A study on the catalytic performance of carbide slag in transesterification and the calculation of kinetic parameters

The catalytic performance of carbide slag in transesterification is investigated and the reaction kinetic parameters are calculated. After being activated at 650°C, calcium compounds of carbonate and hydroxide in the carbide slag are mainly transformed into calcium oxide. The activated carbide slag utilized as the transesterification catalyst is characterized by X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), nitrogen adsorption-desorption and the Hammett indicator method. Compared with the carbide slag activated at 700 and 800°C, the largest surface area of 22.63 m2 g−1, the smallest particle size of 265.12 nm and the highest catalytic efficiency of the carbide slag activated at 650°C guarantee its capacity in catalyzing transesterification. Then, the influences of activated temperature (T a), molar ratio of methanol to oil (γ), catalyst added amount (ζ), reaction temperature (T r) and reaction time (τ) on the catalytic performance are investigated. Under the optimal transesterification condition of T a=650°C, γ=15, ζ=3%, T r=60°C and τ=110 min, the catalytic efficiency of 92.98% can be achieved. Finally, the kinetic parameters of transesterification catalyzed by the activated carbide slag are calculated, where activation energy (E) is 68.45 kJ mol−1 and pre-exponential factor (k 0) is 1.75×109 min−1. The activated carbide slag shows better reused property than calcium hydroxide.