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

• Published in: Journal of catalysis 2004-10, Vol.227 (1), p.117-129
• Main Authors: Barth, Jan-Olaf, Jentys, Andreas, Iliopoulou, Eleni F., Vasalos, Iacovos A., Lercher, Johannes A.
• Format: Article
• Language: English
• Subjects: Catalysis; Chemistry; Exact sciences and technology; Fluid catalytic cracking (FCC); General and physical chemistry; Ion-exchange; NO x reduction; Oxidative regeneration; Pillared zeolites; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Zeolites: preparations and properties
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2004.06.021

MCM-36 materials containing mixed oxide pillars (MgO Al 2O 3-MCM-36, BaO Al 2O 3-MCM-36, MgO Al 2O 3 SiO 2-MCM-36, BaO Al 2O 3 SiO 2-MCM-36) were investigated as additives for the in situ reduction of NO x 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 ( ∼ 85 % ) and high N 2 yields ( ∼ 80 % ) 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 (MgO Al 2O 3-MCM-36: 77% N 2 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 ( ∼ 30 % NO reduction). It is speculated that Brønsted acid sites in the zeolite layers of the composite materials catalyze the reduction of NO with NH 3, which is an intermediate in the regeneration of nitrogen-containing carbonaceous deposits on deactivated FCC catalysts.