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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ca(CO2)2 by Materials Project

CaC2O4 crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted edge-sharing CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.36–2.50 Å. In the second Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted edge-sharing CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.35–2.49 Å. There are four inequivalent C3+ sites. In the first C3+ site, C3+ is bonded in a bent 120 degrees geometry to two equivalent O2- atoms. Both C–O bond lengths are 1.27 Å. In the second C3+ site, C3+ is bonded in a bent 120 degrees geometry to two equivalent O2- atoms. Both C–O bond lengths are 1.27 Å. In the third C3+ site, C3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. In the fourth C3+ site, C3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ca2+ and one C3+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ca2+ and one C3+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ca2+ and one C3+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ca2+ and one C3+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ca2+ and one C3+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ca2+ and one C3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(CO2)2 by Materials Project

CaC2O4 crystallizes in the monoclinic P2/m space group. The structure is two-dimensional and consists of one CaC2O4 sheet oriented in the (1, 0, 0) direction. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.23–2.56 Å. In the second Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–3.04 Å. There are four inequivalent C3+ sites. In the first C3+ site, C3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.27 Å) C–O bond length. In the second C3+ site, C3+ is bonded in a bent 120 degrees geometry to two equivalent O2- atoms. Both C–O bond lengths are 1.27 Å. In the third C3+ site, C3+ is bonded in a bent 120 degrees geometry to two equivalent O2- atoms. Both C–O bond lengths are 1.27 Å. In the fourth C3+ site, C3+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.33 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Ca2+ and one C3+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one C3+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ca2+ and one C3+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one C3+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ca2+, one C3+, and one O2- atom. The O–O bond length is 1.45 Å. In the sixth O2- site, O2- is bonded in a distorted L-shaped geometry to one Ca2+ and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Microwave-Assisted Hydrogen Generation from Hydrocarbon-Bearing Reservoir Rocks: Stage-Dependent Thermal Runaway and In-Situ Carbonate Engineering

Microwave-assisted hydrogen generation from hydrocarbon-bearing reservoir rocks is strongly influenced by mineralogy, methane activation, carbonate reactions, and thermal runaway behavior. This study investigates a new approach in which carbonate phases are generated in-situ through the reaction of internally produced CO2 with Ca(OH)2 under microwave heating conditions. The objective is to evaluate how rock mineralogy, methane injection, and Ca(OH)2 addition influence hydrogen generation, carbon redistribution, and stage-dependent reaction pathways during microwave exposure. Microwave heating experiments were conducted using Permian Basin reservoir rocks under three experimental conditions: rock-only experiments under Ar atmosphere, CH4–Ar experiments without additive, and CH4–Ar experiments containing 5 wt% Ca(OH)2. Methane-assisted experiments were performed under continuous injection of 30 standard cubic centimeters per minute (sccm) CH4 and 30 sccm Ar. Based on thermal runaway behavior, each experiment was divided into three operational stages: Before Thermal Runaway (BR), After Thermal Runaway–Decrease in Microwave Power (ARD), and After Thermal Runaway– Increase in Microwave Power (ARI). Temperature and gas composition were continuously monitored throughout the experiments. The rock-only experiments demonstrated that hydrogen generation can occur intrinsically from hydrocarbon-bearing rocks under microwave heating, even without externally injected methane. However, hydrogen production did not correlate solely with kerogen content, indicating that mineralogy strongly influences hydrogen-generation pathways. Correlation analyses suggested that kerogen decomposition initially generated CH4, CO, and CO2, followed by secondary hydrocarbon reactions associated with H2 and C2 hydrocarbon formation. Methane-assisted experiments substantially increased hydrogen production; however, identical methane injection rates produced significantly different hydrogen yields among the rock samples, confirming that mineralogical composition controls methaneconversion behavior under microwave heating conditions. The addition of Ca(OH)2 significantly altered carbon evolution behavior in a stage-dependent manner. During the BR stage, Ca(OH)2 reduced gas-phase CO2 production, particularly in carbonate-rich rocks, indicating favorable conditions for in-situ carbonation and carbonate deposition prior to extensive thermal decomposition. The suppression of CO2 during BR became more pronounced with increasing carbonate content of the rock system. After thermal runaway, carbonate-containing systems exhibited enhanced hydrogen generation behavior, suggesting that carbonatederived mineral transformations and carbonate-mediated reactions contribute to high-temperature hydrogen-generation pathways. In carbonate-poor rocks, Ca(OH)2 addition enabled simultaneous URTeC 4493775 2 enhancement of hydrogen production and partial suppression of CO2 release during the post-runaway stages. Overall, the results demonstrate that microwave-assisted hydrogen generation is governed by dynamically evolving interactions among kerogen decomposition, methane activation, mineral transformations, carbonate formation/decomposition, and thermal runaway behavior. This work introduces in-situ carbonate engineering with Ca(OH)2 as a strategy for coupling hydrogen generation with partial insitu carbon management under microwave heating conditions.

