Steam Reforming of Ethanol Using a Commercial Nickel-Based Catalyst

Abstract

Kinetic study of ethanol steam reforming over a commercial nickel−magnesia−alumina (Ni/MgO/Al2O3) catalyst was conducted in a fixed-bed reactor 15 mm in diameter. The effects of temperature (673−873 K), molar ratio of steam to ethanol in the feed (in the range of 3:1 to 18:1), feed flow rate (W/F EtOH = 46.2−555.25 g-cat min/mol), catalyst particle size (2.25−0.75 mm), and time-on-stream study was studied. Maximum conversion (>95%) was obtained at 873 K, with a molar ratio of steam to ethanol of 12:1 and a W/F EtOH value of >185 g-cat min/mol at atmospheric pressure. A maximum yield of 3.0 moles of hydrogen per mole of ethanol fed was obtained at a temperature of 873 K, a steam-to-ethanol molar feed ratio of 12:1, and a W/F EtOH value of >110 g-cat min/mol. The acquired data was fitted to a power-law kinetic model and the kinetic parameters were evaluated. The activation energy was determined to be 23 kJ/mol. The average absolute deviation (AAD) for the predicted rates of reaction was determined to be 10.2%. The work also tested the feasibility of using the Eley−Rideal mechanism proposed in the literature and concludes that a more-elaborate scheme of reactions is necessary to describe the complex reactions that occur during the steam reforming process. A considerable amount of coke formation was observed during the process; yet, the catalyst showed a negligible loss of activity, exhibiting the feasibility of using this catalyst for ethanol steam reforming. In an attempt to reduce this coke formation, it is suggested that the process may be performed in the presence of hydrogen gas.

Kinetic Modelling at the Basis of Process Simulation for Heterogeneous Catalytic Process Design

“…This kind of analysis is used in [37][38][39], where catalysts of Ru/Al2O3, Ni/MgO/Al2O and Ni/Al2O3 yielded the following kinetic parameters (Table 9). Notice very small values of the activation energy, which may indicate the presence of diffusional limitations or of highly correlated parameters.…”

Catalytic Hydrogen Production from Bioethanol

“…However, the knowledge accumulated during the systematic explorations of the kinetic mechanisms occurring during MSR provides a valuable starting point for ESR researchers to expand upon. In recent years, based on the observations obtained from both gas phase and sample surface, several kinetic models have been proposed to simulate the mechanistic behaviors of various catalyst systems [128][129][130][131][132], which will facilitate better understanding of the reaction mechanisms. If the estimated values are in good consistency with the reported experimental results, the assumed reaction pathways and ratedetermining step (RDS) will uncover the actual reaction mechanisms to a certain level.…”

Microkinetic modeling and analysis of ethanol partial oxidation and reforming reaction pathways on platinum at short contact times

“…Thermodynamic analysis for ethanol reforming has been carried out to understand the effect of operating conditions on product selectivities and yields [41][42][43]. A number of studies have focused on developing Langmuir-Hinshelwood-Hougen-Watson (LHHW) or Eley-Rideal rate expressions followed by data fitting of the kinetic parameters [44][45][46][47].…”