The oxidation of C2-C4 diols and diol/TPGME blends in a motored engine

Inspired by the announcement that liquid biofuel will be used nationally by 2020 in China, the autoignition of surrogates from hydrogenated biomass pyrolysis oil, namely, the C-2-C-4 diols, including ethanediol, 1,2-propanediol, and 1,2-butanediol has been studied using a modified CFR engine. From the oxidation process before critical compression ratio (CCR), it is observed that C-2-C-4 diols had similar oxidation reactivity as ethanol, indicating that C-2-C-4 diols had the potential for use as a supplement for ethanol. In addition, both of ethanol and C-2-C-4 diols did not display low temperature heat release. The ignition characteristics of C-2-C-4 diols suggest that diol/TPGME blends could be used, as TPGME has high ignition quality and could be generated from diols with a carbon selectivity as high as 75%. Based on this idea, diol/TPGME blends with volume ratio 20:80 were prepared and tested using the modified CFR engine. The blends showed strong low temperature oxidation behavior, even under a low intake temperature at 120 degrees C and a low compression ratio at 4, the low temperature heat release peak could still be found for the blends. Finally, the physical delay and chemical delay times were tested by a modified CID instrument between 540 and 640 degrees C, indicating that chemical process played a more important role on the combustion process than physical process, and the influence of temperature was more important for physical processes than chemical processes.