Algae for your fuel tank: New process for producing biodiesel from microalgae oil

Plant oils from sources such as soybean and rapeseed are promising starting materials for the production of biofuels. Microalgae are an interesting alternative to these conventional oil-containing crops. Microalgae are individual cells or short chains of cells from algae freely moving through water. They occur in nearly any pool of water and can readily be cultivated. "They have a number of advantages over oil-containing agricultural products," explains Lercher. "They grow significantly faster than land-based biomass, have a high triglyceride content, and, unlike the terrestrial cultivation of oilseed plants, their use for fuel production does not compete with food production."

Previously known methods for refining oil from microalgae suffer from various disadvantages. The resulting fuel either has too high an oxygen content and poor flow at low temperatures, or a sulfur-containing catalyst may contaminate the product. However, other catalysts are still not efficient enough. The Munich scientists now propose a new process, for which they have developed a novel catalyst: nickel on a porous support made of zeolite HBeta. They have used this to achieve the conversion of raw, untreated algae oil under mild conditions (260 °C, 40 bar hydrogen pressure). Says Lercher: "The products are diesel-range saturated hydrocarbons that are suitable for use as high-grade fuels for vehicles."

The oil produced by the microalgae is mainly composed of neutral lipids, such as mono-, di-, and triglycerides with unsaturated C18 fatty acids as the primary component (88 %). After an eight-hour reaction, the researchers obtain 78 % liquid alkanes with octadecane (C18) as the primary component. The main gas-phase side products are propane and methane.

Analysis of the reaction mechanism shows that this is a cascade reaction. First the double bonds of the unsaturated fatty acid chains of the triglycerides are saturated by hydrogen. Then, the now saturated fatty acids take up hydrogen and are split from their glycerin component, which reacts to form propane. In the final step, the acid groups in the fatty acids are reduced stepwise to the corresponding alkane.

More information: Towards Quantitative Conversion of Microalgae Oil to Diesel-Range Alkanes with Bifunctional Catalysts, B. Peng, Y. Yao, C. Zhao und J.A. Lercher, Angewandte Chemie, 2011. doi:10.1002/ange.201106243

Provided by Technische Universitaet Muenchen

Alligator fat could be used to make biodiesel

 In addition to being a novelty food, alligators could also provide a feedstock for biodiesel. Every year, the alligator meat industry disposes of about 15 million pounds of alligator fat in landfills. Now scientists have found that oil can be extracted from the fat and used to make a high-quality biodiesel.

The researchers, Rakesh Bajpai and coauthors from the University of Louisiana, have published their study on the possibility of using alligator fat as fuel in a recent issue of the American Chemical Society journal Industrial & Engineering Chemistry Research.

In 2008, the US produced about 700 million gallons of biodiesel to help supply some of the 45 billion gallons of diesel consumed that year. Most of the biodiesel came from soybean oil. Due to concerns that using food crops to produce fuels will raise the price of food, scientists have been investigating alternative feedstocks, including sewage sludge, Chinese tallow, and used vegetable oil.

By showing in experiments that oil extracted from alligator fat meets nearly all of the official standards for high-quality biodiesel, the Louisiana researchers have added another feedstock to the list. The scientists explained that alligator fat has a high lipid content, and the lipids could be recovered by microwaving frozen samples and by using a chemical solvent.

Although it would play a small role in biodiesel production if it is ever to be used, alligator fat could have an advantage of lower processing costs compared to some other feedstocks since it is a waste product.

More information: Potential of Alligator Fat as Source of Lipids for Biodiesel Production, Ind. Eng. Chem. Res., Article ASAP, DOI: 10.1021/ie201000s

Abstract
A large amount of alligator fat (AF) is produced by alligator meat processing industry and disposed in landfills or discarded as waste. The AF can be used as a potential feedstock for biodiesel production due to its high lipid content. In this work, recovery of lipids from the AF tissue was studied by solvent extraction as well as by microwave rendering. Microwave rendering resulted in AF oil recovery of 61% by weight of the frozen AF tissue obtained from producers. The fatty acid profile of the lipid showed that palmitic acid (C16:0), palmitoleic acid (C16:1), and oleic acid (C18:1) were the dominant fatty acids accounting for 89–92% of all lipids by mass; 30% of the fatty acids were saturated and 70% were unsaturated. The biodiesel produced from AF oil was found to meet the ASTM specifications of biodiesel concerning kinematic viscosity, sulfur, free and total glycerin, flash point, cloud point, and acid number.

