Copper-rhodium-magnesium-aluminum four-component catalyst for preparing 1,2-propylene glycol by adding hydrogen directly to biodiesel-based crude glycerine and preparation method of 1,2-propylene glycol

Abstract

The invention discloses a Cu-Rh-Mg-Al four-component catalyst for preparing 1,2-propylene glycol by directly adding hydrogen with biodiesel-based crude glycerine as a raw material and a preparation method of the 1,2-propylene glycol. The Cu-Rh-Mg-Al four-component catalyst can be synthesized by one step by a coprecipitation method and can be directly used in the preparation of the 1,2-propylene glycol by adding hydrogen with the biodiesel-based crude glycerine as the raw material after being roasted and reduced; and the efficient synthesis of the 1,2-propylene glycol is realized under the mild and green conditions by using the catalyst and the biodiesel-based crude glycerine as the raw materials. In the process of directly adding hydrogen in a 75 percent glycerine water solution at 180 DEG C and 2.0 MPa hydrogen pressure, the highest yield of the 1,2-propylene glycol after reacted for 10 hours can reach 71.2 percent; and under the same reaction conditions, the yield of the 1,2-propylene glycol by using a 75 percent glycerine-ethanol solution can reach 89.2 percent.

Description

technical field [0001] The invention relates to a catalyst for directly hydrogenating biodiesel-based crude glycerin to prepare 1,2-propanediol and a preparation method thereof. More specifically, it is a copper-rhodium-magnesium-aluminum four-component catalyst for preparing 1,2-propanediol through direct hydrogenation of biodiesel-based crude glycerin and a preparation method thereof. Background technique [0002] 1,2-Propylene glycol (1,2-PDO for short) is a colorless, viscous, stable hygroscopic liquid, almost odorless and tasteless, and flammable. Melting point -60°C, boiling point 187.3°C, relative density 1.036 (25 / 4°C), miscible with water, ethanol and various organic solvents, easily oxidized above 150°C. [0003] 1,2-Propanediol is an important raw material of unsaturated polyester, epoxy resin and polyurethane resin. This kind of unsaturated polyester is widely used in surface coatings and reinforced plastics. 1,2-Propanediol is highly viscous, hygroscopic and n...

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Problems solved by technology

[0012] Chinese patent CN200610105255.X discloses a CuO-SiO 2 Catalyst, the catalyst is used for hydrogenation of glycerol at 140-200 degrees and 40-100 atmospheres. This catalyst has a better effect on hydrogenation of glycerol in methanol solution and has high activity in continuous fixed-bed reactors, but methanol solvent Expensive, flammable, toxic

[0017] Chinese patents CN200810120727.8 and CN200810120728.2 disclose a reaction process for preparing propylene glycol by hydrogenation of biodiesel-based crude glycerol under the action of a metal-solid base dual-functional catalyst. Although a batch-type autoclave reaction process is adopted, the reaction time is long Up to 20 hours, the reaction temperature is as high as 180-260 degrees

[0018] Chinese patent CN200810228573.4 discloses a catalyst prepared with Ag and Cu as active components, but the reaction temperature in the examples is above 200 degrees, the yield of propylene glycol is low, and the highest yield of propylene glycol is only 47.5%

Although there are also patent applications using batch-type autoclave reactors, the temperature of the reaction is high or high-purity glycerin is used as a raw material, because the preparation of high-concentration glycerin requires high energy consumption, and at the same time, due to biodiesel-based crude glycerin It also contains a certain amount of residual catalyst (mainly NaOH, Ca(OH) 2 , NaH 2 PO 4 etc.), the refining process of glycerol is complex and costly, so the direct hydrogenation of crude glycerol containing a certain amount of aqueous solution to prepare 1,2-propanediol has higher practical value and potential industrialization

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