A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, Recommanded Product: 1941-30-6, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 1941-30-6, Name is Tetrapropylammonium bromide, molecular formula is C12H28BrN. In a Article, authors is Burkett, Sandra L.，once mentioned of 1941-30-6
Mechanism of Structure Direction in the Synthesis of Si-ZSM-5: An Investigation by Intermolecular 1H-29Si MAS NMR
The role of tetrapropylammonium (TPA) ions as a structure-directing agent in the synthesis of pure-silica ZSM-5 (Si-ZSM-5) is investigated by solid-state NMR.It has previously been proposed that the mechanism of structure direction involves preorganization of silicate species around the TPA ions with subsequent assembly of these inorganic-organic composite structures to yield crystalline Si-ZSM-5 with occluded TPA molecules.However, such structures have not been directly observed.Here, 1H-29Si CP MAS NMR is performed between the protons of TPA and the silicon atoms of the zeolite framework precursors in a deuterated synthesis medium to probe the relationship between the organic and inorganic components.The 1H-29Si CP MAS NMR results indicate that short-range intermolecular interactions, i.e., on the order of van der Waals interactions (ca. 3.3 Angstroem for H to Si), are established during the heating of the zeolite synthesis gel prior to the development of long-range order indicative of the ZSM-5 structure. 1H-13C CP MAS NMR spectra suggest that the TPA molecules within the composite inorganic-organic structures adopt a conformation similar to that which they have in the zeolite product.These results thus provide the first direct evidence for the existence of preorganized inorganic-organic composite structures during the synthesis of Si-ZSM-5.They also demonstrate the types of noncovalent intermolecular interactions that are relevant to the existence of an organic structure-directing effect.A modified mechanism of structure direction and crystal growth of Si-ZSM-5 is proposed.
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Reference：
Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI