Sweep Gas Flow Rate Research Articles

Fixed-bed catalytic pyrolysis of empty fruit bunch biomass for bio-oil

An attempt to the global clarion call to explore for an alternative source of environmentally friendly, renewable and cheaper energy (fuel) source than the conventional fossil fuel, was made in this study. This involved testing the effects of three catalysts (potassium carbonate K2CO3, calcium hydroxide Ca(OH)2 and magnesium oxide MgO) in the empty fruit bunch (EFB) pyrolysis on the product yields. The Ca(OH)2 catalyzed EFB pyrolysis gave the maximum percentage yield (42.64%) of bio-oil. The maximum bio-oil percentage yield from the Ca(OH)2 catalyzed EFB pyrolysis was obtained at pyrolysis temperature of 600°C, sweeping gas flow rate of 200mL/min and using 10wt.% of the catalyst. The GC-MS analysis of the Ca(OH)2 catalyzed EFB pyrolysis showed an increase (10.68%) in the desirable phenolic content and a reduction (35.21%) in the undesirable acidic components of the bio-oils when compared with the phenolic (16.74%) and acidic (42.88%) components of non catalyzed EFB pyrolysis bio-oil. This study has revealed that the quantity and quality of bio-oils can be improved using Ca(OH)2 catalyzed biomass pyrolysis.

Thermodynamic Analysis of Isothermal Redox Cycling of Ceria for Solar Fuel Production

A thermodynamic analysis of continuous fuel production by redox cycling of ceria in a single solar reactor under isothermal conditions is presented. Ceria is partially reduced in a sweep gas flow of purified nitrogen and reoxidized with either steam or carbon dioxide to produce hydrogen or carbon monoxide, respectively. The sweep gas and oxidizer flows are preheated by the product gases. The influence of selected process parameters, including operating temperature, pressure, and the effectiveness of heat recovery, on the solar-to-fuel conversion efficiency is determined. For a solar concentration ratio of 3000, typical of state-of-the-art solar dish concentrators, and operating temperature of 1773 K, 95.5% of the available gas-phase heat must be recovered to reach conversion efficiencies of 10% and 18% for hydrogen and carbon monoxide production, respectively, assuming the flow rate of inert sweep gas is equivalent to that in a counter-current flow arrangement of gas and ceria. The efficiency depends strongly on the gas-phase heat recovery effectiveness and the sweep gas flow rate. Introducing a temperature swing of 150 K between reduction and oxidation steps strongly reduces the sweep gas flow rate and increases the efficiency from 10% to 31.6% for hydrogen production.

Critical Analysis of Process Parameters for Bio-oil Production via Pyrolysis of Biomass: A Review

Pyrolysis is the destructive distillation of the biomass at high temperature in absence of oxygen. Depending upon the heating rate and residence time of vapors during the pyrolysis process, it is classified into slow and fast pyrolysis. Slow pyrolysis generally produces less amount of bio-oil and higher amount of charcoal than fast pyrolysis. This is attributed to the longer residence time for slow pyrolysis. A critical review on this subject has been elucidated in this article. It implies that the different constituents of biomass i.e. cellulose, hemicellulose and lignin are degraded at different temperature ranges. Moreover, the elemental composition of the initial biomass found to govern the bio-oil production such as C, H, N and O which are primarily dependent upon the types of waste materials. Thus, actual bio-oil production potential depends on feed materials, type of reactor, operating temperature, heating rate, volatile matter, carbon content, sweep gas flow rate and residence time. Bio-oil chemical compositions are also affected by the operating temperatures during the pyrolysis of biomass. The kinetic study of different biomass materials and methods applied to evaluate activation energy, accordingly, are also reviewed and listed. In this review article, a critical analysis of the factors upon which bio-oil production depends are emphasized with appropriate citation. It also covers an extensive literature review to ascertain the effect of operating parameters on pyrolysis of biomass. This article also focuses about the estimated waste biomass potential in India. Efforts are also made to highlight the estimated potential of biomass sources for bio-oil production in Indian perspective. An estimate shows that approximately 7% of petroleum crude oil can be compensated with the bio-oil if all the waste biomasses available in the country were properly used.

