Selective conversion of cis-2-butene-1,4-diol to 2-hydroxytetrahydrofuran over K, Ca and Ba metals-promoted Ru/SiO2 catalysts: Role of the promoter

The effect of K, Ca and Ba metals addition on the catalytic properties of SiO2 supported ruthenium catalysts in the selective liquid phase conversion of cis-2-butene-1,4-diol affording, when hydrogenated, 2-hydroxytetrahydrofuran has been investigated. Catalysts containing 5 wt% Ru and promoted with a different amount of selected first and second group metals salts have been prepared and characterized by TPR, XRD, TEM, FT-IR of adsorbed pyridine and CO. It has been found that promoters modify the microstructural and electronic properties of Ru particles compared with those of the undoped Ru/SiO2 sample, depending on the metal nature and loading. Consequently, the catalytic activity and selectivity towards reaction products, in cis-2-butene-1,4-diol hydrogenation, is strongly affected by the presence of promoters.In particular, K-promoted systems give an excellent selectivity to 2-hydroxytetrahydrofuran but a poor activity; whereas group IIA metals salts addition leads to an enhancement of activity and a slight increase of selectivity to the desired product with respect to the bare Ru sample. The promoted Ru catalysts behaviour is discussed in terms of charge/ionic radius ratio effect of doping cations. Finally, the salient result is the maximum yield to 2-hydroxytetrahydrofuran of 80%, so far obtained, over the sample promoted with the highest potassium loading and mainly attributed to kinetic factors.

The effect of alkali and alkali earth promoters addition on the catalytic properties of 5% Ru/SiO2 catalyst in the selective conversion of cis-2-butene-1,4-diol to 2-hydroxytetrahydrofuran was investigated. The performance of the promoted catalysts is strongly affected by the metal nature and loading. The role of the promoters is discussed on the basis of the characterization data.Figure optionsDownload as PowerPoint slide