Process optimization of DBD plasma dry reforming of methane over Ni/La2O3-MgAl2O4 using multiple response surface methodology

In this study, 10% Ni/La2O3-MgAl2O4 nano-flake catalyst was synthesized, characterized and tested in a catalytic dielectric barrier discharge (DBD) plasma for dry reforming of methane (DRM). With design of experiment (DoE), the influence of process parameters namely (1) total feed flow rate (ml min(-1)), (2) feed ratio (CO2/CH4), (3) input power (W) and (4) catalyst loading (g) were examined using multiple response surface methodology (RSM) through a four-factor, five-level central composite design (CCD). Second-order regression models were applied for evaluating the interaction between the process parameters and responses. Input power (X-3) and total feed flow rate (X-1) were the two most influential process parameters followed by catalyst loading (X-4) and feed ratio (X-2). The experimental and predicted results from the optimum conditions fitted-well with less than +/- 5% margin of error. The possible dynamic interactions between the process variables were elucidated. The optimum values are feed flow rate = 18.8 ml min(-1), feed ratio = 1.05, input power = 125.6 W and catalyst loading = 0.6 g. At these conditions, the predicted CH4 and CO2 conversions are 79.86% and 84.03%, respectively. The H-2 and CO yields are predicted as 41.37% and 40.47%, respectively while H-2/CO ratio is above unity. The calculated EE from the RSM model is predicted as 0.135 mmol kJ(-1). Low carbon deposition observed on the spent catalyst is attributed to the highly basic and oxidative nature of the La2O3 co-supported catalyst. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.