导　　师： 张昕

学科专业： 081701

授予学位： 硕士

作　　者： ;

机构地区： 西北大学

摘　　要： 丙烯是十分重要的基础化工原料,广泛应用于生产丙烯腈、丙烯酸、聚丙烯、环氧丙烷、丙酮等。由于丙烯市场供求关系的日益紧张,特别是丙烯下游产品需求增加的拉动,丙烯的价格快速攀升。传统丙烯生产主要依赖于蒸汽裂解和催化裂化等石化工艺过程。石油资源的日益缺乏,难以满足日益增长的丙烯需求,迫切需要改进传统路线和寻求新的生产工艺。因此,致力于非石油路线生产丙烯已经引起了世界各国的关注。 生物质乙醇生产日趋成熟,为乙醇制丙烯生产路线提供了充足的原料来源。以生物质乙醇为原料生产丙烯的技术不但能够将生物化工和有机化工有效结合,还体现了碳中和/(Carbon neutral/)这一低碳环保的理念。 本论文制备了不同粒径和不同硅铝比的超细HZSM-5分子筛催化剂。采用X-射线衍射/(XRD/)、傅里叶红外光谱/(FT-IR/)、N2等温线吸附-脱附/(BET/)、扫描电子显微镜/(SEM/)和氨程序升温脱附/(NH3-TPD/)等表征技术对超细HZSM-5分子筛的体相结构、表面性质以及酸中心等进行了研究；考察了超细HZSM-5分子筛的晶粒大小和硅铝比对催化性能的影响,并结合热力学计算优选了超细HZSM-5分子筛上乙醇制丙烯的反应条件；另外,采用浸渍法以规整金属填料/(ZT-45、ZT-60、ZT-90/)、乱堆金属丝网填料/(Mesh packing/)为载体制备超细HZSM-5整体催化剂,考察了催化剂的传质、传热性质对其催化性能和优选的反应条件的影响。 主要研究结果如下： /(1/) HZSM-5分子筛粒径越小,比表面积越高,孔体积越大,催化活性和稳定性越高；适宜的硅铝比/(Si//Al2=60/)具有适宜的总酸量和弱酸含量有利于丙烯收率的提高。 /(2/)在最优反应条件/(0.1MPa、773K、PEthanol=23kPa、WHSV=2.85h-1/)下,超细/]HZSM-5/(Si//Al2=60/)分子筛上的丙烯收率为34.4/%；反应6h稳定性良好。 /(3/)使用规整金属填料作为催化剂载体改善了催化剂床层的传质、传热性能,提高了丙烯的时空收率和催化剂稳定性。以规整金属填料ZT-60为载体的超细HZSM-5/(Si//Al2=60/)整体催化剂在最优条件下的丙烯时空收率为0.73kg-C3H6//h//kg-cat. Propylene is important fundamental chemical material and widely used in the production of acrylonitrile, acrylic, polypropylene, acetone, epoxy propane, etc.. Nowadays, the propylene mainly produced from the petroleum processing such as steam cracking and catalytic cracking. However, due to the drastic market demand of propylene and the shortage of oil, the price of propylene constantly increases. Therefore, it is necessary to develop non-petroleum and new technology for increasing the production of propylene. Up to date, the production of bio-ethanol has gained great breakthrough, which supplies an opportunity to develop an attractive technology for the conversion of ethanol to propylene. It is considered that the conversion of bio-ethanol to propylene combines the bio-chemical engineering and organic chemical engineering well. Such route is considered to be carbon Neutral route for the production of propylene. In this thesis, the ultrafine HZSM-5zeolite with different crystal size and Si//Al2ratio has been prepared. The X-ray diffraction /(XRD/), Fourier transform infrared spectroscopy /(FT-IR/), N2isotherm adsorption-desorption /(BET/), Scanning electron microscopy /(SEM/) and Programmed desorption of ammonia /(NH3-TPD/) are used to characterize the bulk structure, surface properties and acidity of ultrafine HZSM-5zeolite. The effect of crystal size and Si//Al2ratio on the properties and catalytic performance of ultrafine HZSM-5zeolite was investigated. The optimal reaction conditions of ethanol conversion to propylene were obtained by thermodynamic calculations and experiments. Structured metal packing /(ZT-45, ZT-60, ZT-90/) and disordered mesh packing were used as support for preparing supported ultrafine HZSM-5catalysts by impregnation method. The influences of those supports on mass transfer, heat transfer, catalytic performance and optimal conditions were investigated. The main results are shown as follows: /(1/) The smaller the particle size of HZSM-5zeolite, the higher specific surface area and pore volume, and the catalytic activity and stability will be better. For gaining the high propylene yield, it is necessary that the catalyst shall have proper Si//Al2ratio and the acidity. /(2/) Under the optimal reaction conditions /(0.1MPa,773K, P Ethanol=23kPa, WHSV=2.85h-1/), ultrafine HZSM-5zeolite /(Si//Al2=60/) showed the highest propylene yield of ca.34.4/%and good stability in TOS of6h. /(3/) Structured metal packing played great influences on the mass transfer, heat transfer of the catalysts, which in turn determined the propylene yield and catalyst stability. The supported ultrafine HZSM-5zeolite /(Si//Al2=60/) with ZT-60structured metal packing showed the highest propylene space-time yield of0.73kg-C3H6//h//kg-cat under the optimal reaction conditions.

关 键 词： 乙醇 丙烯 超细 分子筛 载体 整体催化剂

分 类 号： [TQ426]

领　　域： [化学工程]