Pyrolysis of pine and gasification of pine chars--influence of organically bound metals.

Pyrolysis of pine and gasification of pine chars was studied in this work, focusing on the influence of organically bound metals. Selective leaching of the major ash-forming elements in pine wood was performed with different acids, namely, nitric, sulfuric, hydrochloric and oxalic acids. No other major changes in the chemical composition of the biomass were observed except the removal of the metals. The effect of organically bound sodium, potassium, magnesium and calcium was studied in both pyrolysis and gasification. Removal of the metals had a positive effect on the pyrolysis, resulting in higher bio-oil, lower char and gas yields.

Evaluation of mesoporous TCPSi, MCM-41, SBA-15, and TUD-1 materials as API carriers for oral drug delivery.

The feasibility of four mesoporous materials composed of biocompatible Si (TCPSi) or SiO(2) (MCM-41, SBA-15, and TUD-1) were evaluated for oral drug delivery applications. The main focus was to study the effect of the materials different pore systems (unidirectional/2D/3D) and their pore diameters, pore size distributions, pore volumes on the maximal drug load capacity, and release profiles of a loaded active pharmaceutical ingredient. Ibuprofen was used as the model drug. The total pore volume of the mesoporous solid was the main factor limiting the maximum drug load capacity, with SBA-15 reaching a very high drug load of 1:1 in weight due to its high pore volume. Dissolution experiments were performed in HBSS buffers of pH 5.5, 6.8, and 7.4 to mimic the conditions in the small intestine. At pH 5.5 the dissolution rate of ibuprofen released from the mesoporous carriers was significantly faster compared with the standard bulk ibuprofen (86-63% versus 25% released at 45 min), with the fastest release observed from the 3D pore network of TUD-1 carrier. The utilization of mesoporous carriers diminished the pH dependency of ibuprofen dissolution (pK(a) = 4.42), providing an interesting prospect for the formulation of poorly soluble drug compounds.

Synthesis of Pt modified ZSM-5 and beta zeolite catalysts: influence of ultrasonic irradiation and preparation methods on physico-chemical and catalytic properties in pentane isomerization.

Influence of preparation methods and ultrasound irradiation on physico-chemical and catalytic properties was investigated by synthesizing Pt-ZSM-5 and Pt-Beta catalysts by in-situ and impregnation methods and applying ultrasound irradiation to synthesis gel mixture of ZSM-5 and Beta zeolites. It was concluded from the X-ray powder diffraction patterns of Pt-ZSM-5 and Pt-Beta zeolite catalysts that introduction of Pt by in-situ method and ultrasound irradiation did not influence the structures of ZSM-5 and Beta zeolites. Morphology of ZSM-5 and Beta zeolites were investigated by scanning electron microscopy. SEM micrographs showed that the Pt-ZSM-5-IS-US catalyst synthesized by in-situ method with ultrasound irradiation resulted in smaller crystals of ZSM-5 than Pt-ZSM-5-IS catalyst prepared without ultrasound irradiation. Furthermore SEM micrographs of Pt-Beta-11-IS-US zeolite synthesized using ultrasound irradiation showed much smaller crystals than Pt-Beta-11-IM indicating that ultrasound irradiation had a significant effect on the morphology of Beta zeolite. Conversion of n-pentane and selectivity to iso-pentane over the Pt-ZSM-5-IS-US zeolite catalysts prepared by ultrasound irradiation during in-situ introduction of platinum was higher than the catalysts prepared without the ultrasound irradiation. Furthermore ultrasound irradiated and in-situ synthesized Pt-Beta-11-IS-US catalyst also showed higher selectivity to iso-pentane than Pt-H-Beta-11-IM prepared by impregnation method.

Mesoporous silica material TUD-1 as a drug delivery system.

For the first time the feasibility of siliceous mesoporous material TUD-1 (Technische Universiteit Delft) for drug delivery was studied. Model drug, ibuprofen, was adsorbed into TUD-1 mesopores via a soaking procedure. Characterizations with nitrogen adsorption, XRD, TG, HPLC and DSC demonstrated the successful inclusion of ibuprofen into TUD-1 host. The amount of ibuprofen adsorbed into the nanoreservoir of TUD-1 material was higher than reported for other mesoporous silica drug carriers (drug/carrier 49.5 wt.%). Drug release studies in vitro (HBSS buffer pH 5.5) demonstrated a fast and unrestricted liberation of ibuprofen, with 96% released at 210 min of the dissolution assay. The drug dissolution profile of TUD-1 material with the random, foam-like three-dimensional mesopore network and high accessibility to the dissolution medium was found to be much faster (kinetic constant k = 10.7) and more diffusion based (release constant n = 0.64) compared to a mesoporous MCM-41 material with smaller, unidirectional mesopore channels (k = 4.7, n = 0.71). Also, the mesoporous carriers were found to significantly increase the dissolution rate of ibuprofen, when compared to the pure crystalline form of the drug (k = 0.6, n = 0.96). TUD-1 was constituted as a potential drug delivery device with fast release property, with prospective applications in the formulation of poorly soluble drug compounds.