Production of ultrapure hydrogen in a Pd–Ag membrane reactor using noble metals supported on La–Si oxides. Heterogeneous modeling for the water gas shift reaction

Two different catalysts, Rh(0.6% wt/wt)/La2O3(27% wt/wt)·SiO2 and Pt(0.6% wt/wt)/La2O3(27%)·SiO2, were tested in the WGS reaction. Their performances were first studied in a conventional fixed-bed reactor. Their activities were similar and they were both very stable. However, as Pt(0.6)/La2O3(27)·SiO2 showed a much higher selectivity to the desired reaction, the performance of a membrane reactor employing this catalyst was studied. The effects of the H2O/CO ratio, space velocity, sweep gas flow rate and size of the catalyst particle on CO conversion and H2 recovery were studied at laboratory scale under isothermal conditions. A 1-D heterogeneous model was developed in order to properly reproduce the experimental results obtaining good agreement between the simulation results and laboratory data. The experimental and theoretical results confirm the existence of significant external mass-transfer limitations in the fluid-particle interface for these very active formulations.

Effect of binder burnout on the sealing performance of glass ceramics for solid oxide fuel cells

The glass ceramics composite sealants are among few materials suitable for the solid oxide fuel cells (SOFC) due to their high operating temperatures (600 °C–850 °C). The glass ceramics chemically bond to both the metallic interconnector and the ceramic electrolyte and provide a gas tight connection. A careful and several stages manufacturing procedure is required to obtain a gas tight sealing. In this study, effects of binder burnout process on the sealing performance are investigated employing commercially available glass ceramic powders. The glass ceramic laminates are produced by mixing glass ceramic powders with the organic binders and employing a tape casting method. The laminates are sandwiched between the metallic interconnectors of an SOFC cell. The burnout and subsequent sealing quality are analyzed by measuring leakage rate and final macrostructure of sealing region. The effects of heating rate, dead weight load, solid loading, carrier gas and their flow rates are investigated. It is found that sealing quality is affected from all investigated parameters. While a slower heating rate is required for a better burnout, the mass flow rate of sweep gas must be adequate for removal of the burned gas. The leakage rate is reduced to 0.1 ml min−1 with 2 °C min−1 + 1 °C min−1 heating rate, 86.25% solid loading, 200 N dead weight load and 500 ml min−1 sweep gas flow rate.

The Effects of Different Catalysts on the Pyrolysis of Thistle, Onopordum Acanthium L.

Fixed-bed fast pyrolysis experiments have been conducted on a sample of thistle, Onopordum Acanthium L. The experiments were performed in a fixed-bed tubular pyrolysis reactor to investigate the effects of sweeping gas flow rate and types of catalysts on the pyrolysis product yields. The optimal sweeping gas flow rate is 100 cm3 min−1. In order to increase the oil yield, biomass pyrolysis experiments were performed in a fixed bed reactor with two selected catalysts, namely sepiolite and clinoptilolite. All experiments were conducted in a nitrogen atmosphere with a heating rate of 300°C min−1, pyrolysis temperature of 550°C, and mean particle size of +0.6–0.85 mm. In the experiments, all the catalysts were used with various percentages, and the effects of the variable catalysts on the yields and chemical composition of the oils obtained were investigated. Oil yield reached 29.5% with the use of sepiolite and 32.1% with clinoptilolite, while it was only 18.9% without a catalyst. Chromatographic and spectroscopic studies on the pyrolytic oil showed that the oil obtained from thistle could be used as a renewable fuel and chemical feedstock.

Oxygen permeation and stability of Ba0.9Co0.7Fe0.2Nb0.1O3−δ membrane with three-layer structure

Oxygen permeation membrane with mixed ionic and electronic conductivities is a very attractive technology for the production of oxygen of high purity in an energy- and cost-efficient way. Recently, Ba0.9Co0.7Fe0.2Nb0.1O3−δ perovskite with A-site deficiency has drawn a lot of attentions for its high oxygen permeation flux and good stability. In this work, for further improving the oxygen permeation performance of Ba0.9Co0.7Fe0.2Nb0.1O3−δ membrane, a three-layer structure consisting of a dense thin film and two porous support layers is applied. The three-layer Ba0.9Co0.7Fe0.2Nb0.1O3−δ membrane achieved an oxygen permeation flux as high as 3.93mlcm−2min−1 at 900°C, which is nearly 1.5 times higher than that of the conventional membrane with the same overall thickness. By increasing the flow rate of sweep gas, the oxygen permeation flux of the three-layer membrane was further enhanced up to 4.85mlcm−2min−1. A short term stability test of 100h was conducted and no obvious degradation of the oxygen permeation performance was observed, which indicated that Ba0.9Co0.7Fe0.2Nb0.1O3−δ membrane with a three-layer structure could be very promising for the application in an oxygen generator.

