Supplementary Information The Interplay of Kinetics and Thermodynamics in the Catalytic Steam Methane Reforming. over Ni/MgO-SiO 2

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1 Sulementary Information The Interlay of inetics and Thermodynamics in the Catalytic Steam Methane Reforming over Ni/Mg-Si Naoi ageyama a, Brigitte R. Devocht b, Atsushi Taagai a, enneth Toch b, Joris W. Thybaut b *, Guy B. Marin b, S. Ted yama a,c * a Deartment of Chemical System Engineering, The University of Toyo, 7-3- ongo, Bunyo-u, Toyo, , Jaan b Laboratory for Chemical Technology, Ghent University, Tech Lane Ghent Science Par Camus A, Technologiear 9, B-905 Ghent, Belgium c Environmental Catalysis and Nanomaterials Laboratory, Deartment of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacsburg, VA 06-0, United States *Corresonding authors: ST oyama@vt.edu, JWT joris.thybaut@ugent.be

2 I. The reversibility of the water-gas shift reaction was accounted for by using the equilibrium relation. S = = Eq. S The rate exression of the methane steam reaction is not altered. ( ) ( ) ' C C C C tot zc r = = Eq. S The rate exression for the water-gas shift reaction is altered by addition of the bac-reaction term. C S C C C S C C tot C r ' = = Eq. S3 In order to solve the lug flow reactor model,, the rate exressions are substituted in the net rate of formation R i for each comonent (Eq. -6). The results are resented in the following ages, as comarisons of the simle model resented in the main text and the simle model with the reverse water-gas shift incororated. As will be seen, there is little difference between the models.

3 Simle model 65 C conversion / % inlet artial ressure / Pa Simle model with reverse water-gas shift. 65 C conversion / % inlet artial ressure / Pa Fig. S. C conversion as a function of the inlet ressure at a total ressure of 0.0 MPa and 93. Points: exerimentally observed, lines: calculated by solving the set of Eqs. 8 with the net rates of formation given by Eqs. to 6. The rate and equilibrium coefficients are estimated by a weighted regression and are shown in Table., full line, blac - 0 Pa C inlet artial ressure ( 0 C) or a sace time of 3.36 g s mol -,, dashed line, red - 80 Pa 0 C or.68 g s mol -,, dotted line, blue - 0 Pa 0 C or. g s mol -. Simle model.

4 35 85 Selectivity to C / % Selectivity to C / % inlet artial ressure / Pa Simle model with reverse water-gas shift Selectivity to C / % Selectivity to C / % inlet artial ressure / Pa 65 Fig. S. Selectivity to C and C as a function of the inlet artial ressure of at a total ressure of 0. MPa, a temerature of 93, a sace time of. g s mol - and conversions between 0 % and %. Points: exerimentally observed, lines: calculated by solving the set of Eqs. 8 with the net rates of formation given by Eqs. to 6. The rate and equilibrium coefficients are estimated by a weighted regression and are shown in Table., full line, blac - selectivity to C,, dashed line, red - selectivity to C. Simle model

5 00 80 Selectivity / % C conversion / % 00 Simle model with reverse water-gas shift 80 Selectivity / % C conversion / % Fig. S3. Selectivity to C and C as a function of the conversion at a total ressure of 0.0 MPa, a temerature of 93, a catalyst mass of 0. g, a inlet artial ressure of 60 Pa and a C inlet artial ressure between 0 and 00 Pa. Points: exerimentally observed, lines: calculated by solving the set of Eqs. 8 with the net rates of formation given by Eqs. to 6. The rate and equilibrium coefficients are estimated by a weighted regression and are shown in Table., full line, blac - selectivity to C,, dashed line, red - selectivity to C.

