Structure of toluene6.4-ZSM-5 and the toluene disproportionation reaction on ZSM-5.

The structure of a high-loading complex of ZSM-5 with 6.4 toluene molecules per unit cell has been determined by single-crystal X-ray diffraction. At least three kinds of toluene molecules were identified in the unit cell. Two disordered toluene molecules were located at the intersection of the straight and sinusoidal channels, the third in the sinusoidal channel. One (TOL1) of the two toluene orientations at the intersection was similar to that of p-dichlorobenzene at the intersection in high-loaded H-ZSM-5/p-xylene (hereafter 8PARA) and high-loaded H-ZSM-5/p-dichlorobenzene (hereafter 8PDCB) complexes, respectively. The other toluene orientation (TOL2) at the intersection was similar to those of p-xylene or p-dichlorobenzene at the intersection in the low-loaded p-dichlorobenzene complex (hereafter 2.6PDCB). A third toluene orientation (TOL3) existed in the sinusoidal channel; its orientation was similar to those of p-xylene and p-dichlorobenzene in the sinusoidal channels in 8PARA and 8PDCB complexes, respectively. If the occupancy of TOL2 at the intersection increases with temperature, TOL2 will connect with TOL3 in the sinusoidal channel and form the intermediate diphenylmethane.