(359f) Development of a 3D-Printed Honeycomb Monolith Adsorbent for CO2 Capture with Electric Swing Adsorption Process | AIChE

(359f) Development of a 3D-Printed Honeycomb Monolith Adsorbent for CO2 Capture with Electric Swing Adsorption Process

Authors 

Regufe, M. J. - Presenter, LSRE - Laboratory of Separation and Reaction Engineering - Associate Laboratory LSRE/LCM
Ferreira, A., LSRE - Laboratory of Separation and Reaction Engineering - Associate Laboratory LSRE/LCM
Loureiro, J. M., LSRE - Laboratory of Separation and Reaction Engineering - Associate Laboratory LSRE/LCM
Rodrigues, A. E., LSRE - Laboratory of Separation and Reaction Engineering - Associate Laboratory LSRE/LCM
Ribeiro, A. M., LSRE - Laboratory of Separation and Reaction Engineering - Associate Laboratory LSRE/LCM
Introduction and Objectives

3D printing technology was developed in 1980, but at the beginning of this century, its development increased significantly. Depending on the application and on the raw materials, the objects can be printed by different methods, such as Direct Ink Writing method. This method allows to print structures with solid free-form fabrication from an ink with high viscosity. This printing is done with a pressure delivery of an ink through one or multiple capillaries or syringes. The great flexibility in the raw materials and in the type of structure’s and dimensions are advantages of this method. Recently, additive manufacturing gained worldwide attention in the development of adsorbents for gas separation processes, especially in monolithic shaped adsorbents production. There are only a few studies about the preparation of adsorbent materials by 3D printing processes, in particular, for application in CO2 capture from flue gases by Electrical Swing Adsorption (ESA) process. As a type of Temperature Swing Adsorption process, known since 1970, in the ESA process the adsorbent is regenerated by increasing the temperature, but this heat is generated by applying an electric current directly in the adsorbent, and the temperature increases through the Joule effect. This type of process could presents main advantages, such as, higher efficiency, minimization of the lost heat, smaller systems needed, purge gas flow can be controlled independently of the heating rate, among others.

In this context, the development of a new material, with electrical conductivity and high CO2 adsorption capacity properties, is the aim of this work.

This work reports the development of a honeycomb monolith with 70% of zeolite 13X and 30% of activated carbon with dimensions of 30×30×43 mm by 3D-printing process.

Results and Discussion

A mixture with 21.1 g of 13X zeolite (Chemiewerk, Kostritz), 9.1 g of activated carbon (Maxsorb MCS-30, Kansai Coke and Chemicals Co Ltd) and 1.5 g of CMC (VWR) of dried powders was prepared in a mixing chamber of a Multi Lab Extruder (Caleva Process Solutions Ltd, England). After that, water was added to form a homogeneous wet mixture. The mixture was loaded in a syringe, which was placed in a Discov3ry Extruder module (Structur3D Printing, Canada) to be printed, using the monolith design constructed in SolidWorks 2017® software. The Discov3ry is adjusted in order to be capable of exerting the required pressure to push the ink through the syringe orifice.

Before the 3D printing step, the prepared ink was analysed in terms of its rheological behaviour. Rotational parallel plate and oscillatory measurements were carried out using a rheometer (Anton Paar GmbH MCR 92, Austria). These rheological measurements demonstrated that the ink has a shear-thinning behaviour and high near-zero viscosity (15701 Pa.s), promoting the deposition process in the printing step and the extrusion with pressure, respectively. For a successful printing step, the important parameters defined were layer height (0.6 mm), wall thickness (0.84 mm), infill density (100%) and print speed (1.5 mm/s). In addition, two fans were used to dry the material during the printing step.

Textural characterization of the honeycomb monolith were done by several techniques, such as, N2 adsorption at 77 K, CO2 adsorption at 273 K, mercury porosimetry and SEM/EDS analyses. This characterization allowed the estimation of the surface area of the material (2028 m2/g, with Langmuir method) and the volume of micropores (0.93 cm³STP/g, with Density Functional Theory). CO2 isotherm showed type I behaviour, according to the IUPAC classification, characteristics of microporous material. Considering the weight proportion of zeolite 13X and AC in the 3D-printed material, it was possible to estimate the loss of CO2 adsorption capacity. At 0.15 bar, the expected value for the CO2 adsorption capacity was of 4.13 mol/kg (i.e., adding 66.7% and 28.7% of CO2 adsorption capacity of zeolite 13X and activated carbon powders, respectively, being 4.6% of binder content). The real capacity measured in 3D-printed honeycomb monolith was 3.49 mol/kg, representing only a loss of about 15% (at 0.15 bar).

Adsorption equilibrium data of pure gases, CO2 and N2, at three different temperatures in the pressure range of 0 to 1.5 bar were measured by gravimetric method using a magnetic suspension balance (MSB, Rubotherm®, Bochum, Germany).

The experimental data was fitted considering the multicomponent Dual-Site Langmuir model. The parameters of Dual-Site Langmuir model were obtained for each adsorbate minimizing the sum of squared absolute errors between the calculated and experimental values. A good fit for modelling the carbon dioxide and nitrogen adsorption on honeycomb monolith was obtained, as can be seen from the comparison between isotherm model and experimental data.

Dynamic studies of the 3D-printed monolith were carried out by single (CO2) and binary (CO2/N2) breakthrough experiments at 298 K and 1.3 bar. A mathematical model, including mass, energy and momentum balance was proposed and implemented in gProms software. Simulations results were validated with the experimental breakthrough results.

Acknowledgments: This work was financially supported by: Associate Laboratory LSRE-LCM - UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC) and national funds through FCT (scholarship programme with reference PD/BD/105981/2014).