甲基膦酸二甲酯蒸气在TiO(2)表面的吸附与光降解

Adsorption and photodegradation of dimethyl methylphosphonate vapor at TiO(2) surfaces.

作者信息

Moss John A, Szczepankiewicz Steven H, Park Eleanor, Hoffmann Michael R

机构信息

W. M. Keck Laboratories, California Institute of Technology, Pasadena, California 91125, USA.

出版信息

J Phys Chem B. 2005 Oct 27;109(42):19779-85. doi: 10.1021/jp052057j.

DOI:10.1021/jp052057j

PMID:16853558

Abstract

The adsorption and degradation of the nerve agent simulant dimethyl methylphosphonate (DMMP) over UV-irradiated TiO(2) powders and thin films has been investigated. Adsorption of vapor-phase DMMP on TiO(2) powder is characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Photochemically assisted oxidation of adsorbed DMMP is carried out in situ by irradiation of samples in the DRIFTS accessory, giving kinetic data and information on specific site binding of DMMP and catalyst poisoning. Gas-phase intermediates from a static vapor phase reaction are identified by gas chromatography-mass spectrometry analysis, and surface-bound intermediates and products are analyzed by high-performance liquid chromatography-mass spectrometry, and ion chromatography of both aqueous and organic extractions from the TiO(2). Adsorbed DMMP is photodegraded in a stepwise fashion to give methylphosphonic acid, PO(4)(3-), H(2)O, and CO(2) as products. A proposed reaction pathway is consistent with a rapid degradation of DMMP but with extensive poisoning of the catalyst by surface-bound phosphonate products.

摘要

已对紫外线照射的二氧化钛粉末和薄膜上神经毒剂模拟物甲基膦酸二甲酯（DMMP）的吸附和降解进行了研究。通过漫反射红外傅里叶变换光谱（DRIFTS）对气相DMMP在二氧化钛粉末上的吸附进行了表征。通过在DRIFTS附件中照射样品，对吸附的DMMP进行光化学辅助氧化，给出动力学数据以及有关DMMP的特定位点结合和催化剂中毒的信息。通过气相色谱 - 质谱分析鉴定静态气相反应产生的气相中间体，并通过高效液相色谱 - 质谱以及对二氧化钛的水相和有机萃取物进行离子色谱分析表面结合的中间体和产物。吸附的DMMP以逐步方式进行光降解，生成甲基膦酸、PO(4)(3-)、H(2)O和CO(2)作为产物。提出的反应途径与DMMP的快速降解一致，但表面结合的膦酸盐产物会使催化剂大量中毒。