? 2011 PhysOrg.com

A novel enzymatic catalyst for biodiesel production

Continuous production of biodiesel can now be envisaged thanks to a novel catalyst developed by a team at CNRS's Centre de Recherches Paul Pascal (CRPP), in collaboration with researchers from the Institut des Sciences Moléculaires in Bordeaux (CNRS/Université Bordeaux 1/Institut Polytechnique de Bordeaux) and the Laboratoire de Chimie de la Matiere Condensée in Paris (CNRS/UPMC/ENSCP/College de France).

The results, which have been patented, have just been published in the journal Energy & Environmental Science.

Biofuel production provides an alternative to fossil fuels. Biodiesels, for instance, are processed products based on oils from oleaginous plants such as oilseed rape, palm, sunflower and soybeans. They result from a chemical reaction, catalyzed in either an acidic or preferably a basic medium, between a vegetable oil (90%) and an alcohol (10%). This reaction, known as transesterification, converts the mixture into a methyl ester (the main constituent of biodiesel) and glycerol. A saponification side reaction (methyl ester conversion into the corresponding acid salt) reduces methyl ester yield. To increase the yield, it was therefore necessary to develop alternative catalysts (1).

For this type of reaction, certain enzymatic catalysts such as those belonging to the family of lipases (triglyceride hydrolases) are particularly efficient and selective. However, their high cost and low conformational stability restrict their industrial use, unless they can be irreversibly confined in porous matrices, allowing good accessibility and enhanced mass transport. This has now been achieved by the team led by Professor Rénal Backov (Université Bordeaux 1) at CNRS's Centre de Recherches Paul Pascal (CRPP), in collaboration with researchers from teams led by Dr Hervé Deleuze at the Institut des Sciences Moléculaires in Bordeaux (CNRS/Université Bordeaux 1/Institut Polytechnique de Bordeaux) and Professor Clément Sanchez (2) at the Laboratoire de Chimie de la Matiere Condensée in Paris (CNRS/UPMC/ENSCP/College de France).

In an initial study, they had already demonstrated the possibility of efficient catalysis, by developing modified silica-based cellular matrices that make it possible to confine lipases (3) in order to obtain exceptional yields for hydrolysis, esterification and transesterification reactions. Their work had also shown that unpurified enzymes could be used in the matrices. The fact that they were unpurified was a first step to significantly reducing the cost of biocatalysts. However, the methodology did not allow continuous biodiesel production. This obstacle has now been overcome.

Researchers have developed a new method that generates the cellular hybrid biocatalyst in situ inside a chromotography column (4). This novel approach makes it possible to carry out continuous, unidirectional flow synthesis over long periods, since catalytic activity and ethyl ester production are maintained at high, practically steady levels during a two-month period of time. These results are amongst the best ever obtained in this field.

Research is continuing into solvent-free conversion of triesters, aimed at minimizing waste production and curbing the use of solvents and metals in chemical transformation processes. This work, which meets current energy and environmental requirements, shows how much chemists are working in the public interest, and confirms the importance of integrative chemistry.

(1) A catalyst is a chemical substance that increases the rate of a chemical reaction but is not itself used up (it is regenerated).

(2) Professor Clément Sanchez holds the Chair of Chemistry of Hybrid Materials at the College de France.

(3) a/ Enzyme-based hybrid macroporous foams as highly efficient biocatalysts obtained through Integrative Chemistry. N.Brun, A.Babeau-Garcia, H.Deleuze, F.Duran, C.Sanchez, V.Ostreicher and R.Backov. Chem. Mater., 2010, 22, 4555. b/ Catalyseurs supportés enzymatiques hybrides macrocelluaires et applications. N. Brun, A.Babeau-Garcia, C.Sanchez and R.Backov. French patent 2009, file number FR 09-54634

(4) Chromatography is a technique used to separate the constituents of a mixture, with the aim of identifying or measuring certain constituents of the mixture.

How does it work?

