Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) - Volume 11, Issue 2, 2018

Renewable aviation fuel has been identified as the most promissory alternative for the sustainable development of the aviation sector. This renewable fuel can be obtained from triglyceride, lignocellulosic biomass, sugar and starchy feedstock through different processing pathways; however, the hydroprocessing of triglyceride feedstock is the most advanced technology. The modeling and simulation of the hydrotreating processes is a key step to improve it from an energetic point of view; this can be realized through the application of strategies such as energy integration or process intensification. Nevertheless, the reliability of the obtained results depends strongly on reactive and phase equilibrium calculations. In particular, in the hydrotreating process, the conversion of triglyceride feedstock intro hydrocarbons is the key step; and it has been of recent interest in research areas. Therefore, in this work, a review of the kinetic models and global conversions reported for biojet fuel production through hydrotreating process of renewable triglyceride feedstock is presented.

Objective: Third generation biorefineries based on microalgae biomass seem to be a great potential to supply future fuel consumption. However, technological challenges must be faced; such as microalgae harvesting, which is one of the most important bottlenecks. Several technics have been proposed to harvest microalgae such as centrifugation, flotation, precipitation, among others. However, some of them have economical, technical or environmental limitations. In this work, electroflocculation is examined to harvest microalgae using wastewater as growth media. Methods: The best conditions for current intensity, potential, electrodes material, electrolyte and resident time were determined by cyclic voltamperometry, for batch and continuous flow regimens. Results: Through the results of the analysis, the anodic and cathodic reactions were determined and the electroflocculation process performance has been explained. It was observed that oxygen release from the anode contributes significantly to microalgae separation process. Conclusion: Based on these results, it can be established that electroflocculation has a great potential, from a technical and economical point of view, to harvest microalgae.

Background: The production of 2G bio-butanol has been mostly analysed from an experimental approach, while the development of mathematical models has been focused on the evaluation of global process performance and coupling different unit operations. However, modelling and simulation have not been explored to investigate design configurations, which enhance butanol production by additives feeding or biomass confinement. Methods: The methodology included the dynamic mathematical models collection and their implementation in two process configurations which included the pretreatment, enzymatic hydrolysis and butanol production. The evaluation of different acetate and butyrate feeding ratios was investigated within the additives model validity range. Additionally, the effect of biomass recycle was studied. Results: Three scenarios were investigated, the so called ABE: C-C, ABE: C_RECY-C and biomass confinement in ABE: C_RECY-C. Dynamic simulations were performed using stepwise disturbances in the inlet streams of sodium butyrate and sodium acetate. Stationary performance indexes were analysed for each simulation scenario. Continuous hydrolysis and fermentation (ABE: C-C) showed better performance than ABE:C_RECY-C, but relative butanol enhancement in the second configuration was higher and then it was further investigated. The best scenario was obtained using ABE:C_RECY-C and biomass confinement which resulted in a substantial butanol enhancement. Conclusion: The results showed that it was possible to increase the butanol production by adding the proper ratio of acetate and butyrate to the fermentation for each configuration. Compared with the case where none of the additives were fed, both configurations resulted in 44.7% and 58.8% higher concentration of butanol. Additionally, the continuous biomass recirculation to the ABE:C_RECY-C process plus additives resulted in 477% increase in butanol concentration and 97% reduction in the unconsumed substrate.

Background: Cu2ZnFeS3 (CZIS) thin films were grown as a non-toxic material for use in photovoltaic cells as an n-type semiconductor. This material could work in synergy with p-type materials already existing in the market such as CdTe and Cu(In, Ga)Se2 (CIGS). Thin films of CZIS were grown as a quaternary Cu2ZnFeS3 material by the co-evaporation technique under high vacuum from binary sulfides such as iron sulfide (FeS2), copper sulfide (CuS) and zinc sulfide (ZnS), each one individually optimized and characterized. Methods: In this work, the results were performed using different variants such as thermal annealing step in two different atmospheres such as under vacuum, and vacuum-sulfur and also at different temperature (500-600ºC) in order to obtain quaternary materials. The structural, optical, morphological, compositional, and electrical properties of the samples were characterized using X-ray diffraction, UV-Vis spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and Hall effect measurements. XPS results indicate that the samples are slightly rich in Zn and poor in Cu. Conclusion: The evidence of surface oxidation has also been noted. Nevertheless, the depth profile did not show a significant change in the signal or in the composition in the composition. From the UV-Vis analyzes, we obtained optical band gap values with 2.22 < Eg < 2.76 eV. The carrier concentrations were found to be in the range of 3.3 x1020 to 4.6x1021 cm-3, the mobility value was around 4.45-0.22 cm2 V-1s-1, and the resistivity values were determined in the range of 1.68x10-3 to 1.89x10-2 Ω-cm.

From present day's perspective, it has been widely acknowledged that our industrialized modern world requires new ways to solve the global demand for energy and environmental associated problems. Conventional sources of electrical energy run by traditional fuels (like coal, oil etc.) are immensely polluting. Fuel cell technology offers promising and sustainable options for the future generation energy scenario. The recent commercialization of fuel cell has been given importance due to its higher efficiency and reduced environmental hazards. Though the concept of fuel cells is not new, its background is very old. This article covers the following points: concept of fuel cell, history of fuel cells, fuel cell components, comparison with batteries, classification of fuel cells, current progress of fuel cell components, and its present applications status.

Background: The theoretical foundations of modeling and simulation of the industrial processes are presented. The thermodynamic, hydrodynamic and molecular levels of the process modeling are presented. Method: The hydrodynamic approximations are presented in the cases of the elementary processes modeling. The industrial process modeling is presented in different steps. The first step is the formulation of the physical mechanism of the industrial process and the construction of a mathematical structure, containing the mathematical operators that quantitatively describe the individual physical effects in this mechanism. The introduction of generalized (dimensionless) variables through characteristic scales permits to be made a quality analysis of the industrial processes. Obtaining experimental data and using it to calculate the model parameters by solving an inverse identification problem leads to the final form of the mathematical model. The statistical analysis of the model adequacy leads to the practical applicability of the mathematical model. Conclusion: On this basis, a new approach is presented for the modeling of the mass transfer processes in the column apparatuses.

Background: Urban and industrial wastes can play an important role in heat and power generation, substituting a large part of conventional fuels. However, combustion of these materials may create operational and environmental problems related to their inorganic constituents. Methods: In this work, the slagging/fouling propensities of ashes from municipal and animal wastes were determined through the use of a combination of techniques, such as X-ray diffractometry, ultraviolet and visible spectroscopy, atomic absorption spectroscopy, inductive coupled plasma-mass spectroscopy and fusibility analysis. Control methodologies for mitigating deposition tendency in boilers were applied, i.e. leaching of raw fuels with water and blending them with higher quality woody residues. Results: The results showed that urban and industrial waste ashes were enriched in Ca, P, Si and Mg minerals and micronutrients Cu and Zn. Their alkali-induced slagging/ fouling potential was high. For systems operating below 1000oC, no deposition problems were anticipated. Mixing these waste materials with an agricultural residue led to the production of ashes with melting behaviour and deposition tendency between those of the individual samples. Conclusion: Leaching of raw materials with water resulted in a significant decrease of problematic elements K, Na, P, S, and Cl in ashes and consequently in a great reduction of their slagging/fouling propensity.