Trickle Bed Research Articles

Continuous aryl alcohol oxidase production under growth-limited conditions using a trickle bed reactor

An A. nidulans strain with a pyridoxine marker was used for continuous production of aryl alcohol oxidase (AAO) in a trickle bed reactor (TBR). Modified medium with reduced zinc, no copper, and 5 g/L ascorbic acid that reduced melanin production and increased AAO productivity under growth limited conditions was used. Two air flow rates, 0.11 L/min (0.1 vvm) and 1.1 L/min (1.0 vvm) were tested. More melanin formation and reduced protein productivity were observed with air flow rate of 1.1 L/min. Three random packings were used as support for the fungus inside the TBR column, two of which were hydrophobic and one which was hydrophilic, and three different dilution rates were tested. The use of GEA BCN 030 hydrophobic packing resulted in greater AAO yield and productivity than the other packings. Increasing dilution rates favored melanin formation and citric, lactic and succinic acid accumulation, which decreased AAO yield and productivity.

Application of Process Tomography to Multiphase Flow Measurement in Industrial and Biomedical Fields: A Review

This paper reviews the latest development and emerging technologies on the application of process tomography to multiphase flow measurement in industrial and biomedical fields. In the industrial applications, electrical resistance tomography and electrical capacitance tomography are popularly applied in multiphase flow measurement dependent on the electrical properties of the objects. In particular, applications to circulating fluidized bed, trickle-bed reactor and temperature measurement are discussed. In the biomedical applications, in most cases, measurement is conducted in a static condition. Two latest applications in flowing condition are reviewed, which are thrombus detection in blood flow and cell sensing with a microfluidic device. Finally, the challenges to process tomography for multiphase flow measurement on industrial and biomedical applications are addressed.

Fischer-Tropsch synthesis in vertical, inclined and oscillating trickle-bed reactors for offshore floating applications

Fischer-Tropsch synthesis performance in vertical, inclined and oscillating trickle-bed reactors for offshore floating applications was examined via a complex dynamic three-dimensional multiphase model based on volume-averaged mass, momentum, and species balance equations in liquid and gas phases and simultaneous diffusion and chemical reactions within the catalyst. Angular sinusoidal oscillatory motion of the trickle-bed reactor between vertical and an inclined position and between two inclined symmetrical/asymmetrical positions was examined. The behavior of inclined and oscillating Fischer-Tropsch trickle-bed reactors is atypical because the reactants in the main reactions originate from the gas phase and because a fraction of useful CO can be redirected in water gas-shift reaction. The performance of Fischer-Tropsch synthesis in the presence of water-gas shift reaction increases slightly with amplification of packed bed inclination even if the distortion of axial symmetry of liquid holdup and axial velocity radial distributions becomes considerable. Also, in asymmetric oscillating trickle-bed reactors the performance of Fischer-Tropsch synthesis is slightly improved. This enhancement is maximal for the reactor moving between vertical and an inclined position when the time-dependent waves of CO and H2 conversion develop around the steady-state solution of the middle inclination angle. The oscillatory Fischer-Tropsch performance moves towards the steady-state solution of the vertical state when the asymmetry between two inclined positions diminishes. Symmetric oscillating trickle-bed reactors generate an oscillatory Fischer-Tropsch performance around the steady-state solution of vertical state which is affected by the angular motion parameters of the reactor.

Catalyst used in fluid catalytic cracking (FCC) unit as a support of NiMoP catalyst for light cycle oil hydroprocessing

