Pd-based hierarchical pore mesoporous-microporous TS-1 molecular sieve single crystal catalyst and preparation method thereof

Abstract

The invention discloses a Pd-based hierarchical pore mesopore-micropore TS-1 molecular sieve single crystal catalyst and a preparation method of thereof. The catalyst comprises a molecular sieve single crystal and Pd nanoparticles, the molecular sieve single crystal is an MFI type molecular sieve, is formed by stacking nanoscale small crystal grains, and has micropores and mesopores formed by stacking the nanoscale small crystal grains, and the Pd nanoparticles are uniformly loaded in mesoporous channels. The preparation method comprises the following steps: by taking a silicon dioxide pellet@porous carbon composite material as a hard template, impregnating the hard template with a structure-directing agent precursor solution to obtain a precursor, carrying out crystal transformation on the precursor by utilizing a steam-assisted crystallization method to obtain hierarchical pore TS-1 molecular sieve single crystals, and finally loading Pd by adopting an impregnation method. Pd particles in the catalyst are dispersed in mesoporous gaps stacked by molecular sieve nanocrystals, while micropores of the molecular sieve nanocrystals are completely reserved, the Pd nanoparticles are confined in mesoporous channels, and the Pd nanoparticles with high loading capacity, high dispersity, uniform distribution and small size are obtained.

Description

technical field [0001] The invention belongs to the technical field of synthesis of noble metal catalysts, and in particular relates to a Pd-based hierarchical mesoporous-microporous TS-1 molecular sieve single crystal catalyst and a preparation method thereof. Background technique [0002] The selective oxidation technology using hydrogen peroxide as the oxidant, the by-product is only water, is a green and environmentally friendly catalytic technology, widely used in important industrial production processes such as olefin epoxidation, methane oxidation to methanol and oxidative desulfurization . [0003] The Pd / TS-1 catalyst composed of noble metal Pd and TS-1 (titanium-silicalite-1) molecular sieve is an important bifunctional catalyst in selective oxidation technology. Among them, metal Pd serves as the acidic active site to catalyze H in situ 2 and O 2 Generate H 2 o 2 . And the resulting H 2 o 2 It diffuses to the Ti active site in the TS-1 molecular sieve thr...

AI Technical Summary

Problems solved by technology

However, the Pd nanoparticles located inside the micropores of TS-1 molecular sieve often sacrifice a large number of micropores, which reduces the activity of TS-1 molecular sieve; while the Pd nanoparticles located on the surface of the molecular sieve, because they are not confined by the channels , easy to agglomerate in the process of synthesis and catalysis to form larger Pd particles, which is easy to cause problems such as low catalytic efficiency

Therefore, it is a huge challenge to prepare PS / TS-1 bifunctional catalysts with small Pd particles, uniform distribution and complete micropores of TS-1 molecular sieves.

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