Analysis of key problems in HPPO production process
01
Hydrogen peroxide manufacturing
Most of the hydrogen peroxide used in the HPPO production process is produced by the anthraquinone method, and the concentration and quality of hydrogen peroxide directly affect the progress of the epoxidation reaction. In order to obtain the best conversion rate of HPPO production process, the Evonik process chooses 70% concentration of hydrogen peroxide, and the hydrogen peroxide should meet the following requirements: First, the mass ratio of alkali metals should meet the corresponding requirements. Secondly, the mass content of anions should reach the corresponding standard. Finally, the mass ratio of amines with PK b less than 4.5 is less than 10 PPM. In the HPPO production process, ensuring the quality of hydrogen peroxide is an important key content, and the selection of hydrogen peroxide based on catalyst performance is a very important link.
02
Reactor combination
In the HPPO production process, most of the selected reactors are fixed-bed shell-and-tube, and cooling units need to be configured to achieve reasonable control of the reaction temperature. Among them, the BASF process adopts the method of connecting two reaction devices in series, and installs purification equipment in the reactor to achieve the purpose of separating propylene oxide. The remaining hydrogen peroxide can be connected in series with the second reactor, and can consume all of hydrogen peroxide. The reactors of the Evonik process are operated in parallel, but the residence time of the mixture in the output of this reactor is too long, and the unreacted hydrogen peroxide can only be removed in the subsequent hydrogenation unit, resulting in the increase of by-products. Dow Company adds hydrogen peroxide, methanol, propylene and o-chlorodibenzene to the reactor. Because the boiling points of PO and the solvent are different, the propylene oxide at the production site can be distributed to it, and the proportion in the mixture can be Reached about 70%. In the existing technology, the propylene oxide in the high-temperature rectification tower reacts with water to form a by-product, and the reactor will separate the water in time during the discharge process, thereby reducing the need for the separation process. It reduces the cost of consumption and reduces the probability of by-products, which is also the main development direction of this process technology in the future.

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