The behavior of the NiMoP catalysts prepared by means of impregnation of different supports (MCM-41, SBA-15, catalyst used in FCC unit) has been studied, using them in the hydroprocessing of Light Cycle Oil (LCO) with the aim of maximizing the sulfur removal and reduce polyaromatics content; so the hydroprocessed LCO can be hydrocracked in another unit with metal noble catalysts.Catalysts have been characterized through several techniques: N2 adsorption–desorption, elemental analysis (ICP-AES), X-ray diffraction (XRD), acidity measurement by temperature programmed desorption (TPD) of tert-butylamine, temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), UV–Vis spectroscopy, transmission electron microscopy (TEM), and temperature programmed oxidation (TPO) (spent catalysts). The hydroprocessing runs have been carried out in a fixed bed reactor working in trickle bed regime at 320–400 °C; 80 bar; H2:LCO ratio, 1000mLNH2mL−1LCO; space time, 0.2 h, and time on stream (TOS), 8 h.The catalyst NiMoP/HY-Al2O3 (spent FCC catalyst) stands out due to its high hydrodesulfurization activity attributable to the ease of impregnation of metals over FCC catalyst and the accessibility of the components of the LCO to the hierarchical porous structure. Its activity for reducing polyaromatics compounds of LCO is also remarkable, without diminishing the diesel fraction content by overcracking. Besides, the deposition of coke over this catalyst is scarce, since the retention of the high molecular weight molecules of LCO in its porous structure is minimized.

Trickle bed applied to the post‐treatment of blast furnace dust

AbstractThis study aims to develop an original filtration device based on a trickle bed technology which permits to treat high gas flow rates while maintaining a constant pressure drop by re‐entraining continuously the particles trapped on collectors, thanks to a water film flow. Good results have been obtained for an air flow rate of 20 m3/hr, a liquid flow rate of 12 L/min and using glass beads of 5‐mm diameter as collectors. Experimental results showed a good mass efficiency (89%) and a pressure drop which stabilizes under clogging unlike that of a granular bed which increases during the clogging. The experiments certifying a stable pressure drop during a few tens of hours let us suppose that these tendencies should be extrapolated to much larger times.

Hydrogenolysis of glycerol to 1,2‐propanediol in a continuous flow trickle bed reactor

AbstractBACKGROUNDHydrogenolysis of glycerol to glycols in continuous flow three phase reactors is of practical importance due to the need to give value to huge amounts of surplus glycerol. Thermodynamic and kinetic aspects must be revised for a proper design. The system was studied in a trickle‐bed reactor using copper chromite and Cu/Al2O3as catalysts.RESULTSPhase equilibrium and flow pattern were verified. Solid, liquid and gas phases were present, with the liquid phase in ‘trickling’ flow. Catalysts were characterized by inductively coupled plasma (ICP), nitrogen sortometry, X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), temperature programmed reduction (TPR) and pyridine thermal programmed desorption (TPD). The average reaction rate was found to be practically constant under different process conditions. A theoretical analysis indicated that the resistance to the transfer of hydrogen from the gas to the liquid phase dominated the overall kinetics. Selectivity to 1,2‐propanediol varied with temperature, with a maximum at 230 °C (97%). Selectivity was a function of the catalyst acidity. When the pressure was increased the selectivity to 1,2‐propanediol was increased, up to 97% at 14 bar. Higher pressures did not modify this value.CONCLUSIONSOptimum reaction conditions for maximum selectivity to 1,2‐propanediol with Cu‐based catalysts are 230 °C and 14 bar. System kinetics are, however, dominated by the gas–liquid mass transfer resistance. © 2017 Society of Chemical Industry

Large-Scale Exploitation of Bimodal Reaction Sequences Including Degradation: Comparison of Jet Loop and Trickle Bed Reactors

Product yield optimization in bimodal reaction sequences including degradation has been performed considering three-phase reactors such as the jet loop and trickle bed reactors. The considered reaction network comprises two consecutive homogeneous reaction steps toward intermediates which are converted to the corresponding final products by heterogeneously catalyzed reactions, while the reactant and these intermediates are susceptible to irreversible degradation. In the jet loop reactor, the so-called “homogeneous product” is the main product; hence, the remaining challenge is the reduction of degradation. For the trickle bed reactor, gas–liquid mass phase transfer plays a very pronounced role in its ultimate performance. Higher gas flow rates may be employed in the trickle bed reactor to overcome potential mass-transfer limitations and selectively form the “heterogeneous product”. Lower gas flow rates result in a less effective gas dissolution, and product selectivities change toward the homogeneous prod...

