Adsorption for efficient low carbon hydrogen production: part 1—adsorption equilibrium and breakthrough studies for H2/CO2/CH4 on zeolite 13X

Abstract Reforming of fossil fuels coupled with carbon capture and storage has the potential to produce low-carbon H 2 at large scale and low cost. Adsorption is a potentially promising technology for two key separation tasks in this process: H 2 purification and CO 2 capture. In this work, we present equilibrium adsorption data of H 2 and CH 4 on zeolite 13X, in addition to the already established CO 2 isotherms. Further, we carry out binary (CO 2 –CH 4 ) and ternary (H 2 –CO 2 –CH 4 ) breakthrough experiments at various pressures and temperatures to estimate transport parameters, assess the predictive capacity of our 1D column model, and compare different multi-component adsorption models. CO 2 adsorbs strongly on zeolite 13X, CH 4 adsorbs less, and H 2 adsorbs very little. Thus, H 2 breaks through first, CH 4 second (first in the binary breakthrough experiments) and CO 2 last. Linear driving force (LDF) mass transfer coefficients are estimated based on a single breakthrough experiment and mass transfer is found to be fast for H 2 , slower for CH 4 , and slowest for CO 2 . The LDF parameters can be used in a predictive manner for breakthrough experiments at varying pressures, temperatures, flows, and, though with lower accuracy, even compositions. Heat transfer inside the column is described well with a literature correlation, thus yielding an excellent agreement between simulated and measured column temperatures. Ideal and real adsorbed solution theories (IAST and RAST, respectively) both model the observed breakthrough composition profiles well, whereas extended isotherms are inferior for predicting the competitive behavior between CH 4 and CO 2 adsorption. This study provides the groundwork necessary for full cyclic experiments and their simulation.