Dow studies bio-based propylene routes

28 February 2011 00:00  [Source: ICB]

Dow Chemical explores methods for producing its key feedstocks from renewable resources

Dow Chemical is studying the optimum routes for producing its main feedstocks, ethylene and propylene, from renewable resources. The US-headquartered company is already pursuing a project to produce ethylene and polyethylene (PE) from sugarcane ethanol in Brazil, and is evaluating different methods for producing bio-based propylene.

 
Rex Features
As well as developing the necessary process technologies, the company is examining which bio-based products it would be able to sell at a premium. "Each of the regions is looking from a markets point of view," said Theresa Kotanchek, Dow vice president for sustainable technologies and innovation sourcing. "We're examining an array of raw materials."

Dow sees opportunities in sectors including personal care, cleaning products and the replacement of phthalates as plasticizers, Kotanchek said. "The opportunities cut across multiple end-use markets," she added.

It is early days. Dow's research and development (R&D) teams are investigating which bio-derived products the company should be focusing on. The research is still exploratory, explained John Biggs, R&D development director for Dow's hydrocarbon and energy group in Latin America.

BRAZILIAN ADVANTAGE
Producing PE from ethanol made from Brazilian sugarcane is Dow's first commercial priority.

 "Each region is looking from a markets point of view"
Theresa Kotanchek, Dow vice president for sustainable technologies and innovation sourcing
Dow's plans to build an integrated complex for the production of PE based on sugarcane ethanol in Brazil were delayed after the original joint venture partnership with Brazilian ethanol producer Crystalsev was dissolved. However, Dow intends to resurrect the project with a new joint venture partner.

"We're in the position where we are trying to find another partner," said Kotanchek. Deciding the business partnership structure will be the critical milestone, she added.

In the meantime, Dow is progressing the 350,000 tonne/year PE project alone.

"We feel confident about the project, which is important for the supply of PE in Latin America," she remarked.

Backward integration into sugarcane will be key to the project, she said. Integration will enable the project to be competitive compared with PE manufactured from hydrocarbon-based feedstocks, she explained. While the project is not predicated on a price premium for the bio-based PE, "it is likely we will be able to position it as a premium product," she said.

 "The market for [bio-based PE] is already there. The product could be sold a number of times over right now"
John Biggs, R&D development director, hydrocarbons and energy - Latin America, Dow Chemical
"The market for the product is already there," enthused Biggs. "The product could be sold a number of times over right now."

Ultimately, the market will dictate the prices and hence the margins for bio-based products. Some 30% of consumers are willing to pay a 10% premium for bio-based products, according to Jorge Fergie, a partner at US-based consultancy McKinsey & Co. He predicts bio-based products could account for some 8% of chemical sales by 2012, with sales increasing as crude oil prices continue to rise.

Government policies to increase self-sufficiency in energy are also expected to boost demand for bio-based products, Fergie said.

PRICE PREMIUM
Braskem has demonstrated there are certain market segments in which the value of bio-based PE is high, the Dow officials noted. The Brazilian producer started up a sugarcane ethanol-based ethylene plant for the production of what it calls green PE at its site in Triunfo, southern Brazil, in September 2010 - and there are plans for a second project.

Braskem has been successful selling its green PE at a premium and has concluded supply agreements with major companies, including consumer goods manufacturer Procter & Gamble, Swedish food packaging company Tetra Pak and Japanese cosmetics company Shiseido.

Braskem's green PE production is not backward integrated. The company, controlled by Brazilian conglomerate Odebrecht, purchases ethanol from Odebrecht subsidiary ETH Bioenergia.

Other chemical producers also plan to build projects in Brazil based on the country's sugarcane. Belgium-based Solvay, for example, intends to build a bio-based polyvinyl chloride (PVC) facility in the country. Solvay's project is expected to have the capacity to produce 60,000 tonnes/year of bioethylene for conversion into PVC.

PROPYLENE ROUTES
Both Dow and Braskem are interested in producing bio-based propylene. Kotanchek said Dow is investigating technology routes for the production of propylene and its derivatives, including acrylic acid and the acrylates chain. Bio-derived polypropylene (PP) is not a high priority, she noted, since the PP industry is relatively commoditized. Bio-based PE, on the other hand, is attractive because the PE industry is less commoditized and Dow's process technology for PE would enable the company to produce higher-value products, she said.

Dow does not intend to use ethanol as the raw material for its bio-derived propylene production, said Biggs. Selecting which process to use for converting the sugar to propylene is "the big question," he added.

Dow's bio-based propylene project will not necessarily be located in Brazil. The location depends on project technology and availability of feedstock, Kotanchek said. Selecting a location for a project will also involve identifying where there are shortages of propylene, the raw material for many of Dow's products, she added.

Dow has not revealed which process paths its R&D teams are investigating, although Kotanchek noted syngas was a possible route.

Braskem appears to be taking a different approach: it intends to convert sugarcane ethanol into propylene. The company announced plans in October 2010 to produce green propylene for the production of green PP. The green PP would be produced at one of Braskem's three Spheripol technology plants - one in Triunfo and the others in Paulinia and Maua in Sao Paulo state.

According to US-based consultancy Nexant, there are five main methods for the production of bio-based propylene (see flow diagram):

Fermentation of sugars to produce bioethanol, followed by dehydration to bioethylene. A portion of the ethylene is dimerized to produce normal butenes, which are reacted with the remaining bioethylene via metathesis to produce propylene;

Butanol is produced either by sugar fermentation or gasification of biomass and the bio-butanol is dehydrated to produce biobutene. The biobutene is reacted with bioethylene (as above);

Biopropane produced as a by-product of biodiesel production is dehydrogenated;

Vegetable oil is fed to an enhanced fluid catalytic cracker unit;

Gasification of biomass to produce a syngas is followed by synthesis of biomethanol. Methanol-to-olefins technology is then used to produce propylene.

NEXT GENERATION
Dow also plans to develop second-generation ethanol technologies. Brazilian sugarcane waste, known as bagasse, is the first priority, said Biggs, although the company could also look at alternative biomass sources such as wood chips.

"We're looking at cellulose to ethanol and trying to find the best technology combinations. One single technology alone is not going to be sufficient," he said.

In Brazil, bagasse is burned to provide energy both to power the ethanol mills and for export to the grid. "We believe that if the second-generation process can be made efficient enough, it will be more attractive to make ethanol than sell electricity," Biggs observed.

However, to make cellulosic ethanol value-creating in Brazil, it has to be extremely competitive, he added, because Brazilian ethanol is already the lowest-cost ethanol in the world.


By: Anna Jagger
+44 20 8652 3214



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