growing demand for novel biocatalysts and enzyme production methods, this study aimed to evaluate the potential of Aspergillus tubingensis for producing lipase under submerged culture investigating the influence of culture time and inducer treatment. Moreover, this study also investigated conditions for the immobilization of A. tubingensis lipase by physical adsorption on styrene–divinylbenzene beads (Diaion HP-20), for these conditions to be applied to an alternative immobilization system with a packed-bed reactor. Furthermore, A. tubingensis lipase and its immobilized derivative were characterized in terms of their optimal ranges of pH and temperature. A. tubingensis was shown to be a good producer of lipase, obviating the need for inducer addition. The enzyme extract had a hydrolytic activity of 23 U mL−1 and achieved better performance in the pH range of 7.5 to 9.0 and in the temperature range of 20 to 50 °C. The proposed immobilization system was effective, yielding an immobilized derivative with enhanced hydrolytic activity (35 U g−1), optimum activity over a broader pH range (5.6 to 8.4), and increased tolerance to high temperatures (40 to 60 ℃). This research represents a first step toward lipase production from A. tubingensis under a submerged culture and the development of an alternative immobilization system with a packed-bed reactor. The proposed system holds promise for saving time and resources in future industrial applications. [ABSTRACT FROM AUTHOR]

Continuous flow technologies have become increasingly important for biocatalytic processes. In this study, we present the application and modelling of covalently immobilised N-acetylglucosamine 2-epimerase and N-acetylneuraminic acid lyase in packed bed reactors for the synthesis of N-acetylneuraminic acid. The immobilised enzymes were stable under continuous flow process conditions with half-life times of >28 d (epimerase immobilised on hexamethylamino methacrylate HA403/M) or 58 d (lyase immobilised on dimenthylamino methacrylate ECR8309M), suitable for continuous flow applications. Kinetic studies revealed Michaelis–Menten kinetic behaviour for both enzymes. The kinetic parameters and the inhibitions were analysed under continuous flow conditions and were integrated into a process model using Python. The model was validated by varying flow rates, the mass of immobilised enzymes and the reactor dimensions and shows a low error compared to the measured data. An error accuracy of 6% (epimerase) or 9% (lyase) was achieved. The product concentrations of the enzyme cascade at the end of the packed bed reactor can be predicted with an accuracy of 9% for the calculation of a large column (84.5 mL) or of 24% if several small columns (2.5 mL, 0.8 mL) are connected in series. The developed model has proved to be valid and will be used to optimise the process with respect to substrate concentrations, reactor dimensions and flow rate. [ABSTRACT FROM AUTHOR]

Thermochemical storage using salt hydrates presents a promising energy storage method. Ensuring the long-term effectiveness of the system is critical, demanding both chemical and mechanical stability of material for repetitive cycling. Challenges arise from agglomeration and volume variations during discharging and charging, impacting the cyclability of thermochemical materials (TCM). For practical usage, the material is often used in a packed bed containing millimetre-sized grains. A micro-level analysis of changes in a packed bed system, along with a deeper understanding involving quantifying bed characteristics, is crucial. In this study, micro X-ray computed tomography (XCT) is used to compare changes in the packed bed before and after cycling the material. Findings indicate a significant decrease in pore size distribution in the bed after 10 cycles and a decrease in porosity from 41.34 to 19.91% accompanied by an increase in grain size, reducing void space. A comparison of effective thermal conductivity between the uncycled and cycled reactor indicates an increase after cycling. Additionally, the effective thermal conductivity is lower in the axial direction compared to the radial. XCT data from uncycled and cycled experiments are further used to observe percolation paths inside the bed. Furthermore, at a system scale fluid flow profile comparison is presented for uncycled and cycled packed beds. It has been observed that the permeability decreased and the pressure drop increased from 0.31 to 4.88 Pa after cycling. [ABSTRACT FROM AUTHOR]

Abstract Reductive amination by amine dehydrogenases is a green and sustainable process that produces only water as the by-product. In this study, a continuous flow process was designed utilizing a packed bed reactor filled with co-immobilized amine dehydrogenase wh84 and glucose dehydrogenase for the highly efficient biocatalytic synthesis of chiral amino alcohols. The immobilized amine dehydrogenase wh84 exhibited better thermo-, pH and solvent stability with high activity recovery. (S)-2-aminobutan-1-ol was produced in up to 99% conversion and 99% ee in the continuous flow processes, and the space-time yields were up to 124.5 g L-1 d-1. The continuous reactions were also extended to 48 h affording up to 91.8% average conversions. This study showcased the important potential to sustainable production of chiral amino alcohols in continuous flow processes.

Reductive amination by amine dehydrogenases is a green and sustainable process that produces only water as the by-product. In this study, a continuous flow process was designed utilizing a packed bed reactor filled with co-immobilized amine dehydrogenase wh84 and glucose dehydrogenase for the highly efficient biocatalytic synthesis of chiral amino alcohols. The immobilized amine dehydrogenase wh84 exhibited better thermo-, pH and solvent stability with high activity recovery. (S)-2-aminobutan-1-ol was produced in up to 99% conversion and 99% ee in the continuous flow processes, and the space-time yields were up to 124.5 g L-1 d-1. The continuous reactions were also extended to 48 h affording up to 91.8% average conversions. This study showcased the important potential to sustainable production of chiral amino alcohols in continuous flow processes. [ABSTRACT FROM AUTHOR]

