Decomposition Of Carbon Dioxide Research Articles

Inverted Temperature Dependence of the Decomposition of Carbon Dioxide on Oxide-Supported Polycrystalline Copper

The paper reports an investigation of the decomposition of carbon dioxide on an industrial (I.C.I.) methanol synthesis catalyst, which in effect is oxide-supported polycrystalline copper. In the temperature range 173 to 333 K using the technique of reactive frontal chromatography it is shown that (i) the rate of decomposition of carbon dioxide increases on decreasing the dosing temperature, and (ii) the extent of oxidation of copper by the decomposition of carbon dioxide increases on decreasing the dosing temperature. The former result is in agreement with an earlier conclusion that carbon dioxide decomposition on unsupported polycrystalline copper was precursor-state moderated. The "negative" activation energy obtained is in fact the difference in energy between the heat of adsorption of the precursor state and the surface decomposition activation energy of the adsorbed precursor state, which is the same argument as that used by G. Ertl [ in "Catalytic Ammonia Synthesis" (J. R. Jennings, Ed.), p. 123, Plenum, New York, 1991] to explain the negative activation energy for the nitrogen sticking probability on potassium-promoted single crystal iron. The inverted temperature dependence of the extent of the oxidation of copper by the decomposition of carbon dioxide is rationalised on the basis that the oxided copper surface reconstructs in an activated way to an unreactive state. The energy barrier to that reconstruction is too high for it to occur at 173 K (the lowest temperature studied) where the extent of surface oxidation (25% of a monolayer) is therefore solely a function of oxygen poisoning of the reactive surface. The CO/CO 2 reactive frontal lineshape at 173 K is exactly the same as that of the N 2/N 2O lineshape at 333 K; the fewer oxygen coverage at cessation of reaction by oxygen poisoning for the CO/CO 2 reaction shows the reaction to be structure sensitive. Infrared spectroscopic data show the reconstruction to involve the loss of the (110) face and the growth of the (211) face while CO desorption data confirm the activated nature of the reconstruction.

Decomposition of carbon dioxide to carbon by hydrogen-reduced Ni(II)-bearing ferrite

Hydrogen-activated Ni(II)-bearing ferrite, Ni 0.37 2+ Fe 0.49 2+ Fe 2.09 3+ O4.00, showed a high rate of decomposition of carbon dioxide to carbon at 300°C. This is based on the redox process of the Ni(II)-bearing ferrite with the spinel type of crystal structure. The rates of both activation by hydrogen gas and oxidation in carbon dioxide gas were much improved in the Ni (II)-bearing ferrite. The rate of decomposition was 0.178 mol h−1 for the activated Ni(II)-bearing ferrite and 0.005 92 mol h−1 for the activated magnetite in the batch mode, being 30 times larger. The rate of carbon dioxide decomposition was 16 times higher in the flow system in comparison with that of the activated magnetite.

Molecular fragmentation patterns of carbon dioxide at very high internal energies

AbstractIon–ion coincidence measurements following K‐shell absorption in the carbon dioxide molecule were performed by applying time‐of‐flight mass spectrometry in conjunction with monochromatic synchrotron radiation and electron impact. Identification of particularly sensitive electronic transitions and the consecutive molecular fragmentation in real time was performed. Analysis of coincidence recordings from decomposition of carbon dioxide reveals one distinct pathway in which three cations are formed following excitation of oxygen Is electrons.

Carbon dioxide decomposition into carbon with the rhodium-bearing magnetite activated by H2-reduction

The CO2 decomposition into carbon with the rhodium-bearing activated magnetite (Rh-AM) was studied in comparison with the activated magnetite (AM). The Rh-AM and the AM were prepared by flowing hydrogen gas through the rhodium-bearing magnetite (Rh-M) and the magnetite (M), respectively. The rate of activation of the Rh-M to the Rh-AM was about three times higher than that of the M to the AM at 300 °C. The reactivity for the CO2 decomposition into carbon with the Rh-AM (70% CO2 was decomposed in 40 min) was higher than that with the AM (30% in 40 min) at 300 °C. The Rh-M was activated to the Rh-AM at a lower temperature of 250 °C, and the Rh-AM decomposed CO2 into carbon at 250 °C. On the other hand, the M was little activated at 250 °C.

