———The development of biodiesel industry caused excessive glycerol
The rapid increase in investment in biodiesel has caused an excess of glycerol, a by-product of the production process. Since about 1 kg of glycerol is produced per kg of biodiesel produced, the search for new ways to use these glycerines has attracted worldwide attention. New technologies developed by chemical companies have also come out one after another.
Dow Chemical announced at the end of March this year that it will use new renewable resource technologies to build 150,000 tons/year of epichlorohydrin units and 100,000 tons/year of epoxy units in Shanghai. The world-scale device will be the first application of Dow Chemical's new technology for glycerol, which will use glycerol, a by-product of biodiesel, as a raw material.
Solvay has also developed a new process for the production of epichlorohydrin by reacting glycerol with hydrogen chloride. The process uses proprietary catalysts to produce the intermediate dichloropropanol in one step without the use of chlorine. Solvay has built a new epichlorohydrin plant at its production site in France. It will use glycerol as a by-product from the production of biodiesel from rapeseed oil. The initial production capacity of the unit is 10,000 tons/year, which can be expanded according to market demand. Solvay has signed a long-term glycerin supply contract with a French biodiesel company.
At the same time, Davy Process Technology adopted a new catalyst system and successfully developed a process for producing ethylene glycol using glycerol, a by-product of biodiesel, as a raw material. The catalyst is a homogeneous hydrogenolysis catalyst based on noble metal salts and organophosphine ligands. The reaction proceeds in a homogeneous liquid phase with a conversion of up to 90%.
Professor of Chemical Engineering at the University of Missouri and scientists from the Renewable Alternative Resources Office collaborated to develop a process for the production of propylene glycol from the biodiesel by-product glycerol. According to reports, the propylene glycol yield of this process can be higher than 73%.
In addition, ADM, Cargill and several other companies have also developed a new process for the production of propylene glycol from biobased glycerol. At present, global propylene glycol supply is still relatively scarce, and emerging technologies provide opportunities for propylene glycol producers.
Brazilian researchers also developed new uses for glycerol. They use platinum catalysts to decompose glycerol into hydrogen and CO under relatively mild conditions.
China is currently the world's largest epoxy resin production base, and the demand for epichlorohydrin products is very large. In the face of this market opportunity, Jiangsu Polytechnic University has also successfully developed a technology for the direct production of epichlorohydrin by glycerol. The glycerol process developed by them has obvious advantages over propylene high-temperature chlorination and acryloyl acetate: loose resource conditions and no consumption of propylene; safe and reliable, without the use of chlorine and hypochlorous acid; low investment, only propylene method One-quarter; low cost, 3,000 yuan less per ton than the propylene process; moderate operating conditions, greatly reduced pollution, wastewater is one-tenth of the propylene process; does not require expensive catalysts.
From the perspective of renewable glycerol, the use of bioconversion technology to produce bulk pharmaceutical chemicals dihydroxyacetone has also become possible in China. The microbiological dihydroxyacetone production process developed by the Institute of Bioengineering, Zhejiang University of Technology, has completed 50- to 100-liter batch bioreactor experiments, and is currently conducting pre-industrial trials of 20-60 tons of fermentation tanks.
The mechanism of biological production of DHA is the use of glycerol dehydrogenase produced by microorganisms to dehydrogenate the hydroxyl groups of glycerol to produce 1,3 dihydroxyacetone. Throughout the entire process, the selection of microbial strains and crystallization processes for highly active glycerol dehydrogenase is the key to this project.
In the study of biological DHA, Zhejiang University of Technology has screened microorganism strains capable of producing glycerol deaminase and applied for national invention patents. According to reports, DHA is an important chemical raw material, pharmaceutical intermediates and food additives for a wide range of uses. It can be used for aldol condensation to produce a variety of chiral compounds, can also produce some cyclic compounds, but also can be used as a cosmetic colorant.