The present study contributes to overcoming the serious drawback of the traditional stirred slurry catalytic reactor, namely, the costly and time‐consuming separation of the catalyst particles from the final product using a stationary fixed bed of Raschig rings placed above a rotating impeller. The rate of diffusion‐controlled reactions was measured in terms of the mass transfer coefficient under different conditions of impeller rotation speed, Raschig ring diameter, and bed height. The rate of mass transfer was determined by a technique which involves measuring the rate of diffusion‐controlled dissolution of copper in acidified dichromate. The data were correlated by a dimensionless correlation which can be used to scale up and design the reactor. The reactor performance was measured in terms of the mass transfer coefficient and the energy utilization efficiency. Possible applications of the reactor in conducting diffusion‐controlled reactions were highlighted. [ABSTRACT FROM AUTHOR]

To predict the temperature profile in an ohmic reactor, it is essential to know the thermal and electrical conductivity of the reactor geometry. Those properties can be considered on different modeling scales: On the detailed (resolved) scale, the reactor consists of a packed bed structure, where the properties of each substance are considered. On the effective (continuum) scale, the packed bed is considered as effective medium with composite properties. In this contribution, we consider both scales and compare the results. Based on the detailed description with a resolved microstructure, the bed's effective thermal and electrical conductivity are computed. These properties are compared with analytical formulas. The electrical conductivity is the basis for the electrical field and the current density. Finally, these properties are used to evaluate the ohmic heating of the packed bed exposed to flow and to compute the temperature distribution within the reactor. [ABSTRACT FROM AUTHOR]

Present investigation provides an insight into fluoride uptake by immobilized beads of two fluoride-resistant bacterial species Providencia vermicola (KX926492) (PV) and Staphylococcus lentus (KX941068) (SL) from simulated waste water in packed bed column reactor. Experiments have been carried out to assess the effects of parameters like influent fluoride concentration, feed flow rate and bed height on fluoride removal. The column data were fitted to Adams-Bohart and Yoon-Nelson models to determine the influence on biosorption performance. Different influential parameters were studied such as fluoride concentration (15–25 mg L−1), rate of feed flow (2, 4 and 6 mL min−1) and height of bed (4, 6 and 8 cm). Optimum operating conditions were observed to be: concentration (conc) = 20 mg L−1, influent flow rate = 2 mL min−1 and bed height = 8 cm. A maximal fluoride uptake ability of 32.48 mg g−1 has been achieved under these conditions. The experimental results of the breakthrough curves fit well with the Yoon-Nelson model. Therefore, immobilized beads of PV and SL could serve as potent remediating agents towards water defluoridation in large-scale operations. [ABSTRACT FROM AUTHOR]

Methanol to olefin conversion has captured the attention of the industry as olefins are feed material to many polymer industries. In this work methanol conversion to olefins was investigated over beds of (i) physical mixture of metal oxides with ZSM-5 (PMB) and (ii) metal impregnated over ZSM-5 (MLB). ZSM-5 used in the current study was pre modified by boric acid treatment for modifying catalytic active site composition. Two different metals from alkaline series: calcium and magnesium & from transition metal series: iron and copper were selected. PMB studies were performed on 1:1 (by weight) metal oxides and BZSM-5 whereas for MLB studies, 10 % metal was loaded. Performance studies of the two different bed composition were performed at 500°C, 100 ml/min N2 flow with 1 g catalyst in a fixed bed reactor. 100 % conversion was obtained on MLB studies in presence of Cu, Mg and Fe whereas in PMB studies, 100 % conversion could be obtained over FeO+BZSM-5 bed. The order of olefins yield obtained was in the following order: BZSM-5 > Mg/BZSM-5 > Cu/BZSM-5 > CuO+BZSM-5 > CaO+BZSM-5 > Fe/BZSM-5 > FeO+BZSM-5 > CaO+BZSM-5 > MgO+BZSM-5. It was observed that maximum methane yield was obtained in presence of physical mixture. Gaseous products other than olefins with high composition of C1–C4 hydrocarbons were formed in presence of Mg and Ca whereas the metal impregnated modified-ZSM-5 produced higher content of olefins with Cu loaded catalysts in both bed composition. Metal impregnated catalysts as well as physical mixtures were characterized by BET, FTIR and XRD, FESEM for surface area, topology, crystallinity etc. Spent catalysts were characterized for coke deposition using TGA.

The benzyltoluene- and dibenzyltoluene-based liquid organic hydrogen carrier (LOHC) technology is approaching a level of maturity that enables its large-scale implementation for hydrogen storage and transport applications. To support this progress, our study investigates the continuous dehydrogenation of both LOHC systems in a packed bed tubular reactor equipped with high-resolution temperature measurement. Our experiments cover a wide range of reaction conditions resulting in various degrees of dehydrogenation (DoD). In particular, our study highlights the relevance of LOHC evaporation in the dehydrogenation reactor caused by the large amounts of hydrogen gas formed and consequently the low LOHC partial pressure in the reactor. Evaporation of the LOHC compounds is more pronounced for the benzyltoluene-than for dibenzyltoluene-based system. This leads to a shortening of the residence time in the reactor and less favourable heat transfer properties. Interestingly, these seemingly unfavourable properties of the benzyltoluene-based system are compensated by faster gas phase kinetics and lower convective heat removal from the reactor, resulting in very similar heat consumption values for both systems under continuous operating conditions. • Continuous hydrogen release from LOHC under technically relevant conditions. • Comparative analysis of the systems H12-BT and H18-DBT. • Detailed examination of pressure and temperature dependency of LOHC dehydrogenation. • Balancing of heat consumption including reaction, convection and evaporation. • Hydrogen formation and evaporation significantly affect heat transfer conditions. [ABSTRACT FROM AUTHOR]

