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Abstract: Ti modified Pt/ZrO2 catalysts were prepared to improve the catalytic activity of Pt/ZrO2 catalyst for a single-stage WGS reaction and the Ti addition effect on ZrO2 was discussed based on its characterization and WGS reaction test. Ti impregnation into ZrO2 increased the surface area of the support and the Pt dispersion. The reducibility of the catalyst was enhanced in the controlled Ti impregnation (∼20 wt.%) over Pt/ZrO2 by the Pt-catalysed reduction of supports, particularly, at the interface between ZrO2 and TiO2. The significant CO2 gas band in the DRIFTS results of Pt/Ti[20]/ZrO2 indicated that the Ti addition made the formate decomposition rate faster than the Pt/ZrO2 catalyst, linked with the enhanced Pt dispersion and reducibility of the catalyst. Consequently, Ti impregnation over the ZrO2 support led to a remarkably enhanced CO conversion and the reaction rate of Pt/Ti[20]/ZrO2 increased by a factor of about 3 from the bare Pt/ZrO2 catalyst. [Copyright &y& Elsevier]

Abstract: Si-modified Pt/CeO2 catalysts were prepared for a water-gas shift (WGS) reaction and the effects of this silica addition on the textural and structural characteristics, reducibility and WGS reaction performance of Pt/CeO2 were investigated. The surface areas of the prepared catalysts increased and both interplanar spacing and average crystalline size of ceria gradually decreased with Si content, resulting in less crystalline and smaller particles. Si addition up to 20 wt. % facilitated the bulk reduction of ceria by inducing significant hydrogen consumption. The oxygen defects in the support, associated with lower valence state cerium, increased with the Si addition. These modifications offer a promising potential to increase the density of hydroxyl groups on the surface of the ceria and consequently increase the concentration of surface intermediate species. The addition of Si to ceria improved the catalytic performance for the WGS reaction, in spite of its irreducible nature. Pt catalysts supported on Si-modified ceria, with a Si content of 5–10 wt.%, exhibited a 2.5-fold increase in reaction rate and turnover frequency (TOF) compared to that of Pt/CeO2. [Copyright &y& Elsevier]

Abstract: This study investigates the module configuration for upscaling CO2 capture capacity to a bench-scale in hydrogen selective Pd-based composite membranes. In order to confirm effective upscaling, four plate-type membranes of two inch diameter were stacked in a newly designed plate-and-frame type module, reaching a total membrane surface area of 6.64 × 10−3 m2 (66.4 cm2). A pure gas test carried out using H2 and He confirmed that there were no effects of module configuration in gas permeation behavior, indicating that the upscale of the separation capacity by numbering-up of membranes using our module design was successful. The CO2 enrichment test was conducted using a 40%CO2 + 60%H2 mixture (i.e. a similar composition for the coal gasifier after both the shift reaction and H2O removal), under high feed pressure and flow rate, i.e. 600–2100 kPa and 0.48–0.72 N m3 h−1. The mixture gas test confirmed that the bench-scale membrane module could enrich 40% of the CO2 at a feed flow rate of 0.48 N m3 h−1 up to 93% with a hydrogen recovery ratio of >90% at 673 K and a total feed pressure of 2100 kPa, i.e. ∼4 times CO2 enrichment capacity of one membrane. [Copyright &y& Elsevier]

Abstract: In this study, the effect of module configuration on the performance of Pd-based membrane devices was examined using a Pd-Au composite membrane deposited on a porous nickel support. Hydrogen permeation flux, recovery, and CO2 enrichment were experimentally examined using two different modules. The module configuration that had a narrower space between the surface of the membrane and cover plate provided a large linear flow velocity of the gas mixture, which allowed for a reduction in the concentration polarization. The CO2 enrichment capacity of the membrane module with a space distance of 0.4 mm was 4 times higher than the module with a space distance of 2.5 mm. In regards to the process design, the membrane with an effective area of 16.6 cm2 could enrich 40% of the CO2 at a flow rate of 2000 ml min−1 up to 87% with a hydrogen recovery ratio of >90% at 673 K and a total feed pressure of 1600 kPa. [Copyright &y& Elsevier]

Abstract: In this study, we investigate the configuration of a Pd–Au composite membrane on a porous nickel support and membrane modules for withstanding the capture of CO2 from a coal gasifier for a long time. The hydrogen permeation flux, recovery and CO2 capture were experimentally evaluated using two different modules and two conditions. As in our study, the CO2 capturing and durability tests were performed with a 40% CO2/60% H2 feed gas mixture in stainless steel (SS) 316L and 310S membrane modules. As a result, it is achieved the durability tests for more than 1150, 1100 (SS 316L module) and 3150 h (SS 310S module) with pressure cycles from 100 to 2000 kPa at 673 K. The durability of the membranes and membrane modules was demonstrated under pressure cycles from 100 to 2000 kPa at 673 K and the SS 310S module was very stable after 3150 h. The durability test for more than 3000 h demonstrated that there was no significant intermetallic diffusion between the PNS and Pd–Au layer. The CO2 capturing test performed using a 40% CO2/60% H2 mixture confirmed that the CO2 capturing capacity of the membrane and membrane module was 2.0 L/min for a CO2 concentration in the retentate stream of 92.3% and that the hydrogen recovery ratio increased with increasing pressure and reached 93.4%. Furthermore, we suggest that the SS 310S module configuration, CO2 capturing test using Pd–Au/ZrO2/PNS membrane and membrane module is very suitable for application as an Integrated Gasification Combined Cycle (IGCC) system due to very simple numbering-up stackable module design was successful. [Copyright &y& Elsevier]