الفهرس | Only 14 pages are availabe for public view |
Abstract The thesis contains five parts, each concerned with a conversion of methanol to dimethyl ether on zeolite cataltst. Part I: In this part, four different zeolite were used to investigate there activity on DME formation (H-ZSM-5, HMOR, H-BETA and H-Y), its found that H-ZSM-5 zeolite catalyst has higher catalytic activity than the other three zeolite catalyst. This order is compatible with the order of acidity of this zeolite that H-ZSM-5 has stronger acidity than the other zeolites. Part II: In this part we studied the effect of Si/Al ratio on HZSM- 5 and H-MOR zeolite catalyst for conversion of methanol to DME, we studied five samples of H-ZSM-5 zeolite possessing five different Si/Al ratios (25, 90, 120, 240 and 400) and three samples of H-MOR zeolite (6.1, 40, 90), increase Si/Al ratio leads to decrease the catalytic activity due to decrease acidity, so HZSM-5(25) and H-MOR(6.1) have highest activity. Part III: In this part the effect of ultrasonic irradiation were studied on zeolite catalysts: 1-Study the factors affecting ultrasonication efficiency were studied on H-MOR catalyst, effect of ultrasonic irradiation time (20, 40, 60, 80, 100 min), effect of type of solvent (methanol, ethanol, propanol , butanol and warer), effect of volume of solvent (5, 7.5, 10 and 12.5 cm3), its found that the best condition to use ultrasonic irradiation is 60 min, 7.5 cm3 methanol. 2- The best condition of ultrasonication was studied on other zeolite catalyst H-BETA, H-Y, H-ZSM-5 with different Si/Al ratio. Ultrasonic increase the catalytic activity of H-BETA and H-ZSM-5 different Si/Al ratio, but result little decrease in the catalytic activity of H-Y zeolite. Part IV: In this part the effect of halogenation (chlorination and fluorination) and effect of ultrasonic on halogenation were studied on zeolite catalysts. 1-H-MOR: Halogenation of H-MOR either by F- or Cl- was found to promote its activity for conversion of methanol due to increasing the acidity. H-MOR (F) > H-MOR (Cl) > H-MOR The fluorinated H-MOR zeolite catalysts are the most active and selective catalysts for conversion of methanol to DME. Ultrasonic irradiation leads to increase the catalytic activity of chlorinated H-MOR, but decrease the activity of fluorinated HMOR. 2-H-ZSM-5(25): Both chlorination and fluorination increase the catalytic activity of H-ZSM-5(25) zeolite but H-ZSM-5(Cl) has higher activity than H-ZSM-5(F), ultrasoniction increase the catalytic activity of chlorinated H-ZSM-5(25), but decrease the activity of fluorinated H-ZSM-5(25). 3- HZSM-5(400): Halogenation increase the activity of HZ (400), fluorinated sample has higher activity than chlorinated one, ultrasonication increase the activity of both chlorinated and fluorinated H-ZSM-5(400) samples. 4- H-Y: Halogenation increases the activity of H-Y zeolite the activities of the current catalysts can be arranged in the order: HY (Cl) > HY (F) > HY Sonication treatment of halogenated H-Y sample HY (Cl) has higher activity than H-Y (Cl), moreover sonicated H-Y (F) has lower activity than HY (F). Part V: The effect of microwave irradiation time (20, 40, 60 and 80 sec) were studied on H-MOR zeolite catalyst , microwave treatment by 20 sec has higher activity than other microwave times, that increase microwave time leads to decrease the catalytic activity of H-MOR catalyst due to increase crystal size and decrease surface area. |