Modeling and Simulation of a Three Phase Fixed Bed Catalytic Reactor for the Hydrogenation of 2-ethyl-hexenal

The aim of this work is the investigation, by modelling and simulation, of the liquid phase hydrogenation of 2-ethyl-2-hexenal to 2-ethyl-hexanol, over a modern Cu-Ni catalyst, in an industrial tri-phase trickle bed reactor. The chemical kinetics, hydrodynamic parameters and mass transfer coefficients were evaluated from published data. The mathematical model of the process takes into consideration intraparticle and interphase concentration gradients. The calculated temperature evolution along the catalytic reactor is in a good agreement with measured values from an industrial plant. The results indicate that critical kinetic step of the process is the hydrogen transfer toward the inner catalyst surface and that the process occurs close to gas-liquid equilibrium. The degree of catalyst pellet utilization, evaluated by internal effectiveness factors, is relatively low, being mainly dependent on rapid exhaust of dissolved hydrogen inside the catalyst pellet. The presented results could be useful in process analysis, optimization and control studies.

Immobilization of Saccharomyces cerevisiae using polyethyleneimine grafted collagen fibre as support and investigations of its fermentation performance

ABSTRACTIn the present investigation, an collagen fibre (CF), abundant natural biomass, was successfully grafted by polyethyleneimine (PEI). The resultant PEI grafted collagen fibre (CF-PEI) was employed as biocompatible and high cell loading support matrix for the immobilization of Saccharomyces cerevisiae cells. The as-prepared CF-PEI immobilized cells (CF-PEI-cell) exhibited high activity and stability for both batch and continuous fermentation. In batch fermentation, CF-PEI-cells showed enhanced stability as compared with other matrices supported cells, and produced an average ethanol concentration of 45.04 g/L with ethanol yield (YP/S) of 0.46 g/g and glucose conversion efficiency (η) of 90.4%. Continuous fermentation was operated stably in a down-flow trickling bed reactor charged with CF-PEI-cell for a total of 2 months. When the dilution rate was 0.16 1/h, the average ethanol productivity reached 7.18 g/(L h) with η of 88.94%. Further scanning electron microscopy observations confirmed that yeast cells can proliferate on the surface of CF-PEI during ethanol fermentation, which demonstrates that CF-PEI is indeed an ideal matrix for the immobilization of yeast cells.

Predictive modeling and optimization for an industrial Coker Complex Hydrotreating unit – development and a case study

This work presents a model for UOP Coker Complex Hydrotreating Process using Aspen HYSYS Petroleum Refining module. The model depends on routinely taken industrial data of process streams during normal operating conditions. Acquired data sets have been tested and screened in order to ensure data validity for building the model and avoiding erroneous results. A detailed kinetic model of hydrotreating reactions in the reactor has been applied. The trickle bed reactor (TBR) model has been validated using 3 months of industrial plant data. In addition, rigorous tray-by-tray simulations for hydrogen sulfide absorption tower and TBR effluent fractionation tower have been utilized to match the performance of the plant’s towers. The model has been used then for studying the effects of different process variables on the plant performance. In addition, the model has been used in optimizing the operating conditions of the process. This optimization showed a potential for notable savings of fuel and energy consumption in the process, while increasing the process productivity.

Resolving Multiphase Flow through Packed Bed of Solid Particles Using eXtended Discrete Element Method with Porosity Calculation

Multiphase flow reactors such as trickle bed reactors are frequently used reactors in many industries. Understanding the fluid dynamics of these kinds of reactors is necessary to design and optimize them. The pressure drop and liquid saturation are the most important hydrodynamic parameters in these reactors, which depend highly on the porosity distribution inside the bed. The eXtended Discrete Element Method (XDEM) was applied as a numerical approach to model multiphase flow through packed beds of solid particles. This method has the ability to be coupled with Computational Fluid Dynamics (CFD) through interphase momentum transfer which makes it suitable for many Eulerian–Lagrangian systems. The XDEM also calculates the porosity distribution along the bed, which not only eliminates the empirical correlations but also makes it possible to investigate the maldistribution of liquid saturation inside the bed. The results for the hydrodynamics parameters were compared with experimental data, and satisfactory ...

