Abstract
Regeneration and deactivation behaviors of Co-Zn/H-Beta catalysts were investigated in NOx reduction with C3H8. Co-Zn/H-Beta exhibited a good water resistance in the presence of 10 vol.% H2O. However, there was a significant drop off in N2 yield in the presence of SO2. The formation of surface sulfate and coke decreased the surface area, blocked the pore structure, and reduced the availability of active sites of Co-Zn/H-Beta during the reaction of NO reduction by C3H8. The activity of catalyst regenerated by air oxidation followed by H2 reduction was higher than that of catalyst regenerated by H2 reduction followed by air oxidation. Among the catalysts regenerated by air oxidation followed by H2 reduction with different regeneration temperatures, the optimal regeneration temperature was 550 °C. The textural properties of poisoned catalysts could be restored to the levels of fresh catalysts by the optimized regeneration process. The regeneration process of air oxidation followed by H2 reduction could recover the active sites of cobalt and zinc species from sulfate species, as well as eliminate coke deposition on poisoned catalysts. The regeneration pathway of air oxidation followed by H2 reduction is summarized as initial removal of coke by air oxidation and final reduction of the sulfate species by H2.
Highlights
Selective catalytic reduction of NOx by hydrocarbons (HC-SCR) was considered a promising technology for NOx removal [1]
°C) displayed higher activity than Co‐Zn/H‐Beta‐R (H2 + O2, 450 °C). This suggests that combined regeneration is better than single regeneration, and air oxidation followed by H2 reduction is an optimal regeneration is better than single regeneration, and air oxidation followed by H2 reduction is an regeneration sequence for the deactivated Co-Zn/H-Beta catalyst in C3 H8 -SCR
2 reduction showed more 2 reduction catalysts [28], the in situ regeneration process of air oxidation followed by H2 reduction showed more operation and higher regeneration respectively
Summary
Selective catalytic reduction of NOx by hydrocarbons (HC-SCR) was considered a promising technology for NOx removal [1]. In the case of catalysts deactivated by coke deposition, air calcination was considered as an efficient regeneration method [21,22,23,24,25]. No reports focused on the regeneration of HC-SCR catalysts deactivated by dual deactivated by dual impacts of SO2 and coke deposition. Co-Zn/H-Beta was chosen as a deNOx catalyst for C3 H8 -SCR, because it showed good catalytic activity [26]. The regeneration of Co‐Zn/H‐Beta catalysts deactivated by SO2 showed good catalytic activity [26]. The regeneration of Co-Zn/H-Beta catalysts deactivated by SO2 and coke deposition was performed in a combined in situ process of air oxidation and H2 reduction. Coke deposition was performed in a combined in situ process of air oxidation and H2 reduction.
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