The impact of zeolite pore structure on the catalytic behavior of CuZnAl/zeolite hybrid catalysts for the direct DME synthesis

García‐Trenco, Andrés; Valencia, Susana; Martı́nez, Agustı́n

doi:10.1016/j.apcata.2013.08.038

Cited by 59 publications

(50 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…García-Trenco et al reported detrimental interactions between Cu/ZnO/Al 2 O 3 and HZSM-5 in the hybrid catalysts prepared by slurry or grinding methods, leading to a dramatic loss of the available Brønsted acid sites through partial exchange of zeolite protons by Cu 2+ and Zn 2+ , and blockage of the zeolite micropores by metallic catalyst particles [8]. The same group also found a correlation between the amount of the extra framework aluminum (EFAL) species on the external surface of the zeolite and the deactivation of the Cu-based methanol synthesis catalyst during the direct DME synthesis over the hybrid catalyst prepared by grinding [9,10]. They hypothesized that EFAL species may migrate onto the Cu-based catalyst through a water assisted surface diffusion mechanism and modify the interaction between ZnO x and Cu, causing progressive deactivation of the active copper sites [9].…”

Section: Ch 3 Oh(g)mentioning

confidence: 70%

“…However, such deactivation was associated with a considerable Fischer-Tropsch activity and paraffin formation, which is not common for typical Cu-based methanol synthesis catalysts. In addition, as mentioned earlier, detrimental interactions between metallic and acid components of the hybrid catalyst [9][10][11][12] as well as methanol dehydration (by)products (water [16] and hydrocarbons [31]) are reported to be influential on methanol synthesis catalyst deactivation during the direct DME synthesis.…”

Section: Catalyst Deactivationmentioning

confidence: 99%

See 1 more Smart Citation

Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

et al. 2016

View full text Add to dashboard Cite

Direct dimethyl ether (DME) synthesis from synthesis gas is studied with regard to potential effects of methanol dehydration on methanol formation and copperbased catalyst performance. For this, the influence of the operating conditions (space velocity, temperature, pressure, time-on-stream and syngas composition) on activity, selectivity and stability of the catalyst was studied and compared for methanol synthesis and direct DME synthesis. The advantage of the direct over the two-step DME synthesis is apparent at conditions where syngas conversion to methanol is thermodynamically limited. However, under the applied operating conditions, results suggest that combining methanol synthesis and dehydration has a negative effect on the methanol formation kinetics. The origin of the observed phenomena is investigated by varying dehydration catalyst and by introducing dehydration products (DME and water) into the methanol synthesis feed. Choice of the solid acid catalyst does not seem to affect methanol formation, and DME is also found to be practically inert over the methanol synthesis catalysts. Water injection, on the other hand, led to a significant decrease in the methanol synthesis rate. Thus, formation of an additional amount of water through methanol dehydration might be an explanation for the lower methanol formation rate in the direct DME synthesis.

show abstract

Section: Ch 3 Oh(g)mentioning

confidence: 70%

Section: Catalyst Deactivationmentioning

confidence: 99%

Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Furthermore, zeolites are more resistant than -Al 2 O 3 towards poisoning of acid sites by the water by-product [4,5,6]. Among the zeolites, the medium pore ZSM-5 (MFI) has been by far the most widely applied as the acid component in bifunctional DME synthesis catalysts [5,7,8,9,10,11], though other zeolites such as ferrierite, MCM-22 and its delaminated counterpart ITQ-2, IM-5, and TNU-9 have also been investigated [12,13].…”

Section: Introductionmentioning

confidence: 99%

The influence of zeolite surface-aluminum species on the deactivation of CuZnAl/zeolite hybrid catalysts for the direct DME synthesis

