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Open-cell metallic foams used as catalyst supports exhibit excellent transport properties. In this work, a unique application of metallic foam, as pelletized catalyst in a packed bed reactor, is examined. By using a wall-segment Computational Fluid Dynamics (CFD) setup, parametric analyses are carried out to investigate the influence of foam morphologies (cell size ϕ=0.45–3mm and porosity ε=0.55–0.95) and intrinsic conductivity on flow and heat transport characteristics in a slender packed bed (N=D/dp=6.78) made of cylindrical metallic foam pellets. The transport processes have been modeled using an extended version of conventional particle-resolved CFD, i.e., flow and energy in inter-particle spaces are fully resolved, whereas the porous-media model is used for the effective transport processes inside highly-porous foam pellets. Simulation inputs include the processing parameters relevant to Steam Methane Reforming (SMR), analyzed for low (Rep~100) and high (Rep~5000) flow regimes. The effect of foam morphologies on packed beds has shown that the desired requirements contradict each other, i.e., an increase in cell size and porosity favors the reduction in pressure drop, but, it reduces the heat transfer efficiency. A design study is also conducted to find the optimum foam morphology of a cylindrical foam pellet at a higher Rep~5000, which yields ϕ = 0.45, ε = 0.8. Suitable correlations to predict the friction factor and the overall heat transfer coefficient in a foam-packed bed have been presented, which consider the effect of different foam morphologies over a range of particle Reynolds number, 100≤Rep≤5000.

Using a Ca(OH)2/CaO thermochemical heat storage system is an effective way to promote the utilization of renewable energy. However, poor thermal conductivity restricts the application of a widely used fixed-bed reactor. To improve the heat storage rate, the internal heating mode, which heats the reactant via the internal heating tube instead of the external wall, was adopted, and the heat storage process in the fixed-bed reactor was investigated numerically. The results show that the number and location of tubes have a significant impact on heat storage performance. Compared with the external wall heating mode, the optimized scheme of six internal heating tubes can shorten the reaction time by 21.78%. The temperature and reaction extent distribution reveal that as the reaction proceeds, the optimized scheme has a higher temperature and reaction extent. Additionally, the effects of different conditions, such as solid particle porosity, wall temperature, outlet pressure, and solid particle size, were also analyzed. The study demonstrates that increases in solid particle porosity, wall temperature, and solid particle size as well as a decrease in outlet pressure can improve the heat storage rate.

The degradation of organic matter present in olive mill wastewater (OMW) and the recovery of water were studied by the integration of catalytic wet peroxidation (CWPO) and direct contact membrane distillation (DCMD) for the first time. The oxidation step was performed in a fixed–bed reactor (FBR) working in continuous mode (pH0 = 4.0 ± 0.2, 60 ◦C, Q = 0.75 mL/min, [H2O2]/[COD]feed = 2.3 ± 0.1 g H2O2/g O2). Samples of OMW diluted by 5– and 7.5–fold were used (OMW–5× and OMW–7.5×, respectively), corresponding to inlet chemical oxygen demand (COD) values of 3562 ± 68 and 2335 ± 54 mg/L, total phenolic content (TPh) of 177 ± 17 and 143 ± 7 mg GAeq/L, and total organic carbon (TOC) of 1258 ± 63 and 842 ± 45 mg/L, respectively. The FBR was loaded with 2.0 g of a Fe–activated carbon derived–catalyst, prepared by using olive stones as the precursor, in line with a circular economy model approach. The catalyst was selected based on the activity and stability towards polyphenolic synthetic solutions shown in previous works of the team, while actual OMW samples were used in this work. CWPO–treated samples of OMW allowed the operation of the DCMD unit at higher fluxes than with the analogous untreated ones, also showing higher rejections of organic matter from the feed solution upon DCMD, highlighting the beneficial effect of this novel configuration. Using a pre-treated sample of OMW–7.5× as feed solution (Q = 100 mL/min, Tpermeate ≈ 18 ◦C, Tfeed ≈ 66 ◦C), the produced permeate water stream presented several parameters well–below the legislated thresholds required for direct discharge for crops irrigation, including total suspended solids (TSS < 10 mg/L), TPh (, Portuguese Foundation for Science and Technology LA/P/0045/2020 UIDB/00511/2020 UIDP/00511/2020, European Regional Development Funds (ERDF) through North Portugal Regional Operational Programme (NORTE 2020) NORTE-01-0145-FEDER000069, NORTE 2020 under the PORTUGAL 2020 Partnership Agreement through ERDF NORTE-01-0145-FEDER000069, MCIN/AEI/FEDER "Una manera de hacer Europa" RTI2018-099224B-I00, Portuguese Foundation for Science and Technology BaseUIDB/50020/2020 UIDP/50020/2020, Portuguese Foundation for Science and Technology, European Commission SFRH/BD/129235/2017, National and the European Social Funds through the Human Capital Operational Programme (POCH) MCIN/AEI RYC-2019026634I, European Social Found (FSE) "El FSE invierte en tu futuro" RYC-2019026634I

This paper represents a detailed techno-economic analysis of a typical commercial-scale catalytic decarboxylation process of naphthenic acids over HZSM-5 zeolite. Simulation of the process has been performed in ASPEN Plus®. The performance of the modeled unit was compared to experimental results data from a similar plant. Two models were developed for the proposed industrial plant based on continuous flow reactors; the first is based on a fluidized bed reactor, and it was modeled as a continuous stirred tank reactor (CSTR) unit, and the second is a semi-regenerative process that consists of three fixed-bed reactors with intermediate preheaters and are modeled as three plug flow reactors (PFR). The outcome of the economic analysis of the two proposed commercial scale reactors of a decarboxylation process of a capacity of 11,000 bbl/day showed that the CAPEX, including the total equipment cost for the fluidized bed reactor plant and semi-regenerative process plant, was $44,319,362 and $4,447,919, respectively. The annual operating cost for the fluidized bed plant and semi-regenerative process plant is 45,269,180 $/year and 1,771,839 $/year, respectively. Our results demonstrated that catalytic decarboxylation over HZSM-5 zeolite is economically feasible using a semi-regenerative process, and is a promising method for removing naphthenic acid. The insight obtained from this work can be used as a basis for more comprehensive future financial and risk modeling of the process. The cost estimated in this work was compared to the Khartoum refinery cost for the naphthenic acid corrosion mitigation system, with a saving of $29,459,528.