The catalytic properties of packed bed reactors filled with Y(OTf)3 immobilised onto functionalised silica have been tested in the Michael addition of indoles to benzylidene malonates under flow conditions, providing improved productivity over the batch conditions, a greater ease of recovery of the final products and a prolonged life of the catalyst. Noteworthy, the same catalytic reactor, after being used for five days, was employed to perform a different reaction, a stereoselective Diels Alder cycloaddition in flow, with a 24 times higher productivity compared to the in‐batch reaction. [ABSTRACT FROM AUTHOR]

Summary: The present study evaluated the production of galactooligosaccharides (GOSs) from lactose in both batch and continuous modes using nano‐immobilised β‐galactosidase. Mesoporous silicon dioxide nanoparticles were used to immobilise β‐galactosidase to enhance the stability and production of GOSs. The change in enzyme‐characteristics was assessed using Fourier‐transform infrared and scanning electron microscope analysis. The nano‐immobilisation increased the enzyme's substrate affinity, but decreased its hydrolytic activity. A significant increase (P < 0.05) in stability was observed across a wide range of temperature (30 °C–70 °C) and pH (5.0–8.0). Both forms of enzymes (free and nano‐immobilised enzymes) followed the zero‐order reaction in all temperatures, while the nano‐immobilised enzyme had the highest activation energy. The free and nano‐immobilised enzymes retained 64.65% and 77.82% of their initial activity after 90 days of storage, respectively. In a batch mode, the nano‐immobilised enzyme produced 2.35 times more GOSs than the free enzyme. The GOSs production remained consistent while the enzyme activity decreased by 12.7% after 5 cycles of operation. The continuous mode of production in a packed bed reactor achieved a GOSs yield of 16.92%. Overall, the nano‐immobilised enzyme showed better GOSs production under batch and continuous mode of operation. [ABSTRACT FROM AUTHOR]

Ideal catalysts with all‐around advantages including high efficiency and selectivity, environment‐benign and good recyclability, etc. have been long‐sought yet challenging. Herein, the stable porous aromatic framework covalently embedded with N‐Hydroxyphthalimide (NHPI) organocatalytic site was constructed to establish an ideal catalytic system. The synthesized PAF‐NHPI catalyst was demonstrated to be metal‐free, highly efficient, selective, recyclable and heterogeneous for the aerobic oxidation of various alcohols, aldehydes, olefins, and hydrosilanes (totally 66 examples). As a proof‐of‐concept, the continuous PAF‐NHPI packed bed reactor achieved persistent conversion of 1‐phenylethanol to acetophenone up to 95 % yield. This work provides the inspiration for developing ideal catalysts in practical production of fine chemicals. [ABSTRACT FROM AUTHOR]

Chemical looping combustion (CLC) offers innovative carbon capture via oxygen carrier (OC) circulation between separate reactors. Circulating fluidized beds facilitate OC transport between fuel and air reactors for reduction and oxidation. By avoiding direct contact between fuel and air, minimal energy is required for CO2 separation. Disadvantages resulting from the conventional circulating fluidized bed system are the additional energy necessary for OC transportation and the challenge to operate at elevated pressure. A novel approach to CLC is proposed by considering a packed bed system with stationary OC particles undergoing periodic reduction and oxidation stages by shifting feed gas streams. The major design benefit lies in the prospect of process operation at high pressure. Finding optimal operating conditions is a mandatory step prior to implementing the process at industrial level. In this work, COMSOL Multiphysics was used for computational fluid dynamics (CFD) modelling in order to simulate the syngas-based CLC process with ilmenite OC in a packed bed reactor configuration. Mass, momentum and heat transfer mechanisms were accounted for to describe the combustion, purge and regeneration stages within a bed of randomly packed spherical OC particles at both macro- and micro-scale dimensions. The scope of the particle-resolved CFD multiscale model with realistic bed morphology was the in-depth analysis of the intraparticle phenomena occurring during the redox reactions, with emphasis on heat transport. Model results agree with published literature and provide additional understanding regarding the process in order to contribute towards the design of a flexible and energy efficient power plant concept. [ABSTRACT FROM AUTHOR]

Esters of trifluoroacetic acid are compounds having important applications in the process industry. Methyl trifluoroacetate (MTFA) is useful as an intermediate in the manufacture of valuable pharmaceutical and agriculture chemicals. This work has investigated transesterification of ethyl trifluoroacetate (ETFA) to MTFA using Amberlyst-15. Evaluation of reaction kinetics was followed by regression to obtain kinetic parameters. Packed bed reactor experiments were performed thereafter to improve the process and to make the process continuous, wherein conversion of 76% was achieved in 5 h under the conditions used. Starting from a mixture of reactants, a complete process to obtain pure MTFA was developed in this work. For this, liquid-liquid extraction, adsorption over molecular sieves followed by distillation was used. [ABSTRACT FROM AUTHOR]

This study demonstrates the characteristics of two model packing configurations: 3D printed (3DP) catalyst monoliths on the one hand, and their conventional counterparts, packed beds of spheres, on the other. Cobalt deposited on alumina is selected as a convenient model system for this work, due to its wide spread use in many catalytic reactions. 3DP constructs were produced from alumina powder impregnated with cobalt nitrate while the alumina spheres were directly impregnated with the same cobalt nitrate precursor. The form of the catalyst, the impregnation process, as well as the thermal history, were found to have a significant effect on the resulting cobalt phases. Probing the catalyst bodies in situ by XRD-CT indicated that the level of dispersion of identified Co phases (Co3O4 reduced to CoO) across the support is maintained under reduction conditions. The packed bed of spheres exhibits a non-uniform distribution of cobalt phases, including a core-shell morphology with an average crystallite size of 10–14 nm across the sphere, while the 3DP monolith exhibits a uniform distribution of cobalt phases with an average crystallite size of 5–12 nm upon reduction from Co3O4 to CoO. Computational Fluid Dynamics (CFD) modelling was carried out to develop digital twins and assess the effect of the geometry of both configurations on the pressure drop and velocity profiles. Finally, the activity of both Cobalt-based catalyst geometries was assessed in terms of their conversion, selectivity and turn over frequencies under model multiphase (selective oxidation) reaction conditions, which showed that the desired 3D printed monolithic geometries can offer distinct advantages to the reactor design.