03 NATURAL GAS↗
NASA NTRS1983

Improved Oxygen Sources for Breathing Apparatus

Research is described which is directed toward the preparation of chemical oxygen sources which exhibited improved O2 storage and reaction characteristics when compared to potassium superoxide (KO2). The initial focus of the research was the preparation of calcium superoxide (Ca(O2)2) by the disproportionation of calcium peroxide diperoxyhydrate. the Ca(O2)2 was characterized by chemical, thermal, and x ray analyses. Several methods for scaling up the Ca(O2)2 syntheis process were studied. The reactivity of Ca(O2)2 toward humidified carbon dioxide (CO2) was evaluated and was compared to that of KO2 under flow test conditions approximating those existing in portable breathing apparatus. The reactivities of mixtures of KO2 and Ca(O2)2 or lithium peroxide towards humidified CO2 were also studied. Finally, an analysis of two commercial, KO2-based, self contained self rescuers was conducted to determine the potential weight and volume savings which would be possible if Ca(O2)2 or a mixture of KO2 and Ca(O2)2 were used as a replacement for KO2.

Wood, P. C.↗
NASA NTRS1988

Ocean alkalinity and the Cretaceous/Tertiary boundary

A biogeochemical cycle model resolving ocean carbon and alkalinity content is applied to the Maestrichtian and Danian. The model computes oceanic concentrations and distributions of Ca(2+), Mg(2+), and Sigma-CO2. From these values an atmospheric pCO2 value is calculated, which is used to estimate rates of terrestrial weathering of calcite, dolomite, and calcium and magnesium silicates. Metamorphism of carbonate rocks and the subsequent outgassing of CO2 to the atmosphere are parameterized in terms of carbonate rock reservoir sizes, total land area, and a measure of overall tectonic activity, the sea-floor generation rate. The ocean carbon reservoir computed by the model is used with Deep Sea Drilling Project (DSDP) C-13 data to estimate organic detrital fluxes under a variety of ocean mixing rate assumptions. Using Redfield ratios, the biogenic detrital flux estimate is used to partition the ocean carbon and alkalinity reservoirs between the mixed layer and deep ocean. The calcite flux estimate and carbonate ion concentrations are used to determine the rate of biologically mediated CaCO3 titration. Oceanic productivity was severely limited for approximately 500 kyr following the K/T boundary resulting in significant increases in total ocean alkalinity. As productivity returned to the ocean, excess carbon and alkalinity was removed from the ocean as CaCO3. Model runs indicate that this resulted in a transient imbalance in the other direction. Ocean chemistry returned to near-equilibrium by about 64 mybp.

