Optimization by Box-Behnken design of in-situ carbon dioxide conversion using lanthanum oxide

Abstract

Lanthanum oxide based catalyst was revealed as one of potential catalyst to convert carbon dioxide to wealth product methane in simulated natural gas. To produce higher conversion of carbon dioxide, the Response Surface Methodology utilizing Box-Behnken design (BBD) was used to optimize the lanthanum oxide based catalysts by three critical parameters which were calcination temperature, based ratio and catalyst dosage. The maximum CO2 conversion was achieved at 1000oC calcination temperature using 7 g of catalyst for 60% based loading. The optimization result from BBD is in good agreement with experimental data. The optimize parameters gave 99% of CO2 conversion determined using Fourier Transformation Infrared (FTIR) and yielded about 50% of CH4 at reaction temperature of 400 °C. X-ray Diffraction (XRD) analysis showed an amorphous structure with RuO2 as active species and Field Emission Scanning Electron Microscope (FESEM) illustrated the catalyst surface was covered with small and dispersed particles with undefined shape. EDX analysis revealed that when the calcination temperature was increased, the mass ratio of Ru increased.