【作者】 王雅菁；

【导师】 赵瑞玉； 刘晨光；

【作者基本信息】 中国石油大学 ， 化学工程与技术， 2010， 硕士

【摘要】 本论文采用炭黑扩孔的方法制备出孔径较大且孔分布集中的γ-Al₂O₃载体,利用ZSM-5和β分子筛纳米簇对其进行表面改性,并以其为载体制备加氢脱硫催化剂。载体扩孔方面,主要考察了炭黑类型、炭黑用量及炭黑分散性（如分散剂的化学结构、用量等）对γ-Al₂O₃孔径分布的影响;分子筛纳米簇的合成方面,在无碱金属离子存在的条件下,分别合成出含有ZSM-5和β沸石次级结构单元（或分子筛纳米簇）的溶液,主要考察了晶化温度、晶化时间、硅铝比等制备条件对分子筛纳米簇性质的影响;载体改性方面,重点考察了改性前后载体的酸性、孔结构等表面性质的变化。论文采用XRD、IR、Py-IR、BET和NH3-TPD等手段进行了表征。结果表明,采用分散剂分散法可在较低炭黑用量下取得良好的扩孔效果,使γ-Al₂O₃载体的孔径分布更集中于10²0nm或大于20nm的范围;在最佳制备条件下合成的纳米簇溶液澄清透明,无微孔分子筛微晶的生成,且其粒径较小,适合用于对γ-Al₂O₃载体的改性,其中ZSM-5纳米簇的最可几粒径明显小于β纳米簇;经分子筛纳米簇改性后载体的酸性明显增强并出现一定B酸位,且孔结构无明显变化,其中ZSM-5纳米簇改性样品较β纳米簇具有更强的酸性位和更均匀的分布。论文以分子筛纳米簇改性前后的γ-Al₂O₃为载体,制备负载型Ni-Mo加氢精制催化剂,并以DBT为模型化合物考察其加氢脱硫性能。结果表明,与传统γ-Al₂O₃载体制备的催化剂相比,经分子筛纳米簇改性后,催化剂的酸性大大提高,活性组分的堆垛层数及片层长度明显增加,DBT在分子筛纳米簇改性催化剂上的转化率和脱硫率都大幅提高,反应途径虽然仍以氢解路径为主,但加氢路径所占比例明显增大,其中扩孔后载体对应的催化剂较扩孔前具有更高的加氢脱硫活性。更多还原

【Abstract】 In this paper, theγ-Al₂O₃ carrier with large pore diameter and appropriate pore size distribution was firstly prepared by using carbon black as enlarge agent, followed by the modification with ZSM-5 andβzeolite nanoclusters respectively, and used as the support of the hydrodesulfurization catalysts.For the pore enlargement ofγ-Al₂O₃ carrier, the effects of carbon black types, content and dispersion in theγ-Al₂O₃ power, such as the chemical properties and content of surfactant dispersant, on the pore distribution ofγ-Al₂O₃ were studied. The zeolite nanoclusters solution containing ZSM-5 andβzeolite secondary building units was synthesized in the absence of alkali metal ions respectively. The influences of crystallization temperature, crystallization time and the ratio of Si/Al were also examined. In the surface modification ofγ-Al₂O₃, the changes of the acidity and pore structure property before and after modification with zeolite nanoclusters were investigated.The samples were characterized by XRD, Py-IR, BET, NH3-TPD and EDS analytical techniques. The XRD and FT-IR results showed that no zeolite crystalline particle was detected in the clear solution （or zeolite nanoclusters） synthesized under the optimum synthesis conditions, and the nanoclusters particle size was suitable for the modification ofγ-Al₂O₃ carrier. In addition, the most probable particle size of ZSM-5 nanoclusters was smaller than ofβnanoclusters. The pore-enlargedγ-Al₂O₃ support with a large specific surface area, appropriate pore size distribution and sufficient mechanical strength was prepared by the Surfactant Dispersion Method （SDM）. The acidity ofγ-Al₂O₃ support modified with zeolite nanoclusters was greatly improved, however, the changes of pore structure were unconspicuous. The EDS results revealed that the zeolite nanoclusters uniformly distributed in the modifiedγ-Al₂O₃ support, and the carrier modified with ZSM-5 nanoclusters had stronger acid strengthen and more uniform distribution than ofβnanoclusters.The hydrotreating catalysts were prepared by impregnating active components Ni-Mo onto the traditionalγ-Al₂O₃ and modifiedγ-Al₂O₃ respectively. The activity and selectivity of the catalysts in the HDS of DBT were also evaluated in a fixed-bed high pressure micro-reactor. Compared to the traditional catalyst, the catalyst modified with zeolite nanoclusters had stronger acidity, higher stacking number of active phase and improved HDS activity. It was found that although the DBT removal on the both catalysts occurred mainly through the hydrogenolysis route, the HDS proportion through the hydrogenation route was increased greatly on the modified catalyst, associated to the increased feed stock conversion and desulfurization rate. The catalyst using pore-enlargedγ-Al₂O₃ as carrier had higher HDS activity than that of traditional carrier.更多还原