3000.     SABATIER, P., AND MAILHE, A.  [ Catalytic Decomposition of Formic Acid.]  Compt. rend., vol. 152, 1911, p. 1212-1215; Chem. Abs., vol. 6, 1912, p. 619.

        HCO₂H vapors were passed over 0.5 m. of the catalyzer at the rate of about 0.27 gm. per min.  The following catalyzers decompose the acid almost exclusively into CO₂ and H₂:Pd sponge, action begins at 110° and at 245° decomposition is virtually complete; Pt sponge, begins 120°, complete 215°; reduced Cu producers 278 cm.³ gas per min. at 190°; Ni, 290 cm.³ at 280°; Cd, 325 cm.³ at 280°; SnO begins above 150° and gives 172 cm.³ gas at 285°; ZnO begins about 190° and gives 192 cm.³ gas at 230°.  TiO₂ and W₂O₃ (blue) decompose the acid exclusively into CO and H₂O above 170°.  The same decomposition is produced by SiO₂, ZrO₂, Al₂O₃ and UO₂, but at the same time CO₂ is formed without H₂, indicating the decomposition of the acid into HCHO, CO₂, and H₂O; with Al₂O₃, the gas at 235° contains 6% CO₂; with UO₂ at 230°, 14% CO₂.  Some catalyzers effect all 3 of the above decompositions.  Thus, ThO₂ at 250° yields HCHO and a gas containing 75% (by vol.) of CO, 15% of CO₂, and 10% of H₂; at 320° the % of CO₂ increases to 45, and the condensed liquid contains CH₂ (OMe)₂ (owing to the formation of MeOH from HCO₂H and HCHO); as the temperature is raised, the amount of MeOH formed increases; and, as the HCHO is then partly decomposed into CO and H₂, the % of the latter increases and that of CO₂ decreases.  At 375°, the gas contains only 35% of CO₂.  The blue Mo₂O₃, CaO, FeO, and Jena glass produce chiefly the decomposition into CO₂ and H₂; ordinary white glass brings about this decomposition and that into CO and H₂O to about the same extent; the latter is predominant, with pulverized pumice, MgO, light wood charcoal, CrO₃, V₂O₃, MnO, and BeO.  These facts indicate that the action of the catalyzers cannot consist simply in lowering the temperature of reactions, which would take place without them; their chemical nature comes into play.