Modelling the Sintering of Nickel Particles Supported on γ-Alumina under Hydrothermal Conditions

Isabelle Champon,Alain Bengaouer,Albin Chaise,Sébastien Thomas,Anne-Cécile Roger

doi:10.3390/catal10121477

Abstract

Sintering of nickel particles is a well-known path of deactivation for Ni/Al2O3 catalysts. Considering the CO2 methanation in the context of Power-to-Gas, a sintering study for up to 300 h was performed in a controlled atmosphere between 450 and 600 °C. Since water is a product of the methanation reaction and is known to favor the particle sintering, the H2O:H2 molar ratio was varied in the range 0–3.2. Characterization of the post mortem samples showed sintering of both nickel and support particles. The absence of carbon oxides in the gas feed allows us to rule out other causes of deactivation such as carbon deposits. A sintering law is derived from the loss of metallic surface area with time-on-stream according to local temperature and H2O:H2 molar ratio. An excellent fit of the experimental data was obtained allowing the prediction of the metallic surface area within 15%.

Highlights

Power-to-SNG (Substitute Natural Gas) aims at storing and transporting the surplus production of renewable energy [1,2,3,4,5,6] as SNG in the infrastructures already existing for the natural gas
A supported catalyst is generally used for the CO2 methanation reaction and consists of a metallic phase (Rh, Ru, Ni . . . ) dispersed on an oxide support with a large surface area (Al2 O3, CeO2, SiO2 . . . )
Assuming nickel particle sintering is the principal cause of catalyst deactivation [11,14,15] the aim of the present study is to develop a sintering law in order to model the loss of catalyst activity with time on stream

Summary

Introduction

Power-to-SNG (Substitute Natural Gas) aims at storing and transporting the surplus production of renewable energy [1,2,3,4,5,6] as SNG in the infrastructures already existing for the natural gas. Hydrogen is generated by water electrolysis using renewable electricity and combined with carbon dioxide through the CO2 methanation; called the Sabatier reaction. When the CO2 is biogenic, this process leads to renewable SNG with no net CO2 emission. The CO2 reduction into methane in the gas phase is a difficult step since carbon dioxide is a very stable molecule. A catalyst is needed in order to obtain acceptable kinetics and methane selectivity. A supported catalyst is generally used for the CO2 methanation reaction and consists of a metallic phase ) dispersed on an oxide support with a large surface area A supported catalyst is generally used for the CO2 methanation reaction and consists of a metallic phase (Rh, Ru, Ni . . . ) dispersed on an oxide support with a large surface area (Al2 O3 , CeO2 , SiO2 . . . )

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Results

Conclusion