Application Of Supported Nickel-based Catalyst Modification Process In High Temperature Catalysis

The methane dry gas reforming reaction in high temperature catalysis can simultaneously use methane and carbon dioxide in the greenhouse gas to convert into synthesis gas.On the one hand,it can reduce environmental pollution and on the other hand,it can produce high valueadded products,which has attracted much attention.Nickel-based catalysts have been widely studied due to their low price,simple preparation,and high activity.The disadvantage is that nickel-based catalysts have poor stability at high temperatures and are prone to carbon deposition and deactivation.In this paper,the traditional Ni/Al2O3 catalyst was modified to improve the high temperature stability of the nickel-based catalyst.The main method of modification is to introduce inorganic oxide modified layers Si O2 and Ti O2.The active molecules contact and react with the reactants through the pores of the inorganic oxide,which largely prevents carbon deposition on the surface of Ni particles.Secondly,the inorganic oxide plays a role of fixing and dispersing on the surface of the catalyst,so that the Ni particles are not easily agglomerated and deactivated.On the one hand,we use tetraethylorthosilicate(TEOS)as the silicon source,and adopt an acid-catalyzed method to modify the Si O2 layer and introduce the surface of the Ni/Al2O3 catalyst to prepare the Ni/Al2O3@Si O2 catalyst.The Ni/Al2O3@Si O2 catalyst was applied to the methane dry gas reforming reaction.The evaluation results showed that the conversion rate of CH4 and CO2 was increased by about 4% compared with the Ni/Al2O3 catalyst.The Ni/Al2O3@Si O2 catalyst was characterized by XRD,BET,TEM,elemental analysis,pyridine infrared,etc.The results showed that the modified catalyst had an increased specific surface area and introduced B acid sites compared to the Ni/Al2O3 catalyst.The catalyst is not prone to agglomeration,the Ni particles are more dispersed,and the ability to resist carbon deposition is strong.On the other hand,we use tetraethyl titanate as the titanium source,and use hydrochloric acid as an anti-hydrolysis agent to modify the Ti O2 layer and introduce the Ni/Al2O3 catalyst surface to prepare the Ni/Al2O3@Ti O2 catalyst.The Ni/Al2O3@Ti O2 catalyst was applied to the methane dry gas reforming reaction.The evaluation results showed that the catalyst activity decreased as the number of modifications increased.The Ni/Al2O3@Ti O2 catalyst was characterized by XRD,BET,elemental analysis,pyridine infrared,etc.The results showed that the modified catalyst had a lower specific surface area than the Ni/Al2O3 catalyst,and the Ti O2 layer covered part of the Ni particles,resulting in a decrease in the activity of the catalyst.