摘要/Abstract

环己醇是一种重要的化工中间原料，目前工业上主要是以ZSM-5分子筛作为催化剂，通过环己烯水合反应一步法制备.钛硅分子筛TS-1是工业环己酮液相氨肟化过程中的高效催化剂，其失活后显示出典型Brønsted酸性质，基于此，本工作发展了失活TS-1作为催化剂催化环己烯水合反应的方法，详细考察了反应时间、反应温度、催化剂含量及环己烯和水的质量比等参数对反应的影响.研究表明，失活TS-1是高效催化剂，在优化的反应条件下可得到11.0%的环己醇收率和99.8%的环己醇选择性，显示出高活性、高选择性和高稳定性的特点.通过酸洗改性与K⁺交换实验以及结合UV-Vis（固体紫外漫反射可见光谱）、FT-IR（傅里叶变换红外光谱）、²⁹Si MAS NMR（固体魔角硅核磁）和NH₃-TPD（氨气程序升温-脱附）等表征技术，进一步研究发现，失活TS-1中含有两种Brønsted酸中心，而催化环己烯水合反应的高效活性中心为与钛羟基相邻的硅羟基（Si-OH（Ti））.该Brønsted酸中心的结构完全不同于ZSM-5分子筛中的骨架桥式Brønsted酸中心（Si-（OH）-Al），且表现出相对较弱的酸强度特征，因而促进了环己烯水合反应中生成环己醇的主反应路径，抑制了环己烯异构化的副反应路径，表现出高环己醇选择性的特性.失活TS-1废催化剂特殊Brønsted酸中心的发现与应用为废催化剂固废资源的资源化利用提供了新思路.
关键词: 失活TS-1, 环己醇, 环己烯, 水合反应, Brønsted酸中心
Cyclohexanol is an important chemical intermediate material. At present, ZSM-5 is mainly used as a catalyst in the industry to produce cyclohexanol by one-step hydration of cyclohexene. Its core is the development of high-performance catalysts. TS-1 is a high efficient catalyst for industrial liquid-phase ammoniation of cyclohexanone, which shows a typical Brønsted acidity after deactivation. Based on this, we applied the deactivated TS-1 as catalyst for cyclohexene hydration reaction, and investigated systematically the effects of reaction time, reaction temperature, catalyst dosage and mass ratio of water to oil on the hydration reaction of cyclohexene. The results showed that the deactivated TS-1 could offer a high catalytic performance with 11.0% yield and 99.8% selectivity towards cyclohexanol under the optimized reaction conditions, which indicated that the deactivated TS-1 is a high-performance catalyst and possesses the characteristics of high activity, high selectivity and high stability. Combined with nitric acid treating modification, potassium ion exchange experiment and the characterization techniques such as UV-Vis (UV-visible spectroscopy), FT-IR (Fourier transform infrared spectrometer), ²⁹Si MAS NMR (²⁹Si magic angle solid nuclear magnetic resonance), and NH₃-TPD (temperature-programmed desorption of ammonia), it was found that the deactivated TS-1 possesses two kinds of Brønsted acid sites, whereas its real active center for the hydration reaction of cyclohexene is silanol group adjacent to titanium hydroxyl group (Si-OH(Ti)). The structure of this Brønsted acid site is completely different from the skeleton bridge Brønsted acid site (Si-(OH)-Al) of ZSM-5 zeolite, meanwhile shows relatively weak acid strength. The unique acid property of Si-OH(Ti) could promote the main reaction path of cyclohexanol formation and inhibit the side reaction path of cyclohexene isomerization in cyclohexene hydration reaction, which determined its characteristic of high cyclohexanol selectivity. The discovery and application of the special Brønsted acid site of the deactivated TS-1 waste catalyst can provide a new idea for resource utilization of solid waste resources of spent catalyst.
Key words: deactivated TS-1, cyclohexanol, cyclohexene, hydration reaction, Brønsted acid site


PDF全文下载地址:

点我下载PDF