【摘要】：隨著石油資源的日漸枯竭,以它為原料的汽油、柴油等液態(tài)燃料能否被持續(xù)和穩(wěn)定地供應成了消費市場的重大隱憂,以煤、天然氣、生物質(zhì)轉(zhuǎn)化制取液態(tài)燃料技術受到越來越多的關注,而費托合成(F-T)是實現(xiàn)這種轉(zhuǎn)化的重要途徑之一。鈷(Co)基催化劑具有較高的CO加氫活性和F-T反應鏈增長能力,高轉(zhuǎn)化率下具有更高的生產(chǎn)能力,適用于氫碳比更高的反應體系,反應過程較為穩(wěn)定不易積碳和中毒,產(chǎn)物中含氧化合物少,對水氣變換反應不敏感、活性低。因此Co基催化劑被視為低溫F-T反應制取長鏈烴的首要選擇,具有良好的應用前景。本文重點考察了介孔碳載體的制備方法,介孔碳載體的孔道對于Co基催化劑的F-T反應活性以及產(chǎn)物選擇性的影響、分子篩SBA-15載體修飾改性對于Co基催化劑F-T合成反應活性以及產(chǎn)物選擇性的影響。不同催化劑對于汽油段(C5-C10)、柴油段(C10-C20)產(chǎn)物選擇性有著較大的差異。通過前期的制備工作以及X射線衍射(XRD)、N2物理吸附-脫附、程序升溫還原(TPR)、掃描電鏡(SEM)等表征手段,得到了以下結果:(1)以SBA-15為模板,蔗糖為碳源,通過改變SBA-15制備過程中的晶化、老化溫度,制備出了一系列孔徑、比表面積漸變的介孔碳材料,并以其為Co基催化劑的載體,研究了其孔徑、比表面積大小對Co基催化劑F-T反應性能的影響。所制備的碳材料孔徑介于3.42-5.14nm、比表面積介于410.50-1141.00m2·g-1范圍內(nèi)。催化劑F-T反應性能測試表明,載體孔徑、比表面積對催化劑F-T反應活性有著重要的影響;孔徑為5.14nm、比表面積為1003.68 m2·g-1的介孔碳載體所制備出的催化劑顯示出了最高的F-T反應活性以及C5+產(chǎn)物選擇性,其中C10-C20的選擇性達到了56.19%。(2)通過往分子篩SBA-15孔道中填充不同質(zhì)量比的蔗糖、并以碳化,探討經(jīng)過不同質(zhì)量蔗糖修飾的SBA-15載體對于Co基催化劑F-T反應活性以及產(chǎn)物選擇性的影響。不同質(zhì)量比的蔗糖的加入使得Co基催化劑的反應活性有了一定幅度的下降,但F-T反應產(chǎn)物分布發(fā)生了明顯的前移。在催化劑Co/SBA-15C中,隨著蔗糖加入量的增加,催化劑的CO轉(zhuǎn)化率以及產(chǎn)物的C5+選擇性均呈現(xiàn)出先減小后增大再減小的趨勢,Co/SBA-15C3有著最高的C5+選擇性,其中C5-C10選擇性高達55.85%。(3)以工業(yè)通用級聚苯乙烯(PS,PG-22)為成膜材料,采用呼吸圖案法制備了多孔膜,并利用掃描電鏡(SEM)對多孔膜的形貌進行了觀察,得出了制備有序多孔膜的適宜條件為:在環(huán)境溫度為25℃和用甲苯為溶劑時,聚合物濃度為25mg/mL,用量為0.8mL,環(huán)境濕度85%(相對濕度),并保持靜態(tài)氣氛。采用PS溶液多次涂覆方法可以增加多孔膜厚度。在此基礎上利用PS有序多孔膜對SBA-15進行了修飾,發(fā)現(xiàn)修飾后的催化劑由于孔道的堵塞以及還原度的降低導致了催化劑的F-T反應活性較低,產(chǎn)物中CO、CH4選擇性較高,C5+選擇性降低。
[Abstract]:With the gradual depletion of petroleum resources, whether the liquid fuels such as gasoline, diesel and other liquid fuels, such as gasoline and diesel, which are used as raw materials, can be continuously and stably supplied has become a major hidden concern in the consumer market. With coal and natural gas, More and more attention has been paid to the technology of biomass conversion to produce liquid fuel, and Fischer synthesis (F-T) is one of the important ways to achieve this conversion. Cobalt (Co) based catalyst has high CO hydrogenation activity and F-T reaction chain growth ability, and has higher production capacity under high conversion rate. It is suitable for the reaction system with higher hydrogen-carbon ratio, and the reaction process is stable and not easy to deposit carbon and poisoning. The product contains less oxygen compounds, is insensitive to water gas shift reaction, and has low activity. Therefore, Co catalyst is regarded as the first choice of low temperature F-T reaction to produce long chain hydrocarbon, which has a good application prospect. The preparation method of mesoporous carbon carrier and the influence of the pore channel of mesoporous carbon carrier on the F-T reaction activity and product selectivity of Co based catalyst were investigated. Effects of modification of molecular sieve SBA-15 support on F-T synthesis activity and product selectivity of Co-based catalyst. The selectivity of different catalysts for gasoline stage (C5-C10) and diesel oil stage (C10-C20) was different. The results were as follows: (1) SBA-15 was used as template, sucrose as carbon source, and (XRD), N2 was physically adsorbed and desorbed by X-ray diffraction (XRD), and (TPR), scanning electron microscopy (SEM) was used to reduce temperature programmed reduction, the results were as follows: (1) using SBA-15 as template, sucrose was used as carbon source. A series of mesoporous carbon materials with varying pore size and specific surface area were prepared by changing the crystallization and aging temperature during the preparation of SBA-15. The pore size of mesoporous carbon materials was studied by using it as the carrier of Co based catalyst. Effect of specific Surface area on the performance of Co based Catalysts for F-T reaction. The pore size of the carbon materials was 3.42-5.14 nm and the specific surface area was in the range of 410.50-1141.00m2 g ~ (-1). The performance of the catalyst F-T reaction showed that the pore size and specific surface area of the catalyst had important effects on the activity of the catalyst F-T reaction. The catalyst prepared by the mesoporous carbon carrier with a pore size of 5.14 nm and a specific surface area of 1003.68 m2 g ~ (-1) showed the highest F-T reaction activity and the selectivity of C _ 5 products. The selectivity of C10-C20 reached 56.19. (2) by filling different mass ratios of sucrose in the pore of molecular sieve SBA-15 and carbonizing, The effects of sucrose modified SBA-15 support on the F-T reaction activity and product selectivity of Co based catalyst were investigated. The addition of sucrose with different mass ratio decreased the activity of Co catalyst to a certain extent, but the product distribution of F-T catalyst moved forward obviously. In the catalyst Co/SBA-15C, with the increase of sucrose content, the conversion of CO and the C5 selectivity of the product showed a tendency of decreasing first, then increasing, then decreasing. Co/SBA-15C3 had the highest C5 selectivity. The selectivity of C5-C10 is as high as 55.85. (3) porous membranes were prepared by respiratory pattern method using industrial polystyrene (PS,PG-22) as film forming material. The morphology of the porous membrane was observed by scanning electron microscope (SEM). The optimum conditions for the preparation of ordered porous membrane were obtained as follows: the concentration of polymer was 25 mg / mL and the amount of polymer was 0.8 mL when the ambient temperature was 25 鈩，

本文編號：2321204