In this study, biodiesel was produced from waste vegetable oil using a heterogeneous base catalyst synthesized by impregnating potassium hydroxide(KOH) onto diatomite. Response surface methodology based on a central c...In this study, biodiesel was produced from waste vegetable oil using a heterogeneous base catalyst synthesized by impregnating potassium hydroxide(KOH) onto diatomite. Response surface methodology based on a central composite design was used to optimize four transesterification variables: temperature(30–120 °C), reaction time(2–6 h), methanol to oil mass ratio(10%–50%) and catalyst to oil mass ratio(2.1%–7.9%). A quadratic polynomial equation was obtained to correlate biodiesel yield to the transesterification variables. The diatomite–KOH catalyst was characterized using X-ray diffraction(XRD), Fourier transform infra-red spectroscopy(FTIR) and a scanning electron microscope(SEM) equipped with an energy dispersive X-ray detector(EDS). A maximum biodiesel yield of 90%(by mass) was obtained. The reaction conditions were as follows: methanol to oil mass ratio 30%, catalyst to oil mass ratio 5%, reaction time 4 h, and reaction temperature 75 °C. The XRD, FTIR and SEM(EDS) results confirm that the addition of KOH modifies the structure of diatomite. During impregnation and calcination of the diatomite catalyst the K2 O phase forms in the diatomite structural matrix and the active basicity of this compound facilitates the transesterification process. It is possible to recycle the diatomite–KOH catalyst up to three times. The crucial biodiesel properties from waste vegetable oil are within the American Standard Test Method specifications.展开更多
Biodiesel, which is a renewable and environmentally friendly fuel, has been studied widely to help remedy increasing environmental problems. One of the key processes of biodiesel production is oil extraction from oils...Biodiesel, which is a renewable and environmentally friendly fuel, has been studied widely to help remedy increasing environmental problems. One of the key processes of biodiesel production is oil extraction from oilseed materials. Switchable solvents can reversibly change from molecular to ionic solvents under atmospheric CO_2,and can be used for oil extraction. N, N-dimethylcyclohexylamine(DMCHA), a switchable solvent, was used to extract oil from Jatropha curcas L. oil seeds to produce biodiesel. The appropriate extraction conditions were:1:2 ratio of seed mass to DMCHA volume, 0.3–1 mm particle size, 200 r·min-1agitation speed, 60 min extraction time, and 30 °C extraction temperature. The extraction ratio was about 83%. This solvent extracted the oil more efficiently than hexane, and is much less volatile. By bubbling CO_2 under 1 atm and 25 °C for 5 h, the oil was separated, and DMCHA was recovered after releasing CO_2 by bubbling N_2 under 1 atm and 60 °C for 2 h. The residual solvent content in oil was about 1.7%. Selectivity of DMCHA was evaluated by detecting the protein and sugar content in oil. Using the oil with residual solvent to conduct transesterification process, the oil conversion ratio was approximately 99.5%.展开更多
基金support by the centre of research excellence(Vaal University of Technology)grant no 2188-2892 to fund this project is gratefully acknowledged
文摘In this study, biodiesel was produced from waste vegetable oil using a heterogeneous base catalyst synthesized by impregnating potassium hydroxide(KOH) onto diatomite. Response surface methodology based on a central composite design was used to optimize four transesterification variables: temperature(30–120 °C), reaction time(2–6 h), methanol to oil mass ratio(10%–50%) and catalyst to oil mass ratio(2.1%–7.9%). A quadratic polynomial equation was obtained to correlate biodiesel yield to the transesterification variables. The diatomite–KOH catalyst was characterized using X-ray diffraction(XRD), Fourier transform infra-red spectroscopy(FTIR) and a scanning electron microscope(SEM) equipped with an energy dispersive X-ray detector(EDS). A maximum biodiesel yield of 90%(by mass) was obtained. The reaction conditions were as follows: methanol to oil mass ratio 30%, catalyst to oil mass ratio 5%, reaction time 4 h, and reaction temperature 75 °C. The XRD, FTIR and SEM(EDS) results confirm that the addition of KOH modifies the structure of diatomite. During impregnation and calcination of the diatomite catalyst the K2 O phase forms in the diatomite structural matrix and the active basicity of this compound facilitates the transesterification process. It is possible to recycle the diatomite–KOH catalyst up to three times. The crucial biodiesel properties from waste vegetable oil are within the American Standard Test Method specifications.
基金Supported by Doctoral Fund of Ministry of Education of China(20130181130006)the National Natural Science Foundation of China(No.21476150)
文摘Biodiesel, which is a renewable and environmentally friendly fuel, has been studied widely to help remedy increasing environmental problems. One of the key processes of biodiesel production is oil extraction from oilseed materials. Switchable solvents can reversibly change from molecular to ionic solvents under atmospheric CO_2,and can be used for oil extraction. N, N-dimethylcyclohexylamine(DMCHA), a switchable solvent, was used to extract oil from Jatropha curcas L. oil seeds to produce biodiesel. The appropriate extraction conditions were:1:2 ratio of seed mass to DMCHA volume, 0.3–1 mm particle size, 200 r·min-1agitation speed, 60 min extraction time, and 30 °C extraction temperature. The extraction ratio was about 83%. This solvent extracted the oil more efficiently than hexane, and is much less volatile. By bubbling CO_2 under 1 atm and 25 °C for 5 h, the oil was separated, and DMCHA was recovered after releasing CO_2 by bubbling N_2 under 1 atm and 60 °C for 2 h. The residual solvent content in oil was about 1.7%. Selectivity of DMCHA was evaluated by detecting the protein and sugar content in oil. Using the oil with residual solvent to conduct transesterification process, the oil conversion ratio was approximately 99.5%.
基金Project supported by the Natural Science Foundation Project of CQ CSTC （No. 2010BB5064）, Sharing Fund of Chongqing University＇s Large-Scale Equipment （No. 2010063040）, Scientific Research Fund of Chongqing University for the Introduction of Talent （No. CDJRC 10220004）, Innovative Talent Training Project of Chongqing University, the Third Stage of ＂211 Project＂ （No. S-09103） and Chongqing Municipal Education Commission Project （No. KJ-091201）.
