Juan Carlos Beltrán-Prieto

A Review of Catalytic Systems for Glycerol Oxidation: Alternatives for Waste Valorization

Endeavours leading to the study of glycerol oxidation result from the imperative necessity for wise utilization of surplus glycerine generated as by-product from biodiesel manufacture. The oxidation of glycerol is one of the most promising reactions as it leads to the generation of valuable glycerol derivatives that find broad application in pharmaceutical, polymer, and food industries. This review highlights the processing alternatives for glycerol by means of biocatalyst-mediated, heterogeneous, homogeneous, and electrochemical oxidation. The current state of the art is evaluated and recommendations for further research and future directions are included.

DEVELOPMENT OF AN HPLC METHOD FOR THE DETERMINATION OF GLYCEROL OXIDATION PRODUCTS

An HPLC method for the separation of glycerol oxidation products, namely glyceraldehyde, dihydroxyacetone, mesoxalic, tartronic, and glycolic and glyceric acids on an ion-exchange 8% cross-linked calcium sulfonated divinylbenzene-styrene resin column was developed and validated. The conditions reported include temperature (70°C), flow rate (0.5 mL/min) and concentration of the mobile phase (3 mM H2SO4) using isocratic elution with ultraviolet and refractometric detectors. The effect of the mobile phase flow rate and concentration as well as column temperature on the resolution of peaks is described. Excellent correlation coefficient in the calibration model was observed for all analytes over the concentration range of 0.5 to 10 mg/mL. The method was also validated in terms of intra-day precision, sensitivity, accuracy, and detection and quantification limits. The method conditions were applied to the identification of products derived from the chemical oxidation of glycerol. Supplemental materials are available for this article. Go to the publishers online edition of the Journal of Liquid Chromatography & Related Technologies to view the supplemental file.

Estimation of psychrometric parameters of vapor water mixtures in air

In the present paper, a Visual Basic program was developed by describing the set of equations required to determine the value of seven different psychrometric properties (partial pressure of water vapor, absolute humidity, percentage humidity, relative humidity, dew point temperature, humid heat, humid volume or adiabatic saturation temperature) for mixtures of water vapor in air given the dry bulb temperature, the total atmospheric pressure and one additional parameter. Eight different cases are studied according to the corresponding input parameters.

Mathematical model of the bleaching process with chemical kinetics of first and general order

Mathematical modeling of the bleaching process with a chemical reaction and diffusion of bleaching agent into a thin polymeric matrix film by movement through the micropores is studied in the present paper. The model was developed after considering theoretical methods of chemical engineering, the physical operation mechanism of the bleaching process and the main parameters that influence the diffusion mechanism. The efficiency factor for chemical kinetics of first and nth order processes were described using analytical solutions and perturbation methods. For the solution of the dynamic model, two cases of boundary conditions were explored. The first case describes diffusion in a well-stirred medium and the second case describes the situation when the bulk fluid moves slowly and interfacial resistance is present. In the latter case, the difference finite method was used as numerical tool for solving the problem and finding the concentration profile in the direction of the x-axis. Accordingly, experimental measurements were performed to determine the effective diffusion coefficient of bleaching agent in a polymeric matrix.

Study of parameters affecting the conversion in a plug flow reactor for reactions of the type 2A→B

Modeling of chemical reactors is an important tool to quantify reagent conversion, product yield and selectivity towards a specific compound and to describe the behavior of the system. Proposal of differential equations describing the mass and energy balance are among the most important steps required during the modeling process as they play a special role in the design and operation of the reactor. Parameters governing transfer of heat and mass have a strong relevance in the rate of the reaction. Understanding this information is important for the selection of reactor and operating regime. In this paper we studied the irreversible gas-phase reaction 2A→B. We model the conversion that can be achieved as function of the reactor volume and feeding temperature. Additionally, we discuss the effect of activation energy and the heat of reaction on the conversion achieved in the tubular reactor. Furthermore, we considered that dimerization occurs instantaneously in the catalytic surface to develop equations for the determination of rate of reaction per unit area of three different catalytic surface shapes. This data can be combined with information about the global rate of conversion in the reactor to improve regent conversion and yield of product.Modeling of chemical reactors is an important tool to quantify reagent conversion, product yield and selectivity towards a specific compound and to describe the behavior of the system. Proposal of differential equations describing the mass and energy balance are among the most important steps required during the modeling process as they play a special role in the design and operation of the reactor. Parameters governing transfer of heat and mass have a strong relevance in the rate of the reaction. Understanding this information is important for the selection of reactor and operating regime. In this paper we studied the irreversible gas-phase reaction 2A→B. We model the conversion that can be achieved as function of the reactor volume and feeding temperature. Additionally, we discuss the effect of activation energy and the heat of reaction on the conversion achieved in the tubular reactor. Furthermore, we considered that dimerization occurs instantaneously in the catalytic surface to develop equations for ...

Non-isothermal modeling of glycerol oxidation reaction and estimation of thermodynamic parameters

The paper presents determination of adiabatic temperature rise during the oxidation of glycerol to glyceraldehyde with hydrogen peroxide in order for estimating its potential hazardous behavior. Estimation of enthalpy of the reaction was carried out by using thermodynamic tables and the bond energy method. The Nonisothermal reaction system for glycerol oxidation was described on the basis of a dynamic modeling proposal, considering the energy balance in the reactor to describe the final stage in the process of glycerol oxidation. The objectives of the present study were determination of the physic-mathematical model for glycerol oxidation, performance of the linearization of the proposed model and determination of transfer function for control purposes.

Mathematical Modeling of Heat Loss of a Sphere in Contact with a Well Stirred Fluid

The knowledge of several transport properties is important especially when heat transfer has to be evaluated. However, not always the data such as thermal diffusivity is known or available for specific types of material. In this paper, a study was performed to describe the equations that lead to the calculus of thermal diffusivity, heat transfer and calculus of temperature in function of time of a sphere particle that is immersed in a well stirred fluid. The model obtained was tested by comparing the predicted thermal diffusivity value of an orange and the real value.