Preparation Of Solid Strong Base Catalyst And Application In Synthesis Of Biodiesel

With the characteristic of clean and renewable, properties of biodiesel is similar with fossil fuel for the ideal substitute fuel. Nowadays, the most production methods of biodiesel are homogeneous catalysis productions, but there are many disadvantages of homogeneous catalysis, such as high-erosion to equipment, difficult to recycle of catalyst, difficult to separate of products and clean with much water (need much water to clean), heterogeneous catalysis can resolve these problems, but it’s high cost to produce the heterogeneous catalyst, for expensive raw materials and complex preparation process. In this paper, a method was used to prepare solid catalyst which used wet process to support calcium hydroxide and sodium hydroxide on the supporter of activated clay respectively. This method has competitive advantages, inexpensive raw materials-activated clay, simple wet process with control product properties easily. Activated clay solid base biodiesel catalyst is a product with high market competitiveness.In the paper, the process of preparation of activated clay solid base was researched by orthogonal test and single factor, the results showed the optimum condition:When loading0.66mmol Ca(OH)2·g-1clay, adding17mmol NaOH·g-1clay, fourfold water at the temperatures in the range of80℃for3.5h of feeding time. At these conditions, the supported sodium hydroxide on the activated clay prepared was3.4mmol NaOH·g-1. The most influence factors were the added quantity of sodium hydroxide, calcium hydroxide amount on the alkaline clay and supported temperatures. The alkaline clay and activated clay catalyst were characterized by DSC and XRD, results showed that the structure and thermal stability were the same with activated clay.The paper used activated clay catalyst to catalyze the transesterification of soybean oil and methanol. The results showed the optimum condition of preparation was as following:3.0wt%of adding amounts of catalyst,12:1of molar ratio between methanol and oil,30℃(1h)-40℃(1h)-50℃(2h)-60℃(3h) of the optimum reaction temperature and time,200-400mesh of granularity of catalyst. At these conditions, catalyzing soybean oil and methanol, the methyl ester content of product reached96.7%. Activated clay catalyst which was used in different Catalytic conditions were characterized by DSC, results showed that the temperature-gradient method was better than one step way, the former the structure of catalyst was remained, but the later the structure of catalyst was destroyed into pieces. The temperature-gradient method not only protect the structure and properties of the catalyst but also it’s a energy saving way.