Zeolites ZSM-5 (SiO2/Al2O3=30~280) and Y(SiO2/Al2O3=5.2~80) are bound with silica gel (Ludox HS-40 and Ludox AS-40) and alumina (γ- Al2O3 and boehmite) by different binding methods, namely, gel-mixing, powder-mixing and powder-wet-mixing methods. The acidities of the bound catalysts and the zeolite powder are determined by NH3-TPD and FTIR. The textures of these catalysts are analyzed on a BET machine with nitrogen as a probe molecule. The micropore surface area and micropore volume are determined by t-plot method. Micropore volume distribution is determined by Horvath-Kawazoe approach with a cylindrical pore model. Mesopore volume distribution is determined by BJH method from the nitrogen desorption isotherm. Silica from the binder may react with extra-framework alumina in zeolites to form a new protonic acid. SiO2-bound catalysts have less strong acidity, Bronsted acidity and Lewis acidity than the zeolite powder. Also, the strength of strong acid sites of the zeolites is reduced when silica is embedded. Micropore surface area and micropore volume are reduced by about 19% and 18%, respectively, indicating some micropores of ZSM-5 are blocked on binding with silica. SiO2-bound ZSM-5 catalysts have less catalytic activity for butane transformation (cracking and disproportionation) and ethylene oligomerization than ZSM-5 powder. When alumina is used as a binder, both the total acid sites and Lewis acid sites are increased. Micropore surface area and micropore volume of ZSM-5 powder are reduced by 26% and 23%, respectively, indicating some micropores of ZSM-5 are blocked by the alumina binder. Alumina-bound catalysts showed a lower activity for butane transformation and ethylene oligomerization than ZSM-5 powder. Alkaline metals content in the binder is a crucial factor that influences the acidity of a bound catalyst. The metal cations neutralize more selectively Bronsted acid sites than Lewis acid sites. Alkaline metal cations in the binder and micropore blockage cause the bound catalysts to have a lower catalytic activity than the zeolite powder.

Thesis (Ph. D.)--Johns Hopkins University, 1928. / Biography.

<p> A catalytic tubular reactor has been built and interfaced to a minicomputer located at some distance from the actual process equipment. Software has been written to control and monitor the hydrogenolysis of butane within this reactor. The principal aims of this thesis are to describe the process equipment, to detail the structure of the real-time control and monitor software developed for use on a Supernova minicomputer and to demonstrate that the process may indeed be controlled by direct digital control. Finally, in view of the success of the study, a recommendation to explore the applicability of modern control theory is made, particularly, the formulation of an optimal control and changeover policy and the development of multivariable control. </p> / Thesis / Master of Engineering (MEngr)

The following compounds have been prepared and purified and the boiling points, densities, refractive indicies and infrared spectra of each have been determined and recorded: n-butyraldazine, isobutyraldazine, methylethyl ketazine, 1,2-di-n-butylhydrazine, 1,2-diisobutylhydrazine, 1,2-di-sec.-butylhydrazine, 1,1'-azobutane, 1,1'-azoisobutane and 2,2'-azobutane. Vapor pressure curves and freezing points of 1,1'-azobutane, 1,1'-azoisobutane and 2,2'-azobutane have been determined and recorded. The kinetics of thermal decomposition of 1,1'-azobutane, 1,1'-azoisobutane, and 2,2'-azobutane in a flow system using hydrogen and helium as a carrier gases have been investigated. The investigation was carried out for two different concentrations of the azo compounds over a pressure range of 670 to 890 mm. Hg and a temperature range of 260° to 380° C. The decomposition reactions were found to be first order in all cases. The appropriate first order rate expressions have been determined and recorded for the decompositions. The concentrations of the azo compounds were in the range of one to six mole per cent. The first order rate constant for the decomposition of the three azo compounds at a concentration of 1.1 mole per cent in helium are as follows: 1,1'-Azobutane: k = 1.3 x 1017 x e-51,600/RT 1,1'-Azoisobutane: k = 1.6 x 1016 x e-46,200/RT 2,2'-Azobutane: k = 1.8 x 1017 x e-48,200/RT The reaction rate constants, the energies of activation based on a collision theory and the entropies and enthalpies of activation based on the absolute reaction rate theory have been determined and recorded for the three azo compounds. The products of decomposition have been investigated using gas chromatography. The results of these investigations have shown that the decomposition process is complex. Several reactions have been postulated to explain the presence of these decomposition products.

M.S.

The work encompassed by this thesis is partially a reproduction of the results obtained by John A. Marcia in his work on the photo-chemical reactions of branched hydrocarbons. The previous work done on this particular problem was rendered partially valueless because of the loss of the liquid hydrocarbon product when a fractionation column at the Texas Company Laboratory, Beacon, New York, broke during the fractionation run.

