The effect of the alkali additive on the highly active Ru/C catalyst for water gas shift reaction

Abstract

The present study reported the results on the water–gas shift (WGS) reaction over a series of Ru/C catalysts. It was found that the reduction method showed a remarkable effect on the catalytic activity of Ru/C catalysts over WGS reaction, which increased in an order of the reduction by NaBH₄, ethylene glycol, H₂. It has been shown that alkali additives with K₂CO₃ significantly improved the activity of the Ru/C catalysts. XPS results indicated that Ru species were further oxidized by the addition of K₂CO₃, which indicated an electron transfer from the alkali metal to the substrate, resulting in stronger bonding of the adsorbed gas. FTIR results showed that the absorption peak intensity of H₂O and hydroxyl group increased with the increase of K₂CO₃ content, due to the strong hygroscopic ability of K₂CO₃. Through the addition of K₂CO₃ to the Ru/C catalyst, much more water was adsorbed around the catalytic active sites, reducing the strong adsorption of CO on the active sites. Thus the addition of K₂CO₃ balanced the concentration of water and CO on the active sites, which was considered to be the key step for low temperature WGS reaction over Ru supported on irreducible activated carbon.