Strong Enhancement of deSoot Activity of Transition Metal Oxides by Alkali Doping: Additive Effects of Potassium and Nitric Oxide

Piotr Legutko,Wojciech Kaspera,Zbigniew Sojka,Tomasz Jakubek,Paweł Stelmachowski,Andrzej Kotarba

doi:10.1007/s11244-016-0727-3

Abstract

A series of potassium-promoted spinels (Mn, Fe, Co) were prepared with various K+ promoter locations: on the surface (surface promotion) or in the bulk (formation of new layered and tunneled nanostructures via solid state reaction). All prepared samples were characterized by means of X-ray diffraction, Raman spectroscopy, X-ray fluorescence and N2-BET specific surface area analysis. Catalytic activity in soot combustion in different reaction conditions was investigated (tight contact, loose contact, loose contact with NO addition). It was shown that in all cases the nanostructuration is more effective than the surface promotion, with the layered structures of KCo4O8, KMn4O8 being the most catalytically active phases, lowering the soot combustion down to 250 °C. The difference in activity between tight and loose contacts can be bridged in the presence of NO due to its transformation into NO2, which acts as the oxygen carrier from the catalyst surface into soot particles, eliminating the soot-catalyst contact difference.

Highlights

IntroductionThe most important anthropogenic sources are coal combustion in electric plants and home heating systems, waste incineration, and car emissions—soot from fuel combustion and dust from tires wear
During pyrolysis and the incomplete combustion of fuels agglomerated soot particles of different carbonThe most important anthropogenic sources are coal combustion in electric plants and home heating systems, waste incineration, and car emissions—soot from fuel combustion and dust from tires wear
The difference in activity between tight and loose contacts can be bridged in the presence of NO due to its transformation into NO2, which acts as the oxygen carrier from the catalyst surface into soot particles, eliminating the soot-catalyst contact difference

Summary

Introduction

The most important anthropogenic sources are coal combustion in electric plants and home heating systems, waste incineration, and car emissions—soot from fuel combustion and dust from tires wear. Many governments have introduced strict norms for pollutant emission [2]. These have led to the development of new technologies for soot emission reduction. It seems that catalytic diesel particulate filters (CDPF) are the most promising technology. DPFs can lower soot emission by up to 99 % but soot accumulates inside them and regeneration is needed. Catalysts can regenerate DPFs in the temperature of exhaust gasses while a temperature of up to 600 °C is needed for regeneration without any catalyst [3, 4]

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