Development of highly active Cu-based CO2 hydrogenation catalysts by solution combustion synthesis (SCS): Effects of synthesis variables

Abstract

This work investigates the effects of solution combustion synthesis (SCS) variables on the performance of copper-based catalysts for CO2 hydrogenation to methanol. The catalyst with a composition of 30wt%CuO50%ZnO/Al2O3 was prepared at various glycine to nitrates (G/O) ratios in the range between 0.1 and 1.23. A correlation of the effects of calcination and activation temperatures with catalytic activity was also studied. The catalyst synthesized at a G/O ratio of 0.206, calcined in air at 400 °C and activated in a stream of pure hydrogen at a temperature of 350 °C resulted in a significant improvement in the performance of the catalyst for CO2 hydrogenation. The exceptionally high catalytic performance of the catalyst was attributed to the synergic effects between small well-dispersed CuO nanoparticles and high number of induced copper phases. The highest activity of the catalyst was recorded at an operating temperature of 300 °C, a pressure of 85 bar and GHSV of 7000 h−1. The CO2 conversion, CO selectivity and methanol selectivity under these conditions were 30%, 38.60%, and 61.4%, respectively; whereas, methanol and CO yields were 0.52gMeOH/g-cat.h and 0.33gCO/g-cat.h, respectively.