Catalytic reaction processes using microchannel technology for hydrogen production by steam reforming

<strong>Catalytic reaction processes using microchannel technology for hydrogen production by steam reforming</strong> Junjie Chen Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, 2000 Century Avenue, Jiaozuo, Henan, 454000, P.R. China Contributor: Junjie Chen, ORCID: 0000-0001-5055-4309, E-mail address: [e-mail] Two competing proposals have been made concerning the mechanism of catalytic reactions at surfaces, and it has not been possible to choose between them. Originally, Irving Langmuir, an American physical chemist, proposed chemisorption of both reacting species at the surface, followed by interaction between adjacent species and evaporation of the products. An alternative proposal involves interaction between an impinging molecule and species already adsorbed on the surface. Subsequent developments have suggested various modes of attachment of the adsorbed and adsorbing species. A major advance in the science of surface catalysis was the development of a method for determining the surface area of catalysts (and other materials) by measuring the multimolecular adsorption of nitrogen at liquid nitrogen temperatures or the adsorption of other gases close to their boiling points. It then became possible to calculate a quantity that represents the volume of gas necessary to form a monolayer on the accessible surface; furthermore, the area of the surface can be determined from the known dimensions of the adsorbed molecules. It has also been found possible to titrate (measure quantitatively) the area of surfaces by chemisorption of gases. Since heterogeneously catalyzed reactions occur on the surface of the catalyst, the rates of such reactions are proportional to the accessible surface area of the catalyst. Active catalysts are thus usually highly porous solids with total surface areas as high as several hundred square metres per gram. When measurements of surface areas became possible, it was seen at once that many constituents present in minor quantities in the main catalyst material, known as promoters, could act by extending the effective surface area of the catalyst. It also was shown, however, that a promoter might produce an increase in the quality of the surface for the given reaction. Acting in a reverse direction are minor constituents of the reacting system or unwanted products of the reaction, which by preferential adsorption on the reaction sites. Poisoning of a catalyst may also result from the poison adversely modifying the electronic properties of the catalyst. Streamwise distance (meter), Heterogeneous reaction rate along the length of the reactor (mole per square meter per second) 0 12.5259 0.00025 12.5249 0.0005 12.4628 0.00075 12.2996 0.001 12.0712 0.00125 11.8221 0.0015 11.596 0.00175 11.4118 0.002 11.2616 0.00225 11.1177 0.0025 10.9536 0.00275 10.759 0.003 10.5398 0.00325 10.3175 0.0035 10.1169 0.00375 9.94876 0.004 9.80787 0.00425 9.67857 0.0045 9.54646 0.00475 9.40536 0.005 9.25748 0.00525 9.11421 0.0055 8.98858 0.00575 8.88572 0.006 8.80178 0.00625 8.72615 0.0065 8.64819 0.00675 8.5635 0.007 8.47426 0.00725 8.38872 0.0075 8.31553 0.00775 8.2578 0.008 8.21239 0.00825 8.17077 0.0085 8.1251 0.00875 8.07247 0.009 8.01529 0.00925 7.9603 0.0095 7.91452 0.00975 7.88049 0.01 7.85474 0.01025 7.83035 0.0105 7.80092 0.01075 7.76453 0.011 7.72333 0.01125 7.68313 0.0115 7.65017 0.01175 7.62633 0.012 7.60882 0.01225 7.59146 0.0125 7.5688 0.01275 7.53904 0.013 7.50421 0.01325 7.4698 0.0135 7.4414 0.01375 7.42087 0.014 7.40548 0.01425 7.38911 0.0145 7.36723 0.01475 7.33882 0.015 7.30582 0.01525 7.27313 0.0155 7.24519 0.01575 7.22352 0.016 7.20619 0.01625 7.18805 0.0165 7.16393 0.01675 7.13321 0.017 7.09884 0.01725 7.06502 0.0175 7.03546 0.01775 7.01145 0.018 6.99108 0.01825 6.96922 0.0185 6.94195 0.01875 6.90861 0.019 6.8712 0.01925 6.83338 0.0195 6.79882 0.01975 6.76887 0.02 6.74161 0.02025 6.71249 0.0205 6.67791 0.02075 6.63756 0.021 6.59338 0.02125 &amp;nb