Methane steam reforming rates over Pt, Rh and Ni(111) accounting for H tunneling and for metal lattice vibrations

TY - JOUR

T1 - Methane steam reforming rates over Pt, Rh and Ni(111) accounting for H tunneling and for metal lattice vibrations

AU - German, Ernst D.

AU - Sheintuch, Moshe

N1 - Publisher Copyright: © 2016 Elsevier B.V.

PY - 2017/2/1

Y1 - 2017/2/1

N2 - Microkinetic models of methane steam reforming (MSR) over bare platinum and rhodium (111) surfaces are analyzed in present work using calculated rate constants. The individual rate constants are classified into three different sets: (i) rate constants of adsorption and desorption steps of CH4, H2O, CO and of H2; (ii) rate constants of dissociation and formation of A–H bonds (A = C, O, and H), and (iii) rate constants of dissociation and formation of C–O bond. The rate constants of sets (i) and (iii) are calculated using transition state theory and published thermochemical data. The rate constants of H-dissociation reactions (set (ii)) are calculated in terms of a previously-developed approach that accounts for thermal metal lattice vibrations and for H tunneling through a potential barrier of height which depends on distance of AH from a surface. Pre-exponential factors of several group (ii) steps were calculated to be usually lower than the traditional kBT/h due to tunneling effect. Surface composition and overall MSR rates over platinum and rhodium surfaces are compared with those over nickel surface showing that operating conditions strongly affect on the activity order of the catalysts.

AB - Microkinetic models of methane steam reforming (MSR) over bare platinum and rhodium (111) surfaces are analyzed in present work using calculated rate constants. The individual rate constants are classified into three different sets: (i) rate constants of adsorption and desorption steps of CH4, H2O, CO and of H2; (ii) rate constants of dissociation and formation of A–H bonds (A = C, O, and H), and (iii) rate constants of dissociation and formation of C–O bond. The rate constants of sets (i) and (iii) are calculated using transition state theory and published thermochemical data. The rate constants of H-dissociation reactions (set (ii)) are calculated in terms of a previously-developed approach that accounts for thermal metal lattice vibrations and for H tunneling through a potential barrier of height which depends on distance of AH from a surface. Pre-exponential factors of several group (ii) steps were calculated to be usually lower than the traditional kBT/h due to tunneling effect. Surface composition and overall MSR rates over platinum and rhodium surfaces are compared with those over nickel surface showing that operating conditions strongly affect on the activity order of the catalysts.

KW - H-tunneling

KW - Microkinetic modeling

KW - Steam reforming

UR - http://www.scopus.com/inward/record.url?scp=85006375568&partnerID=8YFLogxK

U2 - 10.1016/j.susc.2016.03.024

DO - 10.1016/j.susc.2016.03.024

M3 - 文章

AN - SCOPUS:85006375568

SN - 0039-6028

VL - 656

SP - 126

EP - 139

JO - Surface Science

JF - Surface Science

ER -