Studies on water–gas-shift enhanced by adsorption and membrane permeation

Abstract

A new sorption enhanced membrane reactor (SEMR), consisting of a packed adsorbentcatalyst bed (10% CuO/CeO 2 catalyst and a hydrotalcite-derived Mg-Al mixed oxide) around a tubular Pd/Ag hollow fibre membrane, has been proposed to obtain high purity H 2 and simultaneous capture of CO 2 during the water gas shift reaction. The H 2 yield at 350ºC using the SER was 80%, which is 33% higher than that obtained in the traditional FBR and 18% higher than the corresponding thermodynamic equilibrium.However, due to the high CO/H 2 O ratio (R > 1), undesirable side-reactions such as C deposition become important at temperatures higher than 400ºC. A similar behaviour was observed using the SEMR, however in this case, a high purity CO x free H 2 production was obtained. This preliminary study shows relevant data obtained using a SER and the new SEMR, which allows for the better understanding and design of multifunctional catalytic reactors.

Hydrogen production in a Pore-Plated Pd-membrane reactor: Experimental analysis and model validation for the Water Gas Shift reaction

“…In this manner, H 2 is produced by mature and consolidated technologies from hydrocarbons at the first stages, integrating process intensification technologies and CO 2 sequestration, and it is progressively moved to renewable sources. At this point, the use of membrane technology is attracting the interest of the scientific community due to its potential for controlling CO 2 emissions and increasing energy efficiency [5,6].…”

Enhanced hydrogen production from thermochemical processes

“…Relative to large-scale experimental demonstrations, simulations offer an inexpensive and less physically-intensive route towards the same goal. One example where simulation work could save time is validating a hypothesis mentioned by García-García et al 352 They suggested that uniform distribution of catalyst and sorbent along a fixed-bed reactor will not be the optimal configuration. Most of the gasification/reforming/WGS reactions occurs towards the feedstock inlet of the reactor, so it is more logical to have catalysts positioned near the reactor inlet and sorbents/membranes further down the reactor.…”

“…The large size of the fluidised reactor they used limited the shift effect from membrane permeation owing to a low membrane area-toreactor volume ratio. A compact design by combining catalyst and sorbents inside a membrane reactor which has a higher membrane area-to-reactor volume ratio was designed by García-García et al 352 They deployed a Cu-based catalyst and hydrotalcite sorbent in a palladium membrane reactor to enhance WGS, observing >90% CO conversion for the sorptionenhanced membrane reactor. This was an improvement relative to the 80% conversion obtained in the sorptionenhanced reactor and the 50% conversion for a traditional fixed-bed reactor.…”

“…However, this may not be optimal. García-García et al 352 pointed out that using CO2 sorbent in the first half of the reactor where the CO2 partial pressure is low can be unnecessary. CO2 sorption and H2 permeation are only required when considerable CO2 and H2 have been produced and the initial reaction driving force reduces; however, at the inlet of the reactor, the gases have yet to react/come into contact with the catalyst.…”

Sorption-enhanced reforming of bioethanol in dual fixed bed reactor for continuous hydrogen production

“…CO þ H 2 O % H 2 þ CO 2 D r H 0 298 ¼ À41 kJ/mol (2) its removal by the reaction CaO þ CO 2 % CaCO 3 D r H 0 298 ¼ À178 kJ/mol (3) results both in the higher conversion extent and better hydrogen purity.…”