Preparation of fibrous γ-alumina with large pore volume via co-current dropwise addition method

doi:10.11949/j.issn.0438-1157.20180609

Abstract

Abstract:

A co-current dropwise addition method was employed to prepare γ-alumina with a large pore volume with sodium aluminate (NaAlO₂) and aluminum sulfate (Al₂(SO₄)₃) used as raw materials. The effects of the reaction pH during the precipitation process, raw material concentration, aging pH and adding surfactant sodium dodecyl benzene sulfonate (SDBS) were investigated. It was found that raw material concentration could affect the nucleation-growth process and result in different morphologies, such as irregular sheets, fibers or granules, in which fibers could form the largest pore volume. When the NaAlO₂ concentration was 0.5-0.75 mol/L, the reaction pH was controlled at 8-9.5 and the aging pH was controlled at about 9, the obtained γ-alumina is fibrous. Besides, adding SDBS during the aging process could further improve the pore volume and pore size distribution. The method successfully prepared fibrous γ-alumina with a pore volume of 1.35-2.19 ml/g, a specific surface area of 300-500 m²/g and an average pore diameter of 14-21 nm, a fiber length of 50-60 nm and diameter about 5 nm. It can provide a good catalyst carrier for the residue hydrogenation process.

Key words: NaAlO₂-Al₂(SO₄)₃, precipitation method, γ-alumina, co-current dropwise addition, nucleation-growth, surfactant

摘要：

以偏铝酸钠（NaAlO₂）-硫酸铝（Al₂（SO₄）₃）为原料，利用并流滴加法控制沉淀过程的反应pH，并通过调节原料浓度、老化pH和加入表面活性剂十二烷基苯磺酸钠（SDBS）等方法，成功制备得到了大孔容纤维状的γ-氧化铝。实验发现，不同的原料浓度会影响成核-生长过程，得到不规则片状、纤维状或颗粒状等不同形貌的γ-氧化铝，其中纤维状可形成大孔容。当NaAlO₂浓度为0.5~0.75 mol/L，反应pH控制在8~9.5，老化pH控制在9左右时，得到的γ-氧化铝呈纤维状，孔容较大；此外，在老化过程中添加SDBS可进一步提高孔容，并改善孔径分布。本方法成功制备出孔容为1.35~2.19 ml/g、比表面积为300~500 m²/g、平均孔径为14~21 nm的纤维状γ-氧化铝，纤维长度为50~60 nm，纤维宽度约5 nm，可为渣油加氢过程提供一种性能良好的催化剂载体。

关键词: 偏铝酸钠-硫酸铝, 沉淀法, γ-氧化铝, 并流滴加, 成核-生长, 表面活性剂

CLC Number:

TQ133.1

WAN Yanchun, WANG Yujun, LUO Guangsheng. Preparation of fibrous γ-alumina with large pore volume via co-current dropwise addition method[J]. CIESC Journal, 2018, 69(11): 4840-4847.

万艳春, 王玉军, 骆广生. 并流滴加法制备大孔容纤维状γ-氧化铝[J]. 化工学报, 2018, 69(11): 4840-4847.

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