Laboratory Scale Tubular Reactor Research Articles

Study of norfloxacin degradation by advanced oxidation process using UV/TiO2/H2O2 in an annular reactor

Norfloxacin (NFX) residual was frequently found in domestic wastewater, sewage treatment plants, hospital wastewater, and surface water like lakes and rivers. This threatens the ecological balance of the environment. Moreover, normal biological treatment methods (including membrane bioreactor - MBR) are not feasible for the removal of NFX. In this study, the degradation of NFX through advanced oxidation processes (AOPs) utilising UV/TiO2 and H2O2 as reagents in a laboratory-scale tubular reactor system was conducted. The degradation reactions of NFX could be represented by the Langmuir-Hinshelwood kinetic model. The influence of factors, including TiO2and H2O2 concentrations, UV irradiation intensity, and hydrodynamic conditions (specifically, Reynolds number), on the apparent reaction rate constant (kapp) was evaluated. The results demonstrated that the advanced oxidation process employing the combined reagents of UV/TiO2/H2O2 under the following reaction conditions: TiO2 and H2O2concentrations of 0.2 g/l and 0.0492 mol/l, UV irradiation intensity of 225 W/m2, and Reynolds number of 6700, achieved an apparent degradation reaction rate constant for NFX of 0.052 min-1.

Investigation of the Pyrolysis of Animal Manure in a Laboratory-Scale Tubular Reactor: The Effect of the Process Temperature and Residence Time

This paper focuses on the pyrolysis of animal manure in a laboratory-scale tubular reactor between 300 and 900°C at nitrogen flow rates of 1 and 5 dm3/h. During the experiments, it was found that both the temperature and nitrogen flow rate had significant effects on the product yields and compositions. The highest gas yield and syngas content were observed at 900°C at a nitrogen flow rate of 1 dm3/h. In this case, since the gaseous product was characterized by a H2/CO ratio of 0:5, its quality must be improved prior to being used for synthesis. The composition of the solid residue was also affected by the pyrolysis parameters. Based on the hydrogen/carbon and oxygen/carbon ratios, it was concluded that both the water-gas shift and Boudouard reactions were the most critical.

Meta-analysis approach for understanding the characteristics of CO2 reduction catalysts for renewable fuel production

The conversion of CO2 into renewable fuels by thermo-catalytic hydrogenation has been attempted by several researchers as this overcomes two significant problems, namely, greenhouse gas CO2 mitigation and renewable fuel production. Numerous experimental data have been reported in carbon-neutral methanol production using various copper, copper-zinc, copper-zinc-aluminium and also non-copper based catalysts in the past two decades. However, the lack of comprehensive data extraction and undefined data structure have concealed the property-performance correlations in catalyst design, which may have given a significant breakthrough in scaling up this carbon-neutral technology. This work attempts to review the literature data on this catalytic reaction considering various important catalyst descriptors starting from an elemental composition followed by correlating all the catalyst properties with performance using a meta-analysis approach. Herein, data for CO2 hydrogenation to C1 alcohol, methanol, was collected from 110 literature publications, and a comprehensive, structured interpretation of the catalysts' features that enhance their activity in this reaction is interpreted using meta-analysis. All the property groups, which are the key performance indicators, are analysed by testing their statistical significance across a wide range of reaction conditions under which the experimental data are collected from the literature. The developed machine learning model reveals that the promising catalyst must have the functionality to form stable carbonates. The adequacy of the model was validated through experimental data collected over eight different reaction conditions in a laboratory-scale tubular reactor. Thus, the meta-analysis tool is used to its full potential of exploring experimental data reported in past decades for the accurate design of CO2 reduction catalysts.

Kinetic Study Based on the Carbide Mechanism of a Co-Pt/γ-Al2O3 Fischer–Tropsch Catalyst Tested in a Laboratory-Scale Tubular Reactor

A Co-Pt/γ-Al2O3 catalyst was manufactured and tested for Fischer–Tropsch applications. Catalyst kinetic experiments were performed using a tubular fixed-bed reactor system. The operative conditions were varied between 478 and 503 K, 15 and 30 bar, H2/CO molar ratio 1.06 and 2.11 at a carbon monoxide conversion level of about 10%. Several kinetic models were derived, and a carbide mechanism model was chosen, taking into account an increasing value of termination energy for α-olefins with increasing carbon numbers. In order to assess catalyst suitability for the determination of reaction kinetics and comparability to similar Fischer–Tropsch Synthesis (FTS) applications, the catalyst was characterized with gas sorption analysis, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) techniques. The kinetic model developed is capable of describing the intrinsic behavior of the catalyst correctly. It accounts for the main deviations from the typical Anderson-Schulz-Flory distribution for Fischer–Tropsch products, with calculated activation energies and adsorption enthalpies in line with values available from the literature. The model suitably predicts the formation rates of methane and ethylene, as well as of the other α-olefins. Furthermore, it properly estimates high molecular weight n-paraffin formation up to carbon number C80.

