A significant challenge in large scale industrial production of butanol is its low product titer. Butanol needs to be purified to higher than 99% purity in order to be used for fuel applications. The focus of this study is to selectively remove water from butanol-water vapor to achieve fuel grade butanol in a pressure swing adsorption (PSA) system using biosorbents developed from agricultural byproduct canola meal (CM). CM was characterized by Fourier Transform Infrared Spectroscopy (FTIR) that CM contains polar groups such as hydroxyls, carboxyls, and amines in cellulose, hemi-cellulose and protein that have the potential for water adsorption. Physico-chemical characterizations were also done to understand the major composition, elemental make-up, devolatilization characteristics and particle size distribution of the CM used. The results demonstrated that biosorbent based on CM was able to successfully dry lower grade butanol and generate fuel grade butanol of over 99 v/v%. Five operating parameters were studied at two different levels to get the optimum process conditions for butanol drying, including temperature (95 and 111°C); pressure (135 and 201 kPa); feed butanol concentration (55 and 95 v/v %); feed flow rate (1.5 and 3 mL min-1) and particle size of adsorbent (0.425-1.18 mm and 4.7 mm pellets). Orthogonal array design (OAD) tool was used to design experiments and to evaluate the effects of these parameters. The performance of butanol dehydration was evaluated using five indices - water uptake; butanol uptake; water selectivity; butanol recovery; and maximum effluent butanol concentration in the effluent. The results demonstrated that feed butanol concentration, temperature and pressure were found to be the most significant factors overall, affecting most of the indices. The effects of individual operating parameters on each butanol dehydration index were determined and a set of optimum operating conditions were proposed by the range analysis of the orthogonal array design at 111oC, 135 kPa, feed butanol concentration of 55 v/v%, feed butanol-water liquid flowrate of 3 mL/min and biosorbent particle size of 0.43-1.18 mm. The experiments conducted at the above mentioned optimum conditions resulted in water uptake of 0.48 g/g-ads, water selectivity of 5.4, butanol recovery of 90%, and the maximum butanol concentration in the effluent being over 99 v/v% , which are better than that obtained at any other conditions investigated in this work. The Dubinin–Polanyi model based on adsorption potential theory displayed a goodness of fit to the water adsorption isotherm data with a r2 value of 0.95 and average relative error of just 3.5%. The mean free energy determined from the model was 0.02 kJ/mol indicated the adsorption is physical. Thermodynamic parameters were also evaluated which revealed that the water adsorption is exothermic and spontaneous. Water saturated adsorbent was regenerated at 110°C under vacuum and reusability was studied. The contribution of two major components of CM namely cellulose and protein were also examined for their capability to selectively remove water from butanol. The results showed both of them were able to dry water, however cellulose was found to have a higher water uptake and water selectivity than protein, indicating that it plays a major role in drying butanol. In order to compare the performance of CM on drying of butanol with other biomaterials, adsorption experiments were done using corn meal as adsorbent, which is one of the most common starch based biosorbents for ethanol drying. The results demonstrated that canola meal had a higher water uptake and water selectivity than corn meal. Use of CM over corn meal adsorbent is also desirable so as to avoid placing pressure on food consumption. In addition, drying of butanol using other cellulose based biosorbents such as oat hull was also explored. Oat hull demonstrated a potential to adsorb water and dehydrate butanol, which requires further in-depth investigation.

No description available.

