MTO performance over seed-assisted SAPO-34 zeolites synthesized by reducing template consumption

摘要

SAPO-34 samples were prepared via a seeding-induced method with a considerable reduction of template concentration. The resultant SAPO-34 zeolites were investigated by XRD, FESEM, EDS, N2adsorption, and NH3-TPD analyses. The samples represent different catalytic activity in the MTO process due to their differences in the physic-chemical properties, including crystallite/particle sizes, surface area, acid strength and concentration. Pure SAPO-34 was obtained with a 60% reduction of organic template for the first time. However, due to the increase of particle sizes, it did not show the desired catalytic performance. An excellent catalytic performance was achieved for the seeding-induced catalyst prepared by a 40% reduction of template content according to its appropriate high acidity and relatively large surface area. This sample exhibited 91.8% selectivity toward light olefins and about 330?min of lifetime, which were 14.4% higher in term of selectivity and more than twice lifetime than the unseeded sample. This substantial achievement was obtained under the industrial feed conditions (72%wt methanol in water) and provided a cost-effective and environmentally friendly route for preparing promising MTO catalyst with notably decreased template dosage.