摘要
合成气制低碳醇涉及C1化学的两个重要问题,C—O键的留存和断裂,在这个过程中碱性位点被证明有利于抑制烃类生成。采用水热法和沉淀法分别制备了具有不同碱量和碱性强度的单斜晶相氧化锆(m-ZrO_(2))和四方晶相氧化锆(t-ZrO_(2)),以其为载体,通过浸渍法制备了Cu/m-ZrO_(2)和Cu/t-ZrO_(2)催化剂,探讨了锆基催化剂中碱性位点对合成气制低碳醇性能的影响。采用X射线衍射(XRD)、N_(2)吸脱附、H_(2)程序升温还原(H_(2)-TPR)、CO_(2)程序升温脱附(CO_(2)-TPD)和FT-IR表征分析了催化剂的构效关系。结果表明,催化剂表面中强和强碱位点有利于总醇产率的提高。单斜晶相ZrO_(2)(m-ZrO_(2))和其催化剂(Cu/m-ZrO_(2))表面总碱量高、弱碱位点占比高、与弱碱位点相关的羟基浓度高,醇产物中甲醇占比高。四方晶相ZrO_(2)(t-ZrO_(2))和其催化剂(Cu/t-ZrO_(2))表面强碱和中强碱位点占比及密度高、O_(2)-浓度高,醇产物中C_(2+)醇占比高。研究明晰了催化剂表面碱性位性质、数量、强度与产物醇分布的关系。
Synthesis of higher alcohols from syngas involves two important issues in C1 chemistry, the retention and breaking of C—O bond, in which the basic sites has been shown to be beneficial to inhibiting hydrocarbon generation. In this paper, monoclinic zirconia(m-ZrO_(2)) and tetragonal zirconia(t-ZrO_(2)) with different basic quantity and basic strength were prepared by hydrothermal method and precipitation method, respectively, and the corresponding catalysts Cu/m-ZrO_(2)and Cu/t-ZrO_(2)were prepared by impregnation method. The effect of basic sites over these catalysts on the catalytic performance of higher alcohols synthesis from syngas was investigated. XRD, N_(2)desorption, H_(2)temperature programmed reduction(H_(2)-TPR), FT-IR, and CO_(2)temperature programmed desorption(CO_(2)-TPD) were used to discuss the structural-activity relationship of the catalysts. The results show that the medium and strong basic sites on the catalysts are beneficial to the improvement of total alcohol yield. Monoclinic ZrO_(2)(m-ZrO_(2)) and its catalyst(Cu/m-ZrO_(2)) possess a high surface total alkali quantity, a high proportion of weak basic sites, and a high concentration of hydroxyl groups related to weak base sites, which is considered to be conducive to methanol production. Tetragonal ZrO_(2)(t-ZrO_(2)) and its catalyst(Cu/t-ZrO_(2)) possess a high proportion and density of medium and strong basic sites, and a high O_(2)-concentration, which is considered to be conducive to C_(2+)alcohol formation. The relationship between the properties, quantity, and strength of base sites on the catalysts and the distribution of alcohols was clarified.
作者
张鸽
李林姝
黄伟
ZHANG Ge;LI Linshu;HUANG Wei(State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology,Taiyuan 030024,China)
出处
《太原理工大学学报》
CAS
北大核心
2023年第1期24-31,共8页
Journal of Taiyuan University of Technology
基金
国家自然科学基金资助项目(2100000292)。
