Carlos O. Castillo-Araiza

Cadmium(II), Lead(II), and Copper(II) Biosorption on Baker’s Yeast (Saccharomyces cerevesiae)

AbstractThe biosorption properties of ethylenediaminetetraacetate (EDTA)-treated biomass of baker’s yeast (Saccharomyces cerevisiae) are studied for the removal of Cadmium(Cd), Lead(Pb), and Copper(Cu) from artificially prepared industrial wastewater. The metal ions are chosen for biosorption studies with regard to their availability in industry and potential pollution impact. The optimum biosorption capacity of these metal ions on the biomass is obtained at pH 5. It is observed that the sorption capacity of EDTA-treated biomass increases when the initial concentration of the metal ions is increased. Both Langmuir and Freundlich isotherm models are used to fit experimental biosorption equilibrium data. The maximum biosorption capacity as determined via the Langmuir isotherm is 32.26, 200.0, and 17.24  mg/g for Cd(II), Pb(II), and Cu(II) ions, respectively. The kinetics of biosorption is studied using both pseudo first order and pseudo second order models. Based on a linear regression correlation coefficie...

Hydrodynamic Models for Packed Beds with Low Tube-to-Particle Diameter Ratio

In the last decade it has been a special interest to incorporate the hydrodynamics in packed bed reactor models. This seems to be important in the case of highly exothermic partial oxidation reactions normally performed in packed beds with low tube/particle diameter ratio (dt/dp< 5) because of the large void distributions in the radial and axial directions, which have a direct impact on the magnitude of radial, angular and axial profiles of the velocity field, and consequently on both, the temperature and concentration profiles in the catalytic reactor. A successful reactor model needs an adequate hydrodynamic description of the packed bed, and for this reason several models additionally incorporate empirical expressions to describe radial voidage profiles, and use viscous (Darcy) and inertial (Forchheimer) terms to account for gas-solid interactions, via Erguns pressure drop equation. In several cases an effective viscosity parameter has also been used with the Brinkmans viscous term. The use of these various approaches introduce some uncertainty in the predicted results, as to which extent the use of a particular radial voidage expression, or the use of an effective viscosity parameter, yield reliable predictions of measured velocity profiles.In this work the predictions of radial velocity profiles in a packed bed with low tube to particle diameter ratio from six hydrodynamic models, derived from a general one, are compared. The calculations show that the use of an effective viscosity parameter to predict experimental data can be avoided, if the magnitude of the two parameters in Erguns equation, related to viscous and inertial energy losses, are re-estimated from velocity measurements, for this particular packed bed. The predictions using both approaches adequately fit the experimental data, although the results are analyzed and discussed.

Elucidating kinetic, adsorption and partitioning phenomena from a single well tracer method: Laboratory and bench scale studies

Abstract This study is aimed at giving some insights on kinetics, adsorption and partitioning of ethyl acetate during a single well tracer test. Synthetic formation water, an specific crude oil and a silicate-dolomite rock were used during experiments performed in laboratory and bench scale systems. Independent sets of experiments were designed to calculate the partition coefficient of ethyl acetate between the formation water and the oil, to develop a kinetic model for the hydrolysis of ethyl acetate, and to derive isotherm and kinetic models for the adsorption of ethyl acetate on the rock. These tracer experiments were evaluated at a concentration range (100–300 mmol.L−1) similar to that supposed to be used in the single well tracer method. All parameters determined from these experiments were validated describing observations from stirred batch and column systems, in which kinetic, adsorption and partitioning phenomena occurred at the same time. Pseudo-heterogeneous models, accounting for three phases namely the formation water, the rock and the oil, were applied to elucidate the interaction of the different mechanisms involved in these set-ups. Main results are summarized as follows: (i) partition coefficients (KEA) were apparent varying from ca. 5–8 because of thermodynamic constraints; (ii) kinetic models for the hydrolysis of ethyl acetate were developed under acid and basic conditions since at neutral ones there were negligible conversions; (iii) the combined Langmuir-Freundlich isotherm and the Langmuir kinetics were the most suitable models describing equilibrium and adsorption rate observations, respectively; (iv) the studied rock adsorbed significant amounts of ethyl acetate, leading to a maximum adsorption capacity (qEAm) of ca. 7.0 mmol.g−1 at studied operating conditions; (v) the adsorption kinetic model rather than the simplified isotherm model seems necessary to describe this phenomenon from the single well test evaluating ethyl acetate as the tracer; and (vi) partition, hydrolysis and adsorption parameters evaluated from independent experiments allowed us to describe observations from both stirred batch and column systems. These results disclose the importance of accounting for partition, hydrolysis and adsorption mechanisms in a single well method using ethyl acetate as the tracer.