Combustion of furniture wood waste and solid wood: Kinetic study and evolution of pollutants

This work is focused on the combustion processes of wood waste. Two kinds of waste have been studied: furniture wood waste (treated and used wood) and solid wood from factories (untreated wood). A kinetic study has been carried out for each material in air and an N2:O2 9:1 atmosphere with dynamic and dynamic+isothermal runs at different heating rates, considering the decomposition of the three main components of the wood and also the combustion of the char obtained. Satisfactory kinetic models were obtained for each kind of wood. Significant differences in thermal behavior were found between furniture wood waste and solid wood, probably due to the presence of additives and inorganic compounds in the furniture wood waste, which modifies the kinetic parameters of the thermal process.Moreover, combustion runs at 850°C of both kinds of woods were also carried out in a laboratory scale tubular reactor in order to analyze the volatile and semivolatile compounds. The main differences were found in the higher yield of nitrogenated compounds found during the combustion of the furniture wood waste.

Pyrolysis of furniture wood waste: Decomposition and gases evolved

The pyrolysis of furniture wood waste was studied due to its importance as a thermochemical conversion process, and also because it is a step in the combustion process. Furniture wood contains organic additives and inorganic elements (being noteworthy the high content of Ti). These additives cause changes in the thermal processes. A thermogravimetric analysis of the pyrolysis of furniture wood waste was carried out in a TGA apparatus using dynamic and dynamic+isothermal runs. The pyrolysis was modeled with acceptable approximation by three independent reactions, according to the decomposition of the main components of the wood (hemicellulose, cellulose and lignin). The gaseous products evolved during the pyrolysis were measured by the TG-MS and TG-FTIR techniques. The maximum formation of gases occurs around 360°C. The CO2 formation remains until the end of the run, due to the wide range of lignin degradation. In addition, runs to identify the volatile and semi-volatile compounds were also carried out in a laboratory scale tubular reactor at 500 and 850°C and the results were compared with the pyrolysis of a cleaner wood.

Continuous protein refolding in a tubular reactor

Continuous protein refolding by direct dilution was established in a laboratory-scale tubular reactor. Advanced refolding strategies by pulsed refolding and temperature leap, favoring the native pathway of specific model proteins were also implemented. The reactor was tested with two autoprotease fusion proteins, EDDIE-pep6His and 6His-EDDIE-GFPmut3.1, and also on carbonic anhydrase II. Direct refolding kinetics approximated by a folding kinetic of first order and aggregation kinetic of second order was similar to batch processes, while pulse and temperature leap refolding yields were higher than direct batch refolding method. Productivity comparisons calculated as amount of refolded protein per reactor volume and process time showed that an optimal refolding concentration to achieve highest productivity value is a balance between a rational reactor volume and a reasonable refolding time. Productivity in a tubular reactor is always higher as emptying and refilling times required for batch reactor decreases productivity. This productivity improvement is higher for a fast refolding protein than a slower one.

Olefin Production from Heavy Liquid Hydrocarbon Thermal Cracking: Kinetics and Product Distribution

Thermal cracking of a heavy liquid hydrocarbon was performed in a laboratory scale tubular reactor. Central Composite Design (CCD), was used as an experimental design method. The design variables were Coil Outlet Temperature (COT), feed flow and rate steam ratio. Maximum yield of ethylene was 30.37 wt% at COT, residence time and steam ratio of 869 o C, 0.208 s and 1.22 g/g, respectively. Maximum yield of propylene was 15.37 wt% at COT, residence time and steam ratio of 825 o C, 0.147 s and 0.95 g/g, respectively. A mechanistic model based on free radical chain reactions was developed using experimental results. Developed reaction network contains 148 reactions for 43 species. Finally, the experimental data were compared with model results. Scatter diagrams showed good agreement between model and experimental data.