Industrial catalysts used in commercial processes for the production of maleic anhydride are mainly Vanadium Phosphorous Oxide (VPO) catalysts. The VPO catalyst used is Vanadyl Pyrophosphate (VO)2P207 made from its precursor Vanadium Phosphorous Hemi-Hydrate VOHP04.O.5H20 in an non-aqueous medium. In order for the VPO catalyst to perform optimally, a metal promoter, Ru, was selected as the doping agent in this study. Four catalysts of different metal doping concentrations (undoped, 0.2%, 0.6% and 1%) were subjected to the oxidation of n-butane. Promoters are added to facilitate the oxidation of n-butane to maleic anhydride. n-Butane gas is now being used in many industrial processes, in fixed bed reactors to convert the gas to maleic anhydride. Catalysts were calcined under high temperatures under a nitrogen atmosphere. It was found that with an increase in reaction temperature, there was an increase in conversion of n-butane to maleic anhydride. Selectivity of the product also showed an increase with an increase in temperature at a Gas Hourly Space Velocity (GHSV) of 1960-2170hr-1. Catalysts were characterized using different techniques such as Electron Dispersive X-Ray Spectroscopy, Inductively Coupled Plasma-Atomic Emission Spectroscopy, Fourier Transform - Infra Red, Average Oxidation State, Brunauer Emmett and Teller (surface area), X-Ray Diffraction and Scanning Electron Microscopy. The 0.6% Ru promoted VPO catalyst showed to be most effective in terms of conversion, selectivity and yield, at a temperature of 450°C as compared to the other catalysts studied. The catalysts degenerated after being subjected to higher temperatures. The selectivity obtained by this catalyst was at 70.2% and the yield obtained was 37%. This study showed that with an increase in Ru up to a certain concentration (0.6%), an increase in selectivity and yield was observed, thereafter, with additional Ru doping, a decrease in selectivity and yield was obtained. / Thesis (M.Sc.)-University of Natal, 2003.

Co promoted and unpromoted vanadium-phosphorous-oxide (VPO) catalysts were synthesized via an organic route. The catalyst precursor was calcined and then conditioned in a reactor, forming the active vanadyl pyrophosphate, (VO)2P2O7, phase. Different promoter loaded catalysts were synthesized and their effect on the yield of maleic anhydride (MA) from n-butane oxidation was examined at different temperatures and gas hourly space velocities (GHSV). The catalysts were tested as a powder. The catalysts were examined in the oxidation of n-butane gas, over air as an oxidant, in a specially designed and constructed continuous flow, fixed-bed catalytic micro-reactor equipped with an on-line gas chromatography (GC) monitoring system. A thermal conductivity detector (TCD) was employed for carbon oxide monitoring and a flame ionization detector (FID) for all other products. The catalysts were characterised by X-ray diffraction (XRD) to determine the phases present in the precursor, calcined and used catalysts. The Brunauer-Emmet-Teller (BET) surface area was calculated for the different promoter loaded catalysts. Fourier transform infrared (FT-IR) spectra, via the KBr pellet method, and attenuated total reflectance (ATR) spectra were recorded to determine the anions present in the bulk and surface of the catalyst respectively. Energy dispersive X-ray (EDX) and inductively couple plasma-atomic emission spectroscopic (ICP-AES) techniques were employed to determine the elemental composition on the surface and in the bulk of the catalyst respectively. Scanning electron microscopic (SEM) images of the catalysts during different stages of their investigation were recorded. The average vanadium oxidation state (AV) in the bulk of the catalyst was determined via a titrimetric method. The catalysts were optimized to a high yield and selectivity of MA. The operating temperature, GHSV and promoter loading on the catalyst were the parameters that were changed during the testing of the catalyst. Different stages of the catalyst's life were characterised via the techniques mentioned above. The catalysts were monitored over a 200-hour period on average, usually taking approximately 24 hours to equilibrate. One such Co promoted catalyst yielded 45 % MA at 275°C and GHSV of 2878 hr-1 on equilibration, with an n-butane conversion of 73 %, whilst all previously reported VPO catalysts produce far lower MA yields at this temperature. / Thesis (M.Sc.)-University of Natal, Durban, 2002.

Zugl.: Karlsruhe, Univ., Diss., 2007 / Hergestellt on demand. - Auch im Internet unter der Adresse http://www.uvka.de/univerlag/volltexte/2008/295/ verfügbar

Zugl.: Karlsruhe, Univ., Diss., 2007