Green chemistry for polymers

Cologne, Germany – In the long-term industry will have to find substitutes for fossil fuels as supplies diminish and costs rise, including sustainable resources for synthesis of polymer materials.

At the recent Green Polymer Chemistry 2012 in Cologne, conference organisers AMI brought together experts from agriculture, chemical engineering, biotechnology, the polymer industry and sustainability managers from brand owners and the automotive sector to discuss progress in this arena.

For a market-size perspective, LMC International presented figures showing that worldwide, corn wheat and cassava accounted for 1.7 billion metric tonnes in 2010/11, and sugarcane and sugar beet generated 160 million tonnes (the lead producer is Brazil).

On the vegetable oil side, palm predominates at 48 million tonnes (85% is grown in Malaysia and Indonesia) and is unique in being harvested from trees each year - the other oils are from seeds.

The agricultural industry is already seeing a “battle for acres” globally, beleives LMC, noting that this began in 2002 with the drive to use bioethanol/biofuel, which increased demand for arable land for growing feedstock.

By 2010 the area under cultivation had expanded worldwide by 70 million hectares. Besides biofuels, there are other factors such as the rise in per capita income in Asia, which means that consumers are eating more meat thus increasing the demand for animal feed. More land can be cultivated from areas such as the Black Sea, South America and South East Asia if it is cost-effective.

Bio-based plastics and other fine chemicals are now being produced from agricultural feedstocks and the challenge is to find sources that are sustainable in this global marketplace. Brand owners and retailers have studied sustainable sourcing extensively, with all of the majors operating policies including Walmart, Carrefour and Tesco and Unilever.

For Unilever, Dr Jan Kees Vis at Unilever, who has been involved in projects such as the Sustainable Palm Oil roundtable noted that the company aims to double in size while reducing its environmental impact.

This includes a plan to source 100% of agricultural raw materials sustainably: palm oil is the top material at 1.4 million tonnes per annum primarily for surfactants, then paper, soy and sugar, followed by other oils.

Unilever has put together a Sustainable Agriculture Code and wants to use products with certification, such as Rainforest Alliance and Fair Trade.

There are many other issues such as the need to ensure the security of food supplies. Thus brand owners, such as Unilever will ask questions of suppliers about the sustainability, not just renewable sourcing, of new products.

The automotive industry is also pushing forward in this arena. Ford Motor Co. for example has some notable new developments in using renewable sources, such as soy polyol-based polyurethane foam, which cut CO2 emissions by 14.3 million tonnes.

One problem is the large number of cars produced, currently 4.8 million per annum, so any material specified must be available in considerable quantity.

In the case of soy, the United Soybean Board was keen to find a use for the oil as the bean was being grown for animal meal and oil was a side-product. There is also use of recycled materials and natural fibre reinforcements like hemp, sisal and wheat straw.

Ford is using a bio-TPU from Merquinsa Mercados Quimicos, now part of Lubrizol, which has a renewable source for the polyol component.

The Brazilian sugar cane industry is the largest in the world. Braskem has utilised this sugar as a source of feedstock to make its “green” polyethylene and polypropylene with current capacities at 200ktpa and 30ktpa respectively. 86.5 tonnes of sugar cane gives 7200 litres of ethanol and 3 tonnes of polyethylene.

Brazil has vast areas of arable land that could be used to develop this industry and Braskem is studying all aspects including ways to increase yield. The company uses BonSucro-certified ethanol. There have been several technology breakthroughs in the past year in producing substrate from cellulose – so-called second generation feedstock.

The M&G Group has PROESA Technology and built a pilot plant in 2009. This generates C5 and C6 sugars in a continuous process. The plant has been in operation for 400 days continuously and many enzymes and 15 types of biomass feedstock have been tested.

The Crescentino demonstration plant will have capacity for 40ktpa cellulosic ethanol and will generate 15MW of power from the lignin by-product to the grid, as well as selling the ethanol.