García‐Trenco

Martı́nez

2014

Catalysis Today

Self Cite

View full text Add to dashboard Cite

ElsevierGarcía Martinez Feliu, A. (2014). The influence of zeolite surface-aluminum species on the deactivationof CuZnAl/zeolite hybrid catalysts for the direct DME synthesis. Catalysis Today. 227:144-153. doi:10.1016Today. 227:144-153. doi:10. /j.cattod.2013 AbstractIn this work, an original approach for preparing Cu-ZnO+H-ZSM-5 (Si/Al=15, denoted as Z5) hybrid catalysts displaying enhanced stability during the direct DME synthesis from syngas is presented. The adopted preparation strategy was based on the effective confinement of the copper catalyst within the pores of an SBA-15 silica carrier (d pore = 7.0 nm) prior to mixing with the acid zeolite. In order to maximize the Cu-ZnO interface area (where active Cu 0 sites are likely located) the walls of the SBA-15 silica were coated with a near-monolayer of ZnO (17 wt% Zn) prior the incorporation of copper (in concentrations of 10, 15, and 20 wt%) by the so-called ammonia-driving deposition-precipitation (ADP) method. Copper nanoparticles sizing 5-6 nm after H 2 -reduction (HRTEM) were effectively confined inside the SBA-15 mesopores (as supported by HAADF-STEM) for Cu loadings of up to 15 wt%. Higher Cu loadings (20 wt%) lead to large, XRD-visible, CuO nanoparticles residing out of the SBA-15 pores. The confined catalyst loaded with 15 wt% Cu (15Cu/Zn@S15) displayed the highest Cu 0 surface area (determined by N 2 O-RFC) and methanol synthesis activity. Then, hybrid catalysts based on this methanol synthesis function (15Cu/Zn@S15+Z5) were prepared in a 15Cu/Zn@S15:Z5 mass ratio of 2:1 by two methods: a) grinding the mixture of powders prior to pelletizing (method G), and b) mixing the pre-pelletized components (method M). Equivalent hybrids comprising a conventional coprecipitated Cu-ZnO-Al 2 O 3 (CZA) catalyst were also prepared for comparative purposes (CZA+Z5). The catalysts were evaluated for direct DME synthesis (533 K, 4.0 MPa) in runs lasting ca. 24 h. It was found that the confined 15Cu/Zn@S15+Z5 hybrids deactivated at a much lower rate than those based on CZA regardless the method of preparation. In turn, while conventional CZA+Z5 catalysts prepared by grinding (G) experienced a higher deactivation than that obtained by mixing (M) due to the contribution of detrimental interactions between the copper and zeolite components in the former, no differences in the deactivation rate were observed for the 15Cu/Zn@S15+Z5 hybrids prepared by grinding and mixing. The improved stability of these hybrid catalysts is accounted for by the inhibition of both detrimental interactions (by avoiding the direct contact of copper active sites and the zeolite surface) and extensive metal sintering (by limiting the extent of Cu 0 crystal growth) induced by the effective confinement of the Cu-based catalyst within the SBA-15 pores.

show abstract

“…Most often, the well-known heterogeneous Cu-ZnO-Al 2 O 3 ternary methanol catalyst is combined with -Al 2 O 3 or zeolites for methanol dehydration. [11][12][13][14][15][16] Typically, the calcined CuO-ZnO-Al 2 O 3 precursor is mixed with the acid catalyst, and the resulting mixture reduced to give the active catalyst, containing metallic Cu. 13,15,17,18 However, such a methodology is not optimized for the two catalytic functions and thus, more targeted strategies have recently been reported.…”

Section: Introductionmentioning

confidence: 99%

“…[11][12][13][14][15][16] Typically, the calcined CuO-ZnO-Al 2 O 3 precursor is mixed with the acid catalyst, and the resulting mixture reduced to give the active catalyst, containing metallic Cu. 13,15,17,18 However, such a methodology is not optimized for the two catalytic functions and thus, more targeted strategies have recently been reported. [19][20][21][22][23] Tsubaki et al prepared core-shell hybrid catalysts, where the methanol synthesis is catalysed by a CuZnO-Al 2 O 3 core and it is dehydrated to DME by a zeolite shell.…”

Section: Introductionmentioning

confidence: 99%

A one-step Cu/ZnO quasi-homogeneous catalyst for DME production from syn-gas

García‐Trenco

White

Shaffer

et al. 2016

Catal. Sci. Technol.

View full text Add to dashboard Cite

ARTICLEThis journal is © The Royal Society of Chemistry 20xxJ. Name., 2013, 00, 1-3 | 1 Please do not adjust marginsPlease do not adjust margins a. Department of Chemistry, Imperial College London, South Kensington, London, UK, SW7 2AZ; c.k.williams@imperial.ac A simple one-pot synthetic method allows the preparation of hybrid catalysts, based on colloidal Cu/ZnO nanoparticles (NPs), used for the liquid phase synthesis of DME from syngas. The method obviates the high temperature calcinations and pre-reduction treatments typically associated with such catalysts. The hybrid catalysts are applied under typical industrially relevant conditions. The nature of the hybrid catalysts, the influence of the acid component, mass ratio between components, and Cu/Zn composition are assessed. The best catalysts comprise a colloidal mixture of Cu/ZnO NPs, as the methanol synthesis component, and -Al2O3, as the methanol dehydration component. These catalysts show high DME selectivity (65-70 %C). Interestingly, the activity (relative to Cu content) is up to three times higher than that for the reference hybrid catalyst based on the commercial Cu/ZnO/Al2O3 methanol synthesis catalyst. The hybrid catalysts are stable for at least 20 h time-on-stream, not showing any significant sintering of the Cu 0 phase. Post-catalysis,TEM/EDX shows that the hybrid catalysts consist of Cu 0 and ZnO NPs with an average size of 5-7 nm with -Al2O3 particles in close proximity.

show abstract

The impact of zeolite pore structure on the catalytic behavior of CuZnAl/zeolite hybrid catalysts for the direct DME synthesis

Cited by 59 publications

References 74 publications

Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

The influence of zeolite surface-aluminum species on the deactivation of CuZnAl/zeolite hybrid catalysts for the direct DME synthesis

A one-step Cu/ZnO quasi-homogeneous catalyst for DME production from syn-gas

Contact Info

Product

Resources

About