Preparation Of Modified Vermiculite Ni-based Catalyst And Its Study In Methane Dry Reforming

With the intensification of energy consumption,it is urgent to explore the transformation of new and old energy sources.Using carbon dioxide as a raw material for chemical production can not only curb global climate change issues,but also provide opportunities for exploring the development of new industries.As a way to produce syngas,methane dry reforming can not only convert two kinds of greenhouse gases?CH₄ and CO₂?,but also produce high value syngas?H₂ and CO?.The components of hydrogen or carbon monoxide can also be separately purified for hydrogenation or carbonylation reactions,and a mixture of hydrogen and carbon monoxide can be used to synthesize hydrocarbons by the F-T process.Under the background of economic globalization,the reforming technology provides a new idea for mitigating global warming.However,before the industrialization of DRM,some issues still need to be resolved.DRM is a highly endothermic reaction,which usually requires a very high temperature to make the reaction proceed.It is inevitable that the active metals in the catalyst are easily sintered and agglomerated.In addition,the rapid deactivation of catalyst caused by serious carbon deposition is also the main obstacle to the long-term operation of the reaction.Therefore,designing and developing catalysts with good catalytic performance and high selectivity to DRM is very important for industrial implementation of DRM.?1?Modified vermiculite supported Ni-based catalyst and its performance in methane reforming.Two-dimensional layered porous nanosheets?EXVTM-SiO₂?prepared by“expansion-acidification”modified vermiculite?VTM?were used as supports,and Ni/EXVTM-SiO₂ catalysts with different loadings was prepared by impregnation method for the methane reforming reaction.It was found that that 10%Ni/EXVTM-SiO₂ exhibited good catalytic activity and stability,and the initial conversion rates of CO₂ and CH₄ were 92%and55%,respectively.The main reason is that 10%Ni/EXVTM-SiO₂ catalyst has large specific surface area and good metal dispersion,so that the catalyst has a certain degree of carbon deposition and sintering resistance.?2?Study on transition metal?Co,Cu,Fe?doped Ni/EXVTM-SiO₂ catalyst and its performance in methane reforming.The NiM/EXVTM-SiO₂?M=Co,Cu,Fe?bimetallic catalyst was prepared by the traditional impregnation method and applied to the methane dry reforming reaction.It was found that the NiCu/EXVTM-SiO₂ catalyst had a high catalytic activity and stability,with a CO₂ conversion rate of up to 92%,and its catalytic activity remained relatively stable,which realized the efficient catalytic transformation of CO₂.On the one hand,the reason can be attributed to the fact that the active metal in the NiCu/EXVTM-SiO₂ catalyst has a smaller particle diameter?10.6 nm?and a relatively high metal dispersibility.On the other hand,the Ni-Cu alloy and oxygen vacancy have a significant effect on the adsorption and activation of CO₂ at high temperature.?3?Study on additives?La₂O₃,CeO₂,ZrO₂?modified NiCu/EXVTM-SiO₂ catalyst and its performance in methane reforming.This experiment investigated the effects of La₂O₃,CeO₂and ZrO₂ promoters on the activity of NiCu/EXVTM-SiO₂ catalyst.The study found that the addition of three different metal oxides did not improve the activity of the NiCu/EXVTM-SiO₂catalyst.On the contrary,some Ni active sites were covered by the promoter,which reduced the number of active sites,resulting in its catalytic activity lower than NiCu/EXVTM-SiO₂.However,in X-NiCu/EXVTM-SiO₂,Ce-NiCu/EXVTM-SiO₂ showed relatively high initial catalytic activity,with the initial conversion rate of CH₄ reaching 60.1%and the initial conversion rate of CO₂ reaching 89.1%.This is mainly because the catalyst has a stronger basic site on the surface to facilitate the adsorption of CO₂ molecules,and the smaller metal particle size is also conducive to the cleavage of C-H bonds.