直链烷烃脱氢催化剂载体制备新工艺

A new preparation process of the carriers for straight-chain alkanes dehydrogenation catalyst

研究了以Na Al O2-Al2(SO4)3为原料制备直链烷烃脱氢催化剂载体的工艺,考察p H交替变化对直链烷烃脱氢催化剂载体孔结构的影响,采用XRD、TEM、DTG、DTA、氮吸附-脱附仪和压汞仪等对载体的晶相、粒子形态、结晶水含量、比表面积及孔分布进行表征。结果表明,p H交替变化使拟薄水铝石晶粒尺寸增加,结晶水含量降低,制备出孔容≥1.2 m L·g-1、比表面积≤150 m2·g-1和堆积密度≤0.32 g·m L-1的具有双孔分布的直链烷烃脱氢催化剂载体γ型氧化铝。酸性条件下,大量细小无定形氧化铝迅速溶解,有利于更多细小拟薄水铝石颗粒形成;碱性条件下,这些迅速溶解的无定型氧化铝附着在拟薄水铝石颗粒上,使拟薄水铝石一次粒子逐步长大,结晶度增加。

The preparation process of the carriers for the straight-chain alkanes dehydrogenation catalyst using NaAlO2-Al2（SO4）3 as the raw material was studied. The effects of pH value change on pore structures of the carriers for straight-chain alkanes dehydrogenation catalyst were investigated. The crystalline phases, particle morphology,crystallization water content,surface area and pore size distribution of the as-prepared samples were characterized by XRD,TEM,DTG,DTA,nitrogen adsorption-desorption and mercury poro-simetry techniques. The results showed that pH value change made pseudo boehmite grain size increase and crystallization water content decrease. A straight-chain alkanes dehydrogenation catalyst carrierγ-Al2 O3 with pore volume≥1. 2 mL·g^ - 1 ,surface area≤150 m2 ·g ^- 1 ,bulk density≤0. 32 g·mL ^- 1 and double pore distribution was prepared. Under acid condition,a large number of tiny amorphous alumina was quickly dissolved,which was conducive to the formation of more small pseudo boehmite particles;under alkaline condition,the rapidly dissolved amorphous alumina could deposit on pseudo boehmite particles,which promoted the increase of particle size and the crystallinity of pseudo boehmite.