Abstract Amorphous silica-aluminas with enhanced Bronsted acidity have been successfully synthesized via a novel acetic acid based sol-gel process. The resulting amorphous silica-aluminas possess an irregular spherical morphology, homogeneously element dispersion, and a high external surface area in the range of 374–594 m2/g with little contribution from micropores. By simply adjusting the molar Si/Al ratio in the synthesis precursor solution from 0.5 to 2.0, the total Bronsted acid site density firstly increases and then slightly decreases, consistent with the trend of summarized molar content of four and five-coordinated aluminum species. Among them, the amorphous silica-alumina with initial Si/Al ratio of 1.5 exhibits the highest Bronsted acid site density, and its supported Pt catalyst performs the highest activity resembling that of HBeta-based catalyst in the hydroisomerization of n-hexadecane. Meanwhile, a superior catalytic selectivity to multibranched isomers was received over the amorphous silica-alumina without strong Bronsted acid sites. Moreover, a remarkable stability (>2000 h) was also achieved in the hydrocracking of Fischer-Tropsch wax under industrially relevant reaction conditions. This sol-gel synthesis process provides a facile method to prepare amorphous silica-aluminas with outstanding texture and acid properties for catalytic refining in petrochemical fields.

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酸性增强型无定形二氧化硅-氧化铝的合成与表征及其在加氢异构化/裂解中的应用

摘要 通过新型醋酸溶胶-凝胶工艺成功合成了布朗斯台德酸性增强的无定形二氧化硅-氧化铝。所得的无定形二氧化硅-氧化铝具有不规则的球形形态、均匀的元素分散以及在 374-594 m2/g 范围内的高外表面积，微孔的贡献很小。通过简单地将合成前驱体溶液中的 Si/Al 摩尔比从 0.5 调整到 2.0，总布朗斯台德酸位点密度先增加后略有下降，与四、五配位铝物种的摩尔含量汇总趋势一致。其中，初始 Si/Al 比为 1.5 的无定形二氧化硅-氧化铝表现出最高的布朗斯台德酸位点密度，其负载的铂催化剂在正十六烷的加氢异构化中表现出与基于HBeta的催化剂相似的最高活性。同时，与无强布朗斯台德酸位点的无定形二氧化硅-氧化铝相比，对多支化异构体具有优异的催化选择性。此外，在工业相关反应条件下，费托蜡的加氢裂化也获得了显着的稳定性（>2000 小时）。这种溶胶-凝胶合成工艺提供了一种简便的方法来制备具有出色质地和酸性特性的无定形二氧化硅-氧化铝，用于石化领域的催化精制。在工业相关反应条件下，费托蜡的加氢裂化也实现了显着的稳定性（>2000 小时）。这种溶胶-凝胶合成工艺提供了一种简便的方法来制备具有出色质地和酸性特性的无定形二氧化硅-氧化铝，用于石化领域的催化精制。在工业相关反应条件下，费托蜡的加氢裂化也实现了显着的稳定性（>2000 小时）。这种溶胶-凝胶合成工艺提供了一种简便的方法来制备具有出色质地和酸性特性的无定形二氧化硅-氧化铝，用于石化领域的催化精制。