Model-Based Design of Tailor-Made Biofuels

Abstract

Oxygenates derived through the selective catalytic refunctionalization of carbohydrates of lignocellulosic biomass can be tailored to exhibit desired physicochemical fuel properties that unlock the full potential of advanced internal combustion engines. Considering the fuel’s molecular structure to be a design degree of freedom, we present a framework for model-based fuel design that is envisioned to guide experimental investigation toward the most promising molecular entities. Following a generate-and-test approach to computer-aided molecular design, a novel rule-based generator of molecular structures is introduced to refunctionalize and join molecular graphs of predefined biobased intermediates in an attempt to resemble carbon- and energy-efficient biofuel synthesis. Computational property prediction is employed to virtually screen the generated structures with regard to key physicochemical fuel properties, e.g., the derived cetane number or fuel volatility. Two case studies are dedicated to the identification of biofuel components for use in (i) spark-ignition and (ii) compression-ignition engines.

Identification of Promising Alternative Mono-Alcohol Fuel Blend Components for Spark Ignition Engines

“…Design methodologies can avoid expensive and time-consuming trial-and-error experimental campaigns. Similar approaches have been successfully used in several fuel development projects [4,[53][54][55][56][57][58][59][60], typically to design tailor-made molecules for fuel application. That is, molecular building blocks were computationally joined and reassembled to generate new molecules with good fuel blendstock potential.…”

“…Since fuel properties are vitally important for enabling SI engines to run at high efficiencies and with low emissions, several countries have started initiatives to develop, in tandem, advanced fuels, and advanced engines. Two examples are the Co-Optima program funded by the US DOE in the US [3] and the Tailor-Made Fuels from Biomass initiative in Germany [4].…”

Electrochemical cross-coupling of biogenic di-acids for sustainable fuel production

“…To make a first assessment of their suitability as tailor-made fuels, we consider two properties of paramount importance to smooth engine operation: auto-ignition quality and volatility. 43 Table 1 compares the normal boiling points of the synthesized compounds to the boiling ranges of typical fossil-based gasoline and diesel fuels. In spark-ignition (SI) engines, low fuel volatility can lead to problems when starting the engine at cold conditions.…”

“…44 Fuel auto-ignition quality can be used to differentiate between fuels for SI and CI engines. 43,48,49 Because in SI engines the ignition event is controlled by the spark plug, the fuel/air mixture has to withstand auto-ignition in the so-called end gas, i.e., those parts of the charge that have not yet been reached by the flame. The phenomenon of undesired auto-ignition in SI engines is referred to as engine knock and severely limits SI engine efficiency.…”

“…Due to its relatively high boiling point, we do not expect TBI to be a pure compound fuel, not even in a tailor-made SI combustion system. 43,62 However, TBI could be attractive as an octane booster component for blending with fossil or renewable base fuels. Small esters, specifically methyl acetate and ethyl acetate, have been found to effectively increase the RON of gasoline.…”