Carbon formation and active site of alumina supported platinum catalyst in steam methane reforming containing sulfur

The effect of sulfur poisoning on Pt/α-Al₂O₃ catalysts in steam methane reforming (SMR) was studied using dimethyl sulfide (DMS). SMR with and without 10 ppm DMS addition was carried out over 0.1-2.0 wt.% Pt//α-Al₂O₃ catalysts. Catalyst deterioration occurred at an early stage, but not inactivation in the presence of DMS. Additionally, after the supply of DMS was stopped, the activity was completely restored. DMS in the reaction gas also caused severe sintering of the Pt particles and promoted carbon formation on the 1.0-2.0 wt.% Pt catalysts. Meanwhile, carbon formation did not occur on the 0.1 wt.% Pt catalysts. The Pt sintering and carbon formation characteristic were independent of the SMR activity. These results suggest that three different active sites were formed on the Pt//α-Al₂O₃. First is a SMR active site not affected by DMS. The second is an active site that loses activity due to DMS, but completely regenerated after the supply of DMS was stopped. The third is not an active site of SMR but where sintered Pt accelerated CH₄ decomposition to produce carbon.