| Faced to the more rigorous environment pollution caused by combustion of petrochemical diesel, the decreasing reserves of oil, the soaring international oil price and "Gulf Oil Spill" in Mexico, the human begin to realize the serious consequences caused by relying on oil resources too much. Therefore, it is very necessary to develop clean, efficient and renewable energy. Biodiesel is a series of long chain alkyl fatty acid esters, with a similar combustion performance of petrochemical diesel. It has a lot of characteristics such as the renewable of raw material, high oxygen content, burning thoroughly and less sulfur dioxide emission. Biodiesel is considered to be a promising substitute of petrochemical diesel.Our group has prepared DMC-palm-based biodiesel with new ester exchange reagent DMC and palm oil and succeeded in solving the low utilization ratio of raw material of methanol-biodiesel and production of excess glycerol. But DMC-palm-based biodiesel exists problems such as high cold filter point and pour point, poor oil low temperature fluidity, which greatly limits the the application of DMC palm-based biodiesel. This article is on the basis of previous work in my laboratory and improves low temperature fluidity through the choice of oil raw materials and ester exchange reagents for biodiesel. And the burning performance of biodiesel was investigated in the article.Firstly, prepared DMC-corn oil based-biodiesel through choosing corn oil with a higher degree of saturation as raw material. With the use of glycerol and DMC, by-product of biodiesel-glycerol carbonate was prepared and the synthesis on the structure was investigated on the basis of gas chromatography and nuclear magnetic resonance (NMR).The result proved glycerol carbonate to be the five-membered ring structure. In order to analysis the composition of DMC-corn oil-based biodiesel better, high temperature chromatographic column and gas chromatography were utilized, quantitative analysis methods of fatty acid methyl esters set up. Overall yield of fatty acid methyl esters was 90.7% when the reaction of DMC and corn oil happened at 9:1 ester oil ratio and 16.25% KOH at reflusing temperature at 9 h. The physical properties of the investigation on DMC-corn oil based biodiesel were carried on and found that cold filter point and pour point of the biodiesel were -9℃and-11℃, far below cold filter point and pour point of petroleum diesel which fits the requirements of fuels.Secondly, the long chain ester exchange reagent was chose to prepare for biodiesel and character of the composition of products were investigated. The biodiesel was preparated by palm oil reacting with DEC insteading of DMC and cold filter point and pour point of the biodiesel decrease from 11℃,9℃to -8℃,-9℃, which improved out the excellent low temperature fluidity of biodiesel. At the same time, the quantitative analysis method was established to analyse the main composition of DEC-palm based biodiesel by using internal seventeen acid methyl ester as the standard substance, high temperature chromatographic column and gas chromatography.This method was of high precision, high accuracy and good repeating rate and also easy to operate which met the requirements of quantitative research.Afer that,using the high degree of saturation of corn oil as the raw materials or the long chain ester exchange reagent could either improve the low temperature fluidity of biodiesel. Totally contrast, shorter cost and reaction time, lower cold filter point and pour point proved using the high degree of saturation of corn oil was better. So DMC-corn oil based biodiesel was chosen to inspect combustion performance of biodiesel.Finally,the physical properties of biodisel made from coin oil and DMC was investigated simultaneously.The study on engine performance, economy, emission characteristics and the solid particle emissions were conducted in a diesel engine fuelled with blends of coin oil methyl esters and diesel oil (the mixed ratio was 10:90, named B10). And the effects of the addition of DMC and GC in the blend fuel on engine fuel consumption were further investigated. The results showed that the density, flash point, kinematic viscosity, acid value, CFPP and pour point of coin biodiesel met the National Standards requrements. The contents of saturated methyl esters in coin biodiesel were low (about 15%),and its CFPP and pour point was -9℃,-11℃respectively, far below the 0# diesel's value (2℃,0℃respectively).So coin biodiesel had better cold flow properties than 0# diesel. The blend fuel can be directly applied in diesel engine and a slightly lower power performace and also a slightly fuel consumption increase was observed. CO, HC, aldehydes and SO2 emissions were slightly increased. And the small particle emission increases, meanwhile the big particle emission reduced. The article distrabution had a tendency to small particles.Total particles quality emussions and gatherated particles quality emussions were reduced, meanwhile nuclear state particles quality emussions were increased. The by-product GC and the ester exchange reagent have a little effect on combustion performances of the biodiesel fuel. |
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