Complete Oxygen Consumption Research Articles

A Numerical Study on the Ignition and Flame Propagation for Locally Stratified Methanol/n-Heptane Dual-Fuel Mixtures

ABSTRACT Flame propagation under thermal and compositional stratifications is relevant to a wide range of applications in combustion devices. In this work, numerical studies are conducted to investigate the multi-stage ignition process and flame propagation in the stratified methanol/n-heptane-air dual-fuel mixture under engine-like conditions. Firstly, the effects of the initial gas temperature of the oxidizer (TOX) and fuel stream on the ignition process and combustion modes are investigated. The results show that TOX affects the early-stage ignition, and a fuel-rich stabilization mode is observed at low temperatures. For example, at 800 K, both cool and hot flames are initiated at the regions close to the most reactive mixture fraction, . A transition from the fuel-lean to fuel-rich and then back to the fuel-lean regions in the mixture fraction space is observed at higher temperatures. Then, hot flames propagate into the methanol/air premixture, forming quasi-steady hot-flame fronts in the fuel-rich regions at TOX = 800 and 900 K owing to the lack of oxygen and low adiabatic flame temperatures. At 1000 K, another flame front propagates into the n-heptane/air mixtures owing to enhanced reaction rate at higher local temperatures. By increasing TOX, a balance owing to the gas expansion is observed at 1020 K, and a spontaneous ignition mode appears at temperatures above 1050 K owing to the high reactivity and early ignition of the methanol/air premixture. Secondly, the effect of compositional stratification on the ignition and flame structures is investigated. Compared with the double flame structure under thermal and compositional stratification conditions, only a single flame structure is observed for those cases with uniform temperatures. A high temperature in the fuel stream region accelerates the decomposition of n-heptane, resulting in the complete consumption of oxygen.

Assessment of the current ecological condition of the Kakhovka reservoir

Quality assessment and analysis of a current state of natural waters, especially when it comes to reservoir waters, is a very important stage in the organization of safe drinking water supply for human life and health. The purpose of this study is to assess a current ecological state of the Kakhovka reservoir in the Dnipropetrovsk region for the period 2016–2018. The object of the study is the natural waters of the reservoir. The subject of the study is a current ecological state of the waters of the Kakhovka reservoirs within the Dnipropetrovsk region. Research methods are based on comparative-geographical, statistical, zoning and other research methods. In addition the work used: A graphic method for an integrated assessment of a surface water quality; A method for assessing the water quality in the water bodies by hydrochemical parameters. According to the results of the study of a current state of the Kakhovka reservoir waters within the Dnipropetrovsk region for the period 2016–2018, it was found that among the nine water quality indicators the priority indicators are: chemical oxygen consumption (COC) and biological complete oxygen consumption (BOcC). In most cases, these indicators were observed to exceed the limited permissible concentrations (LPC). High values of the COC indicator are a consequence of this water pollution with sewage; and high values of the BOcC index indicate a significant organic content that decomposes in the water. As a result of the analysis of the dynamics of changes in the total indicators of the LPC multiplicity, a stable improvement in the water conditions of the Kakhovka reservoir occurs in section № 4, and for other observation points an improvement in the water condition is observed in 2017 compared to 2016, and in 2018 compared to 2017 there is a deterioration in the state of natural waters.

Changes of CO2 Concentration and Heat Illustrate Why the Flame Is Extinguished in the Candle-and-Cylinder Experiment

The extinguishment of the candle flame in the well-known candle-and-cylinder experiment has been erroneously viewed as caused by the complete consumption of oxygen, for many reasons. To address thi...

The role of homogeneous steam reforming of acetylene in the partial oxidation of methane to syngas in matrix type converters

The conversion of natural gas to syngas is a key and most expensive stage of modern gas chemical technologies. As a promising alternative to existing technologies, a non-catalytic matrix conversion of natural gas to syngas was proposed. However, the reaction products, in addition to CO and H2, also contain unreacted methane, CO2 and acetylene. The latter is the most problem impurity, as it is a precursor of soot and other heavy products. In this work, the kinetic analysis of changes in the composition of the products during the matrix conversion of rich methane-air mixtures up to the establishment of the thermodynamic equilibrium was carried out. Three characteristic stages of the process were identified. The first stage of fast reactions involving oxygen is completed in a very short time (∼10−2 s at 1500 K) with almost complete oxygen consumption and the formation of CO, H2, CO2, H2O and some minor products of methane pyrolysis, mainly acetylene, but at their ratio, far from equilibrium. At the second stage, slow reactions of steam reforming of the formed products significantly increase the amount of hydrogen. The ratio [CO2][H2][CO][H2O] reaches an equilibrium value, but not the concentration of individual products due to incomplete conversion of acetylene and methane. At the third and longest stage, the system reaches equilibrium, and acetylene is not among the equilibrium products. The results of kinetic modeling and experimental study of partial oxidation of methane in matrix-type reformers have shown the important role of acetylene steam conversion in the post-flame zone. This reaction leads to a substantial decrease of methane and acetylene with a simultaneous increase in the yields of hydrogen and CO.