Copper(I)-containing supported ionic liquid membranes for carbon monoxide/nitrogen separation

In this work, facilitated transport supported ionic liquid membranes (SILMs) were prepared with the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium chloride ([hmim][Cl]) and the cuprous chloride (CuCl) copper(I) salt to perform the selective separation of CO from N2. Previously, we reported that this solute-carrier system provides large CO/N2 solubility selectivity due to the reversible formation of a CO–copper(I) complex. The RTIL was impregnated in a porous PVDF membrane and pure and mixed gas permeation experiments were performed with continuous gas flow at constant pressure. The effects of different operating conditions were tested, namely pressure, temperature, sweep gas flow rate and liquid membrane composition. The CO permeability through the copper(I)-based SILMs increases with respect to pure [hmim][Cl]–SILMs owing to the CO carrier-mediated transport. On the contrary, the N2 flux is not affected, and therefore, the CO/N2 selectivity is increased. The CO transport through the reactive SILMs is enhanced at higher temperatures and copper(I) concentration. However, mixed gas experiments revealed a slight decrease of CO/N2 selectivity. Regarding membrane stability, SILMs were continuously operated for two weeks without any loss of performance. Additionally, gas diffusion coefficients (~10−10m2s−1) and solute-carrier complex diffusivity (~10–11m2s−1) were calculated in the RTIL media.

Bio-oil production through pyrolysis of blue-green algae blooms (BGAB): Product distribution and bio-oil characterization

Pyrolysis experiments of blue-green algae blooms (BGAB) were carried out in a fixed-bed reactor to determine the effects of pyrolysis temperature, particle size and sweep gas flow rate on pyrolysis product yields and bio-oil properties. The pyrolysis temperature, particle size and sweep gas flow rate were varied in the ranges of 300–700 °C, below 0.25–2.5 mm and 50–400 mL min−1, respectively. The maximum oil yield of 54.97% was obtained at a pyrolysis temperature of 500 °C, particle size below 0.25 mm and sweep gas flow rate of 100 mL min−1. The elemental analysis and calorific value of the oil were determined, and the chemical composition of the oil was investigated using gas chromatography–mass spectroscopy (GC–MS) technique. The analysis of bio-oil composition showed that bio-oil from BGAB could be a potential source of renewable fuel with a heating value of 31.9 MJ kg−1.

Conversion of Rice Straw to Bio-Fuel by Pyrolysis in Molten KCl-LiCl

The objective of this study was to provide background date on rice straw pyrolysis in molten KCl(40mol%)-LiCl(60mol%). The effects of pyrolysis temperatures and sweep gas flow rates on the pyrolysis products yields and their chemical compositions were studied. The temperatures of pyrolysis and sweep gas flow rates were varied in the range of 380°C -540°C and 60L/h-260L/h, respectively. The compositions of gaseous products were analyzed by gas chromatography, and that of bio-oil obtained was investigated using gas chromatography-mass spectroscopic(GC-MS) technique. The yield of gaseous products increases with the increasing temperature, the char yield has demonstrated a downtrend, and the maximum yield of bio-oil is up to 15.43 wt.% at 460°C. The yield of char decreases with the sweep flow rate, the gaseous has a minimum yield at 100L/h, and the maximum yield of bio-oil is 15.43wt.% at 100L/h .The main gaseous products are CO, CO2 , H2 and CH4. Ketones and phenols are the main compounds in the bio-oil, the presence of molten inhabites their formation, and promotes the production of furfural. The bio-oil attained from pyrolysis is a potential source of renewable fuel and chemical feedstock.

Catalytic Dehydrogenation of Methylcyclohexane (MCH) to Toluene in a Palladium/Alumina Hollow Fibre Membrane Reactor

