Saturday, October 13, 2012

Plastics Without Oil.

Crude oil provides the principal source of carbon for the whole of the chemical industry, to fabricate products ranging from plastics to pharmaceuticals. However, oil is a finite resource, and predictions from the Energy Information Administration (EIA) are that the world supply of crude oil may begin to fail demand for it within a year, which is in accord with studies from both the U.S. and German military. p-Xylene is a raw feedstock for the polyester industry, and is produced by catalytic reforming of petroleum naphtha. p-Xylene is oxidized to form terephthalic acid, which by condensation with ethylene glycol forms polyethylene terephthalate, of which some 5 million tonnes annually is manufactured. A process is under development for making polyesters which is independent of crude oil, since it uses ethylene as its feedstock. First, a trimer molecule, containing 6 carbon atoms, is formed from ethylene. Following dehydrogenation, this material undergoes a Diels–Alder reaction with an additional ethylene molecule to form 3,6-dimethylcyclohexene. By dehydrogenation of the latter material, using a platinum catalyst supported on alumina, a good yield of p-xylene is obtained, with minimal side-products, so obviating the need for complex, energy-intensive separation processes. In contrast to cracking light hydrocarbons from oil at high temperatures to form ethylene, it might instead be generated from biomass, and thus this development might be perceived as a first step on the path to the extrication of an industry from its utter dependency on crude oil. In the medium term, ethylene can be made from Natural Gas Plant Liquids, or even shale gas.

Friday, October 12, 2012

Soil and Phosphorus.

I have just submitted the following letter to RSC News, which is published by the Royal Society of Chemistry.


The quality of soil cannot be over-emphasised, as was alluded to in the September issue of RSC News, and indeed pointed-out in 1937 by the then U.S. president, Franklin D. Roosevelt, in a letter to State Governors saying that: “The nation that destroys its soil destroys itself," urging uniform soil conservation laws. Roosavelt was aware too of the importance of phosphorus in soil, though the agriculture in the U.S. was far less dependent on rock phosphate as a fertilizer, and indeed the rest of the world, than is the case now. According to some estimates, the production of rock phosphate will peak around the year 2030, with potentially catastrophic consequences for world food production in the subsequent years. A wholesale conservation of phosphorus is necessary, including from human and animal waste, to allay this situation, and methods of regenerative agriculture and permaculture should be researched and developed which both reduce inputs of synthetic and mined fertilizers, and rebuild the organic component of soil, including its mycorrhizal fungi, which act symbiotically with the roots of plants, and provide nutrients (including phosphate) to the plants in exchange for carbohydrate delivered from the plant as formed by photosynthesis. As a rider to this, the excessive application of phosphate fertilizer discourages the growth of the fungi, and renders agriculture yet further dependent on artificial inputs of phosphorus, in a pseudo-addictive fashion. It has been stated that, if done over the world's 15 million square kilometers of arable land, some 40% of anthropogenic carbon emissions might be sequestered in soil through the implementation of regenerative practices.


Chris Rhodes