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Biochemistry

Green petrochemicals

Left over glycerin from biodiesel production will be used polypropylene production

Miguel Boyayan Blond glycerin: if unused, it may be disposed of poorlyMiguel Boyayan

The quest for raw materials as an alternative to oil derivatives is currently on the agenda for the production of plastic. The high price of raw oil in the world market and the need for environmentally friendly products, whether degradable or produced from renewable resources, have helped to open new technological paths for this type of industry. In Brazil, the most recent novelty is using glycerin, left over from the manufacturing of biodiesel, to produce propylene, a resin that up to now was obtained from oil products and used to make polypropylene (PP). This is a plastic widely employed in automobiles, domestic appliances, disposable syringes, nappies, food packaging and cleaning products.

The development of the production alternative comes from the firm Nova Petroquímica, the former Suzano, which, since June of this year, has become part of the Quattor conglomerate, comprised of Petrobras and the Unipar group. Production is due to start in 2009, in the form of a pilot plant in a location yet to be defined. After this, it will be the turn of a permanent plant, to be set up by 2014. These industrial investments should reach US$50 million in total. The company’s production route is similar to that of other major manufacturers of raw materials for plastic, such as Braskem, Dow Química and Oxiteno (read about this in Pesquisa FAPESP issue no.142), all of which have projects for producing polymers of vegetable origin primarily from sugarcane. Along with the biodiesel glycerin, they are forming a green or renewable petrochemical chain.

The production of PP from glycerin is important because it involves large figures as in the production of both biodiesel and the resin itself, for which Quattor has a 45% market share (equal to 875 thousand tonnes a year of polypropylene) and exports to 40 countries. According to a survey carried out by the company, the glycerin volume available in 2008 should reach some 105 thousand tonnes if production reaches 1 billion liters of biodiesel, to make up the compulsory quota of 2% added to diesel, this being the main fuel for trucks and buses in Brazil. In 2013, when this percentage rises to 5% of biodiesel, surplus glycerin should reach 250 thousand tonnes.

The problem is that the Brazilian market consumes only 40 thousand tonnes of glycerin a year. Glycerin is the commercial name of glycerol, which can be made from vegetable oils or oil products, such as propylene itself. Making plastic out of it is yet another of its many industrial uses. It is used in cosmetics; it is found in the pharmaceutical industry, in the composition of capsules, syrups and ointments; in the chemical industry, it goes into paints, varnishes and detergents; in the food products industry, it is used to conserve beverages and foods, such as soft drinks, candies, cakes, meats and rations; and it is also used in packaging. In the tobacco industry, glycerin makes the tobacco fibers more resistant and keeps leaves from drying out; likewise, it is used to soften and increase the flexibility of textile fibers. Out of every thousand liters of biodiesel made by the transesterification process, which adds vegetable oil or animal fat from several sources and one type of alcohol (methanol, more commonly used, or ethanol), there are about 100 liters left over at the end. The price has also plummeted in the recent past. A kilogram of the product used to be worth US$1.55 in 1995; it has since dropped to US$0.50 in 2007.

“We found that the current glycerin consumers would never be able to use the entire production”, says Pedro Geraldo Boscolo, a Quattor manager. It was after this increased supply of glycerin came into being that the firm sought out professor Claudio Mota, from the Chemistry Institute of the Federal University of Rio de Janeiro (URFJ) in 2006. “The motivation came from them and at first I thought it would be difficult to remove the oxygen atoms from glycerin (C3H8O3) to turn it into propylene (C3H6)”, recalls Mota. “Although there were no references to this in the scientific literature, we managed to come up with a good system, extracting oxygen as water”. The chemical reaction yields water, which is a benefit, because this too can be sold or used by the industry itself. A patent was deposited, with profits to be split fifty-fifty between UFRJ and the project researchers, on one hand, and the corporation, on the other. R$2 million were invested in the project, of which R$600 thousand came from Finep (the Studies and Projects Finance Agency) and the rest from Quattor.

Other uses
When he received the firm’s invitation, Mota was already working on obtaining glycerin compounds to use as gasoline or diesel additives. “We’re developing glycerin products that can be mixed in with these fuels to lubricate the engine better, besides reducing the sulfur and particle compounds content in the case of diesel. Regarding gasoline, they can reduce the production of carbon monoxide (CO) and  other pollutants and improve engine performance”, explains Mota. He  is also studying the production of acrylic plastics with glycerin. “Everything is in line with the expected biodiesel production increase”.

