Nano ZSM-5 molecular sieve based catalyst and preparation and use methods

Abstract

The invention discloses a nano ZSM-5 molecular sieve based catalyst and preparation and use methods. The molecular sieve catalyst consists of molecular sieves and metal components, wherein the molecular sieves are nano ZSM-5 molecular sieves with a short b-axis, a medium high silica-alumina ratio, less strong acid, high Lewis acid content, and resistance to hydrothermal deactivation. The preparation method is as follows: mixing a silicon source, an aluminum source, a template agent, a structure promoter, an additive and alkali with water, and stirring to prepare a precursor solution, then crystallizing, separating solid from liquid, and calcinating to obtain molecular sieve raw powder; mixing the molecular sieve raw powder with an ammonium salt solution, stirring, filtering, mixing with the ammonium salt solution for several times, stirring, filtering, and calcinating to obtain hydrogen-type ZSM-5 molecular sieves; mixing with the metal precursor solution, drying and calcinating to obtain the aromatization catalyst. The use method is as follows: transforming oxy-compound raw materials to aromatic hydrocarbon through the catalyst under the reaction conditions. The nano ZSM-5 molecular sieve based catalyst has the characteristics of being high in aromatics yield (reaching up to 99%) and long in service life (the catalyst is alive after 300 hours, and the aromatics selectivity reaches up to 70% after the catalyst is subjected to hydrothermal aging at 760 DEG C for 4 hours).

Description

technical field [0001] The invention belongs to the technical field of preparation of aromatic hydrocarbons, and in particular relates to a nanometer ZSM-5 molecular sieve catalyst and its preparation and use methods. Background technique [0002] Aromatics such as benzene, toluene, p-xylene, trimethylbenzene, and tetramethylbenzene are important chemical raw materials, and their consumption is second only to ethylene and propylene. Among them, trimethylbenzene can prepare various dye intermediates such as trimellitic acid and benzoic anhydride, and can also be used to produce antioxidants, polyester resin curing agents, stabilizers, alkyd resin plasticizers, etc. Mesitylene is a good It is used as a developer for silicone photosensitive sheets in the electronics industry. Pyromellitic dianhydride obtained by oxidation of durene and diamine compounds can be polymerized to produce polyimide engineering plastics. At the same time, p-xylene (PX) can be produced by the disprop...

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Problems solved by technology

[0006] The acidic strength and acid site distribution of ZSM-5 will also have a huge impact on its catalytic performance. Studies have shown that lower Si / Al can improve the selectivity of aromatics, and at the same time generate a large amount of light hydrocarbons, and the selectivity of aromatics cannot exceed 80%. , strong acids are prone to hydrogen transfer to light hydrocarbons