Usos de la GLicerina del Biodiesel
Glycerin Recovery System: This method is to use an Artisan
Rototherm® mechanically-agitated thin film processor to
continuously evaporate and distill glycerin and other heat
sensitive solids-containing products, without color formation,
while achieving greater than 96% yield. Owing to its
extremely short residence time, narrow residence time
distribution, rapid surface renewal, and high heat transfer
rates, product degradation is minimized, while purity and
yield are maximized. Vegetable oil containing 20% glycerin
and 2% sodium salts, through continuous vacuum
evaporation/distillation, highly purified glycerin is recovered
overhead while a concentrated oil/salt residue is discharged
A variety of economic, environmental and technical factors have encouraged industry attention on producing industrial chemicals from bio-feedstocks, rather than from crude oil derivatives. One such example is producing propylene glycol (PG) from glycerine (GLY), rather than the conventional routes starting with propylene monomer.
Propylene glycol has historically been produced in commercial quantities either via the chlorohydrin process or by peroxidation, both using propylene monomer as the starting material. Both routes produce propylene oxide (PO) as an intermediate chemical, which is then hydrated to propylene glycol. The peroxidation routes have evolved from those processes (Arco Chem/Lyondell, Repsol, Shell, BASF) producing a significant amount of by-product (PO/styrene monomer, PO/tertiary butyl alcohol, PO/ methyl tertiary butyl ether), to more recent processes developed by Solvay, Dow and BASF that eliminate the by-product by using hydrogen peroxide as the oxidizing agent.
There is clearly an attraction to de-coupling propylene glycol from petroleum and exploiting the predicted surplus of glycerine is one way of achieving this.
In the new Davy process, glycerine is reacted over a heterogeneous catalyst with hydrogen at moderate conditions. Fresh glycerine together with a recycle stream is vaporised in a recirculating stream of hydrogen, with a suitable quantity of make-up hydrogen, typically from a pressure swing adsorption unit. Per-pass glycerine conversion is around 99% and byproducts are removed by distillation. The advantage of the Davy scheme is high selectivity to the desired product. The refining scheme recovers high purity propylene glycol, whilst water produced in the reaction is of suitable quality to be passed to a biological treatment plant. Propylene glycol product specification meets the requirements of the target markets, namely unsaturated polyester resins and functional fluids, although pharmaceutical grade material can be produced if required. The relatively small by-product streams are of high quality and can be used as solvents or (in the case of the mixed glycols) functional fluids.
In the new process, glycerine is reacted over a heterogeneous catalyst with hydrogen at moderate conditions. Fresh glycerine together with a recycle stream is vaporised in a recirculating stream of hydrogen, with a suitable quantity of make-up hydrogen, typically from a pressure swing adsorption unit. Per-pass glycerine conversion is around 99% and byproducts are removed by distillation. The advantage of the Davy scheme is high selectivity to the desired product. The refining scheme recovers high purity propylene glycol, whilst water produced in the reaction is of suitable quality to be passed to a biological treatment plant. Propylene glycol product specification meets the requirements of the target markets, namely unsaturated polyester resins and functional fluids, although pharmaceutical grade material can be produced if required. The relatively small by-product streams are of high quality and can be used as solvents or (in the case of the mixed glycols) functional fluids.
El glicol de propileno es una sustancia líquida sintética que absorbe agua. El glicol de propileno se usa para fabricar compuestos de poliéster y como componente principal en soluciones para deshelar. El glicol de propileno es usado como anticongelante en industrias químicas, de alimentos y farmacéuticas cuando un escape de agente anticongelante podría hacer contacto con los alimentos. La Administración de Drogas y Alimentos (FDA) ha clasificado al glicol de propileno como un aditivo «que generalmente se estima que es seguro» para uso en alimentos. El glicol de propileno se usa para absorber el exceso de agua y para mantener la humedad en ciertos medicamentos, cosméticos o alimentos. El glicol de propileno también se usa para producir humo artificial en el adiestramiento de bomberos y en obras de teatro. Otros nombres del glicol de propileno son: 1,2-dihidroxipropano, 1,2-propanediol, glicol de metilo y glicol trimetílico.
El glicol de propileno es un líquido incoloro levemente espeso a temperatura ambiente. Puede existir en el aire en forma de vapor, aunque debe ser calentado o agitado enérgicamente para que se transforme en vapor. El glicol de propileno prácticamente no tiene olor ni sabor.
Propylene glycol is used:
- As a solvent in many pharmaceuticals, including oral, injectable and topical formulations. Notably, diazepam, which is insoluble in water, uses propylene glycol as its solvent in its clinical, injectable form.
