Resumo

LARA PRADO, Ronald M et al. Synthesis of ZSM -5 zeolite using Diatomite as precursor; its application in the Methanol to hydrocarbons process (mth). Rev. Bol. Quim [online]. 2019, vol.36, n.5, pp.198-209. ISSN 0250-5460.

Abstract Zeolite H-ZSM-5 is widely applied in the petrochemical industry, such as the synthetic process of methanol to hydrocarbons (methanol to hydrocarbons MTH). ZSM-5 zeolite is currently obtained through reagents and expensive processes, being available only a few cheaper alternative routes. In the present investigation, zeolite H-ZSM-5 was obtained from natural diatomite, then characterized, and finally tested in the synthetic MTH process. The natural diatomite was treated with sulfuric acid to perform hydrothermal synthesis with tetrapropyl ammonium hydroxide (TPA-OH). As a result, the H-ZSM-5 zeolite obtained had a Si / Al molar ratio of 23, it exhibited high thermal stability and showed Lowry-Brönsted and Lewis acid sites. The application of this zeolite in the MTH reaction showed a methanol conversion of 88%. The products were: dimethyl ether (DME) in 40%, olefins (mostly ethylene and propylene) in 40% and others in 20%. The reaction conditions were: 300 ° C, 1.2L_metanol/g_cath at atmospheric pressure (0.65 bar). The selectivity of the products can be modified in such a way that DME can be obtained preferentially, up to> 93%, by changing the operating conditions (temperature and space velocity). The use of natural diatomite as a starting material for the preparation of the zeolite H-ZSM-5 represents an attractive route and deserves further investigation for its application and development.

Palavras-chave : Methanol to hydrocarbons; Dimethyl ether; Olefins; Diatomite; H-ZSM-5..

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