Production of Hydrogen from Dimethyl Ether over Supported Rhodium Catalysts

Abstract

Infrared (IR) spectroscopy revealed that dimethyl ether (DME) undergoes partial dissociation on pure and rhodium‐containing CeO2 at 300 K to yield methoxy and methyl species. This process is promoted by the presence of rhodium. By means of thermal desorption measurements (TPD), the adsorption of DME on Rh/CeO2 at 300 K and subsequent decomposition of DME (Tp≈370 K), releasing H2, CO, CO2, and CH4, with Tp between 420 and 673 K, were ascertained. Rh/CeO2 is an effective catalyst for the decomposition of DME to give H2 (29–35 %), CO (27–30 %) and CH4 (32–38 %) as major products with complete conversion at 673–723 K. Adding water to DME changed the product distribution and increased the selectivity of H2 formation from 30–35 % to 58 % at 723 K. In situ IR spectroscopy showed absorption bands of CO at 2034 and 1893 cm−1 during the reaction at 673–773 K. Deactivation of the catalyst did not occur at 773 K during the time measured (approximately 10 h). Rh deposited on carbon Norit also exhibited a high activity towards the decomposition of DME, but the selectivity towards hydrogen was lower.

Infrared spectroscopic study of dimethyl ether carbonylation catalysed by TiO2-supported rhodium carbonyls

“…These results indicate the formation of hydrogen bonds between DME molecules and the initially present isolated hydroxyl groups, as others have also proposed for the molecular adsorption of DME on CeO 2 , Al 2 O 3 and zeolites. 22,23,41 This conclusion is confirmed by the appearance of IR bands at 2979, 2891, 1170 and 1093 cm −1 in the spectra of the sample in flowing DME (Fig. 3a).…”

“…18 IR spectra of the functioning catalyst allowed identification of surface reaction intermediates, showing that the catalyst was bifunctional, with CO being activated on Rh + sites and methanol on neighbouring Ti 4+ sites of the support in the form of linear methoxy species. Because there are some reports [21][22][23] suggesting that DME can be adsorbed dissociatively on metal oxides in the form of methoxy species, we decided to extend our investigation of TiO 2 -supported Rh catalysts to the DME carbonylation to give methyl acetate and explore the participation of methoxy species derived from DME as possible reaction intermediates.…”

Production of hydrogen from dimethyl ether on supported Au catalysts

“…As it is non-toxic, thus more preferable compared to methanol to use it as a hydrogen carrier for fuel cells. The decomposition and reforming of DME to hydrogen were also investigated on various catalysts [8][9][10][11][12][13][14][15][16][17][18]. The more effective ones are the Pt metals, which are able to rupture the C-C bond.…”

Rh‐Based Nanocatalysts for Heterogeneous Reactions

“…Unlike other PGMs, the use of Rh has been mainly limited to catalysis. Rh‐based nanocatalysts have been used for a wide range of industrial processes, such as petroleum refining and fine chemical production . This section will focus on the Rh‐based heterogeneous nanocatalysts mediated catalysis of methane conversion, hydrogen generation, and hydroformylation of olefins.…”