The study involved the development and modeling of a fixed-bed bioreactor for the removal of urea from wines. The reactor, based on the immobilization of acid urease enzyme, was studied under both stationary and non-stationary conditions. The developed model, including internal and external catalyst particle mass transfer, Michaelis-Menten kinetics, convection and dispersion in the liquid along the reactor axis, was able to produce urea concentration profiles in both the solid and liquid phases under various volumetric flow rates and inlet urea concentrations. The experimental results were in good agreement with the model predictions, the mean relative error between simulated and experimental outlet ammonia concentration ranging from 4.1 % to 16.4 %. Model simulations confirmed that in wines the reaction kinetics is of the pseudo-first order and that internal and external catalyst particle diffusion limitations are negligeable. Simulations of the decrease of urea concentration as a function of space velocity for the reactor under study operating in the continuous mode and for three different wines were obtained confirming that urea removal by immobilized urease in wines is more difficult than in sake. The results obtained form the basis for the designing and scaling up of bioreactors for the treatment of wines. [ABSTRACT FROM AUTHOR]

A packed bed reactor (PBR)‐based chemical looping combustion (CLC), also referred to as unmixed combustion (UMC), was reported as an alternative to fire in the literature. In this process, the oxygen carriers undergo oxidation and reduction reactions in alternate cycles using air and fuel as the reactive gases, respectively. The energy generated in these reactions can radially be transferred for applications like heating air which was successfully demonstrated. The results showed that 85–95% of the generated energy can radially be transferred while maintaining sustained combustion in the bed (at temperatures between 723 and 1173 K). While extending its application for heating liquids like water, it was found in the modeling and simulation study that the existing design resulted in quenching of the bed below 773 K in the oxidation cycle and achieving sustained combustion was not possible for all practical ranges of operating parameters. Hence it was decided to modify the existing system by increasing the volume ratio of the annular bed to the liquid section. Theoretical estimations revealed that increasing this ratio by four times or higher can result in maintaining sustained combustion conditions in the bed while having continuous radial heat transfer to the water flowing in the laminar range. The general guidelines for designing a UMC‐based liquid heating system were then prepared and used to propose a new design for water heating. The modeling and simulation studies for this proposed design also indicated that it is a feasible design. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The current study focuses on a comprehensive review of the pilot scale production of biohydrogen and various factors affecting the design experiments. Biohydrogen is a clean energy carrier that can be used as a potential alternative to fossil fuels. Biohydrogen as a fuel has several advantageous attributes, including; carbon-neutral or carbon-zero nature, easy renewability, eco-efficient productivity (via biological routes), eco-friendly conversion, and the highest energy content among all existing fuels. Pilot-scale production of biohydrogen is limited because it requires a better understanding of the possible interactions involved in the process. In this review, biohydrogen production on various types of reactors such as stirred tank reactors, packed bed reactors, fluidized bed reactors, trickling filter reactors, etc., have been discussed. However, biohydrogen production has been mostly studied on small scale, the most challenging issue concerning large-scale production of biohydrogen is its relatively high cost over fuels from fossil owing to high feedstock and manufacturing costs. Therefore, cost-effective and eco-friendly biohydrogen production technologies should be necessarily developed and continuously improved to make this biofuel more competitive over its counterpart. In comparison with fossil fuels, biohydrogen has a high energy yield and is highly renewable. It can fulfill the future demand as a transport fuel. • Biohydrogen production performances of various reactor configurations. • The pros and cons of each reactor technology for biohydrogen production. • Challenges and perspectives concerning biohydrogen production. • Emerging trends and future scopes of the biohydrogen process. • Socio-economic aspects toward sustainable development. [ABSTRACT FROM AUTHOR]

Decomposition of sulphur trioxide (SO 3) is highly endothermic, catalytic and overall rate-controlling step, in three-step decomposition of sulphuric acid. SO 3 decomposition in Packed Bed Reactor (PBR) involves transport resistances in two (multi) scales; macro-voids and micro-pores together with surface reaction. Objective of the present study is to develop a double porosity (multi-scale) model, DPM for the catalytic decomposition of SO 3 in a heat recuperated (integrated)-PBR and also to maximize SO 3 conversion. DPM and simulation studies are carried out using COMSOL® and the model is validated with experimental studies. Experiments are performed at different flow rates, wall temperature, feed concentration and with two catalyst loadings, where chromium doped iron oxide 'foam' type (porous particle) catalyst is used. Simulation study shows, increase in conversion with decrease in particle size, annular gap and with increase in porosity, thermal conductivity of catalyst. Catalyst size is found to be an insignificant parameter, for porosity >0.2 and thermal conductivity is found to be a significant parameter. A conversion close to isothermal conversion has been obtained with the tuned parameters. H 2 SO 4 decomposer and SO 3 -concentration profiles (DPM profile) in bulk fluid and within the catalyst particle of an integrated-PBR. [Display omitted] • H 2 SO 4 decomposition study in heat recuperative decomposer made out of Silicon Carbide. • Double-porosity modeling of heat recuperative-PBR for catalytic-decomposition of SO 3. • Modeling of heat and mass transfer resistances in catalyst bed and catalyst particles. • Validation of double-porosity model using parametric experimental studies. • Catalyst and packed bed parameter tuning for maximising SO 3 -conversion in PBR. [ABSTRACT FROM AUTHOR]