Searching for an absolute kinetic scale of antioxidant activity against lipid peroxidation

The inhibition properties of a number of antioxidants against peroxidation, started by a 2,2′-azobis[2-(2-imidazolin-2-yl)propane] radical initiator, of linoleic acid in sodium dodecyl sulfate micelles, have been determined in terms of oxygen consumption by a Clark electrode in an oxygen-tight cell. For the 31 antioxidants investigated at variable concentrations, the experimental results well fit the kinetic equation for competitive reactions.The ratio between the initial rates, monitored in the absence and in the presence of antioxidants, depends linearly on their concentration. From the slopes of these straight lines, an absolute scale of inhibition properties of the lipid peroxidation can be devised. Furthermore, the little difference of the time of complete oxygen consumption on concentration of different antioxidants has been found, indicating a restricted difference towards chemical structure and stoichiometric ratio.Some considerations regarding the mechanisms of inhibition of the lipid peroxidation in micelles, in view of bibliographic data, have been made.

Impacts of Accumulated Particulate Organic Matter on Oxygen Consumption and Organic Micro-Pollutant Elimination in Bank Filtration and Soil Aquifer Treatment

Bank filtration (BF) and soil aquifer treatment (SAT) are efficient natural technologies in potable water reuse systems. The removal of many organic micro-pollutants (OMPs) depends on redox-conditions in the subsoil, especially on the availability of molecular oxygen. Due to microbial transformation of particulate and dissolved organic constituents, oxygen can be consumed within short flow distances and induce anoxic and anaerobic conditions. The effect of accumulated particulate organic carbon (POC) on the fate of OMPs in BF and SAT systems is not fully understood. Long-term column experiments with natural sediment cores from the bank of Lake Tegel and from a SAT basin were conducted to investigate the impact of accumulated POC on dissolved organic carbon (DOC) release, on oxygen consumption, on mobilization of iron and manganese, and on the elimination of the organic indicator OMPs. The cores were fed with aerated tap water spiked with OMPs to exclude external POC inputs. Complete oxygen consumption within the first infiltration decimeter in lake sediments caused mobilization of iron, manganese, and DOC. Redox-sensitive OMPs like diclofenac, sulfamethoxazole, formylaminoantipyrine, and gabapentin were eliminated by more than 50% in all sediment cores, but slightly higher residual concentrations were measured in effluents from lake sediments, indicating a negative impact of a high oxygen consumption on OMP removal.

Influence of temperature and stabilization on oxygen diffusion limited oxidation profiles of polyamide 6

The oxidative degradation behavior of polymers depends on a combination of chemical and physical factors, with oxygen diffusion being one of the most important, especially when the oxygen consumption rate is larger than its permeability.As a result of diffusion limited oxidation (DLO), at high temperatures the degradation rate of polyamide 6 (PA6) plaques is heterogeneous, with the polymer oxidizing much faster at the surface than in the bulk. Normalized carbonyl index (CI) and UV absorption – depth profiles were found to be mostly degradation time independent, implying equilibrium degradation conditions where oxygen permeability and reaction rates did not change significantly with degradation time. The experimental DLO profiles were described using a basic reactive-diffusion model based on Fickian oxygen diffusion and an oxidation rate being first order in local O2 concentration, as well as by applying an established DLO model based on the basic autoxidation mechanism. Analysis with the second model yielded the best estimation of high temperature oxygen permeability (PO2) data. It also showed some of the limitations in the data analysis when using a simple first order DLO model.It was shown that stabilizers have an influence on the oxidation - depth profiles. Better stabilization results in slower polymer oxidation and the oxidation – depth profiles are therefore less pronounced. At 170 °C it was observed that stabilized plaques (0.5 mm) in the center oxidize faster than unstabilized plaques, which is attributed to the complete consumption of oxygen in the outer layers for the unstabilized plaques. Oxidation rates of differently stabilized samples were also determined by applying the second DLO model.