A compact multifunctional Pd/alumina hollow fibre membrane reactor (HFMR) has been developed and used for the catalytic dehydrogenation of methylcyclohexane to toluene. The developed HFMR consists of a thin and defect-free Pd membrane of 5 μm coated directly onto the outer surface of an alumina hollow fibre substrate. The substrate, was prepared by a phase inversion/sintering method, possess a unique asymmetric structure which can be characterised by a very porous inner surface from which finger-like voids extend across approximately 80% of the fibre cross-section with the remaining 20% consisting of a denser sponge-like outer layer. A 50 wt% Ni/Al2O3 catalyst is directly deposited into the asymmetric support, with a fraction of catalyst particles distributed uniformly in the finger-like macro-voids while the others on the lumen surface forming a “filter-cake”-like layer. A significant increase in gas permeation resistance occurs due to this “filter-cake”-like catalyst layer when the catalyst loading (weight per unit fibre length) is above 2.3 mgcm-1. Methylcyclohexane conversion increases with the increasing temperatures, because of the endothermic nature of the reaction; while decreases with the higher sweep gas flow rates due to the more serious catalyst deactivation in the HFMR. For a HFMR with 1.0 mg cm-1 of catalyst loading, methylcyclohexane conversion of approximately 26% can be achieved at 610 °C with the sweep gas flowrate of 20 ml min-1, while for a porous membrane reactor and a fixed-bed reactor the methylcyclohexane conversion of 50% and 25% can be achieved at identical operating temperature.

B-site La-doped BaFe0.95−xLaxZr0.05O3−δperovskite-type membranes for oxygen separation

Partial La-substitution for Fe on the B-site of the perovskite BaFe0.95−xLaxZr0.05O3−δ (BFLZ) was achieved by applying a sol–gel synthesis method. The highest La content in BFLZ for the formation of a pure cubic perovskite structure without any detectable impurities is about x = 0.04. It is found for the first time that the introduction of La on the B-site of a mixed oxide stabilizes the cubic structure. Furthermore, the formation of the cubic structure of BFLZ increases significantly the oxygen permeability. The maximum oxygen permeation flux is found for a La-content of x = 0.04 with the largest volume of the cubic unit cell, reaching 0.63 and 1.24 cm3 (STP) min−1 cm−2 for a 1.1 mm thick membrane at 750 and 950 °C, respectively. This finding is in complete agreement with the XRD structure analysis, showing that the highest B-site La-substitution of BFLZ under conservation of the pure cubic perovskite phase without forming any foreign phase was about x = 0.04. For BFLZ with x > 0.04, the secondary phase Ba6La2Fe4O15 forms increasingly and the oxygen permeation flux decreases. The influence of the sweep gas flow rates on the oxygen permeation flux and the oxygen ionic conductivity were found to be in good agreement with the Wagner theory, indicating the oxygen ion bulk diffusion as a rate-limiting step of oxygen transport. Stable oxygen permeation fluxes were obtained during the long-term oxygen permeation operation of the BFLZ (x = 0.04) membrane over 170 h at 750 and 950 °C, respectively.

Parametric study of membrane reactors for hydrogen production via high-temperature water gas shift reaction

This study presents numerical studies of hydrogen production performance via water gas shift reaction in membrane reactor. The pre-exponential factor in describing the hydrogen permeation flux is used as the main parameter to account for the membrane permeance variation. The operating pressure, temperature and H2O/CO molar ratio are chosen in the 1–20 atm, 400–600 °C and 1–3 ranges, respectively. Based on the numerical simulation results three distinct CO conversion regimes exist based on the pre-exponential factor value. For low pre-exponential factors corresponding to low membrane permeance, the CO conversion approaches to that obtained from a conventional reactor without hydrogen removal. For high pre-exponential factor, high CO conversion and H2 recovery with constant values can be obtained. For intermediate pre-exponential factor range both CO conversion and H2 recovery vary linearly with the pre-exponential factor. In the high membrane permeation case CO conversion and H2 recovery approach limiting values as the operating pressure increases. Increasing the H2O/CO molar ratio results in an increase in CO conversion but decrease in H2 recovery due to hydrogen permeation driving force reduction. As the feed rate increases in the reaction side both the CO conversion and hydrogen recovery decrease because of decreased reactant residence time. The sweep gas flow rate has a significant effect on hydrogen recovery. Low sweep gas flow rate results in low CO conversion H2 recovery while limiting CO conversion and hydrogen recovery can be reached for the high membrane permeance and high sweep gas flow rate cases.

