Method for separating by-products in process for preparing methyl formate by carbonylation of methanol

Abstract

The invention discloses a method for separating by-products in a process for preparing methyl formate by methanol carbonylation, and the method comprises the following steps: after methanol carbonylation reaction, a product enters a gas-liquid separation tank (5) to flash out CO gas, and a liquid phase is subjected to methanol-methyl ester separation through a methyl ester rectifying tower (7); part of kettle liquid at the bottom (7) of the methyl ester rectifying tower is cooled and then returns to the dry methanol storage tank (1) to be recycled, the other part of kettle liquid enters the film evaporator (10) to be concentrated and separated, part of solid phase and methanol enter the residual liquid crystallization kettle (11) in a self-flowing mode to be cooled and then fed into the horizontal screw centrifuge (12) to be subjected to solid-liquid separation, and solid salt is discharged; the liquid enters the disc centrifuge (13) to be separated again, the liquid passing through the disc centrifuge (13) returns to the dry methanol storage tank (1) to be recycled, and solid-liquid salt is discharged from a slag discharge port of the disc centrifuge (13). The method is good in desalting effect, high in automation degree, low in methanol loss and low in environmental protection risk.

Description

technical field [0001] The method belongs to the technical field of chemical industry, and specifically relates to a method for separating by-products in the process of producing methyl formate through methanol carbonylation. Background technique [0002] At present, in industrial production, there are two main processes for the production of methyl formate: one is methanol dehydrogenation, and the other is methanol carbonylation. The raw material gas of methanol carbonylation process gas contains a small amount of CO 2 and H 2 O, in actual production, CO 2 、H 2 O will have a side reaction with the catalyst sodium methoxide to produce salt by-products such as sodium formate, sodium carbonate, and sodium hydroxide. If these by-products are not removed in time, they will accumulate in the circulating methanol, and will block when the salt content reaches a certain concentration. The raw material gas enters the nozzle, resulting in a high pressure difference in the reacto...

AI Technical Summary

Problems solved by technology

The raw material gas of methanol carbonylation process gas contains a small amount of CO 2 and H 2 O, in actual production, CO 2 、H 2 O will have a side reaction with the catalyst sodium methoxide to produce salt by-products such as sodium formate, sodium carbonate, and sodium hydroxide. If these by-products are not removed in time, they will accumulate in the circulating methanol, and will block when the salt content reaches a certain concentration. The raw material gas enters the nozzle, resulting in a high pressure difference in the reactor, and the device is forced to stop and manually clean the nozzle

At present, the desalination methods of production enterprises mainly use bag filters as tools, adopt intermittent and discontinuous methods, and separate methods with low automation, which lead to high labor costs and large environmental pollution.

Although the continuous desalting method of the disc centrifuge is more automated than the bag filter, due to the characteristics of high salt content and large salt particles in the feed, the butterfly centrifuge can only separate small particles of salt. The separation effect is poor, and the separation of by-products is difficult, which leads to frequent maintenance of equipment, and the separated by-products also contain about 70% methanol (about 50Kg / h), which requires manual recovery and treatment, resulting in a large loss of methanol, which is safe and environmentally friendly. Risks and other issues restrict the stable, long-term, full and optimal operation of the device

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