•MATR for hydrogen production in traditional and membrane reactor are investigated experimentally.•The highest conversion is obtained at medium temperature in membrane reactor.•High methane conversion and hydrogen yield appear at the α = 1 and the β = 2.•The H2/CO mole ratio can be regulated by changing the steam/methane molar ratio.An experimental investigation was investigated in order to assess the performance of the methane auto-thermal reforming (MATR) for hydrogen production over a nickel catalyst on an alumina support in both a traditional reactor (TR) and a membrane reactor (MR). The results show that the property of the reformer is dependent on the reformer temperature, the feed flow rate, the purge gas flow rate and the mole ratio of air-methane and steam-methane. The performance of the membrane reactor is better than the traditional reactor. The optimum conditions for high methane conversion and high hydrogen yield are air-methane and steam-methane mole ratio of 1 and 2, respectively. Under these conditions, a methane conversion of 96.13%, a hydrogen yield of 70.43% and hydrogen permeation rate of 81.61% can be achieved. Experimental results in terms of methane conversion, hydrogen yield and hydrogen permeation rate were compared with the traditional reactor and literature data.

•A spiral multi-cylinder reactor is designed and the major influence factors are investigated in detail.•The 42 steps detailed elementary reaction mechanism is adopted in the numerical calculation.•The optimum conditions are obtained with oxygen-carbon ratio of 0.4 and water-carbon ratio of 2.1.•The total of carbon deposition is about 1.65 × 10−12 kmol/m2 and the methane conversion rate achieves 93–99%.Using a chemical reaction dynamics software of CHEMKIN and the CFD software, the influences of T, W/C, O/C and catalysts activity density on methane conversion, carbon deposition and the yields of H2, CO and CO2 are investigated in the reaction of autothermal reforming of methane in a micro-reactor. The results show that optimum conditions of methane autothermal reforming are the oxygen–carbon ratio of 0.4, the water-carbon ratio of 2.1, the temperature of 1073 K, the flow velocity of 1 m/s and the catalyst active site density of 9.98 × 10−6 kmol/m2. Under these conditions, the methane conversion rate, the yields of H2 and CO are 93–99%, 65–80% and 50–65%, respectively. The total carbon deposition is about 1.65 × 10−12 kmol/m2. Moreover, the investigation and development of the three-dimensional spiral multi-cylinder micro-reactor are essential for applications of the mobile fuel cell in the Micro-Electro-Mechanical Systems (MEMS) field.

SO2 emissions to the atmosphere result in acid rain, which is a key issue for the environment. Membrane gas absorption is a novel approach to minimize the SO2 emissions to the atmosphere. A comprehensive mass transfer model considering the nonwetting mode is proposed to observe the SO2 absorption performance. A physical solvent of H2O and a chemical solvent of N,N-dimethylaniline are utilized as the aqueous absorbents. The calculated results are verified against the available experimental data derived from two different modules, demonstrating a good consistency. The effects of the inside membrane diameter, membrane thickness, porosity, fiber length, number of fibers, and inside module diameter on removal of SO2 were simulated. The results show that an improvement in the absorption performance can be achieved by increasing the number of fibers and porosity, and decreasing the membrane thickness and inner contactor radius. Furthermore, a longer module length (corresponding to a higher gas–liquid contact area) results in a sharp decline of the SO2 removal efficiency, while the SO2 flux increases. Finally, the model provides guidelines for the selection of optimum module parameters for SO2 absorption.

•Combustion characteristics of micro-combustor with baffles was simulated.•A higher baffle length improves methane conversion rate significantly.•A higher baffle length leads methane conversion speed to decrease obviously.•The temperature distribution of premixed zone becomes more uniform when θ = 2°.•The baffle angle can significantly influence the distribution of flow velocity field.This paper researches on premixed combustion of a methane/air mixture in a heat recuperation micro-combustor with corundum material, in terms of combustion characteristics of CH4/air in micro channel with Rh catalyst. 3D model is used with the detailed surface elementary reaction mechanism, and analyzes the influence of the baffle length, baffle angle θ, inlet temperature and inlet velocity on the methane conversion rate and heat transfer effect in heat recuperation micro-combustor with plate structure. The results show that an increase of baffle length can increase methane conversion rate and average temperature of burner, but it reduces methane conversion speed, and the maximum value of methane conversion speed is found to shift toward the entrance of reaction zone. It is obvious that θ = 2° can increase the area of high temperature distribution zone, meanwhile, the temperature distribution becomes more and more uniform, but the maximum value of temperature is lower than the others in any one inlet temperature conditions, and the value is merely 1350 K. The research indicates that the baffle angle θ of burner can significantly influence the distribution of flow velocity field, and further effect on the distribution of temperature field.