Rapid liquefaction of Longkou lignite coal by using a tubular reactor under methane atmosphere

Rapid liquefaction of Longkou lignite coal under methane atmosphere was studied in a novel laboratory scale tubular reactor. Experiments were performed at a temperature ranging from 400 to 800 °C, a residence time ranging from 4.5 to 11.2 s and 10–15 MPa (without catalyst). Reactions were also carried out under a nitrogen gas atmosphere at the same reaction conditions. The results indicate that there are synergistic effects between coal and methane at temperatures higher than 600 °C, and the temperature and residence time are the main factors influencing the coal conversion and products distribution. The oil yields reach a maximum of 21.97 (wt.% daf) at 750 °C during 9.0 s.

Bio-oil Production from an Oilseed By-product: Fixed-bed Pyrolysis of Olive Cake

A study of pyrolysis of olive cake at the temperature range from 400°C to 700°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°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 ∼39.4 wt% of dry ash free biomass at a pyrolysis temperature of about 550°C in a nitrogen atmosphere with flow rate of 100 mL min−1 and with a heating rate of 300°C min−1. Results showed that the bio-oil obtained under the optimum conditions is a useful substitute for fossil fuels or chemicals.

Laboratory-scale study of the suppression of PCDD/F emission during coal and MSW co-incineration

The experimental test of co-incinerating Chinese raw municipal solid waste (MSW) and coal in a laboratory-scale tubular reactor was first reported in present study, and the emission of normal gas components and the effects of the S/Cl molar ratio or coal mixing percentages on polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDDs/Fs) emission were investigated and discussed. The results indicated that OCDD was the only PCDD homologues since others like TCDD-HpCDD was hardly detected, while as the categories of PCDF homologues were comparatively much more general. The amount of PCDD was much larger than that of PCDF in all operating conditions. Since ∑PCDF/∑PCDD<<1, the dominant role of the precursor formation was proven in our experimental conductions. With increasing the coal addition to MSW (from 0 to 16%), PCDD and PCDF were reduced considerably. Coal and MSW may suppress the PCDD/F emissions efficiently (over 95%) during the MSW incineration process. The PCDD/F suppression results of the present study could be helpful guidance to the industrial application of Chinese MSW and auxiliary coal co-incineration processes. The PCDD/F stack emission data of two industrial incinerators using co-incineration technology in China seem to have a great positive reduction of PCDDs/Fs.

Comparison of Microchannel and Fixed Bed Reactors for Selective Oxidation Reactions: Isoprene to Citraconic Anhydride

The selective oxidation of isoprene to citraconic anhydride over vanadia-supported catalysts is used as a test reaction for the comparison of different reactors. A metal microchannel reactor reveals a behaviour that indicates a better isothermicity than a laboratory-scale tubular reactor. However, the blank activity of the stainless steel microchannels with their high surface-to-volume ratio seems to decrease the catalytic performance. A ceramic microchannel reactor has an intermediate isothermicity and less blank activity. From the experiments, additional features like pressure drop or mass transfer can be evaluated. The generic differences between microchannel reactors and conventional laboratory-scale reactors are discussed in the framework of recent literature. It becomes obvious that microchannel reactors may currently still suffer from problems like high blank activity or intricate catalyst application, but do have intrinsic advantages like the high isothermicity. On a general note, the different scaling of length, surface area and volume makes a straightforward comparison between microchannel reactors and conventional reactors far from trivial.

A new approach to the kinetic modeling of the reaction of gaseous HCl with solid lime at low temperatures

The chemical reaction between gaseous HCl and solid Ca(OH) 2 has several applications, namely in the dry scrubbing of acid gases. The behavior of this reacting system in a laboratory-scale tubular reactor was simulated using the ‘grain model’ for the solid phase and a cascade of CSTRs for the gaseous phase. This model was applied to experimental data obtained in a previous study, at low temperatures (50–130°C) and high humidity level. The results show that the diffusion of the gaseous reactant through the product solid layer is the rate-limiting step for this reaction. In the first reacting moments, when no solid product has yet been formed, the reaction is limited by the total consumption of the gaseous reactant, indicating a very fast chemical reaction (k s>10 −3 ms −1) . These results were compared with those obtained by two other models used to describe the behavior of the gaseous phase: the ‘differential reactor model’ and the ‘average concentration model’. We show that the differential reactor model, which has been largely applied in published works about this and other similar reacting systems, is not adequate for modeling the reaction process, particularly in its initial phase.

