Role of Presulfidation and H₂S Cofeeding on Carbon Formation on SS304 Alloy during the Ethane-Steam Cracking Process at 700 °c

The influence of presulfidation and H₂S cofeeding on the carbon formation on SS304 alloy in the ethane-steam cracker was investigated in a laboratory-scale quartz reactor setup. SS304H coupons and SS304L powder samples were exposed to ethane-steam and dry ethane in varying H₂S content (0-50 ppm), and the SS304 samples were characterized by scanning electron microscopy. This study shows that H₂S cofeeding decreases catalytic carbon formation; while it increases the pyrolytic carbon formation during ethane-steam cracking. Preoxidation, presulfidation, and addition of steam to ethane feed also reduces the amount of catalytic carbon formed on the SS304H surface in short-term experiments (4 h). Presulfidation and addition of H₂S to ethane feed significantly influences the shape and size of the carbon formed on the surfaces of investigated metal alloys. Presulfidation and H₂S cofeeding reduced spalling of the SS304H coupon surface during coking/decoking and thermal cycling.