Membrane absorption is a novel method for acid gas removal compared to conventional separation techniques. The current study presents the simulation results using a computational fluid dynamics (CFD) method for biogas purification. A comprehensive two-dimensional (2D) mass-transfer model was developed and solved in a hollow fiber membrane contactor (HFMC) under a non-wetted condition. H2O, triethanolamine (TEA), diethanolamine (DEA), monoethamolamine (MEA), and potassium argininate (PA) were used as the absorbent liquids. The effects of gas–liquid parameters and membrane characteristics on the CO2 removal efficiency and absorption flux and CH4 recovery were systematically examined and evaluated. The comparisons between model predictions and experimental data with various gas–liquid parameters were in good agreement. An increase of gas velocity and CO2 content caused an increase of CO2 flux and a decrease of CO2 removal efficiency and CH4 recovery; however, an increase of absorbent velocity and concentration caused an increase in the above three values. In addition, a smaller fiber inner diameter and membrane thickness and a longer module were good for the biogas upgrading process. It should be noted that the highest CO2 flux coincided with the original module dimensions. The simulation predictions also showed that PA provided better membrane module performance than other absorbents. The order for CO2 absorption efficiency and CH4 recovery was PA > MEA > DEA > TEA > H2O. Overall, the developed model provides the guidelines for selecting the optimum module properties and fluid conditions. The membrane gas absorption technique has shown great potential in biogas upgrading.

Biogas upgrading and utilization is a novel technology to obtain resource-efficient vehicle fuel. In this study, a mass transfer model for CO2 absorption from biogas into potassium argininate (PA) solutions was developed. The computational fluid dynamics (CFD) methods were employed to solve the differential equations in three domains of the membrane contactor. The simulations were focused on the characteristics of both gas and absorbent phases to demonstrate the concentration distributions in axial and radial directions in the module. The simulated results were in excellent agreement with experimental data when considering the effect of initial CO2 concentration and gas velocity. Furthermore, the effect of operating pressure, flow pattern, flow condition, and modules in series on the membrane performance was investigated. The results showed the purity of CH4 reached 95% with the operating pressure of 0.9 MPa. It was found that a fluid in the turbulent condition or counter-current configuration had a significant effect on improving the contactor performance. The simulation results also indicated that the use of two modules could increase CO2 removal and obtain high CH4 purity. Finally, the results confirmed that the developed 2D model was able to predict the behavior of CO2 separation in the membrane contactors.

•Combustion characteristics of hydrogen addition on fuel were simulated.•Addition of hydrogen promotes the chemical reaction of methane combustion.•CO and CO2 emissions decrease when the hydrogen addition fraction increases.•Hydrogen addition makes ignition time advance and ignition temperature reduce.•Combustion stability is improved as hydrogen addition fraction increases.Understanding of micro-scale combustion mechanism is very essential to the development of micro-power devices, so hydrogen assisted catalytic combustion of methane on platinum was studied in this paper. The combustion of preheated mixtures of methane-hydrogen-air in a micro-combustor was modeled by a two-dimensional model including an elementary-step surface reaction mechanism. It was demonstrated that the model could predict the effects of changes of hydrogen fraction. It was shown that the mole fraction of H, OH and C(s) increase and ignition time decreases with hydrogen addition. It was also shown that the improving effect of hydrogen on the ignition temperature of the fuel and O(s) coverage is particularly evident at relatively low hydrogen fraction. The promotion of the combustion stability is due to the decrease of coefficient of variation with hydrogen addition. The methane combustion will move toward the more stabilized reaction and there is a great potential to reduce the pressure fluctuation.