Calcium looping integrated with chemical looping combustion (CaL-CLC) process is an efficient and cost-effective CO2 capture technology. In this technique, the heat generated by chemical looping combustion of CuO is used insitu to calcine CaCO3, thus avoiding the implementation of the energy-intensive air separation unit (ASU) in the conventional calcium looping (CaL) process for postcombustion CO2 capture. Many studies, including simulation works and material development, have been carried out on the CaL-CLC process. It is thus imperative to present the recent progress in the CaL-CLC process whilst providing a research prospects framework and direction for future research. First, fundamental understandings of the CaL-CLC process are discussed, including its concept and potential applications. Then, simulation work is reviewed, emphasizing process design and analysis, as well as modeling of the reactor and main reactions involved in the CaL-CLC process. Due to the fast reactivity decay of bifunctional CaO/CuO composites, various strategies have been developed to overcome this issue, which are summarized in detail. Last, future research directions for the CaL-CLC process are proposed.

Carbon deposits are well known to cover the ?-alumina surface when exposed to high temperatures in the presence of carbonaceous feedstocks by means of coking and/or fouling mechanisms. Herein, it is demonstrated that this phenomenon, which is extremely undesirable when ?-alumina is used as a catalyst or an adsorbent material, can be successfully exploited for the production of fluorescent carbon-based quantum nanodots (CQDs) under mild conditions of temperatures (250-300 °C) and time (30 min) by using residual biomasses as a carbon source. Specifically, four agro-industrial residues including sugar beet pulp (SBP), grape marc, tomato peels and seeds, and olive pomace have been successfully tested for the synthesis of biomass-based CQDs. Different techniques including UV-vis spectroscopy, fluorescence spectroscopy (PL), X-ray photoelectron spectroscopy, Raman spectroscopy, and transmission electron microscopy (TEM) have been applied for the characterization of the as-prepared SBP-based CQDs. Results highlight that the obtained carbon dots exhibit excellent solubility in both water and organic media. In addition, TEM investigations show that such nanoparticles disclose a rather uniform spherical morphology and a narrow size distribution in the range of 2-4 nm. The typical excitation dependent PL emission behavior of carbon-based quantum dots was also observed by PL analysis. Unlike other currently available bottom-up synthesis routes, a high-value by-product is obtained during the synthesis of biomass-based CQDs assisted by ?-AlO, i.e., the residual thermally treated biomass, which can be further valorized as a high-quality solid biofuel exhibiting a lower oxygen-to-carbon ratio and, hence, a higher calorific value than the parent biomass. The innovative finding of the present work is that a catalyst can be used to produce CQDs from the volatile matter that is driven off the biomass by heating, which opens up new possibilities of valorization for the off-gas substream coming from other biomass conversion process, like for example slow pyrolysis and carbonization.

Pyrolysis is a low-emission and sustainable thermochemical technique used in the production of biofuels, which can be used as an alternative to fossil fuels. Understanding the kinetic characterization of biomass pyrolysis is essential for process upscaling and optimization. There is no accepted model that can predict pyrolysis kinetics over a wide range of pyrolysis conditions and biomass types. This study investigates whether or not the classical lumped kinetic model with a three-competitive reaction scheme can accurately predict the walnut shell pyrolysis product yields. The experimental data were obtained from walnut shell pyrolysis experiments at different temperatures (300–600 °C) using a fixed-bed reactor. The chosen reaction scheme was in good agreement with our experimental data for low temperatures, where the primary degradation of biomass occurred (300 and 400 °C). However, at higher temperatures, there was less agreement with the model, indicating that some other reactions may occur at such temperatures. Hence, further studies are needed to investigate the use of detailed reaction schemes to accurately predict the char, tar, and gas yields for all types of biomass pyrolysis.

Background The search for sustainable energy sources has become a worldwide issue, making the development of efficient biofuel production processes a priority. Immobilization of second-generation (2G) xylose-fermenting Saccharomyces cerevisiae strains is a promising approach to achieve economic viability of 2G bioethanol production from undetoxified hydrolysates through operation at high cell load and mitigation of inhibitor toxicity. In addition, the use of a fixed-bed reactor can contribute to establish an efficient process because of its distinct advantages, such as high conversion rate per weight of biocatalyst and reuse of biocatalyst. Results This work assessed the influence of alginate entrapment on the tolerance of recombinant S. cerevisiae to acetic acid. Encapsulated GSE16-T18SI.1 (T18) yeast showed an outstanding performance in repeated batch fermentations with cell recycling in YPX medium supplemented with 8 g/L acetic acid (pH 5.2), achieving 10 cycles without significant loss of productivity. In the fixed-bed bioreactor, a high xylose fermentation rate with ethanol yield and productivity values of 0.38 gethanol/gsugars and 5.7 g/L/h, respectively were achieved in fermentations using undetoxified sugarcane bagasse hemicellulose hydrolysate, with and without medium recirculation. Conclusions The performance of recombinant strains developed for 2G ethanol production can be boosted strongly by cell immobilization in alginate gels. Yeast encapsulation allows conducting fermentations in repeated batch mode in fixed-bed bioreactors with high xylose assimilation rate and high ethanol productivity using undetoxified hemicellulose hydrolysate.

