Green Chemistry for Polymers

In the long-term industry will have to find substitutes for fossil fuels as supplies diminish and costs rise: so what is a sustainable resource for synthesis of conventional plastics? At Green Polymer Chemistry 2012 in Cologne, Germany, AMI brought together experts from agriculture, chemical engineering, biotechnology, the polymer industry and sustainability managers from brand owners and the automotive sector to hear all the angles on this topic. LMC International studies the agricultural including sugar, grains and oilseeds. Worldwide, corn wheat and cassava accounted for 1.7 billion metric tonnes in 2010/11, and sugarcane and sugar beet generated 160 mln tons (the lead producer is Brazil). On the vegetable oil side, palm predominates at 48 mln tos (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. 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 mln 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. Dr Jan Kees Vis at Unilever has been involved in projects such as the Sustainable Palm Oil roundtable; the aim of this brand owner is to double “the size of our company while reducing our environmental impact”. The automotive industry is also pushing forward in this arena. The Ford Motor Company 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. 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 200kty and 30kty respectively. 86.5 tons of sugar cane gives 7200 litres of ethanol and 3 tonnes of polyethylene. 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. Biomass production amounts to 165 billion tpa, 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 4 tonnes of straw yields 1 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. It 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. Greencol Taiwan (JV of CMFC and Toyota Tshuho) has taken technology to produce monomers for bio-PET and the new plant is due to start up in 2012. There has been great progress towards production of fully bio-based PET. Avantium has generated a “technical drop-in” for the terephthalic acid component from furan dicarboxylic acid synthesised by dehydration and oxidation from carbohydrates. The vegetable oil market in Germany amounts to 5.16 Mtons of rape seed, 50 ktons of sunflower, and imported sunflower, linseed, soybean (from USA), castor oil (India), palm and coconut oil (Malaysia, 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. 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 Royal DSM. The company 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.
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