Ionothermal Synthesis Of Heteroatom Aluminumphosphate Molecular Sieves And The Catalytic Application On Benzylation

Hierarchical structured aluminumphosphate molecular sieve has been ionothermally synthesized by microwave irradiation in eutectic mixture solvent, and its crystallization process was made at ambient pressure or exposure containers, it is also favour for adopts in situ characterization methods to study the synthesis mechanism of molecular sieve. Organic cations and inorganic species in eutectic system has played a strong interactions for template effect and for solvent and template agent at the same time, without extra add mesoporous template to synthesis hierarchical structured aluminumphosphate molecular sieve. Hierarchical structured SAPO-5molecular sieve was ionothermally synthesized by microwave irradiation using a mixture solution of succinic acid, choline chloride and tetraethyl ammonium bromide as solvent and template under ambient pressure. The effects of the ratio of P2O5/Al2O3and HF/Al2O3, silicon source and crystallization time on the structure of SAPO-5molecular sieve were systematically investigated. The resulting SAPO-5molecular sieve was characterized by XRD, SEM, TEM, N2physical adsorption-desorption and29Si MAS-NMR techniques, respectively. The analysis results obtained from SEM, TEM and N2physical adsorption-desorption indicate that intra-crystalline and inter-crystalline mesopores coexist within the SAPO-5molecular crystals, while29Si MAS-NMR shows that the incorporation of Si in the sample follows SMIII mechanism.Diphenylmethane mainly adopts benzene and benzyl chloride by benzylation synthesis, but due to benzene don’t has electron-donating group, so the reaction is a challenge in the field of synthetic chemistry, iron-based catalyst has high benzylation catalytic performance could solve this problem effectively. This article adopts the hydrothermal method and impregnation method for Fe/AlPO-5molecular sieve synthesis, two kinds of microporous molecular sieve catalytic properties in the alkylation reaction of benzene with benzyl chloride was systematically investigated, deeply discusses the influence rule of the Fe containing in catalyst, Fe species distribution, reaction temperature and benzene/benzyl chloride mole ratio in reaction system on the conversion of benzyl chloride and diphenylmethane yield. The following conclusion is obtained by experiment:the Fe species on the catalyst is closely related to the reactivity of FeAlPO-5molecular sieve, increased Fe containing in catalyst can contribute to the further conversion of benzyl chloride, it may be due to the cooperative catalysis of Fe3+in the [FeO4]-Coordination complex together with Fe2O3nanopaiticles and increased the activity center, and promoted benzene to react with benzyl chloride to diphenylmethane, but Fe3+in the [FeO4]-on Fe/AlPO-5molecular sieve by impregnation synthesis could not react with Tetrahedron coordination Fe3+form Cooperative catalysis contribution more to this benzylation.