Modelling and simulation of biodiesel production processes

• Main Author: Novais, Marisa
• Publication Date: 2013
• Other Authors: Tristão, Paulo, Gomes, Helder, Brito, Paulo
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10198/8299

The reduction of CO2 and CH4 emissions to atmosphere is a matter of great concern nowadays since both gases can contribute signi cantly to the so-called greenhouse e ect that describes the trapping of heat near earth s surface by gases in the atmosphere. At the same time CO2=CH4 separations are of interest in treating gas streams like land ll gas, biogas and coal-bed methane. Accordingly, there is a need to investigate on this topic and that can be done with improved e cient technologies to separate or remove CO2 and CH4 from exhaust gases. Two recent reviews discuss this matter with great detail concerning the use of adsorbents (porous solids) based technologies to handle CO2 capture and CO2=CH4 separations [1, 2]. Biogas is mainly composed by CH4 (60 to 70%) and CO2 (30 to 40%) and to obtain a high energy content CO2 needs to be separated from CH4. For this purpose a variety of solid physical adsorbents have been considered including molecular sieve zeolites and a new class of adsorbents named Metal-Organic Frameworks (MOFs). The technology for biogas upgrading using adsorbents is called Pressure Swing Adsorption (PSA). With this technique, carbon dioxide is separated from the biogas by adsorption under elevated pressure. The adsorbing material, is regenerated by a sequential decrease in pressure before the column is reloaded again, hence the name of the technique. In this work, we will present sorption equilibrium, kinetic and xed bed data of CO2, CH4 in MOF-508b and zeolite 13X at 303, 323 and 343 K and partial pressures up to 4.5 bar. These data are tted with appropriate isotherm models. At the same time single, binary and ternary breakthrough curves were measured to provide required data to develop and validate a mathematical model based on the LDF approximation for the mass transfer, which could be used in the implementation (simulation) of a cyclic adsorption processes (PSA) for the puri cation of biogas and CO2 sequestration.