Unraveling the spatial distribution of the acidity of <scp>HZSM</scp> ?5 zeolite on the level of crystal grains

Here we developed a new method to quantitatively characterize the spatial distribution of Brønsted acidity HZSM-5 zeolite on crystal grains level indirectly. The acid sites completely covered or blocked by previous coke deposition were released gradually from outer surface center via shrinking core mode isothermal oxidation with high temperature and low oxygen concentration. was obtained based one-dimensional position coordinate Lrp through building solving an enhanced model. Then characterized n-propylamine temperature-programmed decomposition correlated specific Lrp. results show that density is roughly homogenous while strength heterogeneous within grains. From grains, increase gradually.