Insights into hydrothermal aging of phosphorus-poisoned Cu-SSZ-13 for NH3-SCR
Artikel i vetenskaplig tidskrift, 2019

Automotive catalysts are continuously exposed to different poisons and to high temperature, which result in hydrothermal aging. Phosphorus is one of the poisons that the catalyst could be exposed to and it originates from the lubricant oil. In this work, we study the influence of phosphorus poisoning on the catalytic performance and the deactivation mechanism in the hydrothermal aging of Cu-SSZ-13 catalysts. Phosphorus poisoning was performed by impregnating the Cu-SSZ-13 catalysts with (NH4)2HPO4solution using the incipient wetness impregnation method, which allowed us to precisely control the amount of phosphorus poison on the catalyst. XPS results show that phosphorus oxide (P2O5), metaphosphate (PO3–) and phosphate (PO43–) are formed on the surface of phosphorus-poisoned catalysts, and metaphosphate is the main compound among those species. Phosphorus tends to interact with copper sites and strongly impacts the electronic and reduction property of Cu, as disclosed using EDX mapping, UV–vis DRS and H2-TPR. Results of catalytic activities show that phosphorus poisoning is more severe on ammonia and NO oxidation reactions than on standard ammonia-SCR. This is possibly due to the formation of copper phosphates in the large cages, as revealed using H2-TPR, which reduces the oxidation capacity. Moreover, results of XRD and27Al and31P solid-state NMR reveal that phosphorus not only interacts with copper by forming a P–O–Cu linkage but also partially inserts into the zeolite framework by forming a localized AlPO4phase. Both non-poisoned and P-poisoned catalysts lose their active sites and chabazite structures due to dealumination after successively aging in hydrothermal conditions (8 vol.% O2, 5 vol.% H2O in Ar) at different temperatures (800, 850, and 900 °C), which results in a large decrease in SCR performance. Specifically, the P-poisoned catalysts degrade faster than the non-poisoned catalysts. Results demonstrate that phosphorus induces the extensive formation of AlPO4that accelerates the dealumination during hydrothermal aging. This work provides new insight into understanding the deactivation mechanism in Cu-SSZ-13 from the perspectives of phosphorus-poisoning and hydrothermal aging, and it clearly shows that it is crucial to examine poisoning and hydrothermal aging simultaneously.

Hydrothermal aging

Cu/SSZ-13

Zeolites

Catalyst deactivation

Phosphorus-poisoning

Författare

Kunpeng Xie

Chalmers, Kemi och kemiteknik, Kemiteknik, Kemisk reaktionsteknik

Jung Won Woo

Chalmers, Kemi och kemiteknik, Kemiteknik, Kemisk reaktionsteknik

Diana Bernin

Chalmers, Kemi och kemiteknik, Kemiteknik, Kemisk apparatteknik

Ashok Kumar

Cummins Inc.

K. Kamasamudram

Cummins Inc.

Louise Olsson

Kompetenscentrum katalys (KCK)

Chalmers, Kemi och kemiteknik, Kemiteknik

Applied Catalysis B: Environmental

0926-3373 (ISSN) 1873-3883 (eISSN)

Vol. 241 205-216

Kompetenscentrum katalys KCK

Energimyndigheten, 2010-01-01 -- 2013-12-31.

Haldor Topsoe, -- .

Saab Automobile Powertrain AB, -- .

Volvo Group, -- .

Scania CV AB, -- .

Volvo Cars, -- .

ECAPS AB, -- .

Chalmers, -- .

Styrkeområden

Transport

Ämneskategorier

Annan kemiteknik

Annan kemi

Organisk kemi

DOI

10.1016/j.apcatb.2018.08.082

Mer information

Senast uppdaterat

2018-12-10