Developments Of Catalytic Performance For Non-oxidative Methane Dehydroaromatization Over Mo/HZSM-5 Catalyst

Methane can convert directly into more valuable liquid aromatics products with high selectivity under the absence of O2 condition,and the by-product-hydrogen.This is not only beneficial to the use of a lot of cheap resources methane, also is expected to replace the oil resources of benzene preparation process. In this paper, HZSM-5 molecular sieve as the support, Mo、Co、Zn、Cu、Mg、Cr modified HZSM-5 catalysts were prepared by incipient wetness impregnation. Their catalytic performance was tested in a fixed-bed reactor,especially, the effect of reaction temperature, space velocity, SiO2/Al2P3, the content of the active component, reaction time on the catalytic performance over Co modified Mo/HZSM-5 catalyst was studied.Also the regeneration of Mo/HZSM-5 catalyst was investigated.The effect of regeneration medium, space velocity of regeneration medium, regeneration time on the catalytic performance was studied under 800℃.The catalysts were characterized by N2 adsorption, XRD, NH3-TPD, FT-IR, TG-DTA.It was found that Mo modified HZSM-5 catalyst has certain catalytic activity,but with poor stability.The maximum conversion of methane is 11%,the yield of aromatics products can reach 6.5% at 700℃. The maximum conversion of methane is 23%,the yield of aromatics products can reach 14% at 800℃,but the activity of the catalyst decreased with increasing the temperature.The addition of Co to Mo/HZSM-5 promoted the stability and the life of the catalysts (the formation of benzene increased about lnmol-C/g/s-3 nmol-C/g/s, benzene yield increased about 2%-5%), The synergetic effect was significantly with increasing the temperature.The regeneration of Mo/HZSM-5 was discussed, the formation concentration of benzene decreased 18% in 2h through 4minCH4-10minH2, while formation concentration of benzene decreased to zero without regeneration.Therefore, the regeneration mode can significantly reduce the carbon deposition on the catalysts.After appropriate amount of Mo-modified or Co-modified, the ratio of weak acid amount and strong acid amount was moderate, iron compounds that uniform dispersion in the surface of the molecular sieve, improve the activity of catalyst.