Hydrogen, nitrogen and carbon dioxide production through chemical looping using iron-based oxygen carrier – A Green plant for H2 and N2 production

Abstract In order to simulate the performance of pure methane in chemical looping using iron-based oxygen carrier, simultaneously production of three pure streams of hydrogen, nitrogen and carbon dioxide has been investigated. For this purpose, proper operating conditions have been discussed for maximum production of hydrogen, complete consumption of oxygen of inlet air and complete combustion of methane. Professional software is used to simulate the chemical looping reactors and optimize their output streams. Results show that in this process each mole of methane fuel can produce 2.533, 2.65 and 0.99 mol of pure N2, H2 and CO2, respectively which contributes 80.2% energy conversion of CH4 to H2. Moreover, in order to consume the whole input fuel and maximize hydrogen production, it is necessary to use a supportive material to improve mechanical property of oxygen carrier particles and optimize temperature of streams by thermal integration of three reactors. Also, due to controllable temperature of three reactors, more flow rate of oxygen carrier particles can be used instead of supportive material while the air flow rate should be justified to produce pure nitrogen. Hence, three chemical looping reactors, beside hydrogen and CO2 production, can directly produce nitrogen, by means of a process simpler than the conventional technologies like air separation unit.

Centennial- to millennial-scale climate oscillations in the Central-Eastern Mediterranean Sea between 20,000 and 70,000 years ago: evidence from a high-resolution geochemical and micropaleontological record

Here we present a high-resolution faunal, floral and geochemical (stable isotopes and trace elements) record from the sediments of Ocean Drilling Program Site 963 (central Mediterranean basin), which shows centennial/millennial-scale resemblance to the high-northern latitude rapid temperature fluctuations documented in the Greenland ice cores between 20 and 70 kyr BP.Oxygen and carbon isotopes, planktic foraminifera and calcareous nannofossil distributions suggest that Dansgaard–Oeschger (D/O) and Heinrich events (HE) are distinctly expressed in the Mediterranean climate record. Moreover, recurrent though subdued oscillations not previously identified in the Lateglacial Mediterranean sediments document a significant centennial-scale climate variability in the basin that is greater than previously thought.Alternations between climate regimes dominated by polar outbreaks during D/O stadials and warm D/O interstadials, with associated intensification of continental runoff, are well expressed in the ODP Site 963. These place the Mediterranean basin as an often overlooked recorder of the interplay between large- and regional- scale climate controls at intermediate latitudes, and of the possible interactions between different components of the climate system. Significant changes in Ba/Ca values measured in Globigerinoides ruber shells from a number of D/O stadials and interstadials suggest enhanced freshwater input from the north-eastern Mediterranean borderland during the D/O interstadials. However, the short duration of 3D stratification events never led to complete oxygen consumption along the water column, but clear effects of sluggish 3D circulation in the basin are testified to by negative excursions in δ13C measured in selected species of planktic and benthic foraminifera.HEs are constantly associated with lightening in the δ18O record of planktic foraminifera, possibly because of the impact of iceberg melting in the Iberian Margin on Mediterranean thermohaline circulation. Interestingly, in two cases in particular, HE2 and HE5, fresher water inputs also affected deeper horizons of intermediate waters, suggesting a basin-wide impact.

Degradation of aqueous methyldiethanolamine by temperature and oxygen cycling

Abstract The primary degradation products identified in aqueous 7 molal (m) methyldiethanolamine (MDEA) loaded to 0.1 mol CO 2 /mol alkalinity and degraded in the Integrated Solvent Degradation Apparatus (ISDA) were diethanolamine (DEA), bicine and formate. DEA and bicine represented 43 and 9 % of the carbon loss, respectively, after the solvent was cycled for 167 hours. An MDEA loss of 8.8 mM/hr and a formate production of 0.6 mM/hr were measured when 7 m MDEA cycled from 55 to 120 °C in the ISDA in its initial design, which allowed bubble entrainment. When bubble entrainment was minimized through coalescence and removal, the MDEA loss and formate production were cut in half (4.6 mM/hr and 0.31 mM/hr). When dissolved oxygen was stripped from cycled MDEA with N 2 gas at 2 L/min, the MDEA loss was negligible, and the formate production was reduced to 0.05 mM/hr. Designers of CO 2 scrubbing systems for post-combustion capture should minimize dissolved and entrained oxygen carryover into the stripper. Stripping of entrained and dissolved oxygen before the stripper is recommended to avoid high temperature oxidation. An oxygen solubility limit exists at a thermal reactor temperature of 120 °C which can be expressed as an apparent upper limit of dissolved O 2 available to degrade ∼1.3 mM MDEA/pass. The oxidative degradation model compensates for the complete consumption of dissolved oxygen in the thermal reactor at higher temperatures (>100 °C). The model assumes that all oxidative degradation is occurring in the thermal reactor under plug-flow reactor (PFR) behavior, and compensates for complete oxygen consumption with a stoichiometric factor (S). The regressed values of S, E a , and k o for formate were 0.1, 107 kJ/mol, and 2.4 1/hr, respectively. The predicted rates of formate production approximately match the measured rates over the entire measured temperature range of 55 to 120 °C. Oxidation Inhibitor A is ineffective over the temperature range of 90 to 120 °C in cycled solvents

