Method for preparing ethylene glycol by ethylene one-step method

Abstract

The invention relates to a method for preparing ethylene glycol by an ethylene one-step method. The method comprises the following steps: preparing ethylene glycol: under an acidic reaction condition, contacting ethylene, hydrogen peroxide and a titanium silicalite molecular sieve in water, and carrying out an oxidation hydration reaction to obtain the ethylene glycol. The acidic reaction condition is provided by a non-zeolite molecular sieve; the non-zeolite molecular sieve includes a homogeneous liquid acid and / or a heterogeneous solid acid. The method is high in effective utilization rate of hydrogen peroxide, and the target product ethylene glycol is high in selectivity and high in concentration.

Description

technical field [0001] The invention belongs to the technical field of ethylene glycol synthesis, and relates to a method for preparing ethylene glycol in one step from ethylene. Background technique [0002] Ethylene glycol (EG) is an important industrial chemical used in the manufacture of polyester resins and fibers (PET), antifreeze, surfactants, and cosmetics. With the widespread use of polyester PET, the demand for ethylene glycol has greatly increased. [0003] The traditional process for producing ethylene glycol is a two-step process, including two steps of ethylene oxidation and ethylene oxide hydration. Under the action of silver catalyst, ethylene and pure oxygen or air undergo epoxidation under high temperature and high pressure (more than 200°C, about 2MPa) to generate ethylene oxide; after separation and purification, ethylene oxide is , under the condition of 1.5-2.5MPa for direct hydration, wherein the molar ratio of water to ethylene oxide is 22, the sele...

AI Technical Summary

Problems solved by technology

In 2016, Zhang Jialin and others published the work of TS-1 catalyzing ethylene one-step direct preparation of ethylene glycol in the Journal of Petroleum (Journal of Petroleum (Petroleum Processing) August 2016, Volume 32, Issue 4), and systematically studied the ratio of titanium to silicon. , the impact of reaction conditions on the reaction, under the best conditions (0.83mol / L of hydrogen peroxide, 60 ℃, 0.5MPa), the effective utilization rate of hydrogen peroxide is 85.63%, and the mass fraction of ethylene glycol is only 4.35%, which is already in the literature. The highest mass fraction of diol is reported, but it is still not as good as the ethylene oxide hydration process, which means that the concentration of the target product ethylene glycol in the process proposed in the literature is too low, there is a large amount of water in the system, and the separation energy consumption is huge

[0005] Chinese patent CN102452900A proposes a method for producing ethylene glycol in one step from ethylene, using a composite catalyst made of titanium-silicon molecular sieve and solid acidic molecular sieve bonded by resin, when the production efficiency is the highest in the examples (40°C, 3MPa, 30% hydrogen peroxide The volume space velocity is 1.0h -1 ), the effective utilization rate of hydrogen peroxide is 61.7%, and the selectivity of ethylene glycol is 73.9%. In the catalyst preparation process, organic substances such as a large amount of halogenated hydrocarbons and benzene compounds need to be used, resulting in large pollution, and the preparation process is relatively long and complex; Chinese patent CN105001058A discloses a method for preparing ethylene glycol by one-step oxidation of ethylene catalyzed by an aluminum-modified titanium-silicon molecular sieve. Under the optimal conditions (40°C, 0.3MPa) in the examples, the effective utilization rate of hydrogen peroxide is 95.1%. The selectivity of diol is 99.3%. The catalyst preparation mainly includes three steps of mixing titanium-silicon molecular sieve and aluminum salt solution, rotary steaming, and high-temperature roasting. The process is long and consumes a lot of energy. At the same time, there is a large amount of Water, aluminum elements on the catalyst are easy to lose; Chinese patent CN102951998B and Chinese patent CN112851477A propose a process for preparing ethylene glycol in one step promoted by organic surfactants. Compared with the excess of ethylene (the molar ratio of ethylene to hydrogen peroxide is 1:1.1-4), the effective utilization rate of hydrogen peroxide is not high, and there is a risk of hydrogen peroxide self-decomposing to generate oxygen and ethylene to explode; Chinese patent CN112642471A discloses A kind of method that tin-doped Ti-MWW solid molecular sieve catalyzes ethylene one-step preparation ethylene glycol, (40 ℃, 2h, 2.5MPa, 0.1g catalyzer, 1.13g30wt% hydrogen peroxide aqueous solution and 10g water), hydrogen peroxide effective utilization rate 85.1%, ethylene glycol yield is 83.2%, can draw the massfraction of ethylene glycol in solution to be 4.6%

Images