The abrupt and massive deactivation of methane dry reforming catalysts especially Ni-based is still a monumental impediment towards its industrialization and commercialization for production of value-added syngas via Fischer-Tropsch process. The need for further and more critical understanding of inherent and tailored interactions of catalyst components for performance and stability enhancement during reforming reaction cannot be over-emphasized. This review provides a contemporary assessment of progresses recorded on synergistic interplay among catalyst components (active metals, support, promoters and binders) during dry reforming using state-of-the-art experimental and theoretical techniques. Advancements achieved during interplay leading to improvements in properties of existing catalysts and discovery of novel ones were stated and expatiated. Reaction pathways, catalytic activities, selection of appropriate synthesis route and metal/support deactivation via sintering or carbon deposition have over time been successfully studied and explained using information from these crucial component interactions. This perspective describes the roles of these interactions and their applications towards development of robust catalysts configurations for successful industrial applications.

A review on catalyst development for dry reforming of methane to syngas: Recent advances

Powder metallurgy (PM) of titanium is a potentially cost-effective alternative to conventional wrought titanium. This article examines both traditional and emerging technologies, including the prod...

https://www.tandfonline.com/doi/pdf/10.1080/09506608.2017.1366003

Powder metallurgy of titanium – past, present, and future

Solid electrode processes fall in the central focus of electrochemistry due to their broad-based applications in electrochemical energy storage/conversion devices, sensors and electrochemical preparation. The electrolytic production of metals, alloys, semiconductors and oxides via the electrochemical reduction of solid compounds (especially solid oxides) in high temperature molten salts has been well demonstrated to be an effective and environmentally friendly process for refractory metal extraction, functional materials preparation as well as spent fuel reprocessing. The (electro)chemical reduction of solid compounds under cathodic polarizations generally accompanies a variety of changes at the cathode/melt electrochemical interface which result in diverse electrolytic products with different compositions, morphologies and microstructures. This report summarizes various (electro)chemical reactions taking place at the compound cathode/melt interface during the electrochemical reduction of solid compounds in molten salts, which mainly include: (1) the direct electro-deoxidation of solid oxides; (2) the deposition of the active metal together with the electrochemical reduction of solid oxides; (3) the electro-inclusion of cations from molten salts; (4) the dissolution–electrodeposition process, and (5) the electron hopping process and carbon deposition with the utilization of carbon-based anodes. The implications of the forenamed cathodic reactions on the energy efficiency, chemical compositions and microstructures of the electrolytic products are also discussed. We hope that a comprehensive understanding of the cathodic processes during the electrochemical reduction of solid compounds in molten salts could form a basis for developing a clean, energy efficient and affordable production process for advanced/engineering materials.

The electrochemical reduction processes of solid compounds in high temperature molten salts

DFT study of adsorption behavior of NO, CO, NO2, and NH3 molecules on graphene-like BC3: A search for highly sensitive molecular sensor

1. Introduction 28632. Theoretical Considerations 28643. Electro-deoxidation under Controlled Voltage orPotential 28663.1. Earlier Attempts to Describe the ReductionMechanism 28663.2. Three-Phase Interline (3PI) PropagationModels 28673.3. Alkali Ternary Oxides Intermediates 28673.3.1. Niobium Oxide 28673.3.2. Tantalum Oxide 28683.3.3. Chromium Oxide 28683.3.4. Titanium Oxide 28683.3.5. Zirconium Oxide 28703.3.6. Tungsten Oxide 28703.3.7. Aluminum Oxide 28703.4. Electro-deoxidation of Mixed Oxides andOxide Solid Solutions 28713.5. Attempts to Use Inert Anode 28734. Cyclic Voltammetry 28744.1. Understanding the Cathodic ReductionReactions 28744.2. Determining the Optimum Operation Po-tential 28764.3. Exploring the Surface Phenomenon 28774.4. Studying the Complex Side Processes andDetecting the High Temperature Intermedi-ate Phases 28774.5. Providing Direct Insights into the Kinetics ofElectrode Reactions 28785. Electro-deoxidation under Constant CurrentChronopotentiometry 28796. Summary and Future Direction 2882Author Information 2883Corresponding Author 2883Notes 2883Biographies 2883References 2884