WOS: 000449265800050, The pyrolysis of almond shell as a biomass feedstock was performed in order to obtain a bio-based feedstock for bio-refineries in a fixed-bed reactor under inert atmosphere (occurred by N-2 gas) at certain experimental conditions including 500 degrees C of temperature and a heating rate of 10 degrees C min(-1). Then, the catalytic cracking of obtained pyrolytic liquid was conducted by using bentonite clay as a low-cost catalyst material at the conditions of 400 degrees C of temperature, a heating rate of 10 degrees C min(-1) and catalyst ratio of 30 wt%. The upgraded bio-oil revealed the properties of a basic fuel including 4.01 cSt of viscosity at the temperature of 40 degrees C; approximately 45.22% lower than that of non-upgraded bio-oil, low density of 1100.78 kg m(-3) at 15.6 degrees C, H/C molar ratio of 1.413 and calorific value (HHV) of 26.92 MJ kg(-1). The results of the chromatographic and spectroscopic analysis of the obtained bio-oils have revealed that the presence of bentonite clay led to a considerable increase in some organic compound groups such as phenolic, ketones, and oxygenated aromatics.

Eight different pellets (one woody and seven blends of woody and herbaceous biomass) produced by an agro-industry were tested in a fixed-bed reactor to characterize their behaviour during their combustion process. The objective was to analyze the possible problems that could arise and, thus, achieve advances in the greater penetration of these agropellets in the energy market. The blends’ design and tests results are presented in the first part of this article. The results of the bottom ash and fly ash samples obtained from the combustion tests using SEM-EDS and P-XRD techniques were analyzed in order to delve into the sintering and deposition phenomena, respectively. Regarding the sintering, a clear relationship has been found between the results of the SEM-EDS analysis and the initial composition of the ash of the fuels. Additionally, the analysis of the results confirms a different ash behaviour regarding the sintering phenomenon depending on the ratio between the amounts of Si, Ca + Mg and K + Na. With respect to deposition, it has been determined that in woody pellets, showing the lower sintering degree, the predominant deposition mechanism is by inertial impact, while in blend pellets it is by condensation, which increases when the percentage of herbaceous in the mixture increases. It has been proved that, in order to compensate (at least partially) for the negative effect of the herbaceous components in the blends, working with a higher λ value is interesting, as it achieves a decrease in the combustion temperature (with λ >1), which implies both a decrease in the sintering degree and in the deposition, improving therefore the ash behaviour in the combustion of agropellets.

In this study, we develop physics-informed neural networks (PINNs) to solve an isothermal fixed-bed (IFB) model for catalytic CO2 methanation. The PINN includes a feed-forward artificial neural network (FF-ANN) and physics-informed constraints, such as governing equations, boundary conditions, and reaction kinetics. The most effective PINN structure consists of 5–7 hidden layers, 256 neurons per layer, and a hyperbolic tangent (tanh) activation function. The forward PINN model solves the plug-flow reactor model of the IFB, whereas the inverse PINN model reveals an unknown effectiveness factor involved in the reaction kinetics. The forward PINN shows excellent extrapolation performance with an accuracy of 88.1% when concentrations outside the training domain are predicted using only one-sixth of the entire domain. The inverse PINN model identifies an unknown effectiveness factor with an error of 0.3%, even for a small number of observation datasets (e.g., 20 sets). These results suggest that forward and inverse PINNs can be used in the solution and system identification of fixed-bed models with chemical reaction kinetics.

Background The search for sustainable energy sources has become a worldwide issue, making the development of efficient biofuel production processes a priority. Immobilization of second-generation (2G) xylose-fermenting Saccharomyces cerevisiae strains is a promising approach to achieve economic viability of 2G bioethanol production from undetoxified hydrolysates through operation at high cell load and mitigation of inhibitor toxicity. In addition, the use of a fixed-bed reactor can contribute to establish an efficient process because of its distinct advantages, such as high conversion rate per weight of biocatalyst and reuse of biocatalyst. Results This work assessed the influence of alginate entrapment on the tolerance of recombinant S. cerevisiae to acetic acid. Encapsulated GSE16-T18SI.1 (T18) yeast showed an outstanding performance in repeated batch fermentations with cell recycling in YPX medium supplemented with 8 g/L acetic acid (pH 5.2), achieving 10 cycles without significant loss of productivity. In the fixed-bed bioreactor, a high xylose fermentation rate with ethanol yield and productivity values of 0.38 gethanol/gsugars and 5.7 g/L/h, respectively were achieved in fermentations using undetoxified sugarcane bagasse hemicellulose hydrolysate, with and without medium recirculation. Conclusions The performance of recombinant strains developed for 2G ethanol production can be boosted strongly by cell immobilization in alginate gels. Yeast encapsulation allows conducting fermentations in repeated batch mode in fixed-bed bioreactors with high xylose assimilation rate and high ethanol productivity using undetoxified hemicellulose hydrolysate.

