Experimental investigation of the effect of poly-N-vinyl pyrrolidone (PVP) on methane/propane clathrates using a new contact mode

10.1016/j.ces.2013.02.011Chemical Engineering Science93387-394CESC

The impact of SO2 on post combustion carbon dioxide capture in bed of silica sand through hydrate formation

Hydrate crystallization technology is one of the novel approaches for capturing carbon dioxide from flue gases. The presence of impurities such as SO2, NO2, H2S can influence the CO2 hydrate formation process. In the present work the impact of SO2 on hydrate equilibrium was investigated using the isothermal pressure search method. The hydrate equilibrium shifted to low pressures and high temperatures in the presence of small amount SO2. For example the hydrate formation pressure shifted from 7.7MPa to 7.25MPa at 273.75K. In addition, the presence of SO2 enhanced the initial hydrate formation rate and final moles of gas consumed 16h after the hydrate nucleation. The CO2 and SO2 gases were preferentially incorporated into the hydrate phase. The presence of SO2 helps the thermodynamics and kinetics of the hydrate formation process. Therefore complete removal of this SO2 impurity is not necessary; in fact it aids both thermodynamically and kinetically for hydrate formation, which indeed is a positive factor for the capture and geological sequestration of CO2 in the form of hydrates. The addition of THF reduces the CO2/N2/SO2 hydrate formation conditions (from 7.25MPa to 0.15MPa at 273.75K), which is practically important for reducing high compression costs. Moreover, the presence of THF decreases the hydrate nucleation time but reduces the hydrate formation rate significantly. \ua9 2013.Peer reviewed: YesNRC publication: Ye

Enhanced rate of gas hydrate formation in a fixed bed column filled with sand compared to a stirred vessel

10.1016/j.ces.2011.10.030Chemical Engineering Science681617-623CESC

Assessing the performance of commercial and biological gas hydrate inhibitors using nuclear magnetic resonance microscopy and a stirred autoclave

The formation kinetics of methane/ethane/propane hydrate in the presence of kinetic inhibitors was investigated using 1H nuclear magnetic resonance imaging (MRI) as well as a more-traditional method using a stirred autoclave. These studies were facilitated by fabricating a multi-drop insert for 1H NMR micro-imaging, which allowed the comparison of the performance of microliter quantities of several inhibitors simultaneously and under the same conditions. Both methods showed that hydrate nucleation and growth were delayed significantly in the presence of inhibitors, which included two biological inhibitors (antifreeze proteins) and a commercial inhibitor. The results demonstrate that MRI is a useful tool for the visualization and evaluation of the performance of kinetic inhibitors on mixed gas hydrate formation. The MRI technique should prove especially valuable in the case of analysis of potential inhibitors, pre-commercialization, which are available in only limited quantities, such as biological inhibitors. This technique may also find utility in the exploration of differences in inhibitor performance, which may suggest distinct mechanisms of inhibitor action.Peer reviewed: YesNRC publication: Ye

Inhibition of Gas Hydrate Nucleation and Growth: Efficacy of an Antifreeze Protein from the Longhorn BeetleRhagium mordax

Antifreeze proteins (AFPs) are characterized by their ability to protect organisms from subfreezing temperatures by preventing tiny ice crystals in solution from growing as the solution is cooled below its freezing temperature. This inhibition of ice growth is called antifreeze activity, and in particular, certain insect AFPs show very high antifreeze activity. Recent studies have shown AFPs to be promising candidates as green and environmentally benign inhibitors for gas hydrate formation. Here we show that an insect antifreeze protein from the longhorn beetle, Rhagium mordax (RmAFP1), the most potent protein yet found for freezing inhibition, can inhibit methane hydrates as effectively as the synthetic polymeric inhibitor polyvinylpyrrolidone (PVP). In high pressure rocking cell experiments, onset hydrate nucleation temperatures and growth profiles showed repeatable results. RmAFP1 clearly showed inhibition of hydrates compared to amino acids (l-valine and l-threonine) and the protein bovine serum albumin (BSA). This indicates that proteins or amino acids do not generally inhibit hydrate formation. The promising performance of RmAFP1 as a new green kinetic hydrate inhibitor could further the development and increased production of green hydrate inhibitors