复合模板剂合成SAPO-34分子筛及催化性能研究

发布时间：2019-05-07 05:17

【摘要】：煤制油的核心技术是MTO工艺,MTO工艺的关键问题是高效催化剂的合成。通过查阅文献资料,本文确定了采用水热法合成SAPO-34分子筛,主要研究采用不同比例四乙基氢氧化铵和三乙胺、四乙基氢氧化铵和吗啡啉、三乙胺和吗啡啉复合模板剂来合成SAPO-34分子筛,以及考察不同硅铝比对混合模板剂合成SAPO-34分子筛的影响。通过XRD、SEM、FT-IR、BET、NH3-TPD表征手段来研究合成的SAPO-34分子筛的晶粒尺寸、结构、酸性等。采用四乙基氢氧化铵和三乙胺(2:1)、四乙基氢氧化铵和吗啡啉(2:1)、三乙胺和吗啡啉(2:1)来合成不同硅铝比SAPO-34分子筛,通过MTO反应结果可知其催化寿命在120min-480min之间随着硅铝比的增加而降低,低碳烯烃选择性随着硅铝比的增加也降低但是变化差异很小,低碳烯烃总体选择性基本都在80%以上最高可达90%。复合模板剂合成SAPO-34分子筛比单一模板剂合成的SAPO-34分子筛有着更长的催化寿命,其中四乙基氢氧化铵和三乙胺(2:1),四乙基氢氧化铵和吗啡啉(2:1),三乙胺和吗啡啉(1:1)合成SAPO-34-0.2分子筛的MTO催化效果最好寿命可达420min、480min、360min,低碳烯烃总选择性可达86.6%、89.2%、89.5%。通过GC-MS分析失活后SAPO-34分子筛孔道积碳,主要成分是萘、菲、芘类有机物,这些大分子有机物堵塞孔道使低碳烯烃无法及时扩散出去进一步转化为大分子有机物,同时覆盖催化酸性位最终导致催化剂的失活。
[Abstract]:The key technology of kerosene to oil is MTO process, and the key problem of MTO process is the synthesis of high efficiency catalyst. In this paper, the hydrothermal synthesis of SAPO-34 molecular sieves has been determined by consulting the literature. The main research methods are tetraethyl ammonium hydroxide and triethylamine, tetraethyl ammonium hydroxide and morpholine, and the synthesis of tetraethyl ammonium hydroxide and triethylamine, tetraethyl ammonium hydroxide and morpholine are studied in this paper. The synthesis of SAPO-34 molecular sieves with triethylamine and morpholine composite templates and the effects of different Si-Al ratios on the synthesis of SAPO-34 molecular sieves were investigated. The crystal size, structure and acidity of synthesized SAPO-34 molecular sieves were studied by XRD,SEM,FT-IR,BET,NH3-TPD characterization. Tetraethyl ammonium hydroxide and triethylamine (2:1), tetraethyl ammonium hydroxide and morpholine (2:1), triethylamine and morpholine (2:1) were used to synthesize SAPO-34 molecular sieves with different Si / Al ratios, The results of MTO show that the catalytic life of 120min-480min decreases with the increase of Si-Al ratio, and the selectivity of low-carbon olefins decreases with the increase of Si-Al ratio, but the difference is very small. The overall selectivity of low-carbon olefins is above 80% and the highest is up to 90%. The synthesis of SAPO-34 molecular sieves by composite templates has a longer catalytic life than that of SAPO-34 molecular sieves synthesized by a single template, in which tetraethyl ammonium hydroxide and triethylamine (2:1), tetraethyl ammonium hydroxide and morpholine (2:1), The MTO catalytic activity of triethylamine and morpholine (1:1) for the synthesis of SAPO-34-0.2 molecular sieves can reach 420min, 480min, 360min, the total selectivity of low carbon olefins can reach 86.6%, 89.2%, 89.5%, and the total selectivity of low carbon olefins can reach 86.6%, 89.2% and 89.5% respectively. The carbon deposition in the pores of inactivated SAPO-34 molecular sieve was analyzed by GC-MS, and the main components were naphthalene, phenanthrene and pyrene. These macromolecular organic compounds blocked the pore channels and prevented the diffusion of low carbon olefins into macromolecular organics in time. At the same time, the catalyst was deactivated by covering the acid site of the catalyst.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ529

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