Modeling On-Grate MSW Incineration with Experimental Validation in a Batch Incinerator

This paper presents a 2-D steady-state model developed for simulating on-grate municipal solid waste incineration, termed GARBED-ss. Gas-solid reactions, gas flow through the porous waste particle bed, conductive, convective and radiative heat transfer, drying and pyrolysis of the feed, the emission of volatile species, combustion of the pyrolysis gases, the formation and oxidation of char and its gasification by water vapor and carbon dioxide, and the consequent reduction of the bed volume are described in the bed model. The kinetics of the pyrolysis of cellulosic and noncellulosic materials were experimentally derived from experimental measurements. The simulation results provide a deep insight into the various phenomena involved in incineration, e.g., the complete consumption of oxygen in a large zone of the bed and a consequent char-gasification zone. The model was successfully validated against experimental measurements in a laboratory batch reactor, using an adapted sister version in a transient regime.

Catalytic partial oxidation of CH 4 over Ni-substituted barium hexaaluminate catalysts

Ba 0.75Ni y Al 12− y O 19− δ ( y = 0.2, 0.4, 0.6, 0.8 and 1.0) catalysts were tested for the partial oxidation of CH 4 at temperatures between 200 and 900 °C. Temperature programmed reaction results indicate that light-off for the partial oxidation reaction occurred between 665 and 687 °C for all catalysts. Isothermal runs performed at 900 °C on the catalysts showed stable reaction product concentrations, consistent with equilibrium. Post-reaction analysis of the used catalysts showed that there are two distinct zones in the catalyst bed. In a short leading edge of the bed, the apparently complete consumption of oxygen leads to a catalyst which XANES analysis shows is primarily Ni-substituted into the hexaaluminate phase. In the downstream portion of the bed, Ni is shown to be present as metallic Ni. This corresponds to a reaction sequence in which the oxidation of CH 4 proceeds at the inlet until all oxygen is reacted, followed by the reaction of CO 2 and H 2O with unreacted CH 4, and its derivatives, to produce the final syngas mixture. From the change in the unit-cell dimensions with Ni substitution, there is a clear indication that Ni 2+, which has a larger ionic radius than aluminum, substitutes for Al 3+ in the hexaaluminate lattice in the synthesis process, and there is no restructuring of the bulk hexaaluminate phase after the Ni is removed from the lattice.

Induction and efficacy of immobilized laccase from Bacillus lichniformis for removal of phenolics in aqueous solution

were approximately 0.015 day −1 and 85%, respectively, observed in microcosms containing microbial inocula (mass ratio of soil to inocula = 50:1), nutrient, and bulking agent addition (volume ratio of soil to bulking agent = 10–1) during 155 days of incubation. The TPH decay rate and removal ratio were only 0.0069 day−1 and 45%, respectively, in microcosms under intrinsic conditions. TPH decay rate could be further enhanced to 0.0196 day −1 in microcosms with frequent soil shaking and air replacement. Results also indicate that a decay rate of 0.0142 day −1 can be obtained in microcosms with the addition of chicken manures. Thus, chicken manures have the potential to be used as substitutes of commercial microbial inocula. Results show that TPH removal trend leveled off after approximately 74–93 days of operation. This might be due to the effects that the remaining compounds or byproducts might be less biodegradable, which caused the decreased TPH removal efficiency. The decreased oxygen and increased carbon dioxide contents in the headspace of microcosms indicate the occurrence of aerobic biodegradation. Moreover, the increased total heterotrophs in the early stage and increased total anaerobes in the later stage of the microcosm study also confirmed the shift of aerobic biodegradation to anaerobic biodegradation pattern when complete oxygen consumption was observed after 23 days of operation. Results will be useful in designing an ex situ soil bioremediation systems (e.g., biopile, landfarming) for practical application.

