On-Demand Generation of a Formaldehyde-in-Air Standard.
The feasibility of using catalytic conversion of methanol to formaldehyde to produce standard amount of substance fractions of formaldehyde was examined. The conversion efficiencies of several catalysts were measured as a function of temperature, balance gas, catalyst bed length, and methanol amount of substance fraction in an effort to identify conditions which yield high and consistent conversion of methanol to formaldehyde. The highest observed conversion rate was (97 ± 4) % using a molybdenum catalyst, where the error is the 2σuncertainty. The conversion efficiency was found to be consistent over repeated cycles and over a long lifetime test, suggesting that a molybdenum catalyst is a viable candidate for a standard formaldehyde generator, particularly for low formaldehyde amount of substance fractions (< 15 μmol/mol).
National Institute of Standards and Technology, Gaithersburg, MD 20899-0001.
P M
PM
Chu
National Institute of Standards and Technology, Gaithersburg, MD 20899-0001.
W J
WJ
Thorn
National Institute of Standards and Technology, Gaithersburg, MD 20899-0001.
R L
RL
Sams
National Institute of Standards and Technology, Gaithersburg, MD 20899-0001.
F R
FR
Guenther
catalytic conversion of methanol; formaldehyde; formaldehyde standard; gas standards; vehicle emissions