The hydrate-based separation of hydrogen and ethylene from fluid catalytic cracking dry gas in presence of n-octyl-β-d-glucopyranoside

Hydrate-based gas separation (HBGS) needs a kinetic promoter to increase its economic value. The kinetic promoters for HBGS should have low foaming ability, high performance on increasing the conversion rate of the water into hydrate (RWH) and little thermodynamic inhibition on hydrate formation. However, no reported kinetic promoter meets all above requirements at same time. According to the experimental results in this work, n-octyl-β-d-glucopyranoside (OGP) met all those requirements of HBGS. For that reason, OGP was proposed as a new kinetic promoter for HBGS, and its effects on HBGS were revealed by investigating the HBGS of hydrogen and ethylene from fluid catalytic cracking dry gas in presence of OGP in this work. OGP enhanced the HBGS performance by increasing RWH from less than 64% to higher than 84%. By one-step separation, the hydrogen concentration was increased from 26.0 mol% to about 46.8 mol% while the ethylene concentration was increased from 52.0 mol% to about 74.4 mol%. The effect of the initial OGP concentration in liquid phase (wp,0) on HBGS increased with the increase in RWH, and the optimum wp,0 was 0.20 mass%. The processing capacity of the OGP solution in the HBGS was about 350 NL feed gas/L. OGP enhanced the promotion of increasing pressure on the HBGS performance. A new model was proposed to predict the thermodynamic equilibrium hydrate formation pressures of the experimental systems: the maximum relative deviation is 5.08% and the average relative deviation is 2.61%.