| Green chemistry has been recognized as one of the research frontier and hotspot in chemistry and chemical engineering field, not only including green chemical reaction, but also including green chemical processes, e.g., chemical process intensification. Microreactor, an important facility of chemical process intensification, can markedly increase conversion and selectivity, enhance energy efficiency, reduce reactor volume, and improve integration and safty of chemical process by carrying out reaction in micron space. New and innovative approaches in microreaction technology are laying the groundwork for potable hydrogen supply for polymeric electrolyte membrane fuel cell (PEMFC) and organic synthesis process. A novel monolithic microfibrous structured porous media (MMSPM) with sinter-locked three-dimensional microfibrous networks consisting of microfibers and entraped particulates was developed by using a high-speed and low-cost papermaking technology combined with subsequent sintering process. Taking advantage of large surface-to-volume ratios, large void volume, entirely open structure, high heat and mass transfer rates, high permeability, good thermal stability, and unique form factors, the MMSPM is a new type of material toward chemical process intensification and microreaction technology.With large void volume fraction and unique solid matrix, the fluid flow resistance of MMSPM cannot be calculated by permeability equation of particulate bed. Porous media can intensify heat transfer dramatically, but the processes of the thermal conductive and convective transfer in MMSPM need further study. The numerical simulation of flow, heat transfer and reaction process by using computational fluid danamics (CFD) software can save manpower, material resources and time which are needed in experiments and guide experiments. Moreover, we anticipate that MMSPM can be applied into microreaction technology to remarkablely intensify the chemical process while significantly reducing the overall reactor bed weight and volume. In accordance, the law of fluid flow, permeability and heat transfer intensification of MMSPM was studied deeply. Furthermore, a preliminary simulation of flow, heat transfer and reaction process was conducted by using detailed gas and surface catalytic reaction dynamic mechanisms combined with CFD software. At last, microreactors based on our novel MMSPM have been designed, fabricated and examined for portable hydrogen production from MeOH and NH3 in PEMFC applications and liquid-liquid organic synthesis reaction. In addition, new micro heat exchanger with super volumetic power has also been designed and fabricated by inserting MMSPM with three dimensional micron pore diameter into millimeter scale flow channels.In the first part, detailed study on the flow and permeability of fluid in the MMSPM has been made. For each experiment, the type of gas flow in the MMSPM was laminar flow, which adapted to Darcy law. The three dimentional microfibrous matrix with a little volume fraction in the MMSPM had a great contribution to the permeability. The density of entrapped particulates had no influence on the permeability of MMSPM. Reduction of void volume fraction and increase of microfibrous volume fraction in solid matrix could improve the flow resistance of MMSPM thereby degrading the permeability. Based on the capillary model of porous media and aboundant experimental results, the permeability equation (M-PMP) for MMSPM was developed, which could calculated the flow resistance of MMSPM with a maximum error of 10% from the properties of micro structure, such as shape, equivalent diameter and volume fraction of microfibers and particulates, etc. The fluid flow in MMSPM was numerically investigated by using the CFD software FLUENT coupled with M-PMP equation. Calculation results showed that fluid velocity had uniform distribution in MMSPM, and the pressure was reduced linearly along the flow direction. The simulation results of flow resistance in MMSPM were in good agreement with the experimental results.In the second part, experiments of heat transfer showed that the heat could be transfered quickly from tube inner wall to the center of MMSPM because of the high thermal conductive efficiency, which made 6-fold decrease of the temperature difference between tube inner wall and center of porous media from the MMSPM bed compared with particulate bed. The volumetic average effective thermal conductivity of the MMSPM consisting of～3 vol% metal microfibers was 30-50 times higher than SiO2 particulate bed. The average convection heat transfer coefficient could be increased 10-30 times for air in the MMSPM bed compared with the empty tube. Based on such high heat exchange efficiency of MMSPM, a high-performance counter-flow micro heat exchanger has been established by using a novel Ni microfibrous structured wick. The influence of micro heat exchanger structure parameters on heat transfer coefficient and pressure drop was presented. The results showed that the heat transfer performance of the micro heat exchanger could be enhanced dramatically by using a monolithic microfibrous structure consisting of 8μm diameter nickel fibers. The use of this approach provided 2-fold or more increase of the volumetric heat transfer coefficient from 13.3 MW/(m3K) at porosity 100% to 40 MW/(m3K) at porosity 95.1% under the compatible operating