title: Functional relationship of furfural yields and the hemicellulose-derived sugars in the hydrolysates from corncob by microwave-assisted hydrothermal pretreatment.
abstract: BACKGROUND
  Corncob as one of the most suitable feedstock for the production of a variety of high-value-added chemicals is receiving increasing attention worldwide because of the characteristics of high carbohydrate (cellulose and hemicelluloses) contents and high energy densities. Furfural produced from hemicelluloses is a highly versatile and key feedstock used in the manufacture of a wide range of biofuel and important chemicals in different fields. Achieving high furfural yields from corncob combining green approaches and efficient equipment has the promising potential for biomass-to-biofuel technologies. To understand the dissolving mechanism of corncob sugars and reveal the relationship between the hydrolysate composition and furfural yields, a two-step approach was proposed using microwave-assisted hydrothermal pretreatment and subsequently heterogeneous catalytic process.
  
  
  RESULTS
  Released hemicelluloses in the first stage were mainly in forms of monosaccharide, oligosaccharides, and water-soluble polysaccharide. Hydrolysates with the maximum xylose content (99.94 mg g(-1), 160 °C, 90 min), the maximum xylobiose content (20.89 mg g(-1), 180 °C, 15 min), and the maximum total xylose content in monosaccharide and oligosaccharides (DP ≤ 6) (272.06 mg g(-1), 160 °C, 60 min) were further converted to furfural using tin-loaded montmorillonite as the catalyst in a biphasic system. The highest furfural yield (57.80 %) was obtained at 190 °C for 10 min from hydrolysates with the maximum xylose content. Moreover, controlled experiments showed that furfural yields from corncob hydrolysates were higher than those from the pure xylose solutions, and lower initial xylose concentration may be in favor of the furfural production.
  
  
  CONCLUSIONS
  This work provides an efficient approach to produce furfural by a two-step process for the biomass-to-biofuel industry. Results indicated that the production of furfural from biomass raw materials can be controlled by the depolymerization degree of hemicelluloses.
authors: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, 510640 China.
authors: Huiling
authors: H
authors: Li
authors: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, 510640 China.
authors: Xiaofeng
authors: X
authors: Chen
authors: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, 510640 China.
authors: Junli
authors: J
authors: Ren
authors: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, 510640 China.
authors: Hao
authors: H
authors: Deng
authors: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing, 100083 China.
authors: Feng
authors: F
authors: Peng
authors: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, 510640 China ; Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing, 100083 China.
authors: Runcang
authors: R
authors: Sun
keywords: Corncob; Depolymerization of hemicelluloses; Furfural; Heterogeneous catalysis; Microwave-assisted hydrothermal pretreatment; Two-step process