Alternative Routes to Chemical Methanol Products

Abstract

This chapter focuses on the syntheses of formaldehyde, formic acid/formate, acetic acid, which are alternative routes to the presently described industrial processes starting from methanol. In addition to the three industrial processes that oxidize methanol in HCHO, recent studies underline the attractive performances, which could be obtained with Mn2+-exchanged zeolite Y, and with titania in the oxidative dehydrogenation of methanol. It is possible to make the hydrogenation of carbon monoxide catalyzed by RuNi nanoparticles dispersed on γ-Al2O3 with a 19.14% conversion of CO and a 100% selectivity in HCHO, Formic acid can be obtained by the reaction of CO with methanol in basic medium; a new process uses the [RuCl2(PTA)4] complex, containing the water-soluble 1,3,5-triaza-7-phosphaadamantan PTA phosphine ligand, to catalyze the hydrogenation of CO2. With hydrothermal wet methods, catalytic oxidation reactions allow the transformation of biomass products into formic acid or sodium formate. Photo- and electro-catalysis is extending this formic acid production. In addition to the industrial synthesis of acetic acid by Rh-' or Ir-catalyzed methanol carbonylation, significant amounts are obtained by n-butane oxidation in the liquid phase. Other processes such as oxidation of acetaldehyde, ethylene, or ethane, and even biomass, and bacterial production are of interest. Electrocatalysis for biomass oxidation and water electrolysis, providing acetic acid and formic acid, is also attractive. A cobalt-phtalocyanine complex allows using CO2 as a CO surrogate to carbonylate methanol to acetic acid. Cu and Zn-based catalysts can provide CH3COOH from CH4 and CO2. The CeO2-HZSM-5 catalyst provides the possibility to perform the simultaneous hydrogenation of CO2 and the oxidative methane carbonylation in acetic acid.