Gulsen Dogu

Chemical reactor technology for environmentally safe reactors and products

Preface H.I. de Lasa. I: Fuels of the Future and Changing Fuel Needs. How should Environmentally Benign Gasolines be Formulated? A. Ravella. Oxygenates as Gasoline Blending Components G.L. Harting, H. Shannon. Engineering of Fluidized Catalytic Crackers D. King. Scientific Aspects of Novel Catalysts for FCC A.W. Peters, W-C Cheng, T.G. Roberie. Novel Techniques for FCC Catalyst Selection and Kinetic Modelling H.I. de Lasa, D.W. Kraemer. Mixing Patterns in a Novel Riser Simulator A. Pekediz, D.W. Kramer, J. Chabot, H.I. de Lasa. Chemical Aspects of Clean Fuels Production P.H. Schipper, A.V. Sapre, Q.N. Le. II: Alternative Sources. Evaluation of Direct Methane Conversion Processes J.C.W. Kuo. Engineering Aspects of the Conversion of Natural Gas into Middle Distillates M.M.G. Senden, S.T. Sie, M.F.M. Post, J. Ansorge. Steam Reforming Opportunities and Limits of the Technology J. Rostrup-Nielsen, I. Dybkjaer, L.J. Christiansen. Oxidative Coupling of Methane for the Utilization of Natural Gas M. Baerns. Dysprosium Oxide for Oxidative Coupling of Methane O. Altin, I. Onal, T. Dogammau, J.B. Butt. Ultrapyrolysis of Heavy Oils: Reaction Kinetics and Reactor Technology F. Berruti, L.A. Behie. Bubble Column Reactors: Some Recent Developments M.P. Dudukovic, N. Devanathan. Strategies for Low Emissions from Circulating Fluidized Bed Boilers F. Berruti, R. Wong. Kinetic Modeling of Complex Processes. Thermal Cracking and Catalytic Hydrocracking G.F. Froment. Engineering of Hydrotreating Processes P. Trambouze. III: Emission Control, Chemical Reactor Safety and Engineering. Thermal Sensitivity and Runaway in Chemical Reacting Systems G. Cao, M.Morbidelli, A. Varma. Kinetics of Capture of Sulfur Dioxide and Applications to Flue Gas Desulfurization G. Dogu, T. Dogu. Removal of SO2 with Lime Slurry in a Spray Dryer G. Dogu, G. Olmez, T. Dogu. Engineering Aspects of Recirculating Fluidised Bed Combustion C. Brereton, J.R. Grace, C.J. Lim, J. Zhu. Application of a Monte Carlo Method to the Solid Flow Pattern Visualization in CFB B.P.A. Grandjean, J. Chaouki. Modelling Catalytic Monoliths for Automobile Emission Control J.P. Leclerc, D. Schweich. Photocatalytic Processes for Destruction of Organic Water Contaminants E. Pelizzetti, C. Minero, E. Pramauro. Heterogeneous Photocatalytic Degradation of the Cationic Surfactants Cetyldimethylbenzylammonium Chloride and Cetylpyridinium Chloride I. Poulios, A. Avranas. Progress in the Development of Chlorofluorcarbon (CFC) Alternatives J.J. Lerou, L.E. Manzer. Index.

Rate parameters from dynamic experiments with single catalyst pellets

Abstract Equations have been derived relating the rate and equilibrium parameters for adsorption and reaction on a single catalyst pellet to measurable properties of pulse-response experiments. In particular, it is shown that intraparticle diffusivities, adsorption equilibrium constants, and adsorption rate constants can be evaluated from the moments of the response peak from one end face of a catalyst pellet when a pulse of diffusing component is passed over the other end face. The method is illustrated with experimental data for helium (in nitrogen) and cyclopropane (in helium) pulses diffusing through alumina pellets at 35–90°C and atmospheric pressure. The results suggest that this dynamic procedure offers a rapid, simple method for establishing the rate and equilibrium parameters for adsorbing systems, provided all processes are linear. An advantage is that the intraparticle diffusivity can be obtained from the first moment of the response peaks, without recourse to the less accurate, second moment. Extension of the method to first-order reaction systems is discussed. A disadvantage is that the results may not be of high accuracy when many parameters are to be evaluated from one set of data; i.e. from one set of experimental conditions.

Etherification rates of 2‐methyl‐2‐butene and 2‐methyl‐1‐butene with ethanol for environmentally clean gasoline production

Etherification of C5 reactive olefins available in light fluidized catalytic cracking (FCC) gasoline is an attractive way to decrease the olefins and to increase the octane number. The reactivities of 2-methyl-1-butene (2M1B) and 2-methyl-2-butene (2M2B) in the etherification reaction with ethanol catalysed by a strongly acidic macroreticular resin catalyst were investigated in a temperature range of 333–360 K using a liquid phase differential flow reactor. In the presence of excess alcohol, the apparent reaction orders of etherification reactions of isoamylenes were found to be 0.93 and 0.69 with respect to 2M1B and 2M2B concentrations, respectively. 2M1B was shown to be more reactive than 2M2B and its activation energy is also lower in the etherification reaction. It was also shown that diffusion resistances, especially in the macropores of the catalyst, may play an important role on the observed rates. © 1999 Society of Chemical Industry

Conversion of Biodiesel By-Product Glycerol to Fuel Ethers over Different Solid Acid Catalysts

In this study, the etherification reaction of glycerol (G) with tert-butyl alcohol (TBA) was investigated for the production of high quality transportation fuel additives. The reaction was carried out in liquid phase, in a continuous flow reactor in the presence of various solid acid catalysts. Activities of acidic resin catalysts, such as Amberlyst-15 (A-15), Amberlyst-16 (A-16) and Amberlyst-35 (A-35), Nafion-SAC-13 and ?-alumina were compared. Significant increase in conversion was observed with an increase in temperature. Amberlyst 15 showed the highest activity at about 110°C, giving glycerol conversion values of about 0.5 at a space time of 18 g cm-3 s. However, A-16 gave higher di-ether selectivity values. Nafion-SAC-13 showed activity at higher temperatures, while the activity of ?-alumina was very low, even at 400°C.

