p-Xylene selectivity enhancement in methanol toluene alkylation by separation of catalysis function and shape-selective function

•Separated catalysis function and shape-selective function for methanol toluene alkylation.•Covering of external surface Al sites with Silicate-1 is less efficient when applied to low Si/Al ratio HZSM-5 samples.•High p-xylene selectivity obtained without affecting catalyst reactivity.•A part of m-xylene and o-xylene molecules comes from HZSM-5 pore directly rather than through secondary isomerization.•HZSM-5@S-1 showed no deactivation in the 130hours lifetime test.