•Increasing O2 content improves production of H2, CO and CH4 conversion efficiency.•650–750 K is an important transitional region of different reactions of CH4.•CO2 and H2O have no effect on H2, CO content as temperature below 650 K.•Effect of H2O on producing H2 is greater than CO2 especially at higher temperature.•H2O is more benefit to the improvement of the CH4 conversion efficiency than CO2.This paper focuses on investigating that the influence of O2, CO2 and H2O on characteristics of autothermal reforming of methane in micro premix chamber on Ni catalysts. In addition, the effect of catalytic wall temperature on autothermal reforming reaction of methane under a certain ratio of CH4/CO2/H2O/O2 is simulated. The results indicate that appropriately increasing O2 concentration can increase the conversion efficiency of CH4, so does adding CO2 or H2O. The positive effect of O2, CO2 and H2O is more pronounced at the higher temperature. The temperature range of 650–750 K is the important transitional region in the reactions of CH4/O2, CH4/H2O and CH4/CO2. It also gives a guide to the available range of parameters in the high efficiency reforming process of micro-reactor.

•Hydrogen effect is more significant at higher inlet velocity.•Effect of hydrogen is thermal as hydrogen fraction is less than 0.67%.•Thermal effect of hydrogen increases Rh(s) via adsorption–desorption balance.•Chemical effect of hydrogen increases Rh(s) via chemical effect.•Chemical effect addition reduces ignition temperature 15 K and distance 3%.In this paper hydrogen assisted catalytic combustion of methane on rhodium is numerically modeled in steady condition. The aim of the work goes to better understand how the addition of hydrogen affects the combustion of methane–air. For this purpose, a micro flatbed channel is investigated by a three-dimensional simulation including an elementary-step surface reaction mechanism. It is clearly shown through a numerical study that appropriate hydrogen addition increases the conversion of methane and expands the lower limit of burnable equivalence ratio. In addition, the main effect of hydrogen is thermal when the mass fraction of hydrogen addition is less than 0.67%, while not only thermal effect but also chemical effect appears when the mass fraction is more than 0.67%. The sharp decreases of hydrogen fraction appear twice till hydrogen fraction increases from 0.67%. In addition, the first abrupt decline increases Rh(s) coverage to create favorable conditions for adsorption and oxidation of methane and it can suddenly reduce the ignition temperature 15 K and advance ignition distance 3%. Thanks to the second sharp decline, the adsorption–desorption equilibrium of oxygen slowly shifts towards desorption with increasing temperature to increase Rh(s) coverage.

•We studied characteristics of methane autothermal reforming to generate hydrogen.•There is an inflection point temperature that the reaction turning to forward.•Changing the steam–methane molar ratio can regulate H2/CO mole ratio.The characteristics of methane autothermal reforming to generate hydrogen were studied with thermodynamic equilibrium constant method. Results show that the methane steam reforming reaction is prone to backward at low temperature, and there is an inflection point temperature that the reaction turns forward. When steam–methane molar ratio is 2, the inflection point temperature increases with raising air–methane molar ratio. When air–methane molar ratio is 1, the inflection point temperature maintains between 700 and 800 K. Hydrogen yield increases firstly and then decreases with elevated temperature. The increase of air–methane molar ratio leads to a lower hydrogen production when temperature exceeds 1000 K. Increasing steam–methane molar ratio promotes the hydrogen production. Methane autothermal reforming occurs much more easily when temperature keeps at 1000 K and the molar ratio of air–methane and steam–methane is 1 and 2 respectively. Changing the steam–methane molar ratio can regulate H2/CO molar ratio.

•Combustion characteristics of hydrogen addition on fuel was simulated.•Physical models with and without catalyst were compared.•Conversion rate of methane and hydrogen in the presence of catalyst improve significantly.•Addition of hydrogen supply enough heat for fuel to reach an ignition temperature.•Methane conversion increased as the wall temperature increases.Understanding of the chemical kinetics and heat transfer mechanism within micro-combustors is essential for the development of stable-combustion technology. Computational Fluid Dynamics (CFD) based numerical simulation has been proven to be an effective approach to analyze the performance of combustion under various conditions. The objective of this paper is to study hydrogen-assisted catalytic combustion of methane. It is proved that methane conversion rate decreases as the inlet velocity increases. The most suitable inlet velocity was 0.2 m/s, while the inlet temperature was 900 K. The ignition temperature will decrease considerably when hydrogen content of the fuel was increased with a fixed value of equivalent ratio, meanwhile, the moment of the ignition temperature advances and methane conversion rate also rises accordingly. This is useful for optimization micro combustion fuel.