The benefits of H-ZSM-5 zeolite modification with H3PO4 or ZnCl2 have been analyzed during the methanol to olefins (MTO) reaction. The catalysts were prepared, characterized and tested using three different reactors: fixed-bed, operando FTIR and UV-vis. The spent catalysts were further characterized for analyzing the nature and location of the species trapped. The results show that the zeolite modified with H3PO4 has suffered a simultaneous dealumination, leading to a decrease of number of acid sites and activity. However, the zeolite modified with ZnCl2 shows the inclusion of Zn transforming Brønsted into Lewis acid sites, leading to reaction intermediates (hydrocarbon pool species) that decreases the rate of reaction but improves propylene selectivity (+10%), slows downs coke formation (-42%) and expands catalytic lifetime (+80%). The distinct effect of Zn modification, typically associated with the promotion of aromatics, is explained on the grounds of the severe transformation of the strong and Brønsted acid sites. This work was possible thanks to the financial support of the Ministry of Economy, Industry and Competitiveness of the Spanish Government (Project CTQ2016-79646-P, co-founded with ERDF funds) and the Basque Government (Project IT748-13, IT912-16). J.V. is thankful for his fellowship granted by the Ministry of Economy, Industry and Competitiveness of the Spanish Government (BES-2014-069980). The authors are thankful for technical and human support provided by IZO-SGI SGIker of UPV/EHU and European funding (ERDF and ESF).

In this paper we have investigated and demonstrated the antimicrobial capabilities of nano-silver-4 wt%-kaolin (nAg-4-Kn) composite supported on borosilicate glass beads (BGB). Tests have been conducted in a fixed bed reactor on effluent from the secondary clarifier of a conventional wastewater treatment plant (WWTP) in Abu Dhabi, United Arab Emirates (UAE). The prepared BGB with immobilized nAg-4-Kn (nAg-4-Kn/BGB) were characterized using the RAMAN spectroscopy, TEM equipped with EDX and Focus Ion Beam Scanning Electron Microscope (FIB-SEM) techniques. The rate of disinfection was assessed through Luria-Bertani (LB)-agar plate cell counting technique. The results showed complete disinfection after few hours, which was preserved even after several days in repeated runs. The nAg-4-Kn/BGB was reused, demonstrating that the immobilization of nAg-4-Kn was stably achieved, and the activity and integrity of the composites on the BGB were preserved. First order disinfection kinetic constants were estimated to be 2.76 cm h−1 and 2.56 cm h−1 in two consecutive runs. Analyses of the beads after the experiments showed minor losses of nAg from the kaolin matrix thereby corroborating reusability of these materials.

A methodology for photocatalytic reactor modeling applied to advanced oxidation processes for chemical pollution abatement is presented herein. Three distinct reactor configurations typically employed in the field of air and water purification?wall reactors, slurry reactors, and fixed-bed reactors?are considered to illustrate the suggested approach. Initially, different mechanistically derived kinetic expressions to represent the photocatalytic rate of pollutant degradation are reviewed, indicating the main assumptions made by the authors in the published contributions. These kinetic expressions are needed to solve the mass balances of the reactant species in the photocatalytic reactors. As is well known, at least one of the steps of the reaction mechanism requires evaluation of the rate of electron?hole generation, which depends on the photon absorption rate: a volumetric property for reactions with the catalyst particles in aqueous suspension or a surface property for systems with a fixed catalyst deposited on an inert support. Subsequently, the different techniques for evaluating the optical properties of slurry and immobilized systems, and the numerical methods applied to calculate the photon absorption rate, are described. The experimental and theoretical results of pollutant degradation in each reactor type are then presented and analyzed. Finally, the definition, calculation, and relevance of different efficiency parameters are briefly reviewed. Using these illustrative examples, we emphasize the need for a systematic and rigorous approach for photocatalytic reactor modeling in order to overcome the inherent drawbacks of photocatalysis and to improve the overall efficiency of the process. Fil: Ballari, Maria de Los Milagros. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Satuf, María Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina

This work presents the photocatalytic degradation of the pharmaceutical drug clofibric acid in a fixed-bed reactor filled with TiO2-coated glass rings. Experiments were carried out under UV radiation. A kinetic model that takes into account radiation absorption by means of the local surface rate of photon absorption (LSRPA) has been developed. The LSRPA was obtained from the results of a radiation model. The Monte Carlo method was employed to solve the radiation model, where the interaction between photons and TiO2-coated rings was considered. Data from experiments carried out with rings with different number of catalyst coatings and different irradiation levels were used to estimate the parameters of the kinetic model. A satisfactory agreement was obtained between model simulations and experimental results. Fil: Manassero, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Satuf, María Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina

The hydrogen production from ammonia decomposition on commercial 5 wt.% Ru/C (C: activated carbon) catalyst with different cesium (Cs) loadings at lower temperatures of 325–400 °C in the fixed-bed reactor was experimentally investigated. Based on the parameters used in this work, the results showed that the ammonia conversion at 350 °C is increased with the increasing Cs/Ru molar ratio, and it reaches its maximum value at the Cs/Ru molar ratio of 4.5. After that, it is rapidly decreased with a further increase of Cs/Ru molar ratio, and it is even smaller than that of the pure Ru/C case at the Cs/Ru molar ratio of 6. The Cs promotion at the lower Cs/Ru molar ratios may be due to the so-called “hot ring promotion”. The possible mechanisms for Cs effects on the ammonia conversion at higher Cs/Ru molar ratio are discussed. At optimum Cs loading, the results showed that all the ammonia conversions at 400 °C are near 100% for the GHSV (gas hourly space velocity) from 48,257 to 241,287 mL/(h·gcat).

Two-dimensional 1H magnetic resonance imaging and spatially-resolved 1H magnetic resonance spectroscopy and diffusion measurements were recorded as a function of time-on-stream within a fixed-bed reactor to provide direct measurements of the progress of the heterogeneous catalytic oligomerization of ethene occurring over a 1 wt% Ni-Al2O3-SiO2 catalyst. The catalyst bed was of internal diameter 2 cm; magnetic resonance measurements were recorded over a bed length of 5.5 cm. Experiments were conducted at a temperature and pressure of 110 °C and 29 bara, respectively, with continuous downflow of ethene at a flowrate of 0.78 L h−1. During conversion the accumulation of 1H-containing species within the catalyst pellets was imaged, and spatially-resolved 1H NMR spectra were recorded at 1 mm intervals along the length of the reactor. Diffusion-filtered 1D chemical shift imaging was used to discriminate between gas- and liquid-phase species along the length of the reactor at 1 mm intervals. Finally, spectrally-encoded pulsed field gradient measurements of molecular diffusion were employed to infer the molecular composition of the gas and liquid phases and to identify populations of these phases inside and external to the pore space of the catalyst pellets; these measurements were spatially-resolved along the length of the reactor, with data being averaged over sections of height 4 mm. The results are consistent with oligomers of carbon number C20 and greater existing within the pores of the catalyst pellets which act to block the pore space, thereby deactivating the catalyst.

