Preparation And Application Of Aromatization Catalysts

Aromatization is an important process in naphtha upgrading and high value-added utilization of methanol.Generally,the low-carbon alkane aromatization can be promoted using ZSM-5 zeolite catalyst.A strategy for improving the activity and stability of catalysts was studied in this paper based on the problem of the obvious cracking reaction and carbon deposition caused by the strong acidic of HZSM-5 zeolite catalyst.The composition of the catalysts and the preparation process were optimized by treating with hydrothermal,adding SAPO-11 zeolite instead of HZSM-5 zeolite,modifying with different metal and nonmetal,changing the content of HZSM-5 zeolite.The catalytic performance of the as-prepared catalysts was evaluated on a fixed bed reactor using Qingdao Refinery straight-run naphtha as raw material.The optimized catalyst exhibits excellent catalytic performance in naphtha aromatization process and MTA reaction.As the research object of naphtha aromatization,The hydrothermal treatment of the Zn/HZSM-5-Al₂O₃ catalysts was performed at different temperature.The results show that the stability of the catalyst and the liquid yield of the products were improved after hydrothermal treatment.When the hydrothermal treatment temperature is 450?,the aromatization performance is best.In addition,the increasing rate of aromatics increased significantly after the introduction of SAPO-11 into Zn/HZSM-5 catalyst.The Zn-Ni/HZSM-5 catalyst exhibits the highest aromatization activity activity and stability compared with HZSM-5,Zn/HZSM-5,Zn-P/HZSM-5 and Zn-Ni/HZSM-5 catalysts.In addition,it is better than industrial catalysts.The effect of the content of HZSM-5 zeolite on catalytic performance was studied.The results show that the the activity of aromatization can be improved significantly with the increase of the content of HZSM-5,but the liquid yield decreased sharply.According to the above results,the optimized 450-Zn-Ni/Z?the content of HZSM-5zeolite is 60%?catalyst exhibits excellent aromatization activity and stability.The effect of reaction temperature on the aromatization performance of the as-prepared 450-Zn-Ni/Z catalyst was further studied.It can be found that the aromatization activity and stability can be increased with the increase of reaction temperature,however,the liquid yield was decreased.Overall,The better reaction temperature is between 400? and 440? for the naphtha aromatization process.Additionally,the as-prepared 450-Zn-Ni/Z catalyst also exhibits high methanol conversion and the selectivity of benzene,methylbenzene and dimethylbenzene?BTX>45%?for methanol aromatization.