Splitting Water and Carbon Dioxide via the Heterogeneous Oxidation of Zinc Vapor: Thermodynamic Considerations

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Luke J. Venstrom ◽  
Jane H. Davidson
Keyword(s):  
Carbon Dioxide ◽  
Reaction Times ◽  
Zinc Vapor ◽  
Complete Conversion ◽  
Heterogeneous Oxidation ◽  
Aerosol Reactors ◽  
Carbon Dioxide Splitting ◽  
Heat Recuperation ◽  
Cycle Efficiency ◽  
Splitting Water

The heterogeneous oxidation of zinc vapor is proposed as a promising reaction path for the exothermic step in the two-step Zn/ZnO solar thermochemical water and carbon dioxide splitting cycles. This approach circumvents mass transfer limitations encountered in the oxidation of solid or liquid zinc, promising rapid hydrogen and carbon monoxide production rates concurrent with a complete conversion of zinc to zinc oxide. In this paper, a parametric thermodynamic analysis is presented to quantify the benefit of achieving a rapid and complete conversion of zinc via the heterogeneous oxidation of zinc vapor. The conversion of zinc in polydisperse aerosol reactors has been limited to 20% for reaction times on the order of a minute, resulting in a cycle efficiency of ∼6%. The benefit of completely converting zinc via the heterogeneous oxidation of zinc vapor is an increase in efficiency to 27% and 31% for water and carbon dioxide splitting, respectively. The cycle efficiency could be higher if heat recuperation is implemented.

Splitting Water and Carbon Dioxide via the Heterogeneous Oxidation of Zinc Vapor: Thermodynamic Considerations

2010 ◽  
Author(s):  
Luke J. Venstrom ◽  
Jane H. Davidson
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Carbon Monoxide ◽  
Reaction Path ◽  
Zinc Vapor ◽  
Complete Conversion ◽  
Heterogeneous Oxidation ◽  
Carbon Dioxide Splitting ◽  
Heat Recuperation ◽  
Splitting Water

The heterogeneous hydrolysis/oxidation of zinc vapor is proposed as a promising reaction path for the exothermic step in two-step Zn/ZnO solar thermochemical water and carbon dioxide splitting cycles. This approach circumvents mass transfer limitations encountered in the oxidation of solid or liquid zinc, promising rapid hydrogen/carbon monoxide production rates and complete conversion of zinc. In this paper, a parametric thermodynamic analysis is presented to quantify the penalty of generating zinc vapor as well as the benefit of achieving complete conversion of zinc via the heterogeneous oxidation of zinc vapor. The penalty for generating zinc vapor is a reduction in water splitting efficiency from 36% to 27% and a reduction in carbon dioxide splitting efficiency from 39% to 31%. However, with heat recuperation this penalty can be avoided. The benefit of completely converting zinc via the heterogeneous oxidation of zinc vapor is an increase in efficiency from ∼6% to 27% and 31% for water and carbon dioxide splitting, respectively.

Heterogeneous oxidation of zinc vapor by steam and mixtures of steam and carbon dioxide

2018 ◽  
Vol 183 ◽  
pp. 223-230 ◽  
Author(s):  
Luke J. Venstrom ◽  
Paul Hilsen ◽  
Jane H. Davidson
Keyword(s):  
Carbon Dioxide ◽  
Zinc Vapor ◽  
Heterogeneous Oxidation

Demonstration of a Solar Reactor for Carbon Dioxide Splitting via the Isothermal Ceria Redox Cycle and Practical Implications

2016 ◽  
Vol 30 (8) ◽  
pp. 6654-6661 ◽  
Author(s):  
Brandon J. Hathaway ◽  
Rohini Bala Chandran ◽  
Adam C. Gladen ◽  
Thomas R. Chase ◽  
Jane H. Davidson
Keyword(s):  
Carbon Dioxide ◽  
Redox Cycle ◽  
Solar Reactor ◽  
Carbon Dioxide Splitting ◽  
Practical Implications

Reduction enthalpy and charge distribution of substituted ferrites and doped ceria for thermochemical water and carbon dioxide splitting with DFT+U

2016 ◽  
Vol 18 (34) ◽  
pp. 23587-23595 ◽  
Author(s):  
D. A. Dimitrakis ◽  
N. I. Tsongidis ◽  
A. G. Konstandopoulos
Keyword(s):  
Carbon Dioxide ◽  
Charge Distribution ◽  
Solar Fuels ◽  
Doped Ceria ◽  
Nickel Ions ◽  
Carbon Dioxide Splitting

Effect of Nickel ions on reduction energy and charge distribution of oxygen – neighbouring ions in NiFe2O4 for solar fuels.

