| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 105 === This study took advantages of using self-manufactured catalysts which were made by adding Mo2C on the surface of γ-Al2O3 particles to conduct the catalytic hydrocracking of tung oil. Tung oil was converted to bio-fuel oil (BFO) as an alternative of aviation fuels or fuel oils. The batch system was designed for the catalytic hydrocracking with a removal packed bed filled with catalyst at a present temperature. By varying experimental conditions, this study was performed to investigate the effects of reaction temperature (T), hydrogen pressure (PH2), holding time (t), types of catalysts, amount of catalyst added (MC), volume of raw tung oil (VLO), and two-stage reaction on the system performances. These include yields of the produced BFOs (YBFO) and their characteristics, such as acid value (AV), iodine value (IV), density (ρLO), heating value (HV), distribution of carbon numbers, and content of (MC1C9), C1~C9 elemental composition. In the same time, products of solid and gas were also analyzed for the related characteristics.
The study consists of four parts. The first part was the development of method for preparation of Mo2C based catalysts. The second part was catalytic cracking of tung oil with different reaction temperatures and catalysts (γ-Al2O3 and Mo2C/γ-Al2O3). For the third part, direct cracking of tung oil under different nitrogen pressures was conducted. The forth part was catalytic hydrocracking of raw tung oil with different hydrogen pressures, holding times, volumes of raw tung oil, amounts of catalyst added, and types of processes with one or two stages of reactions.
The results showed that tung oil is mainly composed of C16 ~ C22 unsaturated fatty acids. In the catalytic cracking with Mo2C/γ-Al2O3, it achieved MC1C9 = 73 wt%, HV = 47 MJ/kg, and YBFO = 65 vol% at 623 K, 100 psig Ar, 20 min, and MC = 1 wt%. For the direct cracking, the higher the nitrogen pressure, the better the effect of cracking giving higher MC1C9 and HV. At 623 K, 100 psig N2, and 20 min, MC1C9 in BFO was 66 wt% and HV and YBFO of BFO were 58 MJ/kg and 78 vol%, respectively. In the catalytic hydrocracking test, an increasing of catalyst reduced the oxygen content while enhanced the heating value of BFO. At 623 K, 100 psig H2, 40 min, and MC = 5wt%, the oxygen content was 1.5wt%, while MC1C9 = 82 wt%, HV = 38 MJ / kg, and YBFO = 53 vol%. In the stage-wise catalytic hydrocracking , HV and YBFO of BFO of the two-stage reaction were moderate while with high MC1C9. If applying one stage reaction at 623 K, 100 psig H2, 40 min, and MC = 1 wt%, values of MC1C9, HV, and YBFO of BFO were 76 wt%, 34 MJ/kg, and 65 vol%, respectively. For the two-stage reaction, at 623 K, 100 psig N2 (20 min, first stage), 100 psig H2 (40 min, second stage), and MC = 1 wt%, the values of MC1C9, HV, and YBFO were 83 wt%, 30 MJ/kg, and 52 vol%, respectively. For the case with highest overall performance index (PIt) of 0.80 at 623 K, 100 psig H2, 20 min, and MC = 1 wt%, the BFO had MC1C9 = 73 wt%, HV = 54 MJ/kg, and YBFO = 67 vol% with the AV and HV satisfying with the standards of aviation fuel oil. Further, from the results of species analysis, it was found that there were C7 ~ C17 straight chain alkanes in the products. Thus, it is feasible to produce the available BFO via the catalytic hydrocracking used in this study. Therefore, by fractionating the BFO, it can be blended in aviation fuel or gasoline or used directly as fuel oil.
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