Slow pyrolysis (200–650 °C) experiments on citrus residues (orange peel waste “OP” and lemon peel waste “LP”) were carried out in lab scale fixed bed batch reactor. Bio-oil and bio-char obtained by thermal degradation are more stable, more homogeneous and higher energy content fuels when compared to the parent feedstock. Thermogravimetric analysis (TGA) showed higher stability of LP waste, which appears related to the higher lignin content . Mass and energy yields of solid and liquid products (i.e., char and oil) were measured to determine the effects of peak temperature on feedstock. A linear correlation between Gross Calorific Value (GCV), peak temperatures and mass loss (ML) allows easy analytical calculation of energy properties of residues in the range between 200 °C and 325 °C (peak temperatures). Highest GCV and energy density (ED) of bio-chars are obtained at 500 °C peak temperature for both LP and OP residues: ED LP_CHAR = 1.70, ED OP_CHAR = 1.75. Char reactivities were measured in TGA in a nitrogen atmosphere. High temperature chars (500 and 600 °C) showed a higher reactivity than low temperature ones, between 100 °C and 400 °C. This higher reactivity may be explained by the higher thermal conductivity due to higher ash content and higher surface area of high temperature chars. The tars extracted from pyrolytic bio-oil showed GCVs of approximately 19,700 and 17,000 J/g for LP and OP, respectively, independently of pyrolysis peak temperature. Despite the difference in the GCVs, both LP and OP tars show nearly identical FT-IR spectra denoting the presence of very similar chemical species, mainly phenolic, polyaromatics, ketones, ethers and carboxylic acids.

Today’s needs of energy are yet globally dominated by fossil energy sources, causing the depletion of non-renewable energy. Alternatively, a potential substitute is the energy of biomass. Spirulina platensis (SP) is a microalgae biomass which, if extracted, will produce solid waste called Spirulina platensis residue (SPR). This research explores the pyrolysis product, produced within the range of 300 – 600 ºC, from the pyrolysis of SP and SPR using fixed bed reactors. The influence of temperature on pyrolysis product’s yield and characteristics are investigated by using mass balance method and gas chromatography – mass spectrometry (GC-MS) technique, respectively. The results from mass balance method present an optimum pyrolysis temperature of 550 ºC to obtain the desired liquid product of bio-oil, presenting the percentage of 34.59 wt.% for SP and 33.44 wt.% for SPR case. Additionally, with the increasing temperature, the char yield decreases for about 30 wt.% and the yield of gas seems to sharp increase from 550 to 600 ºC. These tendencies are both applied for SP and SPR source pyrolysis product. Interestingly, the benefit use as fossil fuel substitute might be derived, thanks to high HHV at the bio-oil product (32.04 MJ/kg for SP and 25.70 MJ/kg for SPR) and also at the char product with of 18.85-26.12 MJ/kg for both cases. The additional benefit come from the high content of C in its char product (50.31 wt.% for SPR and 45.26 wt.% for SP) that might be able to be used as an adsorbent, soil softener or other uses in the pharmaceutical field. ©2019. CBIORE-IJRED. All rights reserved

The β-galactosidase from Bacillus circulans was covalently attached to aldehyde-activated (glyoxal) agarose beads and assayed for the continuous production of galactooligosaccharides (GOS) in a packed-bed reactor (PBR). The immobilization was fast (1 h) and the activity of the resulting biocatalyst was 97.4 U/g measured with o-nitrophenyl-β-d-galactopyranoside (ONPG). The biocatalyst showed excellent operational stability in 14 successive 20 min reaction cycles at 45 °C in a batch reactor. A continuous process for GOS synthesis was operated for 213 h at 0.2 mL/min and 45 °C using 100 g/L of lactose as a feed solution. The efficiency of the PBR slightly decreased with time; however, the maximum GOS concentration (24.2 g/L) was obtained after 48 h of operation, which corresponded to 48.6% lactose conversion and thus to maximum transgalactosylation activity. HPAEC-PAD analysis showed that the two major GOS were the trisaccharide Gal-β(1→4)-Gal-β(1→4)-Glc and the tetrasaccharide Gal-β(1→4)-Gal-β(1→4)-Gal-β(1→4)-Glc. The PBR was also assessed in the production of GOS from milk as a feed solution. The stability of the bioreactor was satisfactory during the first 8 h of operation; after that, a decrease in the flow rate was observed, probably due to partial clogging of the column. This work represents a step forward in the continuous production of GOS employing fixed-bed reactors with immobilized β-galactosidases., This work was supported by grants from the Spanish Ministry of Economy and Competitiveness (BIO2013-48779-C4-1-R and BIO2016-76601-C3-1-R). We thank the support of COST-Action CM1303 on Systems Biocatalysis. P.S.-M. thanks the Spanish Ministry of Education for FPU Grant (FPU13/01185). We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).

