Design And Process Of Catalyst Support With Porous Microchannel Composite Structure And Its Application In Microreactor For Hydrogen Production

With the aggravating unceasingly of the environmental pollution and the rapid depletion of fossil fuels,more and more attention has been paid to the development about new energy which is represented by hydrogen.Due to the small size and good safety,the methanol reforming reaction in the micro-reactor was seen as one of the most effective means of providing online hydrogen sources for tiny electronic devices.As we known,the porous metal used as catalyst support are characterized by multiscale surface morphology and microstructures.Up to now,a series of microchannel reactors have been widely applied in hydrogen production.Unfortunately,the porous materials had large pressure drop due to three-dimensional network structure.This disadvantage can produce an improper residence time of the reactants and a decrease in the diffusion capacity of porous materials,which affected the hydrogen production of microreactors.Inspired by the law of gas diffusion,a porous catalsyt support with microchannel structure was proposed to optimize the fluid diffusion and improve the hydrogen production of microreactor.The main work of this article includes:1.Design of methanol steam reforming microreactor equipped porous catalyst support with microchannel structure.According to the mass transfer mechanism and different applications of reactors,cylindrical laminated and plate methanol steam reforming microreactor were designed.Porous metal with different types of microchannel arrays were used as catalyst supports for constructing a cylindrical laminated methanol steam reforming microreactor.The surface microchannels with different sizes and qualities are proposed to optimize the geometrical structure of porous metal as catalyst support for plate methanol steam reforming microreactor.The uniform diffusion and optimal flow characteristics of fluid in porous metal can be achieved based on the novel designs.2.Performance investigation and structure optimization of catalyst support.Based on the support structure,the different models were established and the methanol reforming reaction was numerically simulated.Based on the diffusion of reactants,performance and optimal structure of catalyst support were investigated.The sphere-cut tetrakaidecahedrons model of cylindrical laminated porous support was established and macroscopic numerical analysis were used to analyze the reactants distribution.The macroscopic model was established by using the ANSYS/FLUENT module(Porous Media)for plate porous soppurt porous.According to the simulation results,the specific surface microchannels were constructed on the plate porous catalys support.It is found that the uniformity of flow distribution can be further improved with the composite structure of porous support.3,Investigation of milling process of porous catalyst support for pore structure protection.Based on the processing scale,two comformal processing technologies are proposed.One is laser cutting process for efficiently and directly cutting porous catalyst support into regular shapes.After analyzing the proposed laser cutting process,the effect of laser parameters on processing quality were investigated.The results show that metal foam with a good surface quality can be obtained without damaging the pore structure by using the proposed laser cutting process.When the laser output power is 26W and the scanning speed ranges from 400mm/s to 500mm/s,the best processing quality is obtained.Anthor one is a new milling method that different filling materials are used for solidification of pore structure.The effects of different filling materials and processing parameters on conformity of the porous structures were obtained and the cutting forces and temperatures are analyzed.The results show that better conformal effect is obtained with the spindle speed of 300r/min,the feed rate of 160mm/min and the hydrogenated rosin and sodium stearate at a ratio of 4:1.4.Reaction performance of methanol steam reforming microreactor for hydrogen production.A two-layer impregnation method was used to load the catalysts on the catalyst support with porous and microchannel composite structure.The ultrasonic water bath vibration method was used to evaluate the adhesive strength of the catalyst.A hydrogen production test platform was built and the reaction characteristics were investigatied under different flow rates of the reactant,reaction temperatures.The effect of the porous mental with the microchannel arrays on the reaction performance of the cylindrical laminated microreactor were.With the inlet flow rate of 10 ml/h and reaction temperature of 300℃ the best reaction performance of 95%methanol conversion and 0.52 mol/h H2 flow rate was obtained using the optimal composite structure catalyst support.The effect of different surface microchannel parameters including widths and quantities on the reaction performance of plate microreactor for hydrogen production was then investigated detailly.The gradient width(wider width at inlet and narrower one at outlet)of surface microchannel demonstrated the best reaction performance of microreactor for hydrogen production.In this condition,the methanol conversion reached 95%and H2 flow rates reached 0.53mol/h with the gas hourly space velocity of 16.25(L/(g.h)and the reaction temperature of 300℃ as well as a stable catalyst loading performance was obtained.