- As a humectant food additive, labeled as E number E1520
- As an emulsification agent in Angostura and orange bitters
- As a moisturizer in medicines, cosmetics, food, toothpaste, mouth wash, and tobacco products
- As a carrier in fragrance oils
- As an ingredient in massage oils
- In hand sanitizers, antibacterial lotions, and saline solutions
- In smoke machines to make artificial smoke for use in firefighters‘ training and theatrical productions
- In electronic cigarettes, it is used to deliver vaporized nicotine
- As a solvent for food colors and flavorings
- As an ingredient, along with wax and gelatin, in the production of paintballs
- As a moisture stabilizer (humectant) for snus (Swedish style snuff).
- As a cooling agent for beer and wine glycol jacketed fermentation tanks
- As a less-toxic antifreeze in solar water heating systems
- As a solvent used in mixing photographic chemicals, such as film developers
- In cryonics
- As a working fluid in hydraulic presses
- As a coolant in liquid cooling systems
- To regulate humidity in a cigar humidor
- As the killing and preserving agent in pitfall traps, usually used to capture ground beetles
- As an additive to pipe tobacco to prevent dehydration.
- To treat livestock ketosis
- As the main ingredient in deodorant sticks.
- To de-ice aircraft.
- As an ingredient in UV or blacklight tattoo ink
Propylene glycol has properties similar to those of ethylene glycol (monoethylene glycol, or MEG). (Note: Infrequently propylene glycol may also use the acronym MEG, but as an abbreviation of methyl ethyl glycol- the industry standard acronym for propylene glycol is PG or MPG (monopropylene glycol). The industrial norm is to replace ethylene glycol with propylene glycol when safer properties are desired.
Biodiesel Magazine catches up with a few of the researchers investigating innovative chemical and biological processes for the conversion of glycerin into value-added products including antifreeze agents, hydrogen, fortified milk and ethanol.
Much research by several companies and academic groups centers on breaking into the propylene glycol (PG) market with a biobased form of the compound produced from glycerin. At this time, PG is almost exclusively made from propylene oxide, a derivative of propylene, which is a petrochemical feedstock. The yearly demand for PG exceeds 2 billion pounds and growing. The compound is used in everything from pet food and paints to polyester resins, lubricants, antifreeze and cosmetics.
In early May, Cargill Inc. and Ashland Inc. announced a joint venture to develop and produce a range of biobased chemicals. The first product to be marketed will be renewable PG, which the two companies expect to commercialize by mid-2008 and produce at a 65,000-metric-ton-per-year plant to be built in Europe, although the exact plant location has yet to be determined.
“Cargill, and some of our competitors [including Dow Chemical Co., Archer Daniels Midland Co. and Huntsman Corp.], have been exploring options to convert glycerin into a range of industrial bioproducts—the most promising of which is propylene glycol,” says Jim Millis, technical director of industrial bioproducts for Cargill. “We’ve explored a number of technologies and approaches to converting glycerin to PG. We’ve settled on an approach that uses a combination of proprietary and licensed technology that we believe has significant advantages.”
In addition to these two processes this report also provides a detailed design of the glycerin purification section that is needed to allow these processes to take advantage of lower cost crude glycerin which is readily available form may bio-diesel production facilities.
Cost-Competitive Biorefinery Solution: Feedstocks and end products can be optimized based on local market conditions. This fast and continuous (versus batch) process lowers capital expenditures, while low energy requirements reduce operating costs. Together, these attributes provide a biorefinery solution with a broad mix of high value products and attractive market returns
In their hunt for new uses for glycerin, Shulin Chen’s team of biological systems engineers at Washington State University in Pullman work with a strain of algae that can turn pretty much any organic-carbon source into high concentrations of omega-3 fatty acids. These nutritional elements have garnered great interest as health promoters since the early 1980s when researchers recognized that despite their high-fat diets rich in fish, Inuit people show surprisingly low rates of heart disease. It turns out that fatty fish are full of omega-3 fatty acids and subsequent studies have suggested that these molecules, which the human body doesn’t produce naturally and therefore must obtain from the diet, may also play a role in brain function and normal growth and development.
Chen chose glycerin for his carbon source, which he mixes with algae in a fermentor. He then lets the algae feed on the glycerin for a couple of days allowing time for the algae to convert this byproduct of biodiesel production into omega-3 fatty acids—in fairly high concentrations, Chen says. “We’ve found that from 17 [percent] to over 20 percent of the biomass of the algae is omega-3 fatty acids,” he says. The team recently received a grant from the National Science Foundation, which will fund the scale up of the research to a 30-liter fermentor and then to a 100-liter fermentor. From there it will go to the pilot-plant stage, Chen explains.
The question then becomes, what does he do with the omega-3 fatty acid-rich algae? He turns that biomass into milk of course. “Once you have the algae you can do one of two things. You can either extract the fatty acids from the algae or you can feed the algae to animals and use the animals as extractors,” Chen explains. Chen’s team will be studying the latter of those processes within the next year. They will feed the algae to dairy cows and then determine how much of the omega-3 fatty acids ends up in the milk. “This puts the omega-3s into a product that people use on a daily basis,” he says. “Rather than treat the waste as waste we turn it into an actual product.”