Huiwen Li

Promotional effect of transition metal doping on the properties of KF/CaO catalyst for biodiesel synthesis

ABSTRACT A series of heterogeneous KF/CaO catalysts modified with transition metals (lanthanum, cerium, and zirconium) were prepared via wet impregnation method and applied to the trsansesterification process of waste cooking oil (WCO) as feedstock with methanol to biodiesel production. The structure, performance of the solid catalysts was characterized by X-ray diffraction (XRD), temperature programmed desorption of CO2 (CO2-TPD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The effect of methanol/oil molar ratio, 1reaction time, reaction temperature, catalyst amount, and stability was investigated. The results showed that 10 wt% of lanthanum, cerium, and zirconium improved the catalytic activity of KF/CaO catalyst. The maximum catalytic activity using the lanthanum doping of 10wt% on KF/CaO catalyst was reached 98.7% under the optimal reaction condition of methanol/oil molar ratio of 12:1, reaction for 1 h at reaction temperature of 65°C, and 4% (wt/wt oil) catalyst amount. In addition, the FAME yield of KF/CaO/La catalyst remained higher than 95% after 10 cycles. The promotional effect of lanthanum doping could be attributed to the enhancement of the basicity strength of KF/CaO catalyst and block the leach of Ca2+ in the transesterification reaction.

Synthesis of Glycerol Carbonate from Glycerol and Dimethyl Carbonate Using Ionic Liquid Catalysts

Acidic, basic and neutral ionic liquids (ILs) were prepared by two-step method. Their IR and NMR spectra showed that their structures were in accordance with their theoretical structure. Then these ILs were used as catalysts in the Glycerol carbonate (GC) of glycerol with dimethyl carbonate (DMC). The results show that basic ILs have high catalytic activity compared with acidic or neutral ILs and inorganic basic catalysts in the reaction. Under the suitable conditions using [Bmin]lm as a catalyst led to the yield of GC reached 94%, glycerol conversion reached 96%, GC selectivity reached 97% at molar ratio of DMC to glycerol at 3: 1, mass fraction of ionic liquid 12% (omega), reaction temperature 80 degrees C and reaction time 70 min. The ionic liquid was stable, and its activity did not decrease after using for 8 times (i. e., 85% glycerol conversion and near 90% GC selectivity). The results showed that the basic ionic liquid is more ideal green catalyst in esterification reaction.