CONTEXT

Continuous energy crises and increasing demand for conventional fuels has resulted in the need for biofuels on a commercial scale. Transesterification of oils to biodiesel is coupled with significant production of a glycerol-rich water (so-called « crude » or « raw » glycerol), as an important side-product of the process. The increasing demand for biodiesel leads to abundant quantities of this glycerol on the market. Therefore, glycerol valorization has much to offer in the cost reduction of biodiesel production.

Etherification constitutes one of the ways of valorization of glycerol for obtaining glycerol ethers, still indicated polyglycerols. The glycerol ethers have various applications according to their preparation and of their structure. The polyglycerols are also primarily intermediaries of synthesis of the esters of polyglycerols.

TECHNICAL DESCRIPTION

The invention describes the use of a solid catalyst to synthesize polyglycerol from glycerol.

This new catalyst is mesoporous, heterogeneous, providing basic active sites due to the presence of alkaline compounds. This etherification could reach a polymerization degree of 4, whereas existing products have got a polymerization degree of 9.

BENEFITS

This process is selective so that a fraction of di to tetraglycerol is obtained with a yield of 95%.

This process doesn’t use any solvent. Indeed the reaction is performed in a reactor where  glycerol  is in contact with the solid catalyst in well chosen conditions (atmospheric pressure and temperature around 200 °C)

INDUSTRIAL APPLICATIONS

Polyglycerol main applications are: lubricant synthesis, replacing petroleum oils in order to use products less polluting and biodegradable, replacing triglycerides in food industry.

The glycerol ethers find also applications like surface-active neutrals, in the depollution of the grounds, the industry of the cosmetic, of pharmacy, in the food industry.

Furthermore polyglycerol with weak polymerisation degree may be interesting in cosmetics and detergent industry as active-surface agents.

DEVELOPMENT STAGE

Have been also investigated :

• the synthesis of polyglycerols esters in similar conditions either in a 2 steps process or in a single step procedure. It was demonstrated that polyglycerol esters could be obtained directly from glycerol and methyl esters over the same catalysts.
• other catalytic materials i.e. with a different porosity in order to get a more important fraction of higher polyglycerols (di to hexaglycerol) in similar conditions.
• the scaling up of the preparation processes as well as the shaping of the materials in order to get extrudates, pellets, balls, … which could be used in real conditions (first in pilot equipment).
• the scaling up of the reactions: preparation of polyglycerol or of polyglycerol.