Hydrodesulfurization of Dibenzothiophene in a Micro Trickle Bed Catalytic Reactor under operating conditions from Reactive Distillation

Abstract The hydrodesulfurization (HDS) of dibenzothiophene (DBT) is investigated over a commercial NiMoP/γ-Al2O3 catalyst in a micro trickled bed reactor (Micro-TBR) at operating conditions of a reactive distillation (RD) column. An analysis with and without reaction is carried out to have a first understanding on the complex interaction between kinetics and transport phenomena. A set of well-accepted criteria is evaluated to elucidate the presence of heat and mass transport limitations. Residence time distribution (RTD) experiments are performed to evaluate axial dispersion through the estimation of axial dispersion coefficient (Daxial,L) from a convection-dispersion model. Experiments with reaction are carried out using hydrogen and DBT as feedstock at reaction temperatures from 533 to 599 K, pressures from 1.5 to 2.5 MPa and inlet molar flow of DBT from 4 to 12×10–8 mol.s–1. A pseudo heterogeneous model accounting for mass transport limitations is used to describe experiments under reaction conditions. The main findings can be summarized as follows: most of RD operating conditions lead to the presence of interfacial mass transport limitations at both interfaces L-S and G-L; convection-dispersion model is able to describe satisfactorily RTD observations, suggesting that axial dispersion phenomena are negligible; conversion of DBT ranges from ca. 22 to 90% having a selectivity to by-product molecules from 30 to 80%, respectively; and the pseudo heterogeneous reaction model describes observations adequately obtaining activation energies ranging from 49 to 62 kJ mol–1 at pressures from 1.5 to 2.5 MPa, respectively. Estimated activation energies are comparatively lower than the activation energies reported in literature for the conventional HDS process, i.e. 40–160 kJ.mol–1, thereby suggesting an apparent catalytic energy savings by using RD technology.

One-Pot Isomerization of n-Alkanes by Super Acidic Solids: Sulfated Aluminum-Zirconium Binary Oxides

Abstract Super acidic nanostructured sulfated aluminum-zirconium binary oxides in mole ratios of Zr4+: Al3+ as 2:1 (SAZ-1), 1:1 (SAZ-2), 1:2(SAZ-3) and the reference catalyst super acidic sulfated zirconia (SZ) were synthesized by a precipitation method. Firstly, the catalytic performance of these four catalysts was evaluated during the isomerization of n-hexane to 2-methyl pentane and 3-methyl pentane, n-heptane and n-octane to their corresponding branched chain isomers at low temperature and pressure conditions (40°C and 1 atm). SAZ-1 performed the highest active and selective isomerization of n-hexane, n-heptane, and n-octane into their corresponding branched chain isomers. The catalytic activity of the reference catalyst SZ was the lowest among the four synthesized catalysts. TEM analysis applied to SAZ-1 and SZ indicated the presence of particle-bulks having average size of 20 nm; moreover, these materials presented an amorphous nature, having no particular surface morphology. XRD confirmed the amorphous structure of SAZ-1 and SZ as well as indicated their internal phase structure. FTIR generated ideas about different linkages and bond connectivities between atoms and groups in SAZ-1 and SZ. Ammonia-TPD of these two materials confirmed the higher super acidic nature of SAZ-1 and lower super acidic nature of SZ. Catalyst evaluation and characterization allowed to propose a reaction mechanism, elucidating a possible role of Brønsted and Lewis acid sites on the studied reaction-catalyst, being the former active sites the main factor leading to isomerization reaction. AFM and SEM pictures indicated the nature of the surface of the catalysts. Nevertheless, SEM analysis before and after the reaction displayed that catalyst morphology was modified and could influence the activity of the catalyst. The use of SAZ-1 is cost saving as well as energy saving.

Study of the Agglomeration Mechanism of a Natural Organic Solid in a Bench-Scale Wet Fluidized Bed Using Statistical Analysis and Discretized Population Balance

In the present work the agglomeration of a natural organic solid in a top-spray fluidized bed at bench scale was studied by means of statistical analysis and modeling using a discretized population balance. These engineering approaches were coupled to elucidate the influence of elutriated fines recirculation and its interaction with bed temperature and atomizing binder time on agglomeration mechanisms of solids presenting initial particle diameter polydispersity. First, a 23 factorial design was considered, accounting for the factors of atomizing binder time and bed temperature with and without consideration of the recirculation of elutriated fines into the fluidized chamber. Second, the agglomerate observations were analyzed by a variance analysis, with a significance level of 5%, using the mean particle diameter as response variable. Finally, the observations were predicted through a discretized population balance accounting for nucleation, agglomeration, and growth kinetics. The results indicated that bed temperature and atomizing binder time, together with the interaction between bed temperature and the recirculation of elutriated fines, were factors affecting agglomeration mechanisms. Nucleation and aggregation mechanisms were dominant when the lowest bed temperature and the longest atomizing binder time under fines recirculation conditions were used.