Ion exchange resins and immobilized lipase as heterogeneous catalysts are used to synthesize biodiesel for alternative fossil fuels. The use of ion exchange resins in the solid and activated phase can ease the separation process. Furthermore, resins can be reactivated and used repeatedly, reducing the need for catalysts. On the other hand, an immobilized enzyme is biodegradable and can catalyze the transesterification process to produce biodiesel with a lower alcohol-to-oil ratio, minimizing side reactions and impurities. Therefore, the catalysts used in this study are ion exchange resins, such as Lewatit MP-64, Amberlite IRA410Cl, and Diaion PK208LH, as well as immobilized Candida rugosa lipase. By using vegetable oil as a feedstock and methanol for the transesterification, biodiesel production was carried out in a packed bed reactor. The present study aims to investigate the optimum process parameters, including the concentration of resin and enzyme, resin activation time, resin types, flowrate, and stability of resin and enzyme on the biodiesel yield. The results showed that the optimum conditions for biodiesel production with ion exchange resin were 4 g of resin, activated for 3 h, and synthesized for 3 h; Lewatit obtained a biodiesel yield of 94.06%, Amberlite obtained 90.00%, and Diaion obtained 73.88%. Additionally, the stability test of the reactivated Lewatit resin showed that it still has the capability of producing biodiesel with a yield of more than 80% after three regeneration cycles. In contrast, Candida rugosa lipase as was immobilized by entrapment in sodium alginate before being used in the biodiesel production for 12 h. The results showed that lower flowrate in enzymatic biodiesel synthesis produced a higher amount of biodiesel, of up to 71.1%. Nonetheless, immobilized lipases can be used up to three times without a significant loss in biodiesel yield. [ABSTRACT FROM AUTHOR]

This research suggests a comprehensive 3D model for modelling photocatalytic conversion of CO2 to methane, hydrogen and carbon monoxide in a packed bed reactor. This research includes two parts: designing the reactor's geometry using a new method in ''blender'' and using the computational fluid dynamics (CFD) technique to study and analyse the reaction, transport of phenomenon and light intensity through the reactor. Laminar flow, chemical reaction, mass transfer and optics physics were considered together to solve the equations. The surface reaction in the reactor follows a modified version of the Langmuir-Hinshelwood equation that evaluates the light profile in the reactor and the blockage of the catalyst's surface over time. Thus, a new method for 3D modelling light profiles in the reactor is introduced. The rate of reaction continues to increase with the pressure, and after 1 atm, the rate becomes steady. In the first 17 h, the methane rate is the highest, and then the carbon monoxide rate overcomes the methane rate. The rate of hydrogen is considerably lower than the other products. Changing pellets from spheres to Raschig rings causes growth in the probability density function (PDF) at the first moments. In methane's PDF, the amount of Raschig and sphere are 0.25 and 0.18, respectively, at the start of the reaction. Thus, the Raschig ring operates more effectively at the beginning moments of the process but eventually is outweighed after an hour by spherical particles. In the end, the validation of modelling and results were investigated with the aid of experimental data.

A method based on particle‐resolved CFD is built and validated, to calculate the fluid‐to‐particle mass and heat transfer coefficients in packed beds of spheres with different tube‐to‐particle diameter ratios (N) and of various particle shapes with N = 5.23. This method is characterized by considering axial dispersion. The mass and heat transfer coefficients increase by 5%–57% and 9%–63% after considering axial dispersion, indicating axial dispersion should be included in the method. The mass and heat transfer coefficients are reduced as N decreases. The catalyst particles without inner holes show higher mass and heat transfer coefficients than the ones with inner holes, because of unfavorable fluid flow in inner holes. The bed of trilobes has the highest mass and heat transfer coefficients, being 85% and 95% higher than the one of spheres. This work provides a versatile method and some useful guidance for the design of packed bed reactors. [ABSTRACT FROM AUTHOR]

This work evaluated the pyrolytic products from spent coffee residue pyrolysis in a fixed-bed reactor. The effects of the heating rate and temperature on the main pyrolytic products were investigated using a factorial experimental design. The average product yields obtained were liquid (49.45 wt%), char (26.45 wt%), and gas (24.05 wt%). Temperature was the most significant factor affecting product yield. Maximum devolatilization occurred at 823 K and 80 K/min, the same conditions that minimized the char yield. The spent coffee ground (SCG) decomposition occurred mainly due to a dehydration reaction, followed by decarboxylation. The heating rate and temperature directly influenced the production of phenols, and the formation of esters and ketones was favored at 723 K. Statistical analysis of the biochar element composition showed a carbon enrichment and a decrease in oxygen, hydrogen, and nitrogen contents at higher temperatures due to strong devolatilization. Char polarity and aromaticity were strongly affected by the temperature. The C/N ratios of the SCG chars (18.4–20.7) indicated that these chars are possible soil additives. [ABSTRACT FROM AUTHOR]

