Key issues in HPPO production process
03
Auxiliary and Solvent Requirements
In the HPPO production process, methanol is selected as the solvent, and recycled methanol and a part of fresh methanol are used in the reactor. If there is too much water in the methanol solvent, the selectivity of propylene oxide will decrease, and the decomposition rate of hydrogen peroxide will also increase. Therefore, it is necessary to reduce the water in the methanol solvent by efficient distillation. By adopting double-column rectification to reduce energy consumption and effectively increase the content of methanol, in industrial installations, special attention should be paid to the water content in circulating methanol, for the relationship between propylene oxide and production efficiency and the energy consumed in the rectification process An effective balance between them to obtain the optimum moisture content. In the HPPO production process, liquid ammonia is generally used as an auxiliary agent, and the selectivity of the catalyst is controlled by adjusting the feed amount of liquid ammonia. However, if the amount added is too large, the catalyst will be deactivated. In the process of industrial production, a balance should be made between reactivity and selectivity, so as to maintain the optimal amount of liquid ammonia added.
04
PO purification
The main purpose of the HPPO production process is to produce PO at a qualified cost. The separation of by-products in the finished product is similar. Add alkali before feeding and add desalted water in the purification tower to remove by-products and promote Separation between propylene oxide and methanol. my country currently adopts two-tower rectification and single-tower purification, which include stripping, extraction and rectification respectively. There are many different processes for PO purification. my country will fully consider the influence of DMM when purifying PO. In BASF technology, a methanol loop is used to achieve the purpose of removing DMM. In this process, attention should be paid to PO The finished product is affected by the alkalinity, and the reasonable choice and reasonable addition of liquid nitrogen and hydrazine hydrate can effectively control the alkalinity.
05
Control of Catalyst Activity
A key issue of HPPO technology is the selection of catalyst and the control of catalyst activity. The factors affecting catalyst activity are mainly the following aspects:
01 ▏The water content in methanol will affect the activity of the epoxidation reaction, so the water content in the circulating methanol must be strictly controlled.
02 ▏Research proves that the addition of a small amount of liquid ammonia can improve the selectivity of the catalyst to the product, but excessive addition will reduce the selectivity, so the amount of liquid ammonia added should be strictly controlled.
03 ▏The presence of phosphate, etc. will block the catalyst gap in the reactor tube and affect the distribution of materials, so it is very important to remove phosphate in the raw material.
04 ▏The organic amines in the solvent will cause irreversible deactivation of the catalyst, and should be strictly monitored.
All in all, in the HPPO engineering production process, the points that need to be paid attention to are mainly concentrated in the process mechanism, reaction conditions, production process and other links. In these links and processes, the catalyst is indispensable, and the choice of catalyst solvent is directly related to The final rendering of the HPPO production process. In addition, in the HPPO production process, the selection of raw materials, the speed of the reactor, the separation of the mixture, the purification of the product, etc. are also very important. These factors have had a non-negligible impact on the HPPO process. Among all the current production methods of propylene oxide, the HPPO production process is more outstanding in energy saving, environmental protection, high efficiency and other aspects, and will have greater development in the future, and will move towards a more mature, safe and environmentally friendly direction development

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