Low-temperature selective oxidation of methanol over Pt-Bi bimetallic catalysts

Abstract

Formaldehyde is industrially produced by methanol selective oxidation over supported Ag or Mo-Fe catalysts in the temperature range 250–600 °C. The development of relatively low temperature processes for formaldehyde production is of importance to decrease energy costs and capital investment resulting from the high temperature operation. In the present work, various Pt-Bi bimetallic catalysts were designed, prepared, characterized and tested for low temperature (70–120 °C) methanol selective oxidation to formaldehyde. The highest selectivity toward formaldehyde (98.1%) at methanol conversion (8.1%) was achieved over the 1% Pt–0.5% Bi/AC (activated carbon) catalyst. Utilizing various characterization techniques (BET, EDX, H2-O2 titration, H2-TPR, ICP-AES, TEM, TPO, XPS and XRD) along with catalytic activity tests, the properties and performance of Pt-Bi bimetallic catalysts were correlated. The reducibility of Pt-Bi catalysts shows a linear relationship with formaldehyde selectivity, while methanol turnover frequency (TOF) values are essentially constant. Considering methanol as a simple molecule probe, the present work offers potential opportunities for selective oxidation of other alcohols at relatively low temperatures.