Caldeira, K. G.↗
DOE OSTI2020

Materials Data on CaH2(CO2)2 by Materials Project

CaH2(CO2)2 crystallizes in the tetragonal P4_32_12 space group. The structure is three-dimensional. Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.52 Å. C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.26 Å) and one longer (1.27 Å) C–O bond length. H1+ is bonded in a single-bond geometry to one C2+ atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and one C2+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+ and one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaH2(CO2)2 by Materials Project

CaH2(CO2)2 crystallizes in the tetragonal P4_12_12 space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form distorted corner-sharing CaO6 octahedra. The corner-sharing octahedral tilt angles are 61°. There are a spread of Ca–O bond distances ranging from 2.33–2.52 Å. C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.26 Å) and one longer (1.27 Å) C–O bond length. H1+ is bonded in a single-bond geometry to one C2+ atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to one Ca2+ and one C2+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+ and one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(CoN)2 by Materials Project

Ca(CoN)2 crystallizes in the tetragonal P-4m2 space group. The structure is two-dimensional and consists of one Ca(CoN)2 sheet oriented in the (0, 0, 1) direction. Ca2+ is bonded to four equivalent N3- atoms to form distorted corner-sharing CaN4 tetrahedra. All Ca–N bond lengths are 2.43 Å. Co2+ is bonded in a linear geometry to two equivalent N3- atoms. Both Co–N bond lengths are 1.73 Å. N3- is bonded in a rectangular see-saw-like geometry to two equivalent Ca2+ and two equivalent Co2+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1982

A flow-system comparison of the reactivities of calcium superoxide and potassium superoxide with carbon dioxide and water vapor

A single pass flow system was used to test the reactivity of calcium superoxide with respiratory gases and the performance was compared to that of potassium superoxide. The KO2 system is used by coal miners as a self-contained unit in rescue operations. Particular attention was given to the reactivity with carbon dioxide and water vapor at different temperatures and partial pressures of oxygen, carbon dioxide, and water vapor. The calcium superoxide beds were found to absorb CO2 and H2O vapor, releasing O2. The KO2 bed, however, released O2 at twice the rate of CO2 absorption at 37 C. It is concluded that the calcium superoxide material is not a suitable replacement for the KO2 bed, although Ca(O2)2 may be added to the KO2 bed to enhance the CO2 absorption.

Wood, P. C.↗
DOE OSTI2020

Materials Data on CaCo(SiO3)2 by Materials Project

CaCoSi2O6 is Esseneite structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.79 Å. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent SiO4 tetrahedra and edges with two equivalent CoO6 octahedra. There are a spread of Co–O bond distances ranging from 2.09–2.18 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent CoO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–58°. There are a spread of Si–O bond distances ranging from 1.61–1.70 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ca2+ and two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to one Ca2+, one Co2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two equivalent Co2+, and one Si4+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS2004

Enzymatic Properties of an Alkaline and Chelator Resistant Proportional to alpha-Amylase from the Alkaliphilic Bacillus sp. Isolate L1711

An alkaliphilic amylase producing bacterium, Bacillus sp. strain L1711, was selected among 13 soda lakes isolates. When grown at pH 10.5 and 370 C, strain L1711 produced multiple forms of amylases in the culture broth. One of these, BAA, was purified from the culture supernatant by QAE column chromatography and preparative native gel electrophoresis. The molecular weight of BAA was determined to be 51 kDa by denaturing gel electrophoresis. The pH optima for activity below and above 40 C were 9.5-10.0 and 7.0-7.5 respectively. BAA was stable in the pH range 6-11 and was completely inactivated at 55?C. The thermostability was not increased in the presence of Ca(2+). The enzyme was strongly inhibited by Ca(2+), Zn(2+), Mg(2+), Mn(2+), Ba(2+) and Cu(2+), whereas the presence of Na(+), Co2+ and EDTA (10 mM) enhanced enzymatic activity. The K(sub m) and specific activity of BAA on soluble starch were 1.9 mg/ml and 18.5 U/mg respectively. The main end products of hydrolysis were maltotetraose, maltose and glucose .

