Method for preparing biodiesel by zirconia solid base catalyst

Abstract

The invention discloses a method for preparing biodiesel by a zirconia solid base catalyst. The biodiesel is obtained by taking vegetable oil as a raw material to react with methanol or ethanol, adding the catalyst into the obtained product, and performing the transesterification. The solid base catalyst is rare earth metal oxide which takes zirconia as a carrier to support rare earth oxide, or takes zirconia supported rare earth metal oxide as the carrier and supports potassium fluoride. The preparation of the biodiesel by adopting the zirconia solid base catalyst as a catalyst for alcohol-grease exchange has high catalytic activity, has the conversion rate which is more than 94 percent, and has convenient post-treatment; the catalyst can be repeatedly used for multiple times after the recovery; and a product, namely the biodiesel and a byproduct glycerol are neutral, do not need to wash, and cannot produce industrial wastewater.

Description

technical field [0001] The invention relates to a method for preparing biodiesel, in particular to a zirconia solid alkali catalyst used for preparing biodiesel. Background technique [0002] Using oil crops such as soybeans and rapeseeds, fruits of oil trees such as oil palm and pistachio chinensis, engineering microalgae and other oil-bearing aquatic plants, animal fats, waste cooking oil, etc. as raw materials, the organic Fatty acid methyl ester or ethyl ester fuel is biodiesel, and the by-product is glycerin. The traditional process for preparing biodiesel uses homogeneous catalysts, such as sodium hydroxide, sodium methoxide, sodium carbonate, potassium hydroxide and potassium carbonate, etc., and the dosage accounts for about 1% of the oil weight. The reaction temperature is not high, generally methanol Boiling point temperature, fast reaction speed, high conversion rate (above 95%). However, the separation of the catalyst in the homogeneous method is difficult, and...

AI Technical Summary

Problems solved by technology

The traditional process for preparing biodiesel uses homogeneous catalysts, such as sodium hydroxide, sodium methoxide, sodium carbonate, potassium hydroxide and potassium carbonate, etc., and the dosage accounts for about 1% of the oil weight. The reaction temperature is not high, generally methanol Boiling point temperature, fast reaction speed, high conversion rate (above 95%)

However, the separation of the catalyst in the homogeneous method is difficult, and a large amount of industrial wastewater will be generated in the post-treatment process, causing environmental pollution.

Using enzymes as catalysts can be recycled, and the reactants and products in the catalyst have a large mass transfer rate, but during the reaction, if the process and parameters are improperly grasped, it is easy to cause enzyme "poisoning" and affect the catalytic effect

In addition, the application of enzyme-catalyzed transesterification is limited due to high enzyme price, long reaction time and low reaction yield.

The supercritical non-catalytic transesterification reaction is carried out, the reaction time is short, the conversion rate is high, and the post-treatment is simple, but the molar ratio of alcohol to oil is high, and the reaction temperature and pressure exceed the critical temperature and critical pressure of methanol, which requires high equipment requirements.