Abstract:

A Pt-CeO₂/AC catalyst was developed for the removal of high concentrations of formaldehyde (HCHO) in industrial exhaust under mild conditions. The HCHO removal was integrated into a N-(phosphonomethyl)glycine production process to remove in situ the high concentrations of HCHO in its exhaust stream. The HCHO produced and emitted (100-300 mg/m³) in N-(phosphonomethyl)glycine synthesis was completely removed by passage through the catalyst bed. The effects of temperature, space velocity, and HCHO content on removal efficiency were systematically studied. Almost all the HCHO was oxidized at gas hourly space velocities (GHSV) below 20000 h^-1, and the HCHO content was decreased to below 0.1 mg/m³, that is, the HCHO conversion rate was 99.10%-100%. When the GHSV was in the range of 30000-50000 h^-1 and the catalyst bed temperature was 12 ℃, the HCHO content in the treated gas was still less than 1.5 mg/m³, and the HCHO conversion rate was 97.56%-99.99%. The 1%Pt-4%CeO₂/AC catalyst is now in the pilot phase of its use in treating glyphosphate production exhaust gas containing high concentrations of HCHO, and good initial progress has been made. The concentrations of HCHO in the treated industrial exhaust were less than 10 mg/m³, which effectively has no HCHO health hazard, and there are good prospects for industrialization.

Key words: Platinum-ceria/activated carbon catalyst, Formaldehyde waste gas, Glyphosphate production, Formaldehyde removal