Search

Zr-doped titania of anatase structure type has been prepared by a combined sol–gel and chemical vapour deposition (CVD) process. The material has been characterized by XRD, TEM and chemical analysis. The photocatalytic performance has been investigated in the oxidative decomposition of the pharmaceutical ibuprofen (IBP) down to low ppm concentrations. The change of the composition of the reaction solution after photocatalytic treatment was followed by UV–Vis spectroscopy and GC/MS. Formation of reaction intermediates was studied by HPLC coupled electrospray ionization time-of-flight mass spectrometry ESI-TOF-MS. The catalytic performance has been studied by varying the catalyst and substrate concentration as well as changing the catalyst-to-substrate ratio. The influence of pH, adsorption and re-use of the catalyst has been tested. The results confirm the high catalytic activity of Zr-doped titania compared to pure titania at low catalyst loading. The material shows the improved textural mesoporosity. However, more reaction intermediates were formed, leading to faster deactivation of the photocatalyst. ESI-TOF-MS measurements point to the formation of a couple of reaction intermediates, which poison the catalyst.

Current views of the mechanism of the catalytic isomerization of α-pinene were discussed. Catalytic systems, modifiers, process conditions, and the effect of process conditions on catalytic activity and on the target-product (camphene, dipentene) selectivities of the process were considered. α-Pinene isomerization was investigated over a Belarussian natural aluminosilicate (Al-Si RB), its derivatives modified with HCl and H3PO4, modified diatomite (Al/Dia), and bentonite (ZSM-5/Ben). The commercial aluminosilicate catalyst AS-36 was used as a reference sample. Al-Si RB was treated with 10% HCl (50–250 ml/g) or 10% H3PO4 (50–100 ml/g) at 50°C for 3 h. α-Pinene was isomerized in a round-bottom flask with a backflow condenser under flowing nitrogen. The rotational speed of the stirrer was 10 rps. The highest catalytic activity and the highest camphene selectivity were observed for Al-Si RB treated with 50 ml/g of HCl. With activated Al-Si RB and As-36, 85% α-pinene conversion at 130°C and a catalyst concentration of 0.5 wt % was attained in 5.5 and 7 h, respectively. The camphene selectivity for Al-Si RB treated with 50 ml/g of HCl was 61%, being ∼20 and ∼10% higher than in the case of AS-36 and Al/Dia, respectively. Al-Si RB retained its catalytic activity for 70 h and could be fully regenerated with acetone.

The preparation of nanoporous materials with enhanced stability using an improved synthesis route using reactive inorganic silica and alumina species is reported. This way improved mesoporous molecular sieves were obtained. The synthesized aluminum substituted mesoporous molecular materials (Al-MMS) contain very large pores of 50–200 A size combined with an improved pore wall thickness. Increased wall thickness and Al substitution lead to an improved chemical stability against alkaline solution. The textural, structural and acid properties are investigated by physico-chemical methods. The catalytic performance acidic materials was tested in the benzoylation reaction; amino functionalized materials were studied in the base catalyzed Michael addition.

A highly active photocatalyst based on Fe doped nano-sized TiO2 was successfully synthesized by chemical vapor deposition (CVD) using FeCl3 as iron source. The CVD was carried out by evaporating FeCl3 at 350 °C in nitrogen flow. The samples were characterized by AAS, XRD, XPS, UV-vis and FTIR. The photocatalytic activity of samples with different Fe contents obtained after different treatment times were tested in the oxidation of i-propanol in liquid phase using visible light. Titania and high Fe loaded TiO2 samples showed very low photo catalytic activity. In contrast, low loaded Fe doped TiO2 sample exhibited high photo catalytic activity. The high catalytic activity of this sample could be related to the presence of lattice defects (Ti-OH groups).

Novel nano-structured materials: nano-particle materials like V-SiO2, TiO2 and nano-sized pore materials like Si-MCM-41, Ti-MCM-41 and Al-MCM-41Analogues were successfully synthesised using different methods: precipitation, sol-gel, micro-emulsion and hydrothermal treatment. These obtained nano-structured materials were characterised by using different physico-chemical methods: FE-SEM, TEM, XRD, IR, UV-vis and nitrogen adsorption/desorption (BET). These materials were examined to investigate adsorptive and catalytic properties of the materials. Nano TiO2 exhibited highly photocatalytic activity in the degradation of methyl red (MR). Pure silica form MCM-41 (Si-MCM-41Analogue) was a selective absorbent for VOCs (m-xylene) removal. Ti substituted MCM-41Analogue exhibited highly photocatalytic activity in the degradation of red phenol (RP) while Al substituted MCM-41Analogue showed high catalytic cracking of petroleum residue (Bach Ho oil field – Vietnam). The obtained results are discussed and rationalised.