Heptane Isomerization Properties Of Rare Earth Modified MCM-48 Catalyst

In the petrochemical industry,alkane isomerization as an important means to improve the octane number of gasoline by more and more attention,due to the quality requirements of the human living environment,research and development of high activity and high stability of the isomerizationcatalyst is imperative.Development of a scheme to overcome the traditional molecular sieve catalyst pore narrow serious cracking high catalytic activity of the catalyst become a focus for researchers.MCM-48 mesoporous molecular sieve has a high surface area,uniform pore size to 2.6 nm and pore neat and orderly and into a three-dimensional structure,etc.,provided an opportunity for the preparation of high metal dispersion and material transfer rate of heterogeneous catalysts.We synthesized precursor MCM-48 mesoporous molecular sieve as the carrier of Cerium,introduced by the different methods of mesoporous molecular sieves modified modified mesoporous molecular sieve MCM-48 for the carrier preparedload the nickel catalyst,and this catalyst is used for the isomerization reaction of n-heptane,and investigated its catalytic properties.Detailed discussion of vectors preparation conditions and the conditions of preparation of the catalyst,reducing conditions,a change in reaction conditions heptane isomerization reaction performance.In this paper,the room temperature and hydrothermal crystallization method have synthesized Ce/MCM-48 and Ce-MCM-48 molecular sieve.the cerium content as well as the template dosage synthesis of mesoporous molecular sieve,and the two zeolite as a catalyst for n-heptane isomerization reaction investigated the catalytic performance.Experimental results show that the room temperature prepared Ce/MCM-48 molecular sieve has a characteristic peak of the MCM-48,but the intensity of the diffraction peak,20=4°～5° interval peaks is not obvious,as the content of cerium increase,and even some of the modified sample no longer has the characteristic peaks of the MCM-48.the effect is not obvious reaction for the catalytic isomerization of n-heptane,n-heptane conversion rate of 9%,isoparaffins select resistance of 35%;Prepared by hydrothermal crystallization of Ce-MCM-48 zeolite at 110℃ under crystallization 72h,550℃ calcined Ce-MCM-48 samples(211)diffraction peak of the strongest,and(220)characteristic peaks visible identifiable peaks 20=4°～5° intervals this shows that the modified mesoporous zeolite channels arranged with strong ordering.This molecular sieve as a catalyst for n-heptane the isomerization reaction catalytic performanc results for Ce-MCM-48 of the catalytic activity and selectivity of only 7%and 49%.Modified zeolite as a catalyst,catalytic isomerization reaction of n-heptane,low catalytic activity,it may be because the metal is too low,the present experiment is prepared by impregnation of a series of nickel as the active component catalyst Ni/Ce/MCM-48 and the Ni/Ce-MCM-48 is prepared by impregnation.The effects of different influencing factors for n-heptane isomerization catalytic performance of these two catalysts.It was found that the nickel loading of 2%,and the reduction temperature was 400℃,the reduction time was 5h,reducing hydrogen flow rate 60mL/min,and the reaction temperature was 290℃ when the Ni/Ce-MCM-48 of the catalytic activity and selectivity can be 26%and 75%.