Effects of preparation method and precipitant on Mn–Ga oxide in combination with SAPO-34 for syngas conversion into light olefins

Abstract

Because metal oxides play an important role in the adsorption and activation of CO and H₂, binary Mn–Ga metal oxides were prepared and combined with SAPO-34 to study its catalytic performance for syngas conversion into light olefins. The effects of preparation method and precipitant on the Mn–Ga oxides were investigated. The co-precipitated Mn–Ga oxide sample exhibits a higher activity and light olefins selectivity than impregnated Ga/MnO_x and Mn/Ga₂O₃, or the powder mixed MG-(PM), or the solution precursor mixed MG-(SM) samples. For the precipitants, viz., ammonia hydroxide (AH), sodium hydroxide (SH), oxalic acid (OA) and sodium carbonate (SC), the prepared MG-AH and MG-SH oxides exhibit an amorphous structure, strong interaction between the Mn and Ga species and a high concentration of oxygen vacancies. Furthermore, MG-AH possesses the largest amount of desorbed CO and moderate H₂ dissociation. Thus, the MG-AH combined with SAPO-34 exhibits the highest CO conversion of 19.5% and the light olefins space-time yield of 116.1 mL h⁻¹ g⁻¹ with a stable activity in a reaction time of 50 h.