The Chemistry and Engineering Challenges in the Conversion of C1 Molecules

As with comets and eclipses, the wish to convert C1 molecules to chemicals and fuels recurs for each generation. Such cycles bring us today, once again, to matters of chemistry and engineering inherent in converting molecules lacking C-C bonds (e.g., methane, methanol, dimethyl ether) into more useful products. The conversion of these C1 molecules (especially CH4) imposes formidable thermodynamic and kinetic hurdles, as well as unavoidable complexity and cost, into the practice of the requisite chemical transformations. The selection process by which we choose the most appropriate path to target products is fraught with distracting detours; there are, however, fundamental principles and concepts that guide us.

The signposts along the way remind us that: (i) catalysts cannot circumvent thermodynamics and, only imperfectly, how the energy of chemical bonds influences their tendency to react; (ii) process simplicity and inexpensive oxidants “trump” the glamour of more direct conversions; (iii) kinetic and thermodynamic protection strategies and cyclic schemes are clever, but often costly; (iv) the coupling of reactions and separations (or of several reactions) is elegant at the chemical nanoscale, but typically  practical only at the length scales of mass and energy transfer; (v) success at forming the first C-C bond is only the start of our worries; and (vi) when seeking to activate stronger C-H bonds instead of weaker ones, mild manners are neither virtuous nor profitable. This lecture aims to chart a roadmap and to illustrate how roadmaps can guide us in tackling scientific and engineering challenges.