Showing papers by "Alan L. Chaffee published in 2014"

Reactions with CO/H2O of Two Marine Algae and Comparison with Reactions under H2 and N2

Abstract: The reactions of a strain of marine alga Chlorococcum sp. and of a polystrain containing a mixture of marine algae with CO/H2O have been studied. The yields and chemical composition of the products...

Quantification of Aqueous Monoethanolamine Concentration by Gas Chromatography for Postcombustion Capture of CO2

Abstract: The availability of reliable analytical methods for measuring amine concentrations is necessary for optimum operation of aqueous amine CO2 separation systems being employed for postcombustion capture (PCC) of CO2. A GC-FID (gas chromatography with flame ionization detection) method is described for the reliable quantification of 30% (w/w) monoethanolamine (MEA) in severely degraded solvent samples. The observation of intermittent splitting of the MEA peak was a major concern with this approach. The use of a wide-bore column led to improved MEA peak resolution and peak shape. The reliability and robustness of the GC-FID method were assessed by analyzing degraded 30% (w/w) MEA solvent samples from CSIRO’s pilot plant at AGL’s Loy Yang power station in Victoria, Australia. The results were compared with those obtained by titration and total organic carbon (TOC) measurements of the same samples. The MEA concentrations obtained by the GC-FID and titration methods were statistically similar. In contrast, the ME...

Multiple sorption cycles evaluation of cadmium oxide–alkali metal halide mixtures for pre-combustion CO2 capture

Abstract: Cadmium oxide–alkali metal halide mixtures for pre-combustion CO2 capture were made using a wet mixing approach. Some of the samples were pelletised in as-synthesised state as well as with SBA-15 silica addition. In a multiple CO2 sorption cycle test via thermogravimetric analysis, the best performing powder material by capacity and kinetics (a cadmium oxide made from carbonate doped with 17.5 wt% sodium iodide) exhibited a sorption capacity loss from 17 to 2 wt% after 25 cycles of partial pressure swing sorption at atmospheric pressure and temperatures of 285 and 305 °C. When the initial decomposition of the carbonate took place in inert gas (Ar or N2 instead of air), the cyclic stability was improved. Water addition (1 vol%) to the sorption gas further improved the cyclic CO2 sorption stability and capacity. Elemental analysis of the samples after cyclic exposure to CO2 revealed that the capacity loss is associated with loss of iodine, whereas the sodium remains. Water addition, however, had no significant effect on this iodine loss. Pellets made from carbonate performed with a working capacity of 10 wt%, but lost their mechanical integrity during multicyclic sorption. If made in the oxide state, pellets remained sturdy, but showed almost no working capacity. The addition of 13.7 wt% SBA-15 improved the working capacity of the oxide pellet to a stable value of 5.2 wt% over 25 cycles. In situ powder X-ray diffraction showed the reversible isothermal phase transformation of CdO to CdCO3 during three cycles of sorption and also revealed the presence of a crystalline sodium iodide phase, which appeared to be lost with increasing number of sorption cycles.

Improvements in the Pre-Combustion Carbon Dioxide Sorption Capacity of a Magnesium Oxide–Cesium Carbonate Sorbent

Abstract: Cesium-carbonate-doped magnesium oxide has been shown to be a prospective candidate for pre-combustion CO2 capture at temperatures between 300 and 410 °C. Materials were synthesized by wet mixing commercially available materials as well as a solvothermal approach using a magnesium methoxide in methanol solution. The materials were activated by heat treatment at 600–610 °C to yield the active CO2 sorbent. The sorbents showed working capacities of around 4 wt % in up to 25 partial pressure swing (12 min of sorption and 24 min of desorption) cycles. If the cesium carbonate was dissolved in the magnesium methoxide solution before solvothermal synthesis, multi-cyclic working capacities were increased to 5 wt %. Brunauer–Emmett–Teller surface area measurements of the activated materials showed that the solvothermal method led to materials with higher surface areas of ∼13 m2/g, as compared to 3.4 m2/g if made from commercial MgO. Transmission electron microscopy showed the morphology of the activated solvotherma...

Formation of a non-porous cobalt-phosphonate framework by small pH change in the preparation of the microporous STA-16(Co)

Abstract: The initial pH in the preparation of STA-16(Co) was found to have a great impact on the assembly of the MOF and the resulting porosity. The formation of a non-porous Co(II)-phosphonate pillared layer-structure was observed after changing the initial pH from 6.2 to 7.2 with distinct differences in the coordination environment of the cobalt centres.

Characterisation of the phase-transformation behaviour of Ce2O(CO3)2·H2O clusters synthesised from Ce(NO3)3·6H2O and urea

Abstract: X-ray diffraction (XRD) was used to determine the temperature at which the transformation of Ce 2 O(CO 3 ) 2 ·H 2 O to ceria (CeO 2 ) occurs under both a flow of nitrogen and air as a function of temperature. The Ce 2 O(CO 3 ) 2 ·H 2 O synthesised from Ce(NO 3 ) 3 ·6H 2 O and urea was further investigated using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD results indicate that, under a flow of nitrogen, CeO 2 is formed at temperatures greater than 500 °C and that this occurs via an as yet unidentified intermediate phase, which is present between 430 and 540 °C. Results obtained by the XRD correspond to those obtained using TGA, which show weight losses commencing at 430 and at 465 °C. No further weight loss occurs above 540 °C, because of the formation of CeO 2 as the stable product. The crystallite size was also determined and observed to increase with increasing temperature. Under a flow of air the transformation occurred at a lower temperature, as CeO 2 was formed at 250 °C. SEM and TEM reveal the particles have a rod-shaped morphology which is retained after calcination. These results may be used to optimise synthesis methods to minimise crystallite size growth and reduce sintering that is undesirable in many applications, particularly catalysis.

Pelletized form of a composite material and method of producing same

Abstract: A process for the preparation of a pelletized form of a composite material for gas separation applications, the composite material including a solid support material and at least one separate sorption active phase, wherein the process includes the following steps: a. treating the composite material with a gas to alter the physical characteristics of the at least one separate sorption active phase and transform the composite material into a different form to facilitate pelletization of the treated composite material; and, b. compressing or compacting the treated composite material to prepare the pelletized form of the composite material.

Pelletized silica and polyethyleneimine composites for CO2 capture via adsorption

Abstract: Polyethyeleneimine (PEI) loaded mesocellular siliceous foam (MCF) composite powders were compressed via a novel process to prepare the sorbents in pelletized form, as preferred for CO2 capture processes, without additional binder. Direct compression of the MCF-PEI composite powders to prepare pelletized sorbent was found to be complicated by product extrusion and tackiness. A novel method to overcome this problem was developed in this work. This resulted in pellets that exhibit similar CO 2 capacities to the analogous powdered sorbents, with only slightly reduced sorption capacities and kinetics. The pellets exhibited up to 9 wt % and 4 wt % CO 2 process adsorption capacity for simulated CO 2 capture from flue gas (~15 % CO2) via temperature swing adsorption (TSA) and pressure swing adsorption (PSA) respectively. Thus, the MCF-PEI pellets prepared by this new approach are of particular interest for application to the post combustion capture (PCC) of CO 2 from flue gas streams.