Comparative Analysis of the Effect of Different Templates on SAPO-34 in MTO Reaction
کد مقاله : 1061-INZC6
نویسندگان:
مرضیه حمیدزاده *، مریم السادات رحیمی فرد، پویا اسدی پور
شرکت پژوهش و فناوری پتروشیمی
چکیده مقاله:
SAPO-34 molecular sieves were synthesized using morpholine (Mor), triethylamine (TEA) or diethylamine(DEA) as templates, with Al2O3: SiO2: P2O5: 3Template: 50H2O ratios. According to the SEM and the N2 adsorption–desorption of the SAPO-34 produced by TEA template exhibited a larger surface area and a smaller crystal size than those produced by DEA or MOR templates. A high activity and selectivity to olefins (C2= + C3=) were obtained from the catalyst synthesized with the TEA template. At the reaction temperature of 425ͦC, the methanol conversion approached 99% and the ethylene–propylene selectivity and the lifetime of the catalyst produced by TEA, DEA and MOR templates reached maximums of 84%, 81.2, 81.4% and 304, 269 and 200 min, respectively. The catalyst was produced with MOR reached to maximum activity very slower than the other catalysts. Two NH3 desorption peaks on SAPO-34 catalysts can be observed, centered around about 139-156ͦC and 367 -370ͤC, representing low temperature desorption at the weak acidic sites. Compared with conventional SAPO-34 , the strong acid desorption peak shifted to a low temperature and only weak acid sites were observed. The results show the catalyst was synthesized with Pseudo-boehmite, silicilic acid, phosphoric acid and TEA as precursors have an economic chance for commercialize. The incorporation degree in SAPO-34-MOR is larger than that in SAPO-34-TEA and SAPO-34-DEA, but this parameter in surface of SAPO-34-DEA is obviously smaller than the others catalysts. These results are supported by NH3 desorption from weak acid sites in lower temperature in SAPO-34 DEA.
کلیدواژه ها:
SAPO-34; Template; catalytic properties;
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