本文選題：SAPO-18分子篩　切入點：1-丁烯　出處：《東北石油大學》2017年碩士論文

【摘要】：丙烯作為原材料在石油化工企業(yè)中有著不可或缺的地位。隨著工業(yè)的迅猛發(fā)展,中國已經步入亞洲乃至全球丙烯生產及消費大國的行列。但在丙烯的供需上還存在巨大缺口,所以利用烯烴催化裂化產生高經濟價值的丙烯工藝受到廣泛關注�，F(xiàn)今石化行業(yè)中所應用的裂解烯烴催化劑ZSM-5具備良好的裂解活性,但多環(huán)芳烴的選擇性較高,沒有達到令人滿意的丙烯選擇性。因此,研究具備高丙烯選擇性的催化劑有著更為重要的意義。首先,本文合成了不同Si含量的SAPO-18分子篩,并且利用了XRD、SEM、NH3-TPD技術手段進行了分子篩表征分析。通過微型固定床反應器評價了代表不同結構的H-ZSM-5(MFI)、H-Beta(*BEA)、SAPO-18(AEI)系列分子篩催化1-丁烯裂解性能。實驗結果表明:分子篩的結構和酸性對反應結果都有明顯影響,增加分子篩酸量會提高1-丁烯的轉化率,但酸量過高會引發(fā)氫轉移、芳構化等副反應導致丙烯選擇性降低;分子篩孔口大小、孔道結構決定了可以獲得的最高丙烯選擇性。本文還進行了SAPO-18分子篩催化1-己烯、1-辛烯裂解評價實驗,并比較1-丁烯、1-己烯與1-辛烯裂解產物分布。實驗結果發(fā)現(xiàn):烯烴碳鏈的長度會影響SAPO-18分子篩催化烯烴裂解性能。1-丁烯與1-己烯容易擴散到分子篩籠內發(fā)生裂解反應;1-辛烯在SAPO-18分子篩的八元環(huán)孔口發(fā)生了更強烈地吸附,導致1-辛烯擴散進入籠內進一步裂解速率明顯下降。通過TG手段對裂解反應后的分子篩積碳進行了分析,實驗結果表明:裂解反應過程中烯烴采用的裂解方式不同,分子篩的積碳量有著明顯的差異。SAPO-18分子篩催化1-己烯、1-辛烯采用單分子裂解方式生成易擴散的小分子,縮減了積碳前驅體產生的機率,因此積碳量相對少。而SAPO-18分子篩催化1-丁烯采用雙分子二聚裂解方式,盡管二聚裂解方式提高了丙烯收率,但二聚裂解過程中會產生大分子芳烴物質,其無法從分子篩籠內擴散加快了積碳的生成。最后,考察了不同反應溫度和反應空速對SAPO-18分子篩催化1-丁烯、1-己烯與1-辛烯裂解反應的影響,實驗結果表明:在反應溫度為500℃,1-丁烯空速為3.5h-1時,SAPO-18分子篩在1-丁烯催化裂解反應表現(xiàn)出較好的催化性能。在反應溫度為500℃,催化劑填料為1g,進料氣速為20ml/min,1-己烯與混合氣配比為2.5:1;1-辛烯與混合氣配比為1:1時,1-己烯、1-辛烯在SAPO-18分子篩上催化裂解反應表現(xiàn)出較好的催化結果。
[Abstract]:Propylene, as a raw material, plays an indispensable role in petrochemical enterprises. With the rapid development of industry, China has stepped into the ranks of Asian and even global propene producing and consuming countries. However, there is still a huge gap in the supply and demand of propylene. Therefore, the process of producing high economic value propylene by olefin catalytic cracking has attracted wide attention. Nowadays, the olefin cracking catalyst ZSM-5 used in petrochemical industry has good cracking activity, but the selectivity of polycyclic aromatic hydrocarbons (PAHs) is high. Therefore, it is more important to study catalysts with high propylene selectivity. Firstly, SAPO-18 molecular sieves with different Si content have been synthesized. The molecular sieve was characterized and analyzed by XRDX SEMN NH3-TPD. The catalytic properties of H-ZSM-5 MFI (H-BetaEI) series, representing different structures, for 1-butene cracking were evaluated by means of micro-fixed-bed reactor. The experimental results showed that the structure of the molecular sieve was characterized by SAPO-18AEI. And acidity have a significant effect on the results of the reaction, The conversion of 1-butene can be increased by increasing the acid content of molecular sieve, but the hydrogen transfer will be initiated when the acid content is too high, the selectivity of propene will be decreased due to the side reactions such as aromatization, and the pore size of molecular sieve will be decreased. The highest selectivity of propylene was determined by pore structure. The evaluation experiment of 1-hexene 1-octene cracking catalyzed by SAPO-18 molecular sieve was also carried out. The distribution of 1-butene 1-hexene and 1-octene pyrolysis products were compared. The results showed that the length of olefins carbon chain affected the cracking performance of olefin catalyzed by SAPO-18 molecular sieve .1-butene and 1-hexene easily diffused into the molecular sieve cage to produce cracking. The reaction of 1-octene adsorbed more strongly at the octa-ring pore of SAPO-18 molecular sieve. As a result, the further cracking rate of 1-octene diffusion into the cage was significantly decreased. The carbon deposition of molecular sieve after pyrolysis was analyzed by TG. The experimental results showed that the cracking modes of olefin were different during the cracking reaction. The carbon content of molecular sieve has obvious difference. SAPO-18 molecular sieve catalyzes 1-hexene 1-octene to form easily diffusing small molecule by single molecule cracking, which reduces the probability of producing carbon precursor. Therefore, the amount of carbon deposition is relatively small, while SAPO-18 molecular sieve catalyzes 1-butene by bimolecular dimerization, although dimeric cracking improves the yield of propylene, macromolecular aromatics are produced in the process of dimeric cracking. The formation of carbon was accelerated by the impossibility of diffusion from the molecular sieve cage. Finally, the effects of reaction temperature and space velocity on the cracking of 1-butene 1-hexene and 1-octene catalyzed by SAPO-18 molecular sieve were investigated. The experimental results show that when the reaction temperature is 500 鈩，

本文編號：1659477