Breakthrough Analysis OF H 2 S removal on CU-V-MO, CU-V, and CU-MO mixed oxides

Kinetic studies carried out for the sorption of H 2 S in the presence and absence of hydrogen on Cu-V-Mo, Cu-V, and Cu-Mo mixed oxides gave detailed information about the reaction sequences. Formation of SO 2 even in the presence of hydrogen at the initial stages of the sorption process showed the partial reduction of the metal oxides prior to the sulfidation step. A sorption experiment carried out with Cu-Mo mixed oxide gave incomplete sulfidation of molybdenum, whereas with Cu-V mixed oxide complete sulfidation was obtained. Predictions of the breakthrough curves by the deactivation model showed good agreement with the experimental results.

Diffusion Resistances and Contribution of Surface Diffusion in TAME and TAEE Production Using Amberlyst-15

Effective diffusivities and adsorption equilibrium constants of methanol, ethanol and 2-methyl-2-butene (2M2B), in Amberlyst 15, were evaluated from batch adsorption experiments. Moment expressions derived for different models involving diffusion resistances in the macropores and within the gel-like micrograins were used for the evaluation of effective diffusion coefficients. Contribution of surface diffusion to diffusion flux within the macropores was found to be quite significant. Also, it was found that diffusion resistance in liquid filled macropores was much more significant than diffusion resistance within the gel-like micrograins of Amberlyst 15., for methanol, ethanol and 2M2B.

Kinetics of trona sulfur dioxide reaction

Abstract One of the most efficient methods of desulfurization of flue gases involves the reaction of SO 2 with activated soda in a dry system. In this work, reactivities of activated soda produced from trona by direct calcination and by spray drying of trona solution were compared and a reaction mechanism was proposed. Due to the textural variations of the solid during the reaction and due to the increased significance of adsorption of SO 2 , at low temperatures, a two step reaction behavior was observed. Predictions from the deactivation model gave satisfactory agreement with the experimental data.

Kinetics of H2S Sorption on Manganese Oxide and Mn-Fe-Cu Mixed Oxide Prepared by the Complexation Technique

Hydrogen sulfide sorption activities of manganese oxide and Mn-Fe-Cu mixed oxide sorbents were examined in a fixed bed reactor. Sulfur retention capacity of Mn-O sorbent was found to be quite high at 600 °C both in the absence and presence of hydrogen gas (0.17 and 0.14 g S/g sorbent, respectively). This sorbent has a high porosity and a relatively high surface area. Best regeneration temperature of this sorbent was found as 700 °C, with a gas stream containing 6% oxygen in nitrogen. Mn-Fe-Cu mixed oxide sorbent had a lower sulfur retention capacity (0.07 g S/g sorbent). However, both of these sorbents gave quite high initial sorption rate constants, resulting very sharp breakthrough curves. Deactivation model was shown to give good agreement with the experimental H2S breakthrough curves.

Combustion of a high ash and sulfur containing lignite in a pilot circulating fluidized bed combustor and its pollution characteristics

Abstract In this study a 50 kW circulating fluidized bed combustor (low velocity regime CBF combustor) was constructed for the combustion of high ash containing lignites. Beypazarý lignite which contains 45% ash and 3.72% sulfur was mixed with limestone and was burnt in this combustor. Emission characteristics were investigated at different Ca/S mole ratios. It was shown that SO 2 removal efficiencies reached values of 98%. At an average bed temperature of 850°C NO x emission levels were found to be around 300 ppm however CO emissions were around 1466 ppm. Temperature variation along the combustor (of 1.8 m in height) was found to be about 140 and 90°C for two different feed points located at 0.17 and 0.52 m above the distributor and two different feedback points located at 0.37 and 0.17 m above the distributor, respectively.

Kinetics of Capture of Sulfur Dioxide and Applications to Flue Gas Desulfurization

Among all the processes for the desulfiirization of flue gases, the use of carbonates of calcium and sodium is the simplest and the most direct method. The conversion of calcium oxide to calcium sulfate is limited by the plugging of pores with the solid product during reaction. Pore diffusion limitation becomes significant at the initial stages of the reaction unless the particle size is in the order of magnitude of a few microns. On the other hand, diffusion of SO2 through the product layer becomes the most important resistence at later stages of the reaction. Activated soda shows a much higher activity and reacts with SO2 at much lower temperatures. In this manuscript, the significance of structural variations on the reaction and diffusion parameters, the models proposed in the literature, and the experimental techniques used are reviewed and illustrated. It is shown that detailed information can be obtained about desulfiirization reactions using the single pellet dynamic technique. Comparison of calcium and sodium based desulfiirization processes has indicated that activated soda is an attractive alternative to limestone if natural soda is available.