Process for the preparation of 2-ethylhexanal

Abstract

The invention relates to the process for the preparation of 2-ethylhexanal which is characterized in that, low palladium-content catalyst is employed to reduce the production cost, a two-section lower-charged bubble type heat-insulated fixed bed reactor is employed to reduce the circulating amount and improve the selectivity. The method can appreciably reduce the carbon forming amount for the catalyst.

Description

technical field [0001] The invention relates to a process for preparing 2-ethylhexanal from 2-ethylhexenal (octenal) by selective hydrogenation. Background technique [0002] 2-Ethylhexanal is an intermediate for the synthesis of 2-ethylhexanoic acid and spices. For the preparation of 2-ethylhexanal, Pd / SiO was invented in DEA1941634 2 Catalyst, using 2-ethylhexenal as raw material, using the hydrogenation product as a solvent cycle, the disadvantages of this process are high pressure, small feed space velocity of raw materials, low conversion rate and selectivity, and the yield of the target product low rate. [0003] Use nickel catalyst in U.S.Pat.No.4,018,831, do solvent with octanol, reaction conversion rate is 88%, selectivity is 94%, the shortcoming of this technology is to select octanol as solvent for use, there is the problem of separation, and its hydrogenation The conversion and selectivity are relatively low. [0004] Pd / γ-Al was invente...

AI Technical Summary

Problems solved by technology

[0002] 2-Ethylhexanal is an intermediate for the synthesis of 2-ethylhexanoic acid and spices. For the preparation of 2-ethylhexanal, Pd / SiO was invented in DEA1941634 2 Catalyst, using 2-ethylhexenal as raw material, using the hydrogenation product as a solvent cycle, the disadvantages of this process are high pressure, small feed space velocity of raw materials, low conversion rate and selectivity, and the yield of the target product low rate

[0003] Use nickel catalyst in U.S.Pat.No.4,018,831, do solvent with octanol, reaction conversion rate is 88%, selectivity is 94%, the shortcoming of this technology is to select octanol as solvent for use, there is the problem of separation, and its hydrogenation The conversion rate and selectivity are relatively low

[0004] Pd / γ-Al was invented in U.S.Pat.No.5,756,856 2 o 3 As a catalyst, its palladium content is 0.5%, the palladium content of the catalyst used is high, and the cost of the catalyst is high

The invention adopts a process of two-stage hydrogenation and hydrogenation product circulation. The conversion rate and selectivity of this process are high, but its high reaction temperature is likely to cause carbon formation on the surface of the catalyst.

The reactor type is a trickle bed reactor fed from the top, and the trickle bed reactor is easy to channel flow, requires a high circulation ratio, and increases back mixing and power consumption

[0005] The Soviet patent proposed the use of Pd / γ-Al 2 o 3 As catalyzer, do solvent with isobutyl butyrate, experiment under the condition that hydrogen ratio is 30, the selectivity of this method and conversion rate are higher, but the hydrogen ratio of this method is high, and use isobutyl butyrate as Solvent, because the boiling points of isobutyl butyrate and isooctylal are relatively close, it is difficult to separate

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