Decomposition of Carbon Dioxide to Carbon with Active Wustite at 300°C

Active wustite (FeδO, with a δ value of 0.98) was prepared by keeping normal wustite (δ value of 0.94) in a N2 atmosphere at 300°C for 10 min. This reaction is given by (4δ2–3)Feδ1O→(4δ1–3)Feδ2O + (δ2–δ1)Fe3O4 where δ1= 0.94 and δ2= 0.98. The equation indicates that the normal wustite undergoes eutectoid decomposition into active wustite and stoichiometric magnetite (Fe3O4). Carbon dioxide (1.013 × 105 Pa) was almost completely (100%) decomposed into carbon (zero valence) by the active wustite at the low temperature of 300°C, which was associated with the transformation of the active wustite into the stoichiometric magnetite. The internal pressure of the reaction cell eventually became a vacuum.

Interaction of carbon dioxide and oxygen on iron films at 273 K

Coadsorption of carbon dioxide and oxygen on polycrystalline iron films at 273 K has been studied by means of measurements of adsorption isotherms, differential heats of adsorption, changes in resistance, thermal desorption and isotopic exchange. This coadsorption system proves to be rather complicated. The coadsorption effects strongly depend on the sequence of the adsorption of the two gases. Preadsorbed oxygen blocks part of the surface for adsorption and decomposition of carbon dioxide. Oxygen admitted to samples with already adsorbed carbon dioxide is able to displace both CO 2 and its decomposition product CO. In the absence of oxygen there are two desorption peaks for CO 2 (about 330 K and about 390 K) and two for the decomposition product CO (about 400 K and > 650 K). The peaks at 390 K and > 650 K are due to CO-O and C-O recombination, respectively, as can be deduced from isotopic exchange. Coadsorption of the two gases influences the positions and the heights of the desorption peaks.

The adsorption and decomposition of carbon dioxide on polycrystalline copper

The interaction of carbon dioxide with polycrystalline copper has been studied by radiolabelling techniques using {14-C} carbon dioxide, and by temperature programmed desorption. It is showninter alia, that: carbon dioxide is weakly adsorbed at the clean surface; that this acts as precursor which, on activation, produces adsorbed carbon monoxide and surface oxygen; and that this oxidised copper surface then adsorbs carbon dioxide more strongly yielding a state which can be hydrogenated first to formate, and thereafter to methanol.

Thermal decomposition of carbon dioxide in an argon plasma jet

The decomposition of carbon dioxide to carbon monoxide and oxygen in an argon plasma is studied. The overall kinetic and energy-related parameters of the process, as well as the quenching rates of the products, are evaluated on the basis of measured radial and longitudinal profiles of both temperature and degree of decomposition in the high-temperature reaction zone.

Studies on the Decomposition of Carbon Dioxide in a Low‐Temperature Plasma

AbstractThe decomposition of carbon dioxide was studied in an argon plasma jet, generated by a direct‐current arc discharge. The decomposition degree of carbon dioxide was up to 0,4 at an effective energy consumption lower than 1 MJ/mole CO. The efficiency of high‐temperature decomposition of carbon dioxide to carbon monoxide and oxygen is essentially dependent both on the quenching intensity of the products, which prevents from the reverse oxidation reaction in the system, as well as on the proper conditions of plasma‐substrate mixing.

Catalytic Processes in the Atmospheres of Earth and Venus

Photochemical processes in planetary atmospheres are strongly influenced by catalytic effects of minor constituents. Catalytic cycles in the atmospheres of Earth and Venus are closely related. For example, chlorine oxides (CIOx) act as catalysts in the two atmospheres. On Earth, they serve to convert odd oxygen (atomic oxygen and ozone) to molecular oxygen. On Venus they have a similar effect, but in addition they accelerate the reactions of atomic and molecular oxygen with carbon monoxide. The latter process occurs by a unique combination of CIOx catalysis and sulfur dioxide photosensitization. The mechanism provides an explanation for the very low extent of carbon dioxide decomposition by sunlight in the Venus atmosphere.

The thermal decomposition of carbon dioxide

A thermodynamic study has been made of the thermal decomposition of carbon dioxide by calculating the equilibrium concentrations of the decomposition products as a function of temperature and total pressure. It was found that over a fairly wide range of temperature and pressure, CO 2 dissociates into carbon monoxide and oxygen with no precipitation of carbon. At each total pressure, above a certain critical temperature, the carbon monoxide disproportionates and the decomposition products are carbon oxygen.