The aim of this study was to evaluate the application of the anaerobic bioreactor with fixed-structured bed (ABFSB) for brewery wastewater treatment with high volumetric organic loading rate (VOLR) and its comparison with a traditional packed-fixed bed bioreactor. Two different biomass support materials were tested, including polyurethane (PU) and polypropylene (PP) for both configurations. The best global efficiency was reached by the structured-fixed bed reactor with polyurethane as biomass support (SB PU). For a VOLR of 14.0 kg CODt m-3 d-1 (HRT of 8 h) and 20.3 kg CODt m-3 d-1(HRT of 12 h), the SB PU reached the average CODt removal efficiencies (ECOD) of 81% and 71%, respectively. The results show that ABFSB is a promising technology for high organic matter and solids concentration wastewater treatment, but the type of the biomass support had a big impact on the reactors performance.

WOS: 000246113600004, A study of pyrolysis of olive cake at the temperature range from 400 degrees C to 700 degrees C has been carried out. The experiments were performed in a laboratory scale tubular reactor under nitrogen atmosphere. The yields of derived gases, liquids, and char were determined in relation to pyrolysis temperature and sweeping gas flow rates, at heating rates of about 300 degrees C min(-1). As the pyrolysis temperature was increased, the percentage mass of char decreased whilst gas product increased. The oil products increased to a maximum value of similar to 39.4 wt% of dry ash free biomass at a pyrolysis temperature of about 550 degrees C in a nitrogen atmosphere with flow rate of 100 mL min(-1) and with a heating rate of 300 degrees C min(-1). Results showed that the bio-oil obtained under the optimum conditions is a useful substitute for fossil fuels or chemicals.

Fischer-Tropsch synthesis (FTS) is a heterogeneously catalyzed chemical reaction in which a mixture of hydrogen and carbon-monoxide is converted into an array of hydrocarbon products. These products can be used as synthetic liquid fuels (gasoline, diesel, kerosene) or feedstock for the chemical industry. As such, FTS is a key step in the conversion of coal, natural gas and biomass into liquids in large plants all over the world, including plants in Qatar, Malaysia, South Africa etc. Even though FTS has been commercially used for most of the 20th century, many fundamental aspects of this reaction are unclear. The main objectives of the work included in this thesis were: to study the effect of process conditions on FTS product selectivity and distribution with regards to hydrocarbon chain length, develop a detailed model of FTS kinetics (capable of predicting both reactant disappearance and product formation rates) and apply the detailed kinetic model in modeling and optimization of a multi-tubular fixed-bed reactor for FTS. Most often used catalysts for FTS are iron and cobalt. The experimental data used in this study were obtained in collaboration with Texas A&M University and Center for Applied Energy Research, University of Kentucky, for iron- and cobalt-based catalyst, respectively. The analysis of experimental data for both catalysts showed dependence of product selectivity from process conditions inside the reactor (temperature, pressure, reactant feed ratio and conversion level). These dependences were shown to be related to the chain-growth probability factor (α), which also varies with carbon number. Over the cobalt catalyst, the significant variation of C1 intermediate growth probability (α1) at different process conditions and a lack of the same variations for higher C2+ chain intermediates, was interpreted as evidence for the existence of separate methanation pathways. The same data presented evidence that the secondary 1-olefin readsorption does not play a major part in determining FTS selectivity. For the iron-based catalysts, similar correlations between variations of growth probability with process conditions were found. However, existence of additional pathways for methane formation and relevance of secondary olefin reactions could not be confirmed for that catalyst... Fischer-Tropsch sinteza (FTS) je heterogeno katalizovana hemijska reakcija u kojoj se smeša vodonika i ugljen-monoksida pretvara u niz ugljovodoničnih proizvoda. Ti proizvodi se mogu koristiti kao sintetička tečna goriva (benzin, dizel i kerozin) ili sirovine za hemijsku industriju. Kao takva, FTS je ključni korak u konverziji uglja, prirodnog gasa i biomase u tečnosti u velikim postrojenjima širom sveta, uključujući postrojenja u Kataru, Maleziji, Južnoj Africi itd. Iako je FTS veći deo dvadesetog veka bila u komercijalnoj upotrebi, mnogi fundamentalni aspekti ove reakcije su nejasni. Glavni ciljevi istraživačkog rada u sklopu ove disertacije su bili: ispitivanje efekata procesnih uslova na selektivnost i raspodelu FTS proizvoda u odnosu na dužinu ugljovodoničnog lanca, razvoj detaljnog kinetičkog modela FTS (sposobnog da ujedno predskaže brzine nestajanja reaktanata i nastajanja proizvoda) i primena detaljnog kinetičkog modela u modelovanju i optimizaciji višecevnih FTS reaktora sa pakovanim slojem katalizatora. Najčešće korišćeni katalizatori za FTS su gvožđe i kobalt. Eksperimentalni podaci za gvozdeni i kobaltni katalizator korišćeni u ovoj studiji su dobijeni u saradnji sa Texas A&M Univerzitetom (Texas A&M University) i Centrom za primenjeno istrazivanje energije Univerziteta u Kentakiju (Center for Applied Energy Research, University of Kentucky), respektivno. Analiza eksperimentalnih podataka za oba katalizatora je pokazala zavisnost selektivnosti proizvoda reakcije of procesnih uslova unutar reaktora (temperature, pritiska, odnosa reaktanata u ulaznoj smeši i konverzije reaktanata). Pokazano je da su ove zavisnosti povezane sa verovatnoćom rasta ugljovodoničnog lanca (α), koja se takođe menja sa brojem atoma ugljenika. Značajne varijacije u vrednosti verovatnoće rasta C1 lančanih intermedijera pri različitim procesnim uslovima, zabeležene sa kobaltnim katalizatorom, kao i odsustvo istih varijacija za duže C2+ lančane intermedijere, su interpretirane kao dokaz postojanja dodatnog reakcionog puta za metanaciju. Isti rezultati su poslužili kao dokaz da sekundarne reakcije 1-alkena ne igraju bitnu ulogu u određivanju selektivnosti FTS. Slične korelacije između promena verovatnoće rasta lanca i procesnih uslova su zapažene i sa gvozdenim katalizatorom. Međutim, postojanje dodatnog reakcionog puta za formiranje metana i važnost sekundarnih reakcija alkena nisu potvrđene za taj katalzator...

