Preparation Of Magnetic Catalysts And Their Application In The Preparation Of Biodiesel

Increasing demands in energy and industrialization, as well as environmental concerns caused by the use of fossil fuels, have encouraged researchers to develop alternative fuels and renewable sources of energy. Biodiesel, derived from renewable biological sources, such as vegetable oils and animal fats, is a popular and environmentfriendly alternative to fossil fuels because of its renewability, emission, security, and biodegradability. Non-edible oils should be used to produce biodiesel based on the basic national conditions, which has a big population and little farmland. Furthermore, among the methods for the production of biodiesel, magnetic solid acid or base catalysts not only have excellent catalytic activity, and can be easily separated and reused under magnetic field. On the basis of these, on the one hand to carry out research work related to screening and fuel properties testing and other aspects of research on non-edible oils, on the other hand, we prepared the magnetic solid acid and base catalysts to produce biodiesel and got the following results:?1? Firstly, we have screened out two kinds of non-food oil sources, including Firmiana platanifolia and Koelreuteria integrifoliola. In the research work, we measured the fatty acid composition and other physical and chemical properties of the two oils first of all. Based on the results, the seed oil content of Koelreuteria integrifoliola was up to 38.77%, and the seed kernel oil content of Firmiana platanifolia was 36.47%. Additionally, the average acid value of F. platanifolia L.f. oil was 1.19 mg KOH g-1, indicated that the obtained oil with such a low acid value was therefore enabled its direct alkali transesterification for biodiesel production without acid pretreatment. And then according to the results based on the fuel properties derived from the two oils, they both fulfilled ASTM D6751 and EN 14214 biodiesel specifications. In particular, their cetane number and oxidation stability were higher than the standards. Unfortunately, the two kinds of biodiesel have a poor performance on cold filter plugging point On the whole, the results indicated that F. platanifolia L.f. is a potential species to be used as a biodiesel feedstock in China.?2? The magnetic core-shell support Fe₃O₄@SiO₂ was prepared through a sol-gel method, and further sulfonated with chlorosulfonic acid to obtain a magnetic solid acid catalyst Fe₃O₄@SiO₂-SO₃ H. The catalyst was characterized by XRD, TEM, FT-IR techniques and so on, and its catalytic activity was explored through production of biodiesel by esterification of oleic acid with methanol. According to the orthogonal experiment, the suitable conditions for esterification of oleic acid with methanol were obtained: reaction time 5 h, reaction temperature 120 oC, molar ratio of methanol to oleic acid 20:1, and catalyst dosage 4 wt %. Under the conditions, the conversion of oleic acid could reach 98.3%. Furthermore, the catalyst has a good reusability?7th conversion rate of 88.8%?, indicating that the catalyst has good stability and reusability.?3? After the acid value of feedstocks was reduced through esterification rection, researchers often choose a more effective reaction through a solid base catalyst to produce biodiesel. The major work of this part was to combine basic IL with magnetic core-shell support Fe₃O₄@SiO₂ to prepare a magnetic solid base catalyst. Such as FTIR, elemental analysis and other technologies was carried out to characterize the catalyst. By using the refined Koelreuteria integrifoliola oil?AV=1.2 mg KOH/g?, single factor optimization method was adopted here to investigate the optimal reaction conditions through transesterification. On the basis of the experimental data, the suitable conditions for transesterification were obtained: reaction time 8 h, reaction temperature 160 oC, molar ratio of methanol to oleic acid 30:1, and catalyst dosage 8 wt %. Under the conditions, the highest FAME content could reach 89.1%. Furthermore, the reusability of the catalyst was also investigated, under optimum conditions, the catalyst can be reused 4th ester content reduced to 62.2%, indicating that the catalyst has a certain degree of reusability.?4? This part of the work was to prepare the acidic IL functionalized Fe₃O₄@SiO₂ core-shell magnetic carrier to obtain a magnetic solid acid catalyst. In this way, high acid value oil which was required by the acid-base coupling method through a two-step process could be simplified over an "one-pot" simultaneously catalyze esterification and transesterification reaction to produce biodiesel. Acidic IL functionalized Fe₃O₄@SiO₂ magnetic core-shell support as a magnetic solid acid catalyst was prepared to catalyze the “one-pot” reaction for the production of biodiesel. By using the crude Koelreuteria integrifoliola oil?AV=4.66 mg KOH/g?, orthogonal experiment was adopted here to investigate the optimal reaction conditions. On the basis of the experimental data, the suitable conditions were obtained: reaction time 10 h, reaction temperature 160 oC, molar ratio of methanol to oleic acid 40:1, and catalyst dosage 10 wt %. Under the conditions, the highest FAME content could reach 95.3%. And the hot filtration experiment was adopted here to confirm this catalyst was a heterogeneous catalyst. Furthermore, the reusability of the catalyst was also investigated, under optimum conditions, the catalyst can be reused 5th ester content reduced to 78.7%, indicating that the catalyst has a certain degree of reusability.