改性HMS分子筛的制备及催化氧化脱硫性能研究

发布时间：2017-12-27 19:11

本文关键词：改性HMS分子筛的制备及催化氧化脱硫性能研究　出处：《青岛科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：环保问题是当今社会关注的热点问题之一,汽油中硫化物燃烧后会造成严重的大气污染,降低汽油中的硫含量,实现油品的深度脱硫刻不容缓。采用加氢脱硫技术深度脱除噻吩类大分子硫化物必须在更加严苛的操作条件下进行,生产成本也随之提高。氧化脱硫是一种具有广阔应用前景的深度脱硫技术,可以作为加氢脱硫的后续工艺来辅助脱硫。分子筛因其比表面积大、孔径大小可调等优势成为一种被重点研究的氧化脱硫催化剂。本文以纯硅HMS分子筛为研究对象,结合引入金属杂原子、表面有机基团功能化以及负载活性组分等方式对其进行改性,制备了一系列氧化脱硫催化剂,采用XRD、FT-TR、SEM、TEM、N2吸附脱附、UV-Vis等手段对催化剂样品进行表征分析,并以模型油中噻吩的氧化脱除为探针反应对催化剂的催化氧化脱硫性能进行研究。主要内容如下:(1)采用液相回流浸渍法对HMS分子筛进行表面氨基改性,以改性后的分子筛为载体、磷钨酸为活性组分制备了HPW-NH_2-HMS催化剂。表征结果显示,催化剂保留了HMS分子筛的介孔结构和磷钨酸的Keggin结构。将催化剂用于氧化脱硫反应,考察不同条件对催化剂氧化脱硫性能的影响。结果表明,在反应温度为60℃、n(H2O2)/n(S)=8、25%HPW-NH_2-HMS催化剂用量0.1 g·(10 mL)~(-1)、反应时间120 min的条件下,噻吩的氧化脱除率可达93.89%。氧化脱硫反应动力学研究发现,在以噻吩/正辛烷为模型油、30%(wt)双氧水为氧化剂、25%HPW-NH_2-HMS为催化剂的反应体系中,噻吩的氧化反应为一级反应,反应的活化能为31.9 KJ/mol。(2)采用超声浸渍法对原位合成的Ti-HMS分子筛进行负载金属改性,制备了Fe/Ti-HMS、Cu/Ti-HMS和Zn/Ti-HMS催化剂。对催化剂的结构和形貌进行表征,结果显示,Ti-HMS分子筛具有介孔孔道结构,金属组分均匀的分散在分子筛的表面。氧化脱硫实验结果表明,金属组分的存在可以有效地提高催化剂的催化活性,负载金属组分的催化剂催化活性由大到小依次为Zn/Ti-HMS㧐Cu/Ti-HMS㧐Fe/Ti-HMS。(3)采用液相回流浸渍法对原位合成的Fe-HMS分子筛进行表面氨基改性,通过表面接枝的氨基基团来络合固载Cu~(2+),制备了Cu~(2+)/Fe-HMS类芬顿催化剂。Fe元素成功地进入分子筛的骨架中,表面接枝氨基和络合固载铜离子后催化剂的比表面积、孔体积和孔径等参数均有所降低。将催化剂用于氧化脱硫反应,结果表明表面铜离子和骨架铁表现出协同作用,铜离子对噻吩分子的选择吸附性使其被优先吸附到催化剂的表面,骨架铁催化过氧化氢生成羟基自由基,两种反应物在催化剂表面不断的积累,促进了氧化反应的进行。
[Abstract]:Environmental protection is one of the hot issues in today's society. The combustion of sulfide in gasoline will cause serious air pollution and reduce sulfur content in gasoline, so it is urgent to achieve deep desulfurization of oil. The use of hydrodesulfurization technology to remove thiophene macromolecular sulfides must be carried out under more stringent operating conditions, and the cost of production is also increased. Oxidative desulfurization is a kind of deep desulfurization technology with broad application prospects, which can be used as a follow-up process for hydrodesulfurization to assist the desulfurization. Molecular sieves have become one of the most important catalysts for oxidative desulfurization because of their large specific surface area and adjustable pore size. The YISHION silicon HMS molecular sieve as the research object, modified by the combination of introducing metal atoms, surface organic functional groups and active component load, a series of oxidation desulfurization catalyst prepared by XRD, FT-TR, SEM, TEM, N2 adsorption desorption, UV-Vis catalyst samples were characterized by means of analysis and Study on properties of catalytic oxidation desulfurization catalyst to probe reaction to oxidative desulfurization of thiophene as model oil. The main contents are as follows: (1) liquid phase reflux impregnation method was used to modify the surface of HMS zeolite, and the HPW-NH_2-HMS catalyst was prepared by using modified molecular sieve as carrier and phosphotungstic acid as active component. The characterization results showed that the catalyst retained the mesoporous structure of HMS molecular sieve and the Keggin structure of phosphotungstic acid. The effect of different conditions on the oxidation desulfurization performance of the catalyst was investigated by using the catalyst for oxidation desulfurization. The results showed that the oxidation removal rate of thiophene could reach 93.89% at the reaction temperature of 60, n (H2O2) /n (S) =8, 25%HPW-NH_2-HMS catalyst dosage 0.1 g ~ (10 mL) ~ (-1) and reaction time 120 min. Kinetic studies on oxidative desulfurization showed that thiophene oxidation reaction was first order reaction in the reaction system of thiophene / octane as model oil, 30% (WT) hydrogen peroxide as oxidant and 25%HPW-NH_2-HMS as catalyst, and the activation energy of reaction was 31.9 KJ/mol. (2) Ti-HMS molecular sieves in situ synthesized by ultrasonic impregnation are modified by metal loading, and the catalysts of Fe/Ti-HMS, Cu/Ti-HMS and Zn/Ti-HMS are prepared. The structure and morphology of the catalyst were characterized. The results showed that the Ti-HMS molecular sieve had mesoporous pore structure and the metal component was dispersed evenly on the surface of the molecular sieve. The results of oxidative desulfurization experiments show that the presence of metal components can effectively improve the catalytic activity of the catalysts. The catalytic activity of supported metal components is Zn/Ti-HMS to Cu/Ti-HMS Fe/Ti-HMS from large to small. (3) liquid phase reflux impregnation method was used to modify the surface of Fe-HMS zeolite synthesized in situ. The Cu~ (2+) /Fe-HMS Fenton like catalyst was prepared by complexing Cu~ (2+) with surface grafting amino group. The Fe element successfully entered the skeleton of the zeolite. The surface area, pore volume and pore size of the catalyst decreased after grafting with amino groups and complexing with copper ions. The catalyst for oxidative desulfurization reaction, the results showed that the surface of copper ion and iron skeleton showed synergistic effect of selective adsorption of copper ions on the thiophene molecules to be preferentially adsorbed to the surface of the catalyst skeleton iron catalyzed hydrogen peroxide generation of hydroxyl radicals, two kinds of reactants on the catalyst surface and the accumulation promoted oxidation reaction the.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE624.9

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