Fluidized-Bed Methanation: Interaction between Kinetics and Mass Transfer

Abstract

In the present work, the influence of reaction and mass transfer on the fluidized-bed methanation have been investigated by both experiments and modeling. By applying spatially resolved gas concentration and temperature measurements in a bench-scale fluidizedbed reactor, it was shown that most of the reaction proceeds in the first 20 mm while the temperature increases by 74 K in the first 2 mm of the bed. A CO conversion of practically 100% is achieved. The experimental data indicate that the measured gas composition represents mainly the dense phase and that mass transfer between bubble and dense phase is the dominant effect in the upper part of the bed. A fluidized-bed model is proposed based on the two-phase model approach, hydrodynamic correlations from the literature and kinetic parameters previously determined. Although it was not possible to reproduce all measured phenomena within the methanation reactor, this first attempt to model the fluidized bed provides a better understanding of the behavior of the reactor and the reactions.

CO methanation over TiO2-supported nickel catalysts: A carbon formation study

“…Methanation is a key step in the production of SNG and great efforts are made in the development of efficient catalysts [9][10][11][12][13][14] and reactor systems [15][16][17][18][19][20]. Among all the materials which catalyze the methanation reaction, nickel-based catalysts are preferred due to their high activity, selectivity towards methane and relatively low cost [21,22].…”

Impact of reducing the channel diameter on heterogeneous gas reactions in an isothermal monolith

“…The operating conditions at channel inlet were not the same for each tested device in the study of Using Equations (13) to (20) The Peclet numbers presented in Table 5 for the three devices show that the conventional monolith (CM) and the micro-reactor (MR) can be modeled as plug flow reactors without axial dispersion.…”

Improved Kinetic Data Acquisition Using An Optically Accessible Catalytic Plate Reactor with Spatially-Resolved Measurement Techniques. Case of Study: CO2 Methanation

“…Working under industrially-relevant conditions usually requires a continuous process using an integral reactor, which has significant heterogeneities such non-uniform catalyst mass distribution, concentration and temperature gradients along the axial and radial directions. Kinetic measurements and modeling are difficult due to the lack of knowledge of these gradients [1]. For reactors without gas recirculation, each experiment results in a single data point per gas species.…”

“…For example, direct sampling of the gas phase and temperature along the reactor axis can be achieved using a movable capillary and thermocouple or pyrometers, respectively, or via multiple fixed probing. These techniques have been applied in different reactor configurations such as monolith [3][4][5], coated metal foam [6][7][8], fixed bed [9] and fluidized bed [1]. The main disadvantage of the aforementioned setups is the unknown catalyst mass distribution along the reactor axis between the sampling points, thus they are not suitable for kinetic data collection.…”