Renewable Raw Materials

May 29, 2006

Petroleum and natural gas reserves are getting smaller and smaller. It is thus a real waste to burn up these valuable resources for heat or transportation especially as "black gold" is also the most important starting material for the chemical industry.

It is used in the production of most organic compounds, be they plastics, medicines, or solvents. We clearly need alternatives and are scouring nature in the hope that renewable plant resources will eventually provide some real competition for fossil resources.

For example, the enzymatic extraction of cellulose from wood by-products produces the sugar glucose, which is then fermented to form ethanol. This ethanol can then be used as a “biological” fuel for vehicles. Under different reaction conditions, the fermentation of glucose produces glycerol. Glycerol is also a highly promising starting material for the synthesis of fuels and other organic compounds, as a team of scientists from the USA and Brazil have discovered.

J. A. Dumesic and co-workers have developed a process in which platinum-based catalysts are used to break down glycerol to hydrogen and carbon monoxide under relatively mild conditions—temperatures between 225 and 300 °C. This process has several advantages. Among them, glycerol is currently a low-value by-product in the production of biodiesel, and fermentation of glucose produces a 25% solution of glycerol, while the degradation of sugar to ethanol results in a mixture that contains only 5 % of the desired substance. The ethanol must then be separated from this mixture by an energetically demanding distillation, whereas the glycerol-containing solution can be used as is either to produce methanol or to generate longer-chain alkanes in the Fischer–Tropsch process.

In the Fischer–Tropsch synthesis, a 2:1 mixture of hydrogen and carbon monoxide is passed over a cobalt catalyst and heated to 200 °C. Careful selection of the Pt catalyst system allows the ratio of the gases produced in the degradation of glycerol to be adjusted to the value suitable for the Fischer–Tropsch process.

The energy balance for these coupled reactions is also quite favorable: the endothermic degradation of glycerol requires an energy expenditure of 350 kJmol-1. The Fischer–Tropsch synthesis is, in contrast, an exothermic reaction, delivering -412 kJmol-1 of energy. There is thus an overall gain in energy of -62 kJmol-1.

Reference: James A. Dumesic, Glycerol as a Source for Fuels and Chemicals by Low-Temperature Catalytic Processing, Angewandte Chemie International Edition 2006, 45, No. 24, 3982–3985, doi: 10.1002/anie.200600212

Source: Angewandte Chemie

Explore further: Scientists develop a water splitter that runs on an ordinary AAA battery

add to favorites email to friend print save as pdf

Related Stories

Here's how you find out who shot down MH17

9 minutes ago

More than a month has passed since Malaysia Airlines flight MH17 crashed with the loss of all 298 lives on board. But despite the disturbances at the crash site near the small town of Grabovo, near Donetsk ...

Developers explore game experience for the blind

24 minutes ago

Wait, researchers are talking about a video game for the blind? Come again? Not impossible. Game designers, reports the BBC, have been working on bringing the game experience to the blind and those with vision ...

Apple's freshly sliced shares climb

1 hour ago

Freshly split Apple shares closed at a high on Tuesday, with investors evidently betting the California company will debut popular new gadgets, perhaps a smart watch and an iPhone 6.

France fights back Asian hornet invader

2 hours ago

They slipped into southwest France 10 years ago in a pottery shipment from China and have since invaded more than half the country, which is fighting back with drones, poisoned rods and even chickens.

Recommended for you

Proteins: New class of materials discovered

16 hours ago

Scientists at the Helmholtz Center Berlin along with researchers at China's Fudan University have characterized a new class of materials called protein crystalline frameworks.

The fluorescent fingerprint of plastics

Aug 21, 2014

LMU researchers have developed a new process which will greatly simplify the process of sorting plastics in recycling plants. The method enables automated identification of polymers, facilitating rapid separation ...

User comments : 0