Soot emissions from internal combustion engines is a significant environment issue and is leading to tightened particulate matter emission regulations across the world. Dimethoxymethane (DMM) is a promising renewable diesel fuel additive due to its low soot formation tendency and excellent solubility in diesel fuel. However, to make this blend commercially viable, some of DMM’s physical and chemical properties’ shortcomings, such as low calorific values, high water solubility, low flash point and high vapor pressure, need to be improved. This work aims to upgrade DMM properties via substituting the methyl end groups with butyl groups and by increasing the oxymethylene units in the molecule to form polyoxymethylene ethers (POMEs). Group contribution-based predictions were performed and show that the upgraded ethers (i.e. POMEs terminated with butyl groups) exhibit superior physical and chemical properties required for diesel fuel blending including higher heating values and reduced water solubility compared to DMM and methyl terminated POMEs, while still exhibiting remarkable cetane enhancement and soot reduction potential. One of the primary components of this study focuses on the synthesis of dibutoxymethane (DBM) using a batch reactor with commercially available cation exchange resins as catalyst. Among these resins, Amberlyst 15 had the best performance in terms of catalytic activity, stability and reusability. The adverse effect of presence of water in reaction solution was investigated and solutions such as pretreating the resins prior to use and adding molecular sieve for in-situ water absorption were proven to be effective. A pseudo-homogenous kinetic model was proposed to describe the end-group exchange reaction agreeing well with experimental data. Synthesis, characterization and pyrolysis kinetics studies of POMEs and its oligomers were also performed highlighting their potential as a diesel fuel bio-blendstock.

Cation exchange resins catalyzed synthesis of dibutoxymethane and polyoxymethylene dibutyl ether: A diesel fuel additive for soot reduction

ACS Fall 2020 Virtual Meeting

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