Lei L Zhou

Emission Performance of Lignin-Derived Cyclic Oxygenates in a Heavy-Duty Diesel Engine

In earlier research, a new class of bio-fuels, so-called cyclic oxygenates, was reported to have a favorable impact on the soot-NOx trade-off experience in diesel engines. In this paper, the soot-NOx trade-off is compared for two types of cyclic oxygenates. 2-phenyl ethanol has an aromatic and cyclohexane ethanol a saturated or aliphatic ring structure. Accordingly, the research is focused on the effect of aromaticity on the aforementioned emissions trade-off. This research is relevant because, starting from lignin, a biomass component with a complex poly-aromatic structure, the production of 2-phenyl ethanol requires less hydrogen and can therefore be produced at lower cost than is the case for cyclohexane ethanol. The goal of this paper, realized by means of experiments on a modified DAF heavy-duty diesel engine, is to investigate whether or not the (potentially prohibitively) expensive hydrogenation step from 2-phenyl ethanol to cyclohexane ethanol has an added value from an emissions perspective. The results suggest that this is not the case and hydrogenation therefore does not seem like an interesting additional step in the production process.

The Effect of the Position of Oxygen Group to the Aromatic Ring to Emission Performance in a Heavy-Duty Diesel Engine

In this paper the soot-NOx trade-off and fuel efficiency of various aromatic oxygenates is investigated in a modern DAF heavy-duty diesel engine. All oxygenates were blended to diesel fuel such that the blend oxygen concentration was 2.59 wt.-%. The oxygenates in question, anisole, benzyl alcohol and 2-phenyl ethanol, have similar heating values and cetane numbers, but differ in the position of the functional oxygen group relative to the aromatic ring. The motivation for this study is that in lignin, a widely available and low-cost biomass feedstock, similar aromatic structures are found with varying position of the oxygen group to the aromatic ring. From the results it becomes clear that both the soot-NOx trade-off and the volumetric fuel economy (i.e. ml/kWh) is improved for all oxygenates in all investigated work points. In general, the improvement in the soot-NOx trade-off correlated with the position of the functional oxygen group to the ring, with better overall emission behavior observed as the oxygen group was further from the ring. No distinct trend was observed with respect to fuel economy

Gasoline – ignition improver – oxygenate blends as fuels for advanced compression ignition combustion

Mixing is inhibited both by the relatively low volatility of conventional diesel fuel and the short premixing time due to high fuel reactivity (i.e. cetane number (CN)). Consequently, in this research two promising oxygenates which can be produced from 2 nd generation biomass -ethanol from cellulose and anisole from lignin - will be blended to gasoline, further doped with ignition improver. This will result in a diesel-like CN, but with a higher gasoline-like volatility. There is, however, also a more practical motivation for this study. In Europe, the dieselization trend is resulted in a growing excess of gasoline, which is currently largely exported to the USA at additional transport costs. Boosting the cetane number of gasoline into the diesel range with ignition improvers is a promising route to more efficiently consume European refinery products within Europe. In such a scenario and given current biofuel mandates, it is likely that biofuels will be added to the improved CN gasoline. Experiments are conducted on a modified in-line 6-cylinder DAF heavy-duty diesel engine. The goal of this paper is to assess the impact of a) fuel oxygen and b) oxygenate molecular structure on the effectiveness of the aforementioned advanced combustion concept with respect to engine efficiency and emission behavior. The results suggest that certain blends of 2- Ethylhexyl Nitrate (EHN) and oxygenates with gasoline can improve fuel efficiency and the soot-NOx trade-off compared to neat diesel fuel in conventional compressionignition combustion. Anisole is added to suppress soot emissions, based on positive findings in conjunction with diesel fuel in earlier work. EHN is subsequently supplemented to boost the gasoline blend CN into the diesel range. Improved efficiency is believed to be linked to the higher volatility of the gasoline blend . The improved soot-NOx trade-off is attributed to both higher volatility and the presence of fuel oxygen.