Dehydration of xylose

As previously stated, furfural is obtained through dehydration of pentoses, xylose in particular, or hemicelluloses, at high temperatures (200-250 °C), and in the presence of mineral acids as catalysts, mainly sulfuric acid.[31] Under these 

In the presence of the H-Mordenite with a Si/Al ratio of 11 as catalyst, a close parallelism is observed with the results obtained for the dehydration of fructose, except that toluene is the co-solvent instead of methyl isobutyl ketone. The transformation of xylose into furfural is easily achieved at 170 °C with a selectivity as high as 90 to 95% as far as the conversion is kept at a low extent, 30 to 40%.[33] At those high temperatures, ion-exchange resins cannot compete with zeolites. 

---

A delaminated zeolite with an Si/Al ratio of 29, derived from the layered zeolite Nu-6(1), was employed as catalyst for dehydration of xylose at 170 °C, using a water-toluene biphasic reactor-system.140 This material, designated del-Nu-6(l), proved to be efficient for this transformation, giving 47% selectivity to furfural at 90% xylose conversion. 

Xylose. Catalytic dehydration of xylose, which is the most abundantly available pentose monomer in hemicellulose, has been known for a long time (Scheme 5). In fact, as early as 1922, an industrial process involving sulfuric acid catalyzed dehydration of xylose to produce furfural was developed by the Quaker Oats Co. 

Furfural. Dehydration of xylose, available from biorefinery hemicellulose, leads to the production of furfural.462 64... 

Dias, A. S., Pillinger, M., and Valente, A. A., Dehydration of xylose into furfural over micro-mesoporous sulfonic acid catalysts. J Catalysis 2005, 229 (2), 414-423. 

Dias, A.S., Lima, S., Pillinger, M., Valente, A.A. 2006. Acidic cesium salts of 12-tungsto-phosphoiic acid as catalysts for the dehydration of xylose into furfural. Carbohydrate Research 341 2946-2953. 

The dehydration of xylose in aqueous solution catalysed by a Cp2TiCl2-protoporphyrin complex immobilised in a polyacrylamide gel has been studied, and rate constants activation parameters for this process have been determined, and a thermodynamic investigation of the hydrolysis of sucrose by microcalorimetry and h.p.l.c. has been reported. ... 

Taking into account the above statements, the following section will discuss the catalytic performances of nanofluorides in some applications on biomass valorization such as the cellulose hydrolysis to glucose [145], cellulose valorization to lactic acid [146], and the valorization of glycerol (i.e., the by-product of biodiesel production) to synthesis of diacyl and triacyl glycerine [147], but also the dehydration of xylose and glucose to furan derivatives [148,149]. 

O NeiU R, Ahmad MN, Vanoye L, Aiouache E. Kinetics of aqueous phase dehydration of xylose into furfural catalyzed by ZSM-5 zeohte. Ind Eng Chem Res 2009 48 4300-6. 

Lima S, Fernandes A, Antunes M, Pillinger M, Ribeiro F, Valente A. Dehydration of xylose into furfural in the presence of crystalline microporous silicoaluminophosphates. Catal Lett 2010 135 41-7. 

Antunes MM, Lima S, Fernandes A, PiUinger M, Ribeiro MF, Valente AA. Aqueous-phase dehydration of xylose to furfural in the presence of MCM-22 and lTQ-2 solid acid catalysts. Appl Catal A 2012 417-418 243-52. 

Pholjaroen B, Li N, Wang Z, Wang A, Zhang T. Dehydration of xylose to furfural over niobium phosphate catalyst in biphasic solvent system. J Energy Chem 2013 22 826-32. 

Sddaba I, Lima S, Valente AA, Lopez Granados M. Catalytic dehydration of xylose to furfural vanadyl pyrophosphate as source of active soluble species. Carbohydr Res 2011 346 2785-91. 

Suzuki T, Yokoi T, Otomo R, Kondo JN, Tatsumi T. Dehydration of xylose over sulfated tin oxide catalyst influences of the preparation conditions on the structural properties and catalytic performance. Appl Catal A 2011 408 117-24. 

---