(462a) A General Adsorption/Reaction Framework for Modular and Multi-Functional Process Design

Modular chemical processes are easily deployable for small scale operations in remote locations to produce value-added chemicals from unconventional resources and distributed feedstocks such as stranded natural gas, CO₂ from flue gas and associated shale gas. The advantages of modular processes include compactness, prevention of inefficiencies of on-site equipment manufacturing, freedom of constructing high-quality equipment in specialized locations, and faster production time. However, modular processes often fail to achieve economies of scale. One way to address this challenge is to design multifunctional modular processes using existing single-functional materials. To this end, we first propose a multi-material design approach which integrates multiple phenomena within a single unit and thereby leads to multifunctional modular processes using existing materials. We use a systematic framework to select and arrange materials (e.g., adsorbent and catalyst blocks) with unique tasks (e.g., adsorption, reaction, storage) in a sequential block-by-block arrangement inside a packed column, and configure operational cycles for integrated, periodic and multifunctional processes. The task-integrated column operates in a cyclic or periodic manner, where each cycle consists of several steps. We use a single superstructure that embeds different design alternatives using blocks, where each block represents a specific material performing a specific task for a specific time step. The functional block-based superstructure is general such that it contains numerous cyclic process configurations for separation processes including pressure/temperature swing adsorption (PSA/TSA), as well as for integrated separation-conversion processes including sorption-enhanced reaction processes (SERP).

Next, in order to accurately predict the performance of different processes generated via multi-material design, we develop Generalized Reaction-Adsorption Model (GRAM) – a high-fidelity process model for dynamic adsorption-reaction systems. GRAM is a one-dimensional, pseudo-homogeneous, non-isothermal, non-adiabatic, and non-isobaric model that captures the reaction and adsorption dynamics in hybrid adsorption-reaction systems. The model is validated using different experimental data from literature. Specifically, the model predictions show agreement with experimental observations for sorption-enhanced steam-methane reforming (SMR)^[1,3], sorption-enhanced reverse water gas shift (RWGS)^[2], and conventional SMR^[4,5]. Computationally, the model handles multi-feed, multi-functional and multi-product processes well.

The GRAM model is further incorporated within the multi-material design framework to design several novel multifunctional modular processes for cost-effective carbon capture and utilization using unconventional energy sources such as stranded and distributed natural gas, CO₂-contaminated shale gas, biogas, landfill gas, fuel gas and flare gas. The objective is to produce valuable products such as hydrogen and syngas. Computational studies are performed for several configurations of the column containing (i) pure catalyst, (ii) pure adsorbent, (iii) heterogeneously-compartmentalized adsorbent and catalyst, and (iv) homogeneously-distributed uniform mixture of adsorbent and catalyst. These intensified processes use sections of adsorbent and catalyst for simultaneous capture and conversion of reactants.

 

References:

^[1] Carvill, B.T., Hufton, J.R., Anand, M., Sircar, S. Sorption-Enhanced Reaction Process. AIChE Journal. 1996.

^[2] Jang, H.M., Lee, K.B., Caram, H.S., Sircar, S. High-purity hydrogen production through sorption enhanced water gas shift reaction using K₂CO₃-promoted hydrotalcite. Chemical Engineering Science. 2012.

^[3] Hufton, J.R., Mayorga, S., Sircar, S. Sorption-enhanced reaction process for hydrogen production. AIChE Journal. 1999.

^[4] Shu, J., Grandjean, B.P.A., Kaliaguine, S. Methane steam reforming in asymmetric Pd- and Pd-Ag/porous SS membrane reactors. Applied Catalysis. 1994.

^[5] Gallucci, F., Paturzo, L., Basile, A. A simulation study of the steam reforming of methane in a dense tubular membrane reactor. International Journal of Hydrogen Energy. 2004.