非負(fù)載過渡金屬硫化物熱解法制備及催化性能
發(fā)布時(shí)間：2018-07-07 16:03
本文選題：過渡金屬硫化物 + 程序升溫?zé)峤?/strong>��； 參考：《大連理工大學(xué)》2010年碩士論文
【摘要】： 負(fù)載型過渡金屬硫化物催化劑廣泛應(yīng)用于油品的加氫精制過程以及化學(xué)品的選擇加氫等領(lǐng)域。然而由于活性中心與載體的強(qiáng)相互作用降低了負(fù)載型過渡金屬硫化物催化劑的催化性能,因此,研發(fā)高比表面積的非負(fù)載過渡金屬硫化物催化材料對于提高加氫精制反應(yīng)活性,降低油品中硫氮含量具有重要的理論和應(yīng)用意義。 本文采用單源前體程序升溫直接熱解的方法制備得到了一系列過渡金屬硫化物催化材料。常溫常壓下成功合成了四硫代鉬酸銨、四硫代鎢酸銨、四甲基四硫代鉬酸銨、四甲基四硫代鎢酸銨、十六烷基三甲基四硫代鉬酸銨和十六烷基三甲基四硫代鎢酸銨等單源硫代過渡金屬鹽前體。 采用單源前體直接熱解法制備了具有不同的比表面積和孔道特征的非負(fù)載MoS2、WS2和Ni/MoS2催化材料。其中四甲基四硫代鉬酸銨、十六烷基三甲基四硫代鉬酸銨和十六烷基三甲基四硫代鎢酸銨熱解得到的MoS2和WS2的比表面積在100m2/g以上,以十六烷基三甲基四硫代鎢酸銨或鉬酸銨熱解得到的催化劑以微孔為主,而四甲基四硫代鎢酸銨或鉬酸銨熱解得到的催化劑以中孔為主。所制備的過渡金屬硫化物催化劑具有典型MoS2或WS2特征峰,但晶化程度弱,而WS2的晶化程度明顯高于MoS2。Ni的摻雜進(jìn)一步降低MoS2晶化程度,但仍保留了MoS2的衍射峰,觀察不到NiS的衍射峰,表明NiS粒子很小且Ni元素在樣品中的分布均勻。透射電鏡照片顯示了明顯的MoS2粒子(002)晶面的晶格條紋。雜亂無章的MoS2粒子主要由3-4層組成,層長度約為3-8nm。隨Ni含量的增加,MoS2粒子相互交聯(lián)生成片層狀的MoS2。非負(fù)載MoS2、WS2和Ni/MoS2催化劑在喹啉選擇加氫中顯示出較高的催化活性和對1,2,3,4-四氫喹啉的高選擇性。 通過MCM-41模板劑十六烷基三甲基溴化銨和四硫代鉬酸銨反應(yīng),在MCM-41孔道內(nèi)合成了十六烷基三甲基四硫代鉬酸銨,直接熱分解制備得到的MoS2/MCM-41催化材料。BET、XRD、TEM和EDS等表征顯示,MCM-41有序中孔結(jié)構(gòu)沒有被破壞,但MoS2納米粒子的形成改變了載體的孔徑分布,減小了載體的孔容。MoS2粒子的分布位置主要在MCM-41載體的端部和孔道內(nèi)部。隨著MoS2擔(dān)載量的增加,MoS2/MCM-41催化劑對DBT加氫脫硫活性呈現(xiàn)先增加后減小的趨勢,而MoS2/MCM-41只有直接脫硫途徑,表明此MoS2/MCM-41催化劑主要是通過氫解過程達(dá)到脫硫目的的。
[Abstract]:Supported transition metal sulphide catalysts are widely used in the hydrofining process of oil products and the selective hydrogenation of chemicals. However, because the strong interaction between the active center and the support reduces the catalytic performance of the supported transition metal sulphide catalyst, therefore, the development of non-supported transition metal sulfide catalyst material with high specific surface area can improve the hydrofining reaction activity. It is of great theoretical and practical significance to reduce the content of sulfur and nitrogen in oil. In this paper, a series of transition metal sulphide catalytic materials were prepared by single source precursor programmed pyrolysis. Ammonium tetrathiomolybdate, ammonium tetrathioate, ammonium tetramethylammonium tetrathiomolybdate and ammonium tetramethyl tetrathiotungstate were successfully synthesized at room temperature and atmospheric pressure. Single source transition metal salts such as cetyltrimethyl ammonium tetrathiomolybdate and cetyltrimethylammonium tetrathiotungstate were used. Unloaded MoS _ 2W _ 2 and Ni / MoS _ 2 catalytic materials with different specific surface area and pore characteristics were prepared by direct pyrolysis of single precursor. The specific surface areas of MoS2 and WS2 obtained by pyrolysis of ammonium tetramethyl tetrathiomolybdate, cetyltrimethylammonium tetrathiomolybdate and cetyltrimethyl ammonium tetrathioate are above 100m2/g. The catalysts obtained by pyrolysis of cetyltrimethylammonium tetrathiotungstate or ammonium molybdate are mainly microporous, while the catalysts obtained by pyrolysis of tetramethyl ammonium tetrathioate or ammonium molybdate are mesoporous. The transition metal sulphide catalysts prepared have typical MoS2 or WS2 characteristic peaks, but the degree of crystallization is weak, and the degree of crystallization of WS2 is significantly higher than that of MoS2.Ni doping, but the diffraction peak of MoS2 is retained. The diffraction peaks of NIS were not observed, which indicated that the particles of NiS were very small and the distribution of Ni elements in the samples was uniform. Transmission electron microscopy (TEM) photographs show the lattice stripes of the (002) surface of the MoS2 particles. The disordered MoS2 particles are mainly composed of 3-4 layers, the length of which is about 3-8 nm. With the increase of Ni content, MoS _ 2 particles crosslinked each other to form lamellar MoS _ 2. The unsupported MoS _ 2W _ 2 and Ni / MoS _ 2 catalysts showed high catalytic activity and high selectivity for 1H _ 2N _ 3H _ 3H _ 4H _ 4 quinoline in the selective hydrogenation of quinoline. Cetyltrimethylammonium tetrathiomolybdate was synthesized in MCM-41 pore channel by the reaction of cetyltrimethylammonium bromide with ammonium tetrathiomolybdate. The characterization of MoS _ 2 / MCM-41 catalyst material. BETN XRDX TEM and EDS showed that the ordered mesoporous structure of MCM-41 was not destroyed, but the formation of MoS2 nanoparticles changed the pore size distribution of the support. The distribution of MoS2 particles is mainly located in the end and inside of MCM-41 carrier. With the increase of MoS _ 2 loading, the activity of MoS _ 2 / MCM-41 catalyst for DBT hydrodesulfurization increased first and then decreased, while MoS _ 2 / MCM-41 had only direct desulfurization pathway, which indicated that the MoS _ 2 / MCM-41 catalyst was mainly desulphurized by hydrogenolysis.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2010
【分類號】：O643.36
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