In Finland, meanwhile, the VTT Technical Research Centre has examined the feedstock potential of the country’s forests, where growth rate of trees is expected to rise by 25% in the next five years due to global warming. VTT has piloted the manufacture of ethanol from lignocellulose with UPM including recycled paper.

Biomethane can also be used in the olefin supply chain: methanol to olefins (MTO), ethylene and propylene was investigated by Mobil in the 1980s and Total Petrochemicals built a demonstration unit in Feluy in 2010. VTT has also experimented with wood oils and the manufacture of LDPE from tall oil.

Biomass production amounts to 165 billion tonnes per year, 50% cellulose and 24% hemi-cellulose. Sud-Chemie AG sees sugars as the new oil and has partnered with SABIC in the ‘sunliquid’ process, which takes lignocellulose feedstock and converts it to fermentable second generation sugars or ethanol, which can be used to make monomers for plastics like PE and PET.

Around four tonnes of straw yields one tonne of ethanol. The ‘sunliquid’ process works with different renewable feedstocks. The biggest potential source of lignocelluloses is rice straw in Asia at round 750 million tonnes. Sud-Chemie also has a Liquibeet technology using enzymes to liquefy sugar beet.

Petron Scientech was founded in 1991 in Mumbai and Princeton and has ethanol to ethylene technology with a high conversion rate around 100% with close to 99% ethylene selectivity.

Reactor design has to factor in the highly endothermic reaction and heat recovery. Petron Scientech has supplied technology to companies such as Oswal in India, which maximises use of sugar cane - sugar is sold, bagasse is sent to fuel power stations and the molasses is used to make industrial ethanol and from there to make polyethylene.

There has been significant progress towards production of fully bio-based PET. Avantium has generated a “technical drop-in” for the terephthalic acid component from furan dicarboxylic acid (FDCA) synthesised by dehydration and oxidation from carbohydrates. This FDCA can also feed into polyurethane and polyamides.

Partners in this work include Teijin, Coca Cola, Solvay, Rhodia and Danone. The PEF material has been tested on commercial blow moulding, fibre and film lines and has a higher gas barrier than PET. A pilot plant is being constructed at Chemelot in the Netherlands with capacity of 40 tonnes per year.

Greencol Taiwan, a JV between CMFC and Toyota Tshuho, has adopted technology to produce monomers for bio-PET, with a new plant is due to start up in 2012.

The Wageningen University has studied crops as chemical sources, looking at algae for fatty acids, dandelions for latex, and seaweed for biorefineries among many other projects. They have examined pathways to a wide range of biobased monomers including furans for polyamide and polyester production. Biocatalysis is the preferred technology with relatively mild reaction conditions.

Novozymes, which has the largest market share of industrial enzymes worldwide, sees renewable chemicals as a key to meet the demand from the growing world population, which is anticipated to reach 9 billion in 2050. This will move the renewable chemicals industry from “tech push to market pull”.

Current chemical engineering has been optimised for decades and the biotech industry needs to catch up and compete on cost and performance.

Genzyme has Cellic to produce ethanol from biomass at $2-2.5 per gallon and more competitive enzymes coming on stream now. The company is a partner in the M&G cellulosic ethanol plant and also involved in projects with Cargill, Braskem and ADM. The work with Cargill involves bio-acrylic acid production for applications from diapers to coatings and adhesives.

Another company to focus on the enzymatic routes to make monomers from renewable sources is Global Bioenergies. Its focus is on direct fermentation to give products such as propylene and butadiene.

Synthos is a partner in the latter project. The company develops possible synthetic pathways with corporate clients and uses databases of enzymes to find suitable catalysts for cloning in bacteria. A pathway to isobutene has already been established.

The use of more conventional catalysts has been reviewed by the Leibniz Institute for Catalysis, which has been studying the production of monomers from vegetable oils.

The vegetable oil market in Germany amounts to 5.16 million tonnes of rape seed, 50 ktonnes of sunflower, and imported sunflower, linseed, soybean (from the US), castor oil ( from India), palm and coconut oil (from Malaysia and Indonesia). These oils can be used in synthesis of polyurethane, polyester, polyamide, polyacrylate and epoxy resin.

