Novel Thermal-Swing Sorption-Enhanced Reaction Process Concept for Hydrogen Production by Low-Temperature Steam−Methane Reforming

Abstract

Hydrogen production by steam reforming of natural gas is a well-established technology. The possibility of using hydrogen, a nonpolluting fuel, in fuel cells has brought new interest in developing small, efficient, fuel-cell grade hydrogen production units for residential or industrial use. A novel, step-out, low-temperature, steam−methane reforming (SMR) process concept called “thermal-swing sorption-enhanced reaction” (TSSER) is described. The concept simultaneously carries out the SMR reactions at 490−590 °C and removes the byproduct CO2 from the reaction zone in a single unit operation, thereby (a) circumventing the thermodynamic limitations of the SMR reactions and (b) directly producing a fuel-cell grade H2 product with very high CH4-to-H2 conversion. A K2CO3 promoted hydrotalcite is used as the CO2 selective chemisorbent in the reactor, which is periodically regenerated by steam purge at 590 °C. Model simulations of the TSSER process using recently measured CO2 chemisorption characteristics of the promoted hydrotalcite indicate that a very compact H2 generation unit can be designed that requires relatively low amounts of steam for regeneration. New CO2 desorption data from the chemisorbent and its thermal stability are reported.

Hydrogen production by sorption-enhanced steam reforming of glycerol

“…Generally, an integral fixed-bed reactor with a mixture of the steam reforming catalyst and solid sorbent to selectively remove CO 2 is used. This process is well known as the sorption-enhanced reaction process and has been widely studied by steam methane reforming (Mayorga, et al, 1999;Ding, et al, 2000;Balasubramanian, et al, 1999;Kinoshita, et al, 2003;Yi, et al, 2005;Lee, et al, 2007;Li, et al, 2007;Essaki, et al, 2008;Harrison, 2008). For example, Balasubramanian et al (1999) reported on H 2 production through sorptionenhanced reaction process using a laboratory-scale fixed bed reactor containing a reforming catalyst and CaO formed by calcination of high-purity CaCO 3 , the results of which showed that a gas with a hydrogen content up to 95 % (dry basis) could be produced.…”

“…Some studies also showed that CO 2 sorption enhancement enables the use of a lower reaction temperature, which may reduce energy usage and catalyst sintering. At the same time, it is possible for the steam reforming process to 5 use less expensive reactor materials (Ding, et al, 2000;Lee, et al, 2007;Essaki, et al, 2008;Harrison, 2008).…”

High CO2 Storage Capacity in Alkali‐Promoted Hydrotalcite‐Based Material: In Situ Detection of Reversible Formation of Magnesium Carbonate

“…[4][5][6] These materials are currently being studied for CO 2 capture at the intermediate temperatures (300-500 8C) and relatively high pressures (> 25 bar) that are used in the process of hydrogen production. [7][8][9][10][11] In particular, sorptionenhanced water-gas shift (SEWGS) is a technology that is currently at the development stage that can be advantageously used in pre-combustion decarbonisation for CO 2 free electricity production. [12] It combines a high-temperature CO 2 sorbent and a high-temperature water-gas shift catalyst to produce two hot and separate H 2 and CO 2 product streams from syngas.…”

Process intensification aspects for steam methane reforming: An overview

“…These results show the potential of hightemperature PSA cycle for carbon capture. As far as TSA is concerned, recently, Lee et al 80 proposed a strategy that combines SMR with TSA directly producing fuel cell grade hydrogen. A K 2 CO 3 promoted hydrotalcite was used as CO 2 chemisorbent.…”