On the production of bio-hydrogenated diesel over hydrotalcite-like supported palladium and ruthenium catalysts

Jatropha oil is a non-edible and promising feedstock for the manufacturing of renewable diesel by the process of catalytic hydrotreatment. The present work focuses on the production of diesel range hydrocarbons over hydrotalcite-like (HTlc) materials promoted with Pd and Ru. Catalytic activities of the materials were investigated in a trickle-bed reactor. The performance of these catalysts was assessed by studying the influence of various operating parameters like temperature, WHSV, pressure and H2/oil ratio. Our lab-made materials exhibited encouraging performance in terms of jatropha oil conversion and C15-C18 hydrocarbon yield. The maximum oil conversion was achieved at optimized reaction conditions, i.e. 91.2% with Pd and 85.6% with Ru catalyst. These results justify the impregnation of noble metals over HTlc-based materials owing to their high activity in hydrogenation. Both Pd/HTlc and Ru/HTlc catalysts remained stable for over 30h.

HDO of Methyl Palmitate over Silica-Supported Ni Phosphides: Insight into Ni/P Effect

Two sets of silica-supported nickel phosphide catalysts with a nickel content of about 2.5 and 10 wt % and Ni/P molar ratio 2/1, 1/1 and 1/2 in each set, were prepared by way of a temperature-programmed reduction method using (Ni(CH3COO)2) and ((NH4)2HPO4) as a precursor. The NixPy/SiO2 catalysts were characterized using chemical analysis N2 physisorption, XRD, TEM, 31P MAS NMR. Methyl palmitate hydrodeoxygenation (HDO) was performed in a trickle-bed reactor at 3 MPa and 290 °C with LHSV ranging from 0.3 to 16 h−1. The Ni/P ratio was found to affect the nickel phosphide phase composition, POx groups content and catalytic properties in methyl palmitate HDO with the TOF increased along with a decline of Ni/P ratio and a growth of POx groups’ content. Taking into account the possible routes of methyl palmitate conversion (metal-catalyzed hydrogenolysis or acid-catalyzed hydrolysis), we proposed that the enhancement of acid POx groups’ content with the Ni/P ratio decrease provides an enhancement of the rate of methyl palmitate conversion through the acceleration of acid-catalyzed hydrolysis.

Hydrogen Peroxide Generation in Divided-Cell Trickle Bed Electrochemical Reactor

A divided-cell trickle bed electrochemical reactor (TBER) with a porous cathode composed of carbon black and polytetrafluoroethylene was developed for generation of hydrogen peroxide. An important feature of the reactor is a divided cathode of different cells made with stainless steel mesh. This division into a sectional cathode resulted in a concentration of hydrogen peroxide that is more than twice that produced in an undivided cathode. The much improved performance was attributed to the even distribution of electrolyte and oxygen in the cathode bed, as well as an effective mass transport of oxygen from the gas phase to the electrolyte–cathode interface. Hydrogen peroxide generation was demonstrated from electrochemically reducing oxygen in concentrated alkaline electrolyte solutions using the TBER. Factors for the hydrogen peroxide electrosynthesis were systematically studied, including cell potential, electrolyte flow rates and concentrations, temperatures, and the number of cells.

An Eulerian‐Eulerian Computational Approach for Simulating Descending Gas‐Liquid Flows in Reactors with Solid Foam Internals

AbstractChemical reactors with new types of packings, such as metallic and ceramic open‐pore foams, have become subjects of scientific and engineering interest in the past decades. For trickle bed reactors, the new packing types provide favorable conditions, such as high specific surface area and low pressure drop, which are believed to contribute to an intensification of mass and heat transfer. Here, an attempt was made to model and predict the flow pattern and liquid distribution in a trickle bed reactor with solid foams, using computational fluid dynamics. A three‐dimensional model based on the relative permeability approach was adopted, where gas and liquid phases flow co‐currently downwards through a reactor with SiSiC ceramic foams as internals. The influence of both mechanical and capillary dispersion was included and studied in detail for foams of two different pore densities and for different initial distribution patterns.

