Research On Dry Reforming Of Methane To Synthesis Gas Catalyzed By Encapsulated Ni-Based Catalysts

Dry reforming of methane（DRM）to synthesis gas is a promising technology that simultaneously converts CH₄ and CO₂ into a low H₂/CO molar ratio syngas,which can not only effectively alleviate the pressure of global warming,but also helps to reduce over-dependence on fossil energy by using the resulting syngas as a sustainable energy alternative to fossil energy.The transition metal Ni has been widely adopted as the main active component of catalysts for dry reforming of methane to synthesis gas reaction due to its strong ability to activate CH₄ and break C-H bonds,in addition to being abundant and inexpensive.However,Ni-based catalysts are susceptible to face the difficult problems of deactivation caused by carbon deposition and sintering of active metal components under high temperature reforming conditions.Aiming at the above-mentioned difficult problems,this paper prepared encapsulated Ni-based catalyst for catalytic dry reforming of methane to synthesis gas reaction and performed deactivation analysis of spent catalysts.The main research elements and conclusions are briefly described as follows:（1）A series of encapsulated Ni-based catalysts（xNi@S-1,x=5,7,10 wt%）were prepared by the one-pot hydrothermal method.The effects of support structure,catalyst preparation method and Ni content on the physical and chemical properties and catalytic dry reforming of methane to synthesis gas reaction performance of the prepared encapsulated Ni-based catalysts and the reference catalysts were compared and analyzed based on the activity test and characterization results.The results showed that xNi@S-1 catalyst activity showed a volcanic trend with increasing Ni content,with the7Ni@S-1 catalyst exhibiting the highest CH₄ and CO₂ conversions and H₂/CO molar ratio（60.1%,94.3%and 0.94）due to its excellent hierarchical characteristics and reduction properties and unique CO₂ adsorption activation ability.（2）On the basis of the above research,the encapsulated 7Ni@S-1 catalyst was modified by doping with noble metals to further enhance its catalytic activity for dry reforming of methane to syngas reaction.It was found that Pt Ni@S-1 catalyst exhibited the best performance in catalytic dry reforming of methane to synthesis gas,which could be attributed to the fact that the doping of noble metal Pt made the pore size distribution of the catalyst more concentrated,the specific surface area significantly increased and hierarchical properties distinctly improved,resulting in facilitating the dispersion and anchoring of the active metal species and mass transfer during the reaction;meanwhile the formation of alloy enhanced the ability of Ni to activate the C-H bond of methane,thus promoting the efficient conversion of CH₄.（3）In order to investigate the effects of support structure,catalyst preparation method and Ni content,as well as the modification of doped noble metals on the catalytic stability,anti-carbon deposition and anti-sintering of encapsulated Ni-based catalysts,stability testing of prepared encapsulated Ni-based catalysts was carried out and characterized spent catalysts.The results showed that the support structure,catalyst preparation method and Ni content combined to affect all aspects of the catalyst properties and catalytic stability,and that the catalytic stability,anti-carbon deposition and anti-sintering performance of the noble metal modified encapsulated catalysts were influenced by factors such as the degree of alloying and active metal encapsulation.Figure 39 Table 12 Reference 137...