苯与长链烯烃烷基化反应纳米薄层分子筛催化剂的设计合成及催化机理研究

目前，苯与长链烯烃烷基化反应生产直链烷基苯（LAB）主要采用以氢氟酸为催化剂的烷基化工艺，存在安全生产、环境保护以及2-苯基异构体（2-P）选择性低等问题，而以分子筛为固体催化剂的绿色替代工艺成为LAB生产技术发展的必然趋势。针对烷基化反应中分子筛催化剂易结焦失活的难题，本项目提出借助纳米薄层分子筛酸中心易接近、传质扩散阻力小、层数与酸性可调的特点，强化烷基化反应中烯烃碳正离子与苯的快速反应和扩散，从而提高烯烃转化率和催化剂稳定性。拟采用含聚氧乙烯基链的新型季铵盐表面活性剂阻断层状分子筛合成过程片层之间有序组装排列，实现纳米薄层分子筛的水热一步合成以及对层板数量和酸性的调控。系统研究纳米薄层分子筛烷基化催化性能，揭示纳米薄层分子筛层板数量、孔结构以及酸中心强度和分布等因素对长链烯烃转化率、LAB选择性和稳定性的影响机制，为高活性、高稳定性和高2-P选择性分子筛催化剂的优化设计提供理论指导。

At present, the synthesis of linear alkylbenzene (LAB) by alkylation of benzene with long chain olefin is using HF as a homogeneous catalyst. However, HF homogenous catalyst are inevitable of environmental pollution, equipment corrosion, and separation disadvantages. Moreover, the selectivity of 2-phenyl isomer with better emulsibility characteristics is very lower. Thus, the environmentally benign process using solid acid as catalyst is the development trend for LAB synthesis. Many zeolite catalysts for LAB synthesis have been reported in the literature, such as H-Beta, HY, mordenite and MCM-22, etc. However, the serious deactivation problem of zeolites hindered their industrial application. Based on the accessibility of acidic sites and shorter diffusion path over MWW zeolite nanosheets, in this project, an idea on the design of MWW zeolite nanosheets for alkylation of benzene to promote the reactivity of carbocation and diffusion rate of product, which will improve the conversion of long chain olefin and stability of zeolite catalysts. Herein, we proposed that by using a novel quaternary ammonium salt with polyoxyethylene group chain and long-chain alkyl group to prevent the ordered assemble of MWW nanosheets in MCM-22 zeolite. Consequently, the MWW zeolite nanosheets with different number of nanosheets will be obtained. The olefin conversion, selectivity of LAB, and the stability of zeolite nanosheets will quantitatively correlated with the structure and acidity of the zeolite nanosheets. The influencing mechanism of the number of nanosheets and the acidic properties of MWW zeolite nanosheets on the olefin conversion and distribution of LAB will be determined, which will provide the theoretical direction for development of a high-performance zeolite catalyst for alkylation of benzene with long chain olefin.