2-propanol In Gas Phase Research Articles

Photodegradation of 2-propanol in gas phase over zirconium doped TiO2: Effect of Zr content

The photocatalytic activity in the 2-propanol degradation, under UV and sunlight (SL)-type irradiations, of a series of Zr-TiO2materials, prepared using the sol–gel method, with a Zr content ranging from 0.25 to 1 wt%, was evaluated in this work. The physicochemical properties of the solids were characterized using X-ray diffraction, BET and porosity measurements, IR, UV–vis, Photoluminescence and X-ray photoelectron spectroscopy. The XRD data showed that the TiO2 was stabilized as anatase phase in all the samples and that the incorporation of Zr4+ into TiO2 lattice has led to a decrease of the crystallite size. The BET analysis confirmed that the addition of zirconium onto TiO2 support affected the surface area which increases with the increase of Zr4+ content. The UV-DRS spectra showed that, the incorporation of zirconium into TiO2 lattice leads to a slight decrease of the band gap energy of TiO2. The results of the photocatalytic test showed an enhancement on the photocatalytic activity of TiO2, in the 2 propanol degradation, by the doping with a low amount of zirconium. All the samples were found more active under UV illumination than under SL. In all cases, the highest efficiency in the 2-propanol photodegradation was observed for the 0.5% Zr-TiO2 sample and was essentially related to its lowest optical band gap energy.

Photocatalytic properties of TiO2-loaded porous silica with hierarchical macroporous and mesoporous architectures in the degradation of gaseous organic molecules

As an advanced support of TiO2 photocatalyst, mesoporous silica (MS) with hierarchical macroporous architecture (MMS) was prepared by applying templating synthesis techniques. Colloidal crystal of spherical poly(methyl methacrylate) (PMMA) particles and organic surfactant was used for construction of two types of pores with different size scales. The porous structure and state of TiO2 was investigated by various characterization techniques. Mesoporous and macroporous structure of MMS with interconnecting networks was maintained even after loading of TiO2 particles. The unique properties of macroporous structure were observed in the adsorption of acetone gas and 2-propanol gas. In comparison of TiO2-loaded MMS and MS (denoted as TiO2/MMS and TiO2/MS), TiO2/MMS showed a high adsorption rate and a large adsorbed amount in the case of 2-propanol at low and high relative pressure, respectively. However, each profile in the case of acetone was almost same in both samples. Based on the advantageous porous structure, TiO2/MMS also exhibited a good photocatalytic performance in the degradation of 2-propanol in gas phase under UV light irradiation.

Fabrication of Bi2O3/TiO2 nanocomposites and their applications to the degradation of pollutants in air and water under visible-light

A nanoheterojunction composite photocatalyst Bi2O3/TiO2 working under visible-light (λ ⩾ 420 nm) was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2 molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2 nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3.

Synthesis of Co3O4/WO3 Nanoheterojunction Photocatalyst for the Decomposition of Organic Pollutants Under Visible Light Irradiation

A highly efficient and visible light (k C 420 nm) responsive nano- composite photocatalyst Co3O4/WO3 was developed by dispersing p-type semi- conductor Co3O4 on the surface of n-type semiconductor WO3. The heterojunction Co3O4/WO3 demonstrated higher photocatalytic activity than WO3 ,C o 3O4 and TiO2 nanoparticles for the complete decomposition of 2-propanol in gas phase and phenol in aqueous phase and evolution of CO2 under visible light irradiation. The highest photocatalytic efficiency of the composite Co3O4/WO3 was observed when calcined at 300 C for 2 h with 4.91 mol% Co3O4/WO3. The enhanced photocat- alytic efficiency of the heterojunction was discussed based on the unique relative energy band positions and profound absorption of visible light by the semiconductors.

FTIR study of photocatalytic degradation of 2-propanol in gas phase with different TiO2 catalysts

The photocatalytic efficiency of different TiO2 catalysts in the degradation of 2-propanol in gas phase has been studied. The obtained efficiencies have been compared considering the distribution of rutile–anatase phases, surface area, particle size, distribution of surface hydroxyl groups and Brönsted or Lewis acid centres. The catalysts used were Degussa-P25 (TiO2-P25), Hombikat, Millennium, Kemira and s/g-TiO2, a catalyst prepared by a sol–gel method.The best photocatalytic behaviours have been obtained with those catalysts with higher surface area and the presence of only anatase phase (Hombikat and Millennium). A progressive deactivation of TiO2-P25 and s/g-TiO2 has been observed during the photocatalytic process.FTIR studies indicated that degradation mechanisms depended on the catalyst employed. Deactivation processes observed in TiO2-P25 have been correlated with the formation of carboxylates.

Efficient decomposition of organic compounds with FeTiO3/TiO2 heterojunction under visible light irradiation

FeTiO3/TiO2, a new heterojunction-type photocatalyst working at visible light, was prepared by a simple sol–gel method. Not only did FeTiO3/TiO2 exhibit greatly enhanced photocatalytic activity in decomposing 2-propanol in gas phase and 4-chlorophenol in aqueous solution, but also it induced efficient mineralization of 2-propanol under visible light irradiation (λ≥420nm). Furthermore, it showed a good photochemical stability in repeated photocatalytic applications. FeTiO3 showed a profound absorption over the entire visible range, and its valence band (VB) position is close to that of TiO2. The unusually high photocatalytic efficiency of the FeTiO3/TiO2 composite was therefore deduced to be caused by hole transfer between the VB of FeTiO3 and TiO2.

Photocatalytic Properties of Mesoporous TiO<sub>2</sub> Films Derived from Evaporation-Induced Self-Assembly Method

Hexagonal and cubic mesoporous TiO2 films were prepared by using triblock copolymer-templated sol-gel method via evaporation-induced self-assembly (EISA) process. The mesophase of TiO2 film was controlled by spin-speed during the spin-coating process. The hexagonal mesoporous structure was formed at a high spin-speed around 2000 rpm, whereas the cubic mesostructure was formed at a low spin-speed around 600 rpm. XRD and TEM results indicate that those mesostructures are highly organized with a pore diameter of 7 nm. The prepared cubic and hexagonal mesoporous films were tested as photocatalysts for the decomposition of 2-propanol in gas phase. Both films presented considerably higher photocatalytic activity than a nonporous TiO2 films prepared by a typical sol-gel process without addition of triblock copolymer. Notably, we found that the cubic mesoporous films showed a relatively higher photocatalytic activity than the hexagonal mesostructured film. We believe this is due to the orientation of pore channels open on the surface of mesoporous films.

Preparation of a visible-light-active TiO2 photocatalyst by RF plasma treatment

In order to realize a visible (vis)-light-active TiO2 photocatalyst, reduction treatment using low-temperature hydrogen plasma with elevated temperatures was applied on anatase TiO2 powder of ST-01 without causing a phase transition to rutile. According to plasma-heat treatment, oxygen was evacuated from ST-01 particles and the colored ST-01, ivory to beige, was obtained. XPS results showed non-stoichiometric, expressed as TiO2−x } and x was increased with the increase of treating time. Plasma-heat treated ST-01 showed new ESR signal at g = 2.003 assigned to electrons trapped at the oxygen-defect site. This signal was strengthened when vis-light illumination was applied. Results of vis-light activity tests, evaluated by photocatalytic oxidation of benzoic acid in liquid phase and 2-propanol in gas phase using vis-light illumination (>406 nm), showed excellent activity while low ST-01 showed almost no activity on both tests.