Styrene, or ethylbenzene, is mainly used as a monomer for the production of polymers, most notably Styrofoam. In the synthetis of styrene, the feedstock of benzene and ethylene is converted into aromatic oxygenates such as benzaldehyde, 2-phenyl ethanol and acetophenone. Benzaldehyde and phenyl ethanol are low value side streams, while acetophenone is a high value intermediate product. The side streams are now principally rejected from the process and burnt for process heat. Previous in-house research has shown that such aromatic oxygenates are suitable as diesel fuel additives and can in some cases improve the soot-NOx trade-off.
In this study acetophenone, benzaldehyde and 2-phenyl ethanol are each added to commercial EN590 diesel at a ratio of 1:9, with the goal to ascertain whether or not the lower value benzaldehyde and 2-phenyl ethanol can perform on par with the higher value acetophenone. These compounds are now used in pure form. In future work, real streams, which are rich of these compounds, but contain various other chemicals as well, will be used.
Experiments have been performed on a heavy duty (12.6L) diesel engine, of which one cylinder is a dedicated test cylinder. The results demonstrate that the emissions and efficiencies are more or less comparable for all aromatic oxygenates. Afterwards, the results are compared against neat diesel. It was found that, depending on operation conditions, either the efficiency of the oxygenates was higher, while the emissions where comparable to diesel or the emissions decreased dramatically with comparable efficiencies as diesel. Accordingly, compared to neat diesel, both the high- and low-value styrene streams yield overall positive engine behavior in all measured operating conditions.