CO₂ Reforming Of Methane Over Fe-Ni Bimetallic Catalyst For Syngas Production

CO₂ reforming of methane?CRM?can convert the greenhouse gases CH₄ and CO₂ into syngas,which not only can alleviate the energy crisis and the greenhouse effect,improve energy utilization,but also the resultant syngas with a molar ratio of CO/H₂ being about 1 can be directly used for the production of some chemical products.Therefore,CRM is widely studied.Ni-based catalysts are often investigated due to its low cost and high catalytic activity.However,the deactivation of Ni-based catalysts caused by coke deposit and the Ni sintering at high temperature restricts their industrial application.Therefore,the effect of preparation method,promoter loading and preparation conditions on the catalytic performance were studied to develop the Ni-based catalysts with high activity and resistance of carbon deposition.Ni-based composite metal catalysts with good catalytic performance were used to investigate the effects of reaction temperature,volumetric hourly space velocity?VHSV?and different gas ratios on the performance of autothermal reforming of methane.Given the Ni-Mg-Al hydrotalcite with strong alkalinity,good dispersibility of active component and Fe₂O₃ with great redox characteristics,NiMgAl hydrotalcite and Fe were used as precursor and promoter to prepare Fe-Ni bimetallic catalysts?Fe-Ni/LDO?catalysts by different impregnation methods.The prepared Fe-Ni/LDO catalysts were evaluated for CH₄-CO₂ reforming with a small amount of oxygen.The results show that the catalyst prepared by microwave-assisted impregnation method has better catalytic performance.A series of Fe-Ni/LDO composite metal catalysts were prepared by microwave-assisted impregnation method and applied to CO₂ reforming of methane.The effects of Fe loading,microwave impregnation temperature and heating power on the structure and properties of the catalyst were investigated.The characterization results show that Fe was successfully incorporated into the hydrotalcite structure and the Fe-Ni/LDO composite catalysts.The formation of Ni-Fe alloy enhances the interaction between the active component Ni and the support,and decreases the Ni particle size.The CO₂ reforming of methane was carried out over the resultant catalysts under the conditions of 750°C,48,000 mL·h^-1·g^-1_cat and CH₄/CO₂/O₂/N₂=1/1/0.1/1.9.The Fe-Ni/LDO catalysts improve catalytic activity,stability,and show good resistance of carbon deposition compared with the Ni/LDO catalyst without Fe.When the Fe loading,microwave impregnation temperature and heating power is 1 wt.%,60 ^oC,and 800 W,respectively,the prepared catalyst exhibited the highest catalyst activity and maintained its activity for 80 h during the reaction.CH₄ and CO₂ conversions remained at73%after 80 h,the least carbon amount is deposited.The reaction temperature and space velocity had a certain influence on the CRM perpormance.High temperature was favorable for the reaction,and the conversions of CH₄and CO₂ were improved.However,the catalytic activity decreased as the space velocity increased.The effect of oxygen on catalyst performance was further investigated at 750 ^oC and 48,000 mL·h^-1·g^-1_cat.The oxygen addition in the CH₄-CO₂ reforming?i.e.,autothermal reforming of methane?can effectively eliminate the carbon deposit,and the different H₂/CO ratio can be obtained by adjusting the feed gas composition CH₄/O₂.The activity during autothermal reforming of methane was higher than that of CRM.With the increase of oxygen content,the conversion of CH₄ increased and the conversion of CO₂ decreased.After 80 h of reaction,no obvious carbon deposit was detected on the catalyst surface.