气相法磷改性对USY沸石酸性及其水热稳定性的调控
Improvement of the Acidity and Hydrothermal Stability of USY Zeolite by Phosphorus Modification Using Gas-phase Method
张强 1赵红娟 2李蕊 1王久江 2翟敏慧 1马跃 1夏添 1曾鹏晖 1任申勇 1刘宏海 2高雄厚 2徐春明 1申宝剑1
作者信息
- 1. 中国石油大学(北京)化学工程与环境学院,北京 102249;重质油全国重点实验室,北京 102249;CNPC催化重点实验室,北京 102249
- 2. CNPC催化重点实验室,北京 102249;中国石油天然气股份有限公司石油化工研究院兰州化工研究中心,甘肃 兰州 730060
- 折叠
摘要
磷(P)改性是提高沸石催化剂稳定性的有效方法之一.我们考察了三氯化磷(PCl3)气相法和磷酸氢二铵浸渍法制备得到的不同P改性USY样品.研究发现,2种P改性方法制备的样品中P物种均能够与USY中的Si―OH发生相互作用,同时夺取附近的非骨架 Al物种,将表现为 L酸的 Si―O(EFAl)―Al转变成显示强 B酸的Si―OH―Al.非骨架Al的迁移改善了沸石的孔径分布.在 600℃水热老化后发现,气相法PCl3 改性后样品的桥羟基没有被破坏,其原因是PCl3 改性后样品的P物种主要为低聚态P物种,能够更好地与附近的四配位骨架Al发生相互作用,从而保护沸石的桥羟基不被破坏.而浸渍法磷酸氢二铵改性后样品主要生成高聚态P物种,与附近的四配位骨架Al发生相互作用能力弱,保护沸石桥羟基的作用不强.因此,气相法PCl3 改性样品在 600℃水热老化4 h后的强B酸酸量(41 μmol·g-1)明显高于浸渍法P改性样品(21 μmol·g-1).在 800和 900℃水热老化 4 h后,PCl3 改性样品较浸渍法P改性样品和未改性样品展现了更高的结晶保留度,结合正辛烷催化裂化反应数据,表明气相法PCl3 改性后的USY样品具有更高的催化活性稳定性和结构稳定性.
Abstract
P modification is an effective method to improve the stability of zeolite catalysts.This article discusses the differences between different P-modified USY zeolites prepared by the PCl3 gas-solid reaction method and the conventional(NH4)2HPO4 impregnation method.The study found that the P species of the two P modification methods can interact with the Si―OH in USY,and at the same time capture the nearby non-framework Al species,converting the L acidic(Si―O(EFAl)―Al)into a strong B acid Si―OH―Al.The migration of non-framework Al improves the pore size distribution of zeolite.After hydrothermal aging at 600 ℃,it was found that the zeolite bridge hydroxyl group of the PCl3-modified sample was not destroyed.The reason is that the P species of the PCl3-modified sample was mainly an oligomeric P species,which can better interact with nearby the four-coordinated framework Al interacts to protect the bridge hydroxyl groups of the zeolite.The sample prepared by the impregnation method mainly generates higher polymer P species,which weakly interacts with the nearby four-coordinated framework Al,resulting in little protection for the bridge hydroxyl groups of the zeolite.Therefore,the amount of strong B acid(41 μmol·g-1)of the PCl3 modified sample by the gas phase method was significantly higher than that of the P-modified sample by the impregnation method(21 μmol·g-1)after hydrothermal aging at 600 ℃ for 4 h.After hydrothermal aging at 800 and 900 ℃ for 4 h,the PCl3 modified samples exhibited higher crystallinity retention compared to the impregnation method modified samples and the unmodified samples,combined with the fact that the PCl3-modified sample has the highest n-octane catalytic cracking reaction activity after hydrothermal aging at 600 ℃ for 4 h,all results show that the USY sample modified by gas phase PCl3 has higher catalytic activity stability and structural stability.
关键词
USY沸石/气相法磷改性/酸性改善/水热稳定性Key words
USY zeolite/gas phase phosphorus modification/acidity improvement/hydrothermal stability引用本文复制引用
基金项目
国家自然科学基金创新研究群体项目(22021004)
中国石油科研项目(2022ZG16)
出版年
2024
NETL
NSTL
万方数据