Hydrogen production by partial oxidation of methanol over bimetallic Au–Ru/Fe2O3 catalysts

Abstract Hydrogen production by partial oxidation of methanol (POM) was investigated over Au–Ru/Fe 2 O 3 catalyst, prepared by deposition–precipitation. The activity of Au–Ru/Fe 2 O 3 catalyst was compared with bulk Fe 2 O 3 , Au/Fe 2 O 3 and Ru/Fe 2 O 3 catalysts. The reaction parameters, such as O 2 /CH 3 OH molar ratio, calcination temperature and reaction temperature were optimized. The catalysts were characterized by ICP, XRD, TEM and TPR analyses. The catalytic activity towards hydrogen formation is found to be higher over the bimetallic Au–Ru/Fe 2 O 3 catalyst compared to the monometallic Au/Fe 2 O 3 and Ru/Fe 2 O 3 catalysts. Bulk Fe 2 O 3 showed negligible activity towards hydrogen formation. The enhanced activity and stability of the bimetallic Au–Ru/Fe 2 O 3 catalyst has been explained in terms of strong metal–metal and metal–support interactions. The catalytic activity was found to depend on the partial pressure of oxygen, which also plays an important role in determining the product distribution. The catalytic behavior at various calcination temperatures suggests that chemical state of the support and particle size of Au and Ru plays an important role. The optimum calcination temperature for hydrogen selectivity is 673 K. The catalytic performance at various reaction temperatures, between 433 and 553 K shows that complete consumption of oxygen is observed at 493 K. Methanol conversion increases with rise in temperature and attains 100% at 523 K; hydrogen selectivity also increases with rise in temperature and reaches 92% at 553 K. The overall reactions involved are suggested as consecutive methanol combustion, partial oxidation, steam reforming and decomposition. CO produced by methanol decomposition is subsequently transformed into CO 2 by the water gas shift and CO oxidation reactions.

Selective methanation of carbon oxides in a microchannel reactor—Primary screening and impact of gas additives

Selective removal of CO by methanation of carbon oxides has been performed over wash-coated supported metal catalysts in a microchannel reactor with simulated reformate feeding. The primary screening over a series of Ru and Ni-based catalysts shows that methanation activity is markedly dependent on the type of metal, the metal loadings and the promoter. Ni/CaO/Al 2O 3 catalyst exhibits the highest methanation activity with CO conversion higher than 93% and a relatively low conversion of CO 2 into methane among investigated catalysts at 300 °C under the operating condition. The appropriate temperature for selective methanation was identified to be 250 °C below which CO methanation preferentially and exclusively occurs. The effect of reaction temperature and gas additives such as steam and gaseous oxygen on the methanation performance is presented in terms of catalytic activity, selectivity, and methane yield. The regulation of carbon oxides methanation on Ni/CaO/Al 2O 3 catalyst by gaseous oxygen was realized by a switchover of the reaction pathway from combustion reaction in the presence of gas phase oxygen to the methanation upon the complete consumption of oxygen and the dynamic behaviour of catalyst surface induced by the interplay of the catalyst surface and the gas phase reactants.

Similarities and dissimilarities in n-hexane and benzene sooting premixed flames

The flame structure of atmospheric-pressure sooting premixed flames of aliphatic and aromatic hydrocarbons with the same carbon atom number (hexane and benzene) were studied at similar temperatures and C/O ratios by sampling and chemical and spectroscopic analysis. The differences in the oxidation mechanism of hexane and benzene in fuel-rich conditions were found to produce a different chemical environment in the yield of light hydrocarbons and their relative compositions where soot inception occurs. The predominance of acetylene and simple aromatic reactants in the oxidation region of the benzene flame favoured the early appearance and steep rise of soot particles. Large formations of saturated and unsaturated hydrocarbons were observed in the main oxidation region of the hexane flame whereas a delayed formation of aromatics (mainly PAH) was observed at soot inception only after complete oxygen consumption. There are differences in soot inception mechanisms reflected by the soot structure from UV–vis spectral shapes and mass specific absorption coefficients. In the benzene flame, they appeared to be more ordered and aromatic with a narrower size of aromatic systems and/or more curved aromatic structures. By contrast, less ordering with a more complex aliphatic/aromatic structure and a larger variety of aromatic systems were found to characterize soot formed in the hexane flame.

