Chemical reactions require energy to take place. Starting molecules with a high chemical energy content are converted into low-energy products. The linking of an energy-consuming target reaction with an energy-yielding accompanying reaction through the use of high-energy, ecologically and economically suboptimal reagents is typical in syntheses, with "used" molecules being disposed of as waste, e.g stable salts, which cannot be recycled or are very energy-intensive. A textbook example is the vitamin A synthesis by BASF, in which stoichiometric amounts of triphenylphosphine oxide are produced in a Wittig reaction, which is chlorinated with highly toxic phosgene and, by reduction with aluminum is recovered to form the basic building block triphenylphosphine required for the process.
Although such processes are widely established in the chemical industry and represent the backbone of chemical production, there is a need to rethink chemical production towards nuclear and energy economical processes while avoiding fossil energy sources. Many chemical products will continue to be manufactured from fossil raw materials in the future; Oil and natural gas remain important sources of carbon, but renewable non-edible raw materials, such as cellulose and lignin, and in coupled processes can also be expanded to include the carbon dioxide produced in chemical production in combination with regenerative energies.
However, there are considerable obstacles to the changeover from established processes in the chemical industry considering the associated investments and adjustments to the infrastructure, which is why innovations often do not exploit their full potential for transfer to industrial chemical processes. PEC ideally combines pre-competitive, application-oriented basic research with the latest research that is still at an academic level with practical challenges of industrial implementation.