Biodiesel Preparation Of Solid Catalyst And Its Application

Biodiesel as a green renewable energy, it has many advantages, such as better lubricity, biodegradation, at the same time, non-containing sulfur and aromatic-free. At present, biodiesel is produced through esterification or transesterification by homogeneous acid or homogeneous alkali. This technique has high reaction rate and conversion rate, but more waste liquid, difficulty in separation, complex process and so on.Using solid acid and alkali as the catalyst, it could be avoided the problem caused by homogeneous catalyst in reaction, and it has many advantages, such as mild reaction conditions, reusability of catalyst, automated continuous production, no corrosion of equipment and no pollution to environment. So, solid acid and alkali as catalyst to produce biodiesel was proposed in this paper.In this paper, solid acid and alkali catalysts were selected systematically and higher solid catalyst in biodiesel raw pretreatment or biodiesel production was obtained, such as SO42-/ZrO2, carbon-based solid acid and barium oxide. The foundation of biodiesel production catalyzed by solid catalyst was established through catalyst preparation and catalyst application in biodiesel production as the research object, and the condition of heterogeneous catalyst preparation was studied in this paper. The results are as follows:(1)The optimal conditions of SO42-/ZrO2solid catalyst preparation is that:Zirconium oxychloride solution and 28% ammonia were aged fot 3h under ultrasonic-assisted precipitation, placed for 24h in room temperature, washed with deionized water, and the precursor of zirconia was obtained by dried in the oven. The zirconia was immersed for 24g in 2mol-L-11H2SO4, calcined for 4h at 550℃. The conversion rate of oleic acid in traditional esterification was 92.83% by following conditions:SO42-/ZrO2 solid super acid 2.5%(W/W) as catalyst, the ratio of methanol to oleic acid 45% (W/W), reaction temperature 100℃and reaction time 4h, the conversion rate still maintained above 75% after repeatedly uses 5 times.Te conversion rate of oleic acid in gas esterification was 97.81% by following conditions: SO42-/ZrO2 solid super acid 4%(W/W) as catalyst, reaction temperature 100℃, reaction time 3.5h and vaporization temperature 85℃, the conversion rate still maintained above 36.56% after repeatedly uses 5 times. The results show that:gas esterification process is more suitable for reducing High-acid value of biodiesel feedstock, extend the life cycle of the catalyst after reaction by separation, washing and drying.(2)The optimal conditions of carbon-based solid acid preparation is that: starch and p-toluenesulfonic acid with the weight ratio of 25:6, it was solved with distilled water, carbonized for 10h at 200℃, cooled to room temperature, prepared into 60 mesh. The experimental results showed that the conversion rate of oleic acid was 80.21% in the traditional esterification by following conditions:the ratio of methanol to oleic acid 1:4(W/W), reaction time 6h, carbon-based solid acid 6.5%(W/W) as catalyst and at 100℃, the conversion rate still maintained above 70% after repeatedly uses 5 times. The results show that:the catalyst has good stability, but the activity was not high, which limit its application.(3)The optimal condition of barium peroxide solid base catalyst preparation is that:barium hydroxide was calcined for 4h at 200℃, cooled to room temperature, and placed in the dryer. The conversion rate of rapeseed oil was 96.82% by following conditions in the traditional transesterification:solid barium bioxide 0.9%(W/W) as catalyst, the ratio of methanol to rapeseed oil 30%(W/W), reaction temperature 70℃and reaction time 2.5h, the conversion rate still maintained above 83% after repeatedly uses 3 times; the conversion rate of rapeseed oil was 96.31% by following conditions in the gas-phase transesterification:vaporization temperature 90℃.solid barium bioxide 1.1%(W/W) as catalyst, reaction time 1.5h and reaction temperature 65℃, the conversion rate still maintained above 62% after repeatedly uses 5 times. The results show that: the catalyst mechanism of barium oxide is the same of KOH catalyst, extend the life cycle of the catalyst after reaction by separation, washing and drying.