DC Voltammetry of Electro-deoxidation of Solid Oxides

Judicious selection of mixed ionic–electronic conducting (MIEC) perovskite oxide as oxygen transport membrane (OTM) offers the potential to enhance overall process economics and systems performance for a wide variety of industrial applications ranging from clean and efficient energy conversion (oxy-combustion) to selective gas separation (high purity oxygen production) and value added chemicals (syngas and liquid fuel) production with near-zero greenhouse gas emissions. Doped lanthanum chromite perovskites have been considered as promising material of choice for oxygen transport membrane (OTM) due to their superior thermo-chemical stability in aggressive environment (800–1000 °C, 0.21–10−20 P O 2 ) than the other mixed ionic–electronic conducting (MIEC) perovskites such as ferrites and cobaltite's. Thermo-physical properties of the lanthanum chromite, required for optimum oxygen transport can be tuned by modifying the crystal structure, chemical bonding, and ionic and electronic transport properties through selection of dopant's type and level. A perspective on the development of lanthanum chromite-based oxygen transport membranes is presented with an insight based on the pertinent literature and data analysis. The role of various A- and B-site dopants on the crystal structure, densification, thermal expansion, electrical transport, oxygen permeation, mechanical properties, and thermochemical stability of lanthanum chromite is discussed to enlighten ‘composition–structure–property’ correlations. It has been found that: the preferred dopants are strontium at A-site and manganese, nickel, iron, and titanium at B-site to obtain the desired thermo–chemo–electro–mechano properties. Challenges for long term performance and structural stability of doped lanthanum chromite as an oxygen transport membrane are outlined for the applications under ‘real system’ exposure conditions.

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Lanthanum chromite based perovskites for oxygen transport membrane

Easy-to-use mullite and spinel sols as bonding agents in a high-alumina based ultra low cement castable

Phase relations in the system Ca-Ti-O have been established by equilibration of several samples at 1200 K for prolonged periods and identification of phases in quenched samples by optical and scanning electron microscopy, XRD and EDS. Samples representing 20 compositions in the ternary system were analyzed. There was negligible solid solubility of Ca in the phases along the binary Ti-O, and of Ti in CaO. Four ternary oxides were identified: CaTiO3, Ca4Ti3O10 and Ca3Ti2O7 containing tetravalent titanium, and CaTi2O4 containing trivalent titanium. Tie-lines link calcium titanite (CaTi2O4) with the three calcium titanates (CaTiO3, Ca4Ti3O10 and Ca3Ti2O7), CaO, oxygen excess TiO1+delta and stoichiometric TiO. Tie-lines connect CaTiO3 with TiO2-x, Magneli phases TinO2n-1 (28 >= n >= 4), Ti3O5, Ti2O3 and TiO1+delta. CaO was found to coexist with TiO, and Ti-O solid solutions alpha and beta. The phase diagram is useful for understanding the mechanisms and kinetics of direct calciothermic reduction of TiO2 to metal and electrochemical reduction of TiO2 using graphite anode and molten CaCl2 electrolyte.

/pdf/phase-diagram-of-the-system-ca-ti-o-at-1200-k-46k3ph4rhc.pdf

Phase diagram of the system Ca-Ti-O at 1200 K

Phase transformation, thermal expansion and electrical conductivity of lanthanum chromite

Calciothermic reduction of TiO2 provides a potentially low-cost route to titanium production. Presented in this article is a suitably designed diagram, useful for assessing the degree of reduction of TiO2 and residual oxygen contamination in metal as a function of reduction temperature and other process parameters. The oxygen chemical potential diagram a la Ellingham-Richardson-Jeffes is useful for visualization of the thermodynamics of reduction reactions at high temperatures. Although traditionally the diagram depicts oxygen potentials corresponding to the oxidation of different metals to their corresponding oxides or of lower oxides to higher oxides, oxygen potentials associated with solution phases at constant composition can be readily superimposed. The usefulness of the diagram for an insightful analysis of calciothermic reduction, either direct or through an electrochemical process, is discussed. Identified are possible process variations, modeling and optimization strategies.

Sapna Gupta

Papers

Lanthanum chromite based perovskites for oxygen transport membrane

Easy-to-use mullite and spinel sols as bonding agents in a high-alumina based ultra low cement castable

Phase diagram of the system Ca-Ti-O at 1200 K

Phase transformation, thermal expansion and electrical conductivity of lanthanum chromite

Calciothermic reduction of TiO2: A diagrammatic assessment of the thermodynamic limit of deoxidation