A method for producing 2,2'-bipyridine in a membrane reactor

Abstract

The invention discloses a method used for producing 2,2'-dipyridyl using a membrane reactor. The method comprises following steps: pyridine is subjected to preheating gasification, pyridine gas is delivered into a reactor, and is delivered through a catalyst bed layer, so that 2,2'-dipyridyl is obtained under the action of a dehydrogenation catalyst; 2,2'-dipyridyl and a part of unreacted pyridineare collected via condensation using a gas-liquid separator; hydrogen gas obtained via reaction and most unreacted pyridine are delivered into a membrane pipe through a membrane porous material pipeinserted into the catalyst bed layer so as to realize separation from 2,2'-dipyridyl, nitrogen is introduced through the bottom of the membrane pipe for blowing of gas state pyridine and hydrogen, andan obtained mixed gas is discharged through the upper part of the membrane pipe. The method is high in pyridine conversion rate, instant separation of unreacted raw materials and products can be realized, and catalyst service life is prolonged.

Description

technical field [0001] The invention belongs to the fields of fine chemical industry and organic synthesis, and in particular relates to a method for preparing 2,2'-bipyridine in a membrane reactor. Background technique [0002] 2,2'-Bipyridine is an important intermediate in chemical and pharmaceutical synthesis. Due to its unique chelation effect, it can be used as a ligand for metal catalysts, a photosensitizer, and an indicator for detecting metal ions. [0003] There are two main methods suitable for industrialized preparation of 2,2'-bipyridine, one is the Ullmann method (M.Tiecco et al., Communications, 1984, 736-738), using 2-halopyridine as raw material, under the action of catalyst A coupling reaction occurs to generate 2,2'-bipyridine. The advantage of this method is high conversion rate and mild reaction conditions. The disadvantage is that the amount of three wastes is large, and it has been gradually eliminated. Another method is to use pyridine as a raw mater...

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Problems solved by technology

[0003] There are two main methods suitable for industrialized preparation of 2,2'-bipyridine, one is the Ullmann method (M.Tiecco et al., Communications, 1984, 736-738), using 2-halopyridine as raw material, under the action of catalyst A coupling reaction occurs to generate 2,2'-bipyridine. The advantages of this method are high conversion rate and mild reaction conditions. The disadvantage is that the amount of three wastes is large and has been gradually eliminated.

The advantage of this method is high atom utilization rate and environmental protection, but the single conversion rate is low. The patent GB897473 uses Raney nickel to prepare 2,2'-bipyridine in a Soxhlet reactor at normal pressure and 100-120 ° C. The highest The conversion rate is less than 1%; US5416217 uses loaded nickel to prepare 2,2'-bipyridine in a fixed-bed reactor at a temperature of 175-240°C and a pressure of 0.9-1.5Mpa. Although the catalyst life of this method reaches 500h, the conversion rate remains below 1%

The low conversion rate makes the separation of the product 2,2'-bipyridine and the raw material pyridine cumbersome. For example, the separation by rectification requires a lot of energy, and the difficulty of separation also restricts the industrialization of this method.

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