Different Feed Mixtures for the Sorption-Enhanced Methanation (SEM) Process on a Lab-Scale TRL-3 Fixed-Bed Reactor
Laura Gómez, Isabel Martínez, Gemma Grasa, Ramón Murillo
Abstract
This work presents an exhaustive analysis of different variables that affect the sorption-enhanced methanation (SEM) process for synthetic natural gas (SNG) production. The effect of temperature and inlet gas composition including the presence of other compounds (CH 4, C 2 H 4, and higher hydrocarbons) was carefully investigated for a feed gas based on H 2 /CO 2 or H 2 /CO 2 /CO mixtures. All of these variables were experimentally evaluated using two commercial materials in the bed, namely, a Ni-based catalyst and a zeolite 4A, in a lab-scale TRL-3 fixed-bed reactor. The reactor operated at 10 bar, temperatures ranging between 200 and 230 °C, and gas space velocities ranging from 0.8 to 1.4 kg C /kg cat ·h. These experiments demonstrated that pure CH 4 production was exclusively achieved when using H 2 /CO 2 /CO mixtures as feed gas. When the reactor was fed with synthetic syngas, H 2 contents above the stoichiometric value were necessary for converting all of the hydrocarbons present in the mixture. Pure CH 4 streams were obtained for approximately 16 min under operating conditions more realistic (200 °C, 10 bar, and 1.4 kg C /kg cat ·h) in the SEM stage with synthetic syngas. By comprehending and optimizing the effect of these variables, it is possible to enhance the efficiency and reproducibility of large-scale SNG production, thus facilitating its implementation in various technological applications.