Novel derivatives of MCM-36 as catalysts for the reduction of nitrogen oxides from FCC regenerator flue gas streams

MCM-36 materials containing mixed oxide pillars (MgOsingle bondAl2O3-MCM-36, BaOsingle bondAl2O3-MCM-36, MgOsingle bondAl2O3single bondSiO2-MCM-36, BaOsingle bondAl2O3single bondSiO2-MCM-36) were investigated as additives for the in situ reduction of NOx formed during the regeneration of coked cracking catalysts in FCC units. The additives were investigated under reaction conditions similar to the oxygen-depleted and the oxygen-enriched zone of the FCC regenerator. MCM-36-type materials with basic mixed oxide clusters in the interlayer galleries showed high NO conversions (image) and high N2 yields (image) under oxygen-deficient reaction conditions. The catalytic activity of MCM-36 with alkaline earth metal aluminum oxide pillars incorporated between the zeolitic layers was higher (MgOsingle bondAl2O3-MCM-36: 77% N2 yield at 650 °C) compared to the nonpillared parent material MCM-22 (22%). The materials have been added in regeneration experiments to industrial (coked) FCC catalysts in a fluidized-bed reactor. The materials led to a reduction of NO emissions also in the presence of Pt-based CO combustion promoters (image NO reduction). It is speculated that Brønsted acid sites in the zeolite layers of the composite materials catalyze the reduction of NO with NH3, which is an intermediate in the regeneration of nitrogen-containing carbonaceous deposits on deactivated FCC catalysts.