The etherification of 5-hydroxymethyl-2-furfural (HMF) with ethanol is studied over a series of mesoporous silica catalysts (Al-MCM-41 materials with different Si/Al ratio, and zirconia or sulfated zirconia supported over SBA-15) and compared with the behavior of H₂SO₄ and Amberlyst^®15. The observed reaction products were 5-(ethoxymethyl)furan-2-carbaldehyde (EMF), 1,1-dietoxy ethane (DE) and ethyl 4-oxopentanoate (EOP). The selectivity to EMF and EOP is closely related to the presence of Lewis and/or Brønsted acidity on the catalyst, while the formation of DE is probably related to defect sites. The latter, being less reactive, catalyze the side reaction to DE only when strong Lewis and/or Brønsted acid sites are absent. Catalysts with only a strong Brønsted acidity react selectively to form EOP. When strong Lewis acid sites are present in the catalyst, e.g. by introducing ZrO₂ in SBA-15 or when extra-framework isolated Al³⁺ sites are present in the mesoporous channels, a high selectivity to EMF was observed. The results indicate that EMF, DE or EOP can be obtained selectively by direct reaction of HMF with bioethanol by tuning the acidity of the catalyst. EMF is a value biodiesel component, but the results also evidence the possibility to obtain selectively EOP in a one-step reaction, opening interesting perspectives to produce valeric biofuels by subsequent selective hydrogenation.

在一系列介孔二氧化硅催化剂（具有不同Si / Al比的Al-MCM-41材料以及负载在SBA-15上的氧化锆或硫酸化氧化锆）上研究了5-羟甲基-2-糠醛（HMF）与乙醇的醚化反应；用H的行为相比，₂ SO ₄和Amberlyst ^®15.观察到的反应产物是5-（乙氧基甲基）呋喃-2-甲醛（EMF），1,1-二乙氧基乙烷（DE）和4-氧戊酸乙酯（EOP）。对EMF和EOP的选择性与催化剂上路易斯和/或布朗斯台德酸度的存在密切相关，而DE的形成可能与缺陷位点有关。后者的反应性较低，仅在不存在强路易斯和/或布朗斯台德酸位时才催化与DE的副反应。仅具有强布朗斯台德酸度的催化剂选择性地反应形成EOP。当催化剂中存在强路易斯酸位时，例如通过在SBA-15中引入ZrO ₂或当骨架外分离Al ^3+时位点存在于介孔通道中，观察到对EMF的高选择性。结果表明，通过调节催化剂的酸度，HMF与生物乙醇直接反应可以选择性地获得EMF，DE或EOP。EMF是有价值的生物柴油成分，但结果也证明了一步反应选择性获得EOP的可能性，为通过随后的选择性加氢生产戊酸生物燃料开辟了有趣的前景。