摘要
CH_(4)光催化部分氧化为CH_(3)OH、HCHO等产物是一种潜在的低能耗CH_(4)转化路径,该转化路径存在CH_(4)活化难度高和产物选择性低等问题,高性能催化剂的设计和制备对解决这一系列问题至关重要。使用不同Zn前驱体,通过水热法分别制备了具有块状颗粒、纳米花、纳米片和团聚纳米颗粒等不同形貌特征的ZnO-x光催化剂,发现形貌特征对ZnO-x的CH_(4)光催化部分氧化制HCHO性能(简称“CH_(4)光催化氧化性能”)有显著影响。采用CH_(4)光催化氧化性能最好的ZnO-Cl为基底,进一步制备了nAgCl/ZnO-Cl光催化剂(n为AgNO_(3)物质的量分数)。采用X射线衍射、N_(2)吸/脱附和扫描电子显微镜等对光催化剂进行了表征,并研究了nAgCl/ZnO-Cl的CH_(4)光催化氧化性能。结果表明,2.0%AgCl/ZnO-Cl表现出了最优的CH_(4)光催化氧化性能。在5 mg 2.0%AgCl/ZnO-Cl作用下,当反应条件为25℃、0.1 MPa O_(2)、2.9 MPa CH_(4)、75 mLH_(2)O、光照强度450 mW/cm^(2)和光照2 h时,含氧液相产物(CH_(3)OH+CH_(3)OOH+HCHO)总产率达到10409μmol/(g·h),含氧液相产物总选择性为91.4%,其中主产物HCHO产率为6271μmol/(g·h),HCHO选择性为60.2%。自由基捕获实验结果表明,•O_(2)^(-)和空穴是CH_(4)活化为•CH_(3)的关键,并且•O_(2)^(-)与•CH_(3)的相互作用成为了反应的主要路径,该路径得到的初级产物(CH_(3)OOH)能够较为容易的被氧化为HCHO,从而显著提升了nAgCl/ZnO-Cl的HCHO选择性。
The photocatalytic partial oxidation of CH_(4) to CH_(3)OH,HCHO and other products is a potential low-energy CH_(4) conversion path,which has the problems of high activation difficulty of CH_(4) and low product selectivity.The design and preparation of high-performance catalysts are crucial to solve these problems.Based on the hydrothermal method,ZnO-x catalysts with different morphologies including granules,nano-flower,nano-flake and agglomerated nanoparticles were prepared by varying Zn precursors.It is found that the morphologies of ZnO-x has a significant effect on photocatalytic partial oxidation of CH_(4) to HCHO(short for“CH_(4) photocatalytic oxidation performance”).The nAgCl/ZnO-Cl photocatalysts(n is the mole fraction of AgNO_(3))were further prepared by using ZnO-Cl as the substrate with the best CH_(4) photocatalytic oxidation performance.The samples were characterized by X-ray diffraction,N_(2) adsorption/desorption and scanning electron microscopy,etc.The results show that 2.0%AgCl/ZnO-Cl shows the best CH_(4) photocatalytic oxidation performance.Under the action of 5 mg 2.0%AgCl/ZnO-Cl and reaction conditions of temperature of 25℃,O_(2) pressure of 0.1 MPa,CH_(4) pressure of 2.9 MPa,H_(2)O volume of 75 mL,light intensity of 450 mW/cm^(2) and illumination time of 2 h.The total yield of oxygenated liquid products(CH_(3)OH+CH_(3)OOH+HCHO)is 10409μmol/(g·h),and the total selectivity of oxygenated liquid products is 91.4%,and the main product HCHO is 6271μmol/(g·h)with HCHO selectivity of 60.2%.Based on radical trapping experiments,it is found that the formation of-•O_(2) and the holes are the key to the activation of CH_(4) to•CH_(3),and more importantly,interaction of•O_(2)^(-)and•CH_(3) becomes the major reaction path.In such a way,the initial product(CH_(3)OOH)can be further oxidized to HCHO,and thus leading to the promotion of HCHO selectivity of nAgCl/ZnO-Cl.
作者
王迎霄
张春来
郝英东
孙楠楠
魏伟
WANG Yingxiao;ZHANG Chunai;HAO Yingdong;SUN Nannan;WEI Wei(Key Laboratory of Low-Carbon Conversion Science and Engineering,Shanghai Advanced Research Institute,Chinese Academy of Sciences,Shanghai 201210,China;School of Physical Science and Technology,ShanghaiTech University,Shanghai 201210,China;University of Chinese Academy of Sciences,Beijing 100049)
出处
《低碳化学与化工》
CAS
北大核心
2024年第8期46-56,共11页
Low-Carbon Chemistry and Chemical Engineering
基金
国家重点研发计划“战略性科技创新”重点专项(2022YFEO208100)。
