Directional Transformation of Native Holocellulose into Long-Chain Ether Fuel Precursors over Metal Oxides

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%.