Synthesis And Catalytic Alkylation Of SAPO-11 Molecular Sieve

SAPO-11 molecular sieves with different Si O2/Al2O3 were successfully synthesized by hydrothermal method and microwave method. Their physicochemical properties were characterized by XRD、SEM、XRF、ICP、XPS、NH3-TPD and Py-IR. The catalytic performance of the samples obtained from different methods was investigated with alkylation of naphthalene with methanol as the probe reaction.In order to choose the appropriate reaction conditions, activation conditions, reaction temperature, reaction pressure and space velocity were investigated with SAPO-11 molecular sieves synthesized by hydrothermal method as catalyst.The results indicated that the optimized conditions were as follows: activation temperature 550℃, activation time 2h, reaction temperature, pressure and space velocity respectively were 420℃, 4.0MPa and 1h-1.Compare acidity and catalytic performance of SAPO-11 obtained from different methods, the results indicated that as Si O2/Al2O3 increasing, the amount of acid sites increased; when samples synthesized by hydrothermal method were chosen as catalysts,conversion of naphthalene, selectivity of 2,6-DMN and 2,6-/2,7-DMN increased. But for catalysts obtained from microwave method, conversion of naphthalene decreased, and selectivity of 2,6-DMN and 2,6-/2,7-DMN increased, then decreased. When ratio of Si O2/Al2O3 was 0.6, better catalytic performance was obtained on SAPO-11 molecular sieves synthesized by microwave method. Naphthalene conversion was 56.2%, the selectivity of 2, 6-DMN is 32.4%, and the ratio of 2, 6- / 2, 7- DMN is 1.93.Mg APO-11 and Co APO-11 molecular sieves were synthesized by hydrothermal method and microwave method, respectively. The structure and acid properties of Me APO-11 molecular sieves were characterized by XRD, UV-Vis, SEM and NH3-TPD. Meanwhile, their catalytic performance of alkylation of naphthalene with methanol was also investigated. The results indicated that synthysis method, heteroatom species and content significantly affect the structure, acidity and catalytic properties.When gel composition was the same, Mg APO-11 molecular sieves synthesized by microwave method shown better catalytic performance. Nap hthalene conversion was 64.7%, the selectivity of 2,6-DMN is 34.1%, the ratio of 2,6- / 2,7- DMN is 2.05.SAPO-11 and Me APO-11(Me=Co, Mg) molecular sieves were successfully synthesized in ethanol-water media. Their structure and acidity of the samples were varied by changing gel compositon and the ratio of ethanol and water in Crystallization media. The results indicated that ethanol-water media facilitated Si, Co and Mg toincorporated the molecular skeleton and formed homogeneous acid sites. catalysts synthesized in ethanol-water media show better catalytic performance. When the ratio of ethanol / water was 10/35, 56.2% of naphthalene conversion, 32.4% of 2,6-DMN selectivity and 1.93 of the ratio of 2,6- / 2,7 – DMN were achieved on Co APO-11 molecular sieves.