Interactions between oxygen permeation and homogeneous-phase fuel conversion on the sweep side of an ion transport membrane

The interactions between oxygen permeation and homogeneous fuel oxidation reactions on the sweep side of an ion transport membrane (ITM) are examined using a comprehensive model, which couples the dependency of the oxygen permeation rate on the membrane surface conditions and detailed chemistry and transport in the vicinity of the membrane. We assume that the membrane surface is not catalytic to hydrocarbon or syngas oxidation. Results show that increasing the sweep gas inlet temperature and fuel concentration enhances oxygen permeation substantially. This is accomplished through promoting oxidation reactions (oxygen consumption) and the transport of the products and reaction heat towards the membrane, which lowers the oxygen concentration and increases the gas temperature near the membrane. Faster reactions at higher fuel concentration and higher inlet gas temperature support substantial fuel conversion and lead to a higher oxygen permeation flux without the contribution of surface catalytic activity. Beyond a certain maximum in the fuel concentration, extensive heat loss to the membrane (and feed side) reduces the oxidation kinetic rates and limits oxygen permeation as the reaction front reaches the membrane. The sweep gas flow rate and channel height have moderate impacts on oxygen permeation and fuel conversion due to the residence time requirements for the chemical reactions and the location of the reaction zone relative to the membrane surface.

Ammonia removal from aqueous solution by membrane distillation

AbstractEnvironmental regulation, increased pressure on water resources and rising cost for wastewater discharges make wastewater treatment for recycling an essential investment for many industries. Ammonia is a major pollutant in many industrial and agricultural wastewaters, and its elimination is essential for wastewater to be reused or meeting local discharge standards. In this study, the removal of ammonia from dilute aqueous solution has been investigated using sweep gas and vacuum membrane distillation (SGMD and VMD). Factors that affect the separation process such as feed and air flow rates, vacuum degree and feed temperature have been investigated. Overall, mass transfer coefficients (Kov) were calculated, and the results indicated that Kov for VMD is higher than that for SGMD under similar operation. Overall, ammonia mass transfer coefficient up to 12.06 × 10−5 and 5.63 × 10−5 m/s can be achieved for VMD and SGMD, respectively. The ammonia removal efficiency was enhanced by increasing sweep gas flow rate or by decreasing downstream pressure.

Respiratory dialysis with an active-mixing extracorporeal carbon dioxide removal system in a chronic sheep study

PurposeThe objective of this study was to demonstrate the safety and performance of a unique extracorporeal carbon dioxide removal system (Hemolung, ALung Technologies, Pittsburgh, PA) which incorporates active mixing to improve gas exchange efficiency, reduce exposure of blood to the circuit, and provide partial respiratory support at dialysis-like settings.MethodsAn animal study was conducted using eight domestic crossbred sheep, 6–18 months of age and 49–115 kg in weight. The sheep were sedated and intubated, and a 15.5-Fr dual lumen catheter was inserted into the right jugular vein. The catheter was connected to the extracorporeal circuit primed with heparinized saline, and flow immediately initiated. The animals were then awakened and encouraged to stand. The animals were supported in a stanchion and monitored around the clock. Anticoagulation was maintained with heparin to achieve an aPTT of 46–70 s.ResultsMeasurements included blood flow rate through the device, carbon dioxide exchange rate, pump speed and sweep gas flow rate. Safety and biocompatibility measurements included but were not limited to plasma-free hemoglobin, hematocrit, white blood cell count, platelet count and fibrinogen. The Hemolung removed clinically significant amounts of carbon dioxide, more than 50 ml/min, at low blood flows of 350–450 ml/min, with minimal adverse effects.ConclusionsThe results of 8-day trials in awake and standing sheep supported by the Hemolung demonstrated that this device can consistently achieve clinically relevant levels of carbon dioxide removal without failure and without significant risk of adverse reactions.

An experimental study on bio-oil production from co-pyrolysis with potato skin and high-density polyethylene (HDPE)

In order to investigate the synergistic effect of high dense polyethylene (HDPE) addition to potato skin (pS) during co-pyrolysis, pure HDPE was pyrolysed as a model compound for determination of the optimum process conditions. Thermal decomposition of pure HDPE was performed at constant heating rate of 5°Cmin−1 under various pyrolysis temperatures (400, 420, 450, 470, 500 and 550°C) and sweeping gas flow rates (100, 200, 400 and 800cm3min−1). The maximum bio-oil yield was 56% at 500°C under sweeping flow rate of 400cm3min−1. Then, co-pyrolysis of pure HDPE-pS and waste HDPE-pS mixtures were pyrolysed with various proportions such as 1:0, 1:1, 1:2, 2:1 and 0:1. The yield of liquids produced during co-pyrolysis enhanced with increasing weight ratio of HDPE in mixtures. Obtained bio-oils were analyzed in detail with various spectroscopic and chromatographic methods. Co-pyrolysis oil had higher carbon and hydrogen contents, lower oxygen contents with higher heating value than those of pyrolysis. It was concluded that addition of HDPE improved the liquid yields in terms of both quality and quantity.

