Microwave Influence on Different M–O Bonds During MFI-Type Heteroatom (M) Zeolite Preparation

A facile and fast microwave-assisted approach without any other pre/post-treatment has been proposed to hydrothermally synthesize six kinds of MFI-type heteroatom (Mn, Ga, Ti, Sn, Cr, Zr) zeolites. By comparing with oven heating mode, it is found that microwave field displays a positive effect on the introduction of partial heteroatoms in the zeolite framework. Moreover, differing from the conventional heating, microwave irradiation displays different influences on the different heteroatom zeolites because different heteroatoms cause different polarities and wave-absorption abilities of M–O bonds under microwave irradiation. Furthermore, this positive effect of microwave is embodied not only on heteroatom zeolite synthesis and heteroatom state in zeolite framework but also the resultant catalytic performance. This finding provides an easy route for the synthesis of novel heteroatom zeolite being difficult to prepare by conventional mode, along with a new direction for the exploration of microwave effect.