氮化硼负载杂多酸催化氧化燃油深度脱硫研究

发布时间：2018-02-19 18:57

本文关键词： 氧化脱硫多相催化 POM/h-BN催化剂 h-BN H_2O_2　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,随着油品劣质化的加重,燃油的含硫量也随之增加。燃油燃烧产生的SOx会造成严重的环境污染,因此硫化物的脱除日益受到重视。燃油中的硫醇和硫醚可用简单的物理或化学方法脱除,而噻吩类硫很难用传统的加氢脱硫技术脱除。因此多种新型的脱硫方法应运而生,例如生物脱硫、吸附脱硫、萃取脱硫和氧化脱硫等。其中,氧化脱硫(ODS)因温和的反应条件和对芳香族硫化物的高活性已成为一种生产超低硫燃油的技术。ODS技术的关键是寻找一种高效稳定的催化剂。本论文设计合成了一系列氮化硼负载杂多酸催化剂,并将其用于燃油深度脱硫的研究。首先,以类石墨烯型六方氮化硼(h-BN)作载体,利用溶剂热法将磷钨酸(HPW)负载到少层的h-BN中,成功制备了HPW/h-BN多相催化剂。通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)等方法对催化剂进行表征,结果表明HPW被成功限域到h-BN的微孔中,且负载后h-BN的结构没有发生变化。在ODS体系中,HPW/h-BN对二苯并噻吩(DBT)和4,6-二甲基二苯并噻吩(4,6-DMDBT)表现出极好的催化性。HPW/h-BN对DBT的脱除率能达到100%,且循环使用6次后催化剂的脱硫效率没有明显的降低。机理分析显示,反应过程中DBT和H_2O_2同时被吸附到催化剂表面,然后[PW12O40]3-接受H_2O_2的活性氧形成过氧物种W(O)2,最后DBT被W(O)2氧化成DBTO2,实现硫化物的脱除。采用浸渍法将硅钨酸(HSiW)负载到h-BN中,成功制备了HSiW/h-BN多相催化剂。通过红外光谱(FT-IR)、XRD、SEM、TEM等表征方法分析催化剂的形貌和结构,结果表明多相化后HSiW在h-BN上高度分散,且HSiW中的W元素会发生价态变化。HSiW/h-BN对DBT和4,6-DMDBT的脱除率均可达到100%,表现出良好的活性。循环实验研究表明使用9次后,HSiW/h-BN对DBT的脱除率仍然可以达到93%。分析认为,HSi W的高度分散以及HSiW中W元素的价态变化均有利于催化反应的进行。以离子液体修饰的六方氮化硼(BN-IL)为载体负载磷钼酸(HPMo),成功制备了HPMo/BN-IL多相催化剂。通过X射线光电子能谱(XPS)、拉曼(Raman)、XRD、TEM等表征方法对催化剂进行分析,结果表明多相化后催化剂仍保持h-BN的层状和介孔结构。活性实验研究表明,催化剂对4,6-DMDBT、DBT和3-MBT均表现出优异的催化活性,且循环使用5次后催化剂对4,6-DMDBT的活性仅降低3.7%。分析认为,IL的引入使得HPMo/BN-IL催化剂的活性中心不易脱落,从而提高了催化剂的稳定性。干扰实验研究表明,催化剂在烯烃和芳香烃存在时表现出较好的对硫化物转化选择性。
[Abstract]:In recent years, with the deterioration of oil quality, the sulfur content of fuel increased. SOx produced by fuel combustion can cause serious environmental pollution. Therefore, more and more attention has been paid to the removal of sulfides. Mercaptan and sulfide in fuel oil can be removed by simple physical or chemical methods, while thiophene sulfur is difficult to be removed by traditional hydrodesulfurization technology. For example, biological desulfurization, adsorption desulfurization, extraction desulfurization, oxidation desulfurization, etc. Due to mild reaction conditions and high activity to aromatic sulfides, oxidative desulfurization (ODS) has become a key technology for the production of ultra-low sulfur fuel. ODS technology is to find a high efficient and stable catalyst. In this paper, a series of catalysts have been designed and synthesized. Boron nitride supported heteropoly acid catalyst, Firstly, the graphene type hexagonal boron nitride (h-BN) was used as the carrier, and the phosphotungstate HPWs were loaded into the less layer h-BN by solvothermal method. HPW/h-BN multiphase catalysts were successfully prepared and characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that HPW was successfully confined to the micropores of h-BN. The structure of h-BN has not changed after loading. In ODS system, the catalytic activity of HPW-h-BN p-dibenzothiophene (DBT) and 4-dimethyldimethyldibenzothiophene (4-dimethyldibenzothiophene 44-DMDBT) is excellent. The removal rate of DBT by HPW-h-BN can reach 100%, and the catalyst can be recycled for 6 times. The mechanism analysis shows that, During the reaction, DBT and H _ 2O _ 2 were adsorbed on the surface of the catalyst at the same time, then [PW12O40] _ 3- reactive oxygen species received by H _ 2O _ 2 to form the superoxide species WO _ (2). Finally, DBT was oxidized to DBTO2 by WKO _ (2) to realize the removal of sulfides. HSiW (silicotungstic acid) was loaded into h-BN by impregnation method. HSiW/h-BN multiphase catalyst was successfully prepared. The morphology and structure of the catalyst were analyzed by FTIR and TEM. The results showed that HSiW was highly dispersed on h-BN. The valence of W element in HSiW will change. The removal rate of DBT and 4HSiW / h-BN can reach 100, showing good activity. The cyclic experiment shows that the removal rate of HSiW / h-BN can still reach 93% after 9 times of use of HSiW / h-BN. It is concluded that the removal rate of HSiW / h-BN can reach 93.The results show that the removal rate of HSiW / h-BN can still reach 93% after 9 times of use of HSiW / h-BN. The high dispersion of HPMo/BN-IL and the change of valence state of W element in HSiW were all beneficial to the catalytic reaction. HPMo/BN-IL multiphase catalyst was successfully prepared by using boron nitride (BN-ILL) modified with ionic liquid as the carrier to support HPMoO _ 4. The catalysts were characterized by means of electron spectroscopy (EDS) and Raman Raman spectroscopy (Ram) and X-ray diffraction (XRD) TEM. The results showed that the layered and mesoporous structure of h-BN remained after heterogeneous reaction, and the catalytic activity of the catalyst for 46-DMDBT DBT and 3-MBT was excellent. The activity of the catalyst to 4N 6-DMDBT was only decreased by 3.7% after 5 cycles. It is considered that the introduction of IL makes the active center of HPMo/BN-IL catalyst not easy to fall off, thus improving the stability of the catalyst. In the presence of alkenes and aromatic hydrocarbons, the catalyst exhibited good conversion selectivity to sulfides.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE624.9

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