For example, Emery Oleochemicals has achieved ozonolysis of oleic acid which can be used in polyamide 6.9; Evonik has chemical pathways for ricinoleic acid to give polyamide 10.10 and 6.10; Arkema has polyamide 11 from 11-undecanoic acid from castor oil, and BASF has made polyamide 6.10 and polyols from sources such as castor oil.

However, said AMI, the industry needs to become more competitive and this includes breeding strains of plant with higher levels of useful fatty acids, like high oleic sunflower oil. There is also potential to produce oils from bacteria or algae.

Several major chemical companies have prioritised sustainability including DSM, which is producing polyamide 410, thermoplastic copolyester and UP resin from bio-sources and comments that OEMs ask, “Is it competing with the food chain?”

Another factor is that like all renewable technology the price has to be comparable to existing products as the markets are not prepared to pay extra. The Biosuccinium project with Roquette to produce succinic acid in a yeast-based process is scheduled for large scale production (10kt) in Italy in 2012. There are also plans to make bio-based adipic acid, a precursor for polyamide 66.

Cathay Industrial Biotech based in China is the largest global producer of biobutanol with over 7 million gallons produced in 2011 and it is moving into lignocellulose technology. The company has also commercialised a polyamide 5 monomer from lysine via decarboxylation to pentamethylenediamine, which can be combined with a biobased di-acid.

One issue was bioprocess impurities, which represented a new challenge. The new monomer could be used in polyamide 5,10, 5,6, 5,4 or 5,X. The company is looking for partners to develop these materials.

There is a lot of interest in technology to synthesise polymers from carbon dioxide. Several companies worldwide are involved in the production of polypropylene carbonate including Bayer Material Science (BMS) and BASF in Europe, Novomer in the USA, SK Innovation in Korea, and Mengxi in China.

BASF is motivated by low monomer costs, reducing CO2 emissions trading and the abundant feedstock from power plants. It is testing the material in several applications such as an ABS replacement in electrical appliances, in agricultural films and in paper coatings. One issue is the low activity of catalysts and the need to remove the catalyst after polymerisation.

BMS has generated polyether-polycarbonate polyols from CO2 for use in polyurethane, as well as producing the plastic polypropylene carbonate. The CO2 supply is scrubbed at the coal-fired power plant and then reacted with propylene oxide. It has taken the company time to reduce the by-products and improve catalyst use towards its “dream production” target level. Slab stock foam has been produced and tested.

The biobased chemical industry for fine chemicals is moving toward reality. One driver is the changes in cracker operation that will reduce the supply of elastomer C4-C5 monomers.

The Materia Nova Institute has reviewed the research into building blocks for polymers, including succinic acid (DSM, Bioamber, Roquette, Mitsubishi Chemical), sorbitol (Cargill, ADM, Roquette), propylene (Braskem, DuPont/Tate & Lyle), butadiene (Goodyear, Lanxess, Michelin, Synthos, Genomatica) and caprolactam (Draths).

Solvay has a pilot plant to generate 60,000 tonnes of partly biobased PVC in Brazil as another example. Vincent Berthe speculates that the biobutanol platform could become bigger than bioethanol: it can be made directly by glucose fermentation.

The question of sustainability revolves around the competition for land and the impact on agriculture.

The NNFCC in York, UK, which has studied crops for non-food use for many years, noted that 40% of sugars and starch in the EU are already grown for other purposes than food.

John Williams at the not-for-profit consultancy, calculates that around 250-800 million hectares of land are available for crops for bioenergy and fine chemicals excluding forest, protected areas and land for increased food production.

The EU has renewable energy mandates that put pressure on the biomass supply chain, according to Williams. This, he said, makes predicting the future more difficult and 2030 and 2050 calculations are usually given based on several scenarios.

The NNFCC’s overall prediction is that bio-based plastics will reach around 1% of the market by 2020 at 3-5 million tonnes, up to 10% by 2030 at 43 million tonnes and to 20% of the market in 2050 at 155 million tonnes.