Inserted-Plate Coated of Methanol Steam Reformer

Inserted-Plate coat of Methanol Steam ReformerHigh Efficiency Inserted-Plate Coated of Methanol Steam Reformer PEM Fuel Cell ApplicationsMethanol bottomland be easily stored and transported and converted to H2 using a reforming nuclear nuclear reactor that makes it an brilliant heat content and force source for fuel booth applicationsEasily storage, transporting and converting to H2 by a reforming reactor using makes it an excellent energy source for PEMFC applications 1-3During the last decades, at that place has been a growe inte remnant on developing technologies taking vantage of clean energy sources. The reduction of atmospheric pollution and, namely, the dismission of babys room gunmanes earn become imperative and, among the new technologies for mitigating these emissions, fuel cells go the might to efficiently convert chemical into electrical energy. In particular, PEMFCs be zero-pollutants emission systems because they transform the chemical energy of the electr ochemical reply within hydrogen and oxygen into clean electrical agentTodays, for environmental issues, growing interest on developing technologies including clean energy sources has been focuse. Pollution issue and, especiall(a)y, the emission of greenhouse brages have become crucial and, the new technology for elimination of these emission, discharge be achieved by PEMFC. 4, 5Meanwhile, compargond to separate feedstocks, methyl alcohol ontogenesis marchs various advantages as a hydrogen carrier for fuel cell applications and, namely, it can be produced from renewable sources9, and the reforming response occurs at relatively low temperatures, ca. 240260 1CAmong these, methanol exploitation leads various advantages as a hydrogen carrier and, especially, reforming reaction applying at relatively low temperature (240-260 C)6 , compared to the methane reforming, usually performed at 8001000 1C, compared to the methane reforming, normally hold in out at 800-1000 C7 . Metha nol go reforming (MSR) reaction has been seen as a very attractive and promising procedure for hydrogen production and, fit to the scientific literature on the argument, it can be descri make do by the adjacent chemical reactionsAttractive and promising of the methanol steam reforming process cause especial insight to this reaction which agree to the scientific references, occurs by the hobby chemical reactions Where reactions 1, 2 and 3 represend MSR reaction, wet gas shift reaction and methanol decomposition reaction, respectively.Reaction (1), represents MSR reaction, reaction (2) represents water gas shift reaction and reaction (3) represents the methanol decomposition reaction The reactor design has direct impact on the reaction conversion, but owing to spunkyer technical complexity and manufacturing costs of other designs, the reformers and MRs are normally tubular. However, recent efforts in the champaign of small-processing made possible and easier to manufacture o ther reactor designs and namely well- grammatical constructiond at micro-reactors. A micro-reactor is defined as a device that contains micro structured features, with a sub-millimeter dimension, in which chemical reactions are performed in a continuous manner They present advantages compared to conventional ones much(prenominal)(prenominal) as higher surface-to- bulk ratio, smaller mean distance of the specific uid volume to the reactor walls, better heat and matter transfer properties and ow patterns that fit with the reaction needs. Furtherto a greater extent, at reformers are suitable for piling integration with fuel cells. Packed-bed micro-reactors request well-define gas pedal particles, with regular shape and much smaller than the internal dimensions of the micro-impart, which is a problem for most of commercial catalysts.The reactor design, directly impress reaction conversion but owning to higher complexity and fabrication costs should be considered. Common normally MR s are in tubular shape. However, recent researches show easier to manufacture and possibility of other designs and namely well-structured flat micro-reactors. A reactor containing micro structure features and sub-millimeter dimension through performing in a continues manner representing advantages such as higher surface to volume ratio, smaller mean distance of the specific fluid volume to the reactor walls, improve heat and people transfer make book situation of stack integration with fuel cells. 