Mesoporous tantalum phosphates: preparation, acidity and catalytic performance for xylose dehydration to produce furfural

Abstract

Mesoporous tantalum phosphates (TaOPO 4 -m) with varying P/Ta molar ratios (m ¼ 0.41-0.89) were prepared, comprehensively characterized by ICP-AES, N 2 physisorption, small-angle XRD, TEM, Raman, FT-IR, NH 3 -TPD and IR of pyridine adsorption and employed to catalyze the dehydration of xylose to produce furfural in a biphasic batch reactor. The physicochemical properties of these TaOPO 4 -m samples were affected significantly by variation of m. More ordered mesopores were formed in the sample with a higher m. On the other hand, the density of acidity decreased but the ratio of Brønsted acidity to Lewis acidity (B/L) increased with the increase in m. TaOPO 4 -0.84, which showed adequate mesoporosity and a high B/L ratio, was identified as the best performing catalyst among these TaOPO 4m catalysts in terms of high furfural selectivity (ca. 72 mol%). Correlating the catalyst performance with its acid property showed that the xylose consumption rate decreased with the increasing B/L ratio, while furfural selectivity showed a volcano-type dependence on the B/L ratio. Besides, the huge decrease in the furfural selectivity after poisoning the Brønsted acid sites by adding 2,6-dimethyl pyridine revealed a kind of Brønsted acid catalysis for selective furfural production. Fig. 7 Performance of the TaOPO 4 -m catalysts with different molar P/Ta ratio m by the time courses of (A) xylose conversion, (B) furfural selectivity: m ¼ 0.41 (-), m ¼ 0.61 (B), m ¼ 0.75 (:), m ¼ 0.84 (A), and m ¼ 0.89 (P).This journal is

Hydrolysis of Hemicellulose and Derivatives—A Review of Recent Advances in the Production of Furfural

“…Eventually, another tentative use of phosphates as heterogeneous catalyst for biomass dehydration was targeting a synergistic effect of tantalum (Li X.-L. et al, 2015 ). In this regard, different mesoporous tantalum phosphates (TaOPO 4 -m) with various P/Ta molar ratios were prepared and tested for evaluating their respective catalytic activities to convert D-xylose into furfural (Xing et al, 2016 ). A high Bronsted to Lewis acid site ratio is required to enhance the furfural selectivity.…”

Effective conversion of biomass into bromomethylfurfural, furfural, and depolymerized lignin in lithium bromide molten salt hydrate of a biphasic system

“…19,[23][24][25] HMF and FF are typically produced from acidinduced dehydration of hexoses and pentoses, respectively, using homogeneous mineral acids or heterogeneous acids as catalysts in aqueous or organic solvents. 17,[26][27][28][29] However, the production of these furans remains challenging due to low yield, poor selectivity, and environmental issues of the associated processes. 5 Currently, the annual FF production is more than 200 000 tons worldwide, but the current yield is only about 50% of the theoretical yield due to the aforementioned side reactions.…”

“…[31][32][33][34][35] Diverse approaches were explored, but these processes had some limitations such as high acid loading or concentration, unsatisfactory product yield, and insufficient utilization of hemicelluloses and lignin. 26,27,29,31,32 For effective conversion of biomass to the furans, selection of a proper reaction medium is crucial. In the previous studies, water with acid catalyst was the most common medium, but low yield and poor selectivity are the major issues due to the rehydration of HMF to levulinic acid and formic acid and/or the condensation of the furans to humins.…”

Catalytic Conversion of Bamboo Meal to High‐Yield Furfural With Solid Acid Catalyst FePO4⋅2H2O

“…Compared to mineral acid H 2 SO 4 (Brønsted acid, pH=1) and solid acid catalyst PTSA‐POM (Brønsted acid), the furfural yield by FePO 4 catalytic decreased by 6.7% and 1.9%, respectively. In attention, the furfural yield under FePO 4 catalyst was higher than most of mineral acid (Brønsted acid, H 3 PO 4 , HCl, H 2 SO 4 with pH=2), metal chlorate FeCl 3 ⋅6H 2 O (Lewis acid), solid acid catalyst S‐RFC (Brønsted acid) and SO 4 2− /SnO 2 − MMT (Brønsted/Lewis acid) . Compared to the liquid acid catalyst (such as mineral acid and metal chlorate), the FePO 4 catalyst with both contained Brønsted/Lewis acid sites, provided an effective catalytic activity for furfural production.…”

“…In attention, the furfural yield under FePO 4 catalyst was higher than most of mineral acid (Brønsted acid, H 3 PO 4 , HCl, H 2 SO 4 with pH = 2), metal chlorate FeCl 3 ·6H 2 O (Lewis acid), [15] solid acid catalyst S-RFC (Brønsted acid) [36] and SO 4 2 À /SnO 2 À MMT (Brønsted/Lewis acid). [37] Compared to the liquid acid catalyst (such as mineral acid and metal chlorate), the FePO 4 catalyst with both contained Brønsted/ Lewis acid sites, provided an effective catalytic activity for furfural production. This advantage was also proved by the yields of levulinic acid and 5-hydroxymethyl furfural, which were higher than those were obtained by all the liquid acid catalyst.…”