A method for preparing biofuel by direct liquefaction of microalgae

Abstract

The invention relates to a method for preparing a bio-oil from microalgae through direct liquidation. The method comprises the following steps of: mixing microalgae with an alcohol-water mixed solution and putting the mixture into a reaction kettle, and heating for reacting, wherein the reaction conditions are as follows: temperature is 260-360 DEG C, and the pressure is 7-22 MPa; the reaction time ranges from 15 to 45 min; the ratio of the microalgae to the alcohol-water mixed solution is 1:(5-20), and the unit of the mixture is g / mL; the volume percentage content of the alcohol in the alcohol-water mixed solution is 20-80%; after the reaction is ended, adding an organic solvent for extracting the reaction liquid, wherein the reaction liquid is divided into an organic solvent phase, an alcohol-water phase and solid residues; after the extraction is finished, separating out the solid residues through suction filtration, and obtaining the organic solvent phase through separation after standing and layering of the liquid phase; removing the organic solvent from the organic solvent phase through reduced pressure distillation, thereby obtaining an oily liquid, namely, the bio-oil product, wherein the conditions of reduced pressure distillation are as follows: the gauge pressure is 0.085-0.095 MPa, and the temperature is 20-40 DEG C. The method provided by the invention is simple in process flow and low in energy consumption; the process of the method is environmentally-friendly.

Description

Technical field [0001] The invention belongs to the technical field of biomass energy, and particularly relates to a method for preparing biofuel by directly liquefying microalgae under sub / supercritical water-alcohol conditions. Background technique [0002] With the rapid development of modern industry and technology, the shortage of fossil resources and the environmental pollution caused by the use of fossil resources have become two major problems restricting the sustainable development of mankind. Biomass energy is renewable and CO-free 2 Net emissions and SO x , NO x The advantages of low emissions have become a new energy source of general concern. At present, how to fully and effectively utilize biomass resources has become the focus of research and attention. At home and abroad, studies on the use of biomass as raw materials to prepare biofuels are mainly based on lignin and cellulose or hemicellulose materials. However, due to the pyrolysis of lignin and cellulose or h...

AI Technical Summary

Problems solved by technology

However, algae hydrothermal liquefaction also has many shortcomings: (1) low oil yield; (2) unsatisfactory bio-oil quality

But this patent has two deficiencies: 1. In addition to lipids, there are a large number of proteins, polysaccharides and other components in microalgae that have not been fully utilized, resulting in a huge waste of resources

2. The process uses liquid sulfuric acid as a catalyst, and the catalyst is not easy to recycle

However, the algae residue liquefaction process described in this patent is carried out under the condition of super / near critical water. Due to the relatively high critical pressure and critical temperature of supercritical water (Tc: 374.15°C and Pc: ​​22.12Mpa), sub / supercritical The liquefaction reaction of microalgae in critical water medium requires high equipment and relatively harsh reaction conditions; at the same time, the liquefaction process of microalgae in sub- / supercritical water has a relatively low oil production rate, and the acid value of the product biofuel Higher lead to its unsatisfactory quality and other shortcomings

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