SAPO-34/5A Zeolite Bead Catalysts for Furan Production from Xylose and Glucose

Abstract

SAPO-34 zeolite crystals were grown on zeolite 5A beads, characterized, and then used to produce furfural from xylose and 5-hydroxymethylfurfural (HMF) from glucose. The SAPO-34/5A bead catalysts resulted in moderate furfural and HMF yields of 45% from xylose and 20% from glucose (463 K; 3 h) and were easier to recover than the SAPO-34 powder catalyst. At 463 K, the SAPO-34/5A beads were more selective than 0.02 M sulfuric acid for producing HMF and, unlike the sulfuric acid system, no levulinic acid was formed. The SAPO-34/5A bead catalysts had no significant loss in activity after three rounds of recycle when water washed or heated overnight between reactions; however, the heat-treated beads did show signs of thermal stress after the second reuse. The SAPO-34/5A bead catalysts show promise for dehydration reactions to produce furfural and HMF from xylose and glucose, respectively, and tailoring the catalyst and the support bead could lead to even higher selectivities and yields.

Impact of Xylose on Dynamics of Water Diffusion in Mesoporous Zeolites Measured by NMR

“…Despite the fact that application to nanoporous systems is challenging, due to the small structural length dimensions which generate complex rotational and translational molecular dynamics over a hierarchy of scales, significant characterization of systems such as zeolites has been attained [ 3 , 4 , 5 , 6 ]. The application of zeolites in catalytic conversion of biomass to fuel and chemical products is an area of growing application [ 7 ], and recent research has shown that zeolite beads have the potential to catalyze sugar to furan dehydration reactions [ 8 ]. Studies of water molecular dynamics in zeolites in the presence of biomolecules by NMR have been limited to solid state NMR spectroscopy, PGSE NMR using a single displacement observation time [ 9 ], and PGSE NMR to study water in zeolites [ 10 , 11 ] while solid state NMR has also been used to study solvents in zeolites [ 12 ].…”

“…Studies of water molecular dynamics in zeolites in the presence of biomolecules by NMR have been limited to solid state NMR spectroscopy, PGSE NMR using a single displacement observation time [ 9 ], and PGSE NMR to study water in zeolites [ 10 , 11 ] while solid state NMR has also been used to study solvents in zeolites [ 12 ]. Here displacement time-dependent PGSE NMR was applied to study the impact of xylose on water dynamics in zeolites for heterogeneous catalysis of sugars to furans [ 8 , 13 ].…”

“…Other researchers have looked at the use of powdered silicoaluminophosphates (SAPOs), a class of small-pore zeolites, in various solvent systems to maximize furfural production from xylose, achieving moderate yields [ 15 ]. In order to improve catalyst recovery, Romo et al used dual-layered zeolite beads (versus powdered zeolites) to convert xylose to furfural and achieved yields of up to 45%, indicating zeolite beads have the potential for sugar upgrading [ 8 ]. Although microporous zeolites beads are promising for sugar dehydration reactions, the zeolite pore size can create a diffusion limited system.…”

“…Commercially available Linde Type A (LTA) zeolite beads consist of ~3 μm crystallites made up of ~5Å molecular cages, which are compressed with binder into 3 mm beads that are 86% microporous [ 8 ]. Molecular transport in zeolite systems of this type of structure have been modeled as porous media with periodic permeable inclusions [ 6 , 19 , 20 ].…”

Ion-imprinted modified molecular sieves show the efficient selective adsorption of chromium(vi) from aqueous solutions

“…Zeolite molecular sieve 5A is a type of calcium ion exchange and synthetic bubble-zeolite, which possesses a larger specic surface area and more uniform aperture compared to a natural zeolite. [24][25][26][27] It is oen used as a gas adsorbent and catalyst support. (3-Aminopropyl)triethoxysilane (APTES) is a silane coupling agent with amino groups, which has been showing a good capacity towards the adsorption of Cr(VI) ions.…”