Preparation of olefin via methanol on SAPO-34 using organic functionalized SAPO-18 as a seed

SAPO-34 with hierarchical porosity has been synthesised by a new synthesis strategy, based on disturbing the growth of the SAPO-34 crystals by functionalization of the milled SAPO-18 seeds with triethyleamine (TEA) and ethylene glycol in order to prohibit their further association and agglomeration.. The crystalline structures of the modified SAPO-34 materials with different concentrations of organo functionalized seeds were certified by X-ray diffraction. The morphology and textural properties of the materials was confirmed by FE-SEM, and Brunauer-Emmett-Teller surface areas. The acidity of the catalyst was studied by NH3 temperature programmed desorption. According to the N2 adsorption-desorption and the FE-SEM of the catalysts produced by maximum amount of modified seed(8%) exhibited smaller and more uniform crystal size(between 200-450nm), a larger surface area ( about 650m2/g) than those produced by lower percent of seed or without modified seed. NH3-TPD analysis indicated partially the increased weak and strong acidity in the catalyst by maximum amount of seed. A high activity and selectivity to light olefins (C2= + C3= +C4=) were obtained from the catalyst synthesized by this new strategy. At the industrial reaction condition in fix bed reactor( temperature and mass ratio water to methanol equal 425C and 1:2.5), the methanol conversion approached 100% and the ethylene–propylene selectivity, light olefins selectivity and the lifetime of the catalyst reached maximums of 82%, 90% and 500 min, respectively.

کلیدواژه ها:

SAPO-34 ، Methanol to olefin ، SAPO-18 seed ، organic functionalized