Knock Resistance and Fine Particle Emissions for Several Biomass-Derived Oxygenates in a Direct-Injection Spark-Ignition Engine

Abstract

Several high octane number oxygenates that could be derived from biomass were blended with gasoline and examined for performance properties and their impact on knock resistance and fine particle emissions in a single cylinder direct-injection spark-ignition engine. The oxygenates included ethanol, isobutanol, anisole, 4-methylanisole, 2-phenylethanol, 2,5-dimethyl furan, and 2,4-xylenol. These were blended into a summertime blendstock for oxygenate blending at levels ranging from 10 to 50 percent by volume. The base gasoline, its blends with p-xylene and p-cymene, and high-octane racing gasoline were tested as controls. Relevant gasoline properties including research octane number (RON), motor octane number, distillation curve, and vapor pressure were measured. Detailed hydrocarbon analysis was used to estimate heat of vaporization and particulate matter index (PMI). Experiments were conducted to measure knock-limited spark advance and particulate matter (PM) emissions. The results show a range of knock resistances that correlate well with RON. Molecules with relatively low boiling point and high vapor pressure had little effect on PM emissions. In contrast, the aromatic oxygenates caused significant increases in PM emissions (factors of 2 to 5) relative to the base gasoline. Thus, any effect of their oxygen atom on increasing local air-fuel ratio was outweighed by their low vapor pressure and high double-bond equivalent values. For most fuels and oxygenate blend components, PMI was a good predictor of PM emissions. However, the high boiling point, low vapor pressure oxygenates 2-phenylethanol and 2,4-xylenol produced lower PM emissions than predicted by PMI. This was likely because they did not fully evaporate and combust, and instead were swept into the lube oil.

Impacts of dimethyl carbonate blends on gaseous and particulate emissions from a heavy-duty diesel engine

“…There is a growing interest in the use of renewable oxygenated fuels either as replacements of, or additives to, petroleum-based transportation fuels in internal combustion engines. Oxygenated biofuels, such as ethanol and fatty acid methyl esters, are attractive because they offer greenhouse gas (GHG) emission benefits, reduce the tendency to form soot and black carbon emissions, help address climate change, and reduce the dependence on fossil fuel resources [7][8][9]. Carbonate esters (which consist of a carbonyl group connecting two alkyl groups) are promising fuels for use in compression ignition engines [10,11].…”

Modeling study of the anti-knock tendency of substituted phenols as additives: an application of the reaction mechanism generator (RMG)

“…In the following sections, the above method will be applied to predict the anti-knock tendency of several substituted phenols, which are important products derived from the pyrolysis oil of lignocellulosic-biomass and have the potential to be used as drop-in fuels or fuel additives. [20][21][22] The methodology for model generation is introduced first. The base fuel model is validated with the literature data, and the effect variable volume condition has on base fuel chemistry is discussed.…”

Emission of Carbonyl and Polyaromatic Hydrocarbon Pollutants From the Combustion of Liquid Fuels: Impact of Biofuel Blending

“…Nevertheless, exhaust emissions released into the atmosphere lead to major environmental and health concerns. Some polluting constituents such as carbon monoxide, nitrogen oxides, unburned hydrocarbons, and particulate matter [14,15] are strictly regulated by governments. However, other exhaust constituents, generally referred to as unregulated pollutants, have significant impact on atmospheric pollution and human health.…”