Kinetics Of Carbon Dioxide Hydrate Formation Promoted By Amino Acids

The research and development of carbon dioxide(CO2)hydrate related technologies will solve problems we face today and in the future,especially,the global warming caused by CO2 emission.Compared with other traditional technologies for CO2 capture and storage(CCS),hydrate-based approach for CCS has the advantages of small equipment investment,simple process,and relatively low cost.However,the kinetics of hydrate formation is sluggish.One of the effective approaches to enhance hydrate formation kinetics is the use of surfactants as kinetic promoters.However,the use of these kinds of promoters will cause a large amount of foam during the decomposition of the hydrate,in addition,such promoters are mainly derived from petrochemical feedstocks.From the perspective of green environmental protection,this study used natural amino acids as promoters for CO2 hydrate formation.The main contents of the study are as follows:(1)By comparing the effects of 20 kinds of natural amino acids on the formation of CO2 hydrate,it was found that methionine,cysteine,isoleucine,and tryptophan could enhance the kinetics of CO2 hydrate formation at a concentration of 0.2 wt%,and their maximum gas storage capacities were 3 56,3 5 1,3 3 4,356 mg/g respectively.For threonine and valine,there were no promotion effect at low concentrations,but the 2 kinds of amino acids can promote the formation of CO2 hydrate at a concentration of 1 wt%,and the maximum storage capacities were 124 and 168 mg/g,respectively.(2)The effect of structure-activity relationship,optical rotation,and symmetry on the formation of CO2 hydrate were systematically studied for the first time,and a new type of CO2 hydrate promoter,5-fluorocytosine,was first reported.Furthermore,the surface activity of the amino acid solution at different concentrations was studied,which would provide basic data for further exploring the promoting mechanism of amino acids on CO2 hydrate formation.(3)For potential industrial application of hydrate-based CCS,the effects of temperature,solubility of amino acids,and inorganic salt on CO2 hydrate formation were studied.In additon,the CO2 storage capacity of hydrate-based approach was compared with dry hydrated potassium carbonate(DHPC)approach and monoethanolamine(MEA) approach.