SU487052A1 - The method of producing methyl chloride - Google Patents

Description

one

This invention relates to a process for the production of methyl chloride, which finds use as a solvent and intermediate for the industry of organic synthesis.

A known method for producing methyl chloride by reacting hydrogen chloride and methanol in the gas phase in the presence of a catalyst, for example, zinc chloride deposited on activated carbon.

The disadvantages of this method are the difficulty of processing abgas hydrogen chloride: it is pre-absorbed from the gases with water and then stripped to obtain dry hydrogen chloride. The process of stripping hydrogen chloride from hydrochloric acid is inefficient and complicated. Therefore, synthetic chloride is most often used to obtain methyl chloride, i.e., scarce chlorine is consumed.

Thus, the difficulties associated with using abgas hydrogen chloride to produce chlorine-free methyl by a known method limit the raw material base for hydrogen chloride and thereby significantly complicate the process design.

In order to improve the technological process, it is proposed to use hydrogen chloride in the form of 35-58%,

preferably 39-46% solution in methanol.

When carrying out the synthesis of methyl chloride according to the proposed method, a solution of hydrogen chloride in methanol is subjected to evaporation. The resulting vapors, consisting of hydrogen chloride and methanol, are sent to the methyl chloride synthesis reactor; : molar ratio in pairs PS1: SPZON 1.1 -1.2: 1, necessary for the synthesis of methyl chloride, regulate the amount of solution to be evaporated. The bottoms resulting from the partial evaporation of a solution of hydrogen chloride in Methanol are diluted with methanol to the volume of the initial solution, saturated with abgas hydrogen chloride and returned to the residue. At the same time, the reaction water and impurities associated with abgas hydrogen chloride accumulate in the bottom residue. After repeated use, the bottom residue is withdrawn from the process cycle and methanol is disposed of from it, for example, by distillation.

Example 1. A 45-47% solution of hydrogen chloride in methanol is continuously fed to an evaporator, where the solution is evaporated so that the distillation residue is 30 vol. % of the amount of the original solution. The remaining bottoms are continuously withdrawn from the evaporator. The resulting pairs containing 1,1 -

1.2 mol of hydrogen chloride per 1 mol of methanol, after heating to 130 ° C, are sent to a contact apparatus that is filled with cathadizator, chloride, deposited on activated carbon, and methyl chloride is synthesized at 160-180 ° C. After condensation of the reaction water from the reaction gas, absorption of excess hydrogen chloride, purification of dimethyl ether and sulfuric acid, and drying, methyl chloride is obtained with a concentration not lower than 99.9%. Exit 97%. The bottom residue is diluted with methanol, saturated with abgas hydrogen chloride and returned to the flask. After its LO-115-fold use, neutralization, methanol is reclaimed from it by the method of rectification and the residue is discharged into the sewer system.

Example 2. A 39-41% solution of hydrogen chloride in methanol is subjected to continuous partial evaporation as described in Example 1, with the difference that in this case the amount of the "slaughter residue is 50 vol. % of initial volume. The resulting vapors contain 1.1-1.2 mol of hydrogen chloride per 1 mol of methanol. Methyl chloride is synthesized according to Example I. Methyl chloride is obtained with a concentration of at least 99.9%. Yield 96%. With bottoms arrive as in example 1.

Subject invention

A method of producing chlorine-free methyl by reacting hydrogen chloride with methanol in the gas phase in the presence of a catalyst, for example zinc chloride, deposited on activated carbon, followed by isolating the target product by the known methods, with the aim of improving technological process, use hydrogen chloride in the form of 35-68%, preferably 39-46%, solution in methanol.