Bernhardsdotter, Eva C. M. J.↗
DOE OSTI2020

Materials Data on CaCo2(PO4)2 by Materials Project

CaCo2(PO4)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.30–2.80 Å. In the second Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.79 Å. In the third Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.79 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.30–2.81 Å. There are eight inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to five O2- atoms to form distorted CoO5 trigonal bipyramids that share corners with five PO4 tetrahedra. There are a spread of Co–O bond distances ranging from 2.00–2.15 Å. In the second Co2+ site, Co2+ is bonded to five O2- atoms to form distorted CoO5 trigonal bipyramids that share corners with five PO4 tetrahedra. There are a spread of Co–O bond distances ranging from 1.99–2.13 Å. In the third Co2+ site, Co2+ is bonded to five O2- atoms to form distorted CoO5 trigonal bipyramids that share corners with five PO4 tetrahedra. There are a spread of Co–O bond distances ranging from 2.00–2.15 Å. In the fourth Co2+ site, Co2+ is bonded in a distorted square co-planar geometry to six O2- atoms. There are a spread of Co–O bond distances ranging from 2.02–2.70 Å. In the fifth Co2+ site, Co2+ is bonded to five O2- atoms to form distorted CoO5 trigonal bipyramids that share corners with five PO4 tetrahedra. There are a spread of Co–O bond distances ranging from 1.99–2.15 Å. In the sixth Co2+ site, Co2+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Co–O bond distances ranging from 2.01–2.65 Å. In the seventh Co2+ site, Co2+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Co–O bond distances ranging from 2.01–2.64 Å. In the eighth Co2+ site, Co2+ is bonded in a distorted square co-planar geometry to six O2- atoms. There are a spread of Co–O bond distances ranging from 2.02–2.69 Å. There are eight inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two CoO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.52–1.57 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three CoO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two CoO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.52–1.57 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three CoO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two CoO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.52–1.58 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two CoO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.52–1.58 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three CoO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three CoO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. There are thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Co2+, and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Co2+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Co2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Co2+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Co2+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Co2+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Co2+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Co2+, and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Co2+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Co2+ and one P5+ atom. In the twentieth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the twenty-third O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Co2+, and one P5+ atom. In the twenty-fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Co2+, and one P5+ atom. In the twenty-sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Co2+, and one P5+ atom. In the twenty-seventh O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one P5+ atom. In the twenty-eighth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the twenty-ninth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two Co2+, and one P5+ atom. In the thirtieth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Co2+, and one P5+ atom. In the thirty-first O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Co2+, and one P5+ atom. In the thirty-second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Co2+ and one P5+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS2012

Organic Combustion in the Presence of Ca-Carbonate and Mg-Perchlorate: A Possible Source for the Low Temperature CO2 Release Seen in Mars Phoenix Thermal and Evolved Gas Analyzer Data

Two of the most important discoveries of the Phoenix Lander were the detection of approx.0.6% perchlorate [1] and 3-5% carbonate [2] in landing site soils. The Thermal and Evolved Gas Analyzer (TEGA) instrument on the Phoenix lander could heat samples up to approx.1000 C and monitor evolved gases with a mass spectrometer. TEGA detected a low (approx.350 C) and high (approx.750 C) temperature CO2 release. The high temp release was attributed to the thermal decomposition of Ca-carbonate (calcite). The low temperature CO2 release could be due to desorption of CO2, decomposition of a different carbonate mineral, or the combustion of organic material. A new hypothesis has also been proposed that the low temperature CO2 release could be due to the early breakdown of calcite in the presence of the decomposition products of certain perchlorate salts [3]. We have investigated whether or not this new hypothesis is also compatible with organic combustion. Magnesium perchlorate is stable as Mg(ClO4)2-6H2O on the martian surface [4]. During thermal decomposition, this perchlorate salt releases H2O, Cl2, and O2 gases. The Cl2 can react with water to form HCl which then reacts with calcite, releasing CO2 below the standard thermal decomposition temperature of calcite. However, when using concentrations of perchlorate and calcite similar to what was detected by Phoenix, the ratio of high:low temperature CO2 evolved is much larger in the lab, indicating that although this process might contribute to the low temp CO2 release, it cannot account for all of it. While H2O and Cl2 cause calcite decomposition, the O2 evolved during perchlorate decomposition can lead to the combustion of any reduced carbon present in the sample [5]. We investigate the possible contribution of organic molecules to the low temperature CO2 release seen on Mars.