conditions. Reduction of porosity of the microfibrous structure and the flow channel depth promoted the heat transfer performance but caused large pressure drop. Moreover, the use of thinner heat transfer plate made by copper with higher thermal conductivity coefficient also provided significant promotion of the heat transfer performance at high flow rate. At a water volume flow rate of 14.6 L/h, the volumetric heat transfer coefficient of 40 MW/(m3K), equivalent to a gross heat transfer coefficient of 20 kW/(m2K), could be obtained at a low pressure drop of 0.2 MPa in micro heat exchanger with optimal design parameters such as sintered Ni microfibrous porosity of 95.1%, flow channel depth of 0.3 mm, coppery heat exchange plate thickness of 0.1 mm.In the third part, a methamol steam reforming (MSR) microreactor with integrated micro catalytic combustor was build for portable fuel cell power supply, which could improve energy efficiency of the whole reaction system. The micro catalytic combustor was studied as a heat source for MSR, which is made from inserting sintered Ni microfibrous entrapped fine particulates Pt/Al2O3 catalyst in a millimeter scale reaction chamber. The catalytic combustion performance of H2/Air in the microchannel at different experimental conditions and Pt loading has been investigated and the structure and properties of catalysts were characterized. The results showed that the normally highly explosive reaction of H2/Air can be conducted in this micro catalytic combustor with inherently safe operation. At 83℃and GHSV of 2.0×105 h-1 with 28.5 mol% H2 inlet concentration, hydrogen conversion can still be >92.2% over monolithic microfibrous entrapped 5wt% Pt/AlO3. By combining microreactor model, flow model, heat and mass transfer model, bonduary condutions of CFD software FLUENT and detailed gas and surface catalytic reaction mechanism files of chemical reaction dynamics software CHEMKIN, a numerical simulation was conducted for the catalytic combustion of a mixture of H2 and air in the micro catalytic combustor. The results of non-reaction simulation showed that the pressure and temperature had the same distribution in different micro-channels, and the mass fraction of different components was uniform in flow micro-channels.In the fourth part, a miniature ammonia cracker was developed for portable fuel cell power supply. The cracker, with overall weight of～195 g and a volume of～30 cm3, composed of a SS-316L tube body, a fixed heating rod along with the axis of tubular body, and novel microfibrous CeO2-promoted Ni/Al2O3 catalyst monoliths incorporated within the annular housing between the heating rod and the inner wall of the tubular reactor. This cracker showed pleasing operability for high efficiency H2 production via ammonia cracking with low pressure drop. Roughly 158 W equivalents of H2 could be produced with ammonia conversion of >99.9% at 600℃and 1100 standard cubic centimeter per minute (sccm) ammonia feed gas rate within this cracker through entire 250 h test. Power density and energy density was estimated to be～3160 W/L and～2150 Wh/kg, respectively. In addition, a combinatorial approach (e.g., array reactor) where several or more such ammonia crackers are combined together and run in parallel can be used for easily achieving >500 W equivalents of hydrogen generation. We believe that the array reactor can provide higher power/energy density compared with the single cracker, because of the expectable reduction of heat loss and overall system weight/volume. Moreover, in accordance with the microreactor design concept as described in this work, ammonia cracker for power supplies ranging from subwatts to several tens watts are also easier to be built up by using matchable heating rods including both diameter and heating power.In the last part, a novel microreactor with integrated heat-exchanger has been developed for strongly exothermic liquid-liquid reactions, on the basis of a novel metallic microfibrous structure. The microreactor was made from simply inserting quadrate pieces of the microfibrous media in the reaction and heat-exchanger chambers, respectively. This microreactor was examined in the use with the nitration of benzene. This new approach facilitates mass and heat transfer by taking the beneficial properties in terms of large void volume, three-dimensional micron-grade pore structure, and large surface area to volume ratio. Note that three-dimensional network structure acts as micromixer thereby leading to micronic segmentation and fast mixing of fluids. The results showed that nitration of benzene could proceed completely in this novel microreactor with high selectivity at a short residence time. The temperature in reaction bed changed slightly because of the aboundent reaction heat can be removed promptly by intergrated high efficient conter-flow micro heat exchanger. The selectivity of 99.6% to nitrobenzene could be achievable with a benzene conversion of 99.2% at an optimized experimental condition. This novel microreactor provided great chemical process intensification effciency compared with traditional kettle reactor. And the monolithic microfibrous porous media allows us to develop green microreaction process for benzene nitration by using entrapping super solid acid into its three-dimensional network to replace sulfuric acid entirely.
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