Ionic conducting ceramic and carbonate dual phase membranes for carbon dioxide separation

Abstract A dense membrane consisting of two-phases: molten carbonate for the conduction of carbonate ions and Bi 1.5 Y 0.3 Sm 0.2 O 3 (BYS) for the conduction of oxygen ions, was synthesized and used for selective permeation of CO 2 at high temperatures. Since CO 2 is transported by CO 3 2− , these membranes provide infinite selectivity for CO 2 over other species such as Ar, He or N 2 .The dual-phase membranes were synthesized by the direct infiltration molten carbonate into porous BYS supports with internal surface modified with γ-Al 2 O 3 to improve the wettability. Permeation took a long time to reach a steady state at the initial stage of high temperature CO 2 separation due to the reversible phase transform of the oxygen ions conduction phase between the rhombohedral structure and cubic fluorite structure. The CO 2 permeation flux for the dual phase membrane increases with increasing temperature (500–650 °C) with apparent activation energy for CO 2 permeation of 113.4 kJ/mol. The CO 2 permeation flux increases with increasing sweep gas flow rate and reaches a value of 0.083 mL/cm 2 /min at 650 °C and helium flow rate of 125 mL (STP)/min. The BYS–carbonate membrane offers higher CO 2 permeance than carbonate dual-phase membranes with lithium–cobaltite or yttrium stabilized zirconia as the oxygen ionic conducting phase.

Hydrogen-selective zeolite membrane reactor for low temperature water gas shift reaction

Hydrogen-selective zeolite membranes loading with CuO/ZnO/Al2O3 commercial catalysts were employed for low-temperature water gas shift (LT-WGS) reaction. The membranes were prepared by modifying zeolitic pores of MFI zeolite membranes with catalytic cracking deposition of methyldiethoxysilane. The membranes were tested by the separation of H2/CO2 mixture, which showed a high H2/CO2 separation factor of 42.6 with H2 permeance of 2.82×10−7mol/m2sPa at 500°C. Both the packed-bed and membrane reactors for LT-WGS were investigated by variation of temperature (T), space velocity (GHSV), steam-to-CO feed ratio (RH2O/CO) and sweep gas flow rate (FN2). Significant increment in CO conversion for the membrane reactor was achieved at relatively low temperature, high space velocity and low steam-to-CO ratio due to the large deviation from equilibrium state. High CO conversion of 95.4% was achieved in membrane reactor under the operation conditions (T=300°C, GHSV=1500LN/kgcath, RH2O/CO=1.25 and FN2=20cm3(STP)/min), which was higher than the equilibrium conversion. These results indicated that the membrane reactor had better performance for LT-WGS in eliminating CO.

Dehydration of natural gas using membranes. Part I: Composite membranes

All natural gas must be dried before it enters distribution pipelines, to control corrosion and prevent formation of solid hydrocarbon/water hydrates. Glycol dehydrators are often used for natural gas dehydration, which, however, causes the emissions of hazardous volatile organic compounds (VOCs). In light of increasing concerns about VOC emissions, this study examines the technical feasibility of membrane technology for natural gas dehydration. More specifically, the Part I of this study is focused on the laboratory-scale tests of composite membranes. First, the current state-of-the-art research in membrane materials for H2O/CH4 separation is reviewed. Hydrophilic microphase-separated block copolymers (Pebax®) with promising H2O/CH4 separation properties were identified and made into industrial thin film composite membranes. Second, the composite membranes were extensively tested in a laboratory permeation cell by varying operating parameters including feed gas composition, feed gas flow rate and the flow rate of the dry sweep gas on the permeate. Water vapor permeation was mainly restricted by the microporous support and paper layers of the composite membranes, as opposed to methane permeation, in which the main transport resistance was in the selective layer. Increasing sweep gas flow rate on the permeate side of the membrane decreased the overall membrane transport resistance to water vapor, thus increasing water vapor permeance (up to 2000 gpu) and H2O/CH4 selectivity (up to 1500). Finally, the effect of different layers of composite membranes on water vapor permeance and water/methane selectivity is interpreted using a resistance-in-series model. The Part II of this study will describe a field test of Pebax®-based membranes at a natural gas processing plant and membrane process designs to maximize the membrane separation efficiency.