Liquid Holdup by Gravimetric Recirculation Continuous Measurement Method. Application to Trickle Bed Reactors under Pressure at Laboratory Scale

Liquid holdup is a crucial parameter when operating catalytic trickle bed reactors related to wetting efficiency and residence time. Most of the classical methods are expensive, time-consuming, or not valid for high pressures. Liquid holdup by gravimetric recirculation (LHGR) measurement method determines the average total liquid holdup using a closed loop with total recirculation of liquid. The recirculating liquid is contained in a vessel that is weighed instantaneously with a known amount of liquid. The difference between the initial amount of liquid and the instantaneous weight gives the liquid holdup. Main benefits are the following: first, the measurement takes only the time of stabilization that at laboratory scale is 2–5 min; second, the system is ready for the next measurement without any modification (the bed is not disturbed nor modified); third, it works for high pressures; finally, it gives values comparable to those from classical techniques like RTD or conductivity methods.

Influence of operating pressure on the biological hydrogen methanation in trickle-bed reactors

In order to investigate the influence of pressures up to 9bar absolute on the productivity of trickle-bed reactors for biological methanation of hydrogen and carbon dioxide, experiments were carried out in a continuously operated experimental plant with three identical reactors. The pressure increase promises a longer residence time and improved mass transfer of H2 due to higher gas partial pressures. The study covers effects of different pressures on important parameters like gas hourly space velocity, methane formation rate, conversion rates and product gas quality. The methane content of 64.13±3.81vol-% at 1.5bar could be increased up to 86.51±0.49vol-% by raising the pressure to 9bar. Methane formation rates of up to 4.28±0.26m3m−3d−1 were achieved. Thus, pressure increase could significantly improve reactor performance.

Automated measurements of gas‐liquid mass transfer in micropacked bed reactors

Gas‐liquid mass transfer in micropacked bed reactors is characterized with an automated platform integrated with in‐line Fourier transform infrared spectroscopy. This setup enables screening of a multidimensional parameter space underlying absorption with chemical reaction. Volumetric gas‐liquid mass‐transfer coefficients (kLa) are determined for the model reaction of CO2 absorption in a methyl diethanolamine/water solution. Parametric studies are conducted varying gas and liquid superficial velocities, packed bed dimensions and packing particle sizes. The results show that kLa values are in the range of 0.12∼0.39 s−1, which is about one‐to‐two orders of magnitude larger than those of conventional trickle beds. An empirical correlation predicts kLa in micropacked bed reactors in good agreement with experimental data. © 2017 American Institute of Chemical Engineers AIChE J, 64: 564–570, 2018

Bromide and Acids: A Comprehensive Study on Their Role on the Hydrogen Peroxide Direct Synthesis

Hydrogen peroxide direct synthesis was studied using different concentrations of NaBr and H3PO4 (promoters) with a commercial Pd/C catalyst. The aim of the study was to understand the role of the acids and bromide on the catalyst and thus the effect on the direct synthesis. The experimental work was done in a continuous trickle bed reactor (TBR) using different concentrations of promoters. The effect of the promoters on the catalyst (Pd leaching and bromide adsorption) was monitored by inductively coupled plasma (ICP) on the solution obtained from the reaction environment. ICP analysis coupled with the monitoring of conversion, selectivity, and productivity helped to understand the effect of the promoters and to check the possibility to discriminate better the reaction network mechanism with different reaction conditions. Pd leaching was correlated to catalyst activity and bromide/phosphoric acid ratio. This work provides new and original evidence on the role of promoters, allowing one to understand bette...

High performance biological methanation in a thermophilic anaerobic trickle bed reactor

In order to enhance energy efficiency of biological methanation of CO2 and H2, this study investigated the performance of a thermophilic (55°C) anaerobic trickle bed reactor (ATBR) (58.1L) at ambient pressure. With a methane production rate of up to 15.4m3CH4/(m3trickle bed·d) at methane concentrations above 98%, the ATBR can easily compete with the performance of other mixed culture methanation reactors. Control of pH and nutrient supply turned out to be crucial for stable operation and was affected significantly by dilution due to metabolic water production, especially during demand-orientated operation. Considering practical applications, inoculation with digested sludge, containing a diverse biocenosis, showed high adaptive capacity due to intrinsic biological diversity. However, no macroscopic biofilm formation was observed at thermophilic conditions even after 313days of operation. The applied approach illustrates the high potential of thermophilic ATBRs as a very efficient energy conversion and storage technology.