NH3 production from absorbed NO with synergistic catalysis of Pd/C and functionalized ionic liquids

Abstract

To reduce the emission of NO from fossil fuel combustion and the energy consumption associated with NH₃ production, the development of simple and efficient methods to transform NO into high-value-added NH₃ is essential. Here, we report the efficient catalytic hydrogenation of NO to NH₃ under mild reaction conditions by the synergistic catalysis of functionalized ionic liquids (FILs) and Pd catalysts. In this system, an FIL [TEPA][Im] acted as both an absorbent and a catalyst. The presence of [TEPA][Im] enhanced the catalytic performance by changing the coordination and electronic environment of Pd on the Pd/C catalyst. First, NO was absorbed by [TEPA][Im]; then, the hydrogenation of absorbed NO to NH₃ was performed at a low temperature via the synergistic catalyzation of [TEPA][Im] and Pd/C. The effects of various factors on NO hydrogenation to NH₃ were also investigated. Remarkably, Pd/C exhibited outstanding properties in the formation of NH₃ with a high yield of 67% in the FIL [TEPA][Im] under the conditions of 100 °C and an H₂ pressure of 0.5 MPa. [TEPA][Im] could be reused multiple times and the product NH₃ could be recovered by flashing.