Synthesis of SAPO-34 catalyst with through varying molar ratios of SiO2/Al2O3 and H2O/Al2O3

  • سال انتشار: 1391
  • محل انتشار: اولین همایش ملی کاتالیستهای صنعتی
  • کد COI اختصاصی: NICATCO01_017
  • زبان مقاله: انگلیسی
  • تعداد مشاهده: 1513
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نویسندگان

kobra rahimi ashtari

Department of Chemical Engineering, Tarbiat Modares University, Tehran, Iran

mehdi sedighi

jafar towfighi

ali mohamadalizadeh

چکیده

Silicoaluminophosphate, SAPO-34, is known as promising molecular sieve, which is widely used in catalysis, separation processes, and is being developed for new applications, especially in the methanol-to-olefin (MTO)process. In order to examine the influence of silicon and water contents on the morphology of SAPO-34 crystal, different SiO2/Al2O3 and H2O/Al2O3 ratios of synthesis gel were prepared hydrothermally at crystallization temperature of 190 oC. The sources of Al, Si, and P were aluminum isopropoxide, silica gel, and phosphoric acid, respectively. The templates used were the mixture of 75 % morpholine and 25 % tetraethyl ammonium hydroxide. The samples were characterized by XRD, FTIR and SEM techniques. XRD showed that the crystallinity of samples increased with SiO2/Al2O3 ratio to a threshold value. However, a reduction in the crytallinity was observed with futher increase of the silicon content of synthesis gels. The sample with the lowest silicon content had impurities of SAPO-5. SEM images showed the sample synthesized by SiO2/Al2O3=0.53 , H2O/Al2O3=60.25 ratios had the smallest crystal size. The FTIR results showed that there was no considerable increase in the concentration of strong acidic hydroxyl groups with increasing of SiO2/Al2O3 ratio.

کلیدواژه ها

Synthesis, SAPO-34, crytallinity, Morphology

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