Multiscale characterization framework for sorption enhanced reaction processes

Abstract

in Wiley InterScience (www.interscience.wiley.com).A multiscale simulation and characterization framework has been developed for sorption enhanced reaction processes with heterogeneous multifunctional catalysts with sorption properties. Particles with in situ catalytic and sorption functionalities have obvious advantages in achieving high-purity and productivity. These processes are strongly limited by diffusion inside particle. In order to tackle this problem a more detailed characterization at particle level is essential, which is the main objective here. A unified framework has been developed that integrates continuum model at bulk scale with the diffusion-reaction-sorption model at particle porous scale in a fixed-bed reactor. At bulk scale the objectives of purity and productivity are sensitive to various design and operating variables, such as wall temperature, bed voidage and feed compositions, etc. Two important particle level characteristics are also identified: distribution of catalyst and sorbent inside particles, and the ratio of pore radius to tortuosity. It has been demonstrated that considering detailed diffusivity model at porous level offers better insights into catalyst design and process intensification. Natural gas reforming reaction with sorption producing pure hydrogen for fuel cell and combustion applications has been used as a case study to establish the effectiveness of the methodology.

High temperature CO2 sorbents and their application for hydrogen production by sorption enhanced steam reforming process

“…Broda et al [194] For large-scale hydrogen production units where mass transfer limitations can significantly affect the process efficiency, the catalyst-sorbent mixing configuration is an important parameter to be considered. Besides a physical admixture of catalyst with sorbent, hybrid catalyst-sorbent patterns which integrate the catalytic reaction and the CO 2 sorption in a single pellet can present some advantages such as the elimination of mass diffusional limitation and the reduction of reactor volume [197,198]. Several studies have been performed on the development of hybrid catalyst-sorbent materials for SESMR process [199][200][201][202][203][204][205].…”

Kinetic and structural requirements for a CO2 adsorbent in sorption enhanced catalytic reforming of methane – Part I: Reaction kinetics and sorbent capacity

“…A conventional Ni-based steam reforming catalyst and hydrotalcite sorbent are used in several modeling studies to theoretically demonstrate the performance of sorption-enhanced steam reforming process [5][6][7][8][9][10][26][27][28]. Xiu et al [6] simulated the process in a five-step, one fixed bed reactor using a multi-component system with overall mass and energy balances, pressure drop, and nonlinear adsorption equilibrium for CO 2 over hydrotalcite.…”

Reactor modeling of sorption-enhanced autothermal reforming of methane. Part I: Performance study of hydrotalcite and lithium zirconate-based processes

“…There are significant attempts made to theoretically understand the process performance [11][12][13][14][15][16][17][18]. Xiu et al [11] developed a mathematical model to describe the sorption-enhanced SR in a fixed bed.…”

“…They obtained a CH 4 conversion of 65% and an average H 2 purity up to 80% with traces of CO and CO 2 . Using more reactor length, Xiu et al [12] reached 88% H 2 purity and less than 30 ppm CO. Kapil et al [16] developed heterogeneous bulk scale and particle scale models. They found that the H 2 purity and productivity at bulk scale are sensitive to wall temperature, bed voidage, and feed composition.…”