Marine Catalysts

Exposure to high levels of air pollution can cause a variety of adverse health outcomes. Among air pollutants, Sulphur Oxides (SO_x), remarkably Sulphur Dioxide (SO₂), are emitted when fuels containing sulphur are combusted. The SO₂ emissions have been related with significant environmental and human health effects such as acid rain, the greenhouse effect, photochemical pollution, eutrophication, respiratory and cardiovascular diseases.

Globally, SO₂ emissions from marine fuel are estimated to contribute to around 13% of the global anthropogenic emissions
of SO₂. Since 2020, the International Maritime Organisation (IMO) has limited sulphur content in ships’ fuel oil to a maximum 0.50% and 0.1% in the ECA (Emission Control Area) zones.

Although fuels with low sulfur content currently are available, HFO is still the mostly consumed fuel due to its significantly lower cost. To this end, commercial solutions for the reduction of SO₂ emissions of engines utilising HFO have been developed, such as scrubbers which utilise sea water by spraying it into the SO_x rich exhaust gas stream, and discharge it overboard, without treatment in most of the cases. In this way, the problem of air pollution is transferred to the sea.
Due to the large volume of solid waste produced from such systems along with their high cost, large installation size and complex operation, scrubbers have not yet received adequate acceptance.

MONOLITHOS has developed a disruptive solution for the catalytic reduction of sulfur dioxide (SO₂) from gaseous internal combustion engines that operate on Heavy Fuel Oil (HFO) with high sulfur content, via its conversion to elemental sulfur that can be stored on board.

In specific, MONOLITHOS develops advanced heterogeneous nanocatalysts that will reduce SO₂ emissions from ship’s flue gases that use HFO, by converting them to elemental sulfur. In particular, SO₂ is catalytically reduced to elemental sulfur through chemical reactions utilising CO, C_xH_y and NO_x, which are already present in the flue gas emissions.
Fe and Cu based catalyst, supported on mixed oxide CeZr substrate are employed for the gas treatment.

Finally, the developed catalyst is being retrofitted in the engine exhaust stream, working on an appropriate temperature in line with a catalytic particulate filter (catalyzed diesel particulate filter, C-DPF) which will also treat particulate matter
of the gas stream.