I think it’s remarkable how rapidly the chemical industry and, in particular, small startup firms, have responded to a consumer and bottled water manufacturers’ demand for the development of bottles made from renewable feedstocks. An article in the March 12-18 issue of ICIS Chemical Business provides extensive details. Clear plastics polyester bottles have ben traditionally produced from purified terephthalic acid (PTA) and monoethylene glycol(MEG). Both Coca -Cola and Pepsico have been pushing for bio-based raw materials for some time, in line with their sustainability policies. As a first step, Coca-Cola started making its Plantbottle using MEG produced from sugar cane. The more difficult part is to make PTA from renewables, but several firms are quickly rising to the challenge.
Virent will produce a sugar-based aromatics stream by a process involving so-called Aqueous Phase Reforming, followed by conventional catalytic processing to make p-xylene (the traditional feedstock), which is then converted to TPA in the usual manner. Gevo is pursueing an entirely different approach that converts fermentation-derived isobutanol to p-xylene, using dehydration, dimerization and cyclization. Other firms are researching different routes.
What remains to be seen are the economics of these and perhaps other routes to TPA. The problem, common for a new technology, is that existing (hydrocarbon-based) plants are huge, producing hundreds of million of pounds of MEG and TPA per year at correspondingly low cost. The new technologies need to be commercialized and then scaled up by several orders of magnitude to be economically competitive ….unless, of course, consumers are willing to pay extra for water in bottles made of renewable feedstocks – this remains to be seen.
Interestingly, Toray, a leading Japanese polyester manufacturer is cooperating with Gevo to produce bio-based textiles. This is an even larger market than that for PTA bottle resins.
China is arguable the largest polyester producer in the world and must now be looking hard at eventually replacing its hydrocarbon-based raw materials with renewable feedstocks as the development of technologies such as those described above advance.