scholarly journals Advances in the Radiocarbon Analysis of Carbon dioxide at the NERC Radiocarbon Facility (East Kilbride) using Molecular sieve Cartridges

Radiocarbon ◽  
2019 ◽  
Vol 61 (6) ◽  
pp. 1855-1865
Author(s):  
M H Garnett ◽  
Josephine-Anne Newton ◽  
P L Ascough
Keyword(s):  
Carbon Dioxide ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Content Standards ◽  
Sieve Methods ◽  
Scientific Investigations ◽  
Consensus Values ◽  
Anthropogenic Processes ◽  
Automated Procedures ◽  
Quality Assurance Standards

ABSTRACTRadiocarbon (14C) analysis of carbon dioxide (CO2) provides unique information on the age, turnover and source of this important greenhouse gas, raising the prospect of novel scientific investigations into a range of natural and anthropogenic processes. To achieve these measurements, cartridges containing zeolite molecular sieves are a reliable and convenient method for collecting CO2 samples. At the NERC Radiocarbon Facility (East Kilbride) we have been refining our molecular sieve methods for over twenty years to achieve high-quality, reproducible and precise measurements. At the same time, we have been developing novel field sampling methods to expand the possibilities in collecting gas from the atmosphere, soil respiration and aquatic environments. Here, we present our latest improvements to cartridge design and procedures. We provide the results of tests used to verify the methods using known 14C content standards, demonstrating reliability for sample volumes of 3 mL CO2 (STP; 1.6 mg C) collected in cartridges that had been prepared at least three months earlier. We also report the results of quality assurance standards processed over the last two years, with results for 22 out of 23 international 14C standards being within measurement uncertainty of consensus values. We describe our latest automated procedures for the preparation of cartridges prior to use.

scholarly journals Particulate and membrane molecular sieves prepared to adsorb carbon dioxide in packed and staggered adsorber

2018 ◽  
Vol 24 (4) ◽  
pp. 345-356
Author(s):  
Honda Wu
Keyword(s):  
Carbon Dioxide ◽  
Adsorption Isotherms ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Gas Flow ◽  
Fixed Bed ◽  
Adsorption System ◽  
Gas Flow Rate ◽  
Hydrothermal Temperature ◽  
Fixed Bed Adsorption

A fixed-bed adsorption system was used to remove carbon dioxide in this study. Adsorption isotherms were obtained from a microbalance system and the characteristics of a molecular sieve affected by preparing variables were analyzed. The adsorbents, including a particulate molecular sieve and a molecular sieve membrane, were used to adsorb carbon dioxide in the fixed-bed adsorption system. Since the surface properties of the molecular sieve were affected by the preparation variables, particulate and membrane molecular sieves were synthesized to examine the effects of preparation variables on the adsorption of carbon dioxide. The experimental results showed that the pore size of the molecular sieve has increased with the chain length of quaternary ammonium salts and higher hydrothermal temperature. Adsorption isotherms for carbon dioxide adsorbed by particulate molecular sieve and molecular sieve membrane were favourable. In addition, the breakthrough curve for the lower inlet gas flow rate was closer to that of the particulate molecular sieve under the same amount of outlet fresh air. The results demonstrated that the adsorption system for the staggered alumina carriers coated with molecular sieve membranes is worthy of development.

Preparation and Characterization of Ni-Containing Aluminophosphate Molecular Sieves

2011 ◽  
Vol 418-420 ◽  
pp. 617-620
Author(s):  
Ying Sun ◽  
Lan Ying Ge
Keyword(s):  
Oxidation State ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Crystalline Form ◽  
Spectroscopic Techniques ◽  
Tetrahedral Coordination ◽  
Tetrahedral Geometry ◽  
Nickel Ions ◽  
Aluminophosphate Molecular Sieves

Aluminophosphate molecular sieve and Ni(II)-containing APO-5 materials were synthesized hydrothermally and characterized by various analytical and spectroscopic techniques. It indicates that the nickel ions with a divalent oxidation state can incorporate into the tetrahedral coordination in mesoporous aluminophosphate very well. The better crystallizing temperature is explored. A stronger crystalline form is obtained with the addition of HF. Further, microporous aluminophosphate molecular sieves and Ni(II) ions remain in a tetrahedral geometry even after calcination at 550 °C.

Progress in Synthesis of Micro- and Mesoporous Composite Molecular Sieve

2011 ◽  
Vol 396-398 ◽  
pp. 1151-1156
Author(s):  
Wen Yuan Wu ◽  
Chun Wei Shi ◽  
Xue Bian
Keyword(s):  
Hydrothermal Synthesis ◽  
Microwave Radiation ◽  
Vapor Phase ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Vapor Phase Transport ◽  
Mesoporous Composite ◽  
Composite Molecular Sieve ◽  
Potential Applications ◽  
Phase Transport

Micro- and mesoporous composite molecular sieves enable to achieve grades distribution of pore sizes and appropriate collocation of acidity,which have potential applications in catalysis and adsorption of large molecules.This review focus on some of the most recent results during the last decades.The techniques applied to synthesize different micro-mesoporous composite molecular sieves includes single template, dual template, crystallization of mesoporous walls, alkaline desilication, vapor-phase transport synthesis,and microwave radiation hydrothermal synthesis.

scholarly journals Carbon Dioxide Decomposition Over AlPO4 Based Molecular Sieves

2019 ◽  
Vol 8 (1) ◽  
pp. 25-33
Author(s):  
S. Siva Sankari S. Siva Sankari ◽  
M. A. Mary Thangam M. A. Mary Thangam ◽  
Chellapandian Kannan Chellapandian Kannan
Keyword(s):  
Carbon Dioxide ◽  
Molecular Sieves

Characterization of Carbon Molecular Sieves Using Methane and Carbon Dioxide as Adsorptive Probes

Langmuir ◽  
2003 ◽  
Vol 19 (20) ◽  
pp. 8335-8342 ◽  
Author(s):  
S. W. Rutherford ◽  
C. Nguyen ◽  
J. E. Coons ◽  
D. D. Do
Keyword(s):  
Carbon Dioxide ◽  
Molecular Sieves ◽  
Carbon Molecular Sieves

Gas-Solid Chromatographic Determination of Oxygen, Nitrogen, Carbon Dioxide, Ethylene, and Nitrous Oxide at Ambient Temperature

1973 ◽  
Vol 56 (1) ◽  
pp. 119-123
Author(s):  
Martin J Finkelson
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Ambient Temperature ◽  
Molecular Sieve ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Digital Integrator ◽  
In Series ◽  
Peak Areas

Abstract A gas-solid chromatographic method is described for the separation and determination of 5 medicinal gases at ambient temperature, using 2 gas chromatographic columns, Porapak Q and Molecular Sieve 13X, operated in series with a 6-port thermal conductivity detector and I recorder. An electronic digital integrator is used for calculating peak areas. Data on retention time, linearity, reproducibility of injection, and comparison with absorption methods are presented. Analytical results for oxygen, nitrogen, carbon dioxide, ethylene, and nitrous oxide are attainable within 1.0% without the use of an internal standard.

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