Effect Of Ni State In The SBA-15 On CH₄-CO₂ Reforming Catalytic Performance

Carbon dioxide Reforming of Methane（CRM）shows a growing interest from both industrial and environmental viewpoint.From an environmental viewpoint,CO₂and CH₄ are undesirable greenhouse gases and both are consumed by this reaction.From an energy viewpoint,one potential advantage of CRM is that it is possible to produce syngas with H₂/CO approximately 1,which can be applied to methanol and F-T synthesis without further regulation.The major drawback of this reaction,however,is the rapid deactivation caused by carbon deposition via the Boudouard reaction and CH₄ decomposition.In view of this problem,we adopted simple impregnation method to prepare Ni/SBA-15 catalyst with high dispersion and stability.The main works and results are as follows:A series of Ni/SBA-15（AM）catalysts were prepared by chelating ligand assisted impregnation method.The results showed that the chelating ligand played a positive promoting role for CH₄ dry reforming with CO₂ over Ni/SBA-15.The electron-pair donor atoms and the high viscosity of chelating agent could inhibit the aggregation of nickel species and contribute to the well-dispersed Ni particles with size of<6 nm.Compared to the Ni/SBA-15（CM）prepared by conventional impregnation,all the Ni/SBA-15（AM）exhibited superior catalytic performance,especially the catalyst assisted by ethylenediamine possessed stable activity and the least amount of carbon deposition.Ni/SBA-15 catalyst was prepared by thermal induction method and presented excellent catalytic performance CO₂ reforming of methane.It was amazing that the thermal induction process led to the rebuilding of Ni particles on SBA-15,and the agglomerated Ni particles（550Ni/SBA-15,prepared by impregnation method）become evenly distributed（900Ni/SBA-15,modified with thermal induction）.Meanwhile,particles with the size of 2-3 nm（the main catalytic centers）were widely observed on T-Ni/SBA-15.H₂-TPR also revealed that the main reduction temperature increased from 431°C（550Ni/SBA-15）to 642°C（900Ni/SBA-15）,indicating the thermal induction strengthened the metal-support interaction.During CO₂/CH₄reforming lifetime test at 750°C for 50 h,the conversion of CH₄ maintained at around85%and that of CO₂ was 90%over the T-Ni/SBA-15.Additionally,the carbon deposition was effectively hindered as confirmed by TG.