Wave sequences for solid fuel adiabatic in-situ combustion in porous media

We study the Riemann problem with forward combustion due to injection of air into a porous medium containing solid fuel. We neglect air compressibility and heat loss to the rock formation. Given initial reservoir and injection conditions, we prove that there is a unique time asymptotic wave sequence for combustion with complete oxygen consumption. The sequence consists of a region of unburned air at injection temperature, a warming discontinuity, a hot region with unburned air, a combustion wave and a region with burned air and unburned fuel at the initial reservoir temperature. The waves have very different speeds, and therefore they cannot be detected in laboratory experiments that focus on the combustion wave. However, they should occur in field scale. By introducing a cut-off in Arrhenius' law, the reaction rate vanishes at reservoir temperature, and two types of wave sequences are possible. One was already described. The other occurs for incomplete oxygen consumption. In this case, the wave sequence contains another wave, i.e., there is another region ahead of the combustion wave containing incompletely burned air at reservoir temperature, and a gas composition discontinuity that moves fast. However, instead of a unique solution for each Riemann data, there is a one parameter family of wave speeds and strengths. This multiplicity of solutions may to be due to the cut-off.

Enhancing the Productivity of Isobutane Selective Oxidation Over a Mo–V–P–As–Cs–Cu–O Heteropoly Acid Catalyst

Ways of enhancing the productivity of isobutane selective oxidation over a Keggin-type heteropoly acid catalyst, Mo12V0.5P1.5As0.4Cu0.3Cs1.4Ox, have been studied. Productivity increased with increasing temperature and isobutane partial pressure, although was limited by the complete consumption of oxygen and the catalyst thermal stability. Productivity was higher at short contact times. Simultaneously raising the total pressure and the space velocity enhanced the productivity up to 6.4 mmol methacrolein+methacrylic acid/h/gcat, which would be acceptable for an industrial application of the process.

Air Injection LTO Process: An IOR Technique for Light-Oil Reservoirs

Summary The paper describes an air injection improved oil recovery (IOR) process for the recovery of residual oil from light-oil reservoirs. Unlike the air injection technique applied in heavy-oil reservoirs, the main concern for a light-oil reservoir is to remove the oxygen from the injected air by some kind of spontaneous reaction between the oil and oxygen. In-situ combustion in heavy oil reservoirs is a very effective reaction pathway to achieve complete oxygen consumption, as well as to generate heat for enhanced oil recovery. For deep light-oil reservoirs, in-situ combustion is not necessary and may not be readily sustained. More likely, so-called low temperature oxidation (LTO) will prevail. In this study, the potential for LTO reactions to consume oxygen, the reaction rate, and the reaction pathways are investigated. A simplified LTO reaction model has been established based on experimental data obtained from a batch reactor experiment. The model was validated against high-pressure flow displacement experiments in an oxidation tube. A scoping simulation study on a reservoir scale has enabled a sensitivity assessment of the process to be made. The effect of air injection rate, reservoir dip, oil viscosity, formation permeability, numerical grid size, and reservoir temperature on oil recovery and the thermal effect were investigated. Compared with what is normally understood to be conventional air injection (insitu combustion), the air injection LTO process is flexible in terms of injection rate, stable because of spontaneous reaction (if the reservoir temperature is high enough), and also an economic alternative to hydrocarbon, nitrogen, or carbon dioxide gas. It can also be used as a secondary recovery method in reservoirs that are not suitable for water injection.

Coupling of Consecutive Reactions in a Two-Layer, Flow-Through Catalytic Membrane

A flow-through catalytic membrane has been used to carry out consecutively the oxidative and non-oxidative dehydrogenation of butane, with the aim of achieving thermal and chemical coupling of both processes. To this end, two distinct zones were created across the membrane radius: the first, containing V supported on MgO, was prepared by sequential impregnation, and the second, containing Pt-Sn on γ-Al 2 O 3 , was prepared by sol-gel procedures. The investigation highlights some of the problems encountered during membrane preparation, which are discussed and related to the reaction results observed. When the preparation procedures are tailored to achieve segregation of the catalytic materials in both layers, and when the operating conditions are such that complete oxygen consumption within the oxidative dehydrogenation layer is obtained, the use of the flow-through, two-layer membrane allows stable operation and, at the same time, gives rise to increased conversion and selectivity.