Kinetic and reactor performance of a Ni-based catalyst during the production of ethene

ABSTRACT Steam cracking of diverse hydrocarbon sources is nowadays the main technology used to produce ethene worldwide, however, it presents energetic and environmental limitations related to the large consumption of energy and production of carbon oxides. To overcome this, industry and academy have aimed their research at developing a new technology based on the oxidative dehydrogenation (ODH) of ethane. Main challenges for its industrial implementation are yet catalyst and industrial reactor design. In this sense, Ni based catalysts have been promising materials for the production of ethene out of ethane at laboratory scale, however there is a scarce amount of researching on engineering aspects related to the evaluation of their performance at industrial scale. This work is aimed at giving insights on the performance of a Ni-loaded Y zeolite catalyst (Ni/KY) during the ethene production via ODH of ethane in an industrial-scale wall-cooled fixed bed catalytic reactor with a low dt/dp. To achieve this, an industrial reactor model that couples reaction kinetics to heat and mass transport phenomena is developed following reactor engineering fundamentals. To assess the kinetics of the ODH of ethane over the aforementioned catalyst, a detailed kinetic model is developed using published experiments [J. Catal. 265 (2009) 54–62]. Then, this kinetics is coupled to the industrial-scale reactor model, a 2D heterogeneous model accounting for heat and mass transport. The kinetic model following a Langmuir–Hinshelwood–Hougen–Watson mechanism allows an accurate description of laboratory data. Activation energy, related to the formation of ethene, and enthalpy adsorption of ethene indicate that the production ethene is favored at larger reaction temperatures, however, once it is produced, this olefin is more strongly adsorbed on the catalyst surface than the other byproducts. However, from the parametric sensitivity study applied to the industrial reactor, a larger coolant temperature brings out a significant but positive effect on the yield of ethene whereas a lower concentration of ethane in the feedstock favors the oxydehydrogenation reaction rather than total oxidation reactions. To this end, the proposed industrial reactor technology, along with the Ni/KY material, overcomes the hot spot formation and enables operations at larger temperatures, hence, favoring the production of ethene rather than carbon oxides.

Preface to the Special Issue Dedicated to the International Energy Conference, IEC 2017: Energy and its Development in the Twenty-First Century: A globalized vision

This Special Issue of the International Journal of Chemical Reactor Engineering (IJCRE) is comprised of full manuscripts from many of the presentations from the International Energy Conference (IEC-2017). This international convention was held from September 4 to 8, 2017 at the Centro de Educación Continua Ing. Eugenio Méndez Docurro, Instituto Politécnico Nacional in Mexico City, Mexico. This conference center was built between 1588 and 1598. Given its historical significance, it was chosen as a fitting venue for this notable international conference.

Special Issue in Honor of J. Alberto Ochoa-Tapia

Professor J. Alberto Ochoa-Tapia is a world renowned Mexican Chemical Engineer. Alberto obtained his PhD doctorate degree from the University of California at Davis in 1988. At the present time, Alberto is a Full Professor at Universidad Autónoma Metropolitana (UAM) in Mexico City (1994-to date). His record of academic positions includes being Full Professor at the Universidad Autónoma de Puebla, Mexico (1980–1983) and at the Instituto Tecnológico de Celaya, Mexico (1989–1994). In addition, in recent years, Alberto has had Visiting Professorship appointments at the University of Paris VI and at the École Centrale de Paris. Furthermore, Alberto was the Director of the Graduate Program of Chemical Engineering as well as the head of the Department of Process Engineering and Hydraulics at UAM during the 2012–2014 period. Alberto was also the 1993–1995 President of the AMIDIQ (Mexican Academy of Teaching and Research in Chemical Engineering), and in 2001 a founding member of the Revista Mexicana de Ingeniería Química. More recently, Alberto was the founder and first President of the Mexican chapter of Interpore, the International Society for Porous Media. Alberto has made significant advances in the study of transport phenomena in systems that involve disparities of scales, such as porous media systems. Over the nearly four decades of his scientific career, the diverse research interests of Alberto have included: (a) The development of models for momentum, heat and mass transport in the bulk of porous media and multiphase systems, (b) The establishment of boundary conditions between a porous medium and a homogeneous fluid phase, (c) The development of both analytical and numerical methodologies for solving, linear and nonlinear, boundary-value problems, (d) The study of transport in liquid membranes and double emulsion systems. As well, Alberto’s interests in modeling have considered the dynamics of heterogeneous chemical reactors and of catalyst poisoning due to coke formation. Alberto is the author of more than 70 scientific papers and the number of citations of his papers is greater than 1500. He has published more than 40 proceedings in national and international conferences. Alberto’s research accomplishments have been acknowledged with keynote speaker invitations to many national and international forums. He was the advisor to 28 Master and 11 PhD students who graduated with successful

Degradation and Mineralization of a Cationic Dye by a Sequential Photo-Sono Catalytic Process

Abstract The photocatalysis, sonocatalysis and their combination operated sequentially have been studied to treat the decolorization and mineralization of a cationic dye, Rhodamine B, using heterogeneous TiO2 catalyst. Effects of various operating parameters such as catalyst loading, H2O2 addition, and pH on photocatalytic and sonocatalytic processes were investigated. For both photocatalysis and sonocatalysis optimum catalyst and hydrogen peroxide concentrations were observed, while the dye degradation rates were favored at acidic conditions. Photocatalysis resulted in higher color degradation efficiencies compared with sonocatalysis. Coupled photosonocatalytic process showed better efficiencies for color degradation than the achieved by individual photocatalysis and sonocatalysis operating separately, implying possible synergy; however, no synergetic effect was observed for dye mineralization. Apparently the sequential photosonocatalytic operation process was more effective in inducing color degradation than mineralization.