Review of Electrochemical Ammonia Production Technologies and Materials

A comprehensive review of direct carbon fuel cell technology.

Ammonia is one of the most produced chemicals worldwide, and it is not only a major end product but also an important energy storage intermediate. The solid-state electrochemical synthesis of ammonia has the promise to overcome the limitations of the conventional catalytic reactors such as the limited conversion, severe environmental pollution and high energy consumption. Solid-state electrolytes either protonic or oxide ion conductors have been reviewed and particular emphasis is placed on their application to synthesise ammonia. The highest rate of ammonia formation according to the type of electrolyte utilised were in the following order; solid polymers > Ce0.8Gd0.2O2−δ-(Ca3(PO4)2-K3PO4) composites > fluorites > perovskites > pyrochlores although the catalysts in electrodes also play an important role. The highest rate reported so far is found to be 1.13 × 10−8 mol s−1 cm−2 at 80 °C with a potential of 2 V using Nafion membrane, SmFe0.7Cu0.1Ni0.2O3 (SFCN), and Ni-Ce0.8Sm0.2O2−δ as solid electrolyte, cathode and anode, respectively. Synthesising ammonia from steam and N2, by-passing H2 stage offers many advantages such as reduction of device numbers and then the overall costs. The factors affecting the rate of ammonia formation have been discussed as well.

Solid-state electrochemical synthesis of ammonia: a review

https://trisofc.files.wordpress.com/2012/09/recent-developments.pdf

Recent development of ceria-based (nano)composite materials for low temperature ceramic fuel cells and electrolyte-free fuel cells

This review focuses on the use of renewable ammonia for power generation applications and discusses options to convert industrial-grade generators to run on ammonia fuel. The different methods to produce clean ammonia are also discussed in terms of possible advantages and challenges from socio-economic, energetic and environmental perspectives. The main aim of using clean fuel sources, such as ammonia and hydrogen, is to achieve higher sustainability and low carbon emissions compared to conventional fuels. In addition, the present review comparatively assesses and discusses methods for clean ammonia synthesis based on their technical, economic and environmental performance criteria. Numerous potential strategies to improve the clean ammonia production methods are also explored, namely, liquid-electrolyte based systems, composite-membrane based systems, solid-state electrolyte, ceramic/inorganic proton-conducting solid electrolyte based systems, polymer-membrane based systems, O2 conducting-membrane based systems, and molten salt based electrochemical systems. Furthermore, some potential methods to convert various types of commercially available generators to be able to ammonia are proposed and discussed based on the experimental work carried out in the field.

A review on clean ammonia as a potential fuel for power generators

Samarium doped ceria–(Li/Na)2CO3 composite electrolyte and its electrochemical properties in low temperature solid oxide fuel cell

Conductivity of SDC and (Li/Na)2CO3 composite electrolytes in reducing and oxidising atmospheres

Potential low-temperature application and hybrid-ionic conducting property of ceria-carbonate composite electrolytes for solid oxide fuel cells

Proton and Oxygen Ionic Conductivity of Doped Ceria-Carbonate Composite by Modified Wagner Polarization

Composites consisting of Ce0.8Sm0.2O1.9 (SDC)-carbonate were developed as electrolytes for low temperature solid oxide fuel cells (LTSOFC). The SDC power was prepared by sol-gel method. The carbonates were binary eutectics of (Li/Na)2CO3, (Li/K)2CO3 and (K/Na)2CO3. Conductivity measurements showed that the conductivities were depended on the type of carbonates. Discontinuities were found in the Arrhenius plots for both SDC-(Li/Na)2CO3 and SDC-(Li/K)2CO3. For SDC-(Na/K)2CO3 composite electrolyte, the conductivity increased as temperature rose following one slope. Single cells based on various composites were fabricated by a uniaxial die-press method and tested at 450-600 oC. The results showed all cells exhibited improved performances upon that of pure SDC-based cell. The best power density of 532 mW cm-2 at 600 oC was achieved for LTSOFC using composite of SDC and (Li/Na)2CO3. Conductivity mechanism was also discussed.

Jing Di

Papers

Samarium doped ceria–(Li/Na)2CO3 composite electrolyte and its electrochemical properties in low temperature solid oxide fuel cell

Conductivity of SDC and (Li/Na)2CO3 composite electrolytes in reducing and oxidising atmospheres

Potential low-temperature application and hybrid-ionic conducting property of ceria-carbonate composite electrolytes for solid oxide fuel cells

Proton and Oxygen Ionic Conductivity of Doped Ceria-Carbonate Composite by Modified Wagner Polarization

Low temperature solid oxide fuel cells with SDC-carbonate electrolytes