With growing concerns over emissions, homogeneous charge compression ignition (HCCI) engines offer a promising solution through reducing NOx and particulate emissions and increasing efficiency. However, this technology is not without its challenges and numerical modeling of these engines can offer some insight into addressing these challenges. This study uses domain decomposition with FORTRAN MPI to subdivide computationally intensive sections of a 10 zone simulation model. Using an Intel i7 quadcore workstation the parallelized model reduced runtimes by half compared to serial computations. From here, two sets of biofuel experimental data were used to improve the validation base of the model. The fuels used were a simulated biomass derived gas (consisting of H2, CH4, CO, CO2, and N2) and a butanol/n-heptane blend. Once calibrated, the model showed good pressure, heat release, and products of incomplete combustion prediction for biogas. NOx emissions were high, however the overall trend was captured. Similarly, once calibrated to the butanol/n-heptane data to account for some of the effects of negative valve overlap (NVO), excellent pressure and heat release predictions were obtained. However, products of incomplete combustion and NOx were low and this was attributed to the inability of the model to properly account for inhomogeneity and all the effects of NVO. Once again though, the overall trend in NOx levels was captured by the model. It was also found that the model does not operate very well near the misfire limit of the engine as it cannot capture the cyclic variability that can occur here. Based on the two new validation cases, it is concluded that once calibrated, the model can be used as a predictive tool for pressure, heat release, and combustion phasing of biofuelled HCCI engines. Furthermore, to improve its predictive capabilities, it is recommended that the model be restructured to incorporate mass transfer between zones, a fixed crevice volume and variable thermal boundary layer, and a CFD solver to improve emissions predictions and reduce reliance on calibration. Finally, changing the zone distribution from ring like zones to lumped stirred reactors is recommended to allow for more realistic modeling of actual experimental HCCI conditions.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1941. / Includes bibliographical references (p. 56-57).

Syngas is a mixture of hydrogen (H2), carbon monoxide (CO) and other species including nitrogen (N2), water (H2O), methane (CH4) and higher hydrocarbons. Syngas is a highly desired product because it is very versatile. It can be used for combustion in turbines or engines, converted to H2 for use in fuel cells, turned into diesel or other high-molecular weight fuels by the Fischer-Tropsch process and used as a chemical feedstock. Syngas can be derived from hydrocarbons in the presence of oxidizer or water as in steam reforming. There are many demonstrated methods to produce syngas with or without water addition including catalytic methods, plasma reforming and combustion. The goal of this study is to add to the understanding of non-catalytic conversion of hydrocarbon fuels to syngas, and this was accomplished through two investigations: the first on fuel conversion potential and the second on the effect of preheat temperature. A primarily experimental investigation of the conversion of jet fuel and butanol to syngas was undertaken to understand the potential of these fuels for conversion. With these new data and previously-published experimental data, a comparison amongst a larger set of fuels for conversion was also conducted. Significant soot formation was observed in experiments with both fuels, but soot formation was so significant in the jet fuel experiments that it limited the range of experimental operating conditions. The comparison amongst fuels indicated that higher conversion rates are observed with smaller molecular weight fuels, generally. However, equilibrium calculations, which are often used to determine trends in fuel conversion, showed the opposite trend. In order to investigate preheat temperature, which is one important aspect of non-catalytic conversion, experiments were undertaken with burner-stabilized flames that are effectively 1-D and steady-state. An extensive set of model calculations were compared to the obtained experimental data and was used to investigate the effect of preheat temperatures that were beyond what was achievable experimentally. Throughout the range of operating conditions that were tested experimentally, the computational model was excellent in its predictions. Experiments where the reactants were preheated showed a significant expansion of the stable operating range of the burner (increasing the equivalence ratio at which the flame blew off). However, increasing preheat temperature beyond what is required for stabilization did not improve syngas yields. / text

