Experimental Study of Dimethyl Methylphosphonate Decomposition over Anatase TiO₂

Abstract

Removal from air and decomposition of dimethyl methylphosphonate (DMMP) over high surface area anatase TiO(2) at ambient temperature have been quantitatively studied by employing Fourier transform infrared (FTIR) technique under static conditions. In the first scenario of air purification, DMMP underwent reactive adsorption that upon completion was followed by photocatalytic oxidation. DMMP was captured over the TiO(2) surface at the speed of external diffusion. Hydrolysis of adsorbed DMMP led to methanol and methyl methylphosphonate (MMP). At low DMMP coverage quantity, it hydrolyzed completely with the formation of completely surface-bound methanol at 1% relative humidity (RH) and mostly gaseous methanol at 50% RH. Photocatalytic oxidation generated CO(2) as the only carbonaceous gaseous product and bidentate formates as the intermediate surface product. At high DMMP coverage quantity, it was captured incompletely and hydrolyzed partially with CH(3)OH in the gas phase only, 50% RH enhancing both processes. Photocatalytic oxidation generated gaseous HCOOH, CO, and CO(2) and was incomplete due to catalyst deactivation by nonvolatile products. In the second scenario of air purification, DMMP underwent adsorption, hydrolysis, and photooxidation at the same time. It resulted in the quickest removal of DMMP from the gas phase and completion of oxidation in 30 min, suggesting this process for practical air decontamination. At least 0.8 nm(2) of TiO(2) surface per each DMMP molecule should be available for complete purification of air.

Effects of F doping on TiO2 acidic sites and their application in QCM based gas sensors

“…New bands centered at 1730 cm −1 , 1686 cm −1 and 1535 cm −1 were observed simultaneously with the Lewis acid site adsorption on F-TiO 2 , but not observed on TiO 2 . Although previous works [24,25,31] mentioned some similar bands in context with DMMP dissociation and photocatalytic oxidation, those results do not meet the circumstance in the current work and the bands are not well fitted. Since no illumination was applied in the current work, the most possible reaction occurred would be the decomposition of DMMP on F-TiO 2 .…”

Adsorption and Decomposition of CWA Simulants on Single Crystal and Nanostructured Metal Oxides

“…The only precedence for complete oxidation of DMMP by molecular oxygen at room temperature on TiO 2 involves the use of UV radiation to produce conductionband electrons, which activate the oxygen. [3][4][5] In this study, we observe the production of similar products, but in the dark and at room temperature.…”

“…The broad band at ~ 1560 cm -1 suggests the formation of formate or carboxylate on Au-TiO 2 . [2][3][4][5] In addition, bands around 2100 cm -1 show that the Au-TiO 2 is active enough to form surface-bound carbon monoxide, a clear indication of the DMMP oxidation. 3 In contrast, no CO bands have ever been detected on pure-TiO 2 following DMMP exposure in the absence of UV radiation.…”

Tungsten oxide: a catalyst worth studying for the abatement and decontamination of chemical warfare agents

“…A valid alternative to these conventional chemical abatement strategies is the use of heterogeneous catalysts for the selective oxidation of CWAs into partially or fully oxidised non-toxic (or far less toxic) products (Bromberg, Creasy, McGarvey, Wilusz, & Hatton, 2015;Jang, Kim, Tsay, Atwood, & Churchill, 2015;Oudejans et al, 2016;Smith, 2008;Wagner, 2011Wagner, , 2015 Prasad et al, 2011;Trubitsyn & Vorontsov, 2005).…”