Production method for synthesizing acetic acid through carbonylation

Abstract

The invention discloses a production method for synthesizing acetic acid through carbonylation. The method comprises the following steps of: synthesizing acetic acid by performing carbonylation on methanol or a derivative of methanol serving as a raw material and liquid reaction composition at the reaction temperature of 170-210 DEG C and under the reaction pressure of 2.0-6.0Mpa; and continuously introducing reducing gas into a flash evaporator or a subsequent pipeline. The liquid reaction combination comprises a rhodium catalyst, a methyl iodide catalyst accelerator, methyl acetate, acetic acid, water, an alkali metal iodized salt, and a variable-valence metal salt serving as a stabilizer as well as promoter. Under the synergic actions of the variable-valence metal salt and the reducing gas, the rhodium catalyst can keep high stability under the condition of low water content, the adverse influence of the iodized salt on the stability of the rhodium catalyst can be lowered, the reaction activity under a low-water condition is increased, the contents of propionic acid serving as a side product and unsaturated compounds are reduced, and acetic acid can be produced at low energy consumption.

Description

technical field [0001] The present invention relates to the production method of acetic acid, be specifically related to a kind of production method of carbonylation synthetic acetic acid, especially relate to a kind of by adding variable price metal salt, and under the condition that reductive gas is continuously introduced into flasher or follow-up pipeline, to maintain The stable performance and reactivity of rhodium catalyst, thereby the method for producing acetic acid with low energy consumption. Background technique [0002] Acetic acid is an environmentally friendly organic acid and an important chemical intermediate and solvent for chemical reactions, from which hundreds of downstream products can be derived, such as vinyl acetate monomer, cellulose acetate, acetic anhydride, acetate, chloroacetic acid, Terephthalic acid, polyvinyl alcohol and metal acetate are widely used in the synthesis of medicine, synthetic fibers, light industry, textiles, leather, pesticides,...

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Problems solved by technology

Patent EP0055618A1 reports that the rhodium catalyst system can promote the reaction under the action of organic iodine such as methyl iodide, and the water content of the reaction system needs to be controlled at 14~15%, so as to maintain the reaction rate and the stability of the rhodium catalyst, thus making the product more stable. The operating energy consumption is greatly increased, and there are many side reactions

Patent US5001259A discloses a method by using soluble alkaline earth metals or alkali metals such as lithium iodide to further promote the carbonylation reaction and stabilize the catalyst, but increases the concentration of unsaturated compounds such as acetaldehyde, which easily leads to permanganate in the product The potassium time is unqualified, and the impurity concentration of the by-product propionic acid is high, resulting in high energy consumption for the separation of propionic acid column

Patent CN1562937A discloses a method for jointly stabilizing and promoting rhodium catalyst by iodine salt and ruthenium salt. The method for salt-stabilized high-concentration rhodium catalyst, the water content is 0.1 ~ 14%, although the lower limit of water content is further reduced, the concentration of ruthenium or tin added in the embodiment is too high, and the mol ratio with rhodium is 5:1- 20:1, and the additive itself of too high concentration volatilizes and precipitates easily, and under low water condition, reactivity reduces, thereby needs to keep higher rhodium concentration; The stability of its rhodium catalyst needs to be further improved

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