Dynamic Methanation of CO₂ – Effect of Concentration Forcing

Abstract

Investigating the effect of concentration forcing of the CO2 methanation is not only relevant for power‐to‐gas plants but also for the study of dynamic phenomena of this reaction. In this study a Ni/Al2O3 catalyst is investigated under concentration forcing at industrially relevant conditions. The dynamic experiments allow an evaluation in terms of the reaction rate and enable the study of the reaction mechanism. The experiments show that no methane is formed in the CO2‐rich part of the cycle, whereas a fast hydrogenation of carbonaceous species to methane takes place upon switching to H2.

Measuring Adsorption Capacity of Supported Catalysts with a Novel Quasi‐Continuous Pulse Chemisorption Method

“…The mean value multiplied with the time span is proportional to the amount of adsorptive leaving the system in this region, which can be derived from the integrated signal in a certain time interval [Eq. (14), with Eq. (11) and Dt ¼ t 1 À t 0 ].…”

“…The experimental study is performed with an 11 wt.‐% Ni/Al 2 O 3 catalyst prepared via incipient wetness impregnation of γ‐Al 2 O 3 with nickel nitrate . Therefore, the 160–250 μm sieve fraction of the support, the nickel salt and additional water are heated to 80 °C, mixed after melting of the nickel salt and subsequently dried under moving air in a furnace at 80 °C.…”

Transient Flow Rate Ramps for Methanation of Carbon Dioxide in an Adiabatic Fixed‐Bed Recycle Reactor

“…With the aim to reduce the costs of the hydrogen storage by minimizing upstream storage capacities (up to 8% of the total investment costs can be saved), the unsteady‐state operation of the exothermic methanation reaction is demanded. However, the occurring phenomena and operation strategies under dynamic conditions are not exhaustively addressed in scientific literature thus far, but receive more attention in recent years . One promising approach is adiabatically operated fixed‐bed reactors, which show a good partial and excess load behavior, since the chemical equilibrium is reached within the residence time.…”

“…In fixed‐bed reactors, the packed‐bed stores the heat and provides thermal inertia slowing down the transport of heat in the axial direction, leading to the inherent possibility of the DIFI formation . Under periodic concentration forcing, a relaxed steady state is reached in a cooled microreactor . Under isothermal conditions, the heat of reaction is not considered.…”

Modeling the Dynamic Power‐to‐Gas Process: Coupling Electrolysis with CO2 Methanation

“…A Langmuir-Hinshelwood-Hougen-Watson reaction rate expression from Koschany et al [12] is used for the CO 2 methanation kinetics on a Ni/Al 2 O 3 catalyst. This reaction rate expression is developed from steady-state experiments and, therefore, may not be able to capture dynamic phenomena correctly [13]. However, transient kinetic approaches are not available at the moment.…”