New reaction offers sustainable route to biodiesel

A new chemical reaction that converts waste glycerol from biodiesel production into methanol – a necessary reagent in biodiesel production – has been discovered unexpectedly by UK researchers. The work, which is still at a preliminary stage, could theoretically allow biodiesel to be produced entirely from renewable resources, cutting the need for fossil fuel based methanol.

In the transesterification process of biodiesel production, the carbon chain of a molecule of vegetable oil is broken into three. At each break, a hydrogen atom from methanol is substituted for the link to the adjacent carbon atom. The production of biodiesel, however, leads to the formation of large quantities of crude glycerol – around 10% of the mass of biodiesel created – but is generally uneconomical to refine. Researchers are seeking ways to convert this waste product into something useful, and some efforts have focused on the dehydration reaction to acrolein – used as a herbicide and polymer precursor. This reaction is usually acid-catalyzed, but researchers at Cardiff University considered that it could also be base-catalyzed and investigated this using magnesium oxide. Much to their surprise, they found that the main product was not acrolein but methanol.

                        The proposed mechanism for methanol formation from glycerol

As a result of these experiments, which included isotopic labelling of reactants, the researchers determined that the glycerol was being reduced back to methanol by carbon–carbon bond scission and reduction using water as a hydrogen source. They hypothesize that the reaction can take place by either of two mechanisms: the first begins with double dehydration to acrolein and the second proceeds via the ethylene glycol radical and hydroxyethanal. Further investigations showed that cerium dioxide was a more effective catalyst than magnesium oxide, achieving complete conversion with methanol selectivity of 60%. The work is still at an early stage but the researchers have closed the sustainability loop for the transesterification process of biodiesel.

The use of fuel additives to improve biodiesel quality characteristics

Modern fuel additives are very important both for improving fuel properties, as well as to increase engine longevity and improve technical characteristics. Effective characteristics of the engine also depend on the engine design, the materials and production technology of its components.

On the other hand, even the engines are being constantly improved during operation of a great number of extraneous factors such fuel, oil, coolant; various sealing elements reduce their economy. Engine parts and elements wear and rub themselves during chemical and thermal processes. Although the intervals between the vehicle services are becoming longer because of improved technologies, the engine still remains one of the key elements for service. So the lengthening of the engine durability is the main object of interest for users as well as for manufacturing or service organizations. For this reason the view that the application of additives in improving fuel properties is a way to solve a number of issues related to the motor operating characteristics improvement is becoming stronger.

In the recent year’s multifunctional additives which act systemically improving lubrication, cleaning, burning, corrosion and other properties are becoming more popular. These accessories appeal to consumers as they improve some fuel properties and have multiple effects. They accelerate the combustion in the cylinder of the engine as make fuel burn more smoothly.

Τhe biodiesel physical properties can be uplifted by using different additives including metal based additives, antioxidants and oxygenated additives, cold flow improver etc. into biodiesel to solve the problem of cold flow properties for their large number of usage in diesel engines. Some additives were used to improve the performance and reduce exhaust emissions from diesel engines.

The range of benefits accruing from fuel additives is very significant and includes:

- Protection of fuel tanks, pipe lines and other from massively expensive corrosion.

- Protection of fuel system equipment in the diesel engine from catastrophic premature wear.

- Reduced pumping costs and energy use in long-distance fuel pipelines.

- Reduced refinery processing needed to meet fuel cetane and specifications.

- Cold flow improvement in middle distillates, maximizing use of bio fuel.

- Stability improvement to prolong storage life of fuels throughout the operating theatre.

- Fuel saving from optimized vehicle performance and economy.

- Emission reduction from fuel system cleanliness and combustion optimization.

Biodiesel is non-explosive, nontoxic, non-flammable and biodegradable fuel which provides reduction of many detrimental exhaust emissions. It has no SO_X emission, particulate and soot and it can be reduced polycyclic aromatic hydrocarbons emissions.

However there are some disadvantages associated with the use of biodiesel fuels.

Some biodiesel fuel increases NO_X emission, which have rigorous environmental regulations and relatively poor low temperature flow properties compared to conventional diesel. Another demerit is the oxidation stability of biodiesel because of containing the double bond molecules in the free fatty acid. Fuels containing bio-components present special challenge in use, for which a range of additives provide valuable benefits. Aspect includes:

- Reduce oxidation stability.

- Potential for increased injector deposit formation.

- Corrosion in long term storage.