Fluid catalytic cracking: modelling of an industrial riser

The functioning of the riser of catalytic cracking units was simulated using a new kinetic model of the reactions and an accurate description of gas and catalyst hydrodynamics in the riser section. The kinetic model is based on a molecular description of cracking and hydrogen transfer reactions. It may be seen as an intermediate model between simple lumping of cuts and the ‘single events’ method. Chemical lumps, such as alkanes, alkenes, cycloalkanes, alkenic cycloalkanes and aromatics, are defined in different cuts. Kinetic constants are determined from experimental results obtained in a laboratory scale tubular reactor (M.A.T). The data on gas and solid flow in the riser are assessed by various experimental techniques: isokinetic sampling, Pitot probe, γ-ray tomography and tracing in a cold set-up or in industrial risers. The model results were compared with industrial yields.

Characterization of tars and coke formed during the pyrolysis of methane in a tubular reactor

Coke and tar formed during pyrolysis of methane in the thermal coupling regime have been characterized. The pyrolysis was performed in a laboratory scale tubular reactor at 1423–1473 K, with Ar or H 2 as diluent gases. Coke and soot samples were recovered from the reactor wall and from the quenching system, while tar was recovered from the quencher. The C H -ratio of the samples increased in the order tar < soot < coke flakes. The tar was analyzed by capillary gas chromatography and was found to contain polycyclic aromatic hydrocarbons of varying molecular weight. Solid samples were examined by scanning electron microscopy. The soot samples showed a fine structure consisting of small particles 1 μm in diameter. The coke recovered from the reactor wall had a cobblestone-like structure, with “cobbles ” 5–30 μm in diameter, indicating it was formed via liquid drops adhering to the surface. The solid samples were oxidized with O 2 in a microbalance. There were no systematic variations in reactivity between the samples. The activation energy of oxidation was found to be 60–110 kJ/mole, indicating a possible diffusion control of the reaction rate.

Zur Pyrolyse von 3‐Ethylpent‐2‐en – Ein weiterer Hinweis auf eine Homoallyl‐Umlagerung

Pyrolysis of 3‐Ethylpent‐2‐ene — a Further Evidence for a Homoallylic‐RearrangementThe pyrolysis of 3‐ethylpent‐2‐ene has been studied under conditions of steam cracking in the temperature range 600—700°C in a laboratory scale tubular reactor. The main products of decomposition were methane, 2‐ethylbutadiene and isoprene. The majority of products obviously arose from H abstraction and radical addition, typical for radical chain reactions in olefins decomposition including phenomena resulting from allylic resonance. The formation of isoprene, however, could only be explained by a reaction network including a homoallylic rearrangement.

High activity copper catalyst for one‐step conversion of methanol to methyl formate at low temperature

AbstractDehydrogenation of methanol on copper catalysts supported on SiO2 and modified by Cr2O3 was studied in the temperature range of 200 to 270°C. The chief product of reaction was methyl formate together with carbon monoxide and traces of formaldehyde.It was found that very high and sustained activity could be achieved by the method adopted for preparation of the catalysts. The unused catalyst was completely amorphous, but in catalyst samples used for long periods of time the presence of crystallites in the size range 50 to 65 Å was observed.Nearly 80% of theoretically obtainable conversion of methanol to methyl formate was achieved in laboratory scale tubular reactor. A catalyst containing Cu:Cr2O3:SiO2 = 5.0:5.90:7.0 prepared by the method described proved to be very active at low temperatures, giving 41% conversion to methyl formate at 230°C for long periods of use. No interaction between the active component and the support was noticeable.Addition of chromia improved the catalyst texture and stability. When nickel was present in quantities less than 1.25%, it acted as a promoter and gave improved performance.

Über die Thermische Umsetzung von Mono‐n‐alkylbenzenen

Thermal Reaction of Mono‐n‐alkyl‐benzenesThe pyrolysis of ethyl‐(1), n‐propyl‐(2), n‐hexyl‐(3) and n‐octylbenzene (4) has been studied under conditions of steam cracking (600 to 800°C) in a laboratory scale tubular reactor. The overall activation energies determined for (1) to (4) were found to be nearly identical (221 to 227 kJ · mol−1) obviously caused by similar initial steps. The main liquid product observed was styren accompanied by ω‐phenyl‐1‐alkenes and α‐olefins. Benzene is an important side product of 1. It might be formed mainly by a hydrogen assisted dealkylation via a cyclohexadienyl type radical as reactive intermediate.