分子筛负载Pt催化剂酸性位点调控及对蒽深度加氢性能的影响

Regulation of catalyst acid sites and its effect on the deep hydrogenation performance of anthracene

对煤焦油中稠环芳烃深度加氢是制备煤基高能量密度燃料的有效方法。为解决稠环芳烃特有的电子结构和位阻效应影响其加氢饱和程度以及提高催化剂的酸性和反应条件会导致裂解产物的增加、全氢产物的选择性下降问题,本文使用Al-SBA15与USY分子筛,通过水热合成方法制备酸性适中的复合介-微孔载体,通过等体积浸渍法将贵金属Pt负载在复合酸性载体上,经蒽饱和加氢探针反应研究发现,当总酸量为144.4μmol/g时,全氢蒽的选择性达到99%。通过电镜分析表征发现水热复合后Pt/Al-SBA15+USY催化剂形貌呈棒状,其内部为USY,外部为Al-SBA15,此时Pt/Al-SBA15+USY保持各自原有的孔径,分别为9.6nm和0.8nm左右。Pt纳米颗粒有较高的分散性,最优尺寸为3.03nm。对比分析显示,Al-SBA15与USY分子筛水热合成制备的复合载体,其酸量较二者机械混合后的分子筛载体酸量有所降低,从而导致饱和加氢反应能力提升。

Deep hydrogenation of polycyclic aromatic hydrocarbons(PAHs)in coal tar is an effective method to prepare coal-based high energy density fuel.Due to the unique electronic structure and steric hindrance effect,present catalysts show insufficient capacity for deep hydrogenation of PAHs.In addition,increasing the acidity of catalyst and reaction conditions will lead to the increase of cracking products and the decrease of selectivity of perhydro-products.In this study,Al-SBA15 and USY were used to prepare composite meso-microporous supports with moderate acidity by hydrothermal synthesis.The noble metal Pt was loaded on the composite acid support by equi-volume impregnation.The saturation hydrogenation performance of the synthesized composite catalyst for the model compound anthracene was studied.The results showed that the selectivity of perhydroanthracene could reach about 99%when Brønsted acid content was 144.4μmol/g.TEM and SEM results showed that the Pt/Al-SBA15+USY catalyst was rod-like after hydrothermal recombination with USY inside and Al-SBA15 outside.The composite support maintained the original pore size of about 9.6nm and 0.8nm,respectively.Pt nanoparticles had high dispersion and the optimal size was 3.03nm.Comparative analysis showed that the acid content of the composite support prepared by hydrothermal synthesis of Al-SBA15 and USY molecular sieve was lower than that of the molecular sieve support after direct mixing.Thus,the capacity of saturated hydrogenation was improved.