Novel Amine Modified Nanoporous SBA-15 Sorbent for the Removal of H2S from Gas Streams in the Presence of CH4

A new sorbent has been developed by grafting Hexamethylenetetramine on a mesoporous molecular sieve (SBA-15) by wet impregnation method. This sorbent (Hexamine/SBA-15) has been characterized using N-2 physisorption, X-ray diffraction (XRD) at low angles (2 theta degrees) and FT-IR. To investigate the H2S removal capacity of this adsorbent from 9000 ppm H2S balance CH4-containing gas mixtures, the breakthrough tests have been performed on a fixed-bed flow system. SBA-15 without amine loading showed a very low H2S adsorption capacity (0.015 mmol-Sulfur/g-sorbent) and saturation capacity (0.032 mmol-Sulfur/g-sorbent). The results show that after the amine loading, hexamine is dispersed inside the mesochannels of mesoporous SBA-15. Effects of the amine loading and sorption temperature on the sorption behavior of this developed sorbent have also been studied. Increase of amine loading enhances the H2S sorption on this sorbent, When Hexamine was 50wt%, the removal performance was optimum(q(b)=0.9 mmol/g-sorbent). With increase in temperature, both the breakthrough capacity (q(b)) and the saturation capacity (q(s)) decrease. High sorption capacity is observed at low temperature (T=22 degrees C, q(s)=1.9 mmol/g-sorbent) which provides a promoting effect in removal of H2S from gas mixtures streams on the developed Hexamine/SBA-15 sorbent. This developed sorbent is regenerated easily at 100 degrees C, and shows very good stability. The breakthrough capacity decreased from 0.9 mmol. g(-1) for the first cycle to 0.75 mmol g(-1) for the second cycle and 0.74 mmol g(-1) for the third cycle. Although the breakthrough capacity decreased about 83 % of the first breakthrough tim, H2S can be recovered.