The bioeconomy at work: Dow develops propylene glycol from biodiesel residue

The Dow Chemical Company announced a significant milestone in its pursuit of plant-based chemistries, with the introduction of monopropylene glycol derived from renewable, biological resources. Its 'Propylene Glycol Renewable' (PGR) is made from glycerin (glycerol) generated during the manufacture of biodiesel, produced from vegetable oils.

The use of biofuel byproducts as a feesdstock for hydrocarbon alternatives is important to increase the value of biofuel production and to make it more competitive with fossil fuels. Propylene glycol is normally made from propylene, a major petrochemical compound synthesised from oil. Now we have a green alternative - another step forward in the emerging 'bioeconomy'.

Glycerin is becoming abundant because of increasing biodiesel production, especially in Europe. Once considered a valuable co-product, crude glycerol is now actually seen as a waste product with an attached disposal cost. Researchers have therefor been looking into utilizing it as a feedstock for new products and markets. Some scientists suggest it makes for an excellent poultry feed additive, others see it as a suitable biogas feedstock (earlier post), whereas still others are trying to make liquid fuel out of it (previous post).

Dow joins the group and has found its own high-value product for glycerin. The chemical giant is currently conducting PGR trials with customers and anticipates having limited commercial quantities available in mid-2007. PGR will be used in such applications as unsaturated polyester resins (UPR) for boat hulls and bathroom fixtures as well as aircraft deicers, antifreeze for automobiles, recreational vehicles and marine and heavy-duty laundry detergents.

According to Mady Bricco, global product director for the Propylene Oxide/Propylene Glycol division, says that in addition to being manufactured from what is essentially a by-product of the biodiesel process, the production of PGR can be expected to provide additional environmental benefits when compared to propylene-based PG. For example, laboratory tests indicate that manufacturing PGR will consume considerably less fresh water than conventional PG:
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"PGR provides environmental benefits and is cost competitive. It also offers the same outstanding characteristics in terms of quality and performance as our existing PG products," says Bricco. "This breakthrough technology underscores Dow's commitment to deliver products and process technologies that bolster the company's sustainable chemistry aspirations. At the same time, PGR further strengthens our performance business portfolio, delivering an important building block material for a variety of industrial applications."

"We are excited to be at the forefront in developing this innovative, sustainable product. Manufacturers in several downstream industries are demanding the ability to provide more sustainable products to their customers," said Bricco. "Using PGR will enable customers to exercise their commitment to technologies that consume less fossil fuel and other finite resources."

Demand for PG continues to rise, accompanied by a parallel interest in sustainable products, which indicates that the industry is ripe for the introduction of PGR. The PGR product will provide Dow with flexibility in a variety of market conditions as the Company will offer two industrial-grade PG products from two different raw material systems.

"Offering conventional industrial grade PG (PGI) and PGR at the same time will allow Dow to provide customers with greater PG cost stability and predictability," said Bricco. "PGR pricing is independent of the volatility associated with hydrocarbon and energy costs. Meanwhile, we will continue to grow our conventional PGI offering in tandem with the new PGR product, which will liberate Dow from potential, future variability in seed oil and glycerin costs. From an economic standpoint, the dual offering gives Dow and its customers a distinct competitive advantage."

As the world's largest producer and marketer of PG, with more than 60 years of experience in the manufacture of PG, Dow now adds a sustainable product that complements its full PG product offering at economics that make sense in today's marketplace. In addition, customers will experience the same reliable and dependable performance from PGR that they associate with Dow's current industrial grade PG.

Dow has contracted with Dow Haltermann Custom Processing (DHCP), a Dow business unit comprised of operations within The Dow Chemical Company and Johann Haltermann, Ltd. to produce PGR from the crude glycerin generated from the production of biodiesel. DHCP will conduct pilot trials and eventually full-scale production of PGR at its Houston location.

Biodiesel is an alternative diesel fuel made through a chemical process called transesterification where glycerin is separated from vegetable and seed oils such as sunflower, soybean and canola and recycled cooking oil. The process generates methyl esters (biodiesel) and glycerin.

Image: biodiesel production is achieved by transesterifying vegetable oils. Glycerin settling at the bottom of a batch of biodiesel. Biodiesel production results in a fraction of 10% glycerol, making it an important byproduct.