- Adverse effect on cold flow characteristics.

- Increased microbial contamination.

It is considered that fuel physical properties (density, viscosity and cooking area) do not change. However, their influence on engine performance and durability requires further studies.

The quality of biodiesel can be bettered by improving the technological processes, production, careful selection and processing of raw materials. However, their properties can also be improved by use of special additives which affect each characteristic or the entire set of them. Consequently, the composition of biodiesel and the use of additives directly affect such properties as viscosity, density, behavior at low temperatures, Volatility, and the cetane number. Popularity of complex (multifunctional) additives which act systemically improving lubrication, cleaning, burning, corrosion and other properties have been growing recently. Their influence on the properties of biodiesel and engine efficiency and durability requires further studies.

The advantage of biodiesel manufacturing by heterogeneous base catalyst

The manufacturing of biodiesel by heterogeneous catalysis has major economic benefits compared to the traditional homogeneous catalysis.

The main reason is the suppression of operations generating large amounts of waste water (except during feedstock pretreatment), namely the catalyst removal by acid/base neutralisations, washing of FAME and glycerol, as well as at methanol recovery by distillation of aqueous solutions.

There is no salt waste, and catalyst consumption drops dramatically.

In the homogeneous process the glycerol has maximum 85% purity after expensive separations, while the heterogeneous process delivers glycerol that is >98% pure, a valuable product.

In addition, the continuous operation is intrinsically more efficient than batchwise. Heterogeneous catalysis may be applied both to low and to high FFA oils. In the last case a preliminary esterification with methanol is necessary, which can be performed by employing solid acid catalyst, as e ion-exchange resins.

The small amounts of water  formed can be removed simply by adsorption. Higher FFA lipids, as animal fat and industrial greases, can be treated in a reactive distillation device.

EU biofuels blending economics turn towards ethanol from biodiesel

Increasing outright FAME 0 prices over the course of April and ethanol prices holding below Eur500/cu m have resulted in European blending interest turning from biodiesel to ethanol.

At the beginning of the year, biodiesel was highly favored over ethanol. Over the first quarter, the price of T2 ethanol averaged $288.24/cu m over Eurobob gasoline. By Thursday 28^th April evening, though, this premium had fallen to $172.98/cu m as Eurobob gasoline (The Argus Eurobob oxy assessment is used as a benchmark price in gasoline transactions throughout northwest Europe. Eurobob is an unfinished gasoline and the European swaps market shifted to price against this ethanol-ready blendstock in January 2010) increased substantially more than ethanol day-on-day.

In January and February, blenders were reducing their incorporation rates of ethanol as much as possible, in an attempt to wait out the higher premiums in the hope that ethanol prices would fall and gasoline would increase.

RED FAME 0 outright prices had been generally on a firming trajectory for the most of April, on the back bullishness in vegoils complex, which kept feedstock prices at strong levels.

Outright prices on RED FAME 0 averaged at around $766/mt during Q1 and $857/mt for April, whereas the comparable T2 ethanol prices were at $718/mt and $668/mt respectively. RED FAME 0 was last assessed at $863/mt Thursday, whilst T2 ethanol stood at around $688/mt.

Eurobob gasoline barges were assessed at $489.75/mt on Thursday at a discount of $10/mt to the front-month swap, up from $479.75/mt Wednesday, when the discount to the front-month swap was $5.75/mt.

Although the energy content of biodiesel is relatively higher than that of ethanol, the divergent price movements between the two biofuels has shifted blending economics in favor of ethanol.

"The logic is that people start using more cars as of now, and blenders should blend more ethanol given better blending economics," one source said, adding that the sustained premium of ethanol over Eurobob was "not good, but better. It would make sense to blend more now."

European gasoline demand is expected to strengthen on the back of the US summer driving season, which typically represents a seasonal peak of demand for the road fuel, and absorbs European arbitrage barrels.

The May USAC-UKC arbitrage swap -- which tracks the differential between US RBOB and Northwest European Eurobob forward values -- widened on Thursday leading to more support for the arbitrage from the Northwest Europe to the US Atlantic Coast. The swap rallied to break the 16 cents/gal mark, as a function of the more rapid fall in European cracks at a time of global oversupply, and an overall rebalancing of European values to open arbitrage outlets.

"It is getting heated as arb goes wider," said a trading source.

Improved price differentials between the two regions may be a catalyst for the opening of the spot market arbitrage.