Conversion of electrical energy into chemical energy carriers has the potential to replace fossil fuels and can be attractive as long-term storage. The present work considers different aspects of the electricity-to-fuel process chain using a combination of experimental work and mathematical modelling. This work discusses in detail the production of gaseous hydrocarbons from H2 and CO2 via Fischer-Tropsch synthesis and the potential to operate fixed-bed reactors under flexible conditions.

WOS: 000178050800007, Sunflower (Helianthus annus L.)-oil cake pyrolysis experiments were achieved in a fixed-bed tubular reactor. The effects of nitrogen flow rate and final pyrolysis temperature on the pyrolysis product yields and chemical compositions have been investigated. The maximum bio-oil yield of 48.69 wt% was obtained in nitrogen atmosphere with nitrogen flow rate of 100 cm(3) min(-1) and at a pyrolysis temperature of 550 degreesC with a heating rate of 5 degreesC s(-1). Chromatographic and spectroscopic studies on the pyrolytic oil showed that the oil obtained from sunflower-oil cake can be used as a renewable fuel and chemical feedstocks

WOS: 000167375600007, Sunflower (Helianthus annus L.)-extracted bagasse pyrolysis experiments were performed in a fixed-bed reactor. The effects of heating rate, final pyrolysis temperature, particle size and pyrolysis atmosphere on the pyrolysis product yields and chemical compositions have been investigated. The maximum oil yield of 23% was obtained in N(2) atmosphere at a pyrolysis temperature of 550 degreesC and a heating rate of 7 degreesC min(-1). The chemical characterization has shown that the oil obtained from sunflower-extracted bagasse may be potentially valuable as fuel and chemical feedstocks

The kinetic rate of the heterogeneously catalysed methane oxidation reaction was studied at temperatures ranging from 723 to 923 K and atmospheric pressure. A commercially available CuO catalyst supported by thermally stable γ-Al2O3 was used as the catalyst. This kinetic study was carried out in order to evaluate whether this reaction can be suitably handled in a novel type of membrane reactor (J.W. Veldsink et al., Chem. Eng. Sci., 47 (9–11) (1992) 2939–2944). The equipment in which the experiments were conducted consisted of a differentially operated fixed-bed reactor. For this set-up heat and mass transport limitations have been checked and shown to be absent. The influence of the concentrations of the products and reactants on the reaction rate was studied over a wide range of conditions. Fractions of methane ranged from 1 to 6 vol.%, oxygen between 600 ppm and 21 vol.%, carbon dioxide between 0 and 20 vol.%, and water from 0 to 8 vol.%. All experimentally observed reaction rates could be represented within 30% by an Eley-Rideal type reaction rate expression.

The combined processes of biological As III oxidation and removal of As III and As V by zero-valent iron were investigated with synthetic water containing high As III concentration (10 mg L −1 ). Two up-flow fixed-bed reactors (R1 and R2) were filled with 2 L of sieved sand ( d = 3 ± 1 mm) while zero-valent iron powder ( d = 76 μm; 1% (w/w) of sand) was mixed evenly with sand in R2. Thiomonas arsenivorans was inoculated in the two reactors. The pilot unit was studied for 33 days, with HRT of 4 and 1 h. The maximal As III oxidation rate was 8.36 mg h −1 L −1 in R1 and about 45% of total As was removed in R2 for an HRT of 1 h. A first order model fitted well with the As III concentration evolution at the different levels in R1. At the end of the pilot monitoring, batch tests were conducted with support collected at different levels in R1. They showed that bacterial As III oxidation rate was correlated with the axial length of reactor, which could be explained by biomass distribution in reactor or by bacterial activity. In opposition, As III oxidation rate was not stable in R2 due to the simultaneous bacterial As III oxidation and chemical removal by zero-valent iron and its oxidant products. However, a durable removal of total As was realized and zero-valent iron was not saturated by As over 33 days in R2. Furthermore, the influence of zero-valent iron and its oxidant corrosion products on the evolution of As III -oxidizing bacteria diversity was highlighted by the molecular fingerprinting method of PCR-DGGE using aoxB gene as a functional marker of aerobic As III oxidizers.

In recent decades, the production of palatinose has aroused great interest since this structural isomer of sucrose has an interesting potential. Using immobilized in chitosan Serratia plymuthica cells, a complete conversion of concentrated sucrose solutions into palatinose was achieved in a “batch”-type enzyme reactor. Under typical process conditions, the specific productivity was in the range of 0.76–1.15 h −1 (kg sucrose converted, kg −1 catalyst). The effect of the inlet sucrose concentration (30–70%), the reaction temperature of 30–60 °C and the residence time (Rt) of the substrate solution on the specific volumetric productivity of the biocatalyst in a tubular fixed-bed reactor during continuous sucrose conversion into palatinose was studied. Residence time of 1.7–3.0 h was necessary for the achievement of 98–100% conversion of sucrose at substrate concentration of 30–50%. Considerably longer residence time (4–5 h) was needed for reaching the same conversion rate of concentrated sucrose solutions (60–70%). The composition of the outlet sugar solutions was investigated. The highest palatinose content was achieved (∼94%), when 40% inlet sucrose solution was used. It decreased in the case of more concentrated inlet sucrose solutions, but not below 78%. Operational stability of 155 days was achieved. The final value of the cumulative productivity of the reactor during continuous process of conversion was 1488 kg of palatinose produced per dm 3 of biocatalyst.

