| With the development of economy and society,the consumption of natural resources is accelerating.Therefore,the scientific and efficient utilization of limited resources conforms to the scientific concept of sustainable development.1-buten have a low effective utilization rate in China's petrochemical industry.Most of the 1-butene is burned in liquefied petroleum gas,resulting in waste of resources.Therefore,producted 1,3-butadiene with 1-butene is conducive to the efficient utilization of resources.1,3-butadiene can be used in synthetic rubber,resin and intermediate of various chemical raw materials.In recent years,increased demand for 1,3-butadiene is in short supply.The production of 1,3-butadiene by CO2 oxidation can avoid the safety risk brought by O2 as an oxidant and the excessive oxidation of products.At the same time,the utilization of greenhouse gas CO2 is in line with the concept of green chemistry.Therefore,the production process has good development prospects.In this paper,carbon materials with excellent structure and surface properties were used as catalyst carriers to carry out surface modification and metal additives doping modification,and to synthesize new carbon materials and their applications.The details are as follows:(1)Iron-based catalysts were prepared by using activated carbon as carrier,and the surface groups with content of activated carbon were adjusted by nitric acid oxidation method.It was found that the amount of groups was the largest when the concentration of nitric acid was 5M,and the active carbon maintained its channel structure.Raman showed that there was an interaction between the active component of the catalyst and the carrier.The OCGs,which could provide acid sites on the surface of activated carbon,played an anchoring role for the active components.The performance of catalyst showed that Fe/AC-5M catalyst had the best activity,the conversion of 1-butene was 79%,the selectivity of 1,3-butadiene was 54%,and the BD rate was 1850 gBD/Kgcat/h.(2)The catalyst Fe/AC-5M with the best nitric acid treatment conditions was further doped with V,Cr,K,Li and La metal additives to change the alkaline and electron cloud density of the catalyst.The characterization of XRD,XPS and MES showed that nitric acid modification and doping of metal additives were helpful to reduce the oxidation of Fe.The addition of K,Li and La was helpful to the formation of Fe7C3,and the Fe7C3 is beneficial to the improvement of product selectivity.Meanwhile,the addition of alkali metal can restrain the carbon deposition and improve the stability of catalyst.The catalyst performance showed that KOH-FeVCr/AC-5M had a maximum selectivity of 73%for 1,3-butadiene.The catalyst with the best catalytic performance was selected to explore the reaction condiction,and water vapor was introduced to reduce the generation of carbon deposition and promote the regeneration of the active center of the catalyst.Finally,the optimal air inlet ratio was obtained as 1-butene:CO2:H2O=1:20:10,under which the highest catalyst conversion was 90%and the selectivity was 70%(3)Carbon materials with ordered mesoporous structure was successfully prepared by hard template method and modified with nitrogen.By comparing the amorphous activated carbon supported catalyst Fe/AC,it was found that mesoporous carbon materials with regular structure had better catalytic stability and higher product selectivity,which indicated that the ordered structure of carbon materials was more conducive to the dispersion of active ingredients,thus improving the catalytic activity.Nitrogen doping can form basic groups on the surface of the catalyst and change the electronic flow of the catalyst.The selectivity of Fe/OMC on 1,3-butadiene was 51%. |
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