Catalytic Conversion Of Cellulose And Fructose To Lactic Acid

In order to reduce the dependence on fossil fuels and restrict the emissions of carbon dioxide, more and more research focuses on the catalytic conversion of biomass resources into high-quality biofuels and chemicals. Cellulose and fructose are important components of biomass, and have become potential substitute for non-renewable energy resources.Lactic acid is one of multifunctional platform chemicals,and is widely used in food, pharmaceutical, medical and cosmetic industry. So far, lactic acid is mainly derived from enzymatic hydrolysis, but there are some defects for themethod.The reaction rate of enzymatic hydrolysis is slow, the space-time yield is also low, the energy consumption is high, and the raw material purification is difficult. Therefore, the development of environmentally friendly methods for the chemical transformation of biomass resources has become the main goal of people's efforts to explore.Biomass cellulose and fructose were used as raw materials in this work to explore the catalytic activity of two different types of catalysts. The catalytic performance of Er3O3/Al₂O₃ catalysts and La-HPMo catalystsin the conversion of biomass materialsto lactic acid were investigated, respectively. The obtained results are as follows:A series of alumina-supported Er₂O₃ catalysts were prepared by impregnation method,the catalysts showed good catalytic activity in the preparation of lactic acid from cellulose.Theinfluences of reaction time, reaction temperature and cellulose amount were investigated.Lactic acid yields as high as 45.8% were obtained when reacting 0.2 g cellulose,0.05 g catalyst and 30 mL water at 240? under 2 MPa N2 for 3 h using Er₂O₃/Al₂O₃-4 as the catalyst. Moreover, this catalyst could be reused three times without gradual loss of activity. The catalytic materials synthesized in this work were characterized using a combination of X-ray fluorescence spectroscopy, N2 physical adsorption, powder X-ray diffraction, NH3 temperature-programmed desorption, as well as by analysis of FT-IR spectra following pyridine adsorption, the observed decreases in catalytic activity during recycling could be due to erbium ion leaching.Homogeneous La-HPMo catalysts were prepared by ion-exchange method, and the optimal reaction conditions were determined. Lactic acid yields as high as 61.2% were obtained when reacting 0.1 g fructose,0.07 g catalyst and 30 mL water at 170? under 2 MPa N2 for 60 min using La-HPM-3 as the catalyst. Moreover, this catalyst could be reused five times without loss of activity.The catalyst is suitable for the mass production of lactic acid from fructose.