Dehydration of Xylose into Furfural in the Presence of Crystalline Microporous Silicoaluminophosphates

Abstract

Microporous silicoaluminophosphates SAPO-5, SAPO-11 and SAPO-40 have been tested as solid acid catalysts in the dehydration of xylose into furfural (FUR) under biphasic aqueous-organic conditions, at 170°C. For all materials, no decrease in catalytic activity is observed after three consecutive recycling runs. Furfural yields at 4 h using SAPO-11 (34-38%) are comparable with that for HMOR zeolite with Si/Al * 6 (34%), under similar reaction conditions, while H 2 SO 4 (0.03 M) gives 2% FUR. Complete xylose conversion is reached within 16-24 h, with furfural yields of up to 65%. Brønsted and Lewis acidity of the silicoaluminophosphates was determined through FTIR analysis of adsorbed pyridine, and tentatively correlated with the catalytic performances.

Microwave-assisted coating of carbon nanostructures with titanium dioxide for the catalytic dehydration of d-xylose into furfural

“…These catalysts were found to be very stable, especially towards leaching of the active species under hydrothermal conditions and coke formation in comparison with several other solid catalysts reported in the literature, tested in the same reaction. 8,9,10,12 The two composites were effectively reused after a simple wash and drying procedure without decrease in Fur yields being observed during at least three batch runs (64-68% Fur yield). Catalytic nanomaterials with interesting performances may be prepared using this synthetic approach since it is very versatile, allowing the synthesis of a high variety of metal oxides, hybrid materials and composites (using different supports), as single or multifunctional catalysts (important for process intensification).…”

“…[8][9][10][11]13,14,16,17,19,47,48 The TiO 2 /CB catalyst allows reaching relatively high Fur yields in short reaction times (e.g. in comparison to H 2 Ti 3 O 7 nanosheets).…”

“…It was found that the reaction yield can be raised by removing the furfural from the aqueous phase immediately after its formation with, for instance, supercritical CO 2 7 or an organic extracting solvent. 8,9,11,12 This prevents furfural from being consumed in undesired secondary reactions typically taking place in the aqueous phase. In fact, very recently Huber and co-workers proposed a new process for the production of furfural using a two zone biphasic reactor (containing an extracting solvent), estimated to consume 67-80% less energy than the current industrial process.…”

Deactivation of solid catalysts in liquid media: the case of leaching of active sites in biomass conversion reactions

“…This type of treatment has been described in numerous scientific studies. [108][109][110] Note that the oxidation of adsorbed coke species by thermal treatment may not be possible if the catalyst is not stable at the required temperature or is 30 sensitive to oxidation. In the latter case gasification of the deposits can be also be achieved with other milder oxidants agents like waterH 2 O or even with inert or reducing agents like N 2 and H 2 .…”

“…33 Some of these thermal degradation processes can appear simultaneously. For example, high pressure and temperatures used in glycerol hydrogenolysis caused the collapse 110 of the porous network and sintering of the Cu metal particles in a silica-supported copper catalyst. 37 Apart from the mentionedse physical and thermal mechanisms, deactivation driven by chemical mechanisms can also take place.…”