Archer, Douglas↗
NASA NTRS1990

Mechanistic studies of the CO-oxidation reaction on catalysts for use in long-life CO2 lasers

The catalytic recombination of carbon monoxide and oxygen was studied under conditions expected to be present in a sealed E-beam CO2 laser system. These conditions are typically a gas inlet temperature of 60 C, a substoichiometric CO/O2 ratio of ca. 2.5/1 with an oxygen feed rate of ca. 5 micromoles/s, a carrier gas comprising He, N2 and CO2 in the ratio of 3:2:1, near atmospheric pressure and a gas velocity of 4 m/s. Heterogeneous catalysts, based on precious metal supported on tin oxide, have been coated onto ceramic monoliths and tested for catalytic activity and stability after a reduction/passivation step. Two catalyst systems have been chosen. These are Pt/Pd/SnO2 and Pt/Ru/SnO2. Under the conditions described above, a characteristic decline in catalytic activity is apparent for both systems, and exit gas temperature has been recognized as a sensitive parameter by which to monitor the activity changes. A semilogarithmic plot of exit temperature as a function of time has revealed two distinct processes connected with the decline in activity: one process is associated with reduction of the oxidized precious metal (at Site A), whilst the other is related to the formation and approach to steady-state of an active site at the metal/support interface (Site B).

Dawood, Talat↗
DOE OSTI2020

Materials Data on Ca(CoP)2 by Materials Project

CaCo2P2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ca2+ is bonded in a distorted body-centered cubic geometry to eight equivalent P3- atoms. All Ca–P bond lengths are 3.00 Å. Co2+ is bonded to four equivalent P3- atoms to form a mixture of corner and edge-sharing CoP4 tetrahedra. All Co–P bond lengths are 2.24 Å. P3- is bonded in a 9-coordinate geometry to four equivalent Ca2+, four equivalent Co2+, and one P3- atom. The P–P bond length is 2.51 Å.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Air Revitalization Using Superoxides

Pellets made from powder mixtures of potassium superoxide, KO2, and calcium superoxide, Ca(O2)2, proven markedly superior to pellets of pure KO2 for adding O2 to and removing CO2 from atmospheric-pressure flow of humidified CO2 in He. Superoxides used extensively to supply O2 and scrub CO2 in variety of ambient-pressure life-support applications, including portable self-contained breathing apparatuses, spacecraft, and undersea submersible craft.

Wydeven, Theodore↗
NASA NTRS1984

Changes in the High-latitude Ocean as Possible Causes of Atmospheric CO2 Variations

Measurements on air enclosed in old polar ice have indicated that the atmospheric CO2 concentration was ca. 50 to 70 ppm lower in late glacial times than during the Holocene. Similar measurements performed on samples from a Greenland ice core, dating ca. 30,000 to 40,000 B.P., and have yielded evidence of several CO2 oscillations with an amplitude of ca. 50 ppm. Each change lasted on the order of a few centuries. A mechanism by which circulation changes in the high-latitude ocean could lead to rapid variations in atmospheric CO2 is proposed. In the Antarctic Ocean a slowing down of the vertical mixing would imply a smaller upward flux of sigma CO2 and nutrients. Assuming constant productivity, sigma CO2 and nutrients would be more completely used which would imply lower CO2 in these high-latitude surface waters. In areas with a warm surface, a slowing down of the circulation would not have a direct impact on CO2 because productivity would automatically decrease by the same factor as the upwelling rate of nutrients. Studies with a simple box model of the ocean-atmosphere system suggest that a suddent decrease by a factor of 2 of the water exchange between the surface and deep sea in high latitudes could lead to a CO2 decrease of ca. 40 to 50 ppm with a time constant of ca. 200 years. Deep-sea sediment studies indicate rapid changes in the high-latitude surface conditions of the North Atlantic and the Antarctic Oceans at the end of the last glaciation. Studies of carbon isotope ratios should help ascertain whether this proposed mechanism was indeed responsible for the CO2 variation.

Siegenthaler, U.↗