Table 5.

Performance of niobium-based catalysts for dehydration of fructose into HMF—from 2010 to date.

Entry	Catalyst	Solvent	t (h)	T (°C)	C (%)	S (%)	Y (%)	Experimental Conditions	Ref.
1	NbCl5	Ionic liquid	0.5	80	95	83	79	0.2 mmol catalyst; 1 mmol fructose in 10 mmol 1-butyl-3-methylimidozolium chloride, [bmim]Cl.	[154]
2	Nb2O5	Water	6	130	82	40	33	0.08 g catalyst; 0.60 g fructose; 60 mL water.	[155]
3	Sulfated Nb2O5	DMSO	0.17	120	96	75	72	0.018 g catalyst; 0.18 g fructose; 2 mL DMSO. After 5 h reaction the HMF yield reached 88%.	[156]
4	Nb2O5	DMSO	2	120	100	86	86	0.01 g catalyst; 0.56 mmol fructose; 5 g DMSO.	[157]
5	Nb2O5·H2O	Water/ 2-butanol	2	140	100	42	42	0.2 g catalyst; 2 mL of 1 wt% fructose; 5 mL 2-butanol.	[140]
6	Nb2O5·H2O treated with H3PO4	Water/ 2-butanol	0.83	160	90	99	89	0.10 g catalyst; 1.20 g fructose; 20 mL water and 30 mL 2-butanol; 800 rpm.	[139]
7	Niobium phosphate	Water	0.17	180	87	39	34	Fructose/catalyst mass ratio = 10; microwave was used.	[158]
8	Niobium phosphate	Water	0.5	130	58	78	45	0.8 g catalyst; 0.8 g fructose in 10 mL water.	[159]
9	Niobium phosphate	Water/acetone	0.91	138	78	64	50	20 g L−1 fructose; fructose/catalyst ratio = 1; acetone/water mass ratio = 1.	[163]
10	Niobium phosphate	Water/DMSO	5	140	95	95	90	10 wt.% catalyst; 1.0 wt% fructose; DMSO/water mass ratio = 1.5.	[159]
11	HNb3O8	Water	0.3	155	85	66	56	0.02 g catalyst; 1 g fructose; deionized water = 9 g. Microwave irradiation was used.	[164]
12	Nb2O5/Nb3O7(OH) modified with H2O2	DMSO	2	130	100	47	47	0.1 g catalyst; 10 mL of 20 g L−1 fructose.	[160]
13	Nb0.2-WO3	Water	2	120	100	30	30	0.1 g catalyst; 0.01 g fructose; 1 mL H2O.	[140]
14	NbPW (Nb/P molar ratio = 0.6)	DMSO	3	80	100	97	97	0.05 g catalyst; 56 mM fructose; 5 mL DMSO.	[161]
15	Nb-NTMPA	DMA	1.5	100	100	86	86	0.05 g catalyst; 0.1 g fructose; 2 g DMA, 0.2 g NaBr.	[165]
16	Nb-doped TiO2	Water	0.33	150	97	58	56	12.5 mg mL−1 catalyst; 0.55 mmol fructose; 15 W microwave irradiation.	[163]
17	Carbon/Nb2O5	DMSO	2	120	100	77	77	0.01 g catalyst; 0.1 g fructose; 5 g DMSO, 500 rpm.	[162]

NTMPA = nitrilotris(methylenephosphonic acid). DMA = N,N-dimethylacetamide.