Pd-La/镁铝尖晶石催化剂上气相胺化法合成2,6-二异丙基苯胺  

Synthesis of 2,6-Diisopropylaniline by Gas-Phase Amination on Mg-Al Spinel-Supported Pd-La Catalyst

作　　者：姜瑞霞[1] 谢在库[2] 张成芳[1] 陈庆龄[2] 

机构地区：[1]华东理工大学化工工艺研究所,上海200237 [2]中国石油化工股份有限公司上海石油化工研究院,上海201208

出　　处：《催化学报》2003年第7期489-493,共5页

摘　　要：采用硝酸铝和硝酸镁混合溶液浸渍氧化铝 ,干燥后高温焙烧制得尖晶石载体 ,再用氯化钯和硝酸镧混合溶液浸渍该载体 ,制成Pd La/尖晶石催化剂 .研究了该催化剂上的气相胺化合成 2 ,6 二异丙基苯胺 .采用BET孔结构测试和XRD ,TG ,FT IR及SEM等手段对新鲜及失活催化剂进行了表征 ,考察了胺化反应前后催化剂性质的变化 .结果表明 ,失活催化剂上的积碳分别沉积在金属和载体上 ,这两种不同性质的积碳可分别在 2 42和 32 4℃燃烧 ,积碳中含有芳环、脂环、烷基、稠环芳烃和胺基物 .催化剂的失活是由于气相胺化反应产物 2 ,6 二异丙基苯胺和中间产物 2 ,6 二异丙基环己胺均为碱性的大分子物质 ,它们容易吸附在催化剂的酸性载体上 ,并进一步生成更大的分子而形成积碳 .diisopropylaniline ( 2,6-DIPA) is an important intermediate in organic chemical industry. The methods to synthesize 2,6-DIPA have been developed in two different ways, alkylation of aniline and gas-phase amination of 2,6-diisopropylphenol ( 2,6-DIPP). The gas-phase amination is an ideal method for the synthesis of 2,6-DIPA for its high conversion and selectivity, but the reaction condition (such as space velocity) and catalyst stability still need to be improved. In this paper, the magnesia-alumina spinel support was prepared by impregnating Al 2O 3 with an aqueous solution of aluminium nitrate and magnesium nitrate and then calcinating at high temperature. The Pd-La/spinel catalyst was obtained by impregnating the spinel support with an aqueous solution of palladium chloride and lanthanum nitrate and used in the gas-phase amination of 2,6-DIPP at a high liquid hourly space velocity of 0.3 h -1 for a relative long time of 300 h. The conversion of 2,6-DIPP, selectivity for 2,6-DIPA, and yield of 2,6-DIPA dropped from 98.5%, 88.9%, and 87.5% to 61.8%, 69.3%, and 42.8%, respectively, after reaction for 480 h. The fresh and coked catalysts were characterized by BET surface area, XRD, TGA, and SEM measurements. The results showed that the two kinds of coke formed on the metal and the support could be burnt up at about 242 and 324 ℃, respectively. The coke contains aromatic and aliphatic rings, alkyl groups, condensed ring aromatic hydrocarbon, and amine groups. The reason for catalyst deactivation can be explained as follows: both the product 2,6-DIPA and the intermediate product 2,6-diisopropylcyclohexamine are large basic molecules, they can adsorb on the acid catalyst support easily and generate larger molecules that form carbon deposit on the catalyst through polymerization. The basic promoter La can neutralize the strong acid sites on the catalyst and inhibit the formation of carbon deposit.

关 键 词：钯 镧 镁铝尖晶石 负载型催化剂 2 6-二异丙基苯酚 气相胺化 2 6-二异丙基苯胺 积碳 催化剂失活 

分 类 号：O643.3[理学—物理化学]