Study On Preparation And Properties Of Pillared Mmt Methane Synthesis Catalyst

In the natural gas industry,petroleum and chemical fertilizer industry,the catalyst of methane synthesis is mainly supported Ni-based catalysts.This catalyst exhibits high activity,but it is easy to be worn and loses the active components in the process of reaction,which will decline the life time.So it is important to synthesize a new and high efficiency catalyst.Pillared interlayered clay?PILC?materials is a class of compounds with special structure and function,which has the advantages of simple preparation,low cost,good stability,and high reaction activity.It is a new nano-porous catalytic material with a very broad application prospect.This paper takes the Na-montmorillonite as substrate clay and adopts intercalation and in-situ synthesis method to prepare pillared montmorillonite.Intercalation method is to make use of the character of water-swelling and ion exchange ability of the substrate clay to insert NiAl-LDHs layer cations into the interlayer of Na-montmorillonite,to obtain pillared clay material after dehydration and calination process.The in-situ synthesis method is to mix and stir the Na-montmorillonite suspention liquid with the mixed solution of Ni?NO₃?₂and Al?NO₃?₃,with adjusting the pH through adding alkali liquor,to obtain the pillared clay material after the processes of suction filtration,dehydration and calcination.The layered catalysts prepared by the two methods are characterized and analyzed by the maens of BET,XRD,FT-IR,TG,TPR and SEM.The preliminary performance evaluations for the two catalysts are carried out by simulating a test of coke oven gas to methane.The study of the NiAl-LDHs by urea decomposition method shows that the longer the reaction time,the higher the crystallization degree,the shape of the NiO characteristic peak tends to be sharper after calcination.The NiAl-LDHs with high regularity,good crystallinity and ordered layer structure can be generated after 16 hours'reaction.It has been found that the crosslinking mixing time has a little impact on the eaction as intercalation method is adopted,6 hours is enough.In order to increase the reactivity of methane synthesis of pillared montmorillonite,the Ni/montmorillonite is 5 mmol/g.The crosslinking reaction is most suitable under the conditions of 30?and pH=6.The structure of the pillared products synthesized by in-situ method is different from the one of the intercalation method.The product effect by in-situ method is better at pH=8,the adsorption capacity of CO will be higher after calcinations and reduction at 500?.The catalyst prepared by synthetic product via dehydration,preforming and calcination is characterized and evaluated separately.The catalysts prepared by the two methods have high conversion for CO in a relatively wide range of temperature and the catalytic activity is higher.The catalyst synthesized by intercalation method is more suitable for synthesis reaction of methane in low temperature due to its high conversation of CO and CO₂ under condition of a low temperature.The catalyst synthesized by in-situ synthesis performs better in higher temperature and is more suitable for synthesis reaction of methane in higher temperature.