Reactor sorption-enhanced

Harrison, D.P. and Z. Peng, Low-carbon monoxide hydrogen by sorption-enhanced reaction, Int.. Chem. Reactor Eng., 1, 1-9, 2003. 

Below, we first briefly describe conventional hydrogen production. Then the combination of hydrogen production and CCS is described. Finally, we elaborate on two of the technologies for more efficient hydrogen production with C02 capture that are currently in the R D phase hydrogen membrane reactors and C02 sorption enhanced reactors. 

For combined hydrogen production and C02 capture several novel technologies are in development, most of them for the application in a pre-combustion C02 capture combined cycle. The main focus is to reduce the efficiency penalties and other associated costs of CO2 capture. The most important technologies in the R D phase, membrane reactors and sorption-enhanced reactors, are described below, with special attention paid to the catalytic aspects. 

Fig. 14.8 Schematic representation of sorption-enhanced reforming. The topmost reactor is in reforming mode, the bottom one is being regenerated using steam.

There is a need for low-cost methane steam reforming catalysts that are active at low temperature and resistant to coke formation under membrane reactor conditions. Low-cost (Ni-based) catalysts are also needed that can withstand regeneration conditions in a sorption-enhanced reformer. 

In this section the methods developed in the previous section will be applied to analyze the dynamic behavior of integrated reaction separation processes. Emphasis is placed on reactive distillation and reactive chromatography. Finally, possible applications to other integrated reaction separation processes including membrane reactors and sorption-enhanced reaction processes will be briefly discussed. More details about reactive distillation processes were provided in Ref. [39]. For chromatographic reactors the reader should refer to Chapter 6 of this book, for sorption-enhanced reaction processes to Chapter 7, and for membrane reactors to Chapter 12. 

The theory presented above also applies to other integrated reaction separation processes which fall into the class of systems illustrated in Fig. 5.1. Typical examples are sorption-enhanced gas phase reactions (as described in Chapter 7) or membrane reactors (as described in Chapter 12). 

As in reactive distillation and reactive chromatography, many sorption-enhanced reaction processes are controlled by phase equilibrium in addition to reaction equilibrium. The situation is different for membrane reactors, where phase equilibrium between the phases adjacent to the membrane is often trivial and the process is... 

Ochoa-Fernandez, E., Rusten, H.K., Jakobsen, H.A., R0nning, M., Holmen, A., and Chen, D. Sorption enhanced hydrogen production by steam methane reforming using Ii2Zr03 as sorbent Sorption kinetics and reactor simulation. Catalysis Today, 2005, 106 (1—4), 41. 

Johnsen, K., Ryu, H.J., Grace, J.R., and Lim, C.J. Sorption-enhanced steam reforming of methane in a fluidized bed reactor with dolomite as C02-acceptor. Chemical Engineering Science, 2006, 61 (4), 1195. 

Pressure swing reactors (PSR) or sorption enhanced reaction process (SERP)... 

Tokyo Tech also conducted a conceptual design study on a long-life multipurpose small-size fast reactor with a medium-temperature hydrogen production system using the sorption-enhanced steam-methane reforming reaction [9],... 

Jprgensen [71] simulated a sorption enhanced steam reforming process em-plo3dng an extended PGT model derived by Lindborg [91] and Lindborg et al [92]. The reactor configuration used operating the novel chemical process is defined in table 10.6. 

A fixed bed reactor for production of hydrogen by sorption enhanced steam methane reforming (SE-SMR) using Li2Zr03 as C02-acceptor was investigated by Rusten et al [11] ... 

Chapter 10 contains a literature survey of the basic fluidized bed reactor designs, principles of operation and modeling. The classical two- and three phase fluidized bed models for bubbling beds are defined based on heat and species mass balances. The fluid dynamic models are based on kinetic theory of granular flow. A reactive flow simulation of a particular sorption enhanced steam reforming process is assessed. 

In chap 11 an overview of the basic designs, principles of operation, and modeling of fixed packed bed reactors is presented. The basic theory is applied to describe the performance of particular chemical processes operated in fixed packed bed reactors. That is, porous media reactive flow model simulations of particular packed bed sorption enhanced steam reforming processes are assessed. 

In recent years, new concepts to produce hydrogen by methane SR have been proposed to improve the performance in terms of capital costs reducing with respect to the conventional process. In particular, different forms of in situ hydrogen separation, coupled to reaction system, have been studied to improve reactant conversion and/or product selectivity by shifting of thermodynamic positions of reversible reactions towards a more favourable equilibrium of the overall reaction under conventional conditions, even at lower temperatures. Several membrane reactors have been investigated for methane SR in particular based on thin palladium membranes [14]. More recently, the sorption-enhanced steam methane reforming (Se-SMR) has been proposed as innovative method able to separate CO2 in situ by addition of selective sorbents and simultaneously enhance the reforming reaction [15]. 

The sorbent can also be used in a chemical reaction, with the adsorbed molecule as one of the reaction products. In sorption-enhanced reaction processes, equilibrium-constrained reactions are driven to the product side, that is, to completion by removing one of the products by using a solid sorbent. The advantage of sorption-enhanced reaction is that the conversion and the separation are combined in just one reactor. Apart from potential equipment savings, reduced energy use for the purification of the main product is the driving... 

This chapter is organised as follows firstly, enhanced processes concepts are presented (Section 6.2), then the sorbent properties and performances (Section 6.3), thirdly enhanced reactor configurations (Section 6.4) are discussed and finally, examples of performances and economic benefits of sorption-enhanced processes for CO2 capture are shown (Section 6.5). 

For the last 10-12 years, the development of sorption-enhanced fuel conversion has mainly focused on the further improvement of sorption-enhanced water-gas shift using hydrotalcite-based sorbents. Starting with the sorption-enhanced steam reforming work of Air Products, hydrotalcite-based materials were identified as potentially attractive sorbents for a pressure swing-based sorption-enhanced water-gas shift reactor system. 

Hufton, J.R., Allam, R.J., Chiang, R Middleton, R, Weist, E.L. and White, V. (2004) Development of a Process for CO2 Capture from Gas Turbines Using a Sorption Enhanced Water Gas Shift Reactor System. Proc. 7th Int. Conf. Greenhouse Gas Technologies. Vancouver (Canada). 

Liu, Y.,Li, Z., Xu, L. and Cai, N. (2012) Effect of sorbent type on the sorption enhanced water gas shift process in a fluidized bed reactor. Industrial Engineering Chemistry Research, 51, 11989-11997. 

Iliuta, I., Diuta, M. C., Larachi, F. (2011). Sorption-enhanced dimethyl ether synthesis— multiscale reactor modeling. Chemical Engineering Science, 66, 2241—2251. 

In sorption-enhanced reforming (SER) reactors, one of the products is extracted from the reaction zone, thus shifting the reaction equilibrium to the product side. In SER, the methane steam-reforming catalyst is mixed with a CO2 sorbent ( acceptor ). The CO2 produced during the reaction is adsorbed and the reverse... 

More recently, Solsvik and Jakobsen [140] performed a numerical study comparing several closures for mass diffusion fluxes of multicomponent gas mixtures the Wilke, Maxwell-Stefan, dusty gas, and Wilke-Bosanquet models, on the level of the single catalyst pellet and the impacts of the mass diffusion flux closures employed for the pellet, on the reactor performance. For this investigation, the methanol synthesis operated in a fixed packed bed reactor was the chemical process adopted. In the mathematical modeling study of a novel combined catalyst/sorbent pellet. Rout et al. [121] investigated the performance of the sorption-enhanced steam methane reforming (SE-SMR) process at the level of a single pellet. Different closures... 

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