Poisoning of SCR Catalysts used in Municipal Waste Incineration Applications

Jan G. M. Brandin,C. U. Ingemar Odenbrand

doi:10.1007/s11244-017-0816-y

Abstract

A commercial vanadia, tungsta on titania SCR catalyst was poisoned in a side stream in a waste incineration plant. The effect of especially alkali metal poisoning was observed resulting in a decreased activity at long times of exposure. The deactivation after 2311 h was 36% while the decrease in surface area was only 7.6%. Thus the major cause for deactivation was a chemical blocking of acidic sites by alkali metals. The activation–deactivation model showed excellent agreement with experimental data. The model suggests that the original adsorption sites, from the preparation of the catalyst, are rapidly deactivated but are replaced by a new population of adsorption sites due to activation of the catalyst surface by sulphur compounds (SO2, SO3) in the flue gas.

Highlights

The Selective Catalytic Reduction (SCR) technique, for reduction of N Ox with ammonia, was originally invented in the early 60s, developed in Japan in the 70s and introduced in Europe in the 80s
Due to the concern about greenhouse gases, the use of renewable fuel has increased, in order to reduce the use of fossil fuel
This decrease is especially noted in the micro pore surface area, which decreases from 1.99 to 0.29 m2/g from 150 to 450 °C

Summary

Introduction

The Selective Catalytic Reduction (SCR) technique, for reduction of N Ox with ammonia, was originally invented in the early 60s, developed in Japan in the 70s and introduced in Europe in the 80s. While the previous use of fossil gas, diesel or oil produced a rather particulate free flue gas, the new fuels contain larger amounts of alkali metals. They generate a large portion of fly ash. The catalyst should be placed after the boiler in a high dust position. Among them alkali metals are of a major concern [2,3,4,5] They cause deactivation of the catalysts, by blocking the Brønsted acid sites, in the same way as for applications burning forest residues [2, 6]

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