Insights of Selective Catalytic Reduction Technology for Nitrogen Oxides Control in Marine Engine Applications

The international shipping industry is facing increasingly stringent limitations on nitrogen
oxide (NOx) emissions. New solutions for reducing NOx emitted by marine engines need to be
investigated to find the best technology. Selective Catalytic Reduction (SCR) is an advanced active
emissions control technology successfully used in automotive diesel engines; it could be applied to
marine engines with ad-hoc solutions to integrate it in the exhaust of large engines. In this study,
a commercial SCR was tested at the exhaust of a diesel engine in inlet gas conditions typical of a
marine engine. The SCR system consisted of a custom monolith (provided by Hug-Engineering AG)
that enabled seamless integration for a broad range of engine sizes; the active phases were V2O5
(3 wt%)-WO3
(7 wt%)-TiO2
(75 wt%). The monolith was studied at the laboratory scale for its in-depth
chemical/physical characterization and by means of an intermediate-scale engine, reproducing the
exhaust gas conditions of a full-scale marine engine. The system's effectiveness in terms of NOx
removal for the selected engine operating conditions was evaluated in a wide range of temperature
and NOx emissions values and for different quantities of the reduction agent (AdBlue or ammonia)
added to exhaust gases. The investigated technological solution resulted in efficient NOx emission
control from a marine engine