Modulation Of ZSM-5 Molecular Sieve And Its Application In MTG

Methanol to gasoline(MTG)is an important part of achieving clean and efficient use of coal.It is in line with China's energy diversification strategy and is a research hotspot.Based on this,the paper carried out the modulation of ZSM-5 molecular sieve and its application in MTG,which has academic significance and application value.Firstly,five kinds of molecular sieves ZSM-5 with a ratio of Si to Al of 40,80,120,160 and 200 were synthesized by hydrothermal method,and they were characterized and evaluated separately.The results show that the five kinds of silica-alumina ratio molecular sieves are typical MFI structures;the low silicon-to-aluminum ratio(Si/Al-40)molecular sieves have stronger acidity,higher acid content and specific surface area up to 380 m2/g.In the catalytic MTG reaction,the methanol conversion was 100%and the C5+ selectivity was 60%.Next,the molecular sieve ZSM-5 of Si/Al-40 was subjected to phosphorus modification,alkali modification and hydrothermal treatment,and its effect on the physicochemical properties of the molecular sieve was characterized.The reaction behavior of MTG was also evaluated.The results show that the phosphorus modification can achieve the simultaneous regulation of the strong acid strength and acid amount of the molecular sieve.A suitable concentration of alkali-modified molecular sieve increased the mesopores of the molecular sieve,and the MTG reaction was catalyzed by AT-0.3(0.3 M NaOH treated ZSM-5),the methanol conversion rate was 100%,and the gasoline component selectivity was above 60%.The suitable hydrothermal treatment temperature can simultaneously regulate the acidity and strong acidity of the catalyst,but the excessive hydrothermal treatment temperature can significantly reduce the activity of the catalyst.Among them,HT-400(HZSM-5 hydrothermally treated at 400 ?)has higher methanol conversion rate,the C5+ selectivity was around 65%.Finally,the Si/Al-40 molecular sieve was amplified synthesis by a 50-fold crystallizer.The results show that the physicochemical properties of the synthesized molecular sieves are similar to those in the laboratory,and the catalytic effects are comparable.The optimized modification and catalytic conditions are as follows:Si/Al-40 molecular sieves were sequentially tuned to pore structure by 0.3 M NaOH,ammonium exchange and hydrothermal treatment at 400 ? and formed Under normal pressure,WHSV=1.0 h-1,350?380?,the methanol conversion was 100%,the gasoline component selectivity was above 60%,and the single-pass catalytic life was about 280 h.