Catalytic etherification is a new and developing method for the upgradation of pyrolysis bio-oil into high performance bio-based long-chain ethers. In this work, the application of bio-based long-chain ether oxygenated additives in diesel engines have been checked by focusing on their regulated emissions and PAH emissions. Four bio-based long-chain ethers with similar structures, including: Polyoxymethylene dimethyl ether , diglyme , dipropylene glycol dimethyl ether and tripropylene glycol methyl ether have been blended with diesel fuel and tested in a small-duty diesel engine. The results showed that long-chain ethers were beneficial to the reduction of regulated emissions by comparing to pure diesel. Polyoxymethylene dimethyl ether and tripropylene glycol methyl ether showed best performance among the four tested ethers. Polyoxymethylene dimethyl ether could reduce 56% CO, 23% NO and 93% soot emissions, while Tripropylene glycol methyl ether could reduce 52% CO, 28% NO and 88% soot emissions. Besides, the particle sizes of soot particles from the blended fuels were also reduced. What's more, the addition of bio-based long-chain ethers could reduce particulate PAHs emissions by 39% ~ 67% and reduce gaseous PAHs emissions by 25% ~ 44%, and the PAHs toxicity was also reduced by 32% ~ 55%. This work proved that the structure of oxygen atoms evenly distributed in the chain could efficiently suppress the production of soot precursors and eventually reduce the soot emission
A novel valorization pathway for steam-exploded corn stalk conversion to long-chain ethers was proposed in the work. The procedure enabled the transformation of multifunctional components in catalytic fast pyrolysis (CFP) vapors using Fe-Ce mixed oxides into carbonyl compounds (ketones, aldehydes and furans with carbonyl group) suitable for preparing long-chain oxygenated fuels in a fluidized-bed/fixed-bed consolidation reactor. A series of Fe-Ce bimetallic oxides were explored and the results indicated that the catalyst with 0.3 of molar ratio of Fe to Ce (Fe/Ce(0.3)) showed highly active in converting levoglucosan and acetic acid into linear and cyclic ketones . Moreover, the conversion rate of acetic acid and levoglucosan in pyrolytic vapors was close to 100% and 90.07%, respectively. The carbon yield of carbonyl compounds (28.91%) in ex-situ CFP was achieved under optimal conditions. The continuous operation showed that Fe/Ce(0.3) remained highly active and there was little coke and carboxylates on the catalyst surface after 200 min.
Incomplete diesel combustion emits soot and CO. The use of biomass-derived, oxygen-containing diesel additives has been proposed as an effective mitigation strategy. Among these, long-chain ethers have been widely regarded as one of the most promising additive classes. Guided by this, carbonyl compounds were targeted as intermediates for the synthesis of long-chain ethers. Py-GC/MS was used to assess eight oxides (CaO, ZrO2, NiO, CeO2, TiO2(rutile), TiO2(anatase), Fe2O3, CuO) during fast pyrolysis of native holocellulose. Relative content of carbonyl compounds was increased by all catalysts, with CaO exhibiting the highest value (69.47%). CaO raised the content of linear ketones from 18.25% to 27.61%, while it sharply reduced the relative content of acetic acid (from 11.56% to 3.19%). TiO2(rutile) increased cyclic ketones from 11.09% to 15.01%. CuO boosted furans and acids to 17.48% and 17.91%, respectively. Levoglucosan dropped from 11.24% to 4.83% over CuO, which also increased furfural content from 3.25% to 5.63%.
The work introduced an innovative pathway for converting biomass-derived carbonyls into long-chain ethers, examining their low-temperature oxidation in a modified Cooperative Fuel Research (CFR) engine. The conversion of 2-butanone achieved 100 % and the selectivity of sec -butyl isopropyl ether reached the maximum of 83.13 % under optimal reaction conditions. Conversion of biomass-derived carbonyls increased from 31.77 % at 1 h to 36.28 % at 12 h, with the mass yield of long-chain ethers rising from 53.94 % to 62.86 %. At the same compression ratio, the maximum in-cylinder pressure and temperature increased as the long-chain ethers blending ratio increased. At the critical compression ratio, the net heat release rates (NHR) for blended fuels with 10 vol%, 20 vol% and 30 vol% long-chain ethers at the low-temperature heat release peak were 9.6 J/deg, 10.1 J/deg, and 10.0 J/deg better than that of n -heptane (6.3 J/deg), respectively. CO emissions from blended fuels before compression ignition were higher than n -heptane, while the value for the blended fuel with 30 vol.% long-chain ethers was reduced by 44.97 % compared to n -heptane after autoignition.
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