| Formaldehyde is a hazardous, self-reactive, and costly chemical that traditionally has been avoided in chemical synthesis. However, a number of important chemicals, such as methyl methacrylate and styrene, could be produced more safely and with much less pollution from formaldehyde than by their current commercial processes. This research introduces the concept of in situ generation of formaldehyde, i.e., the generation and consumption of formaldehyde in the same reactor, so that there is no net production.;Methanol dehydrogenation to formaldehyde was studied in a slurry reactor at temperatures below 673 K over four different catalysts: Raney copper, copper chromite, 3% Mn on copper chromite, and FeTi alloy. The three copper-based catalysts were very effective at promoting methanol dehydrogenation. The FeTi catalyst did not perform as well as the three copper catalysts on a weight-of-catalyst basis, but was comparable on a surface-area basis.;Methanol dehydrogenation to formaldehyde was near equilibrium for the three copper-based catalysts at 598 K. The formaldehyde concentration is as high as chemical equilibrium will permit, so side reactions, such as formaldehyde dimerization to methyl formate and formaldehyde decomposition to carbon monoxide, are favored. The formation of methyl formate is not a serious negative, because methyl formate may serve as a reservoir of formaldehyde. The formation of CO is a more serious negative. However, no CO is formed at space velocities above 18000 sL/kg cat-hr.;Kinetic models have been developed for methanol dehydrogenation to formaldehyde and formaldehyde dimerization to methyl formate. With Raney copper, methanol dehydrogenation behaved as a second-order reversible reaction. Formaldehyde dimerization to methyl formate behaved as a second-order irreversible reaction. |