8.Many studies have been developed to explore the advantages of micro/mini-reactors to produce hydrogen through MSR The design of a reactor targets the maximization of the conversion and selectivity at the lowest costs and its performance is inuenced by the ow pattern, velocity profile, compel drop and heat transfer, so all these aspects mustiness be consideredTo fabricate an beliefive micro-reactor having maximum conversion and selectivity at a low cost is impressed by the flow pat tern, velocity profile, pressing drop and heat transfer, therefore all these approaches should be considered9. For conducting MSR reaction, most of the used reactor designs are rectilinear television conduct, pin-hole, coil- base and radial (Fig. 2).Coil-based reactor designs allow high conversions, but impose a significant pressure drop penalty, which may be a limitation for compact applications Categorization of the design incorporate rectilinear tunes, pin-hole, coil-based and radial (Fig. 2). Among these, Coil based leads high conversion and pressure drop preventing compact applications9. In the other hand, the rectilinear channel designs represent a small-pressure drop, but the conversion is low due to uneven mint distribution and is affected by the Reynolds number while, the first exhibit a small pressure drop, uneven mass distribution cause trim down conversion which impressed by Reynolds number9. Yet, by adjusting the channels width 69 or by imposing a pressure drop at the channels entrance even distributions on rectilinear channel designs can be obtained, improving the methanol conversion10.Conventional jammed-bed reactor has disadvantages, such as zealous spots, delays in start-up, and mass and heat transfer limitations. For micro-scale reactor, the pressure drop is some higher due to quadruplet constraints of channels existence blocked with catalysts. A micro-pump used in portable applications may not be adapted of oercoming a high pressure drop. On the other hand, microchannel reactor offers advantages, such as fast heating and cooling, large surface-area-to volume ratios, and less energy input The packed-bed reactors as a classic system, have disadvantages, such as hot spot, slow start-up, and heat and mass transfer limitations. Micro-structure scale of this gathering utilizing a micro pump is necessary, due to high pressure and channel blockage 10. Some research has shown that wall-coated reactor performs better than packed bed rea ctor for SRM reaction various researches has proofed better performance of the wall-coated than packed bed reactor for SRM reaction11, 12.Experimental gas preparationFirstly, 200 ml deionized water was heated to 80C and then metal nitrates of Cu, Zn and Fe (to prepare CuZnFe) were dissolved into the water until get the 0.2M solution. This solution was added to the heated water (80C) over stirrer under 350 rpm. To control and adjust pH around 7, the precipitation agent of 0.5M Na2CO3 was used. The obtained precipitates were aged at 60 C for 2 h under vigorous inhalation. Afterward, the solids were filtered and washed with warm deionized water for several periods and dried at 110 C for 12 h. then, the dried powder was calcined in a furnace at 350 C for 4h.Catalyst slurry preparationPVA (87-90% hydrolyzed, average mol wt 30,000-70,000,SIGMA-ALDRICH) was added to deionized water first, and stirred at 70 C until totally dissolved, then cooled at room temperature. As-synthesized, supe rior CuZnFe catalyst (10 wt.% catalyst) was added into the PVA solution (0.5 wt.%, 1 wt.%, 2 wt.% PVA) as-prepared. The catalyst slurry was unplowed in the ultrasonic vat for 1 h.Catalyst conclusion by electrophoretic deposition on faultless steel platesTo prepare a regular, controlled catalytic layer, a well-stable suspensions of the catalyst powder are necessary which compute on the particle size, solvent characteristics and additional agents. To do this, the powder were urbane to get a uniformity of particle size distribution at a scorn place 40 micron, at least. Isopropanol was selected as solvent due to lower conductivity limiting solvent transportation than of the sedimentary ones. Moreover, presence of aqueous base cause water electrolysis following poor counterbalanceage of catalyst. electrophoretic deposition was performed at continual voltage (140 V) using a power supply unit (SPS-900NP-Navasanpardaz). The stainless steel (AISI-304) palates (7.04 cm2) were used as electrodes in the EPD bath. To cover both sides of the plate, a system including trey electrodes was selected which, were mounted at a distance of 15 mm in a cell with a total volume of 120 ml. slurry of 72 g/L of catalyst in isopropanol and 1 g/L of PEI as binder was prepared through 15 min strongly stirring and then, 15 min signification in an ultrasonic bath (1200M-Soltec). The epoch of 4 min as diligence time was fixed for all samples. After coating, the plates were dried in room temperature and then calcination at 350 C for 2 h.Method and materialsAccording to the procedure in fig. 1, a series of CuZnFe slurries and samples were prepared. The synthesized powder was milled at 250 rpm for 10 min (due to sign fine powder structure short milling time was chosen) by a milling apparatus. It make a stable behavior of the slurry and self-coloured final layer deposited.Results and DiscussionAfter