With growing concerns over emissions, homogeneous charge compression ignition (HCCI) engines offer a promising solution through reducing NOx and particulate emissions and increasing efficiency. However, this technology is not without its challenges and numerical modeling of these engines can offer some insight into addressing these challenges. This study uses domain decomposition with FORTRAN MPI to subdivide computationally intensive sections of a 10 zone simulation model. Using an Intel i7 quadcore workstation the parallelized model reduced runtimes by half compared to serial computations. From here, two sets of biofuel experimental data were used to improve the validation base of the model. The fuels used were a simulated biomass derived gas (consisting of H2, CH4, CO, CO2, and N2) and a butanol/n-heptane blend. Once calibrated, the model showed good pressure, heat release, and products of incomplete combustion prediction for biogas. NOx emissions were high, however the overall trend was captured. Similarly, once calibrated to the butanol/n-heptane data to account for some of the effects of negative valve overlap (NVO), excellent pressure and heat release predictions were obtained. However, products of incomplete combustion and NOx were low and this was attributed to the inability of the model to properly account for inhomogeneity and all the effects of NVO. Once again though, the overall trend in NOx levels was captured by the model. It was also found that the model does not operate very well near the misfire limit of the engine as it cannot capture the cyclic variability that can occur here. Based on the two new validation cases, it is concluded that once calibrated, the model can be used as a predictive tool for pressure, heat release, and combustion phasing of biofuelled HCCI engines. Furthermore, to improve its predictive capabilities, it is recommended that the model be restructured to incorporate mass transfer between zones, a fixed crevice volume and variable thermal boundary layer, and a CFD solver to improve emissions predictions and reduce reliance on calibration. Finally, changing the zone distribution from ring like zones to lumped stirred reactors is recommended to allow for more realistic modeling of actual experimental HCCI conditions.

Universiẗat, Diss.--Paderborn, 1994.

Stuttgart, Univ., Diss., 2004.

Submitted by Livia Mello (liviacmello@yahoo.com.br) on 2016-10-03T14:35:17Z No. of bitstreams: 1 DissAB.pdf: 4200457 bytes, checksum: 7789cd2b6d970ee78f965e8893a53638 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-20T19:26:33Z (GMT) No. of bitstreams: 1 DissAB.pdf: 4200457 bytes, checksum: 7789cd2b6d970ee78f965e8893a53638 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-20T19:26:40Z (GMT) No. of bitstreams: 1 DissAB.pdf: 4200457 bytes, checksum: 7789cd2b6d970ee78f965e8893a53638 (MD5) / Made available in DSpace on 2016-10-20T19:26:46Z (GMT). No. of bitstreams: 1 DissAB.pdf: 4200457 bytes, checksum: 7789cd2b6d970ee78f965e8893a53638 (MD5) Previous issue date: 2016-04-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / The effect of metal composition (Ni,Co) and the reactants composition (H2:H2O:Butanol) in the catalytic properties were studied for the Ni,Co/MgAl2O4 catalysts in the reaction of steam reforming of butanol (SRB) The catalysts have been prepared by wet impregnation with alcoholic solution of the Co and Ni nitrates on the support of the spinel MgAl 2O4 kind, prepared by the sol-gel method. The catalysts have been characterized by N2 physisorption, X-ray diffraction (XRD), temperatura programmed reduction (TPR), thermogravimetric analysis (TGA) and X-ray absorption near edge structure (H2-XANES). The catalytic tests had been realized in the 150-650°C temperature range, making testes with He flow and others with H2 flow (strongly reducing atmosphere), evaluating conversion, products distribution and H2 selectivity. The XRD reesults confirmed the formation of MgAl2O4 spinel structure and revealed some traces of NiO in the catalyst with 8% of Ni in mass. The TPR helped in the identification of the reducing temperatures of the catalysts. TPD revealed that the main route of butanol’s decomposition in the catalyst surface is the dehydration, producing butylene and etylene. The catalytic tests have indicated another main route, the oxidative dehydrogenation, forming butyraldehyde as the first relevant product of the reaction. The main difference between TPD and catalytic tests is that during the reaction, the presence of water keept the catalyst oxidized in low temperatures. By the XANES evaluation of the results, along with the comparison between TPD and catalytic tests, is suggested that butanol have the tendency to form butyraldehyde when there are more oxide concentration. The TGA revelead that wasn ́t formed significant quantity of the coke in the catalyst surface, probably due to the steam/carbon rate utilized in the catalytic tests. The catalysts had obtained equivalent performance related to H2 selectivty, having some small diferences related to the intermediate products of the reaction, and in the temperature which they were formed during the catalytc tests, as well. / O efeito da composição de metal (Ni,Co) e a composição dos reagentes (H2:H2O: Butanol) nas propriedades catalíticas foram estudados para os catalisadores Ni,Co/MgAl2O4 na reação de Reforma a Vapor do Butanol (RVB). Os catalisadores foram preparados por impregnação úmida com solução alcoólica dos nitratos de Co e Ni sobre o suporte do tipo espinélio MgAl2 O4, preparado pelo método sol-gel. Os catalisadores foram caracterizados por fisiossorção de N2 , difração de raios X (XRD), redução à temperatura programada (TPR), análise termogravimétrica (TGA) e espectroscopia de absorção de raios X próximo da borda (H2-XANES). Os testes catalíticos foram realizados na faixa de temperatura de 150 a 650°C, fazendo testes com fluxo de He e outros com fluxo de H 2 (superfície fortemente redutora), avaliando a conversão, distribuição de produtos e seletividade para H2. Os resultados de XRD confirmaram a formação da estrutura de espinélio MgAl2O4 e revelaram alguns traços de NiO no catalisador de 8% em massa de Ni. O TPR, por sua vez, ajudou na identificação das temperaturas de redução dos catalisadores. O TPD revelou que o principal caminho de decomposição do butanol na superfície do catalisador é a desidratação, produzindo butileno e etileno. Os testes catalíticos indicaram outro caminho principal, a desidrogenação oxidativa, formando butiraldeído como primeiro produto relevante da reação. A principal diferença entre o TPD e os testes catalíticos é que durante a reação, a presença de água mantém o catalisador oxidado em temperaturas mais baixas. Pela avaliação dos resultados de XANES, juntamente com a comparação do TPD e dos testes catalíticos sugere-se que o butanol tende a formar butiraldeído quando há maior concentração de óxidos. A TGA revelou que não foi formada quantidade significativa de coque na superfície do catalisador, muito devido à relação água/carbono utilizada nos testes catalíticos. Os catalisadores obtiveram desempenhos equivalentes em relação à seletividade à H2, possuindo diferenças em relação a alguns produtos intermediários da reação, bem como na temperatura em que eles foram formados no decorrer dos testes catalíticos.

