Spinel Metal Oxide-Alkali Carbonate-Based, Low-Temperature Thermochemical Cycles for Water Splitting and CO_2 Reduction

A manganese oxide-based, thermochemical cycle for water splitting below 1000 °C has recently been reported. The cycle involves the shuttling of Na+ into and out of manganese oxides via the consumption and formation of sodium carbonate, respectively. Here, we explore the combinations of three spinel metal oxides and three alkali carbonates in thermochemical cycles for water splitting and CO_2 reduction. Hydrogen evolution and CO_2 reduction reactions of metal oxides with a given alkali carbonate occur in the following order of decreasing activity: Fe_(3)O_4 > Mn_(3)O_4 > Co_(3)O_4, whereas the reactivity of a given metal oxide with alkali carbonates declines as Li_(2)CO_3 > Na_(2)CO_3 > K_(2)CO_3. While hydrogen evolution and CO_2 reduction reactions occur at a lower temperature on the combinations with the more reactive metal oxide and alkali carbonate, higher thermal reduction temperatures and more difficult alkali ion extractions are observed for the combinations of the more reactive metal oxides and alkali carbonates. Thus, for a thermochemical cycle to be closed at low temperatures, all three reactions of hydrogen evolution (CO_2 reduction), alkali ion extraction, and thermal reduction must proceed within the specified temperature range. Of the systems investigated here, only the Na_(2)CO_3/Mn_(3)O_4 combination satisfies these criteria with a maximum operating temperature (850 °C) below 1000 °C

Synthesis of dawsonites

Alkali metal and ammonium dawsonites can be prepared by a nonaqueous process according to which equimolar quantities of the corresponding hydrogen carbonate and aluminum hydroxide in finely divided state are heated together to a tempeature within the range of 150 to 250 C, for a period of 1 to 6 hours under a carbon dioxide pressure within the range of 120 to 360 psig. Carbonates may be used instead of hydrogencarbonates

Investigation of Electrochemistry of High Energy Compounds in Organic Electrolytes. Bibliography on Propylene Carbonate, Gamma- Butyrolactone, and Related Subjects Supplement to Third Progress Report

Bibliography on electrochemistry of high energy compounds in organic electrolyte

Alkali metal carbon dioxide electrochemical system for energy storage and/or conversion of carbon dioxide to oxygen

An alkali metal, such as lithium, is the anodic reactant; carbon dioxide or a mixture of carbon dioxide and carbon monoxide is the cathodic reactant; and carbonate of the alkali metal is the electrolyte in an electrochemical cell for the storage and delivery of electrical energy. Additionally, alkali metal-carbon dioxide battery systems include a plurality of such electrochemical cells. Gold is a preferred catalyst for reducing the carbon dioxide at the cathode. The fuel cell of the invention produces electrochemical energy through the use of an anodic reactant which is extremely energetic and light, and a cathodic reactant which can be extracted from its environment and therefore exacts no transportation penalty. The invention is, therefore, especially useful in extraterrestrial environments

Precipitated K-promoted Co-Mn-Al mixed oxides for direct NO decomposition: Preparation and properties

Direct decomposition of nitric oxide (NO) proceeds over Co-Mn-Al mixed oxides promoted by potassium. In this study, answers to the following questions have been searched: Do the properties of the K-promoted Co-Mn-Al catalysts prepared by different methods differ from each other? The K-precipitated Co-Mn-Al oxide catalysts were prepared by the precipitation of metal nitrates with a solution of K2CO3/KOH, followed by the washing of the precipitate to different degrees of residual K amounts, and by cthe alcination of the precursors at 500 degrees C. The properties of the prepared catalysts were compared with those of the best catalyst prepared by the K-impregnation of a wet cake of Co-Mn-Al oxide precursors. The solids were characterized by chemical analysis, DTG, XRD, N-2 physisorption, FTIR, temperature programmed reduction (H-2-TPR), temperature programmed CO2 desorption (CO2-TPD), X-ray photoelectron spectrometry (XPS), and the species-resolved thermal alkali desorption method (SR-TAD). The washing of the K-precipitated cake resulted in decreasing the K amount in the solid, which affected the basicity, reducibility, and non-linearly catalytic activity in NO decomposition. The highest activity was found at ca 8 wt.% of K, while that of the best K-impregnated wet cake catalyst was at about 2 wt.% of K. The optimization of the cake washing conditions led to a higher catalytic activity.Web of Science97art. no. 59

HIGH TEMPERATURE IR-SPECTROSCOPY OF LITHIUM, SODIUM AND POTASSIUM URANATES

Alkali metal uranates (M4UO5, M2UO4, M2U2O7 and M2U3O10, M = Li, Na, K) were pre-pared by reacting triuranium octaoxide with the corresponding alkali metal carbonates. IR spectra of the uranates were recorded in the temperature range of 25–700 oC

Are spherulitic lacustrine carbonates an expression of large-scale mineral carbonation? : A case study from the East Kirkton Limestone, Scotland

BP Exploration Co. is thanked for funding, and particularly the Carbonate Team for supporting this research and for fruitful discussions. West Lothian Council and Scottish Natural Heritage are thanked for allowing access and permission for sampling the site. The Core Store Team at BGS Keyworth is particularly acknowledged for their assistance. Mark Anderson, Tony Sinclair (University of Hull), and Bouk Lacet (VU University Amsterdam) are thanked for technical support. Anne Kelly (SUERC) for carrying out the Strontium Isotope analyses. Mark Tyrer is thanked for his advice on PHREEQC modelling.Peer reviewedPostprin

Formation of Na2SO4 and K2SO4 in flames doped with sulfur and alkali chlorides and carbonates

High pressure, free-jet expansion, mass spectrometric sampling was used to identify directly and to measure reaction products formed in doped methane-oxygen flames. Flames were doped with SO2 or CH3SH and sodium or potassium chlorides or carbonates. Gaseous NA2SO4 or K2S04 molecules were formed in residence times on the order of msec for each combination of dopants used. Composition profiles of combustion products were measured and compared with equilibrium thermodynamic calculations of product composition