Primary Study on Carbon Dioxide Power Cycle of HTGR

2008 ◽  
Author(s):  
Chengjie Duan ◽  
Xiaoyong Yang ◽  
Jie Wang ◽  
Suyuan Yu
Keyword(s):  
Carbon Dioxide ◽  
High Temperature ◽  
Physical Properties ◽  
Critical Pressure ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Pressure Cycle ◽  
Cycle Efficiency ◽  
Thermal Physical Properties

At present, power cycles used in HTGR are indirect steam Rankine cycle and helium Brayton cycle. Using water or helium as working fluid which transform thermal energy into mechanical energy for HTGR power cycle has many disadvantages. Steam cycle could choose steam system which is similar to conventional coal-fired power plant, but because of the limit of material and equipments, there is big temperature difference between the steam and the helium, that makes big loss of thermal power and lowers the cycle efficiency. Helium can reach a high temperature in HTGR Brayton cycle and it has good stability, but because of helium has big isentropic exponent and low density, it is difficult to compress and makes helium turbine has shorter blades and more stages than normal gas turbine. Carbon dioxide has good thermal stability and physical properties. To avoid the reaction of CO2 with graphite and canning of fuel element at high temperature, it should be used in an indirect cycle as second loop working fluid. CO2 has appropriate critical pressure and temperature (7.38MPa, 304.19K) and can choose three types of cycle: supercritical cycle, subcritical-pressure cycle and trans-critical-pressure cycle (CO2 sometimes works under supercritical pressure, some times under subcritical-pressure). Carbon dioxide cycle works in a high pressure, so it makes pressure loss lower. When CO2 works close to its critical point, its density become larger than other conditions, and not change very much, this permits to reduce compress work. The thermal physical properties of carbon dioxide are totally different from helium due to CO2 works as real gas in the cycle. That causes the calculation of CO2 thermal physical properties, heat transfer and power cycle efficiency become difficult and need to be iterated. A systematic comparison between helium and carbon dioxide as working fluid for HTGR has been carried out. An empirical equation had been selected to estimate the thermal physical properties of carbon dioxide. Three types of carbon dioxide power cycle have been analyzed and the thermal efficiency has been calculated. A detailed introduction to the basic calculation process of the CO2 cycle thermal efficiency had been presented in the paper.

THE ANAEROBIC DISSIMILATION OF D-GLUCOSE-1-C14, D-ARABINOSE-1-C14, AND L-ARABINOSE-1-C14 BY AEROBACTER AEROGENES

1954 ◽  
Vol 32 (1) ◽  
pp. 147-153 ◽  
Author(s):  
A. C. Neish ◽  
F. J. Simpson
Keyword(s):  
Carbon Dioxide ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Carboxyl Groups ◽  
Methyl Groups ◽  
Carboxyl Group ◽  
Complete Conversion ◽  
Aerobacter Aerogenes ◽  
Methyl Group ◽  
Ethanol Acetic Acid

D-Glucose-1-C14, D-arabinose-1-C14, and L-arabinose-1-C14 were dissimilated anaerobically by Aerobacter aerogenes. The major products (2,3-butanediol, ethanol, acetic acid, lactic acid, formic acid, and carbon dioxide) were isolated and the location of C14 determined. The products from glucose were all labeled, mainly in the methyl groups, in agreement with the hypothesis that they were derived from methyl-labeled pyruvate formed by the reactions of the classical Embden–Meyerhof scheme for glycolysis. The products from both pentoses appeared to have been formed from pyruvate labeled in both the methyl and carboxyl groups with twice as much C14 in the methyl group as in the carboxyl group. This result may be explained quantitatively by a hypothesis assuming complete conversion of pentose to triose via a heptulose.

scholarly journals Nanopatterning of carbonaceous structures by field-induced carbon dioxide splitting with a force microscope

2010 ◽  
Vol 96 (14) ◽  
pp. 143110 ◽  
Author(s):  
R. Garcia ◽  
N. S. Losilla ◽  
J. Martínez ◽  
R. V. Martinez ◽  
F. J. Palomares ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Splitting
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