In this thesis, a theoretical description of mass transport through membranes used in pervaporation separation processes has been investigated for both dense polymeric membranes and mixed matrix membranes (MMMs). Regarding the dense polymeric membranes, the Maxwell-Stefan model was extended to consider the effect of the operating temperature and membrane swelling on the mass transport of species within the membrane. The model was applied semi-empirically to predict the membrane properties and separation performance of a commercial Polydimethylsiloxane (PDMS) membrane used in the pervaporation separation of butanol from binary aqueous solutions. It was observed that the extended Maxwell-Stefan model has an average error of 10.5 % for the prediction of partial permeate fluxes of species compared to roughly 22% for the average prediction error of the Maxwell-Stefan model. Moreover, the parameters of the model were used to estimate the sorption properties and diffusion coefficients of components through the PDMS membrane at different butanol feed concentrations and operating temperatures. The estimated values of the sorption properties were observed to be in agreement with the literature experimental data for transport properties of butanol and water in silicone membranes while an exact comparison for the diffusion coefficient was not possible due to large fluctuations in literature values. With respect to the MMMs, a new model was developed by combining a one-directional transport Resistance-Based (RB) model with the Finite Difference (FD) method to derive an analytical model for the prediction of three-directional (3D) effective permeability of species within ideal mixed matrix membranes. The main novelty of the proposed model is to avoid the long convergence time of the FD method while the three-directional (3D) mass transport is still considered for the simulation. The model was validated using experimental pervaporation data for the separation of butanol from aqueous solutions using Polydimethylsiloxane (PDMS)/activated carbon nanoparticles membranes and using data from the literature for gas separation application with MMMs. Accurate predictions were obtained with high coefficient of regression (R2) between the calculated and experimental values for both applications.