• Sorption-enhanced methanation in a Ni-13X zeolite packed beds network was modelled. • Autothermal continuous operation of the proposed system can be achieved. • High purity (Y CH4 > 99 %) methane stream can be produced under optimal conditions. • For any given GHVS value, an increase in operating pressure increases methane purity. The present study investigates a sorption-enhanced methanation process and successive solid regeneration stages using a dual-function catalyst containing nickel as a catalyst and zeolite 13X for water removal. An adiabatic packed bed, modelled by a dynamical and heterogeneous model, has been considered, and a five-stage sequence describes the sorption-enhanced methanation and successive solid regeneration. First, methanation occurs with in-situ water removal; then, the catalyst drying using a pressure and temperature swing approach implemented by blowdown, purge, cooling, and pressurisation stages. In adiabatic operation, heat management is crucial; on the other hand, the heat produced can be efficiently used to dry the zeolite. Process intensification is pursued by addressing the effect of gas inlet temperature, pressure, and GHSV on system performance. Achieving an average purity of 99 % of the methane for pressures greater than 2 bar is possible for long-time operation, with productivity averaging 0.8 mol/(kg ads min) at the highest gas hourly space velocity investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solid-state fermentation (SSF) to produce biostimulant and biopesticide was studied. • SSF was carried out at bench scale using green waste and Trichoderma harzianum. • The production of biostimulant at bench-scale was higher than that at lab-scale. • Porosity is one of the basic indicators of a successful SSF at bench-scale. • Sequential batch experiment was conducted as a strategy to scale up the production. This study aimed to develop a bench-scale process of solid-state fermentation (SSF) to produce biostimulants (indole-3-acetic acid-IAA) by Trichoderma harzianum CECT 2929, utilizing green waste as substrate. Additionally, biopesticide activity (in form of conidial spores) was also studied. The SSF was carried out in a 22-L packed bed reactor using grass clippings as the main substrate and pruning waste or wood chips as bulking agent. When using pruning waste, IAA production reached 62 µg/g dry matter, while the fermentation with wood chips resulted in a higher IAA concentration of 120 µg/g dry matter. Higher spore counts were reached using wood chips (9.5 × 108 and 1.3 × 109 spores g−1 dry matter, respectively). Further experiments showed that decreasing tryptophan as precursor for IAA production from 0.43 % to 0.2 % (w/w) significantly decreased IAA production from 120 to 25 µg/g dry matter while it did not alter spore production. In addition, a sequential batch operational strategy was explored, consisting of four consecutive batches as a strategy to scale-up the SSF process. The highest IAA and spore productions were achieved in the first batch, resulting in 119 µg/g dry matter and 1.1 × 109 spores g−1 dry matter, respectively. Subsequent batches showed a decline in production, particularly in batches 3 and 4, due to contamination issues. Summarizing, the strategies proposed in this study are a considerable advance to develop SSF to produce biostimulant and biopesticide agents in the context of circular bioeconomy, using green waste as raw material. [ABSTRACT FROM AUTHOR]

[Display omitted] • Addition of sodium thiosulfate and sodium acetate enhanced denitrification process. • EPS secretion was promoted and microbial community structure changed considerably. • Thiobacillus , Sulfuricella , Sulfuritalea and some heterotrophic denitrifiers enriched. • External electron donors upregulated the functional S-related genes such as sox. • The encoding of nitrite reductase and nitric oxide reductase was improved. Two parallel pilot-scale reactors were operated to investigate pollutant removal performance and metabolic pathways in elemental sulfur-driven autotrophic denitrification (SDAD) process under low temperature and after addition of external electron donors. The results showed that low temperature slightly inhibited SDAD (average total nitrogen removal of ∼4.7 mg L−1) while supplement of sodium thiosulfate (stage 2) and sodium acetate (stage 3) enhanced denitrification and secretion of extracellular polymeric substances (EPS), leading to the average removal rate of 0.75 and 1.01 kg N m−3 d−1, respectively with over twice higher total EPS. Correspondingly, nitrogen and sulfur related microbial metabolisms especially nitrite reductase and nitric oxide reductase encoding were promoted by genera including Thermomonas and Thiobacillus. The variations revealed that extra sodium acetate improved denitrification and enriched more SDAD-related microorganisms compared with sodium thiosulfate, which potentially catalyzed the refinement of practical strategies for optimizing denitrification in low carbon to nitrogen ratio wastewater treatment. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is one of the toxic chemicals, which is widely used for manufacturing epoxy, polyester resin, and polycarbonates. These materials are extensively used in manufacturing of reusable bottles, baby bottles, dental sealants, various medical devices, and so forth. Moreover, canned and packaged foods are sources of bisphenol A, which is unknowingly consumed by many people worldwide. Its endocrine disrupting and teratogenic properties impose potential risk to the wildlife and human health. BPA has been linked to reproductive, metabolic, and immunity disorders in humans. Regardless of BPA ban in reusable and baby bottles, annually, 15 billion pounds of BPA still being produced. BPA pollution and its cleanup are major challenges. Therefore, it is essential to develop a suitable strategy to bioremediate BPA. The Trametes versicolor (TV) laccase‐based nanoemulsion calcium alginate bead organogel was able to transform 94% of BPA within 2 h of treatment. Organogel showed 60% of BPA removal from actual industrial wastewater in packed bed batch reactor and 67% of BPA removal in continuous flow packed bed reactor. The biological oxygen demand (BOD) of treated industrial effluent was 14 mg/L, which is very much less than untreated effluent's BOD, which was 48 mg/L. The chemical oxygen demand of industrial effluent was 1240 mg/ml, and treated effluent was 248 mg/L, respectively. Hence, application of nanoemulsion‐based organogel in packed bed reactor found to be a potential candidate for the bioremediation of industrial effluent containing BPA. Practitioner Points: The TV laccase‐based nanoemulsion calcium alginate bead organogel was able to transform 94% of BPA.Organogel showed 67% of BPA removal from industrial wastewater in continuous flow packed bed reactor.The nanoemulsion‐based organogel in packed bed reactor found to be potential candidate for the bioremediation of industrial effluent containing BPA. [ABSTRACT FROM AUTHOR]