These systems are efficient because a certain number of technical obstacles have been overcome:

the confinement of the enzymes in macropores (with diameters of a few micrometers) makes them continuously accessible to reactants in solution. The macroporous medium also means that chemical reactions are not slowed down by Fickian diffusion transport, unlike in matrices with a mesoporous surface (diameters of 2-50 nm), where there is little convection.the enzymes are used in unpurified form, which contributes to their stability and keeps production costs low.hybridization of the surface of the silica support optimizes enzyme/substrate interactions.the natural hydration of the silica cellular support enhances enzymatic activity via a lubricating effect.the mechanical stability of the silica framework makes it possible to maintain a high inlet pressure and pressure drop (difference in pressure between the inlet and outlet of the reactor under continuous flow) without damage, enabling the use of high reactant flow.

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by CNRS (Délégation Paris Michel-Ange).

Journal Reference:

Nicolas Brun, Annick Babeau-Garcia, Marie-France Achard, Clément Sanchez, Fabien Durand, Guillaume Laurent, Marc Birot, Hervé Deleuze, Rénal Backov. Enzyme-based biohybrid foams designed for continuous flow heterogeneous catalysis and biodiesel production. Energy & Environmental Science, 2011; DOI: 10.1039/C1EE01295A

A novel enzymatic catalyst for biodiesel production

 

Continuous production of biodiesel can now be envisaged thanks to a novel catalyst developed by a French team at CNRS's Centre de Recherches Paul Pascal (CRPP). The results, which have been patented, have just been published in the journal Energy & Environmental Science.

Biofuel production provides an alternative to fossil fuels. Biodiesels, for instance, are processed products based on oils from oleaginous plants such as oilseed rape, palm, sunflower and soybeans. They result from a chemical reaction, catalyzed in either an acidic or preferably a basic medium, between a vegetable oil (90%) and an alcohol (10%). This reaction, known as transesterification, converts the mixture into a methyl ester (the main constituent of biodiesel) and glycerol. A saponification side reaction (methyl ester conversion into the corresponding acid salt) reduces methyl ester yield. To increase the yield, it was therefore necessary to develop alternative catalysts.

For this type of reaction, certain enzymatic catalysts such as those belonging to the family of lipases (triglyceride hydrolases) are particularly efficient and selective. However, their high cost and low conformational stability restrict their industrial use, unless they can be irreversibly confined in porous matrices, allowing good accessibility and enhanced mass transport. This has now been achieved by the team led by Professor Renal Backov.

In an initial study, they had already demonstrated the possibility of efficient catalysis, by developing modified silica-based cellular matrices that make it possible to confine lipases in order to obtain exceptional yields for hydrolysis, esterification and transesterification reactions. Their work had also shown that unpurified enzymes could be used in the matrices. The fact that they were unpurified was a first step to significantly reducing the cost of biocatalysts. However, the methodology did not allow continuous biodiesel production. This obstacle has now been overcome.

Researchers have developed a new method that generates the cellular hybrid biocatalyst in situ inside a chromotography column. This novel approach makes it possible to carry out continuous, unidirectional flow synthesis over long periods, since catalytic activity and ethyl ester production are maintained at high, practically steady levels during a two-month period of time. These results are amongst the best ever obtained in this field.

Research is continuing into solvent-free conversion of triesters, aimed at minimizing waste production and curbing the use of solvents and metals in chemical transformation processes. This work, which meets current energy and environmental requirements, shows how much chemists are working in the public interest, and confirms the importance of integrative chemistry.

More information: References:

-- “Enzyme-Based Biohybrid Foams Designed for Continuous Flow Heterogeneous Catalysis and Biodiesel Production”, N.Brun, A.Babeau-Garcia, M.-F.Achard, C.Sanchez, F.Durand, L.Guillaume, M.Birot, H.Deleuze and R.Backov - Energy & Environmental Science, 2011 DOI:10.1039/C1EE01295A

-- Catalyseur enzymatique hétérogene, procédé de préparation et utilisation pour la catalyse enzymatique en flux continu. N.Brun, H.Deleuze, C.Sanchez and R.Backov. French patent 2010. File number FR10-56099.

