Promoting effect of Pt on Cozeolites upon the SCR of NO{sub x}

Journal Article · Thu Oct 01 04:00:00 EDT 1998 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1998.2210· OSTI ID:672466

Gutierrez, L; Boix, A; Petunchi, J O ^[1]

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1. UNL-CONICET, Santa Fe (Argentina). Inst. de Investigaciones en Catalisis y Petroquimica

The promoting effect of Pt incorporated to Cozeolites (viz., mordenite, ferrierite, ZSM-5, and Y-zeolites) on the selective catalytic reduction (SCR) of NO{sub x} with CH{sub 4} was studied. The PtCo bimetallic zeolites showed higher NO to N{sub 2} conversion and selectivity than the monometallic ones under all reaction conditions tested. The Y-zeolite based samples which were inactive both in the mono and bimetallic samples constituted an exception. The promoting effect was a function of the zeolite type and, for a given zeolite, of the pretreatment of the catalysts and Pt loading. The best results were obtained for a 0.5% Pt loading after reduction of the samples in H{sub 2} flow for 1 h at 350 C. The incorporation of Pt also shows a positive effect in the stability of the samples under wet reaction conditions. The XPS results revealed that in the calcined samples most of the Co{sup 2+} and Pt{sup 2+} was located at exchange positions. After reduction no changes in the binding energies (B.E.) were observed in samples with low Pt loading. For higher contents (viz., 1 to 5 wt%) the B.E. characteristics of Co{degree} and Pt{degree}, as well as Co{sup 2+} an Pt{sup 2+}, were detected. The incorporation of Pt also promoted the Co reducibility in the zeolitic matrix. The greater reducibility and a shift of the maxima in the temperature-programmed reduction profiles suggest a Pt-Co interaction inside of the zeolitic channels. The solid that the reacting mixture initially sees has Co{degree} and Pt{degree} metallic particles highly dispersed in the zeolitic matrix, together with Co{sup 2+}. Some Pt{sup 2+} and protons generated during reduction also appeared. Such species remained after reaction but some reorganization occurred.

• OSTI ID: 672466
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 179; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AIR POLLUTION CONTROL
CATALYTIC EFFECTS
COBALT
NITROGEN OXIDES
PLATINUM
PROMOTERS
SELECTIVE CATALYTIC REDUCTION
ZEOLITES