【作者】 李浩；

【导师】 梁长海； 蒋景阳；

【作者基本信息】 大连理工大学 ， 化学工程， 2025， 硕士

【摘要】 在当前严峻的环境保护和能源压力下,传统的化工能源行业迫切需要向绿色清洁能源方向转型。加氢异构工艺是提升低阶蜡油油品粘温性能,以及通过可再生生物油生产喷气燃料的关键步骤,对于传统化工行业的绿色转型至关重要。通常情况下,加氢异构催化剂由提供加氢脱氢功能的金属组分和提供骨架异构化功能的酸性载体组成。产物的收率与金属组分的担载量、分散度以及担载位置和酸性载体的酸性质、酸强度及孔道结构等性质相关。通过在载体中引入介孔结构以降低反应中间体的扩势能壁垒,或者通过在载体中引入粘结剂并调控金属位点和酸位点之间的距离（金属-酸位点亲密度）的方式提高是近些年加氢异构领域研究的热门方向。为了降低双功能催化剂上的扩散势能壁垒,提高加氢异构反应的选择性,本研究通过将金属Pt担载至γ-Al₂O₃表面然后与ZSM-23分子筛物理混合的方法制备了具有适宜金属-酸位点亲密度的Pt/A+Z双功能催化剂。对催化剂的一系列表征证实,氧化铝的引入在没有损伤分子筛的晶体结构的同时引入了介孔,且金属Pt成功地担载至γ-Al₂O₃表面。Pt/A+Z催化剂降低了反应物分子的扩散阻力,这使其在酸性位点骨架异构之后可以更轻松地扩散至金属位点加氢后脱附,而非继续在沸石分子筛表面的酸性位点过异构后或裂化生成裂化副产物。Pt/A+Z催化剂表现出了优秀的加氢异构性能,在底物转化率为89%时,异构产物达到了最高收率64%。同时对双支链异构产物从支链的位置和间距角度分析,进一步阐明了加氢异构反应产物结构受到反应物分子热力学稳定性和停留时间相互作用影响。由于ZSM-23的微孔结构对反应物分子传质扩散的限制,本文探讨了一种对ZSM-23蒸汽相后处理的方式以在分子筛中引入介孔结构以及保持结晶度。以氢氧化钠（NaOH）和溴化六甲铵（HMBr₂）为后处理试剂,与ZSM-23混合后水热处理。对催化剂的表征显示蒸汽相后处理成功在保持ZSM-23结晶度的同时（>80%）引入了介孔结构。而且后处理导致一部分的四配位骨架铝元素被刻蚀成为非骨架六配位铝元素,这调控了催化剂的酸性质,同时NH₃-TPD表征结果证明蒸汽相后处理使得催化剂暴露出更多的酸性位点。扩散阻力的降低以及载体酸性的调控使得催化剂的正十六烷加氢异构性能得到了显著的提升,Pt/ZSM-NH9催化剂在转化率为87%时,达到了最高的异构产物收率57%。更多还原

【Abstract】 Under the current severe environmental protection and energy pressure,the traditional chemical energy industry urgently needs to transform to the direction of green and clean energy.The hydroisomerization process is a key step to improve the viscositemperature properties of low-order waxed oil products and the production of jet fuel from renewable bio-oil,which is essential for the green transformation of the traditional chemical industry.In general,hydroisomerization catalysts are composed of metal components that provide the function of hydro（dehydro）genation and acidic carriers that provide the function of skeleton isomerization.The yield of the product is related to the metal loading,dispersion and loading position of the metal component,the acid property,acid strength and pore structure of the acid carrier.In recent years,it has been a popular research direction in the field of hydroisomerization to reduce the potential diffusion barrier of reaction intermediates by introducing mesoporous structures in the carrier,or to modify the distance between metal and acid sites（metal-acid intimacy）by introducing binders in the carrier.To reduce the diffusion potential barrier on the bifunctional catalyst and improve the selectivity of hydroisomerization reaction,Pt/A+Z bifunctional catalyst with suitable metal-acid intimacy was prepared by loading metal Pt onto the surface ofγ-Al₂O₃ and then physically mixing it with ZSM-23 zeolite.A series of catalyst characterizations confirmed that the introduction ofγ-Al₂O₃ introduced mesoporous pores without damaging the crystal structure of the zeolite,and the metal Pt was successfully loaded onto the surface ofγ-Al₂O₃.The Pt/A+Z catalyst reduces the diffusion resistance of the reactant molecules,which makes it easier to diffuse to the metal sites for hydrogenation desorption after the acidic site skeleton isomerization,rather than continue to produce cracking products after isomerization on the zeolite surface.The Pt/A+Z catalyst showed excellent hydroisomerization performance and reached the highest yield of 64%at 89%conversion.At the same time,the position and distance of the di-branched isomerism products were analyzed,and it was further clarified that the structure of the hydrogenation isomerism products was influenced by the interaction of thermodynamic stability and residence time.Due to the limitation of the microporous structure of ZSM-23 on the mass transfer of reactants,a vapour phase post-treatment method of ZSM-23 was investigated to introduce the mesoporous structure into the zeolite and maintain the crystallinity.Sodium hydroxide（NaOH）and hexamethylammonium bromide（HMBr₂）were mixed with ZSM-23 for hydrothermal heat treatment.The characterization of the catalyst showed that the vapour phase post-treatment successfully introduced mesoporous structure while maintaining the crystallinity of ZSM-23（>80%）.In addition,the reprocessing results in the etching of a part of the tetracoordinate skeleton Al into non-skeleton hexaordinate Al,which regulates the acid properties of the catalyst.Acidic analysis showed that vapour phase reprocessing exposed more acidic sites.The decrease of diffusion resistance and the regulation of the acidity of the carrier significantly improved the hydrogenation of n-hexadecane.The highest yield of Pt/ZSM-9 catalyst was 57%when the conversion rate was 87%.更多还原