A plasmochemical concept for thermochemical hydrogen production

This paper discusses plasmochemical methods of water decomposition to produce hydrogen. Both the direct decomposition of water and a cycle involving the decomposition of carbon dioxide are discussed. A comparison of the relative merits of several methods of hydrogen production using a nuclear energy source is presented.

Early stages of oxidation of metallic iron in carbon dioxide

AbstractThe early stages of the oxidation of iron metal in carbon dioxide at atmospheric pressure and 773 K have been studied by use of Auger electron spectroscopy. Initially an oxide film is produced which consists of Fe3O4 with non-stoichiometric excess amounts of oxygen at the surface. It would appear that a layer of Fe2O3 is formed after ∼ 1000 min, but Fe3O4 may merely become enriched in oxygen at the expense of sulphur in order to maintain the anion balance in the lattice. Whether or not a change in oxide occurs the change in sulphur and oxygen concentration is produced either by the separation of the oxide and metal at the oxide/metal interface or by the exhaustive diffusion and oxidation of the sulphur from the bulk metal. Sulphur at the surface of the oxide may playa role in ‘fixing’ carbon produced by the decomposition of carbon dioxide.

Decomposition of Carbon Dioxide in an Induction-Coupled Argon Plasma Jet

Decomposition of Carbon Dioxide in an Induction-Coupled Argon Plasma Jet

THE γ-RAY-INDUCED OXIDATION OF TOLUENE IN LIQUID CARBON DIOXIDE

Abstract The γ-radiolysis of the liquid-phase mixture of toluene and carbon dioxide has been studied at 0°C. The G-value of cresols accounted for 50% of the G-value of the decomposition of carbon dioxide. Speculation was offered on the precursor of cresols.

Kinetics of the Oxidation of Carbon Monoxide and the Decomposition of Carbon Dioxide in a Radiofrequency Electric Discharge. II. Theoretical Interpretation

Kinetics of the Oxidation of Carbon Monoxide and the Decomposition of Carbon Dioxide in a Radiofrequency Electric Discharge. II. Theoretical Interpretation

Kinetics of the Oxidation of Carbon Monoxide and the Decomposition of Carbon Dioxide in a Radiofrequency Electric Discharge. I. Experimental Results

Kinetics of the Oxidation of Carbon Monoxide and the Decomposition of Carbon Dioxide in a Radiofrequency Electric Discharge. I. Experimental Results

The effect of chemisorbed species upon the physical adsorption of argon on nickel oxide

At room temperature, high surface area nickel oxide, prepared by decomposition of nickel hydroxide, chemisorbs oxygen, carbon monoxide, and carbon dioxide. The surface coverage by these species does not exceed 20%. The chemisorption of these gases reduces the physical adsorption of argon by an amount approximately proportional to the coverage by the chemisorbed species. The application of the t-plot shows that the nickel oxide is a microporous material and that the blocking of the micropores by chemisorbed species is responsible for the decrease in the physical adsorption of argon. Considerations on the correct application of the t-plot are developed.

Photosynthetic carbon metabolism.

Early in this century, it was thought that photochemical decomposition of carbon dioxide gave oxygen and reduced carbon (1). In 1931, van Niel (2) formulated photosynthesis as a transfer of hydrogen from water to carbon dioxide inn higher plants, and from other hydrogen donors to carbondioxide in photosynthetic bacteria. The photochemical decomposition of water to give oxygenl received further support when Hill and Scarisbrick (3) found that illuminated chloroplasts evolve oxygen when supplied with a suitable electronm acceptor. Then, in 1941, Ruben and coworkers (4) showed that oxygen evolved during photosynthesis agreed in isotopic composition with the oxygen of water rather than with that of carbon dioxide. With the discovery of radiocarbon, Rubenand coworkers (5, 6) could prove that the fixation of carbon dioxide proceeds in the dark to an intermediate compound, which is subsequently transformed in the light.

Wall effects in the electrical discharge decomposition of carbon dioxide at low pressures

Wall effects in the electrical discharge decomposition of carbon dioxide at low pressures