Modified titanium-silicon molecular sieve, modification method and application thereof in propylene epoxidation reaction

Abstract

The invention discloses a modified titanium-silicon molecular sieve, a modification method, and application thereof in propylene epoxidation reaction. The modified titanium-silicon molecular sieve is obtained by the following steps: dissolving barium salt in water to prepare a barium salt aqueous solution, and then adding a strip-shaped titanium-silicon molecular sieve, wherein the weight ratio of the barium salt to the water to the strip-shaped titanium-silicon molecular sieve is (0.001-0.5):(0.1-5):1; and performing impregnation for 1-72h, performing filtration, drying a solid at 80-120 DEG C for 3-5h, and then performing roasting at 500-550 DEG C for 4-12h to obtain the modified titanium-silicon molecular sieve, wherein the strip-shaped titanium-silicon molecular sieve is obtained by mixing titanium-silicon molecular sieve raw powder with sesbania cannabina powder and silica sol uniformly and then performing strip extrusion forming, and the barium salt is barium nitrate, barium acetate or barium chloride. The modified molecular sieve is a strip-shaped titanium-silicon molecular sieve with an MFI structure; and as a catalyst, the modified molecular sieve is applied to a liquid phase propylene epoxidation process. The modification method disclosed by the invention is simple in operation process, and due to a mutual synergistic effect between the barium salt and the titanium-silicon molecular sieve, the modification method, when applied to the propylene epoxidation reaction, can obviously reduce invalid decomposition of hydrogen peroxide as well as effectively improve the effective utilization of hydrogen peroxide and the selectivity of a product namely propylene epoxide.

Description

technical field [0001] The invention relates to a modified titanium-silicon molecular sieve and a modification method thereof, and further relates to the application of the modified molecular sieve in liquid-phase propylene epoxidation reaction, belonging to the technical field of inorganic chemistry. Background technique [0002] In 1983, Taramasso et al. successfully introduced titanium into pure silicalite, and synthesized titanium-silicon molecular sieve TS-1 for the first time. Titanium-silicon molecular sieve TS-1 belongs to the orthorhombic crystal system and has the same MFI topology as ZSM-5 molecular sieve. Due to the introduction of transition metal titanium, TS-1 has a unique catalytic oxidation performance. TS-1 is widely used in catalytic oxidation reactions such as olefin epoxidation, partial oxidation of alkanes, alcohol oxidation, oximation of ketones, hydroxylation of phenol and benzene, etc. [0003] Hydrogen peroxide is a recognized green oxidant, and i...

AI Technical Summary

Problems solved by technology

However, when the above-mentioned modifiers are modified, they are all carried out at 100-240°C in a crystallization kettle, which has certain requirements on the equipment and needs to bear a certain pressure. The processing process is cumbersome and the processing cost is high; For permanent treatment, due to the use of precious metal raw materials, the treatment cost is relatively high; for modification treatment using inorganic acids, the equipment also needs to have certain corrosion resistance, and the discharged wastewater also needs to be neutralized.

And above-mentioned modification method, all is to modify molecular sieve raw powder, the solid-liquid separation after modification (especially to the separation of nanoscale molecular sieve) is very difficult