Preparation of Ag–Cu/Al₂O₃ Composite Catalyst for Ammonia Decomposition

Abstract

A catalyst of Ag with alumina has been widely used for the decomposition of odorous ammonia. In order to meet cost effectiveness, copper was added with five different doping ratios of Ag/Cu in this work, and NH 3 decomposition was examined at 150-400 C. Experimental results show that the catalyst doped with only Cu shows very weak potential to oxidize NH 3 despite its excellent selectivity for nitrogen molecules than NO or N 2 O at temperatures over 300 C. Analysis by X-ray photoelectron spectroscopy indicates that Ag 0 is the major chemical functionality that determines the decomposition rate of NH 3 at low temperature, e.g., 200 C, while Ag + and Ag 2+ are efficient at higher temperatures. Among the five segregated copper functionalities, only Cu 2p a/2 appeared to be favorable for the activity of Ag particles. It was found from the experimental results that Ag/Cu = 1:9 could provide a cost-effective combination for the low temperature regime.

Delafossite Ag2CuMnO4 is a Novel Catalytic Material for Low‐Temperature Oxidation of CO and NH3

“…Delafossite Ag 2 CuMnO 4 can be considered as Ag‐modified hopcalite explaining the interest for the study of its catalytic properties in CO oxidation under ambient conditions. Note that silver‐copper mixed systems are widely studied as potential catalysts for the reaction of selective ammonia oxidation, [32–35] that is important for the removal of NH 3 from exhausts of diesel engines, power plants, and industrial manufactures. The synergism between silver and copper provides both high activity and high N 2 selectivity at relatively low temperatures, [32] which highlights the interest in the study of mixed oxide Ag 2 CuMnO 4 as a potential catalyst for NH 3 oxidation.…”

Supported binary CuOx–Pt catalysts with high activity and thermal stability for the combustion of NH3 as a carbon-free energy source

“…On the other hand, binary systems comprising supported CuO x –Ag, 5 CuO x –Pt, 6 CuO x –Au, 7 CuO x –CeO 2 8 and –Li 2 O 3 8 catalysts exhibiting a high performance for the selective catalytic oxidation of NH 3 (NH 3 -SCO) have been previously reported. In particular, CuO x –Pt systems are expected to exhibit high thermal stability because of the high melting point of Pt (∼1770 °C).…”

Local Structures and Catalytic Ammonia Combustion Properties of Copper Oxides and Silver Supported on Aluminum Oxides

“…Moreover, Chmielarz and Jablonska also reviewed the effective catalysts for the selective oxidation of NH 3 emission on automotive and energy production sectors . For the selective catalytic reduction of NO by NH 3 , novel CuO x -based catalysts were also recently reported. − However, binary systems comprising CuO x and other materials, e.g., CuO x –Ag, − −Pt, − −Au, and −CeO 2 (−Li 2 O 3 ), supported on Al 2 O 3 catalysts have been previously reported to exhibit high performances for catalytic NH 3 oxidation to N 2 . Among the Al 2 O 3 -supprted binary CuO x –metal and/or −oxides systems, CuO x –Ag/Al 2 O 3 exhibits particularly high NH 3 oxidation activity and N 2 selectivity.…”

“…A similar coimpregnated CuO x –Ag/Al 2 O 3 was also prepared by Yang et al, who studied the production profiles and adsorption species of the catalyst for NH 3 oxidation . More recently, Lee et al also reported that the catalytic NH 3 oxidation properties of CuO x –Ag/Al 2 O 3 . However, these published studies regarded NH 3 as air pollution; therefore, their NH 3 oxidation tests were evaluated at low reaction temperatures of less than approximately 400 °C.…”

“…14 More recently, Lee et al also reported that the catalytic NH 3 oxidation properties of CuO x −Ag/Al 2 O 3 . 15 However, these published studies regarded NH 3 as air pollution; therefore, their NH 3 oxidation tests were evaluated at low reaction temperatures of less than approximately 400 °C.…”