C. Moreau et al., SELECTIVE PREPARATION OF FURFURAL FROM XYLOSE OVER MICROPOROUS SOLID ACID CATALYSTS, Industrial crops and products, 7(2-3), 1998, pp. 95-99
Dehydration of xylose into furfural was performed in a batch mode in t
he presence of I-I-form faujasites and mordenites as catalysts, at 170
degrees C and in a solvent mixture consisting of water and methylisob
utylketone or toluene (1:3 by volume). In toluene used as the co-solve
nt, xylose conversion and selectivity to furfural were found to depend
on both acidic and structural properties of the catalysts used, Under
the operating conditions used, H-mordenite with a Si/Al ratio of 11 w
as found to be more selective for the formation of furfural from xylos
e than H-Y faujasite with a Si/Al of 15. As already shown in the case
of the dehydration of fructose to 5-hydroxymethylfurfural, the better
selectivity of H-mordenite, as compared to H-Y faujasite, results from
the structural properties of these catalysts. The high selectivity ob
tained (90-95%) was correlated once again with the shape selective pro
perties of H-mordenites and particularly with the absence of cavities
within the structure allowing the further formation of secondary produ
cts. When methylisobutylketone is used as the co-solvent, lower select
ivities to furfural are obtained, in spite of the better affinity of f
urfural for methylisobutylketone than for toluene. Nevertheless, the h
igh selectivities obtained in a solvent mixture consisting of water an
d toluene then allow to consider a process of the kind previously desc
ribed for the dehydration of fructose. (C) 1998 Elsevier Science B.V.