Alalwan Hayder, Alminshid Alaa
Department of Petrochemical Techniques, Technical Institute-Kut, Middle Technical University, Baghdad, Iraq.
Department of Chemistry, Collage of Science, Wasit University, Kut, Wasit, Iraq.
Spectrochim Acta A Mol Biomol Spectrosc. 2020 Mar 15;229:117990. doi: 10.1016/j.saa.2019.117990. Epub 2019 Dec 24.
In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has been used to investigate the adsorption and catalytic reaction of acetone on TiO surfaces. The adsorption of acetone has been investigated on hydrated (as-received from the provider) as well as dehydrated TiO nanoparticles. On both samples, acetone shows absorption bands results from the vibrational modes of acetone adsorbed molecules. The DRIFTS spectra indicate that acetone goes into a self-condensation reaction then it dehydrated yielding mesityl oxide. Formation of formaldehyde was observed only on as received sample and it was probably activated as a result to suppress mesityl oxide formation. This suppressed formation is a result of the existence of adsorbed HO on the surface of as received TiO. Adsorbed water is not favorable for aldolization/dehydration reaction because it can block the active sites for mesityl oxide formation. Outcomes of the current study provide fundamental insight into acetone adsorption and catalytic reaction on TiO nanoparticles. Specifically, this investigation demonstrates the adsorption mechanism of acetone on TiO surface and the role of presenting hydroxyl group on the TiO surface.
原位漫反射红外傅里叶变换光谱（DRIFTS）已被用于研究丙酮在TiO表面的吸附和催化反应。已对水合的（从供应商处原样接收）以及脱水的TiO纳米颗粒上的丙酮吸附进行了研究。在这两种样品上，丙酮都显示出由吸附的丙酮分子的振动模式产生的吸收带。DRIFTS光谱表明，丙酮发生自缩合反应，然后脱水生成异亚丙基丙酮。仅在原样接收的样品上观察到甲醛的形成，并且它可能因此被活化以抑制异亚丙基丙酮的形成。这种抑制的形成是由于原样接收的TiO表面上存在吸附的羟基。吸附的水不利于羟醛缩合/脱水反应，因为它会阻塞异亚丙基丙酮形成的活性位点。当前研究的结果为丙酮在TiO纳米颗粒上的吸附和催化反应提供了基本的见解。具体而言，本研究证明了丙酮在TiO表面的吸附机制以及TiO表面上存在的羟基的作用。