The green polypropylene production system developed by the company and UFRJ jointly begins with planting soy, currently the main oleaginous plant used to produce biodiesel. According to Quattor data, out of every 3 thousand kg of grain harvested in 1 hectare, 540 kg of oil are left over, to which 54 kg of methanol are added. The result is 540 kg of biodiesel and 54 kg of glycerol. This glycerin will yield 27 kg of propylene and the same amount of polypropylene. Although glycerin is marketed and measured for use in kilograms, it is actually a liquid. “This product is being carried from the biodiesel producers to our plant by truck”, explains Boscolo.

Using glycerin from biodiesel involves another aspect which supports these studies and the need to increase its industrial use: the possibility of it being discarded as effluent or waste should there be no use for it. “This glycerin is slightly different from the one in oil products. Instead of being transparent, it is yellowish and contains 9% of residues. Because of its color, it’s called blond glycerin and lacks a clearly defined market, which is why it can end up being disposed of inappropriately”, says professor Derval dos Santos Rosa, academic dean at the Campinas campus of São Francisco University, which is headquartered in Bragança Paulista, in inner-state São Paulo. Studying the use of glycerin and  the commercial type as a plasticizer, the additive that provides the greatest resistance and elasticity for plastics, he and students Marcelo Bardi and Luciano Rigolo, from the Itatiba School of Engineering of the same university, showed that it would be useful in plasticizing polymers produced from starch, a substance called polysaccharide, found in many vegetables.

Environmental danger
“Blond glycerin resulted in better mechanical properties, such as resistance to traction and stretching, than the commercial kind offers”, says Rosa. They presented their study at the PlastShow Congress in 2008, held in May, in São Paulo. In this work, they mention, for instance, that surplus glycerol is being disposed of in the river Poti, which damages the environment, in the town of Crateús, in the state of Ceará, a biodiesel producing region. “Once we called a biodiesel producer to ask for some samples for research and they asked us how many tonnes we wanted”, recalls Rosa, who was astonished at the time because all he needed was a few kilograms. “Plasticizing starch is one alternative for producing more environmentally friendly biodegradable plastics, using glycerin from biodiesel”. Other alternatives for glycerin, other than plastic, are burning it to produce electric energy in the manufacturing of biodiesel itself, or using it as a less toxic alternative to ethylene glycol in anti-freeze products and as an ingredient in sweeteners and a moisturizing agent in food.

Sônia Faria Zawadzki/UFPR PVC with vegetable resin, on the left, and non-plasticizedSônia Faria Zawadzki/UFPR

Renewable plasticizer

The vegetable route is also at the heart of a new product that may replace an additive used by the plastics industry to lend added softness and flexibility to PVC objects. PVC is the second most used plastic in the world, “We got a renewable plasticizer made from vegetable oil to replace phthalates (produced from fossil oil products)”, stated professor Sônia Faria Zawadzki, from the Chemistry Department of the Federal University of Paraná (UFPR). Phthalates are a set of chemicals found – especially in association with PVC – in the formulation of plastic bags or food-wrapping film; they are also found in toys, bathroom curtains, cosmetics packaging, catheters, and blood and serum bags. They are suspected of being harmful to human health.

Studies show that phthalates, even in small doses, can contaminate foods and beverages; they are then ingested by adults and children. They are linked to cancer, body malformations, and endocrinal and hormonal problems, especially damage to the male reproductive system. The chief suspect is a type of plasticizer called DEHP (bis(2-ethylhexyl)phthalate), often used in plastic films. “It has been proven that in mice they cause pancreatic, kidney and liver cancer, but it is still controversial when it comes to humans”, says professor Sonia. Anvisa, (Brazil’s National Sanitation Surveillance Agency) requires that products sold in Brazil have no more than 3% of phthalates. “But data in the domestic and the international literature show figures higher than this, especially in plastic films and bags, products made really soft thanks to plasticizers”.

The product developed at UFPR to replace phthalates and to plasticize PVC started being worked on in 2003. The research, coordinated by professor Sonia along with professor Luiz Pereira Ramos, reached the pre-industrial stage thanks to a partnership agreement with the local branch of an American corporation, Corn, which processes raw vegetable material for the food, chemical and pharmaceutical industries. Corn began investing in this research after professor Sonia developed the formulation and showed it to the company. The company is now assessing the industrial implementation of the product, some details of which cannot be revealed yet, such as the vegetable oil from which it is made, although a patent for it has been deposited. The new plasticizer will cost about 10% less that conventional phthalates.

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