the coating procedure, the changing structure of the CuZnFe catalyst, the operating parameters and micro-channel characterization affect the efficiency of hydrogen in the output. In this study, explored a number of vital parameters characterization, including channeling arrangement and shape, coating methods and the efficiency of hydrogen production.Micro-Channeling TheoryDesign and micro-channel arrangement optimization cause select an appropriate structure limited by performance efficiency, constant cost wish startup, Fabrication, and variable costs (Catalyst stability, coated layer quality, appropriate life time). careless(predicate) of the constant costs, overall state and changing catalytic plates while the plates have been channelized, replacement and re-channelizing, coating procedure should be more difficult. Although, chein et. Al. 13 adopt three types reformer including the microchannel, the plain channel and the inserted catalyst layer while utilizing channeling over cover plate is divergent. All proposed structure of a square microchannel have been s hown below.In this research, flexibility and replacing of an aged micro-reformer has been emphasized, an appropriate pattern with the minimum of fabrication cost through a recoverable coating procedure, minimum catalyst consuming and high efficiency has been adopted. A set stainless steel as active layer was coated by the high efficiency CuZnFe catalyst which coated in an electrophoretic bath under a high controlling ability condition. The EPD producer will be discussed elsewhere, in detail. According to the optimum condition of a constant parameters, type of micro-channels, space and stability have been investigated.Reactor designThe reactors were knowing as flat-plate composed of stainless steel 304 plates. The microstructures were introduced by CNC technology. The both cover plate were machined to cover the active catalytic layer and increasing area to volume concept. The active layers were coated by home-made synthesized high efficiency steam reforming catalyst. Subsequently , the housing sealed by graphite gasket and bolts. The size and number of channels are summarized in table 1.Table 1.Summary of the dimensions of the reactor the channel dimensions are only provided for the reformate side of the platesParallel channelZig-zag channelLength(mm)Wide(mm)Depth(mm)Length(mm)Wide(mm)Depth(mm)The running play plates and reformer design details are shown in fig. 1. On the covering side of the cover plate, as shown in fig. 1(a), microchannel were patterned zig-zag path to tighten pressure drop along the path, holding high activity of the catalyst through the get hold of time increasing.(ref) the feed methanol-water mixture is sent to the vaporizer voice including an inert alumina granule packed developing the heat transfer, and then, collected in an triangle manifold in the reformer inlet to obtain a more uniformly distributed flow. The design of the reformer channel (as shown in fig) leads splitting-jointing in an alternatively manner. In order to ident ify the reactant flow pattern effect on the reforming performance, the reformer channels shown in fig.1 were investigated.Catalyst coatingThe results of coating procedure, have been shown in fig 2. For all the plates, the same catalyst lade of 25mg was coated.Experimental setupA schematic diagram of the tasteal setup is shown in fig. 3. The main components of the system are reactants, micro-reformer and products. To provide the heat of the reaction an electrical furnace was used controlled by a TIC. The feedstock system including methanol-water in liquefiable phase was sent by a syringe pump ( put nnn) in a designed feed composition and determined S/C= 1.3 in all the tests. The reformed gas stream was then sent to a cold trap to eliminate the unreacted liquid phase. In continues, the rest of the gases was conducted to a gas chromatography equipped via two columns of carboxen and hysep Q (model shimadzu GC-8A). Based on the achieved fractions and compositions, the methanol conver sion, CO selectivity, hydrogen yield and stability of the active layer cab be achieved. A K-type thermocouple connected at the end of the holes which designed to measure temperature of determined spots along the axis, default of the measurement is based on the central point of the reformer for all the tests.Results and Discussion50 mm collimate microchannelFig. 