Synthesis of 5-hydroxymethylfurfural (HMF) by ..
Process for the synthesis of 5-hydroxymethylfurfural …
Although producing 2,5-dimethylfuran (DMF) from 5-hydroxymethylfurfural (HMF) is an attractive way to synthesize renewable fuels, achieving high yields for this reaction has proved difficult. PtCo bimetallic nanoparticle catalysts embedded in hollow carbon nanospheres now show improved catalytic performance for the hydrogenolysis of HMF to DMF (98% yield after 2 hours).
method for synthesis of hydroxymethylfurfural from sucrose
Obtaining HMF from glucose is, however, difficult because the direct synthesis of HMF from glucose usually proceeds in two steps. First, the isomerization of glucose to fructose occurs in the presence of enzyme, base, or metal chloride (Huang et al. 2010; Peng et al. 2012; Song et al. 2013; van Putten et al. 2013). Next, the fructose is dehydrated in the presence of an acid catalyst (H+) to yield HMF. The two-step process for producing HMF from glucose results in a low selectivity of HMF and a high amount of humins. Hence, the ideal strategy for the catalytic conversion of glucose into HMF requires a bifunctional catalyst that would affect both the isomerization of glucose to fructose and the subsequent dehydration of fructose. In recent years, a series of novel bifunctional catalysts have been synthesized, such as N,N‘-dimethylformamide (DMF), which combines Amberlyst-15 (a solid acid) and Mg–Al hydrotalcite (a solid base) for the one-pot synthesis of HMF from glucose (Takagaki et al. 2009). An HMF selectivity of 58% and a glucose conversion of 73% was achieved at 180 °C. In this catalytic system, the base acted as the catalyst for isomerizing the glucose into fructose, and the acid was the catalyst for dehydrating the fructose into HMF. In another instance, Cao et al. (2015) used an ammonium resin (PBnNH3Cl) as a single catalyst for the glucose and polysaccharide dehydration into HMF, with high selectivity (> 80%). This example demonstrated, through decomposing ammonium resin under the high reaction temperature, that the in situ formation of –NH2 (PBnNH2) and H+ (HCl) could act as both the isomerizing agent for glucose and the acid catalyst for the dehydration of fructose. However, the procedures for preparing bifunctional catalysts are tedious and cumbersome, although these catalysts display high catalytic performance and recyclability, and using a commercially available commodity as the bifunctional catalyst would be preferred.