To save energy and increase treatment efficiency, a visible-light photocatalysis system was coupled with a biological treatment system for the continuous removal of phthalate esters (PAEs) from synthetic wastewater. Di-(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and dimethyl phthalate (DMP) were treated using an iodine-doped TiO2 photocatalyst, and the reactions followed first-order kinetics (similar to ultraviolet TiO2 photocatalysis) to produce phthalic acid as an intermediate product. The effects of various operating factors, such as PAE concentrations, pH, light intensity, retention time (RT), and the coexistence of PAEs, on individual PAE removal were investigated. DEHP-degrading bacteria were isolated from DEHP-contaminated soil, purified through serial dilution, and then identified through DNA sequencing. The results indicated that the optimal operating conditions for PAE removal with a visible-light photoreactor were a pH of 5, a temperature of 30 °C, a light intensity of 300 W, and an RT of 5.5 min. DEHP, which contains long and branched chains, was more difficult to degrade than DMP, which contains short alkyl side chains. Pseudomonas sp. was the most dominant bacteria in the DEHP-contaminated soil and was inoculated in a packed bed reactor (PBR) for complete PAE degradation. The effluent containing PAEs was pretreated using the visible-light photoreactor under a short RT. This treatment resulted in the effluent becoming biodegradable, and PAEs could be completely removed from the treated effluent by using the PBR. The coupled photobiological system achieved removal efficiencies of 99.6%, 99.9%, and 100% for DEHP, DBP, and DMP, respectively, during the continuous treatment. The results of this study indicate that the developed coupled system is an effective, energy-saving, and cost-efficient tool for treating wastewater containing PAEs. [ABSTRACT FROM AUTHOR]

In this study, batch experiments were conducted to evaluate the degradation of 4-CP using acclimated sludge. The Monod and Haldane models were employed to fit the specific growth rate with various initial 4-CP concentrations of 67–412 mg/L in the batch experiments. Haldane kinetics showed a better fit to experimental results than Monod kinetics. The kinetic parameters were obtained from a comparison of Monod and Haldane kinetics with batch experimental data. The values of μm and KS were found to be 0.691 d−1 and 5.62 mg/L, respectively, for Monod kinetics. In contrast, the values of μm, KS, and KI were 1.30 d−1, 8.38 mg/L, and 279.4 mg/L, respectively, for Haldane kinetics. The kinetic parameters in Haldane kinetics were used as input parameters for the kinetic model system of the packed bed reactor (PBR). The continuous flow PBR was conducted to validate the kinetic model system. The model-simulated results agreed well with experimental data in the PBR performance operation. At the steady-state stage, the removal efficiency of 4-CP was 70.8–96.1%, while the hydraulic retention time (HRT) was 2.5 to 12.4 h. The corresponding removal of 4-CP was assessed to be 94.6 and 96.1% when the inlet 4-CP loading rate was increased from 0.11 to 0.51 kg/m3-d. The approaches of kinetic models and experiments presented in this study can be applied to design a PBR for 4-CP treatment in wastewater from the effluents of various industries. [ABSTRACT FROM AUTHOR]

BACKGROUND: Fructooligosaccharides (FOS) are prebiotic sugars used in the production of functional foods. These sugars can be produced by the transfructosylation reaction of sucrose catalyzed by fructosyltransferase enzymes (FTase, E.C.2.4.1.9). The aim of this work was to evaluate the use of cells of Aspergillus oryzae IPT‐301 as biocatalysts for the sucrose transfructosylation reaction in a packed bed reactor (PBR). RESULTS: The morphology of the cells was observed by scanning electron microscopy, and BET specific surface areas were examined by nitrogen physisorption The highest transfructosylation activity (660 U g−1) of the cells was obtained at 25 min of reaction by adopting a reaction temperature of 50 °C, sucrose concentration of 470 g L−1, and volumetric flow of 15 mL min−1. The rise in volumetric flow provided an increase in the transfructosylation activity, but also a faster deactivation of the biocatalyst. Enzyme kinetics was described using the Michaelis–Menten model, with a Vmax of 632.8 U g−1 and a km of 160.7 g L−1. The cells showed constant enzymatic activity for 12 h of reaction in the PBR operated with discontinuous flow at flow rates of 5 mL min−1 and 11.5 mL min−1, and in the PBR operated with continuous flow at a flow rate of 5 mL min−1. The transition from diffusional to kinetic regimes was observed starting from 11.5 mL min−1. CONCLUSION: The results obtained suggest a high potential of application of the whole A. oryzae IPT‐301 cells for continuous FOS production in PBR. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Wastewater discharge from the leather manufacturing process involves various operations such as beam house, tanning and post-tanning. The conventional treatment system does not efficiently treat these kinds of wastewaters without the generation of any secondary pollutant. Mostly vast quantities of chemicals are added to the wastewaters to adjust pH to favour the treatment units that results in a huge amount of primary chemical sludge. This paper reports a new treatment approach by mixing various tannery operational wastewaters in the appropriate treatment units to adjust pH instead of adding chemicals. It also designed a treatment sequence to simultaneously treat all tannery operational wastewaters in such a way to suit their biodegradability and to avoid sludge to a greater extent. The treated water resulted in biochemical oxygen demand, 58 ± 39 mg L−1; chemical oxygen demand, 305 ± 35 mg L−1; total organic carbon, 94.93 ± 45.46 mg L−1; total nitrogen, 295 ± 226 mg L−1; ammoniacal nitrogen, 146 ± 75 mg L−1. [ABSTRACT FROM AUTHOR]

Nowadays, protecting the environment is of utmost importance worldwide, and sulfur dioxide is one of the main pollutants in the atmosphere. This work proposes a new method for simultaneous SO2 removal by MgO, and production of magnesium sulfate in a packed bed reactor for which breakthrough curves have been obtained. Furthermore, the effect of important operating parameters, including temperature, SO2 concentration, and gaseous flow rate was investigated. Experiments showed that increasing the temperature improved the breakthrough lifetime, but the increase in concentration and flow rate reduced the lifetime. The experimental results were predicted successfully by applying the Random Pore Model (RPM). Finally, the Non-dominated Sorting Genetic Algorithm II (NSGA II) that is a technique for multi-objective optimization, was employed to determine the best operating parameters for SO2 removal by magnesium oxide in the packed bed reactor.