Provided by CNRS (news : web)

UConn reactor uses more efficient process to make biodiesel fuel

Deep inside the University of Connecticut’s chemical engineering building in Storrs, Professor Richard Parnas and a team of students quietly monitor a murky brown emulsion bubbling inside an enormous 6-inch diameter glass tube like doctors carefully observing a patient undergoing surgery.

Moving among an array of flexible tubing and metal rods surrounding the nearly floor-to-ceiling device, Parnas keeps a watchful eye on a series of multicolored charts blinking on a nearby laptop. The display represents the real-time readings of a high-tech fiber-optic probe monitoring the chemical reactions taking place inside the tube. It helps Parnas, a UConn professor of chemical, materials, and biomolecular engineering, maintain the precise recipe he needs to turn a mixture of methanol, potassium hydroxide, and waste vegetable oil into nearly pure, cheap, environmentally-friendly biodiesel fuel.

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Parnas’ patented biodiesel reactor is unique in both its simplicity and efficiency. In conventional biodiesel production, vegetable oil is converted into biodiesel fuel and glycerol, a byproduct of the conversion process. Then, the glycerol must be mechanically separated from the diesel fuel, as part of a two-step process. Parnas’ reactor is different in that it uses gravity, heat, and natural chemical reactions to make the biodiesel and separate the glycerol in one step.

As the chemical reactions take place inside the giant tube, temperatures reach more than 100 degrees Fahrenheit. The glycerol starts to coagulate in opaque swirls inside the tube. Because the glycerol droplets are heavier than the biodiesel fuel, they gradually sink to the bottom, where they are siphoned off. At the same time, the biodiesel fuel floats to the top of the tube and is pumped into a holding tank, where it undergoes refinement before being mixed with petroleum-based diesel fuel and used in the University’s bus fleet.

“What is unique about our reactor and why we have a patent on it, is that it gives a much better performance for the separation of the glycerol, and we don’t need a special separate step as is used in most other processes,” says Parnas, who also serves as chairman of UConn’s biodiesel consortium research group.

“That motion and those swirls you are seeing when you look at the reactor are the result of both a chemical reaction and phase separation in real time,” Parnas says. “Phase separation is like what happens when you have an oil and vinegar salad dressing … In other biodiesel processes out there, the reactants are very highly mixed and come out of the reactor together.”

The first UConn biodiesel reactor was built by Greg Magoon, a UConn chemical engineering undergraduate student, in 2004. In 2006, a larger continuous flow biodiesel reactor was designed by UConn graduate student Cliff Weed, under Parnas’ tutelage. The reactor in place today was constructed by students Matthew Boucher and Ryan Couture. Undergraduate and graduate students from chemical engineering, chemistry, economics, and natural resources and the environment have been involved with the project over the years. Every chemical engineering student at UConn learns how to make biodiesel as part of the academic program.

Igor Anisimov, a third-semester chemical engineering student, was one of the students helping Parnas with the reactor during a recent production run.

“The biodiesel reactor is exploiting the molecular differences of the elements,” says Anisimov. “By exploiting the natural properties of these chemicals, we can separate the biodiesel from the glycerol. It’s very cool seeing it happening here, compared to seeing it in the classroom on pen and paper.”

The existing facility produces about 2,000 gallons of biodiesel fuel a year. Parnas and colleagues Yi Li of the plant science department, Steven Suib of the chemistry department, Fred Carstensen of the economics department, and Harrison Yang of the Department of Natural Resources and the Environment are preparing to build a larger pilot biodiesel production facility using part of a two-year, $1.8 million grant from the Department of Energy. The reactor will be capable of producing up to 200,000 gallons of biodiesel a year. Parnas says the pilot plant’s production can easily be magnified for larger-scale commercial production.

In an era of rising gasoline prices and increasing worry about global warming and the emission of greenhouse gases, biodiesel is proving to be a valuable and important substitute for traditional petroleum-based fuels.

Biodiesel releases more energy than is consumed during its production, making it four times more efficient than traditional diesel fuels. It is a renewable fuel source that can be produced locally, cutting down on transportation costs, greenhouse gas emissions, and the nation’s reliance on foreign oil reserves. And, since it is made from plant materials, biodiesel is 100 percent biodegradable.

Provided by University of Connecticut (news : web)