Classification and pattern recognition of acyclic octenes based on mass spectra.

Two SIMCA models were developed for the classification of acyclic octene isomers, which only form a fraction of a very complex product mixture obtained, for example, from the transformation of 1-butene. The effects of spectral transformation, namely autocorrelation and logarithmic intensity ratios transforms, and (square-root) scaling of the octane isomers mass-spectral data were investigated. Both the spectral-features preprocessing methods and scaling were found to be vital for an adequate development and improvement of the classification models. The best SIMCA models were successfully applied on gas-chromatography-mass spectroscopy (GC-MS) analysis collected from the dimerization of 1-butene over heterogeneous catalysts in the liquid phase.

Analysis of the state and size of silver on alumina in effective removal of NOx from oxygen rich exhaust gas.

Ag/alumina catalysts with different silver contents for octane-SCR were prepared by impregnation and incipient wetness methods. Activity tests revealed that the decisive factor for high activity is not only a high dispersion of silver, but also the ability of the system to redisperse clustered silver. Determination of dispersion by TEM/HAADF and O2-chemisorption experiments resulted in values close to each other even if the results were not directly comparable. This is suggested to be due to not complete silver reduction below 700 degrees C and the samples being very heterogeneous in terms of particle size, e.g., having a bimodal size distribution. Small charged Agsigman+ clusters containing 2-8 silver atoms highly prevailed in the samples containing <2 wt% Ag and exhibiting high octane-SCR activity. In highly loaded Ag/alumina samples or those reduced and reoxidized at high temperature (>400 degrees C), large metallic particles are stabilized, resulting in poor conversion of NOx to N2.

Structure-activity relationship in HC-SCR of NOx by TEM, O2-chemisorption, and EDXS study of Ag/Al2O3.

Ag/alumina catalysts with different silver loading (1.28-6 wt %) for lean NO reduction activity were prepared by impregnation and the incipient wetness method. Complementary HRTEM, HAADF, O2-chemisorption, and EDXS studies were applied to investigate the dependence between silver particle size and catalytic activities of the prepared materials. The catalyst with the lowest silver loading (1.28 wt %) was found to be the most active catalyst in terms of reacted NO molecules per mole of silver. On the basis of the HRTEM, HAADF, and O2-chemisorption studies it could be concluded that the mean particle size or particle size distribution of the samples alone could not explain the big difference in the activities. EDXS analyses showed on the other hand that all of the samples were very heterogeneous in terms of particle size distribution, e.g., including both small and very big particles. Furthermore, both metallic silver and mainly hexagonal silver oxide (Ag2O) were found to be present in the samples. Despite the valuable information provided by ex situ characterization of the prepared samples, it needs to be emphasized that establishing a structure-reactivity relationship for this type of catalyst requires in situ characterization.

Effect of ultrasound in enantioselective hydrogenation of 1-phenyl-1,2-propanedione: comparison of catalyst activation, solvents and supports.

The enantioselective hydrogenation of 1-phenyl-1,2-propanedione was carried out over Pt/Al2O3, Pt/SiO2, Pt/SF (silica fiber), Pt/C catalysts modified with cinchonidine under ultrasonic irradiation. The initial rate, regioselectivity and enantioselectivity were investigated for different catalyst pretreatments, solvents and ultrasonic powers. The ultrasound effects were very catalyst dependent. The sonication significantly enhanced enantioselectivity and activity of the Pt/SF (silica fiber) catalyst. For the other Pt supported catalysts the reaction rate, enantioselectivity and regioselectivity increased moderately. The choice of solvent influenced the impact of ultrasound effect, namely in mesitylene, which has the lowest vapor pressure, the highest ultrasound enhancement was observed. The effect of sonication on catalysts surface was studied by transmission electron microscopy and scanning electron microscopy (SEM). No significant change in the metal particle size distribution due to sonication was observed. However, in the case of the Pt/SF catalyst, acoustic irradiation induced morphological changes on the catalyst particle surface (SEM), which might be the cause for enhancement of the initial reaction rate and enantioselectivity.