4 and fig. 5 display the performance of the microchannels according to the length. The investigation was performed under antithetical temperature and micro channel types. It can be observed that the methanol conversion rates with various lengths is no different although the magnitude of this depends on the micro channel arrangement and for the direct replicate channels is more obvious. In the experiments, the effect of reaction temperature could overcome length and enough conversion of methanol was achieved, finally. For the zig zag type, by disagreement in length in a range of 20 to 50 mm, no difference was observed. The arrangement cause more efficiency in reduction of surface to volume ratio. Actually the need of a commensurate contact time of the reactants on the catalytic active sites is necessary for a satisfying conversion. In the zag-zag type the contact time will change magnitude and the at least of the sufficient length of full conversion is roughly 25mm. other lengths below those was not possible due to the limitation of the mass flow controller. On the other hand, being endothermic of MSR, the least necessary heat of reaction can be supplied by increasing of the contact time on the cover plate which is contacted to the heating source, consequently following the micro channel length. About the CO content, however, due to being full conversion in considered lengths, there is no significant different among the cases. high conversion can cause producing some more CO in the outlet. On the other hand, sufficient existing catalyst affect the CO production due to being active rWGS in low er commitment of the catalyst. (ref).Zig-Zag microchannelFelani et al. proposed that a novel channel arrangement with a certain surface could guarantee better flow distribution, higher contact time being accessible of reaction and heating, and lower pressure drop than those of conventional ones. The proposed model can development the methanol conversion. Fig. 6 shows the illustration of the micro-reactor with such zig-zag microchannel. The performances of parallel microchannels and that of zig-zag microchannels are compared by the present experiment. The micro-reactor in this study is different from that of chein et al. 13. In cheins paper, the reactor only has simple inserted plate without channelizing. It is noticed that in this experiment novel catalyst of CuZnFe has been used and the goal of this experiment is not the comparison of the cases. Advantages of easily replacing, lower costs of recoating and flexibility managing of the fuel processor. Fig. 7 shows the variation of the methanol conversion with the temperatures. It can be found that with the increase of the temperature, the methanol conversion decrease. The conversion in zig-zag microchannels were higher than those in parallel microchannels. When the temperature is high, methanol conversion in zig-zag microchannels could be 20% higher than that in parallel microchannels. As mentioned before, zig-zag microchannels induce potential of providing more contact time to react under the help of catalysts, thereby enhancing the methanol conversion.ConclusionsIn this paper, the experiment of methanol steam reforming were performed in a micro-reformer coated with novel CuZnFe catalyst. The following conclusion can be achieved.1. The impacts of reaction temperature, gas hourly space velocity, H2O-to-CH3OH molar ratio and catalyst stability were also investigated in this stainless micro-reformer. Condition selection of optimum operation can be achieved by these useful guidance.2. Micro-reactor with two t ypes microchannel arrangement, including zig-zag path and parallel microchannels, different lengths of 15, 30 and 60 mm were evaluated. It is found that methanol conversion in microchannels with zig-zag path are much higher than that of parallel path. In addition, since zig-zag path cause more contact time of the reactants on active sites of catalyst, there is no different of methanol conversion with length variation, while in the parallel path, it was obvious that higher length leads to more methanol conversion.References1 D.R. Palo, R.A. Dagle, J.D. Holladay, chemical Reviews 107 (2007) 3992-4021.2 L. F Brown, supranational Journal of total heat Energy 26 (2001) 381-397.3 C. Liao, P.A. Erickson, International Journal of Hydrogen Energy 33 (2008) 1652-1660.4 J.-H. Wee, Renewable and sustainable energy reviews 11 (2007) 1720-1738.5 S. Bose, T. Kuila, T.X.H. Nguyen, N.H. Kim, K.-t. Lau, J.H. Lee, give in Polymer erudition 36 (2011) 813-843.6 R.Y. Chein, Y.C. Chen, Y.S. Lin, J. C hung, International Journal of Energy search 36 (2012) 466-476.7 A. Basile, A. Iulianelli, T. Longo, S. Liguori, M. De Falco, Membrane Reactors for Hydrogen Production Processes, Springer, 2011, pp. 21-55.8 V. Hessel, S. Hardt, H. Lwe, Chemical micro process engineering fundamentals, modelling and reactions, John Wiley Sons, 2006.9 H. An, A. Li, A.P. Sasmito, J.C. Kurnia, S.V. Jangam, A.S. Mujumdar, Chemical Engineering Science 75 (2012) 85-95.10 X. Ouyang, L. Bednarova, R. Besser, P. Ho, AIChE journal 51 (2005) 1758-1772.11 A. Karim, J. Bravo, D. Gorm, T. Conant, A. Datye, Catalysis today 110 (2005) 86-91.12 J. Bravo, A. Karim, T. Conant, G.P. Lopez, A. Datye, Chemical Engineering Journal 101 (2004) 113-121.13 R.-Y. Chein, Y.-C. Chen, Y.-S. Lin, J. Chung, International Journal of Thermal Sciences 50 (2011) 1253-1262.