The Characterization of Kinetics By Singular Points: Comparison of Supported Vs. Unsupported and Isothermal Vs. Nonisothermal Pt Catalysts in Ammonia Oxidation

TY - JOUR

T1 - The Characterization of Kinetics By Singular Points

T2 - Comparison of Supported Vs. Unsupported and Isothermal Vs. Nonisothermal Pt Catalysts in Ammonia Oxidation

AU - Schmidt, J.

AU - Sheintuch, M.

PY - 1986/8

Y1 - 1986/8

N2 - Similar multiplicity features were observed during ammonia oxidation on supported or unsupported Pt catalysts, whether in the isothermal or nonisothermal modes of operation. Two types of isothermal multiplicity patterns were observed upon varying ammonia concentration. The simplest model predicting the transition between the two must have a pitchfork singularity. The same singularity accounts also for the diagrams observed with varying oxygen concentration. The singularities of the isothermal kinetics are inferred also from nonisothermal experiments. These similarities suggest that identical kinetic models are responsible for multiplicity in supported and unsupported catalysts. The dependences on either reactant is used to characterize the kinetics by defining the highest order singularity in the temperature—concentrations space. This information is utilized to develop the simplest rate expression which accounts for the observations. The two simultaneous reactions, producing N2 and N2O, were found to ignite and extinguish simultaneously.

AB - Similar multiplicity features were observed during ammonia oxidation on supported or unsupported Pt catalysts, whether in the isothermal or nonisothermal modes of operation. Two types of isothermal multiplicity patterns were observed upon varying ammonia concentration. The simplest model predicting the transition between the two must have a pitchfork singularity. The same singularity accounts also for the diagrams observed with varying oxygen concentration. The singularities of the isothermal kinetics are inferred also from nonisothermal experiments. These similarities suggest that identical kinetic models are responsible for multiplicity in supported and unsupported catalysts. The dependences on either reactant is used to characterize the kinetics by defining the highest order singularity in the temperature—concentrations space. This information is utilized to develop the simplest rate expression which accounts for the observations. The two simultaneous reactions, producing N2 and N2O, were found to ignite and extinguish simultaneously.

KW - Steady state multiplicity

KW - ammonia oxidation

KW - catalysis

KW - singularity theory

UR - http://www.scopus.com/inward/record.url?scp=0000311525&partnerID=8YFLogxK

U2 - 10.1080/00986448608911413

DO - 10.1080/00986448608911413

M3 - 文章

AN - SCOPUS:0000311525

SN - 0098-6445

VL - 46

SP - 289

EP - 309

JO - Chemical Engineering Communications

JF - Chemical Engineering Communications

IS - 4-6

ER -