One of the interesting methods for conversion of synthesis gas to heavy hydrocarbons is Fischer–Tropsch process. The process has some bottlenecks, such as hot spot formation and low degree of conversion. In this work, computational fluid dynamics technique was used to simulate conversion of synthetic gas and product distribution. Also, hot spot formation in the catalytic fixed-bed reactor was investigated in several runs. Simulation results indicated that hot spot formation occurred more likely in the early and middle part of reactor due to high reaction rates. Based on the simulation results, the temperature of hot spots increased with increase in the inlet temperature as well as pressure. Among the many CFD runs conducted, it is found that the optimal temperature and pressure for Fischer–Tropsch synthesis are 565 K and 20 bar, respectively. As it seems that the reactor shall work very well under optimal conditions, the reaction rates and catalyst duration would simultaneously be maximum .

A lab-scale Plexiglas cubic container as a pre-aeration reactor with total volume of 10 L, and two integrated bioreactors including a moving-bed bioreactor (MBBR) and a fixed-bed bioreactor with total volume of 30 L separately were used for experimental study. The main purpose was to compare the performance of moving-bed and fixed-bed reactors for degradation of high organic loading in synthetic wastewater. Varying organic loadings of 0.5 to 9 kg COD m3 d–1 were applied. Generally, the total microbial mass in terms of attached biofim and VSS was higher in the MBBR. The microbial mass in the MBBR increased from 4120 to 4640 mg L–1 and in the fixed-bed bioreactor from 4124 to 4564 mg L–1. The COD removal efficiency in sequencing runs of operation in moving-bed and fixed-bed bioreactors varied from 96.27 % to 81.27 %, and from 95.2 % to 74.82 % respectively. The data obtained from this study indicate that MBBR, with the applied media in this study, was more efficient than the fixed-bed bioreactor for biodegradation of organic matter under identical operating conditions.

The methanation of carbon dioxide is an option for chemical storage of renewable energy together with greenhouse gas reutilization because it offers a product with a high energy density. The reaction CO2 + 4H(2) CH4 + 2H(2)O is performed on a Ru/Al2O3 catalyst and is strongly exothermal. For this reason, the reactor design must take into account an efficient thermal management system to limit the maximal temperature and guarantee high CO2 conversion. Additionally, the methanation reactor is subject to parameter sensitivity. This phenomenon can generate instability in the operation of a power to gas plant, due to the variability in the hydrogen production rate. Here we present a parametric study of the thermal properties of the reaction and determine the minimal feed temperature for the normal operation of a reactor. The minimal temperature required is determined by several parameters, such as pressure, space velocity and properties of the cooling system. For adiabatic reactors, the required feed temperature is 210 degrees C for a space velocity of 3000 h(-1) and a pressure of 10 bar. The space velocity strongly affects the positioning of the ignition point, causing a large variability of the feed temperature required. At the same time, the optimal working point of the reactor is at the minimal activation temperature. The properties of cooled reactors are elucidated, showing how the interrelationship between cooling and feed temperature makes the management of this class of reactors more challenging. On the base of the modelling results, we propose a reactor configuration that adjusts the thermodynamic limitations and respects the minimal requirements for reaction ignition, allowing a more stable operation and avoiding the functioning at excessive temperature.

The transesterification reaction employing supercritical methanol and carbon dioxide used as a co-solvent in the presence of several heterogeneous solid acid catalysts was investigated. The solid acid catalysts were prepared by impregnation methods, with appropriate precursors over magnesium aluminum silicate (cordierite). The catalysts tested were CeO2, WO3, ZnO, ZrO2, ZrO2-SO42-, mixed oxides (50-5096, w/w) WO3- ZrO2, CeO2-ZrO2, ZnO-La2O3, and Al2O3. Reaction tests were conducted at 200 degrees C and 20 MPa under the condition of 25:1 methanol/oil ratio at a space velocity of 4 mm with a fixed-bed continuous flow reactor containing ca. 5 g of catalyst. The best catalytic performance was obtained over ZrO2-SO42- with a yield toward fatty acid methyl esters (FAMEs) of 98%. This value is better to that obtained over the commercial catalyst Nafion SAC-13 (94%). The direct correlation between the conversion and catalyst total acidity was non-existent, but a positive effect of strong acid sites is evidenced.

In der vorliegenden Arbeit wurden 3D-CFD-Modelle entwickelt und angewandt, um Festbettreaktoren mit verschiedenartigen Festbettkonfigurationen und Reaktionen zu modellieren. Die Ergebnisse wurde durch Vergleich mit ortsaufgelösten Reaktorprofilen der Reaktantenkonzentrationen und Reaktortemperatur kritisch validiert. Die experimentellen Daten wurden auch zur Kalibrierung wichtiger Modellparameter verwendet. Der in dieser Arbeit gewählte Ansatz ist ein wertvolles Werkzeug für ein tieferes Verständnis des Zusammenspiels von Fluiddynamik, Wärme- und Stofftransport und der katalytischen Reaktion in Festbettreaktoren, und stellt einen Schritt in Richtung einer wissensbasierten Reaktorauslegung bzw. -optimierung dar., In this work, three-dimensional CFD models were developed and applied to simulate catalytic fixed bed reactors with different types of packing configuration and reactions. A spatially resolved profile measurement technique was applied in this work to critically validate the simulation results, and to calibrate parameters required in the model. This work demonstrates that detailed reactor modeling and profile measurements are useful tools for achieving an in-depth understanding of the interactions between flow, heat and mass transfer and catalytic reactions in fixed bed reactors. Furthermore, with the comprehensive knowledge gained from both methods, a knowledge-based reactor optimization approach can be put forward.