Samaria-doped ceria Ce 0.8 Sm 0.2 O 2−δ (SDC) and SmFe 0.7 Cu 0.3−x Ni x O 3 have been synthesized by the sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The electrochemical synthesis of ammonia was investigated at atmospheric pressure and low temperature, using the SFCN materials as the cathode, a Nafion membrane as the electrolyte, nickel-doped SDC (Ni-SDC) as the anode and silver-platinum paste as the current collector. Ammonia was synthesized from 25 to 100℃ when the SFCN materials were used as cathode, with SmFe 0.7 Cu 0.1 Ni 0.2 O 3 giving the highest rates of ammonia formation. The maximum rate of evolution of ammonia was 1.13 × 10 −8 mol·cm −2 ·s −1 at 80℃, and the current efficiency reached as high as 90.4%. electrochemical synthesis of ammonia, ammonia synthesis at atmospheric pressure and low temperature, Nafion membrane, metal oxide

Polysulfone (PSF) and sulfonated polysulfone (SPSF) were synthesized and characterized by IR spectrum. Sm 1.5 Sr 0.5 NiO 4 (SSN) and Ni-Ce 0.8 Sm 0.2 O 2-δ (Ni-SDC, Ni-samarium doped ceria) were prepared and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ammonia was synthesized from wet hydrogen and dry nitrogen with applied voltage, using SSN as cathode, Ni-SDC as anode, Nafion and SPSF as proton membrane respectively. The performances of Nafion and SPSF membranes in ammonia synthesis were investigated and compared at atmospheric pressure and low temperature (25-100 ℃). The results demonstrated that the proton conducting performances of Nafion and SPSF membranes were similar and the highest rates of evolution of ammonia were up to 1.05×10 -8 and 1.03×10 -8 mol•cm -2 •s -1 respectively at 80 and 2.5 ℃ V.

Sm 1.5 Sr 0.5 MO 4 (M＝Ni, Co, Fe) (SSM) catalysts were prepared by a sol-gel method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ammonia was synthesized from wet hydrogen and dry nitrogen at atmospheric pressure and low temperature ℃ with applied voltage, using SSM as a cathode, Ni-Ce 0.8 Sm 0.2 O 2-δ (Ni-SDC) as an anode, and silver-platinum film as a current collector, Nafion proton exchange membrane as a proton permeating membrane. Several important factors on ammonia synthesis were investigated and the optimal synthetic temperature was found, at which the highest rate of evolution of ammonia was up to 1.05×10Keywords Nafion membrane, Sm 1.5 Sr 0.5 MO 4 (SSM), wet hydrogen, ammonia synthesis at atmospheric pressure and low temperatureIt is well known that ammonia is not only a material of producing (NH 4 ) 2 SO 4 , NH 4 NO 3 , NH 4 HCO 3 and carbamide, but also an important material of synthesizing HNO 3 , coloring matter, detonator, medicament, organics, plastics, fibre and so on. So the ammonia synthesizing industry plays an important role in the national economy.At present, the traditional method for ammonia synthesis is Haber's process, however, there are many defects in Haber's process, such as high energy consumption, severe environmental pollution and stern requirement for the equipment. With the increasing demand of ammonia all over the world and the increasing problems of energy sources and environment pollution, many methods of ammonia synthesis appeared. Panagos and Stoukides 1 put forward high temperature proton conduction (HTPC) to synthesize ammonia in 1996, which showed the application prospect of ammonia synthesis. Marnellos and Stoukides 2 synthesized ammonia using HTPC, by which the rate of evolution of ammonia was up to 10 -11 mol•cm -2 •s -1 . Our laboratory has worked a lot on HTPC to electrosynthesize ammonia and the rate of evolution of ammonia was up to 10It realized the ammonia synthesis at atmosphere pressure and reduced the stern requirement for the equipment, but the disadvantage is high energy consumption because of higher temperature. It will be an energy saving and environmental pollution reducing method to synthesize ammonia at low temperature and atmospheric pressure.The polymer proton exchange membrane (PEM) is a proton selective conductor at low temperature (lower than 120 commonly) and ℃ an insulator to electron.Nafion membrane is recognized as the best polymer proton exchange membrane, which has excellent capability of mechanics and chemistry. In this paper, Sm Preparation and characterizationPreparation of SSM and Ni-SDC Sm 1.5 Sr 0.5 NiO 4 (SSN) catalyst was prepared by a citrate sol-gel method. Calculated amounts of Sr(NO 3 ) 2 and Ni(NO 3 ) 2 were dissolved in distilled water and Sm 2 O 3 was dissolved in concentrated HNO 3 , then the solutions were commixed. Solid citric acid was added to the solution and stirred until completely dissolved, resulting in the molar ratio of citric acid/metal＝2∶1. The pH value of the solution shou...

Catalysts H 2000Sm1.5Sr0.5MO4 (M: Ni, Co, Fe) Cathode Catalysts for Ammonia Synthesis at Atmospheric Pressure and Low Temperature. -The title catalysts are prepared by a sol-gel method from HNO3 solutions of M(NO3)2 (M: Sr, Ni, Co, Fe), Sm2O3, and citric acid. The resulting solid mass is calcined at 700°C for 4 h followed by sintering for 4 h at 1150°C. The samples are characterized by XRD and SEM. The Ni-containing compound is a better catalyst for electrochemical NH3 synthesis from H2 and N2 at atmospheric pressure and low temperature (25-100°C) than the Co-and Fe-containing samples. The highest rate of NH3 evolution is up to 1.05 x 10 -8 mol/(cm 2 s) using Sm1.5Sr0.5NiO4 as the cathode at 80°C. -(XU, G.; LIU*, R.; Chin.