Selective removal of hydrogen sulfide from simulated biogas streams using sterically hindered amine adsorbents

Three silica supported sterically hindered amines, two moderately hindered amines (containing primary and secondary amine groups) and one severely hindered amine (containing a secondary amine group), are evaluated for removal of H2S from mixed CH4/CO2/H2S streams akin to those found in natural gas deposits or in biogas streams. The results from in-situ infrared spectroscopy and both calculated and simulated heats of adsorption suggest a hydrogen bonding sorption mechanism for H2S, involving two amine molecules on all sterically hindered amine (SHA) adsorbents. Basicity calculations with a sterically hindered Lewis acid suggest that steric hindrance is responsible for the limited amine-CO2 interactions on the hindered amines, but has less effect on the amine-H2S interactions. Using a multicomponent gas mixture of H2S/CO2/CH4, a range of experiments confirm that moderately sterically hindered amines can simultaneously remove CO2 and H2S while the most severely sterically hindered amine, based on a tert-butylaminopropylsilyl-grafted species, is the best adsorbent for the selective removal of H2S in the presence of low and high CO2 concentrations, offering facile regeneration. The H2S selectivity achieved, with essentially no measurable CO2 uptake, is the highest H2S selectivity reported to date amongst similar gas mixtures for solid sorbents.

Jaar van publicatie:2020

Toegankelijkheid:Closed