Hierarchical porous titanium-silicon molecular sieve as well as preparation method thereof and olefin epoxidation method

Abstract

The invention relates to a hierarchical porous titanium-silicon molecular sieve as well as a preparation method thereof and an olefin epoxidation method. The hierarchical porous titanium-silicon molecular sieve has a grain size of 600-700 nm, has relative crystallinity of 55-64%, has a specific surface area of 660-725 m<2> / g, has a total pore volume of 0.55-0.7 cm<3> / g, and has a mesoporous volumeof 0.3-0.5 cm<3> / g; the volumes of pores with the pore diameters of 0.5-2 nm of the hierarchical porous titanium-silicon molecular sieve account for 15-36% of the total pore volume, the volumes of pores with the pore diameters of 2-4 nm account for 1-25% of the total pore volume, and the volumes of the pores with the pore diameters of 4-16 nm account for 20-45% of the total pore volume, and the volumes of the pores with the pore diameters greater than 16 nm account for 20% or lower of the total pore volume. The hierarchical porous titanium-silicon molecular sieve disclosed by the invention isgreater in mesoporous volume, is higher in proportion of the total pore volume, and can remarkably increase an olefin conversion rate and can improve selectivity of alkyleneoxide while used for olefin oxidization reaction.

Description

technical field [0001] The disclosure relates to a hierarchical porous titanium-silicon molecular sieve, a preparation method thereof, and an olefin epoxidation method. Background technique [0002] Since titanium-silicon molecular sieves were developed in the 1980s, people have successively developed titanium-containing heteroatom molecular sieve TS-1 with MFI structure, heteroatom molecular sieve TS-2 with MEL structure, and Ti-beta with BEA structure. , TS-48 with macroporous structure, MCM-41 with MWW structure and a series of titanium silicon molecular sieves with different skeleton structures. [0003] The excellent catalytic oxidation activity of titanium silicate molecular sieves is based on the Ti in the framework structure 4+ The active center, whose remarkable function is to support the H 2 o 2 The selective oxidation of the organic matter involved has a good effect, and it will not be deeply oxidized, and the product selectivity is high. It has the incomparabl...

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Problems solved by technology

[0006] Although the research on the preparation of hierarchical porous molecular sieves by silanization has been very abundant, only [3-trimethoxysilylpropyl] dimethyl octadecyl ammonium bromide and N-phenyl-3-aminopropyl trimethoxy Two silylating reagents based on silane are used in the synthesis of hierarchically porous titanium-silicon molecular sieves, and the titanium-silicon molecular sieves prepared by direct silanization treatment and precrystallization-silanization treatment have insufficient crystallinity, mesopore and macropore distribution. Low, large molecular sieve crystal grains, low activity, etc.

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