Preparation of encapsulated α-Fe2O3@SiO2 catalyst and evaluation of its catalytic performance in orthohydrogen-parahydrogen conversion
Orthohydrogen and parahydrogen(hereinafter referred to as"orthohydrogen-parahydrogen")conversion reaction affects the liquefaction process of hydrogen at low temperature and is an important step in the storage and transportation of liquid hydrogen.Traditional iron-based catalysts face problems such as the aggregative growth of active species,the insufficient resistance ability of water and the poor tolerance ability of high temperature.To solve above problems,α-Fe2O3 was encapsulated into amorphous silica with abundant pore structures,and the encapsulated α-Fe2O3@SiO2 catalyst with high catalytic performance in orthohydrogen-parahydrogen conversion was prepared.SE M、XRD and H2-TPR were used to investigate the effects of the encapsulated structure on surface morphologies,crystal structures and reduction abilities of catalysts.The catalytic performances of catalysts were evaluated by test device,and the relationship between the encapsulated structure and catalytic performance was analyzed and summarized.The results show that the encapsulated structure can optimize the pore structure of the catalyst,regulate the electronic property of active sites,improve the structural stability and high temperature tolerance ability of the catalyst,and thereby improve the catalytic performance.When the volume space velocity is 600 min-1,under the action of α-Fe2O3@SiO2 and α-Fe2O3/SiO2(without encapsulation),parahydrogen volume fractions at the outlet of the device are 41.8％and 37.6％,and the orthohydrogen conversion rates are 22.4％and 16.8％,respectively,indicating that encapsulated iron-based catalysts have high potential for application in the field of orthohydrogen-parahydrogen conversion.
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