6 II) Calculation of lac of heat transfer limitations Mears Criterion h <0.5 : eat of the reaction [J/mol] r: reaction rate [mol/s m 3 ] d: distance between tubes [m] h: heat transfer coefficient [J/m s] T: temerature [] E: activation energy [J/mol] R: gas constant [J/mol ] = -.0x0 5 J/mol (reaction heat of SMR) r = 5.77x0-3 mol/s m 3 (catalyst bed) or mol/s m 3 (catalyst article) d = (ID quartz - D alumina )/ =.5 x0-3 m h = 770 J/m s (calculation is described later) T = 93 E =.5x0 5 J/mol As the mean value of following reorted values Xu-Froment(989) 0 J/mol Yang(05): 3 J/mol (ref. 8 of MS) Numaguchi(988) Saito(05) 3 ughes(00) R = 8.3 J/mol h 07 J/mol 99. J/mol 09 J/mol = =8. 0 The criterion is calculated to be 8.x0-5, which is much lower than 0.5 thus the heat transfer can be ignored.

7 Details of calculations: Fig. Reactor used in the steam methane reforming studies C consumtion rate.69x0-5 mol / s Catalyst weight g Catalyst bed volume.95x0-6 m 3 Catalyst density 500 g/m 3 Total Pressure 0.0 MPa Profile of flow(outlet flow) Pressure: 0. MPa, Temerature: 93, Total mole flow: 309 µmol/s (5 Ncm 3 /min) F C :.8 µmol/s F : 68.7 µmol/s F C : 3.5 µmol/s F C : 3.3 µmol/s F : 0 µmol/s F N : 09 µmol/s Calculation of h h= / = 8. / µ f : viscosity of flow [g/m s] ρ f : density of flow [g/m 3 ]

8 u: linear velocity [m/s] d: secific length C f : secific heat of flow [J/g ] G f : mass velocity [g/m s] µ f = 3.x0-5 g / m s ρ f = 0.09[g/mol] / (8.3[J / mol] x 93[] / x0 5 [Pa]) =.00 g / m 3 u = 5[Ncm 3 /min]/60[s/min]/(( )π[cm ])/00[cm/m]/(0./0.)[Ncm 3 /cm 3 ] = 0.09 m / s d = m C f = 97 J / g G f = u x ρ f = 0.09[m/s] x.00 [g/m 3 ] = 0.09 g / m s h = 8. x 3.x0-5 / (.00 x 0.09 x 0.005) x 97 x 0.09 x (0. / (3.x0-5 x 97)) /3 = 770 J / m s Gas roerties are shown in Table A. The values of at 650 o C was calculated as (total, 650 o C) = (total, 00 o C) x [(air, 00 o C)/(air, 650 o C)] and C at 650 o C was calculated in the same manner. The values of (air, 650 o C) and C (air, 650 o C) was obtained from Fig. Sa and Sb resectively. Table S. of gas roerties (00 o C) C(00 C) M [J / m s ] 5 [J / g ] 6 [g / mol] C'(00 o C) [J / mol ] µ (600 o C) [g / m s] 7 C x x0-5 C x0-5 C x x0-5 N x0-5 Total x0-5 Total(650 o C)

9 /J m - s - - a b C /J g Temerature / 0 Temerature / Fig. S. a) The temerature deendency of thermal conductivity of air 5 b) The temerature deendency of secific heat of air 6

10 Xu, J.; Froment, G.F. Methane steam reforming, methanation and water-gas shift: I. intrinsic inetics. AIChE J. 989, 35, 88. Numaguchi, T.; iuchi,. Intrinsic inetics and design simulation in a comlex reaction networ: steam-methane reforming. Chem. Eng. Sci. 988, 3, Saito, M.; ojima, J.; Iwai,.; Yoshida,. The limiting rocess in steam methane reforming with gas diffusion into a orous catalytic wall in a flow reactor. Int. J. ydrogen Energy 05, 0, 88. ou,.; ughes, R. The inetics of methane steam reforming over a Ni/α-Al3 catalyst. Chem. Eng. J. 00, 8, 3. 5 htt://wiitech.info/7 6 htt:// 7 htt://