以碳化鉬觸媒進行批次式桐油氫化裂解產製生質油品之研究

Abstract

本研究使用碳化鉬觸媒，批覆在活性氧化鋁顆粒之表面，進行桐油氫化裂解改質轉製成可用於航空油或汽油的生質油品。利用可卸式觸媒床填充自行合成的觸媒於高溫下進行批次式反應探討溫度(T)、氫氣壓力(PH2)、持溫時間(t)、不同觸媒、觸媒添加量(MC)、桐油添加量及二階段(觸媒裂解及氫化觸媒裂解)反應對於桐油改質後之生質油品的產率(YBFO)與特性(酸價、碘價、密度、熱值、碳數分布及元素組成等)之影響，並找出最適反應條件。以製備可用於航空燃料油或是汽油的生質油品。同時對反應過程產生的副產物(固體、氣體)，作相關分析(產率、熱值、元素分析等)。 研究可以概分為四部分。第一部分為Mo2C觸媒製備技術之開發。第二部分為桐油觸媒裂解改質試驗，利用不同溫度條件與不同觸媒(Mo2C/γ-Al2O3及γ-Al2O3)進行試驗。第三部分為桐油直接裂解改質試驗，利用不同氮氣壓力進行試驗。第四部分為桐油觸媒氫化裂解，利用不同氫氣壓力、桐油使用量、持溫時間、觸媒添加量及二階段反應條件進行試驗。 研究結果顯示，桐油主要組成碳數為C16~C22之不飽和脂肪酸。使用Mo2C/γ-Al2O3為觸媒進行觸媒裂解時，於623 K, 100 psig Ar, 20 min,在觸媒添加量MC = 1 wt%時，生質油產物BFO中時之C1~C9的含量(MC1C9)為73 wt%，碳數降低的效果相當顯著，其熱值約為47 MJ/kg, YBFO為65 vol%。在直接裂解試驗中，氮氣壓力越高，裂解效果越佳，其MC1C9及熱值越高，於623 K,100 psig N2, 20 min時，MC1C9為66 wt%，熱值為58 MJ/kg, YBFO = 78 vol%。在觸媒氫化裂解試驗中，觸媒添加量增加時，氧元素含量降低及熱值升高。於623 K, 100 psig H2, 40 min，在MC = 5 wt%時，氧含量為1.5 wt%，MC1C9 = 82 wt%，熱值為38 MJ/kg, YBFO = 53 vol%。在階段反應觸媒氫化裂解試驗中，二階段反應的熱值及產率皆表現不佳，但MC1C9高。若是在一階段反應於623 K, 100 psig H2, 40 min, MC = 1 wt%時，MC1C9 = 76 wt%，熱值為34 MJ/kg，YBFO為65 vol%。二階段反應於623 K, 100 psig N2, (20 min), 100 psig H2, (40 min), MC = 1 wt%時，MC1C9 = 83 wt%，熱值為30 MJ/kg，YBFO為52 vol%，在最適條件時(623 K, 100 psig H2, 20 min, MC = 1 wt%，最高總效能指數 (Overall performance index) PIt = 0.80 )，BFO之MC1C9 = 73 wt%, HV= 54 MJ/kg, YBFO = 67 vol%，其酸價及熱值皆符合航空燃油之燃料油品標準規範。從物種分析結果，顯示產物中有C7~C17的直鏈狀烷類，可見以本研究所提之觸媒氫化裂解方法生產可用的生質油品是可行的。因此，若將產出的生質油品加以分餾收集，將可以與航空燃料或汽油中摻配使用或直接使用。

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.