• Coupled two-stage chemical–bioreactor system for PCB bioleaching and Fe3+ regeneration. • High bioleaching efficiency achieved in one- and two-stage reactor systems. • Microbial culture maintained their activity at a high PCB loading of 18% w/v. • Improvement of 60 % in Fe3+ regeneration rates in the two-stage reactor system. We report the bio-assisted leaching of PCBs in a continuous two-stage reactor system, comprised of a stirred tank reactor for chemical leaching of PCBs through the reduction of ferric iron, coupled to a packed-bed column bioreactor in which biological ferrous iron oxidation is optimised to regenerate the ferric leach agent. The bioreactor was packed with polyurethane foam biomass support particles colonised with the moderately thermophilic mixed culture, dominated by Leptospirillum ferriphilum. On chemical leaching of the PCBs with acidic ferric iron in the stirred tank reactor, a ferrous-rich solution was generated and circulated through the packed bed bioreactor to re-oxidise the ferrous iron to ferric iron. A one-stage reactor system, where both PCB leaching and re-oxidation of the resultant ferrous iron occur in one pot, was run concurrently. PCB loading was varied from 3 % to 18 % (w/v) and the regeneration of the required ferric iron for leaching was studied. In both one- and two-stage systems, high bioleaching efficiency was achieved, with the two-stage system achieving 98 % Al, 58 % Ca, 93 % Cr, 96 % Cu, >100 % Mg, 79 % Ni, 80 % Pb, >100 % Sn, >100 % Zn solubilisation from 18 % PCB solid loading, whereas low release of 7 % Co and 11 % Sr was achieved. Despite the high PCB solid loading, microbial cultures maintained their oxidative activity post exposure to the leached metals, with more rapid Fe3+ regeneration occurring in the two-stage system compared to the one-stage system. The two-stage reactor system exhibited an improvement of about 60 % in the ratio of the Fe3+ reduction and regeneration rates relative to the one-stage reactor system. These findings present a promising approach to maximising metal recovery while maintaining and improving microbial activity in the bioleaching of PCBs. Such insight into the bioleaching of the elemental form of base metals from PCBs at the reactor level contributes to process design and optimisation, to enable upscaling and subsequent commercialisation of the process. [ABSTRACT FROM AUTHOR]

Radial heat management is crucial for a safe and stable operation of fixed-bed reactors with small tube-to-particle diameter ratios (N). Under high temperature conditions, thermal radiation can contribute substantially to the overall heat transfer. In the present work, the influence of radiation is studied with particle resolved computational fluid dynamics (PRCFD) in a fixed-bed reactor consisting of 1000 spheres and rings with N = 5.1 over 300 < Re p < 2000 and for three different temperature levels (300–800 ∘C). Two heat transfer parameters, i.e., the wall Nusselt number Nu w and the effective radial thermal conductivity of the bed k eff , r , are derived directly from PRCFD. While the radiation effect is minor in k eff , r , it is substantial for Nu w , which is not captured adequately in the current correlations presented in literature. Depending on the temperature level and flow conditions, thermal radiation between the hot wall and the packed bed intensifies the radial heat transfer represented by an increase of up to 170 % in Nu w and 65% in k eff , r. A 2D axisymmetric pseudo-homogeneous model including the derived heat transfer parameters can predict the radial temperature profile of the PRCFD with reasonable accuracy also with radiation except for the near-wall region. [Display omitted] • Thermal radiation contributes substantially to the radial heat transfer in fixed-bed reactors. • For slender packed beds, it is dominant especially in the near-wall region. • Nu w and k eff,r were derived directly from particle-resolved CFD simulations. • Radiation effects in Nu w can be up to 170% and in k eff,r up to 65%. • Current literature correlations do not adequately capture these effects. [ABSTRACT FROM AUTHOR]

• Granulation synthesis route of (Mn 0.99 Si 0.01) 2 O 3 thermochemical material. • Analysis of chemical and mechanical stability of the granules. • Doubling the energy storage density though optimizing the process. • Satisfactory stability behavior in a lab-scale packed bed reactor. • The granules were subjected to 100 redox cycles. High temperature thermochemical energy storage still requires a significant research effort. Most of the research has been carried out with materials at lab-scale, and proper material fabrication techniques need to be developed in order to make feasible the upscaling of the technology. Agglomeration, abrasion, or low volumetric energy density are some negative consequences observed when trying to pass from the powder state to the material shape and amount required for a thermochemical reactor. In this work, an established granulation technique is investigated, using a Si-doped manganese oxide as active material to determine the critical parameters that provide the best chemical and mechanical stability of the granules. The granulation process uses a polymeric binder to give consistency to the granules and later, it is removed to create a porous structure to facilitate the oxygen diffusion in and out of the granule. We identified the positive effect of decreasing the bath temperature to increase the volumetric energy density of the granules. Furthermore, it was observed that increasing the mechanical stability through a high temperature treatment did not decrease the chemical stability of the material. In order to provide the first insights into the scalability of the solution, the chemical and mechanical stability of the granules have been satisfactorily checked during 100 redox cycles, out of which 50 were carried out in a home-made lab-scale packed bed reactor with an inner diameter of 13 mm and another 50 redox cycles in a simultaneous thermal analyzer. [ABSTRACT FROM AUTHOR]