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

Abstract

The reduction of emissions from diesel engines has been one of the primary elements in obtaining improvements in air quality and greenhouse gas reduction goals. Dimethyl carbonate (DMC) is an oxygenate fuel that can be used in petroleum diesel that is been lightly studied, but could provide significant reductions in particulate matter (PM) emissions from internal combustion engines. This study evaluated the emissions impacts of 5%, 12.5%, 20%, and 30% blends of DMC in a California diesel fuel. DMC showed PM reductions increased with increasing DMC blend levels, ranging from 30% to 78% for the DMC5 to DMC30 blends. In contrast, particle number emissions increased with increasing DMC levels, which could be attributed to the enhanced formation of small nucleation particles as the levels of larger accumulation particles were reduced. NO x emissions showed increases of 3.2% and 3.1%, respectively, for the higher 20% and 30% blends, but no statistically significant differences for the 5% and 12.5% blends. Carbon monoxide (CO) emissions showed strong reductions from 26.3% to 60.9% with DMC blending, while total hydrocarbons (THC) emissions showed increases from 32.5% to 137% with DMC. Most of the hydrocarbon species showed increases with increasing DMC blend levels, including benzene and most mono-aromatic hydrocarbons. Similarly, formaldehyde and acetaldehyde showed statistically significant increases with DMC blending relative to diesel fuel. The carbon dioxide (CO 2) emissions and brake specific fuel consumption (BSFC) increased with increasing DMC blend levels compared to diesel fuel.

Evaluation of Dimethyl Carbonate as Alternative Biofuel. Performance and Smoke Emissions of a Diesel Engine Fueled with Diesel/Dimethyl Carbonate/Straight Vegetable Oil Triple Blends

“…In this sense, the radical CH 3 OC • = O from DMC decomposition usually leads to the formation of CO or CO 2 . Likewise, oxygenated fuels increase the formation of free radicals such as • O and • OH that promote the oxidation of unsaturated species, which are soot precursors [22]. On the other hand, in particular for the case of dimethyl carbonate, the absence of C-C bonds in its structure reduces the formation of acetylene and benzene, which are species that lead to the formation of polycyclic aromatic hydrocarbons (PAHs), which are soot precursors [22,29].…”

“…In this line, dimethyl carbonate is highlighted as a potential biofuel not only because of its non-toxic and biodegradable nature, but also because of its suitable properties for achieving a good performance in diesel engines, including high miscibility with diesel fuel, low boiling point and high oxygen content (53% by weight). Furthermore, the absence of carbon-carbon bonds in the dimethyl carbonate (DMC) molecule would contribute to hydrocarbon oxidation, which limits its participation in soot growth reactions [22]. Although DMC is industrially produced through different routes, e.g., phosgenation, transesterification or oxidative carbonylation of methanol using O 2 , another low-cost and higher efficiency alternative route that implies the use of CO 2 as feedstock, is under study [23].…”

“…In recent years, DMC has been intensively studied as an effective biofuel and additive for diesel fuel [22,[26][27][28][29][30][31][32][33][34]. This oxygenated compound has been tested in blends with biodiesel [35,36] and in biodiesel/diesel blends [37].…”

“…engines [22,[26][27][28][29][30][31][32][33][34][35][36][37]. However, DMC has only been applied as an additive in small proportions to diesel, biodiesel or their blends because of its low calorific value that reduces the energy density of fuel mixtures, which represents the most important limitation of this methodology to reach high levels of fossil fuel substitution.…”

Biodiesel at the Crossroads: A Critical Review

“…These emissions were reduced by up to 50% with a 96% diesel and 4% DMC blend. A DMC and diesel blend may also have potential in the reduction of yet unregulated carcinogenic emissions such as benzene and 1,3-butadiene [250][251][252][253][254]. Similarly to these processes, the use of diethyl carbonate (DEC) instead of DMC has been much less investigate [221,227,234], although the available results in literature [255][256][257][258][259][260][261][262][263][264][265][266] allow us to conclude that they exhibit a behavior very similar to those obtained with DMC.…”