Acrylaldehyde preparation method by glycerin dehydration under inert gas dilution

Abstract

The invention relates to an acrylaldehyde preparation method by glycerin dehydration under inert gas dilution, particularly an acrylaldehyde preparation method by the glycerin which is the byproduct of the preparation of biodiesel. Under inert gas atmosphere, alumina and acid zeolite are taken as catalyst; under the conditions that the reaction temperature is 200-500 DEG C, the reaction pressure is 0.001-3.0MPa and the liquid airspeed is 0.1-100.0h<-1>, the glycerin is directly dehydrated to generate acrylaldehyde and byproduct hydroxyacetone. The technique is characterized in that dehydration reaction is carried out under inert gas atmosphere, thus the activity, selectivity and stability of the reaction are high, especially high concentration glycerin can be taken as raw material and is high in selectivity and stability; thus reducing waste liquid treatment capacity of post treatment and greatly reducing energy consumption and production cost.

Description

technical field [0001] The invention relates to a method for preparing acrolein by dehydrating glycerin under the dilution of an inert gas. Specifically, inert gas is passed into the reaction system to dilute the raw material so that it is in an inert gas atmosphere, and alumina and acidic zeolite are used as catalysts. Reaction temperature 220~450℃, reaction pressure 0.001~2.0MPa and liquid space velocity 0.5~50.0h -1 Under certain conditions, the method of directly dehydrating glycerol to acrolein. Background technique [0002] Acrolein is mainly prepared by the selective oxidation of propylene, but the depletion of petroleum resources and the rise in international oil prices have caused the price of raw material propylene to remain high, increasing the production cost of acrolein and its downstream product acrylic acid. Biodiesel, as a green alternative energy, has become the current development trend. It is a green and environmentally friendly chemical process route to...

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Problems solved by technology

But the acrolein yield of these techniques is generally low, and stability is low, and yield declines rapidly with the reaction time, more importantly, these techniques all adopt the aqueous glycerol solution of lower concentration to be raw material (the glycerol content in the general raw material is only 10-25wt%), because the water content in the raw material is too large, it causes high energy consumption in industrial production, which in turn leads to high cost

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