Enhanced formation kinetics of mixed H2/THF hydrate in the presence of nano promoters

It is anticipated to achieve safe, economical, and high-density hydrogen storage via hydrate, but sluggish formation kinetics of H 2 hydrate and low hydrogen storage capacity limit its application, and appropriate kinetic promoters are required to improve the situation. In this work, three nano promoters were prepared by soap-free emulsion polymerization method, the functional groups of -SO 3 − , –COO − and -N(CH 3 ) 3 + were separately immobilized on nano spheres to produce the nano promoters of -SO 3 − @PSNS, –COO − @PSNS and -N(CH 3 ) 3 + @PSNS, and their influence on the formation kinetics of mixed H 2 /THF hydrate was evaluated, while the performance of conventional kinetic promoters of methane hydrate was also estimated for comparison. It was found that the formation kinetics of mixed H 2 /THF hydrate was enhanced in the presence of nano promoters, which improve early growth of H 2 /THF hydrate and later water-to-hydrate conversion, leading to large hydrogen storage capacity. -SO 3 − @PSNS causes H 2 /THF hydrate to be looser and performs the best among the three nano promoters, hydrogen storage capacity in -SO 3 − @PSNS system is up to 0.467 wt% at 12 MPa, which increase by 39.8% comparing with that in pure THF system, and satisfactory hydrogen storage capacity of 0.303 wt% was also obtained under milder condition (7 MPa). For conventional kinetic promoters, L-methionine performs the best and shows similar promotion effect like -SO 3 − @PSNS, but it is excluded for large-scale industrial application when taking its high cost and perishable nature into consideration, whereas this scenario is improved by the proposed nano promoters.