茂金属催化剂体系及其丙烯聚合性能调控

国内聚丙烯的生产基本上使用传统的Ziegler-Natta催化剂,国外已经使用茂金属催化剂.茂金属催化剂生产的聚丙烯提升了产品性能,市场需求份额逐年增加,国内需要开发茂金属催化剂并拓展工业应用.茂金属催化剂与传统的Ziegler-Natta催化剂相比,结构类型丰富,反应调控能力强,可以催化生成结构多样的聚丙烯.以茂金属催化剂的发展为主线,探讨催化剂结构对反应性能的影响;分析体系中多种因素如温度、压力、催化剂浓度、助剂等对反应活性的调控;讨论催化反应机理.中国石化茂名石化公司基金;;聚烯烃催化技术与高性能材料国家重点实验室基金;;上海市聚烯烃催化技术重点实验室基金(Nos.201501-PT-C01-005,沪CXY-2015-003,16DZ2270800,16DZ2290700);;国家自然科学基金(Nos.21473142,20673191);;教育部创新团队基金(No.IRT_14R31)资助项目~

Advances in Selective Ethylene Oligomerization Based on [PNP]-Ligand Chromium Catalysts

乙烯选择性三聚和四聚催化反应为制备1-己烯和1-辛烯提供了重要途径.在报道和披露的众多结构和组成的催化剂体系中,我们选择[PnP]配位骨架的铬催化剂体系,对其发展和应用进行了综述.论文以结构与催化性能的关联性为主线,阐述[PnP]骨架以及n和P上取代基的电子和立体空间效应对催化性能的影响.从目前的研究态势来看,[PnP]配位骨架的铬催化剂体系在乙烯选择性齐聚生产1-辛烯等线性α-烯烃方面具有发展潜力.The catalytic reaction for the selective ethylene trimerization and tetramerization provides a vital route to the production of 1-hexene and 1-octene.Among the numerous catalysts reported with diverse structures and compositions, we select the [PNP]-ligand based chromium catalysts and focus on illustration on their development and application.This contribution includes seven sections as ethylene(selective) oligomerization catalyst systems, [PNP]-ligand based Cr catalyst system, catalytic mechanism, ethylene oligomerization method, catalytic property, and conclusion and prospect, which will cover almost all of the [PNP]-ligand based Cr catalysts so far studied.In this article, we will mainly discuss the influence on the catalytic property owing to the electronic and/or steric characters of the skeleton as well as the substituents at both N and P atoms of the [PNP]-ligands.In view of the current advances in this field, this [PNP]-ligand based Cr catalyst system is of potencial in application for the production of LAO mainly as 1-octene.聚烯烃催化技术重点实验室基金(No.12DZ2260400); 国家自然科学基金(No.21473142); 教育部创新团队(No.IRT_14R31)资助项目~

MOCVD生长Al_(0.48)Gao_(0.52)N/Al_(0.54)Ga_(0.36)N多量子阱的结构和光学特性

采用金属有机物化学气相淀积(MOCVD)技术,在蓝宝石衬底上生长了Al_(0.48)Gao_(0.52)N/Al_(0.54)Ga_(0.36)N多量子阱(MQWs)结构.通过双晶X射线衍射(DCXRD)、原子力显微镜(AFM)和阴极荧光(CL)等测试技术,分别对样品的结构和光学特性进行了表征.在DCXRD图谱中,可以观察到明显的MQWs衍射卫星峰,通过拟和,MQWs结构中阱和垒的厚度分别为2.1和9.4 nm,Al组分分别为0.48和0.54.在AFM表面形貌图上,可以观察到清晰的台阶流,表明MQWs获得了二维生长;与此同时,MQWs结构存在一些裂缝,主要原因为AlGaNMQWs结构和下层GaN层间存在很大的应力.CL测试表明,AlGaN MQWs结构的发光波长为295 nm,处于深紫外波段,同时观察到处于蓝光、绿光波段的缺陷发光